Lecture A1

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CHPR4405: P ARTICLE M ECHANICS AND SOLIDS H ANDLING

WHY IMPORTANT IN CHEMICAL E NGINEERING PROFESSION ?

INDUSTRIES THAT INVOLVE IN PARTICULATE MATERIALS PROCESSING ARE MANY SUCH AS: Crude Oil and Gas Refining and Petrochemicals Foods and Beverages Pharmaceuticals Biotechnology tissue engineering, vaccine production semiconductor and electronic nanotechnology Paints, papers and coating mining and minerals processing

water treatment and water quality monitoring

Mineral processing and Oil and Gas Proceessing industries are very large and hence very importantin WA employing many chemical engineers

Mineral Processing: crushing and grinding jaw crusher, Sag Mill hydrometallurgy flotation, leaching, electrowinning, solvent extraction Pyrometallurgy smelting Other operations slurry thickening and sedimentation, pumping and pipeline transportation


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Micro Brewery


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Gold Processing carbon-in-pulp (CIP) process


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Gold ore

LEACHING

ADSORPTION ON ACTIVATED CHARCOL LOADED CHARCOL EFFLUENT

STRIPPING BARREN SOLUTION POND

STRIPPING CHARCOAL STRIPPING SOLUTION

R EACTIVATION

ELECTROLYTIC DEPOSITION

ELECTROLYTE

GOLD CATHODE SMELTING DORE BULLION


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Minerals

Naturally occurring compounds with a commercial value

Gold and Platinum : found principally in nature in metallic form

Silver, copper & mercury: in the form of sulphides, carbonates chlorides

Minerals namePbS (galena or lead sulphide)

ZnS ( sphalerite)

SnO 2 (cassiterite)

Cu 2S (chalcocite )

FeS 2 (pyrite)

Metallic ore processing converts minerals to metals such as Cu, Pb, Zn, Sn, Ni


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Ore body

Defined as an accumulation of minerals in sufficient quantity as to be capable ofeconomic extraction.

Values minor component, valuable minerals

Gangue major component, waste mineral

Factors which controls the suitability of a deposit for economic mining andprocessing:

Location and size of deposits

Grade of Ore (metal content and distribution) Financial aspects Mining cost Cost of ancillary services Amenability of ore to treatment Demand and value of metal


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Mineral processing involves the physical separation of the valuable minerals fromthe gangue to produce a concentrate of value; and tailings containing mostlygangue.

Mining

Ore

Mineral processing

Concentrate Tailing(value) ( gangue)

Extractive Metallurgy

Metal


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Fundamental Operations in Mineral Processing

a) liberation of value minerals from gangue

comminution(size reduction)

crushing

grinding

b) separation of liberated value from gangue by using their physical and chemicaldifferences which includes:

specific gravity optical, radioactive hydrophilic, hydrophobic, wetability magnetic electrical conductivity


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Liberation

Free values from the gangue material by size reduction of the ore

Ore

Crusher(+)

Screen (-)

Grinding (wet)

(+)Classification(-)

Separation

Concentrate middling Tailings


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Degree of liberation =

(amount of free value minerals in the comminuted ore)/ (total value mineral in thetotal ore)

Concentration (eg flotation)

Separation of liberated values from the gangue

Comminution

Separation

Concentrate Tailings

Extractive Metallurgy

Metal


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Recovery

=(metal recovered from the concentrate)/ (total metal in the ore)

Grade or Assay mineral content

Recovery

Grade of concentrate 1/(cost of extraction)

Low grade ore required high degree of recovery for the operation to beeconomically feasible.


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Crushing, Grinding and Sizing

Primary Crushers

Heavy duty machines, reduce runs of mine ores (1.5m) down to transportable feed tosecondary crusher (10-20cm)

Types:

Jaw crushers Gyratory crushers

Jaw Crusher

Features two plates set at an acute angle to each other, one jaw is pivoted sothat it swings relative to the other fixed jaw.

Operation of a Blake Crusher

1. The swinging jaw is pivoted from the top, moving quickly at first then more slowlywith increasing power towards the end.

2. The minerals fed are crushed. The fragments fall but their fall is arrested at a newrest position in the jaw where it is gripped and crushed again. This continues allthe way to the discharge area of the crushed.


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3. the flywheel attached to the drive is necessary to store the energy on the idlinghalf of the stroke and delivers it on the crushing half.

4. Angle between the jaws < o26

5. Maximum amplitude of swing of the jaw or ``throw 1-7cm

6. Speed of swinging jaw 100-350 rev/min

7. Feed capacity 725 ton/hr

8. Maintenance is easy

SECONDARY CRUSHER

Reduces particle from size


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Cone Crusher

Cone is not suspended as in gyrotory crusher but is supported in a curveduniversal bearing

The bowl or crushing shell flares, providing an increasing cross sectional areatowards the discharge end. This prevents choking, thus high capacity is possible(1100ton/hr 3000ton/hr)

Throw 5x primary crusher (1-7cm)

Operates at higher speed (300-500rev/min)


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Grinding (wet)

Sag Mill (a ball mill) with large diameter to length ratio

Inside of Sag Mill picture of a Sag Mill

Principle of Sag Mill grinding


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produce a slurry with the desired degree of minerals liberation use 80 % of materials passes through a certain size (P 80 ) as the indicator slurry with particle size distribution ranging from a few to several hundreds

micron feed stock for flotation operations.

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Lecture A1