Design Criteria and Guidelines for Surface Infrastructure Mechanical and Structural

7/24/2019 Design Criteria and Guidelines for Surface Infrastructure Mechanical and Structural

1/68


2/68

AATC DESIGN CRITERIA AND GUIDELINES FOR SURFACEINFRASTRUCTURE - MECHANICAL & STRUCTURAL

IMPLEMENTATION 11/22/2013

DOC NO AATC000859

CONTENTS

Page

1 AIM 4

2 DEFINITIONS 5

3 PROCESS DESIGN CRITERIA 6

3.1 Material Characteristics 6

4 MECHANICAL DESIGN CRITERIA 7

4.1

Design Codes and Standards 7

4.2 Surface materials handling systems General requirements 7

4.3 Environmental Aspects 13

4.4 Standardisation 13

4.5 Belt Conveyors 14

4.6 Chutes 30

4.7 Mechanical Design General Requirements 32

4.8 Fire protection 36

4.9 Pipework and Valves 36

4.10 Platework and Lining 47

5 STRUCTURAL DESIGN CRITERIA 52

5.1 Plant Buildings and Structures 52

5.2 Conveyor Structures 53

5.3 Walkways, access, platforms and flooring 54

5.4 Cladding of structures 55

5.5

Civil 57

5.6 Corrosion Protection 57

6 INTERFACES 60

6.1 Civil 60

6.2 Electrical Engineering 60

6.3 Instrumentation 61

7 REFERENCES 62

7.1 AA Standards and Specifications: 62

Refer to the AATC Document Management System for the latest version of the document. Copyright resides with thecompany.

Page 2 of 68


3/68



DOC NO AATC000859

7.2 National Standards and Specifications 63

8 REVISION HISTORY 64

9

APPENDICES 65

9.1 Appendix A: Preferred Vendor List 65

9.2 Appendix B: Standard Drawings 66


Page 3 of 68


4/68



DOC NO AATC000859

1 AIM

The purpose of this document is to provide generic design criteria and guidelines for AATC

surface infrastructure projects related to the Mechanical and Structural Steel Engineeringdisciplines. Certain basic civil aspects which directly impact on the mentioned disciplines arealso covered but not from a design perspective.

Underground systems are covered under the AATC Underground Conveyor Design Guidedocument number AATC000860.

The intent of the document is not to present detailed design information for each component andsystem, but rather to outline guidelines and certain mandatory requirements not contained inspecifications. Any particular information not contained herein must be developed duringdetailed design stage to support equipment and erection specifications.

This document shall be read in conjunction with the relevant Anglo American Specifications asquoted, which shall be issued as part of the equipment and/or contract enquiry documents.

In project specific cases where the need arise to deviate from any item in this document aconcession must be submitted to and approved by the Engineer in writing.

Where an item is specified with a note stating or equivalent, the Engineer shall be requested inwriting to grant permission to use such an alternative.


Page 4 of 68


5/68



DOC NO AATC000859

2 DEFINITIONS

Term Definition

AATC Anglo American Thermal Coal

AFRS Anglo American Fatal Risk Standard

APW Anglo Projects Way

Approved Approved by the Engineer in writing or signature

BMH Bulk Materials Handling

BS British Standard

BS EN British Standard European Norm

CEMA Conveyor Equipment Manufacturers AssociationCMA Conveyor Manufacturers Association

DMR Department of Mineral Resources

Engineer AATC Discipline Engineer assigned to the project

ESS Electronic Soft Starter

FELFront End Loading of Project Phases (Refer to APWdocumentation)

HAZOP Hazard And Operability Study

ISO International Standards Organisation

MCC Motor Control CentreOEM Original Equipment Manufacturer

PFD Process Flow Diagram

P & IDs Piping And Instrument Diagrams

PLC Programmable Logic Controller

PSD Particle Size Distribution

SANS South African National Standard

SIB Stay in Business

ROM Run of mine

VSD Variable Speed Drive


Page 5 of 68


6/68



DOC NO AATC000859

3 PROCESS DESIGN CRITERIA

3.1 Material Characteristics

3.1.1 General design parameters

The table below indicates the design parameters to be used in all material handlingsystems. Material flow tests should ideally be conducted during FEL 2 so that the designdata is available when FEL 3 commences.

DutyThe plant and equipment shall be designed to operate 24 hours a day, 7days a week; with one 8 hour maintenance shift a week.

ROM material

The nature of the reserve must be understood i.e. virgin reserves versuspreviously undermined areas.

Consideration must be given to previously undermined operations wherethe top size of lumps cannot be accurately controlled and instantaneousslugs of 100 % stone may occasionally occur in the feed stream. Whereweathered coal exists, the total instantaneous throughput tonnage maybe fine material.

When designing systems, the scale of the operation must be consideredsince design approach and methodology are not the same for a 0.5 MTAmini-pit as opposed to a 20 MTA operation.

Contamination Previously undermined reserves may contain a considerable amount oftimber and tramp metal.

Raw coal PSDThe particle size distribution can be considered typical of open castoperation but confirmation from metallurgy is prudent. It is not uncommonto encounter 2 m top size lumps.

Bulk density

(volumetric)Volumetric calculations to be based on lowest anticipated bulk densityunless a correction factor is applied in the calculations.

Bulk density (mass)Power calculations to be based on highest anticipated bulk density unlessa correction factor is applied in the calculations.

Total moisturecontent

Average 12 %Dry season 8 %Wet season 15 %(Guideline only, reserve specific)

Angle of repose 38 (Guideline only project specific data required for detail design)

Bulk densities

Raw coal : 900 to 1300 kg/m3

Product : 900 to 1100 kg/m3

Discards : > 1100 kg/m3

Guideline only - For specific project information refer to the bulk solidsflow reports or confirm with AATC metallurgy.

Table 1 General Design Parameters


Page 6 of 68


7/68



DOC NO AATC000859

4 MECHANICAL DESIGN CRITERIA

4.1 Design Codes and Standards

4.1.1.1 The design and construction of all works shall be carried out in accordance with allapplicable laws, regulations and standards. This document is regarded as a guidelinewith certain mandatory requirements. Applicable standards which are not listed must beincluded by the designer or supplier.

4.1.2 Anglo American Specifications

4.1.2.1 The list of Anglo American Specifications referred to in this document is provided inSection 7 References.

4.1.3 Applicable Codes, Standards, Acts and Regulations

4.1.3.1 Unless specifically stated otherwise, designs shall be based on the applicable parts ofthe latest revision of the Codes, Specifications, Standards, Regulations and otherdocuments. The list of the codes, specifications, standards and regulations referred toin this document provided in Section 7 References. In addition, the design must complywith local legislation and regulations as stipulated by the DMR.

4.1.3.2 In the event of conflicting requirements, the most stringent will apply.4.1.3.3 For conveyor designs, ISO 5048 will take preference over CEMA requirements.4.1.3.4 The following protocol will be used where specifications are required:

1) Available Anglo American specifications must be used.

2) If no Anglo specifications are available, refer to the most relevant SANSspecification.

3) If no SANS specifications are available, international specifications recognisedwithin the industry may be applied.

4.2 Surface materials handling systems General requirements

4.2.1 General

The layout of materials handling systems must be conducted in view of an optimalbalance between operational costs and capital expenditure.Where the implementation of new technology is considered viable, a trade off studymust be done against the conventional approach.

Designs must be carried out with consideration for the reduction of fines generation.

4.2.2 Tips General

The layout of tips must be such that free access with mobile cranes is possible from bothsides.The topography of the location can often be used to minimise the ramp height and excavationdepth. However, free drainage is mandatory.On certain large and more complex tip configurations, typically associated with previouslyundermined reserves, an overhead crane may be required. On these installations only roof

sheeting will be required.


Page 7 of 68


8/68



DOC NO AATC000859

4.2.3 Dust hood

Passive dust suppression is mandatory on all new tip installations. The passive systemmay be aided by the intermittent use of a spray system as and when required.

The volumetric design of the hood structure is somewhat specialised but essentially itneeds to provide enough volume so that the displaced air, as a consequence of thetipping operation, can settle down such that dust pollution is minimised.

Installations must be equipped with used fire retardant conveyor belt installed in aspecific internal baffle arrangement to enable dust particles to settle out.

The ratio of the dust hood width/truck width must fall within a range of 1.8 to 2 in order toensure easy truck manoeuvrability and to avoid mechanical damage. Columns must

ideally be integrated with the wing walls and bin structure to eliminate structural damage.

The walls of the bin must be raised to prevent damage to the sheeting by large rollinglumps when the bin is full or where grizzly cleaning operations are anticipated.

Safe access to the roof is required for the maintenance of lighting etc.

The orientation of the hood must ideally be such that the prevailing wind direction istowards the tipping face i.e. into the hood.

4.2.4 Jockey SlabThe jockey slab must be equipped with cast-in rail liners to facilitate cleaning operations.

The ideal height of the wheel stopper must be 67% of the wheel diameter. Specialconsideration is required where different truck types are anticipated. The steel coverplate must be submerged well into the concrete such that it cannot be lifted duringcleaning operations by a front end loader. Avoid any ledges that can initiate materialbuild up.

Where a concrete bin is utilised, the jockey slab will be integrated with the wing wallsand bin structure. For a steel bins however, the jockey slab will be independent.

4.2.5 Tip static grizzly

The viability of using a static grizzly depends on the specific operations. The guideline isto equip mini-tips with low throughput tonnage with a static grizzly to ensure that smaller,cost effective equipment can be selected.

The consideration for a grizzly must be done within the context of downstreamequipment selection.

The grizzly aperture is reserve specific but within AATC 1.2m x 1.2m is commonly used.

Static grizzlies are not permitted on large operations where previously undermined areas


Page 8 of 68


9/68



DOC NO AATC000859

will be mined. The philosophy is that large lumps can be removed safer at an inspectionfeeder at a lower level in the tip, which is equipped with an overhead crane.

Grizzly bars and support structures must be designed to safely withstand the impact

energy associated with the tipping operation and where applicable, the hydraulic rockbreaker.

4.2.6 Tip static grizzly cleaning operations

It is not permitted to use a fixed pecker in conjunction with a dust hood.

The use of a TLB may be functional on mini-pit operations but on larger tips, the reachmay be insufficient. A track mounted excavator, equipped with a hydraulic hammer maybe required.

On mini-pit operations, it may be more efficient to remove and stockpile oversize rockinstead of attempting it through the grizzly.

4.2.7 Tip bin

The volume of the tip bin is generally taken as 2 to 3 times the capacity of the haulingtrucks but must be justified by simulation or calculation.

Steel bins should only be considered for an anticipated mining life of less than 15 yearsbecause of corrosion considerations. All other installations must be constructed out ofconcrete.

Concrete bin constructions can be integrated well with the dust hood, wing walls andwheel stoppers.

Concrete bins must be equipped with casted in rail liners.

Discharge arrangement designs should be based on mass flow system. Appropriatematerial release angles to be applied.

4.2.8 Tip feedersThe draw off pattern achievable is a function of the geometry of the interfacing platework. The design must be such that tipping space is continuously created at the tippingface of the bin.

Big lumps must specifically be catered for on large operations. However, at smalloperations, a trade off is required to ensure that capital cost remains at an acceptablelevel.

Where previously undermined areas are included in the mining plan, the preference is touse a conventional apron feeder. Apron feeders are generally orientated in line with the

tipping face such that dribbling is collected on the clearance conveyor.


Page 9 of 68


10/68



DOC NO AATC000859

Flight bar feeders may be used on mini-tips and larger operations where virgin areas aremined but the bin interface requires careful consideration.

The orientation of these feeders i.e. parallel or perpendicular to the tipping face is project

specific.

A perpendicular arrangement provides good maintenance access but the tail end of thetip clearance conveyor cannot be utilised as a spillage conveyor. A parallel configurationis therefore preferable when using a conventional apron feeder.

A perpendicular arrangement is usually preferable when using a flight bar type feederbut not mandatory.

4.2.9 Grizzly and observation feeders

Grizzly feeders are generally associated with tips used at previously underminedreserves where jaw crushers are installed. Large tramp metal chunks, oversize lumpsand timber can be removed with an overhead crane from the observation feeder deck.Safe access onto the observation feeder deck is a key design consideration. Thedecision to utilise these feeders are project specific.

4.2.10 Rock breaker

Rock breakers are generally associated with tips equipped with observation feederssuch that large lumps can also be broken at sizer or crusher feed-ends.

The guideline rating for the hydraulic hammer is 2000 Joule.

4.2.11 Primary crushing

Jaw crushers are considered more robust than mineral sizers and are thereforepreferred where previously undermined reserves are mined. The large lumps associatedwith this type of operation generally lead to the selection of the largest crusher availableon the market i.e. 80 x 60

Where virgin reserves are mined, mineral sizers are preferred.

The preferred feed configuration is such that the feed stream lands parallel to the sizershafts such that fines can easily pass through the sizer without being scrolled to thesides. A perpendicular feed arrangement is also possible but will result in uneven wearand may lead to throughput constraints when the sizer is operating close to its capacitylimit.

4.2.12 Secondary crushing

A scalping operation between the primary and secondary crushers or sizers will usuallyenable the selection of a smaller secondary machine with reduced wear andmaintenance.

The removal of tramp metal is problematic where the secondary sizer is positioned


Page 10 of 68


11/68



DOC NO AATC000859

directly below the primary sizer. This configuration must be avoided.

4.2.13 Tertiary crushing

Although the throughput tonnage processed by the tertiary crushers is often lower thanupstream crushing operations, tertiary crushers often work the hardest and are oftenwhere excessive wear, throughput and oversize problems occur.

Special consideration must be given to the nature of the operation. During the rainyseason, when wet material is processed, throughput problems may occur if the sizer ismarginally selected.

It must be noted that where a guaranteed product size must be delivered i.e. Eskomproduct, mineral sizers are not suitable on its own without a final screening operation. Asinternal wear occurs, oversize material will be encountered. Granulators are generally

utilised where stringent final product size specifications is stipulated.

4.2.14 Tramp metal removal

The most effective tramp metal removal configuration is where the magnet is positionedabove a material trajectory. Conventional overband magnets are however oftensufficient. Where excessive amounts of tramp metal are anticipated, the magnet shouldbe positioned at a perpendicular transfer. This configuration will also make the removalof long rails and timber logs possible. Where magnets are positioned above a transfer,stainless steel pulleys are usually only required for belt speeds below 2 m/s.

4.2.15 Rotary breakers

A rotary breaker should not be used as a primary crusher on opencast applications. Theimpact energy associated with large lumps is problematic.

A concrete support structure is preferred. A conservative structural design approach isadvisable.

A scalping operation upstream of the rotary breaker should be avoided unless the usethereof can be justified.

4.2.16 Silos and bins

The general guideline is to use steel for the construction of bins with a capacity of lessthan 500 ton and concrete for silos in excess of 1000 ton. The range between 500 and1000 ton may be constructed out of steel or concrete based on economical or otherconsiderations.

Where the anticipated life of the project exceeds 20 years, concrete construction ispreferable.

Silo diameters commonly used includes 13, 16, 20 and 22 m.

Where concrete roofs are used on silos, dust explosions must be catered for by means


Page 11 of 68


12/68



DOC NO AATC000859

of explosion panels.

Silos and bins are generally designed for expandable flow conditions in the upper regionwith mass flow conditions at the discharge hopper.

4.2.17 Silo and bunker trade-offs

Although several project specific considerations will influence the selection, Table 2below is to be used as a guideline.

Surge / storage struc ture Approx capacity range (m3) Comment

Bin, steel Up to 1 000Project requirements maydictate concrete construction.

Silo 1 000 to 6 000Consider bunker for > 5 000m3

Silo, rail load out up to 10 000Bunker with rail load out binmust be evaluated.

Bunker, (RE C) 2 500 to 15 000Project specific constraintsmay rule (RE) option out.

Bunker, longitudinal

RC / RC P / RE L

> 6 000

Where:

RC = Reinforced concrete

RC P = Reinforced concrete with pre-cast elements

RE C = Reinforced earth, circular

RE L = Reinforced earth, longitudinal

Whenever the required surge or storage capacity is close to the threshold values indicatedabove, a trade-off study would be required unless an option can be ruled out because ofspecific project requirements or constraints.

Table 2 Selection guideline for silos & bunkers

4.2.18 Stockyards and equipment

The possibility of future expansion must be considered when conducting layouts.Stockyards should, where possible, not be located within a rail loops unless sufficientspace is available for future expansions.

Where possible, stockyard by-pass conveyors must be included.

4.2.19 Escape access

The need for escape access, cross overs at conveyors and especially parallelconveyors where personnel can be entrapped in case of fire, must be determined by risk

assessment.


Page 12 of 68


13/68



DOC NO AATC000859

4.3 Environmental Aspects

4.3.1.1 Environmental aspects are regulated by local Legislation. Items listed below merelyhighlights some important considerations directly related to designs.

4.3.1.2 All designs shall be carried out such that the impact that mining operations have on theenvironment is minimised. Of particular concern are water, dust and noise pollution.

4.3.1.3 All water that arises within the conveyor area shall be contained and channelled to thepolluted water handling system.

4.3.1.4 Overland conveyors transporting material outside the boundaries of the polluted areamust be equipped with belt turnovers at the head and tail to avoid material carry backalong the conveyor. Turnovers are problematic on wide conveyors. Overland conveyorsused for AATC projects are generally less than 1500 mm wide such that turnoverdesigns are possible.

4.3.1.5 Generation of dust shall be strictly controlled by avoiding degradation of the coal andthe dust that is generated shall be controlled by both passive and active means.

4.3.1.6 The noise generated by the plant shall be minimised by selecting inherently quietequipment and processes and, where unavoidable, acoustic enclosures.

4.3.1.7 Special note shall be taken for electrical drives that are electronically controlled whichhave an inherent noise generation through the motor drive shaft. This shall be takeninto account with respect to noise abatement. Noise abatement technical informationshall be obtained from the drive manufacturer. Resonance points, if applicable, shall beprovided in the ramp-up to full speed.

4.4 Standardisation

4.4.1 General

The selection of major equipment must not be done in isolation. Equipment already usedwithin AATC must be considered.

When selecting conveyor belting for purposes of an FEL 3 Study or Detail Design,belting already used at AATC operations must be considered.

For SIB type project designs, it is essential to stick to standard equipment and supplierbrands which are already used at the specific Operation unless the deviation can bemotivated.

A preferred vendors list is provided inAppendix A: Preferred Vendor List.Vendors notlisted are not necessarily excluded nor are vendors tabulated in order of preference.


Page 13 of 68


14/68



DOC NO AATC000859

4.5 Belt Conveyors

4.5.1 Conveyor Design Criteria

Conveyor designs are to be in accordance with the latest ISO 5048 Standard,Continuous mechanical handling equipment and guidelines prepared by ConveyorEquipment Manufacturers Association (CEMA).

Conveyors must be designed for continuous operation and starting under full designload.

4.5.2 Standardisation

4.5.2.1 The conveyor designer is to give consideration to economical design while rationalisingmechanical components for optimum spares holding and interchangeability. Theprocess shall be based on component priority selection as follows:

Priority 1 belting

Priority 2 - drives

Priority 3 - pulleys

Priority 4 other

In view of power savings, right-sizing must be traded off against standardisation.

4.5.3 Vertical inclination

4.5.3.1 The maximum permissible angle of inclination shall be dictated by the material, particlesize distribution, type of loading, belt speed etc. of the particular design.

4.5.3.2 The maximum inclination angle shall however not exceed 13.

4.5.3.3 Where material run-back on the conveyor is expected e.g. conveyors exclusivelyhandling screened oversize or spherical type lumps, conveyor inclinations will be keptbelow 10.

4.5.3.4 For stacker boom belts, the inclination angle, and subsequently the angle at whichmaterial is loaded, will be limited to 14.

4.5.3.5 For normal loading conditions, with the tail pulley positioned for full trough, the conveyorincline should be 0.5 to provide effective drainage.

4.5.3.6 The maximum incline at loading shall not exceed 5

4.5.4 Vertical curves

Dynamic calculations must be performed for all vertical curves to ensure safe andreliable conveyor operation. Calculations must be based on the worst case combinationof conveyor loading and geometry.

A suitable factor, taking cognisance of the start-up device, must be applied to the


Page 14 of 68


15/68



DOC NO AATC000859

calculated dynamic start-up tensions when calculating the required concave radius.

4.5.4.1 For concave curves, the following criteria should be met:

On all conveyors featuring trippers (eg. stacker feed conveyors), the belt shall not lift offthe radius during start-up or normal running when loaded to 15 % of the conveyorsmaximum design capacity in the curve only, with the rest of the belt fully loaded for theload-case causing highest tension in the curve. The belt mass used for thesecalculations shall be based on 50 % top cover wear. Belt-lift control must be consideredwhere it is not possible to satisfy these criteria.

For cases where the rear tangent point is close to the feed chute, the above calculationshall be repeated with load up to the rear tangent point and no load on the belt in thecurved section to ensure that the belt will never lift into the chute or skirt sections.

On all other conveyors, the belt shall not lift off the radius during start-up or normalrunning when empty. The belt mass used for these calculations shall be based on 50 %top cover wear.

Centre tension in the curve area shall be limited to 115 % of the maximum rated tensionfor the particular conveyor.

The edges of the belt shall not buckle in the curve area.

4.5.4.2 For convex curves, the following criteria should be met:

The additional stress imposed on the idlers as a result of the convex curve shall notlead to idler shaft deflections and idler bearing lives that do not comply with Anglospecifications.Edge tension in the curve area shall be limited to 115 % of the maximum rated tensionfor the particular belt.The centre of the belt shall not buckle in the curve area.

4.5.5 Horizontal curves overland conveyors

Belt wander must be considered for all conditions of loading as well as for all weatherconditions and must be limited to approximately 100 mm as a guideline.

It is recommended to use stringer widths for the next belt size up within horizontalcurves. Throughing idlers will then be for the selected belt width while return idlers willbe for the next size up.

The layouts for horizontal curves must be based on a minimum radius of 4 km. Whereroute requirements and existing infrastructure dictates otherwise, a smaller radius maybe allowed on concession provided that the design can be justified.

4.5.6 Conveyor Dynamics


Page 15 of 68


16/68



DOC NO AATC000859

4.5.6.1 All conveyors shall be analysed for behaviour during starting (for vertical curves),coasting and where applicable, braking.

4.5.6.2 For conveyors >1 km, or where special profiles are encountered, dynamic transientsand the application of torque prior to starting must be considered.

4.5.7 Conveyor Capacities, Widths and Loading

4.5.7.1 Conveyor design capacities shall be calculated from the Life of Mine plan and recordedon a flow sheet. Only the approved flow sheet capacities shall be used for detailconveyor designs.

4.5.7.2 The width of belt shall be selected as follows:

For a maximum lump size up to 180 mm:Flow sheet peak capacity and the standardrecommended edge distance shall be used according to the latest ISO 5048 Standard,Continuous mechanical handling equipment and CEMA.

The designer shall optimise belt speed and installed power by achieving as close aspossible a belt loading of 80 % full at the installed power. Where designs incorporatetrippers and multiple feed points, the belt loading must be reduced.

For maximum lump size over 180 mm:As a minimum requirement, the belt width shallbe maximum lump size x 4 and then selecting the closest standard belt width above thisvalue. Thereafter, the criteria above for a maximum lump size below 180 mm shallapply.

4.5.8 Feed factors

4.5.8.1 In order to cater for fluctuations in feed to the conveyors, the following feed factors shallbe used as a guideline:

Appl ication Feed factor

Belt and apron feeders where steadystream controlled feed is expected.

1.1

Vibrating, table feeders etc. where surgesand significant short term flooding mayoccur on the receiving conveyor belt

1.15 - 1.25

(depending on the feeder type)

Reciprocating feeders 1.7

Where there is no feed control e.g.Langlaagte chutes under hoppers / boxfronts.

2.0

* The above factors will be incorporated in the conveyor designs but will not be reflected inthe flow sheet capacity.Table 3 Feed Factors


Page 16 of 68


17/68



DOC NO AATC000859

4.5.9 Conveyor belt speeds

4.5.9.1 The general philosophy of wide and slow belts shall be adopted with the following

recommended speeds:

Incline conveyors < 4 m/s

Plant surface transfer conveyors 2 to 3 m/s

Overland conveyors < 4.5 m/s

4.5.9.2 For typical transfer heights in the chutes, a nominal 250 mm lump will produce up to900 Joules on impact with the receiving belt, which is the upper limit of the allowableimpact energy. It therefore follows that the initial kinetic energy of the lumps entering the

transfer chutes be minimised by way of conservatively slow belt speeds.

4.5.9.3 Where multiple feed points are required, lower speeds must be considered to reducespillage.

4.5.10 Conveyor artificial friction factor f

4.5.10.1 The guideline design values for the coefficient of friction f for idler resistance and flexureof the material and the belts, are as follows:

Overland conveyors :fc = .019 fr = .017

Curved overland conveyors :fc = .0195 fr = .018

In-plant conveyors :fc = .02 fr = .022

In-plant ROM conveyors :fc = .022 fr = .022

4.5.10.2 A friction factor of 0.022 should be used for both underground and surface conveyorswith an adjusted length factor Lo of 60m for all conveyors longer than 100 m.

4.5.10.3 In extremely cold conditions during winter mornings a load factor of between 1.1 and1.2 should be applied when selecting the sizes of the drives.

4.5.10.4 The above factors serve only for static analysis. Visco-elastic friction, indentationresistance and idler resistance calculations shall be included in the design of longoverland conveyors.

4.5.11 Conveyor Drive Systems

4.5.11.1 The design, selection and layout of the drive systems for conveyors shall be determined


Page 17 of 68


18/68



DOC NO AATC000859

by the power, tension and wrap requirements.

4.5.11.2 The absorbed power at the drive pulley is calculated in accordance with the latest ISO

5048 standard, Continuous mechanical handling equipment, using the artificial friction

factors f being selected from section4.5.10.

4.5.11.3 The absorbed power at the motor is that calculated at the pulley shaft, divided by the

combined gearbox and fluid coupling efficiency, approximately 0.94, depending on

selection, where fitted above 22 kW.

4.5.11.4 For VSD units, the efficiency is taken as 0.97, unless otherwise certified by the OEM.

4.5.11.5 The absorbed power at the motor is then multiplied by a factor of 1.1 for conveyors with

single drives. Thereafter, the next most suitable motor size up is selected in each case

as well as considering standardisation. For multiple drives, load sharing must beconsidered. Although a factor of not less than 1.1 is to be applied, specific consideration

is required to ensure that large drives are not oversized.

4.5.11.6 The drives for incline, surface transfer and main overland conveyors shall be sized for

the full length of conveyor as per the conveyor route profiles and design capacity.

4.5.11.7 Single head drive configurations may be considered for large conveyor drives (> 250kW) where the head is elevated one floor level only. Special consideration must betaken to ensure that proper maintenance can be done on scrapers and that facilities areavailable for the change out of pulleys, motors and reducer. A trade-off must be doneagainst a ground level installation.

4.5.11.8 Where drive sizes are 250 kW and smaller, elevated drive installations (in excess of asingle floor) may be considered provided that provision is made to remove the drive anddrive pulley to a conveniently located platform which can be accessed via mobilecranes.

4.5.11.9 Head pulley drives up to 90 kW is permitted on cantilevered conveyors, such as overstockpiles.

4.5.11.10 If the drive is at the head end of the conveyor, the head/drive pulley shaft shouldbe extended so that a clearance of approximately 500 mm is obtained between drive

and conveyor steelwork.

4.5.11.11 Right-angled, bevel helical gearbox units are to be used in a torque armconfiguration. The output shaft of the gearbox will be fitted with a rigid Bikon-typecoupling for mounting onto the drive pulley coupling.

4.5.11.12 The drive station layout shall be such that torque arms are always undercompression.

4.5.11.13 The drive station layout shall be such that the belt is always driven on the cleanside.

4.5.11.14 The selection guideline table for drive preference on various conveyorapplications is shown below.


Page 18 of 68


19/68



DOC NO AATC000859

Type conveyor VSDFluid

CouplingElectronicSoft Start

Remark

U/G Section No 1st No Dusty, Low tech

U/G Trunk 1500 m 1st 2nd No Variable Speed (load)

Shaft > 50 m lift 1st 2nd No Start-up and inspection

Overland > 2 km 1st 2nd No Start-up and inspection

Plant < 2 km 2nd 1st No F cplg Start time OK

Plant Single drive No 1st No

Plant < 110 kW No 1st 2nd ESS more cost effective

No Not permitted, 1st Preferred choice, 2nd Alternative option

Table 4 Drive preference for various conveyors

4.5.12 Couplings

4.5.12.1 Fluid couplings will be fitted on the high speed side of all drives exceeding 22 kW whereVSD or Electronic starters are not provided.

4.5.12.2 All couplings shall be complete with guards.

4.5.12.3 All low speed couplings shall be of the rigid flange type, accurately aligned and fitted toshafts via locking elements (no keyways allowed on shafts). The drive supplier shall fitthe rigid couplings to the pulley at the pulley suppliers premises.

4.5.12.4 Drives with an installed power exceeding 22 kW shall be fitted with a soft starter i.e.fluid coupling or electronic.

4.5.12.5 For long overland conveyors with high inertia where the start-up times would be inexcess of 50 seconds (which is the limit of the capability of fluid couplings), VariableSpeed Drives (electrical VSDs) are selected.

4.5.12.6 The overhung on motor output shafts must be checked when using large fluid couplingsizes. Jack shafts may be required to support the fluid coupling.

4.5.13 Belting

4.5.13.1 Steel cord conveyor belting shall comply with the latest AA Specifications, Steel cordreinforced conveyor belting (AA_SPEC_377022) and Steel cord reinforced conveyorbelting (SANS 1366).

4.5.13.2 All fabric conveyor belting shall comply with the latest SANS Specification, Generalpurpose textile reinforced conveyor belting (SANS 1173).


Page 19 of 68


20/68



DOC NO AATC000859

4.5.13.3 PVC impregnated solid woven conveyor belting shall comply with the latest SANSSpecification, Fire retardant textile reinforced conveyor belting (Solid woven PVC,SANS 948 and SANS 971).

4.5.13.4 All conveyor belting shall be selected with consideration of the standardised list ofbelting already in use at Anglo Coal plants.

4.5.13.5 Ply belting to be natural rubber, minimum 3 ply with suitable top and bottom covers,minimum 3 mm and 2 mm respectively. The top to bottom cover ratio is not to exceed3:1.

4.5.13.6 Conveyor belt final selection shall be based on the calculated tension takingstandardisation into consideration.

4.5.13.7 In determining the length required allowance shall be made for hot vulcanized splicing.

4.5.13.8 Mechanical clips may be used in emergency situations only.

4.5.13.9 During belt and cover selection, consideration must be given to minimise the risk ofigniting flammable gas during installation and operation. Belt selection must also bedone considering the possibility of burning coal to minimise the risk of fire and noxiousgasses.

4.5.13.10 In selecting the belt type, the following table must be used as a guideline:

Area applicat ion Bel t type

Tip, raw coal

Ply belts where impact permits.

Solid woven to be considered on tip clearance

belts and where significant steel contamination

is anticipated.

Sacrificial belts and applications where high

abrasion is expected are generally equipped

with ply belts.

Evaluate the possibility of burning coal /

spontaneous combustion.

Plant Ply belts

Stock yards Ply belts

Interconnecting

overland conveyors

shorter than 1 km

Ply belt

Solid woven where justified, avoid steel cord.

Overland conveyors Tensions normally require steel cord but

consider solid woven where possible.

Shaft & high lift

conveyors

Tensions normally require steel cord but

consider solid woven where possible.Table 5 Belt t ype selection


Page 20 of 68


21/68



DOC NO AATC000859

4.5.14 Belt service factors

4.5.14.1 The following minimum service factors shall be applied to all conveyors based on thenormal steady state tensions:

Solid woven belting : 10

Fabric ply belting : 10

Steel cord belting : 6.67

4.5.15 Belt Jointing

4.5.15.1 Conveyor belts will be joined in accordance with the latest Anglo AmericanSpecifications (Cold splicing of plied (textile) conveyor, AA_SPEC_377010), (Splicing

of solid woven conveyor belting, PVC & PVG(Nitrile), AA_SPEC_377088) and (Splicingof steel cord reinforced conveyor, AA_SPEC_377033) whichever is applicable to theselected conveyor belting.

4.5.15.2 The conveyor belt splicing shall be done in consultation with the conveyor beltmanufacturer.

4.5.16 Belt installation Winch/Splice station/Replacement and maintenance of belting

4.5.16.1 Provision shall be made to provide easy access for replacement and repair of belting. Abelt replacement study is to be conducted.

4.5.16.2 A belt reel holder will be installed at the head end or tail end of every conveyor belt onsurface. In cases where the reel cannot be accommodated at the head or tail, provisionwill be made at the take-up section.

4.5.16.3 A belt maintenance station shall be provided such that:

The belting to be replaced may be easily pulled off the conveyor.

The replacement belting may be easily pulled onto the conveyor without the riskof damaging the belting.

Splices may be easily and accurately made.

4.5.16.4 The splicing area is protected from the elements.

4.5.16.5 Provision will be made to install suitable winches to facilitate the initial and anysubsequent pulling-in of a new belt. These will be located to pull the belt up from the tailend as well as to pull the return side down from the head end.

4.5.16.6 Sheaves may be permanently mounted but the winches will be installed on preparedmounts and connected as required.

4.5.16.7 The belt maintenance station for overland conveyors shall be provided with outdoor

industrial power outlets for 220 volts (2x) and 550 volts (1x) and water. The floor of the


Page 21 of 68


22/68



DOC NO AATC000859

belt maintenance station shall be concrete and shall be bunded.

4.5.16.8 Belt clamps shall comply with the CMA specification MC-01.

4.5.17 Holdbacks

4.5.17.1 A full risk assessment per conveyor belt shall be carried out prior to selection of theholdback considering:

Material loading combinations on conveyor.

Drive loading conditions during startup, abort start, normal running and jammedtake-up or belt.

Abnormal conditions such as wash down.

Stored energy. Repair of conveyor components with a fully loaded incline.

Maintenance belt clamp of 60 kN capacity.

Assistance from anti-runback idlers.

Load release.

4.5.17.2 Where the design dictates the need for a holdback, external or reducer integrated unitsmay be considered.

4.5.17.3 Slow speed backstops, mounted directly onto the drive pulley shaft or the intermediatereducer shaft, are preferred.

4.5.17.4 High speed holdbacks, fitted between the motor and the reducer, may be considered forconveyors equipped with single drives.

4.5.17.5 Where it is desired to have a high speed holdback installation on a multiple drive

configuration, torque limiting type devices are required to ensure load sharing.

4.5.17.6 For external holdbacks, a horizontal mounting configuration will reduce bearing loading

and is therefore preferred.

4.5.17.7 Although stiff support steel is required to transfer the holdback reaction forces, the

torque arm end of an external unit must not be rigidly attached. This will preventdamage to the bearings of the device.

4.5.17.8 The mounting of the torque arm must not permit any slack between the device and the

support steel. Cushioning between load contact surfaces is precluded.

4.5.17.9 Holdback selection must be based on the calculated runback load of the belt in

conjunction with a dynamic impact factor. The holdback rating shall not be less than the

maximum torque capacity of the gearbox.

4.5.17.10 Where required, turn down of the shafts may be considered to accommodate

maximum bore for selected backstop, provided that permissible shaft stresses, as


Page 22 of 68


23/68



DOC NO AATC000859

provided in AA_SPEC_371001, are not exceeded.

4.5.17.11 For standardization purposes, the selection of the internal holdbacks shall bebased on the highest torque requirement across the range of affected conveyors.Standardised reducer units must be interchangeable, hence internal holdbacks must befitted for all these units unless economical considerations dictates otherwise in whichcase clear visual identification must be provided.

4.5.18 Anti-runback idlers

4.5.18.1 Anti-runback idlers shall be installed to satisfy the requirements of the DMR.

4.5.18.2 Anti-runback idlers are generally not required on conveyor belts which have a lift of less

than 7 m. Special cases may however occur. Calculations and a risk assessment aretherefore still required.

4.5.18.3 In designing new steep incline conveyors, consideration must be given to increase thecarry idler spacing to enhance the friction breaking force should a belt failure occur.

4.5.18.4 In determining the number of anti-runback idlers required, a conservative friction factorof no more than 0.3 must be used. This value caters for wet belts, condensationassociated with temperature change and build up of coal dust on contact surfaces.

4.5.18.5 The following design parameters must be considered when selecting anti-runbackidlers:

3-roll idler sets are preferred The installation pattern, which formed the basis of the design calculations, must

be adhered to.

Clear marking is required.

Emergency conditions such as the jamming of the tail pulley or feed chuteblockage must be considered.

Where conveyors are equipped with 5 roll idler sets, the wing rolls should neverbe fitted with anti-runback idlers since the contribution to braking friction isnegligible

4.5.18.6 Anti-runback idlers can never be installed in place of a positive holdback.

4.5.19 Pulleys and shafts

4.5.19.1 Pulleys and shafts shall be strictly in accordance with the latest AA Specification,conveyor pulleys and shafts, AA_SPEC_371001 and SANS Specification, conveyor beltpulleys, SANS1669.

4.5.19.2 Drive pulleys will be lagged using 6 mm thick smooth ceramic tiles epoxy bonded usinga high bond epoxy, directly to the pulley shell. Rubber lagging is acceptable for non-drive pulleys.

4.5.19.3 No conveyor pulleys shall be crowned. However, where reversible belts have beenapproved by concession, crowning may be required.


Page 23 of 68


24/68



DOC NO AATC000859

4.5.19.4 The lagging philosophy of the operation shall be considered when conducting SIBdesigns and projects.

4.5.19.5 Plummerblocks should be the split type.

4.5.19.6 Spherical roller bearings with an adapter sleeve should be used.

4.5.19.7 Plummer blocks with its bearings to be fitted with an easily accessible grease nipple.Inaccessible grease point must be equipped with a hydraulic hose and grease block tofacilitate safe remote manual lubrication.

4.5.19.13 Plummer block orientation shall be such that the bearing force acts through thebase of the plummer block. Cap bolts shall never be under tension.

4.5.19.14 Bearing temperatures on critical belts will be monitored at the head, tail, drive and

take-up pulleys using resistance temperature detector. (RTD)

4.5.19.15 All pulley approach points will be fitted with nip protection.

4.5.19.16 The number of pulleys must be kept to a minimum when designing newconveyors.

4.5.20 Idlers

4.5.20.1 Idlers shall be in accordance with the latest AA Specification, belt conveyor idlers androlls (AA_SPEC_373001) and shall bear the SANS certification mark to the latest SANSSpecification, conveyor belt idlers.

4.5.20.2 Idler spacing selection must be done by balancing the capital expenditure withoperational costs.

4.5.20.3 The maximum allowable idler shaft deflection is limited to 8 minutes at the designedthroughputs.

4.5.20.4 For the average operating throughputs, the minimum idler life is 40 000 hours.

4.5.21 Troughing idlers

4.5.21.1 All troughing idlers shall comply with the latest Anglo American specification, Beltconveyor idlers and rolls (AA_SPEC_373001).

4.5.21.2 Carry idlers shall be specified individually for each conveyor, based on the material,particle size distribution, etc.

4.5.21.3 Carry idlers shall be designed based on the peak capacity.

4.5.21.4 The 3 roll idler configurations are preferred. 5 roll idler configurations may beconsidered for belt widths exceeding 1200 mm.


Page 24 of 68


25/68



DOC NO AATC000859

4.5.21.5 The preferred troughing angle is 35 although 45 and higher may also be used whenjustified.

4.5.21.6 The head frame or the stringers leading up to the head frame shall include a transitionsection to flatten the belt in accordance with the CEMA recommendations, precautionsshall be taken to prevent spillage at this point.

4.5.21.7 Head and tail transitions are to be designed to run out to 0 by installing the appropriatetransition idlers. 3 idler sets are generally required.

4.5.21.8 When required, the tail pulley may be positioned at half or third trough to reduce thetransition distance. This is however not preferred.

4.5.21.9 Standardization across designs remains to be an important consideration.

4.5.21.10 High angle troughing idlers should be considered to eliminate long and highmaintenance skirting on conveyors with multiple loading points typical for coal plantproduct and discard belts.

4.5.22 Impact idlers

4.5.22.1 Impact resulting from the transfer of material shall be absorbed by impact idlers.

4.5.22.2 Standard steel rolls can however be used on -20 mm material. Idlers located in impactareas are generally series 30 or 35 with 152 mm diameter.

4.5.22.3 Impact idlers shall be 45 trough, 159 mm rubber disk rolls to be used for coarsematerial.

4.5.22.4 Where impact is abnormally high, a torsion rubber mounting system is to be consideredin conjunction with rubber disk idlers. The rubber torsion mounting arrangement is to beapproved by the Engineer.

4.5.22.5 Idlers located within the skirted area at loading points will be mounted on quick releasemountings which will allow the complete idler frame to be lowered for idler rollreplacement.

4.5.22.6 Solid SKEGA beds should not be used.

4.5.23 Return idlers

4.5.23.1 Return idlers shall be specified individually for each conveyor, based on length, beltwidth, tracking difficulties, etc.

4.5.23.2 All conveyors 1200 mm wide and above should be 10 vee, 2 roll return idlers, subjectto belt troughability and the specific detail design.

4.5.23.3 As a guideline, conveyors below 1200 mm wide should be fitted with single roll flat


Page 25 of 68


26/68



DOC NO AATC000859

return idlers unless troughability calculations prove otherwise.

4.5.24 Take-up units

4.5.24.1 All conveyors with horizontal pulley centres 30 metres and longer will be provided withgravity take-ups, either vertical or horizontal to suit the design.

4.5.24.2 For short conveyors (less than 30 m) mechanical screw take-ups may be used.

4.5.24.3 All take-ups shall be designed to accommodate the elastic and permanent stretch of thebelt, calculated from the belt modulus as specified by the belting Supplier.

4.5.24.4 In addition to belt stretch, the take-up must make provision for belt storage such thatfive splices in case of overland conveyors and three splices in the case of shorter plantconveyors is catered for.

4.5.24.5 Allowance shall also be made for sufficient movement for splicing, and whereapplicable, for rope tie offs on horizontal take-up trolleys.

4.5.24.6 On vertical gravity take-ups, deflector plates, with adjustable rubber scrapers, arerequired to prevent ingress of spilled material between the belt and the take-up pulley.

4.5.24.7 The take-up shall include the counterweight or winch, sheaves, steel wire rope,attachments, etc. to maintain the required belt tension under all operation conditions.

4.5.24.8 The take-up trolley longitudinal wheel centres will have a ratio of

:1 in relation to thewidth of the trolley as a minimum. This aspect ratio shall apply to vertical gravity take-upcarriages as well.

4.5.24.9 The take-up trolley must have locating wheels on one side and floating wheels on theopposite side of the carriage.

4.5.24.10 Provision shall be made for the take-up trolley to be locked in position, and thetwo belt strands entering and exiting the horizontal take-up to be clamped duringmaintenance activities.

4.5.24.11 A manually operated electric winch with local starting controls shall be provided

on all horizontal take-up towers to facilitate raising and lowering of the counterweightbox under controlled conditions.

4.5.24.12 Vertical take-up counter weight shall be provided with suitable guide channels toensure positive location of the counterweight in the guides.

4.5.24.13 The desired counterweight mass should be made up with plate packs in a supportcradle. Consideration may be given to properly drained counterweight boxes in order tofacilitate the use of steel punchings or similar material, given the high cost of steelplates.

4.5.24.14 Steelwork, walkways, stairs platforms, etc. to afford safe and adequate

operational and maintenance access shall be provided.


Page 26 of 68


27/68



DOC NO AATC000859

4.5.24.15 For vertical gravity take-up, over 6m in height, belting flap to be restrained withflat return idler guides. This configuration should however be avoided.

4.5.24.16 Vertical gravity take-up should have a clearance between frame and guides ofapproximately 10 mm per side.

4.5.24.17 Gravity take-up towers shall be of sufficient height to accommodate the change inthe length of the conveyor belting under all operating conditions with a minimum of500mm travel distance before any object will be encountered.

4.5.24.18 Ny-lock (prevailing torque) nuts to be used on take-up frames.

4.5.24.19 Gravity take-up towers shall have a buffer at the bottom. This buffer shall be ableto absorb the impact of the free falling take-up weight to prevent damage to thestructural components. The preference is to use a sand box with screed closure.

4.5.25 Belt scrapers and duff chutes

4.5.25.1 A double bladed secondary belt scraper shall be fitted at all head pulleys. Scrapersshall be adjustable and self-compensating for wear. Sufficient space for servicing is tobe allowed. Belt scrapers must be easily and safely accessible for maintenancepurposes.

4.5.25.2 Primary scrapers are occasionally used at certain applications with success and

therefore not prohibited.

4.5.25.3 All scrapings from the belt cleaner shall be deposited onto the receiving conveyor bymeans of a dribbling chute. The side angles of the duff chute shall be inclined such thata valley angle of not less than 70 degrees is obtained. All the corners shall be roundedsuch as to allow the free flow of duff material to the receiving conveyor. A chute impactangle of less than 20 degrees shall be maintained.

4.5.25.4 Dribble chutes will be lined with UHMW liners with a 6mm thick rubber backing ormanufactured from stainless steel polished on the sliding surfaces.

4.5.25.5 Chutes must ideally be designed such that duff can be removed by the main material

stream.

4.5.26 Belt ploughs

4.5.26.1 V-return ploughs shall be installed on the following positions:

Clean side of the return belt at tail pulleys

Approach to bend pulley on vertical gravity take-ups.

At drive stations prior to the HT snub pulley


Page 27 of 68


28/68



DOC NO AATC000859

4.5.26.2 Care must be taken to position tail scrapers such that material is not scraped into thetail guard area.

4.5.26.3 Where V-return idlers are used, the positioning of the plough must be such that proper

contact between the belt and plough is maintained. Flat return idlers must be provided.

4.5.26.4 Where access to one side of the belt for cleaning purposes is not available, biasploughs shall be installed so that material is scraped off to the side where access isreadily available.

4.5.26.5 Where ploughs are installed on elevated conveyors, safety precautions due to fallingmaterial shall be taken. Easily cleanable catchment boxes should be installed.

4.5.27 Skirting

4.5.27.1 Continuous skirting is to be used for multiple load points onto a single belt. Flared

skirting or spaced skirting shall only be incorporated into the design with the prior

approval of the Engineer.

4.5.27.2 Skirting rubber shall be 40 shore hardness or below. Used conveyor belting in skirt seal

locations is prohibited.

4.5.27.3 AATC standard skirts will be installed at all single loading points.

4.5.27.4 All conveyor feed chutes shall be equipped with steel skirting to contain material at the

feed point. Skirts shall extend a minimum distance of 1 m past the stabilized material on

the belt. Chute skirt covers to be easily removable.

4.5.27.5 All discharges below crushers, centrifuges etc. shall be fully enclosed to eliminate

spillage completely.

4.5.27.6 High angle troughing idlers may be considered to eliminate long and high maintenance

skirting on conveyors with multiple loading points typical for coal plant product and

discard belts.

4.5.28 Safety and guarding

4.5.28.1 All safety guards shall be in accordance with the latest Anglo American Best Practise

Guideline, AA_BPG_375001

4.5.28.2 In addition, guarding shall conform to the requirements of the Minerals Act, the Mines

Health and Safety Act and where these do not cover a particular condition, the

Occupational Health and Safety Act (85/1993) Incorporation of Safety Standards in the

Construction Regulations 2003.

4.5.28.3 Risk assessments, as envisaged by the Mines Health & Safety Act, of all operating and


Page 28 of 68


29/68



DOC NO AATC000859

maintenance procedures shall be undertaken by the Contractor. Personnel nominated

by the Company shall be involved with these risk assessments. The outcomes of these

risk assessments shall be included in the appropriate operating or maintenance

manuals.

4.5.28.4 Shaft mounted power packs must be equipped with safety chains in view of a past fatal

accident. A standard AATC design concept is available on request.

4.5.29 Guarding design and mounting

4.5.29.1 In areas where maintenance access is required, guarding must be designed to swivelalong the vertical plane on bullet type hinges. The opposite end must be fixed with bolts

so that physical work must be done to gain access. This type of guards can typically be

used within horizontal take-up areas of conveyors. The swivel door must be removable

by two persons.

4.5.29.2 The above requirement does not apply when the removal of guarding is not required for

maintenance and change-out of equipment, belt replacements etc. This type of

guarding is considered to be fixed.

4.5.29.3 Fixed panels shall be mounted using M16 hot dip galvanised fixing bolts (min 4 bolts

per panel). Bolts and nuts shall be easily accessible for installation of the guard.Suitably designed fixing brackets shall be used.

4.5.29.4 Where swivelling guards are not deemed possible or practical where access is required,

specific care must be taken to ensure that the removal of all panels can be safely done

by one person.

4.5.29.5 Guard lifting handles must not protrude into the walkways.

4.5.29.6 Greasing points must be safely accessible without the removal of guards. Inaccessible

points must be equipped with a hydraulic hose and grease block located at convenient

location.

4.5.29.7 Conveyor under-belt guards must be provided on elevated sections to provide a

working platform to replace return idlers and to prevent large objects e.g. idlers to fall to

the ground but not to cause material build-up. The preferred construction is to have

welded mesh panels, welded into a frame which is bolted into the gantry steelwork.

4.5.29.8 Guards shall be painted to AA_SPEC 164050_Corrosion Protection of steelwork with

coatings and colour coding to AA_SPEC 164051_Plant Colour Coding.

4.5.29.9 Materials of construction and panel mass to comply with the table below:


Page 29 of 68


30/68



DOC NO AATC000859

Guard panel type Frame const ruction Guard mesh Total mass (kg)

Fixed 50x50x6L Flatex type 348 / Eq 50

Swivel 50x50x6L Flatex type 348 / Eq 50

Light weight removable None 100x20x3 Specimesh M389 / Eq* 25

Under-belt 50x50x6L** 100x100x10 welded mesh Not restricted

*Aperture size subject to specific application.

**Span dependent, serviceability may be relaxed on concession.Table 6 Guarding design and mount ing

4.6 Chutes

4.6.1.1 The minimum width of the conveyor feed chutes (measured inside of liners) shall be 2,5x the particle size. The width of such feed chutes shall not exceed 2/3 of the conveyorbelt width.

4.6.1.2 Chutes shall be designed to pass the peak load continuously, without spillage or build-up, and to transfer it to the receiving equipment smoothly and equally distributed acrossthe receiving equipment. The chute shall also pass the maximum lump size withoutblocking, hanging-up or spilling or excessive wear, and shall transfer it to the receivingequipment such that the possibility of damage is minimized.

4.6.1.3 Chute design shall accommodate dust extraction and suppression requirements whereapplicable (on transfers within buildings, chutes carrying dry coal). The velocity of dustshall be kept to a minimum regardless of whether dust extraction or suppression isapplied. Connection flanges shall be supplied for dust suppression or extractionequipment where such systems are required.

4.6.1.4 The impact pressure on the chute and on the receiving equipment shall be kept to aminimum and shall not exceed 8 kPa.

4.6.1.5 The angle of impact, i.e. the angle between the material stream and the impactingsurface, shall be minimised and shall preferably be less than 20.

4.6.1.6 Suitable support for the chute shall be provided. In designing the chutes, the forceslikely to be encountered as a result of large lumps passing through the chute shall betaken into account.

4.6.1.7 Where appropriate, deflector chutes must be provided at ploughs, take-up and drives.

4.6.1.8 When chute plates have to be stiffened, care must be taken in positioning stiffeners sothat no water traps occur.

4.6.1.9 Although chutes need to be suitably stiffened in line with the liner selection, overstiffening must be avoided.

4.6.1.10 New ceramic tiles have a high co-efficient of friction, which must be considered when


Page 30 of 68


31/68



DOC NO AATC000859

conveying fines.

4.6.1.11 Light weight chute inspection doors must be provided with welded hinges. To preventfinger injuries, these doors shall always open sideways, never to the top or bottom.

4.6.1.12 Where possible, the head snub pulley must be located within the main chute so that thefines can be carried away with the main flow of material. The chute back plate must bepositioned such that there will be no build-up of the fine material.

4.6.1.13 The guideline for the required clearance between the belt and chute is obtained by theratio of the selected belt width divided by 12.

4.6.1.14 In order that degradation of material and belt wear may be minimised, all transferchutes shall be designed in accordance with the following principles:

All chute designs shall be based on friction characteristics obtained from bulk solidsflow test for material on material and material on liner surfaces,

In determining chute angles, the co-efficient of friction between the wear material andthe coal shall be taken into account.

The functional design of transfer chute arrangements shall prevail over mechanical andstructural considerations,

Material velocity throughout the entire chute shall be designed in accordance withmeasured friction characteristics for direct sliding and sliding under impact conditions,

Material transferred to chutes shall impinge on the chute at the least practical angle ofimpact,

Where unavoidable and to eliminate impact wear in the top section of the chute, in-linedead boxes will be permitted.

Where a chute transfers material onto a belt conveyor, the difference in the velocities ofthe material in the direction of the conveyor, and the belt shall be within 10% of the beltvelocity for average friction characteristics of the material on the chute liner surface,

The kinetic energy of the largest particle reasonably anticipated on a receiving conveyor

belt shall not exceed 500 joules,

Where the stopping time of a conveyor is such that it may deliver more material to thereceiving equipment than the receiving equipment can absorb without the possibility ofspillage or blockage overloading, provision shall be made for the conveyor head chuteto accommodate the overrun material. The amount of overrun material to beaccommodated shall be based on the peak capacity of the conveyor,

The chute angle at the bottom of the chute shall be minimum 5 steeper than the frictionangle for direct sliding.

4.6.1.15 Transfer point arrangements must be designed to minimise the fragmentation of coal.


Page 31 of 68


32/68



DOC NO AATC000859

4.6.1.16 Blocked chute detection will be installed at all conveyor discharge ends in accordancewith the latest AA Specification, Conveyor belt protection systems (AA_SPEC_673018).

4.6.1.17 Also refer to general plate work and lining requirements under section4.10 Plateworkand Lining.

4.7 Mechanical Design General Requirements

4.7.1 Design

4.7.1.1 All equipment shall be designed:

To be intrinsically safe and easy to operate and maintain,

To facilitate inspection, maintenance, cleaning and repairs,

To ensure satisfactory operation under the conditions prevailing at the site of the works,

To run without undue vibration or excessive noise,

To prevent undue stress being produced by temperature changes.

4.7.2 Design factors

4.7.2.1 Service factor shall be in accordance with the latest AA Specification, MechanicalStandards (AA_SPEC_999022).

4.7.2.2 Where specific manufacturer or other requirements exist, these will be stated in the

relevant equipment specification.

4.7.3 Transmissions

4.7.3.1 Chain drives (Not preferred)

4.7.3.2 Chain drives shall be in accordance with the latest AA Specification, MechanicalStandards (AA_SPEC_999022).

4.7.3.3 Chain drives shall not be specified unless application is essential to the satisfactory

operation of the equipment.

4.7.3.4 V-Belt Drives (Not preferred)

4.7.3.5 V-belt drives shall be in accordance with the latest AA Specification, MechanicalStandards (AA_SPEC_999022).

4.7.3.6 Gearing

4.7.3.7 Gearing shall be in accordance with the latest AA Specification, Mechanical Standards(AA_SPEC_999022).

4.7.3.8 Speed reduction units shall be in accordance with the latest AA Specification,


Page 32 of 68


33/68



DOC NO AATC000859

Mechanical Standards (AA_SPEC_999022).

4.7.4 Bearings

4.7.4.1 Bearings shall be in accordance with the latest AA Specification, Mechanical Standards(AA_SPEC_999022).

4.7.4.2 All bearings must be SKF with the exception for conveyors pulleys (only) where FAGmay be used as an alternative where SKF bearings are not available.

4.7.4.3 The L10 life shall be calculated at the maximum speed and radial and axial loadsresulting from rated motor power.

Mechanical Equipment Minimum L10 Life (hours)

Cranes, trolley and hoists(maintenance)

3,000(Service Class below H3 only)

Gear drives combination drives 60,000

Pumps 60,000

Agitators 80,000

Conveyor pulley plummer blocks 100,000

Conveyor idlers 40,000

Screens 80,000

Compressors, blowers, process 100,000

Table 7 Minimum L -10 Bearing lif e

4.7.4.4 Plummer blocks shall be designed and installed such that the belt load acts through themounting base. Stored energy within the conveyor belt must not result in an unsafecondition when the bearing cap is removed.

4.7.4.5 Greasing points shall be provided for all plummer blocks.

4.7.4.6 All electric motors used on VSD installation above 90 kW, must be equipped withinsulated bearings at either the drive or non drive end to mitigate the effect of straycurrents.

4.7.4.7 Bearing sole plates must be supplied loose for site welding to ensure that bearinghousings can be aligned. Galvanising must be grinded off locally prior to site weldingand repaired according to CPS41 A after installation.


Page 33 of 68


34/68



DOC NO AATC000859

4.7.5 Brakes

4.7.5.1 Brakes are generally not required on conventional conveyors.

4.7.5.2 Brakes shall be in accordance with the latest AA Specification, Mechanical Standards(AA_SPEC_999022).

4.7.5.3 Where required, brakes shall be fitted to the high-speed input shaft of the speedreducers and on the reducer side of the coupling, fail safe, with automatic wearcompensation, and adjustable brake torque.

4.7.5.4 Disc callipers shall be mounted on rigid supports attached to the same base frame asthe drive.

4.7.5.5 Brake pivots shall be provided with self-lubricating bushings and hardened alloy steelpins on all pivoting joints.

4.7.5.6 Brake rated torques shall be at least 150 % of specified braking torque.

4.7.5.7 Brakes used on out-of-balance loads shall be capable of arresting the load in the eventof a trip of the motor in the maximum out-of-balance condition.

4.7.5.8 The rated heat dissipation shall allow for the specified stops per hour without fade orloss in holding.

4.7.5.9 Brakes shall use asbestos-free shoes and pads.

4.7.6 Lubrication

4.7.6.1 Lubricants and lubrication shall be in accordance with the latest AA Specification,Mechanical Standards (AA_SPEC_999022).

4.7.6.2 All equipment which normally contains lubricant and is despatched without suchlubricant shall have their interior sprayed with a suitable moisture inhibitor, to preventcorrosion during transport and storage. Such equipment shall carry clear legible taggingindicating that it does not contain lubricant. All machinery and equipment shall bechecked for cleanliness and lubrication prior to testing or start-up.

4.7.6.3 As far as possible a centralised lubrication system shall be considered for multiple itemsof equipment supplied. Where a centralised lubrication system is not justified, multiplelubrication points in close proximity shall be plumbed to a central manifold blockaccessible without removing safe guards. Lubrication plumbing shall be neatly run andsupported as required. Lubrication points shall be labelled to indicate the point supplied.

4.7.6.4 All oil lubricated equipment shall be provided with a valve at the outlet (where practical)so that samples for oil analysis may be easily taken.

4.7.6.5 First fill of lubricants shall be agreed by project team and included in the Capex or SIBcosts.


Page 34 of 68


35/68



DOC NO AATC000859

4.7.7 In-plant Maintenance Facilities

4.7.7.1 In designing or selecting the equipment, attention shall be given to the ease ofoperation and maintainability of the plant as well as operational costs.

4.7.7.2 The design and selection of equipment shall be directed towards minimizingmaintenance and maintenance durations.

4.7.7.3 Steelwork, walkways, stairs, platforms, etc. must allow safe and adequate operationaland maintenance access shall be provided.

4.7.7.4 Crawl beams, equipped with crawls but not lifting tackle, strategically placed so that allheavy lifts required to maintain the plant and equipment may be safely and easilycarried out shall be provided.

4.7.7.5 Equipment must be arranged so that overhead crawl or lifting beams provide simple

and adequate suspension for in situ stripping and/or removal to an external workshop.

4.7.7.6 Electrical overhead travelling cranes will be provided in the main plant and plantworkshop. Cranes shall be in accordance with the latest BS 466 standard.

4.7.7.7 The plant crane will be sized to lift the heaviest piece of equipment within the cranesreach.

4.7.7.8 Crawl beams will be fitted over equipment that is not accessible by the overhead craneincluding all transfer towers, bins and the discard silo.

4.7.7.9 Crawl beams will be fitted with manual trolleys.

4.7.7.10 Stop blocks will be fitted to both ends of the crawl beams.

4.7.7.11 The safe working load, SWL, must be stencilled onto both sides of crawl beam webafter passing load test certification.

4.7.7.12 No lifts, including construction activities, shall take place on a new crawl beam prior topassing load test certification.

4.7.8 Cleaning operations

4.7.8.1 All floors in wet areas should be concrete and easily accessible for skid steer loaders(bobcat) without obstacles.

4.7.8.2 Skid steer loaders (bobcat) access is required around conveyor tail end areas andinside tunnels.

4.7.9 Dust suppression and extraction

4.7.9.1 All materials handling facilities will be designed to minimise, and where possible, toprevent the generation and liberation of dust.


Page 35 of 68


36/68



DOC NO AATC000859

4.7.9.2 Methodologies will vary from passive e.g. tip dust hood and active systems e.g. waterspray systems.

4.7.9.3 Ducted dust extraction systems and filters are not preferred. These may be used inlimited quantities where required by an analysis of an experienced dust controlspecialist.

4.7.9.4 Water sprays will be used to suppress dust escaping from enclosures. Each waterspray system will be designed for the optimised droplet size and velocity. The objectivewill be to balance the system requirements in terms of water consumption,maintainability, dust suppression efficiency, water quality requirements and simplicity.

4.7.9.5 Where fine droplet sizes are preferred, the spray systems will make use of suitableatomizing nozzles (using either by pneumatic or high pressure hydraulicmethodologies). Water supply systems to atomising dust spray systems will include fine

filtration and possibly reverse-osmosis treatment, as required by an analysis of thequality of the water supply system.

4.7.9.6 Water sprays, where used will be specified in a manner which avoids caking and build-up on materials handling equipment. Sprays must ideally be directed towards theconveyed material.

4.8 Fire protection

4.8.1.1 Fire suppression and detection to be provided in accordance with the latestSpecifications:

AATC000168 Fire protection for buildings and structures

AATC000169 Fire protection for conveyors and coal transfer

4.8.1.2 Risk assessments will be required to finalise the project scope.

4.9 Pipework and Valves

4.9.1 General

4.9.1.1 Piping covered in this document specifically addresses plant related environments. Bulksupply and services to the plant are covered by civil engineering.

4.9.1.2 All piping systems, equipment and design shall comply with the latest relevantstandards, regulations, codes and statutory requirements. (Refer to ReferenceDocuments)

4.9.1.3 Piping systems shall be designed to facilitate reliable and continuous operation, as wellas easy accessibility for operation, maintenance, equipment replacement, handling,

cleaning and inspection.


Page 36 of 68


37/68



DOC NO AATC000859

4.9.1.4 All pipe work, equipment and apparatus supplied and installed shall be designed toensure satisfactory operation under the atmospheric, ambient and other conditionsprevailing at the plant/site.

4.9.1.5 The Contractor shall ensure that all piping and components stored on site are placed onsleepers or pallets. All open ends of piping, valves and fittings shall be provided withplastic or wooden end caps to prevent ingress of dirt and other foreign matter.

4.9.2 Piping Categories

4.9.2.1 Piping is classified under the following categories:

General Purpose

Slurries &

moderately acidicfluids

Alternate of

aggressiveslurries

Fluids

Raw water, potablewater, plant air,instrument air, air forthe filter plant,flocculent, coagulant.

Clarified water,dilute medium,magnetite solutions,polluted water,effluents, correctmedium

Correct mediumdistribution

SpecialCategory

Spray bars inabrasiveenvironments, glandseal water (GSW)

Pump suctions andother high wearitems

Table 8 Piping Categories

4.9.3 Design of Piping Systems

In designing a piping system the following design parameters shall apply:

4.9.3.1 All pipe and fittings supplied shall be new and unused.

4.9.3.2 Pipe routes shall be as short and straight as possible using 45 and 90 bends.

4.9.3.3 Consideration shall be given to the overall piping system behaviour under dynamicconditions. 90 bends do not lend itself to being self-draining; 85 are preferred.

4.9.3.4 Relevant pipe routes shall be self-draining. Drain valves shall be fitted on any pipelineswhich do not self drain, however this should be avoided. No dead legs areacceptable.

4.9.3.5 Pipe deliveries into sumps and tanks shall be directed away from the suction inlet toavoid air entrainment, instrumentation and towar