Mineral Processing Lab Assignments

Assignments Mineral Processing Laboratory

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USMAN UMAR TABASSUM 2008-MIN-36

LAYOUT OF THE HEAVEY MACHINARY MINERAL PROCESSING LAB

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LAYOUT OF THE HEAVEY MACHINARY MINERAL PROCESSING LAB

NAMES OF HEAVY MACHINES

1. DENVER JAW CRUSHER

2. SECONDARY CRUSHER

3. DISC MILL OR PULVARIZER

4. IMPACT CRUSHER

5. HIGH INTENSITY MAGNETAIC SEPERATOR

6. RO-TAP SIEVE SHAKER

7. LOW INTENSITY MAGNETIC SEPARATOR

8. MINERAL JIG (OLD)

9. CENTRIFUGAL HYDROCLASSIFIER

10. SHAKING TABLE

11. ELECTRICAL MINERAL JIG

12. DYNO CONE MACHINE

13. CENTRIFUGAL HYDRO CLASSIFIER (INDUSTRIAL SCALE)

14. AIR CLASSIFIER

15. BALL MILL

16. DENVER DILLON VIBRATING SCREEN

17. HUMPHERY’S SPIRAL CONCENTRATOR FOR COAL

18. HUMPHERY’S SPIRAL CONCENTRATOR FOR METAL

19. GYRATORY SCREEN SHAKER

20. ELECTROMAGNETIC VIBRATING SCREEN (SINGLE DECK)

21. DAVIES DISC MAGNETIC SEPARATOR

22. DRUM FILTER STATION

23. BOWL TYPE OR RAKE TYPE CLASSIFIER

24. RO-TAP SIEVE SHAKER

DOOR MACHINES

STAIRS

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LAYOUT OF HEAVEY MACHINARY MINERAL PROCESSING LAB

PRIMARY CRUSHERS

Primary crushers reduces the large pieces to a size which can be handled by the downstream

machinery.

JAW CRUSHER

A Jaw Crusher is one of the main types of primary crushers in a

mine or ore processing plant. The size of a jaw crusher is

designated by the rectangular or square opening at the top of the

jaws (feed opening). A Jaw Crusher reduces large size rocks or ore

by placing the rock into compression. A fixed jaw, mounted in a

"V" alignment is the stationary breaking surface, while the

movable jaw exerts force on the rock by forcing it against the

stationary plate. The space at the bottom of the "V" aligned jaw

plates is the crusher product size gap, or the size of the crushed

product from the jaw crusher. The rock remains in the jaws until it is small enough to pass

through the gap at the bottom of the jaws.

There are two basic types of jaw crushers, the overhead eccentric style and the double-toggle

style. Which style will work best for a given operation depends upon several factors.

SECONDARY CRUSHERS

It take primary crushed material then work essentially on finer

material and yield more new surface than would a primary

crusher for an equal reduction ratio.

These are basically of two types

1. Impact crushers

2. Roll crushers

3. Cone crushers

DISC MILL

A disc mill, is a type of crusher that can be used to grind, cut,

shear, shred, fiberize, pulverize, granulate, crack, rub, curl, fluff,

twist, hull, blend, or refine. It works in a similar manner to the

http://en.wikipedia.org/wiki/Crusher


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ancient Buhrstone mill in that the feedstock is fed between opposing discs or plates. The discs

may be grooved, serrated, or spiked.

HAMMER MILL OR IMPACT CRUSHER

Impact crushers are used as primary and secondary crushers, depending on the nature of the material in the application. Impact crushers operate by feeding the material into an inner chamber, where it is beat on by large hammers. The material stays inside the chamber until it's at the proper size to fit through the discharge outlet. It is widely used in cement industry and such material is not allowed to be enter in the crusher which consist of more than 15% silica.

HIGH INTENSITY MAGNETIC SEPARATOR Wet-type permanent magnetic separator mainly consists of such four parts as cylinder, magnetic system, cell and transmission parts.

The magnetic separator is applicable for wet mineral separation of such materials as magnetite, pyrrhotine, roasted ore and ilmenite, etc. and it is also applicable for iron removal working of such materials as coal, nonmetal and building materials, etc

RO-TAP SIEVE SHAKERS

Rotap sieve shakers are used for laboratory testing of particle size and size distribution in samples of solid materials. Used for soils, geological materials, alloys, and a host of other solid sample types that have individual particle sizes of from over 5" down to 20 microns.

LOW INTENSITY MEGNATIC SEPARATOR low intensity magnetic separators for recovery of ferro magnetic ores to produce pre- concentrates or concentrates are available with three different tank designs, (concurrent, counter-current and counter-rotation) using a common magnetic drum assembly. When minerals are placed in a magnetic field, there are three reactions which may occur. First, they are attracted to the magnetic field. Second, they are repulsed by the magnetic field. And third, no noticeable reaction to the magnetic field occurs.

http://en.wikipedia.org/wiki/Grinder_(milling)#Buhrstone_mill


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MINERAL JIG (OLD) A jig is a simple mineral processing device using water and the force of

gravity to separate a raw ore stream by density. In many applications this

permits a low grade ore stream to be upgraded in quality sufficient for

sale: Gangue of different density to the valuable component is rejected

into a waste stream, leaving a higher percentage of the valuable

component in the product stream compared to the feed. The

distinguishing characteristic that separates a jig from other gravity and

water based mineral processing devices is the action of a pulsing water

current on a bed of ore to alternately fluidize and compact the bed,

allowing the denser minerals to settle to the bottom of the bed for subsequent splitting into a

product and reject stream.

CENTRIFUGAL HYDRO CLASSIFIER These classifiers use centrifugal forces, similar to cyclones, to separate particles at cut points between 15 and 100 microns. The feed material is carried into the classifier by the primary inlet flow stream. Internal baffles apply drag forces to the coarse particles while allowing air to pass through them for separation of the fines. The heaviest particles drop to the bottom of the classifier and are discharged through a valve.

SHAKING TABLE

Shaking Table is a kind of mineral processing equipment of fine materials according to weight. It is widely used for distilling tungsten, tin, molybdenum, aluminum, zinc, other rare metal and noble metal ore, and it is also applicable for distilling iron, manganese and coal. The rocking bed has the advantages of high enrichment grade, high separation efficiency, easy operation, convenient adjustment, and it can distill the final concentrate and gangue in one step, etc. Concentrating Tables are designed to wet gravity-based separation of minerals and other granular materials.

ELECTRICAL MINERAL JIG (NEW)

A jig is a simple mineral processing device and the force of gravity to separate a raw ore stream by density. Electro-hydraulically operates proportionally control the opening and closing of a refuse gate of a jig.


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The system provides for immediate adjustment of the specific gravity setting which triggers refuse discharge. This allows complete removal of the built-up refuse yet minimizes inadvertent coal losses with the refuse.

DYNO CONE MACHINE It is used for gravity separation. The heavier settles down while the

lighter floats up.

CENTRIFUGAL HYDRO CLASSIFIER (INDUSTRIAL SCALE) These classifiers use centrifugal forces, similar to cyclones, to separate particles at cutpoints between 15 and 100 microns. The feed material is carried into the classifier by the primary inlet flow stream. Internal baffles apply drag forces to the coarse particles while allowing air to pass through them for separation of the fines. The heaviest particles drop to the bottom of the classifier and are discharged through a valve. It is used on industrial scale.

AIR CLASSIFIER Air classification is a process used to separate material according to its

particle equivalent diameter (controlled by its density, volume and

surface characteristics) using a flow of air. It is an approximate sizing

process ordinarily used to separate coarser from finer material; This is

an alternative to screening which is the standard means of sizing

material; however it is inefficient below 250 micron, especially for dry

material. In the mineral industry, it is used for sizing powders with cut

points in the range 5 to 100 micron mineral industry commodities

processed using air classification include calcium carbonate, cement, diatomite, feldspar,

gypsum, kaolin, lime, mica, perlite, phosphates, silica sand and talc.

BALL MILL

A ball mill is a type of grinder used to grind materials into extremely fine

powder for use in mineral dressing processes, paints, pyrotechnics, and

ceramics. Ball mills rotate around a horizontal axis, partially filled with

the material to be ground plus the grinding medium. Different materials

are used as media, including ceramic balls, flint pebbles and stainless

http://goodquarry.com/glossary.aspx?mode=showaz&az_id=19

http://en.wikipedia.org/wiki/Grinder_%28milling%29

http://en.wikipedia.org/wiki/Ceramic

http://en.wikipedia.org/wiki/Flint

http://en.wikipedia.org/wiki/Stainless_steel

http://en.wikipedia.org/wiki/Stainless_steel


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steel balls. . The ball mill is a key piece of equipment for grinding crushed materials, and it is

widely used in production lines for powders such as including cement, silicates, refractory

material, fertilizer, glass ceramics, etc. as well as for ore dressing of both ferrous non-ferrous

metals.

DENVER DILLON VIBRATING SCREEN

Vibrating screen is the major sieving equipment for all kinds of

crushing plants. The vibrating screen is suitable for sieving basalt,

granite, limestone, dolomite, feldspar, iron ore, gold ore, copper,

bauxite and so on. It is widely used for grading and screening materials

in the following fields: minerals, quarry, ,coal dressing, metallurgy,

mine, and so on. They are efficient screening machines for the

classification of bulk material such as coal, minerals.

HUMPHREY’S SPIRAL CONCENTRATOR FOR COAL

Spiral concentrators are a gravity based concentrating device, that separates light density granular and sandy material from heavier density material. In order to have a good separation, there should be a difference in SG's of at least 1.0. Spiral design that allows coal to be re-washed in a second stage Spiral located immediately below the Primary Spiral. Spiral concentrators use differences in density to separate particles simply, efficiently, and cost effectively. Typical capacities for spirals run from 3-5 tons per hour for coal.

HUMPHREY’S SPIRAL CONCENTRATOR FOR METALS Spiral concentrators are a gravity based concentrating device, that separates light density granular and sandy material from heavier density material. Slurry is pumped to the top of the spiral and it enters a feed distributor that evenly distributes the feed to each spiral concentrator. The design and shape of the spiral make it work, when combined with gravitational acceleration. Typical capacities for spirals run from 1-3 tons per hour of feed for minerals.

GYRATORY SCREEN SHAKER This is suitable for heavy materials, powders or granules. It is run by 1/4 HP electric motor through a reduction gear. Gyratory action involves upward and downward movement of the table. Standard gyratory motion produce inclination from the vertical axis and the


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direction of inclination changes continuously in the clockwise direction. The sieve table rotates in 45-degree direction, which makes each square inch of the sieve analysis possible. The whole gear mechanism runs in oil bath made of stainless steel. It is necessary to pour machine oil no. 40 up to level mark.

ELECTROMAGNETIC VIBRATING SCREEN (SINGLE DECK) These are used in grading as well as sieving purposes. These screens are composed of a main frame, electric motor, screen web, eccentric bock, coupler and rubber spring. The different applications of vibrating screens include crushing plant, cement, lime minerals, clay, rubber industries and many more.

DAVIES DISC MAGNETIC SEPARATOR High intensity electromagnetic separator is designed for the continuous removal of ferrous/magnetic particles from liquid based applications. The separator is also capable of separating a high percentage of paramagnetic particles. To clean the separator, contaminates are washed down through the matrix with automatic cycle once the separator is de-energized.

DRUM FILTER STATION

Rotary drum filters offer great flexibility in meeting the needs of producers of many products requiring the separation of liquids from solids. Rotary Drum Vacuum Filter is applied to process and waste slurries for filtering, clarifying, cake washing and extraction, and dewatering. There are many factors affecting the operation of a filtration process. Among these are the need for chemical pretreatment; the need for precoat or filter aid; power, water, air, or other utilities; operator attention; cleaning requirements; and maintenance needs. All of these should be considered when selecting a filter.

BOWL TYPE OR RAKE TYPE CLASSIFIER It is a mechanical classifier utilising rakes. The rakes are actuated by an eccentric motion to dip into the settled material and move it up the incline for a short distance. The rakes are then withdrawn, and return to the starting-point, where the cycle is repeated; the settled material is thus slowly moved up the incline to the discharge. In the duplex type one set of rakes is moving up,while the other set returns.


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LAYOUT OF THE LIGHT MACHINARY MINERAL PROCESSING LAB

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LAYOUT OF THE LIGHT MACHINARY MINERAL PROCESSING LAB

1. INDUCED ROLL MAGNETIC SEPERATOR

2. ISODYNAMIC MAGNETIC SEPERATOR

3. VIBRATORY MILL

4. ULTRA SONIC SIEVE SHAKER

5. SAMPLE DIVIDER

6. SCALE PLATE FORM

7. DIGITAL BALANCE

8. DESICATOR

9. CURICIBLE

10. VOLAND BALANCE

11. HIGH TENSION ELECTRO STATIC SEPERATOR ( SCREEN TYPE)

12. HIGH TENSION ELECTRO STATIC SEPERATOR ( PLATE TYPE)

13. HIGH TENSION ELECTRO STATIC SEPERATOR ( DRUM TYPE)

14. CHEMICAL SHELF

15. DENVER FLOTATION MACHINE (NEW)

16. DENVER FLOTATION MACHINE (OLD)

17. LAB FISHER OVEN

18. LAB FISHER OVEN

19. LAB FISHER OVEN

20. LINDBERG LAB FURNACE

21. AGITATOR OR CONDITIONER

22. REYMOND MILL

23. HARD GROVE GRINDIBILITY TESTING MACHINE

24. RING MILL

25. JAW MILL

26. CYLANDRO CONICAL BALL MILL

27. ROD MILL

28. VIBRO SIEVE SHAKER ( NEW)

29. SAMPLING / SIEVING PLAT FORM


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LAYOUT OF THE LIGHT MACHINERY MINERAL

PROCESSING LAB

INDUCED ROLL MAGNETIC SEPARATOR

Induced roll magnetic separator is basically used for separation

and concentrating of minerals or other materials of low

magnetic susceptibility. Uses for extraction of iron or chromium

bearing minerals from silica sand, the concentration mineral

such as wolframite, the removal of such paramagnetic minerals

such as limonite, siderite etc, from valuable non-magnetic

minerals.

Induced roll magnetic separator is used to extract small magnetic particles from minerals to

produce mineral purification for a wide range of minerals. Material being treated is fed from

the top of the hopper on to a high magnetic roll.

ISODYNAMIC MAGNETIC SEPERATOR

A unique and outstanding research tool for the mineral

investigator. Separates dry granular materials according to their

magnetic susceptibilities. Used at geological and mineralogical

laboratories worldwide, having set the standard for such

separations.

The Isodynamic® Separator consists essentially of an

electromagnet having two long pole pieces shaped to a special contour with a long narrow air

gap between them. Materials to be separated are fed into one end of the magnetic field and

travel through its entire length. The more strongly paramagnetic particles are urged toward the

narrow side of the gap. The grains are intercepted by a dividing edge which directs the two

fractions into separate containers.

The Isodynamic Separator makes sensitive separations of minerals or other grains according to

susceptibility, even of materials not usually thought of as magnetic.

VIBRATORY MILLS

Vibratory mills are for continuous or batch grinding materials to

a very fine end product. Grinding cylinders is placed either

directly above or inclined at 30 degrees to perpendicular. Unique


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vibratory motion, coupled with the use of cylindrical media, allows a dense packing of the

media bed assuring maximum media surface contact and minimum void area when operated

under a low energy condition.

ULTRA SONIC SHIEVE SHAKER

Ultrasonic Sieve Cleaner is specially designed to provide a safe and

effective means for cleaning test sieves. The unit requires little, if

any, maintenance. The cleaner produces ultrasonic vibrations in a

cleaning fluid bath, which cause contaminants to become

dislodged from both the sieve frame and media. Vibrations up to

40,000 per second (40 kHz) are transmitted to the cleaning

solution. Cleaning times range from 5-15 minutes. The unit will clean one 8" (200 mm) diameter

full height test sieve at a time.

SAMPLE DIVIDER

It is used for dividing the sample being used in the lab.

PLATFORM SCALES

Platform scales are specially designed and produced in large

number to meet the requirements of measuring the weight of the

objects. They come in different models, sizes, prices and capacities

to satisfy the requirement. Its capacity is by 100 kg.

ANALYTICAL BALANCE

An analytical balance is used to measure mass to a very high degree of precision and accuracy. The measuring pan(s) of a high precision (0.1 mg or better) analytical balance are inside a transparent enclosure with doors so that dust does not collect and so any air currents in the room do not affect the balance's operation. The use of a vented balance safety enclosure, which has uniquely designed acrylic airfoils, allows a smooth turbulence-free airflow that prevents balance fluctuation and the measure of mass down to 1 μg without fluctuations or loss of product. Also, the sample must be at room temperature to prevent

http://en.wikipedia.org/wiki/Mass

http://en.wikipedia.org/wiki/Milligram

http://en.wikipedia.org/wiki/Dust

http://en.wikipedia.org/wiki/Vented_balance_safety_enclosure

http://en.wikipedia.org/wiki/Room_temperature


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natural convection from forming air currents inside the enclosure, affecting the measure of mass.

DESICCATOR

A desiccators used to refer to a laboratory glassware where things to

be kept inside it are dry and away from the moisture in the air. It is

also known as the dry box due to it keep the thing inside dry, what

makes the thing dry simply the use of a desiccant, an agent to absorb

all moisture in the air of a closure environment.

CRUCIBLE

A crucible is a cup-shaped piece of laboratory equipment used to contain chemical compounds when heated to extremely high temperatures. Crucibles are available in several sizes and typically come with a correspondingly-sized crucible cover (or lid).

Crucible is a refractory container used for metal, glass, and pigment production as well as a number of modern laboratory processes, which can withstand temperatures high enough to melt or otherwise alter its contents

VOLANDBALANCE

The Voland balance is the most fundamental tool in the chemists

arsenal. It is used to determine the masses of, or in other words the

amount of stuff in, objects or samples. Voland Outfit A 004 Assay

Balance Closed | VOLAND & SONS PORTABLE OUTFIT A ASSAY

BALANCE - Voland & Sons Portable Outfit A complete with slant front

assay balance and folding pulp balance and locking French polished

mahogany carrying case 13 in W x 9 1/2 in D x 10 in H; very lightweight construction; equipped

with locking device for beam. It can weigh minimum upto 3 mg.

HIGH TENSION ELECTRO STATIC SEPARATOR (SCREEN TYPE)

http://en.wikipedia.org/wiki/Convection

http://en.wikipedia.org/wiki/Laboratory

http://en.wikipedia.org/wiki/Chemical_compound

http://en.wikipedia.org/wiki/Temperature

http://en.wikipedia.org/wiki/Lid_%28container%29


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HIGH TENSION ELECTRO STATIC SEPARATOR (PLATE TYPE)

Electrostatic plate separators work by passing a stream of particles past a charged anode. The conductors loose electrons to the plate and are pulled away from the other particles due to the induced attraction to the anode. These separators are used for particles between 75 and 250 micron and for efficient separation to occur, the particles need to be dry, have a close size distribution and uniform in shape. Electrostatic plate separators are usually used for streams that have small conductors and coarse non-conductors. The high tension rollers are usually used for streams that have coarse conductors and fine non-conductors.

HIGH TENSION ELECTRO STATIC SEPARATOR (DRUM TYPE)

This high tension electrostatic drum separator is capable of producing

high grade concentrators with fast recovery of valuables owing to three

-step re-cleaning and facility for heating materials. Besides these

feature, it also consumes little electric power and is environment-

friendly. It is uses for Beneficiation of ferrous, non -ferrous and rare

metal ones, Recovery of metals from industrial wastes (electronic or

electrical engineering scrap, cables etc, Recovery of dielectric materials (e. g. plastics) for

recycling, Purification of metal and non -metal powders.

CHEMICAL SHELF

Is used for the storage of the chemicals in the laboratory.

DENVER FLOTAION MACHINE (NEW)

Denver Laboratory Flotation Machine by Metso with suspended type

mechanism, including totally enclosed anti- friction spindle bearing,

stainless tell shaft, stainless steel standpipe with air control valve,

two removable DENVER Urethane diffuser type hoods, and two

removable DENVER Urethane open type impellers of different sizes

or closed type impellor for use in tank. Mechanism is supported on a

spring-balanced movable arm that is raised or lowered on a column

by a hand crank through rack and pinion bearing and can be locked at


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any desired height.

DENVER FLOTAION MACHINE (OLD)

It also has the same description as mention above but this is old.

LAB FISHER OVEN ( SMALL)

A drying oven is a device for applying low heat over a long time to a variety of objects for a variety of purposes. Another use of the drying oven is sterilization and drying for laboratory equipment, such as glassware. A closed chamber for drying an object by heating at relatively low temperatures. This oven is manufactured by FISHER Company and it can use by 220°C.

LAB FISHER OVEN (LARGE)

This oven is also manufactured by FISHER Company and it can use by

250°C.

LINBERG LAB FURNACE

Lindberg furnaces provide fast, efficient, and economical heat-treating. Temperature range to 1400°C. The heat treat furnace system offers a variety of temperature to meet a broad range or process requirements.

AGITATOR

An agitator is a device or mechanism to put something into motion

by shaking or stirring. There are several types of agitators with the

most common are the "straight-vane" and "dual-action." Sonic's

superior performance Typhoon Propeller Mixers and Agitators are

used for mixing and agitating liquids and dissolving and suspending

solids within liquids.

http://en.wikipedia.org/wiki/Device

http://en.wikipedia.org/wiki/Mechanism

http://en.wikipedia.org/wiki/Motion_%28physics%29

http://en.wiktionary.org/wiki/shaking

http://en.wiktionary.org/wiki/stirring


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REYMOND MILL

The Raymond Mill is mainly applied to the powder processing of

mineral products in industries. The Raymond mill can produce

powder from more than 280 kinds of non-flammable and non-

explosive mineral materials with Mohs hardness below 7 and

humidity below 6%. The final size of the Raymond mill is between

613 micron and 440 micron (0.613mm—0.044mm).

HARD GROVE GRINDABILITY TESTING MACHINE

Preiser Scientific’s Grindability Tester is a compact precision built instrument designed specifically for the determination of the relative “hardness” or abrasive potential of coal. Unit is constructed in strict accordance with ASTM Designation D-409 and conforms to procedures proposed by ISO for the determination of the Hardgrove Grindability index of coal and coke.

RING MILL

It is used for pulverising rocks, soil, coal, cement, glass, limestone, bricks, wood, plant material, slags, concrete, etc… for subsequent analysis by instrumental methods or wet chemistry. The noise level is less than 85dB. It provides fast and dust free grinding, homogeneity grinding, very low contamination of samples, easy to clean, low capital cost, long life and maintenance free. Horizontal mills add some additional expense, much of it in using

a vertical output shaft gearbox for the main work roll drive.

JAW MILL ( DODGE TYPE)

A Jaw Crusher is one of the main types of primary crushers in a

mine or ore processing plant. The size of a jaw crusher is designated

by the rectangular or square opening at the top of the jaws (feed

opening). A Jaw Crusher reduces large size rocks or ore by placing

the rock into compression.

CYLINDRO CONICAL BALL MILL

The Conical Mill is most efficient when the maximum feed size is less than 2" and iron contamination is not a factor. A sphere has the greatest volume for a given surface area of any solid. In a typical


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cylindrical mill, it has been proven that most of the work is accomplished in only a portion of the mill cylinder length and the end corners are ineffective.

ROD MILL

These are very similar to ball mills, except they use long rods for

grinding media. The rods grind the ore by tumbling within the mill,

similar to the grinding balls in a ball mill. There are three main types

of rod mill, overflow, end peripheral discharge, and center

peripheral discharge but only the overflow mill is in common

usage. The rod mill performs best when making products having a

top size of 4 mesh to 16 mesh operating in open circuit, or as fine

as 35 mesh operating in closed circuit with a screen or other sizing device.

VIBRO SIEVE SHAKER (NEW)

This is suitable for heavy materials, powders or granules. It is run by

1/4 HP electric motor through a reduction gear. The sieve table

rotates in 45-degree direction, which makes each square inch of the

sieve analysis possible.

SIEVING PLATE FORM/ SAMPLING PLATE FORM

This table is used for preparing the samples which are to be

analyzed.

REFRENCES:

http://www.lindbergmph.com

http://www.outotec.com

http://www.grindermachine.org

http://www.socachim.com

http://www.wkipedia.org http://www.answers.com. http://www.google.com

http://www.lindbergmph.com/

http://www.outotec.com/

http://www.grindermachine.org/

http://www.socachim.com/

http://www.wkipedia.org/

http://www.answers.com/

http://www.google.com/


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INTRODUCTION OF THE JAW CRUSHER

Jaw crusher are primary crushing machines operation almost always dry and are very suitable

for crushing all types of rocks and ores, except where the material is wet and sticky or

malleable. A jaw or toggle crusher consists of a set of vertical jaws, one jaw being fixed and the other

being moved back and forth relative to it by a cam or pitman mechanism.

CLASSIFICATIONS OF JAW CRUSHERS

Jaw crusher are classified by the method of pivoting the swing jaw as describes below:

Blake type

Dodge type

Universal type

BLAKE TYPE JAW CRUSHER

In the Blake type jaw crusher, the jaw is pivoted at the top and thus has the fixed receiving area

and variable discharge opening.

The Blake crusher was patented by W.E. BLAKE in 1858 and variation in detail on basic form are

found in most of the jaw crusher used today.

DODGE TYPE JAW CRUSHER

In the dodge type jaw crusher jaw is pivoted at the bottom, giving it a variable feed area but

fixed delivery area. This is restricted to laboratory use where close sizing is required.

UNIVERSAL TYPE JAW CRUSHER

The universal type jaw crusher is pivoted in an intermediate position and thus have variable

delivery and receiving area.


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But here we concerned with only Blake type jaw crusher because in laboratory we used Blake

type jaw crusher for crushing test of the given sample.

BLAKE TYPE JAW CRUSHER

In the Blake type jaw crusher, the jaw is pivoted at the top and thus has the fixed receiving area

and variable discharge opening.

KINDS OF THE BLAKE TYPE JAW CRUSHER

Basically there are two types of the Blake type jaw crushers:

Double Toggle Jaw Crusher

Single Toggle jaw Crusher

DOUBLE TOGGLE BLAKE TYPE JAW CRUSHER

The oscillation movement is of the swinging jaw is effected by vertical movement of the

pitman. This moves up and down under the influence of the eccentric. The back toggle plate

causes the pitman to move sideways as it pushed upward. The motion is transferred to the

front toggle plate and this in turn cause the swing jaw to close on the fixed jaw. Similarly,

downward movement of the pitman allows the swing jaw to open.

SINGLE TOGGLE BLAKE TYPE JAW CRUSHER

In this type of jaw crusher, the swing jaw is suspended on the eccentric shaft, which allows a

lighter, more compact design than with the double toggle machine. In this machine swing jaw

not only move towards the fixed jaw , under the action of the toggle plate, but it also move

vertically as the eccentric rotates. This elliptical jaw motion assists the in pushing rock through

the crushing chamber. Single toggle machine has double capacity then double toggle of the

same gape.

CONSTRUCTION OF THE SINGLE TOGGLE BLAKE TYPE JAW CRUSHER

Jaw crushers are extremely heavy duty machines and hence must be robustly constructed.

1. MAIN FRAME

The main frame is often made from cast iron or steel, connected

with tie-bolts. It is often made in sections so that it can be

transported underground for installation. Fully stress relieved after

fabrication.


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2. JAWS

The jaws are usually constructed from cast steel and are fitted

with replaceable manganese steel liners, which are bolted in

sections on to the jaws so that they can be removed easily

and reversed periodically to equalize wear. The jaw plate are

smooth themselves, but are often corrugated, being

preferred for hard, abrasive materials.

3. CHEEK PLATES

These are fitted to the sides of the crushing chamber to

protect the side main frame from wear. These are also made

from manganese steel and have the similar life to the jaw

plates.

4. FLY WHEEL

Rotational energy is fed into the jaw crusher eccentric shaft

by means of a sheave pulley which usually has multiple V-

belt grooves. Heavy fly wheel attached to the drive which is

necessary to store energy on the idling half of the stroke and

deliver it on the crushing half.

5. ECCENTRIC SHAFT

Jaw holder is put in motion by the oscillation of an eccentric

lobe on a shaft that goes through the pitman's entire

length. This movement might total only 1 1/2" but produces

substantial force to crush material. This force is also put on

the shaft itself so they are constructed with large dimensions

and of hardened steel.

6. THE TOGGLE PLATE

It serves the purpose of allowing the bottom of the jaw

holder to move up and down with the motion of the

eccentric shaft as well as serve as a safety mechanism for

the entire jaw. It has one small toggle which rest on steel

bearings, at one end of back body of the movable jaw at the

other end on vertically slid able wedge block besides the

main frame.


21


7. JAW-HOLDER & MAIN BEARING HOUSINGS

It Can be removed from the frame as an assembly. The jaw-holder is

a robust box construction with a fully machined face to support the

moving jaw.

BASIC TERMINOLOGIES ABOUT JAW CRUSHER

We are describing some basic terminologies in the below which help us to understand more

about the jaw crushers:

1. GAPE OF THE CRUSHER

The feed opening of the jaw crusher is called Gape. Which is the distance between the

jaws at the feed opening. Which is given as 5” × 6”.

2. SET OF THE CRUSHER

The maximum opening of the jaws at the discharge end is called set. The discharge size

of the material from the crusher is controlled by set. This can be adjusted by using

toggle plates of the required length.

3. THROW OF THE CRUSHER

The jaw is pivoted from above, it moves a minimum distance at the entry point and a

maximum distance at the delivery. This maximum distance is called the throw of the

crusher.

4. NIP ANGLE OF THE CRUSHER

The nip angle describes the angle the stationary jaw plate and the pitman make with each

other. The exact value of this angle isn't quoted or even determinable due to curvature in the

jaws themselves but what is important is how wide vs. narrow it is. Wide nip angles can tend to

expel material as the jaw closes as a large ball might squirt out from under a car tire. If the nip

angle is narrow, not much vertical upward force is generated and more consistent crushing

takes place.

5. FEED MATERIAL

Such a material which is introduced in the crusher for crushing purpose is called the

feed material. It should be 80% to 90% of the gape and it should also be a uniform size.

6. PRODUCT MATERIAL

Such material which is discharge from the set after crushing is called product. The size of

the product can be adjusted by adjusting the size of the set.


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CROSS SECTION OF SINGLE TOGGLE JAW CRUSHER


23


MACHINE STUDY OF LABORTARY JAW CRUSHER AND TO PERFORM A

CRUSHING TEST ON THE GIVEN SAMPLE

APPARATUS/ EQUIPMENT

DENVER LABORTARY JAW CRUSHER

VERNIOR CALIPER

LUMP OF DOLOMITE AS ROCK SAMPLE

PROCEDURE:

1. WE studied the each part of the machine from instructor and draw their rough sketch

and label them.

2. We switched on the machine study the movement of the moving jaw and variation of

the set with motion.

3. We measure the sides of the gape and set.

4. we examine the feed as of dolomite and take the largest lump by taking measurements

with vernier caliper.

5. We introduce the lump in the machine and crushed the enire sample.

6. We examine the product and took the largest lump in the product and record its size.

7. Calculated the reduction-ratio of the machine.

OBSERVATIONS:

NAME DENVER JAW CRUSHER (BLAKE TYPE)

MOTOR HORSE POWER 5 HP

MOTOR R.P.M. 1440

CRUSHER R.P.M. 325-375

MOVABLE JAW DEPTH 14”

FIX JAW DEPTH 12”

WIDTH OF JAW PLATE 6”

CRUSHER CAPACITY 600 Lbs/Hr

FLYWHEEL DIAMETER 18”

FACE OF FLYWHEEL 3 ¼ “


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MAX: FEED SIZE (GAPE) 5”×6”

SIZE OF SET CLOSE ½ “ OPEN 1.25”

FEED DOLOMITE LUMPS

CALCULATIONS:

1. REDUCTION RATIO:

Reduction Ratio =

Reduction Ratio =

Reduction Ratio = 5.002

2. CAPACITY:

Capacity in tons/hour (approx.) from Targets formula =T = 0.6LS

Where,

S = Set I inches

L = Width of Jaw-plate in inches

Capacity = T = 0.6 LS

Capacity = 0.6 * 6 * 1.25

Capacity = 4.5 tons/hour

3. EXPRESS SIZE OF CRUSHER: Size of crusher = Width * Gape

Size of crusher = 5 * 6 inch²

REFRENCES:

MINERAL PROCESSING TECHNOLOGY BY B.A.WILLS

www.flsmidth.com. www.terexjaques.com .

www.westpromachinery.com

http://www.flsmidth.com/

http://www.terexjaques.com/

http://www.westpromachinery.com/


25


INTRODUCTION TO ROLL CRUSHERS

Roll Crushers are compression type crushers, and were once widely used in mining. They have,

within the last 10 or so years, fallen into dis-favor among mining and processing companies but

these are still used in some mills, although they have been replaced in many installations by

cone crushers. They still have a useful application in handling friable, sticky, froze and less

abrasive feeds such as lime stone, coal, chalk, gypsum, phosphate and soft iron ores.

HISTORY OF ROLL CRUSHERS

Rolls were invented more than 100 years ago, recorded of their use in Cornwall going back to

1806. In Early machines, the rolls were mounted on the shafts revolving in open bearings

contained within cast iron side frames. One of the roll was driven positively and the other, or

idler, by friction. To assure rotation of the idler was pressed sideways against the live roll by

heavy weight hung from yoke.

MODERN STANDARD ROLL CRUSHERS

In a standard double roll crusher designs both rolls are positively driven, at much higher speeds,

and breakage is prevented by mounting the bearings of one roll shaft against coil springs while

the other connected to screw mechanism. Spring loading serve as a safety device against un

crushable lumps whereas the screw mechanism provides the set adjustment for different

product sizes.

TYPES OF ROLL CRUSHERS

Roll crushers are also manufactured with only one rotating cylinder while the others are three,

four, or six cylinders. Types of roll crushers are dependent on roll diameters.


26


SINGLE ROLL CRUSHERS

a single roll crusher uses one wheel to grind up mining material, such as coal, salt, ore, chalk and slag. These crushers come with crushing rings, ledges, teeth or shells made of high quality steel. A single roll crusher produces medium particles. The crushing plate has a replaceable comb plate in case of wear and tear.

THREE ROLL CRUSHERS

Three roll crushers perform primary and secondary crushing, reducing material to medium and fine particles. Equipped with three turning wheels, crushing rings or ledges to execute crushing, three roll crushers have equipment that keeps dust from penetrating the machine and interfering with the rollers' performance. The rollers have rotating V-belts that are powered by electrical and gear motors. Three roll crushers accommodate a high capacity and constant flow of material for high volume crushing.

FOUR ROLL CRUSHERS

Four roll crushers grind material into medium particles by the primary crushing process and fine particles by the secondary crushing process. Four roll crushers are mainly used in the fertilizer and chemical industries, and with power plant technology. These crushers have a low dust output, with adjustable roll diameters that control the sizes of particles. Overload protection guards the machine against foreign material destroying the machine.

OPERATION OF THE ROLL CRUSHER

The material is fed at the top through a screen hopper and due to presence of the co-efficient of friction between the rolls surface and ore lumps, a nipping action take place which pulls the lumps downwards. When the lumps passes through the rolls it is crushed to a size equal to or finer than the set. Since the residence time of an ore lump between the rolls is very short, a rolls crusher normally does not produce excessive fines. The machine has been based extensively for preparing feed for gravity separation operations.


27


TYPES OF ROLLS

There are basically three types of rolls are used in roll crushers fir different purposes.

SMOOTH SURFACE ROOLS

These rolls are usually used for fine crushing. Wear on the roll surface is very high, and they often have manganese steel tyre, which can be replaced when worn.

SLUGGER ROLLS

coarse crushing is often performed in rolls having corrugated surfaces, or with stub teeth

arranged to present a chequered surface pattern.

HIGH PRESSUR GRINDING ROLLS

HPGR consists of a pair of counter rotating rolls, one fixed and the other floating. Material is fed between the rolls with the floating roll pressing against the material flow by means of hydraulic pressure in excess of 50 MPa. The resulting force causes the material to compact by interparticle breakage. Pressures and roll speeds are adjusted to obtain optimum grinding conditions. The roll faces are typically studded because of improved wear characteristics.

PRINCIPLE OF THE ROLL CRUSHER

Consider a spherical particle, of radius r, being crushed by a pair of rolls, of radius R, the gap

between the rolls being 2a (fig.). If μ is the coefficient of friction between the rolls and the

particle, Ѳ is the angle formed by the tangent to the roll surfaces at their points of contact with

particle (the angle of nip), and C is the compressive force exerted by the rolls, acting from the

roll centers through particle center, then for particle to be just gripped by the rolls, equating

vertically,


28


C sin Ѳ/2 = μC cos Ѳ/2

μ = tan Ѳ/2

The coefficient of friction between steel and the most ore particles is in the range 0.2-0.3, so that the val , otherwise the particle will slip.

The larger the angle of nip (i.e. the coarser the feed), the slower the peripheral speed needs to

be to allow the particle to be nipped. For smaller angle of nip (finer feed), the roll speed can be

increased, so increasing the capacity. Peripheral speeds vary between about 1 ms-1 for small

rolls, up to about 15 ms-1 for the largest size of 1800 mm diameter upwards.

The value of the coefficient of friction between a particle and moving rolls can be calculated

from the equation

μk = ( ) μ

Where μk is the kinetic coefficient of friction and v is the peripheral velocity of the rolls (ms-1).

MAXIMUM SIZE OF ROCK

Following equation can be used to determine the maximum size of rock gripped in relation to

roll diameter and the reduction ratio (r/a) required. From figer

cos Ѳ/2 =

CAPACITY OF ROLL CRUSHER

The capacity of the rolls can be caldulated in terms of ribbon of material that will pass the space

between the rolls. Thus theoretical capacity is equal to

188.5 N D W sd kg h-1

Where

N is the speed of the rolls (rev min -1)

D is the roll diameter (m) W is the roll width (m) s is the specific gravity of the feed material (kg m-3)


29


d is the distance between the rolls (m) In practice, allowing for voids between the particles, loss of speed in gripping the feed, etc., the

capacity is about 25% of the theoretical.

ADVANTAGES OF ROLL CRUSHERS

They produce very little dust or fines Rolls crushers are effectively used in minerals crushing where the ores are not too

abrasive. Coal plants will use roll crushers, either single roll or double roll, as primary crushers,

reducing the ROM coal.

DISADVANTAGE OF ROLL CRUSHER

The great disadvantage of roll crushers is that, in order for reasonable reduction ratios to be

achieved, very large rolls are required in relation to the size of the feed particles. They

therefore have the highest capital cost of all crushers.

REFRENCES

PRINCIPLE S OF MINERAL PROCESSING BY GAUDIN, A. M. MINERAL PROCESSING TECHNOLOGY BY B.A. WILLS

http://www.ehow.com/list_7643968_types-roll-crushers.html#ixzz1FvXVaWHN http://www.miningonlineexpo.com/content.php/9/50/mining_high_pressure_grinding_rolls.ht

ml

http://www.ehow.com/list_7643968_types-roll-crushers.html#ixzz1FvXVaWHN

http://www.miningonlineexpo.com/content.php/9/50/mining_high_pressure_grinding_rolls.html

http://www.miningonlineexpo.com/content.php/9/50/mining_high_pressure_grinding_rolls.html


30


MACHINE STUDY OF DENVER ROLL CRUSHER AND PERFORM A

CRUSHING TEST ON A GIVEN SAMPLE.

Apparatus

Laboratory roll crusher machine

Adjustable spanner wrench

A lump of dolomite

Feed sample

A set of sieve with shaker

Tachometer

Torsion –balance/ electric balance

Procedure

Identify each part of machine. Draw a sketch and label each part

Switch on the machine and study the working of each part. Note the RPM of machine

with tachometer.

Examine the feed for its size and record the average minimum size in the feed

Adjust the set of machine with the help of the lead lump and record it. Feed the

material slowly and note how each lump is nipped between the rolls.

Switch off the machine and recover the ground product.

Transfer the ground material to a sieve set and sieve for 20 minutes.

Switch off the sieve shaker and recover the retained weights of each sieve.

Calculate the reduction ratio of the machine for test performed.

Tabulate the sieve results and plot a graph.

OBSERVATIONS

Diameter of roll (D) 10 inches = 254 mm Length of rolls (L) 6 inches = 152.4 mm R.P.M of rolls 250 to 300 Set (S) 0.25 inches = 0.635 mm Horse power of motor 8 hp Maximum size in feed (-18.85+13.33) mm Maximum size in product (-6.680+3.327) mm Specific gravity of sample( G) 2.85


31


CALCULATIONS

Reduction Ratio

Reduction Ratio =

= 18.85/6.628

= 2.82

CAPACITY

Capacity = 0.0034× N×D×W×S×G

= 0.0034 × R.P.M × Diameter × Length of the roll × Set × Specific

gravity of rock

(For maximum production we take value of R.P.M = 250)

= 0.0034×250×10×6×0.25×285

=36.3375 Ton/hour

CO-EFFICIENT OF FRICTION

Co-efficient of friction (Tan (n/2)) between the sample and rolls

Cos (n/2) = D+S/D+d

Where

n/2 = angle of nip D = diameter of roll in inch S = set = maximum size in product D = maximum size in feed Hence

Cos (n/2) = (254+6.35) / (254+18.85)

=0.95

So Angle of nip ( n/2) =17° 24’ 37" Tan (n/2) = Ø =0.3136


32


0

20

40

60

80

100

120

140

160

180

200

-1 0 1 2 3 4 5 6 7 8

Dir

ect

wei

ght

reta

ined

e

Aperture size

Series1

Linear (Series1)

Mesh

no.

Aperture

size

Direct weight

retained(g)

%age

Direct

weight

retained

Comulative

wts.

Retained

(gm)

%age

Comulative

wts.

Retained

Comulative

wts. Finer

(gm)

%age

Comulative

wts. Finer

3 6.680 145 28.37 145 26.37 366 71.62

6 3.327 179 35.02 324 36.40 187 36.59

10 1.651 51 9.98 375 73.38 136 26.66

20 0.833 28 5.47 403 78.88 82 16.04

48 0.295 54 10.567 457 89.42 28 0.0547

-65 -0.208 54 100

Total

weight=511gm


33


INTRODUCTION TO DISC MILL A disc mill is a mechanical device for the grinding of many different types of materials. Disc Mill can be used for secondary or fine crushing but its use is limited to special applications only because capacity is low and it is not suitable for all type of ores economically. For example, they are used to pulverize coal for combustion in the steam-generating furnaces of fossil fuel power plants also for glass, aluminum, concrete, plastic, coal, rock, resin, tires, and medical waste. Pulverizer machines come in a number of different forms.

CONSTRUCTION OF DISC MILL A disc mill consists of two saucer shaped discs with their surface having specially shaped grooves the depth of which reduced towards the circumference. The discs are face mounted vertically or horizontally and revolve at different speeds and in the opposite directions. In most designs of the disc is rather strongly fixed while the other flutters or gyrates during revolving. Our laboratory model has heat treated mechanical metal discs mounted vertically on revolving in a planetary manner always having a proper curvature with relation to the other which is stationary. Like other crushing machines a disc mill has not of the disc springs-loaded through a screw mechanism that helps in adjusting the set and also provides safety against un crushable lumps.

GRINDING CYCLE OF DISC MILL The material is fed through a hopper at the top and falls into the axial conic between the discs during revolving. Due to the centrifugal force the feed is pushed through the taper grooves towards the periphery and gets crushed progressively. The product is finally discharged peripherally and collected in a peripheral receptacle.

ADVANTAGES OF DISC MILL Users who need a higher level of strength and power than a hammer mill or ball milling machine can offer can use a disc mill grinder. This means they can handle harder or more durable materials like stone and steel, which may damage other types of milling equipment. They also have a relatively large capacity on average, and can accommodate large quantities of

http://en.wikipedia.org/wiki/Coal

http://en.wikipedia.org/wiki/Combustion

http://en.wikipedia.org/wiki/Furnaces

http://en.wikipedia.org/wiki/Fossil_fuel_power_plant



http://www.wisegeek.com/what-is-glass.htm

http://www.wisegeek.com/what-is-aluminum.htm

http://www.wisegeek.com/which-country-is-most-dependent-on-coal.htm

http://www.wisegeek.com/what-is-resin.htm

http://www.wisegeek.com/what-is-a-hammer-mill.htm

http://www.wisegeek.com/what-is-a-milling-machine.htm




34


material in a single batch. Compared to hammer mill or ball mills, the disc mill is also relatively quiet, and less likely to cause hearing damage to nearby workers.

DISADVANTAGE OF DISC MILL Disc mills are relatively expensive to run and maintain however, and tend to require frequent maintenance. Discs may experience wear over time as they grind various materials, which can reduce performance. The machines also produce a large amount of dust, and must be carefully ventilated when used in an indoor workspace.

MACHINE STUDY OF A LABORATORY DISC MILL AND TO PERFORM A FINE

CRUSHING TEST ON THE GIVEN SAMPLE.

APPARATUS:

Laboratory disc mill Adjustable Spanner Wrench Feed Sample A set of sieve with shaker Torsion balance /electrical balance

PROCEDURE:

Identify each part of the machine. Draw a sketch and label each part. Switch on the machine and study the working of each part. Note the rpm of the machine

with a tachometer. Examine the feed for its size range and record the average maximum size in the feed.

Adjust the set for fine crushing. Feed the material slowly and check the size of the product. Make adjustments of the set

if necessary for fine crushing. Switch off the machine and recover the product. Transfer the ground material to a sieve set and sieve for 20 mins. Switch off the sieve shaker and recover the retained weights on each sieve. Record the retained weights for each sieve. Calculate the reduction ratio of the machine for the test performed. Tabulate the sieve test and plot a graph on a suitable graph paper.


35


OBSERVATIONS

Motor power 5 hp

Motor r.p.m 1800 r.p.m

Disc r.p.m 275 r.p.m

Size of Disc 9 ½ inch (241.3 mm)

Max: feed size ¼ inch (6.35 mm)

Capacity 2 lbs/min

Sample dolomite

Feed size -2+8 mesh

Aperture size -6.680+2.362 mm

Max: product Size 6.680 mm

Weight of feed 600 gram

No. of grooves on moving disc 6

No. of grooves on stationary disc 5

RESULTS/CALCULATIONS:

A. Reduction Ratio: Max. size in the feed Max. Size in the product

= 6.35/0.208 = 30.53 B. Size analysis of the product

Mesh No.

Aperture Size (mm)

Direct wt. retained

(gm)

% Direct Wt.

retained

Cumulative Wt. retained

% Cumulative

Wt. retained

Cumulative Wt. finer

% Cumulative

Wt. finer

65 0.208 149 27.04 149 27.04 402 72.95 80 0.177 40 7.25 189 34.30 322 58.43 100 0.149 37 6.71 226 41.01 285 51.72 115 0.125 29 5.26 255 46.27 256 46.46 70 0.088 84 16.43 339 61.52 172 31.21 200 0.074 55 9.98 394 71.50 117 32.12 -200 0.074 175 28.49

Total=551


36


AN INTRODUCTION TO HAMMER MILL In these machines comminution is by impact rather than compression, by sharp blows applied at high speed to free falling rock. The moving parts are beater which transfer some of their K.E. to the ore particles are often large enough to cause them to shatter. These are increased by causing the particles to impact upon an anvil or breaker plate. Reduction ratio of the hammer mill is high as 40:1 for non abrasive material and hammer mill should not be used on ores containing over 15% silica.

CONSTRUCTION OF HAMMER MILL ROTOR The material to be reduced determines the rotor construction of the hammer mill. A series of tough armor plated steel disks or spacer plates is keyed to the extra heavily constructed shaft. Long bolts pass through their outer diameters. From these, sets of hammers are suspended. The rotor revolves within a substantial housing of exclusive cast design insuring maximum return on investment. The speed of rotor varies from 500 rpm to 3000 rpm. SHAFTS Shafts for hammer mills are made of forged alloy steel. Machined to very close tolerances from 50% to 100% oversize to prevent whipping and vibration. HAMMERS Important to consider when deciding whether to equip a machine with hammer or rings are material to be reduced, feed size, whether hard, soft, fibrous, tough, friable or abrasive, also equally important are finished product specifications. The type of the hammer selected depends also upon whether the sized product is to be uniform with a minimum of fines or pulverized with a maximum of fines. The hammers are made of high grade manganese or alloy steel, alloy steel parts being heat treated to resist abrasive wear. The hammers can weigh over 100 kg and can work on the feed size by 20 cm.


37


GRATE BARS Heavy duty grate bars are furnished when sizing hard and abrasive material like limestone, brick bats, fertilizer tailing etc. these are of rapid discharge type. Opening between the bars from 1/16 inch to 4 inch are maintained by spacing blocks securely riveted to the bars. The bars are constructed that they can be shifted around in the machine distributing the wear and getting the maximum service from each set. When a complete set of bars is installed in the machined recesses on the housing sides or bar presses against the spacing blocks of the next bar. Maintains the proper spacing when the cover is lowered the grate bars are locked into position.

HOW DOES A HAMMER MILL WORK? Hammer mills work on the principle that most materials will crush, shatter, or pulverize upon impact using a simple four step operation:

1) Material is fed into the mill’s chamber typically by gravity. 2) The material is struck by ganged hammers (generally rectangular pieces of hardened

steel) which are attached to a shaft which rotates at a high speed inside the chamber. The material is crushed or shattered by the repeated hammer impacts, collisions with the walls of the grinding chamber as well as particle on particle impacts.

3) Bar grates covering the discharge opening of the mill retain coarse materials for further grinding while allowing properly sized materials to pass as finished product.

4) Hard, heavy materials such as glass, stone or metals exit the mill via gravity. Pneumatic suction us used to assist in the discharge of lighter materials such as wood, paper or other low bulk density products.

Varying the screen size, shaft speed or hammer configuration can dramatically alter the finished size of the product being ground. For example, faster speed, a smaller screen, and more hammers result in a finer end product. GRINDING PATH The fractures pieces which can pass between the clearances of the rotor and breaker plate entre a second chamber created by another breaker plate, where the clearance is smaller, and then into a third smaller chamber. This is the grinding path which is designed to reduce flakiness and gives very good cubic particles. CAPACITY OF HAMMER MILL Large impact crusher will reduce 1.5 m top size rum of mine ore to 20 cm, at capacities of around 1500 ton/hour, although crushers with capacities of 3000 ton/hour have been manufactured. USES OF HAMMER MILL Industrial uses for hammer mills include many types of recycling operations, including producing pulp for paper production, bio-fuel production, and stone crushing. Grinding grain for ethanol production or pulverizing fruit in juice production are other possible uses for a hammer mill.

http://www.wisegeek.com/what-is-used-in-ethanol-production.htm


38


MACHINE STUDY OF HAMMER MILL AND PERFORM CRUSHING TEST ON GIVEN SAMPLE

APPARATUS:

Laboratory hammer mill Feed sample A set of sieves with shaker Torsion Balance/Electrical Balance

PROCEDURE: Identify each part of the machine. Draw a sketch and label each part. Switch on the machine and study the working of each part. Note the rpm of the

machine. Examine the feed for its size range and record the average maximum size in the feed. Feed the material slowly. Switch off the machine and recover the product and weight it. Transfer the product to a set of sieve And sieve for 20 minutes. Switch off the sieve shaker and recover the retained weight on each sieve. Recover the retained weight for each sieve. Calculate the reduction ratio of the machine for the test performed. Tabulate the sieve results and plot a graph on a suitable graph paper.

OBSERVATIONS Motor power 5 hp Motor r.p.m 1420 r.p.m Mill r.p.m 2130 r.p.m Motor pulley dia 18 cm Mill pulley dia 12 cm Grate opening 1 cm Full swing dia of shaft and hammer 35 cm No. of hammer 32 Capacity 200 ton/hour Sample dolomite Size of feed -18.85+13.33 mm Weight of feed 1 kg RESULTS/CALCULATIONS: Reduction Ratio: Max. size in the feed Max. Size in the product = 18.85/3.327= 5.66


39


Size analysis of the product Mesh No.

Aperture Size

Direct wt. retained

% Direct

Wt. retained

Cumulative Wt.

retained

% Cumulative Wt. retained

Cumulative Wt. finer

% Cumulative

Wt. finer

6 3.327 34 4.26 34 4.26 763 95.73 10 1.651 122 15.30 156 19.57 641 80.42 20 0.833 211 26.47 367 46.14 430 53.95 28 0.589 111 13.92 478 59.97 319 40.25 48 0.259 185 23.21 663 83.18 134 16.81 65 0.210 44 5.52 707 88.70 90 11.29 -65 0.210 90 11.29

Total=797


40


AN INTRODUCTIO TO ROD MILL

Grinding of materials in a tumbling mill with the presence of metallic balls or other media dates back to the late 1800’s. Historically, rod mills have been used as the first grinding stage after crushing in mineral beneficiation circuits. The rod mill product was further ground in ball mills before separation of valuable minerals from the host rock. Rod mills are similar to ball mills in appearance and in general principle. These may be defined as rotating cylindrical shells loaded with rods that grind the ore by tumbling within the shells. Rod mills are differ from ball mills in their grinding action in that the rods are kept a parted by the coarsest particles. This peculiar property of the rod mills recommends their selection where mills are used in connection with concentrating processes that fail on fine particles. Conversely, whenever flotation is to be used, ball mills are preferable. Scissoring action of the rods is an extra factor aiding to efficiency in a rod mill. They are capable of taking feed as larger as 50mm and product as fine as 300µm. its reduction ratio is 15-20:1. These are preferred to fine crushing machine when the ore is clayey or damp, thus tending to choke crusher.

Rod milling in the size range utilized is more efficient than ball milling in that the desired product is obtained at a lower cost per ton. This is due to several reasons:

1. Grinding rods do not require cascading as do ball charges, thus enabling rod mills to be operated at lower peripheral speeds than ball mills.

2. Less void spaces exist in a rod charge tan in a ball charge. Therefore, these is more grinding contact between metal an ore per surface are of media in a rod mill.

3. Lower steel consumption per ton of product occurs in a rod mill than in a ball mill due to better contact between steel and ore. The action within the rod mill causes the energy of rods to be directed to the largest sized pieces of ore. Often in a ball mill the balls grind on one another or against ore already ground fine enough.

4. Rods are more suited than balls to breaking larger pieces of ore due to their much higher weight. (Energy is equal to hall the product of the mass times the velocity squared). Larger media are capable of transmitting moiré energy per collision.

5. Grinding rods can be maintained in good working condition because broken and worn rods can be removed through the large open discharge end. Often broken pieces of rods will float out with the pulp thus avoiding entanglements.

CONSTRUCTION OF ROD MILL

SHELL

These are design to sustain impact and heavy loading, and constructed from rolled milled steel

plates and holes are drilled to take the bolts for holding the liners.

http://www.miningbasics.com/rod-mills-over-ball-mills


41


MILL ENDS

The conical heads attached to the ends of the cylindrical shell section are provided with hollow

trunnions of large diameter and narrow width for supporting the shell in suitable bearings.

MILL FEEDER Feed is introduced through a feed chute or drum feeder attached to one of the hollow trunnions. The product is discharged through a suitable opening in the opposite trunnion or through ports in the periphery of the mill shell. The trunnion, end peripheral and center peripheral discharge arrangements. Bearings

Trunnions and trunnion bearings design receive special attention. Hydrodynamic oil lubrication is generally used for Rod Mills equipped with the trunnion bearings 40” diameter or smaller. Larger sizes are arranged for full hydrostatic oil lubrication.

LINERS

Among the cast materials used for linings are Ni-Hard, chrome-molybdenum steel, and manganese steel. Rolled alloy steel plate with lifter bars is available. Rod mill liners are


42


subjected to severe impact. Premature breakage and scrap loss are reduced by correct selection of liners for the specific grinding duty.

Rod Mill Grinding Action

When the mill is rotated without feed or with very fine feed, the rods are in parallel alignment and in contact with one another for their full length. New feed entering at one end of the mill causes the rod charge to spread at that end. This produces a series of wedge shaped slots tapering toward the discharge end. The tumbling and rolling rods expend most of their crushing force on the coarse fractions of the feed material and only to a lesser degree on the finer material filling the interstices in the rod charge. The horizontal progression of material through the mill is not rapid compared to the movement of the rods and material resulting from rotation of the mill. The average particle is subjected to an action similar to many sets of rolls in series, before it is discharged.

TYPES OF ROD MILL

Rod mills are classified according to their nature of discharge. There are three main types of rod

mill, overflow, end peripheral discharge, and center peripheral discharge only the overflow mill

is in common usage.

CENTER PERIPHERAL DISCHARGE

These are feed at both ends through the trunions and discharge the ground product through

circumferential ports at the centre of the shell. Short path and steep gradient gives acoarse

grind with minimum of fines, but the reduction ratio is limited.


43


END PERIPHERAL DISCHARGE

Material is fed from one end and discharge ground product from 2nd end by means of several

peripheral apertures into a close fitting circumferential chute. This is used for dry and damp

grinding where moderately coarse products are involved.

OVERFLOW ROD MILL

This is most widely used rod mill in the mining industry, in which feed is introduced through one

trunions and discharge from other. This is only used for wet grinding. A flow gradient is

provided by making the overflow trunion diameter 10-20 cm larger than that of feed opening.


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MACHINE STUDY OF LABORATORY ROD MILL AND TO PERFORM A

GRINDING TEST ON THE GIVEN SAMPLE.

APPARATUS

Rod mill cylinder and rollers

Feed sample

Tachometer

A set of sieve

Sieve shaker

Torsion balance

PROCEDURE

Identify the each part of machine.Draw a stach and lable each part o f machine.

Switch on the machine and study each part of machine.

Note the RPM of machine with tachometer

Examine the feed for its size range and record the average size of largest lump in the

feed.note the total weight of feed.

Load the mill cylinder with its feed sample and its rod load.

Switch on and run the machine for 30 minutes and then recover the ground product.

Transfer the ground material to the set of seive by consulation and sieve for 20 minutes.

Switch off the sieve shaker and record the retained weight of each sieve.

Note the weights of the individual sieve and of the base pan.

Calculate the reduction of the machine for the test performed.

Tabulate the sieve test and plot a graph on a suitable graph sheet.

NOTE

Carefull record the weight ratio between the feed sample and rod load. portion of mill cylinder

filled and empty, keeping in view the theoretical specifications.

OBSERVATION

NAME Rod Mill R.P.M OF MILL 160 MOTER POWER ½ hp MOTOR R.P.M 710 CYLINDER DEPTH 12.25 inches ROD MATERIAL Hard carbon Steel WEIGHT OF EACH ROD 1220 grams


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SIZE OF ROD 12”×1” NO. OF RODS 3 SAMPLE Dolomite WEIGHT OF FEED 1830 grams FEED SIZE -13.33+9.423 GRINDING TIME 30 min SIEVING TIME 20 min

Mesh No.

Aperture Size

Direct wt. retained(g)

% Direct Wt.

retained

Cumulative Wt.

retained(g)

% Cumulative

Wt. retained

Cumulative Wt. finer(g)

% Cumulative

Wt. finer

4 4.699 513 28.2 513 28.1 1312 71.9

10 1.651 244 13.4 757 41.5 1068 58.5

20 0.833 158 8.7 915 50.2 910 49.8

48 0.297 247 13.534 11.62 63.7 663 36.3

60 0.250 113 6.2 1275 69.9 550 30.1

100 0.147 180 9.9 1455 79.7 37 20.3

-100 370 20.3

Total=1825

CALCULATION:

Reduction Ratio = Max. size in the feed = 13.33 = 2.84 Max. Size in the product 4.699


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AN INTRODUCTION TO BALL MILL

The final stage of comminution are performed in tumbling mills using steel balls as the grinding

medium and so designated ball mill. Ball s have greater surface area per unit weight than rods,

they having a length to diameter ratio of 1.5 to 1 and less.

Grinding balls are made of forged high carbon or alloy steel or cast steel and consumption

varies between 0.1 to as much as 1 kg/tone of new feed. Mill charge should be 40 to 50 % of

the internal volume of the mill. Ball mills are rated by power rather than capacity.

Efficiency of grinding depends upon the surface area of the grinding medium. The ball should

be as small as possible and charge should be graded such that the largest balls are just heavy

enough to grind the largest and hardest particles in the feed.

An internal cascading effect reduces the material to a fine powder. Industrial ball mills can

operate continuously, fed at one end and discharged at the other end. Large to medium-sized

ball mills are mechanically rotated on their axis, but small ones normally consist of a cylindrical

capped container that sits on two drive shafts (pulleys and belts are used to transmit rotary

motion).

CLASSIFICATION OF BALL MILL

Ball mills are classified by the nature of the discharge. These are

Trunion overflow mills

Grate discharge mills

GRATE DISCHARGE MILL

This m ill type embodies the principle of steep pulp gradient. Quick discharge operation. A grate

assembly at the discharge en d of the mill permits retention of a higher ball charge (up to 50%)

than is possible in an overflow mill which has a practical limit of around 40%. Behind the grates

is a lifting compartment which picks up the ground material as it passes through the grates and

transports it out of the mill. grate mill will draw more power and produce more product than its

overflow counterpart of the same dimensions.

This quick removal of ground material reduces overgrinding to a minimum. The fact that all

material leaving the mill must pass though the grates and in so doing must become enmeshed

in the ball charge minimizes the possibility of tramp oversize material passing though the mill

without being ground. In dry ball mill grinding, a grate mill should be used because dry material

will not overflow as well as wet material. Thus savings on power consumption are available by

http://en.wikipedia.org/wiki/Pulleys

http://www.miningbasics.com/how-grate-discharge-ball-mill-works


47


selecting the grate design. The grate mill by virtue of its steeper pulp gradient has a more rapid turnover

of material than its overflow counterpart.

TRUNION OVERFLOW BALL MILL

In this type of mill the balls are kept in the mill, by keeping the top of the ball charge below the

level of the trunnion opening. When operating an overflow mill with a higher charge escaping

balls are returned to the mill by a reverse spiral in the trunnion liner or are restrained by a ball

retaining grate.


48


MACHINE STUDY OF DEN VER LABORATORY BALL MILL AND TO

PERFORM A GRINDING TEST ON THE GIVEN SAMPLE

APPARATUS

Denver ball mill

Feed sample

Tachometer

A set of sieve

Sieve shaker

Torsion balance

PROCEDURE

Identify the each part of machine. Draw a sketch and label each part o f machine.

Switch on the machine and study each part of machine.

Note the RPM of machine with tachometer

Examine the feed for its size range and record the average size of largest lump in the

feed. Note the total weight of feed.

Load the machine with a suitable ball rod and feed material.

Switch on and run the machine for 30 minutes and then recover the ground product.

Transfer the ground material to the set of sieve by consulation and sieve for 20 minutes.

Switch off the sieve shaker and record the retained weight of each sieve.

Note the weights of the individual sieve and of the base pan.

Calculate the reduction of the machine for the test performed.

Tabulate the sieve test and plot a graph on a suitable graph sheet.

NOTE :

Carefully record the weight ratio between the feed sample and rod load. Portion of mill cylinder

filled and empty, keeping in view the theoretical specifications.

OBSERVATION

NAME Ball Mill

R.P.M OF MILL 42

MOTER POWER ¼ hp (Gear Reducer)

MOTOR R.P.M 1425


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CAPACITY 4 kg/hr

MATERIAL OF BALL Alloy Steel

DRUM MATERIAL Cast Iron

TOTAL WEIGHT OF BALLS 3550 gram

SAMPLE Dolomite

WEIGHT OF FEED 1775 gram

FEED SIZE -13.33+9.423

GRINDING TIME 30 min

SIEVING TIME 20 min

No. of balls Size of ball(cm) Weight of each ball Total weight

2 5.5 685 1370 4 4 275 1100 8 2.5 75 600

16 1.9 30 480

Mesh No.

Aperture Size

Direct wt. retained(g)

% Direct Wt.

retained

Cumulative Wt.

retained(g)

% Cumulative

Wt. retained

Cumulative Wt. finer(g)

% Cumulative

Wt. finer

4 4.699 1069 60.4 1069 60.4 701 39.6

10 1.656 160 9.1 1229 69.5 541 30.5

28 0.589 99 5.6 1328 75.1 442 24.9

48 0.297 133 7.5 1461 82.6 309 17.4

60 0.250 49 2.8 1510 85.3 260 14.7

100 0.147 75 4.3 1585 89.5 185 10.5

-100 185 10.5

TOTAL=1770

CALCULATIONS:

Reduction Ratio = Max. size in the feed = 13.33 = 2.84 Max. Size in the product 4.699


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STANDARD SIEVE SERIES

Product sieving is now an essential requirement in nearly all industries. To obtain a quality-controlled end product not only required diligent ingredient choice but careful handling and processing. Removal of any substandard or unwanted matter is therefore a prime requirement.

For all laboratory sieve analysis standard sieve series are employed. Different sieve series different from one another in their actual mesh dimensions for the same mesh numbers. In the U.S.A American standard sieve series are Taylor standard sieve series are used. The British, French and German use their own standard sieve series while from Japan OGAWASEIKI standard sieve series are available. A mesh number is number of apertures per linear inch, e.g. a 100 # sieve has one hundred

apertures per linear inch. A square inch of the 100 # screen surface accordingly has 10000

apertures. Depending upon the size of the wire the actual size of the apertures for a varies

particular mesh number from one standard series to another, and generally this is the only

difference between different series. Total mesh numbers in a series may be upto 28 or more

and the series follows a Geon metrical progression with a ratio of 2 or its multiples starting a

200 # sieve.

A laboratory sieve with some variations generally measures about 8 inch in Dia and 205 inch

deep. The frame is rimmed at the top and screen cloth rigidly mounted at its bottom. The frame

is labeled with the particular # no. with notation of the standard sieve series. The actual

dimension of the aperture in mm or microns is also given on the label. The sieve can be

attacked together because they fit into one other very easily.

For a particular sieve test the required sieves are stacked together in a prope order so that the

coarsest is at the top and the finest at the bottom. A Pan is fitted below the finest sieve and a

lid at the top of the series and the set placed in sieve shaker. After filling the top sieve with the

sample to be tested. Shaking in allowed for a suitable time then the set is removed and opened

for weighing different size fractions.


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STUDY OF LABORATORY WOVEN WIRE STANDARD SIEVE SERIES AND TO

PERFORM A DETAILED SIEVE ANALYSIS TEST ON A BALL MILL PRODUCT SAMPLE.

EQUIPMENT /APPARATUS REQUIRED:

Laboratory standard sieve series set of 18 sieves or 12 sieves.

Ro-tap sieve shaker.

Torsion balance.

Set of brushes for cleaning the sieves.

Timer.

Sample to be analyzed.

Sample trays 19 Nos.

PROCEDURE:

Study the sieves for their size (dia. & depth), mode of construction, printed mesh numbers and

aperture size on individual sieves.

Record the mesh numbers and aperture sizes of all the sieves in the set in a decreasing size

order.

Study the construction and operation of the ro-tap sieve shaker.

Study the timer connected to the sieve shaker.

Transfer the weighed sample to the top sieve in a set of first 6 sieves. Fit the lid and the pan to

the sieves and loaded in the shaker. Adjust the timer for 20 minutes and the switch on the

shaker.

After 20 minutes switch of the shaker, remove the sieve set dismantle and weigh the retained

sample on each sieve and record the weights.

Transfer the contents of the pan to the next set of 6 sieves and repeat the process.

Transfer the pan contents of the second set to the third set of engaged of sieves and repeat the

process.

Record all the weights retained and the weight of the last under size in the series.

Clean the sieves with the help of bushes and put them back in the rack carefully. Take care not

to damage any screen cloth while handling and cleaning.

Tabulate the results properly and also draw a suitable graph of the results.

OBSERVATIONS:

DIAMETER OF THE SIEVES IN INCHES 8”

DEPTH OF THE SIEVES IN INCHES 2.5”


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NO. OF SIEVES FOR SIZING 6

WEIGHT OF FEED 1 KG

MOTOR POWER 0.25 HP

MOTOR SPEED 1425 RPM

RESULTS / CALCULATIONS:

Mesh no.

Aperture mm

Direct weights Cumulative weights retained

Cumulative weights passed

Actual weights (grams)

%age weights


%age weights


%age weights

65 0.208 48 4.93 48 4.93 926 95.07 80 0.177 45 4.62 93 9.55 881 90.45 100 0.149 147 15.09 240 24.64 734 75.36 115 0.125 79 8.11 319 32.75 655 67.25 170 0.088 208 21.35 527 54.11 447 45.89 200 0.074 123 12.63 650 66.73 324 33.27 -200 325 33.26

Total = 975


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AN INTRODUCTION TO STANDARD SCREEN

Screen is name which is given to a number of things, one of these things is any such a

vessel/utensil integrally consists of a perforated surface which is used for sifting to separate

particles of a desired size-grade from a multitude of sizes contained in a given material. In the

mineral dressing terminology, this act of sifting is called screening and the vessel is screen.

TYPES OF SCREEN SURFACES

Woven wire (square openings)

Punch plates (circular, square or slot like openings)

Parallel rods (slot like openings)

Screening is the most important method of sizing both industrially as well as in laboratory but

with varying limitations. The second most important method is classification, Elutriation and

sedimentation being a part of it.

In industry are employed larger and larger screening/classification plants for and more output,

where as in laboratory work standard screens called “ test sieves” and mini model classifiers for

more and more accuracy.

Material’s size range within which it’s considered an industrial scale screen is effective for

efficient sizing is from several inches to 1 mm generally and in special cases of materials

requiring the products must be dry, like talcum powder, Al powder, cement etc. down to 200

mesh.

TYPES OF SCREENING MACHINES

The machines called ‘automatic screens’ are of two basic kinds,

The Stationary Screens

Moving Screens.

STATIONARY SCREEN

A stationary screen has the screening surface in sloping position and idle on which the feed

material is moved by an automatically driven element from outside and gets the chances to

pass across the openings, whereas in the case of a moving screen, the screen surface itself

moves and causes the feed material pass across the openings.

Again moving machines are of several types including moving grizzlies, trammels, shaking

screens, and a modern type named vibrating screens. The vibrating screens for its extensive


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efficiency and use have bypassed all other types and attained the status of most of most useful

screens for all types of permeable materials.

VIBRATING SCREENS

Vibrating screens are the most important screening machines for mineral processing

applications. They handle material up to 25 cm in size down to 250 microns. Their main

application is in the crushing circuits where they are required to handle material ranging, in

general, 25 cm to 5 mm in size.

They can work at low slopes and little headroom. In multiple deck systems the feed is

introduced to the top coarse screen, the undersize falling through to the finer screens, thus

producing a range of sized fraction.

The vibrating screens are vibrated mechanically or electromagnetically and both give equally

good sizing results.

In our laboratory, we have one tiny model of mechanically vibrating industrial screen and one

of the electromagnetically vibrating screen. Mechanically vibrating screen has its trade name

“Denver Dillon” provided with 2 decks of different aperture sizes.

MECHANICALLY VIBRATING SCREENS

A mechanically vibrating screen may consist of a single deck

(screening surface) are more than 1 decks arranged one over the

other, with a base frame carrying through heavy coil springs and

screen frame or frames rigidly fastened to the vibrating mechanism.

The vibrating mechanism consists of a shaft fitted with an eccentric

and the motion is thus transmitted mechanically. The screens are

removable and any desired one’s can be fitted in the frame.

A single deck screen gives two products, oversize (coarser than the screen opening) and the

undersize passed through it. A double deck screen will give three products, oversize of the top

screen, undersize of the bottom screen, and middling product that has passed through the top

screen but retained on the bottom screen. Provisions are made for collecting the products

separately.

ELECTROMAGNETICALLY VIBRATING SCREENS

Electromagnetically vibrating screens are generally called hummer

screens and are truly electrically vibrated. Vibration is obtained from


55


the action of electromagnet on an armature. The upstroke is suddenly interrupted when the

armature hits the striking block but the down stroke is not so interrupted. The differential

motion results in constant un blinding of the screen. It further simulates jigging and causes the

particles to stratify, the coarsest particle at the top and the finest next to the screen surface.

This helps in the discharge of coarser/oversize particles quickly off the screen surface and

allows more chances to the fine particles to pass through the screen.

The screen consists of a coarse backing screen over which the requisite fine screen is laid but

kept in tension by suitable tensioning devices. The fine screens can be easily replaced when

necessary.

A low frequency alternating current or a rectified current is normally used. For finer or damper

materials a relatively higher frequency current is used. Hummer can also be multi-deck screen.

Gyratory screens

This type of screen which imparts gyratory motion throughout the

whole screen cloth is becoming widely used for fine screening

applications, wet or dry, down to 40 microns. The basic components

consist of a nest of sieves supported on a table which is mounted on

springs on a base; suspended from beneath the table is a motor

with double shaft extensions, which derives eccentric weights and in

doing so effects horizontal gyratory motion. Vertical motion is

imparted by the bottom weights, which swing the mobile mass

about its center of gravity, producing a circular tipping motion to the screen, the top weights

producing the horizontal gyratory motion.

Ball trays may be fitted below a screen assembly to reduce blinding.

PROCEDURE:

Identify each part of each of the both machines. Draw sketches and label each part of the both.

Make two representative samples of the given feed by the method of ‘coning and quartering’ or the ‘Rifflers’

First feed 1 sample to the hummer screen, slowly, with the tilt suitably adjusted, so that the material gets sufficient time to pass through the screen cloths.

Switch off the machine and collect the oversize and the undersize products.

Weigh the products and calculate weight percentages.


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Secondly, feed the second part of the sample to the Denver Dillon vibrating screen (which has two screen decks of different mesh sizes and gives three products), and proceed as done in the 1st case.

OBSERVATIONS

FEED WEIGHT 500 G

FEED SIZE -4 + 48 #

APERTURE SIZE -4.699 + 0.295 MM

SAMPLE DOLOMITE

Characteristics Hummer screen (single deck)

Denver Dillon screen (double deck)

Size of the screen 22”*30” i. (12”*24”) ii. (12”*24”)

Mesh no. 10 # i. 10# ii. 20#

Frequency of vibration 3000 vib/min 1200 vib/min

RESULTS AND CALCULATIONS

SINGLE DECK

Oversize weight % weight of oversize Undersize weight % weight of undersize

214.5 42.9 293 58.6

DOUBLE DECK

Oversize weight % weight of oversize

Middle size weight

% weight of middle size

Undersize weight

% weight of undersize

109 21.8 136 27.2 170 34


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Documents

Mineral Processing Lab Assignments