u u ! I; ~ 1; F1490 BCHPA - Hat Creek Materials Handling; Screening & Crushing Scheme TABLE OF CONTENTS INTRODUCTION SECTION 1

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2 ,~..,.~.~_~,,.,.,,... _~.. ~.,.i,,._ Ii ~ - F490 BCHPA - Hat Creek Materials Handling; Screening & Crshing Scheme TABLE OF CONTENTS SECTION INTRODUCTION Backgrond ::: Scope of Report.3 Acknowledgements ii ~ ;! I; cj SECTION 2 SECTION 3 SUMMARY DESIGN REQUIREMENTS OF MATERIALS HANDLING, SCREENING AND CRUSHING SYSTEMS 3. Introdction 3.2 Rn-of-mine Materials Clay Normal Coal Low Grade Waste Waste for Constrction Petrified Wood in Normal Coal High Clay Content Normal Coal High Grade Coal Coal 3.3 Mine,,., Conveyor Systems 3.3. Normal Coal Conveyor Waste and Clay Conveyor Low Grade Coal/Spare Conveyor 3.4 Primary Crshing Stations 3.4. Dmp Pockets Rn-of-mine Feeders Rn-of-mine Screens Rn-of-mine Breakers Bradford Breakers Krpp Siebra Crsher Wing Crsher Impactors Impactors with Moving Breaker Plates Clay Feeder/Shredders General Design

3 F490 BCHPA - Hat Greek Materials Handlinq, Screening & Crshing Scheme ii TABLE OF CONTENTS SECTION 3 DESIGN REQUIREMENTS OF MATERIALS HANDLING, SCREENING.. AND CRUSHING SYSTEMS- cont. 3.5 Coal Screening and Secondary Crshing 3.5. Introdction Coal Screening ' Conventional Screens Heated Deck Screens Rod Deck Screens Probability Screens Disc Screens Crshing SECTION 4 BENEFICIATION OF LOW GRADE COAL BY WET PROCESSING i:: Introdction Beneficiation by Desliming 4.3 Beneficiation by, Washing 4.3. Plant Reqirements for Washing Projected Washing Reslts SECTION 5 BENEFICIATION OF LOW GRADE COAL BY DRY SCREENING Introdction z-i Theoretical Beneficiation 5:3 Predicted Beneficiation 5.4 Plant Reqirements SECTION 6 DESIGN AND COST OF SCHEME Basis of Design Description of Selected Scheme 6.2. Normal Coal Low Grade Coal Waste/Clay Special Operating Featres CostSmmary Scheme Drawings

4 F490 BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme... TABLE OF CONTENTS SECTION 7 DESIGN AND COST OF TRUCK DUMP AND IN-PIT CRUSHING UNITS 7. Basis of Design 7.2 Description of'selected Scheme 7.3 Cost Smmary SECTION 8 CONCLUSIONS AND RECOMMENDATIONS 8. Conclsions 8.2 Reconnendations for Ftre Testwork 8.3 Recommended Design Featres APPENDIX I APPENDIX II APPENDIX III APPENDIX IV APPENDIX V APPENDIX VI APPENDIX VII Beneficiation by.wet Screening Correlation of Washability Data Correlation of Dry Screening Data Given Data Estimate Smmary Bibliography Drawings

5 c 0 F490 BCHPA - Hat Creek Materials Handling; Screening & Crshing Scheme l-l c ( tl U U : 0 0 ill ( ~ I Ii ;. BACKGROUND SECTION INTRODUCTION The preliminary engineering mining Feasibility Stdy for the No. Deposit at Hat Creek was completed in October 978. Simon-Carves of Canada Ltd. had ndertaken the coal beneficiation section of this stdy. On consideration'of the cost benefits, B.C. Hydro and Power Athority conclded that beneficiation shold not be inclded in the Mining Scheme, and that the Power Plant shold be designed to brn blended raw coal. It was therefore proposed that qality control shold be achieved by means of mine planning and operational control, together with large scale blending of the potentially very variable raw coal. To achieve the optimm prodct qality, it was fond necessary to mine, bt exclde from the spply to the Power Plant, a qantity of "Low Grade Coal." It was proposed that this material be stockpiled for possible ftre tilization. The mining and Power Plant Schemes were sbseqently evalated by the Athority's Technical Review Board, who remitted certain items to the Athority for reconsideration dring the smmer of 979. These inclded the possible incorporation of a "Low Grade Coal Beneficiation" facility within the Mine Moth Materials Handling Scheme. Simon-Carves, who had given preliminary consideration to this in March 978, were engaged for this work..2 SCOPE OF REPORT It was necessary to ensre that any Low Grade Coal Beneficiation plant wold be an integral part of the materials handling, screening and crshing facilities. The selection and layot of some eqipment within the previos scheme was also sbject to review by the Athority. Simon-Carves' scope of work was therefore widened to inclde assistance in aspects of this review. This enabled Simon-Carves knowledge of coal processing and handling to be'of particlar relevance. This Report therefore considers the selection and design of the.conveying, screening and crshing facilities for all mine prodcts. The overall scheme now incldes facilities for beneficiation by dry screening of the Low Grade Coal.

6 ,. ~.., L F490 ~ ~,,..),,.. BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme -2 ( SECTION INTRODUCTION ii Ii Ii.3 ACKNOWLEDGEMENTS In addition to relevant sections of the Jly 978 Mining Feasibility Report, and the Athority's September 978 Composite Report "Appendix D - Coal Qality and Handling", Simon-Carves also had access to other docments which are acknowledged in Appendix VI - Bibliography. This stdy was accomplished in a short time by close working contact' and detailed discssions with the staff of the Athority's Mining Department.

7 F490 BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme 2- SECTION 2 SUMMARY The layot of the Trck Dmp and Primary Crshing Stations in the Mine has been revised in principle to give greater operational flexibility. In particlar, it will be practicable to tilize alternative crshing eqipment to sit the variety of materials which are to be mined. Each mine conveyor now has a designated normal dty. Following blk density tests, it is recommended that all conveyors be increased to,400mm (54") wide. The potential beneficiation of Low Grade coals by means of dry screening, wet screening and washing has been frther evalated. It is conclded that wet methods will give formidable tailings disposal problems, bt that a sefl degree of beneficiation can be simply achieved by dry screening. The layot of the screening and secondary crshing plant has been completely revised to provide beneficiation by dry screening of Low Grade coal. Also, dplicate conveyor lines from the plant will allow simltaneos transfer of lower grade coals to the blending system and by-passing of High Grade coals to the Power Plant. Recommendations are given for frther testwork related to the crshing characteristics of all the materials to be mined.. this having been emphasized in the replies received from proprietary eqipment manfactrers. Eqipment sed in the preliminary scheme is of established designs in crrent commercial se. Attention is drawn to nits being developed which may be more sited to the reqirements. The niqe characteristics of the Hat Creek coals necessitate frther testwork prior to the design of any Low Grade coal beneficiation facility. It shold be noted that no samples have been obtained which have been proved representative of the blk of this material.

8 c c F490 BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme.., 3-, I, li LJ ti ii 7 li 3. INTRODUCTION DESIGN HANDLING, SECTION 3 REQUIREMENTS OF MATERIALS SCREENING & CRUSHING SYSTEMS This section of the report considers the varios materials which will be prodced in the mine, and the facilities reqired to deliver them to the appropriate tilization points. Prodction data is taken from the Cominco-Monenco Joint Ventre Mining Feasibility Report, Volme III, Mine Planning. Frther nderstanding has been obtained of the proposed operations by discssion with B.C. Hydro Mining Engineers. However, the basic scheme proposed by C-MJV is nchanged. It wold not be feasible'to make major changes withot access to the total stdy of the trck/shovel mining method. This stdy is therefore limited to reviewing the selection and basic design of specified elements of the system: 3.2 RUN-OF-MINE MATERIALS Dmp Pockets and R.O.M. Crshers Width and Speed of R.O.M. Conveyors General Arrangement of the Coal Preparation Area, with particlar reference to the Low Grade Coal. This stdy has identified eight distinct rn-of-mine materials which may reqire separate handling from the mine. Each of these materials may pose different handling problems in winter and smmer conditions. Their characteristics may also be significantly different when mined from dewatered areas below the. existing water table as compared with initial prodction in comparatively dry conditions. For this reason it is necessary that the handling system design can be modified as the mine develops Waste The largest volme of rn-of-mine materials will be waste spply described as a mixtre of yong sha,les with clay bands. This waste is therefore soft compared with that from most coal mining operations, and will break readily in crshing. The varying clay content will case bild-p of fine material in hoppers: chtes and within crshing eqipment. The ability of bentonitic clay to absorb moistre means that this material will not be effectively dewatered by the mine draining operation.

9 G F490 BCHPA - Hat Creek Materials Handling, Screening K Crshing Scheme 3-2 SECTION 3 DESIGN REQUIREMENTS OF MATERIALS HANDLING, SCREENING & CRUSHING SYSTEMS 3.2 RUN-OF-MINE MATERIALS - cont Waste for Constrction Clay Some clay free waste which will need to be segregated for mine road, waste dmp dam, and other constrction reqirements, comes particlarly from areas of glacial till to be removed at an early phase of the mine. Some of this material cold therefore be trcked directly to the point of se rather than delivered throgh the main waste conveyor system. Laroe bolders which wold reaire ~a- ~~~~~ special crshing eqipment may also be handled at lower cost by direct trcking from the mine. An area of massive clay with a high water content has been identified in Medicine Creek. This will reqire prpose designed.,.*. handling and crshing involving a minimm of cntes Normal Coal The blk of the rn-of-mine coal is expected to contain varying proportions of soft shale and clay materials. When dry this material has been observed to crsh and handle with ease. However, the large scale mining operation reqiring dewatering of mch of the coal strata means that it will have a significant srface moistre content. The design of the normal rn-of-mine coal system mst therefore be based on criteria for coals classed as difficlt. It can be anticipated~that in the early stages of the mine development the proportion of material with a difficlt handleability will be qite low, and therefore a program of progressive improvements to the handling system throgh the mine life is possible Petrified Wood in Normal Coal Petrified wood has been identified as present in significant qantities in areas of the coal strata. Rn-of-mine coal maytherefore need to be selectively crshed to reject this material.

10 F490 BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme c Ii 3.2 RUN-OF-MINE MATERIALS - cont. SECTION 3 DESIGN REQUIREMENTS OF MATERIALS HANDLING, SCREENING & CRUSHING SYSTEMS High Clay Content Normal Coal In some areas there are thick bands of clay in the coal strata which it wold not be economic to separate by selective mining. Coal handling systems mst therefore accept this material High Grade Coal The D Zone will provide coal of lower slphr content and higher calorific vale. This may need to be segregated in the mine and conveyed separately to the Power Plant either to assist in achieving high power otpt despite mechanical problems, or to facilitate the lowering of slphr dioxide emissions in adverse climatic conditions Low Grade Coal Low Grade Coal will have to be segregated in the mine and separately handled to a beneficiation system if the reqired Normal Coal qality is to be maintained.,this material is some 7% of total coal prodction over the mine life. 3.3 MINE CONVEYOR SYSTEMS The varios rn-of-mine materials described in the previos section have been considered with respect to their prodction rates and system reqirements to minimize stockpiling and effect segregation. A minimm of three mine conveyors are reqired. These conveyors, with their particlar feed and rn-of-mine crsher system designs, shold be dedicated to specific dties: Normal Coal Conveyor This system wold be in continos operation handling coal prodction from all for coal zones (A,B,C and D). Rejection of petrified wood mst therefore precede this conveyor. High clay content raw coal will also follow this rote.

11 .~,,~. :,,, c cl ( L L U L U U 0 U L U U L F490 BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme 3.3 MINE CONVEYOR SYSTEMS - cont. SECTION 3 DESIGN REQUIREMENTS OF MATERIALS HANDLING, SCREENING & CRUSHING SYSTEMS Waste and Clay Conveyor This conveyor rote to have a minimm of transfer points of the simplest possible design : ie. no two-way transfer chtes and vertical drop feed from one conveyor to the next Low Grade Coal/Spare Conveyor In addition to its primary dty, this conveyor wold provide a standby for either normal coal or normal waste. Consideration of the qantities of normal waste material to be removed, and the prodction pattern of low grade coal in certain periods (eg. years 4 to ) leads to the recommendation that a forth conveyor be installed at least from the pper level of the mine: Normal Waste Conveyor This conveyor to take the blk of dry waste from pper levels of the mine, ths giving more flexibility in the se of and Each conveyor system is based on 3,000 cbic meters per hor, ie. p to 3,200 tonnes per hor of coal, 5,000 tonnes per hor of waste. The position of the conveyors fin the mine has not been altered. Ths the mine dmp pocket system proposed by C-MJV can be retained. With the designated conveyor dties proposed above the conveyor centre-lines are acceptable. Measrements of the blk density of coal and waste samples confirmed the swell factors sggested by Weirco. The mine conveyors recommended are therefore 400mm wide (54 inches) operating at 4.5 meters/second. This width is also recommended within the Coal Preparation Area, with the speed redced to 2.5 meters/second for the 000 tonnes per hor conveyors feeding to screening eqipment. 3-4 L

12 0 F490 BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme 3-5 c, 0 U U U U U U U U U U 3.4 PRIMARY CRUSHING STATIONS SECTION 3 DESIGN REQUIREMENTS OF MATERIALS HANDLING, SCREENING & CRUSHING SYSTEMS The selection of eqipment and design of these stations mst take accont of the characteristics of the materials identified in Section 3.2. Crshing tests have been limited to the breaker drop tests condcted by Fawcett, and testwork by manfactrers of other specialist types of crshers is essential. Representative samples of as mined materials of the'more difficlt categories below water table level will not be available ntil the mine has been in operation for some years. Preliminary design of the primary crshing systems shold therefore allow for the sbstittion of alternative crshing systems. (Note that the C-MJV layot can be sed only with the Siebra type). Review of available crshing systems confirms that 500 cbic meters/hor is a practical maximm for most manfactrers and the designs considered in this report are based on this throghpt. Feed cold therefore be received simltaneosly from two dmp stations to each conveyor. Consideration of desirable maximm particle size together with wear and'tear in sbseqent handling, screening and secondary crshing operations,redce the rn-of-mine material to below 200mm. This wold also facilitate rejection of more nwanted material, eg. petrified wood, than the 300mm previosly sed Dmp Pockets Each Dmp Pocket to hold approximately three trckloads to permit smooth trnarond of mine trcks. De to the sticky clay problems we are recommending steeper slopes than normally encontered, and cold not recommend the se of box shaped pockets (ie. where the fall of large lmps is broken by a static bed of material).

13 F490 BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme 3-6, SECTION 3 DESIGN REQUIREMENTS OF MATERIALS HANDLING, SCREENING & CRUSHING SYSTEMS 3.4 PRIMARY CRUSHING STATIONS - cont. ij I 0 0 c Dmp Pockets - cont. Some crsher manfactrers claim to accept lmps of the maximm anticipated dimensions withot a grid over the hopper. (For example, in Hazemag's System there is a "breaking access trap" for oversize lmps). We consider it is ndesirable to ooerate with no top size restriction, and have retained the 600 x 600mm grid size from which gross oversize pieces will have to be removed, for example by front end loader. (Consideration shold be given from a personnel safety aspect to sing a 450 x 450mm grid. Also, it shold be noted that if this size were adopted it wold be possible to convey from the dmp pocket discharge to crshers sitated directly over the appropriate mine conveyor. However, the 450 x 450mm grid cold retain nacceptably large qantities of material for removal) Rn-of-mine Feeders Vibrating feeders are not sfficiently powerfl or robst for this dty. The variable speed apron feeder is most widely sed. Most manfactrers of psh-plate type feeders do not have large enogh nits available. This feeder has the disadvantage of losing height, whilst the apron feeder can elevate. However, Hazemag have a large capacity hydralically operated feeder which is inclded as part of their System package Rn-of-mine Screens It is desireable to remove ndersize to redce the load on the crsher - particlarly when sticky fines are present - and to avoid excessive breakage. The Krpp Roller Screen is an integral partof-the Siebra Crsher. This type of self-cleaning screen has a good reptation for operating on sticky feeds, and has the mechanical strength to accept large heavy lmps. The geared drive mechanism of the Krpp mst be a high initial cost component.

14 F490 BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme 3-7 SECTION 3 DESIGN REQUIREMENTS OF MATERIALS HANDLING, SCREENING & CRUSHING SYSTEMS 3.4 PRIMARY CRUSHING STATIONS Rn-of-mine Screens cont. - cont. The Pettibone Wobbler Screen appears to be a viable alternative. The "wobbler" screen blades shold provide an enhanced cleaning action. The chain drive shold be cheaper yet present few problems. Generally, vibrating screens are not sfficiently robst for these dties, and jigging screens wold be of large nit size. Sch conventional screening machines also lose height compared with the horizontal roller screens. We have, however, inclded a Simplicity vibrating screen which is standard in the Hazemag System package Rn-of-mine Breakers Bradford Breaker This is a volminos machine best fed by conveyor with a preferred maximm lmp size of 450mm. Rejection of hard material sch as petrified wood wold be readily accomplished. It is likely, however, that there is also hard coal, which wold be rejected. The.drop shatter tests by Fawcett also sggest that some goody coal may be lost. The Bradford Breaker at Centralia has been observed to reject clay l~mps from wet mining conditions similar to those anticipated from lower mine levels. Experience at Coal Valley, Alberta has inclded problems with bild-p of wet clay fines on the otside of the drm and in the prodct collecting chtework. To clear these with qantities of water - as at Centralia - wold be nacceptable nless all coal is to be washed.

15 ,_~,..,.~..;.:. 7 F490 BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme 3-8 SECTION 3 DESIGN REQUIREMENTS OF MATERIALS HANDLING, SCREENING & CRUSHING SYSTEMS 3.4 PRIMARY CRUSHING STATIONS - cont Rn-of-mine Breakers - cont Krpp Siebra Crsher This nit is sccessflly sed in the Lignite Indstry. It is able tom reject the petrified wood. There may be problems with clay sticking in the crshing rollers. We endorse the reservations listed in correspondence to yo by Krpp Indstries. However, at this stage and sbject to testwork, we propose this machine for Normal Coal, and particlarly for the Normal Coal with Petrified Wood. It is necessary to have an alternative available shold the wet clay be problematic Wing Crsher The Hmboldt Wing Crsher is also widely sed in the Lignite Indstry, bt it cold not accept hard waste, particlarly Petrified Wood. Impactors The wide range of applications of this design sggests it will be able to accept all Hat Creek materials, except massive clay. Hazemag are the only manfactrer to offer nits large enogh for the rn-of-mine dties. Different speeds are reqired for alternative dties, ie. higher speeds for Waste with clay, to give sfficient breaking and cleaning forces, lower speeds for coal withot waste to minimize degradation. Hazemag sggest tests shold reveal a degree of selective crshing, which cold achieve rejection of petrified wood if followed by screening. The Hazemag design can be fitted with heated impact srfaces which wold release wet clay. We propose these machines with provision for the oil heating system be added if and when reqired. It also may be easily opened for cleaning.

16 G F490 BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme 3-9 SECTION 3 DESIGN REQUIREMENTS OF MATERIALS HANDLING, SCREENING & CRUSHING SYSTEMS 3.4 PRIMARY CRUSHING STATIONS - cont Rn-of-mine Breakers - cont. G ill il Impactors with Moving Breaker Plates Machines of this type are in wide se with sticky materials. The Jeffrey Md Hog has the advantage of reversible feed/breaker plates, and has been sed in clay breaking as well as a variety of sticky coal and waste applications. Pennsylvania Crsher's Non-clog Hammermill also has an optional moving back-plate. With both of these machines, the breaker plate helps to feed the material into the impactor path. The Blldog Non-clog Impactor type Hammermill appears to offer the best layot, however, since the breaker plate is near vertical, and the feed drops vertically onto the impactor as compared with the approximately 45' feed of the Jeffrey and Pennsylvania machines. Blldog's breaker plate may be inched away from the impactor for cleaning the machine, and it also has an optional moving back-p plate Clay Feeder/Shredders J.C. Steele (and others) manfactre a clay feeder in which a set of screws at the base extrde clay and deliver in a shredded form. These nits have a low capacity - say 00 tonnes per hor and are designed for the clay indstry. The major restriction to se of these machines is that they may be blocked p or even damaged by stones. We cannot therefore recommend these nits for the clay waste.

17 F490 BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme 3-0 SECTION 3 DESIGN REQUIREMENTS OF MATERIALS HANDLING, SCREENING & CRUSHING SYSTEMS 3.4 PRIMARY CRUSHING STATIONS General Design - cont. We recommend that the Rn-of-mine Breaker stations be designed for location on the side of benches on either side of the mine conveyor system. Prodct conveyors wold deliver to the mine conveyors with the facility by means of change-over chtes to deliver to either of a pair of mine conveyors. Ths, for example, a given system cold deliver to the Low Grade Conveyor or Waste Conveyor. This will redce the nmber of Dmp Pockets reqired in the mine. The other advantage of this layot is ease of access for maintenance of the feeders, screens and crshers, and the possibility of changing the type of crsher at a given point if changes in dty so reqires. 3.5 COAL SCREENING AND SECONDARY CRUSHING 3.5. Introdction The 2OOmm x 0 raw coal has to be crshed to below 50mm for delivery to the Power Plant. To redce load on the crshers, and to minimize breakage, it is desirable to screen ot the ndersize at 50mm prior to crshing. The low grade coal may also be partially beneficiated by screening at say 3mm and rejecting the fines to waste. This section reviews the dry screening and crshing nits which may be applicable for these dties. Prior to screening and crshing,hoppers are proposed for the following reasons: - to give a more even feed to the nits - to permit emptying of the mine conveyors in the event of prodct conveyors, crshers or screens shtting down - to divide the feed between modles so as to redce size segregation and maintain efficiency i'.<.. The se of~rotating chtes to feed the hoppers will distribte the feed'between'modles and so-give some degree of mixing prior to the screening and crshing operations. It shold be noted'that a degree of melting will take place by virte of~the rotating chte.

18 F490 BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme 3- SECTION 3 ~ DESIGN REQUIREMENTS OF MATERIALS HANDLING, SCREENING & CRUSHING SYSTEMS 3.5 COAL SCREENING AND SECONDARY CRUSHING - cont Coal Screening In selecting machines for these dties, we have been conscios of the need to base design on proven eqipment at this stage. Developments in thisfield are also reviewed. Conventional screens have been incorporated in the layot becase the other types of screen reviewed have not yet been proven Conventional Screens There shold be no problems in sing heavy dty 50mm x 50mm woven wire for removing ndersize prior to the crshers. Partial blinding of the screen srfaces may occr when the wet clay content is high, bt the presence of 200mm particles will keep this to an acceptable level. A safety factor has been sed in determining the crsher capacity. The tonnages to be handled are within the capacity of conventional screens. There are many manfactrers : Allis-Chalmers Ripl-flo is widely accepted. The largest nit size is 8 ft. wide x 20 ft. long. It is believed that these screens wold be the most sitable for this application. Consideration was given to the larger nits now available, eg. the Siebtechnik Banana Screen. This wold redce the nmber of nits, bt more extensive chtework to collect prodct and feed crshers is reqired. This also redces the flexibility which can be achieved by a modlar design. Woven wire or similar decks wold not be sitable for screening at -3mm de to blinding when the feed is sticky Heated Deck Screens Electrically heated decks have been sed on moist coal feeds to permit more efficient dry screening in the 5 to 5mm size range. Maintenance may be high, particlarly reslting from accidental damage. Rod Deck Screens Screen decks consisting of rods free to trn and vibrate within oversize monting apertres are widely sed in the 20 to 8mm size range in Erope. They give acceptably efficient dry fines removal, and are low in maintenance cost de to being robst.

19 c d r F490 BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme ;I;, L I SECTION 3 DESIGN REQUIREMENTS OF MATERIALS HANDLING, SCREENING & CRUSHING SYSTEMS 3.5 COAL SCREENING AND SECONDARY CRUSHING - cont ~Coal Screening - cont Rod Deck Screens - cont. One problem is that they are very noisy in operation, and the screening section of the plant shold be isolated from continos operator access. L L II II , Crshing Probability Screens Vibrating screens sing a series of oversize decks which give effective fines removal by virte of the chances of passing nearsize particles forward to overflow have fond only limited application. The National Coal Board (U.K.) has recently developed a rotating probability screen which is said to give good separations in the 2 to 4mm range. The "deck" is a rotating spoked wheel : increasing the wheel speed redces the size of particle which passes throgh to ndersize prodct. Performance data has not been made available. These machines are crrently of low nit capacity, typically 00 tonnes per hor, and a complexity of plant ths makes these nits less attractive in total scheme cost. Disc Screens Radmark Engineering have recently developed a version of their disc screen for sizing in the 25 to Omm range. Simon-Carves assisted with test evalation, and a high throghpt per nit area was obtained. This nit is to be frther tested alongside probability screens in the U.K. and may be worth re-evalation for the Hat Creek project at a later date. 0 ~,L There are a wide variety of crshers available for redcing 200 x 50mm coal to below 50mm of similar design to the nits described earlier. We have selected the Hazemag Impactor with optional heated breaker plates as the best machine for the sticky feed conditions, with the Jeffrey Md-Hog a close second choice.

20 F490 BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme 4-l SECTION 4 BENEFICIATION OF LOW GRADE COAL BY WET PROCESSING 4. INTRODUCTION Representative areas of coal which have been designated as Low Grade have not been sampled and tested de to their location. There are two sitations which may give rise to this categorization: admixtre of reasonably good coal with a higher than normal proportion of free shale and clay. This might be fond for example as shaling ot of the coal measres at the fringes of the deposit. Sch raw.coal wold have a relatively good beneficiation potential : ie. cleaning wold give a prodct yield, albiet small, of relatively high calorific vale. raw coal with an even higher "impregnation" of clay in the particle fissres. This material wold have a very poor beneficiation potential. In the absence of any washability data of sch raw coals, this section is concerned with projecting the data obtained for the "Normal" Hat Creek raw coal. These projections show in fact the latter of the above alternatives. Therefore, washing the Low Grade coals wold reslt in a prodct of low qality, despite the removal in the washing process of proportionately large qantities of clay as tailings. A sb-sample of the Agst 979 Trench A Low Grade material was sbjected to wet screening and gives some confirmation of this, bt no definite case for wet processing of the low grade coal can be made ntil representative samples have been obtained. 4.2 BENEFICIATION BY DESLIMING Since the fines, say -28 mesh, are significantly higher in ash content than the coarse material, desliming the raw coal may give significant cleaning. Table 4-l shows vales which have been projected from the wet screening reslts obtained for the 977 Samples X and Y, the CANMET screening tests, and the 979 Low Grade Coal Sample.

21 TABLE 4- : BENEFICIATION OF LOW GRADE COAL BY DESLIMING cv BTU/lb ASH Prodct = Screen O/Flow Reject = Screen U/Flow 75% 25% Yield BTU of Yield CV,BTU/lb Ash % CV,BTU/lb Ash% % Beneficiation ~ '

22 F490 BCHPA - Hat Greek Materials Handling, Screening & Crshing Scheme 4-3 SECTION 4 BENEFICIATION OF LOW GRADE COAL BY WET PROCESSING 4.2 BENEFICIATION BY DESLIMING Desliming does offer a relatively sefl degree of cleaning for the lower plant costs involved and moderate loss of heating vale for rejects. All of these rejects mst be considered as tailings rather than a solid waste discard. Tailings dewatering and disposal has been considered in the main report on Coal Beneficiation, and the conclsion that this will present formidable problems applies eqally in this case. It is relevant to sggest that the recommended pilot plant work shold commence with,a simple desliming operation on Low Grade coal providing tailings for investigation. Once this problem has been resolved, circit refinements to give a degree of washing may then be evalated. 4.3 BENEFICIATION BY WASHING No Washability Data has been obtained for the Low Grade coals. Therefore, it is necessary to see how available data shows trends which may be projected into this qality range. Inspection of the Washability Data shows two general trends. a) Finer Sizes are dirtier than coarser sizes. b) For a given s.ize fraction the higher ash of the poorer coals is de to a lower proportion of low gravity (low ash) coal/higher proportion of middlings and not to an increase in the high gravity (high ash) clay/shale partings material. (Note that this is evidence that we are concerned with a trend in coal qality and not a trend in admixtre of even minte partings with relatively good coal. If the latter were the case, we shold, with appropriate crshing, have a coal with a relatively good beneficiation potential. Also, note that the washability data in the CANMET Wash Test shows no liberation by crshing).

23 3 ri F490 BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme.,. 4-4 SECTION 4 BENEFICIATION OF LOW GRADE COAL BY WET PROCESSING 4.3 BENEFICIATION BY WASHING - cont Plant Reqirements for Washing The two-stage Water-Only Cyclone System (eg. EMR Canmet) may be considered for washing the raw low grade coal crshed to 40mm. The main disadvantage of this system is that the mltitde of cyclone operations: feed classifying, first washing, second washing, and prodct thickening reqires large volmes of water in circlation. Operating costs for pmping are,ths high and the several passes with circlating water will give a high tailings problem as fond in the CSMT and EMR Test Washes and the Wet Attrition Tests. Large nmbers of cyclones are reqired de to their relatively limited rejects capacity (25 to 30% of feed). An alternative form of atogenos medim cyclone is available - the Simdex. The Simdex system was specifically developed for re-washing the rejects from inefficient plants or re-processing mine waste dmps. The Simdex ses the mins 28 mesh fine shale present to form a thick shale sspension in water which then acts in the cyclone as a dense medim for the 40mm x 28 mesh material. Since it was designed for waste coal treatment a Simdex Cyclone has some three times the rejects capacity of similar sized magnetite medim cyclone or water-only cyclone, and simpler liqids circit. The process does have disadvantages. Its efficiency is similar to two-stage water-only cyclones, and ths mch lower than conventional magnetite medim cyclones. The separation gravities attainable depend on the characteristics of the mins 28 mesh shale particles, and it is probable that the clay content of the Hat Creek coal wold be too high. U U U The Hirst Fine Coal Washer developed by the NCB (UK) has been sed for re-washing mine waste piles as well as Omm x 28 mesh fine coal. De to the low water reqirements, this nit wold also warrant consideration.

24 F490 BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme 4-5 SECTION 4 BENEFICIATION OF LOW GRADE COAL BY WET PROCESSING 4.3 BENEFICIATION BY WASHING - cont Plant Reqirements for Washing - cont. The modlar Coal Washery as presented in the Coal Beneficiation Report, with modifications to the fines circit, and extensive tailings facilities, cold also be sed. This wold, however, be a very expensive plant for the low recovery of coal obtained. From that stdy, an approximate cost estimate sggests a capital investment of $2 million, and an operating cost of $2.50 per ton of feed. (This does not inclde the cost of a dewatered tailings disposal area). This wold give a prodct cost of $6.50 per ton. It can be conclded that a washing scheme is nlikely to recover sefl coal at a cost comparable with mining the eqivalent tonnage of additional Normal coal. Althogh it wold be worthwhile investigating the performance of simpler process schemes designed specifically for this Low Grade material, the fact that the blk of the cost is related to tailings dewatering and disposal means that an economically sond proposal is improbable Projected Washing Reslts As the fines content increases and becomes dirtier the potential coal recovery from the finer sizes is very low. Therefore, it is not necessary to consider any washing of the mins 28 mesh material. In Table 4-2 below it can be observed that the "yield error" (Theoretical Yield - Actal Yield) is high de to the difficlt washability characteristics. Projecting reslts for the Low Grade coal therefore gives a very poor retrn for the cost of washing. Similarly the reconstitted data from the CANMET Wash Test shows, for the 3/8" x 28 mesh size fraction a theoretical yield of 86.0% at 7.3% ash, bt an actal yield of 75.6% from the 24.2% ash raw coal. Table 4-3 shows vales projected for the Low Grade coals in the 2000 to 5000 BTU/lb range.

25 li F490 BCHPA - Hat Greek Materials Handling, Screening & Crshing Scheme 4-6 c ) I BENEFICIATION SECTION 4 OF LOW GRADE COALS BY WET PROCESSING c TABLE 4-2 : BENEFICIATION POTENTIAL OF l/4" x 28 MESH COALS - SEPARATION IN TWO-STAGE WATER CYCLONES SAMPLE % ASH OF RAW COAL CLEAN COAL, k" x 28 MESH % YIELD 4" x 0 k" x 28M % Theoretical Actal 0 2 C L B x+y Li A c c ;

26 TABLE 4-3 : BENEFICIATION OF LOW GRADE COAL BY TOTAL WASHING RAW COAL CLEAN COAL PRODUCT cv ASH YIELD ASH cv BTU/lb % d.b. wt % % d.b. BTU/lb REJECTS INCLUDING TAILINGS BTU Degree ASH cv Yield % of % d.b. BTU/lb Beneficiatior i NOTE: These reslts do not inclde allowance for the "yield error" of the washing processes. Based on the probable se of a water-only washing cyclone system this wold involve a redction of abot 0% in the yield, eg. for a 3,000 BTU/lb raw coal the actal yield wold be 40.0% by weight, the BTU yield 69.8%.

27 F490 BCHPA - Hat Creek Materials Handling; Screening & Crshing Scheme 5- SECTION 5 BENEFICIATION OF LOW GRADE COAL BY DRY SCREENING 5. INTRODUCTION Or March 978 Interim Report considered varios sets of washability data from samples B, Y, X and A. Ash content verss size consist was plotted for each of these samples. A similar geometric trend was observed and frther crves were pro.jected to general relations for coals of 4500, 3700 and 3000 ETU/lb. Additional data was available for this stdy which inclded the CANMET Test data, an independent sample taken in 977, and the two new samples of Low Grade Coal taken in Jne/Jly 979. This additional data was plotted sing the same parameters as previos stdy work. The X and Y samples' data was combined in a 50/50 ratio and the composite data set was treated as a single set of data. Data from Sample C was also considered in this stdy. 5.2 THEORETICAL BENEFICIATION Table 5-l shows the theoretical reslts of dry screening varios coals ranging in calorific vale from 2000 BTU/lb to 6000 BTU/lb in increments of 500 BTU/lb. The corresponding ash of each coal qality was calclated sing the revised ash/calorific vale correlation eqation. It was assmed that the size of classification wold be chosen sch that 50% of the feed wold report to overflow and a like amont to nderflow. The average ash differential for a 50% classification is 6.84% (See Appendix III). Therefore? the screen overflow ash will be 6.84% cleaner than the feed ash. Similarly, the screen nderflow ash will be 6.84% dirtier than the feed ash. These theoretical ashes were applied to each raw coal qality and the corresponding calorific vales were calclated sing the given calorific vale/ash correlation eqation.

28 TABLE 5- : BENEFICIATION BY SCREENING OF LOW GRADE COALS (THEORETICAL) BT$b RAW COAL PRODUCT = SCREEN O/FLOW REJECT =~'SCREEN U/FLOW - 50% 50% YIELD D&E': j% iitu ASH cv ASH ASH RECOVERY % d.b. BTU/lb % d.b. BT&b ~% d.b. BENEFI::ATION'

29 F490 BCHPA - Hat Creek Materials Handling: Screening & Crshing Scheme 5-3 SECTION 5 BENEFICIATION OF LOW GRADE COAL BY DRY SCREENING 5.3 PREDICTED BENEFICIATION Note that the above exercise did not consider the effects of screening inefficiency. Varios data was collected regarding the partition factors applicable to dry screening operations as accmlated over the years. After considerable assessment and collation of this information a series of partition factors was calclated. These factors were then applied to the anticipated size consist of the feed. The partition factors for the screening operation were applied against the anticipated size consist (see Appendix III) to determine the distribtion of material in the screening operation. The screen overflow and nderflow qalities were predicted by applying the overflow and nderflow qantities against the ash distribtion. The ash distribtion sed was the same as that for the theoretical predictions. Table 5-2 below shows the predicted screen overflow and nderflow ash and calorific vale for varios coals ranging in qality from 2000 BTU/lb to 6000 BTU/lb in 500 BTU/lb increments. To frther illstrate the beneficiation potential shown in Table 5-2, sing dry screening consider the following example. Consider the case of a feed of 400 tonnes corresponding to the top for rows of Table 5-2, viz 2000 BTU/lb, 2500 BTU/lb etc. Assme that the qality of the prodct is eqally distribted throghot. If no screening were applied, the yield wold be 400 tonnes at 3000 BTU/lb ie. the average calonfic vale of the feed. If a manal "Ct-off" of 3000 BTU/lb was applied to this feed, 50% wold be rejected viz 2000 BTU/lb and 2500 BTU/lb, as being below grade. Therefore the yield wold be 200 tonnes at 3500 BTU/lb ie. the average calorific vale of the acceptable qality prodct. If dry screening were employed with only the screen overflow monitored by a Blk Density Meter, the yield wold be tonnes at 346 BTU/lb. If dry screening were employed with Blk Density Meters measring ash of both the screen overflow and nderflow prodcts, the ~"ct-off" wold be applied to each of said prodcts simltaneosly. With the overflow meter set to "ct-off" at 3000 BTU/lb, the prodct yield wold be 79 tonnes at 3740 BTU/lb. Similarly, with the nderflow meter set at 2540 BTU/lb, the yield wold be 68.6 tonnes at 2896 BTU/lb. Together this wold represent a yield of tonnes at 3506 BTU/lb.

30 TABLE 5-2 : BENEFICIATION BY SCREENING OF LOW GRADE COALS PREDICTED FOR 20MM APERTURE RAW COAL PRODUCT = SCREEN O/FLOW REJECT = SCREEN 6.9% 38.% YIELD cv ASH ASH cv ASH BTU/lb % d.b. BT&b % d.b. BTU/lb % d.b. DEGREE OF BENEFICIATION % BTU RECOVERY

31 c L F490 BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme 5-5 ~ c L, SECTION 5 BENEFICIATION OF LOW GRADE COAL BY DRY SCREENING t 5.3 PREDUCTED BENEFICIATION - cont. This clearly illstrates the advantage of beneficiation by dry screening in conjnction with Blk Density Meters monitoring prodcts. The above calclations assme that the manal "In-pit" section of the Normal/Low Grade and Low Grade/Waste ct-offs at 4000 and 2000 BTU/lb are effected with 00% accracy. In practice, this wold present a formidable operating problem. The overall advantage of sing the Blk Density Meters illstrated above will be magnified several times when practical flctations in this In-pit selection are taken into accont. In fact the only reslt which cold be applied with reasonable confidence is the se of Blk Density Meters monitoring both screening prodcts. In practice all material for example between 5000 BTU/lb and waste observed to contain some coal cold be directed to the Low Grade Coal circit for atomatic optimization of recovery. This will greatly ease problems of mining system control. The Blk Density Ash Meters will need to be monitored and adjsted reglarly to take accont of variations in material characteristics. If the Normal coal is directed via the No. Prodct Conveyors to the Blending Stockpile, and the No. 2 Prodct Conveyors are sed only for the selected Low Grade coal prodct, the No. 2 Continos Ash Meter will provide this monitoring facility. L 5.4 PLANT REQUIREMENTS The eqipment reqirements forscreening and crshing have already been considered in Section 3. A proposed scheme has been otlined based on these findings, and integrated into the Normal Coal handling, screening and crshing scheme. This is described in Section 6.

32 0 0 c F490 BCHPA - Hat Creek Materials Handling; Screening & Crshing Scheme 6-l SECTION 6 DESIGN AND COST OF SCHEME 6. BASIS OF DESIGN This scheme has been designed to provide capacity for the removal of 9000 m3/hr. of material from the mine. Blk density of the material to be removed ranges from 800kg/m for coal to 600kg/m~ for waste. Material to be removed will fall within this range. The scheme has provided tor 400mm wide conveyors rnning at 4.5m sec. to'handle this capacity L L The original stdy called for three conveyors pls a ftre standby. conveyor to perform the above described dty. These conveyors were to be completely interchangeable, that is, able to handle coal, waste, or a combination of both. However, the revised scheme, in order to maximize the availability and sitability of the conveying systems, has individal conveying systems for individal conveying dties. The separation of the conveying systems by the prodcts being carried has not been at expense of operating flexibility. The proposed conveying systems fall into two discrete categories, namely coal and waste. The coal conveyor ot of the mine will handle coal only. A second conveyor will handle waste and clay only. A third~conveyor will provide back-p waste capacity for the second conveyor bt withot provision for handling clay. The forth conveyor will be capable of being a standby coal conveyor and standby waste conveyor in addition to being the low grade coal conveyor. All conveyors are capable of transporting o to 300 m3/hr. This corresponds to the eqivalent of 5000 tonnes/hor of waste and 3200 tonnes/hor of coal. The coal,handling system at the mine moth has been designed for two grades of coal, namely normal coal and low-grade coal. The former system has been designed for 3200 tonnes/hor and incorporates for streams each capable of 000 tonnes/hor. The low-grade screening and handling system is designed for 000 tonnes/hor and consists of two streams each capable of 500 tonnes/hor. The normal coal screening and crshing with for modles rated at 000 tonnes/hor each is designed to crsh 350 tonnes/hor per stream. The anticipated size analysis predicts that only 200 tonnes/hor is reqired, and therefore a coarser size analysis cold be catered for.

33 F490 BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme 6-2 SECTION 6 DESIGN AND COST OF SCHEME 6. BASIS OF DESIGN - cont. The in-pit primary crshing systems have been designed for the individal materials. The normal coal trck dmp station will employ a 600mm sqare grizzly above the 300 tonne capacity srge hopper. Crshing will be attained sing a Siebra type crsher with capability for selective crshing. The waste and low grade coal crshing systems employing a similar grizzly will crsh sing an Impact type crsher. The 600mm sqare grizzlies on the trck dmp hoppers will limit the maximm particle size to any specific crsher to 600mm x 600mm x 200mm. 6.2 DESCRIPTION OF SELECTED SCHEME This description shold be read in conjnction with drawing F Normal Coal Normal coal will be delivered to one of the normal coal trck dmp stations and deposited in the srge hopper. Reclaim from. said hopper will be by apron feeder discharging onto a roller screen working in conjnction with a Siebra type crsher. The roller screen.will effect a size classification allowing smaller particles to pass throgh the rollers. Larger particles will be redced in size by the overhead crshing mechanism. This mechanism will be designed to allow large pieces of ncrshable material sch as petrified wood to pass nder itself by lifting p. Therefore these large pieces of hard material will be discharged onto a conveyor for transport by trck. The coal, either passing freely throgh the roller screen or redced and forced throgh, will be collected on a transfer conveyor for delivery to the Normal Coal Conveyor. This conveyor will transport the normal coal from the mine and deliver to the Mine Conveyors Drive and Transfer Hose. From this point the coal will be transferred onto a second Normal Coal Conveyor for delivery to the Normal Coal Srge Bins. A rotating chte will distribte the coal feed eqally into for bins.

34 F490 BCHPA - Hat Creek Materials Handling, Screening & Crshing Scheme 6-3 SECTION 6 DESIGN AND'COST OF SCHEME cl Ii.[I : Ii 6.2 DESCRIPTION OF SELECTED SCHEME - cont Normal Coal - cont. Reclaim from each of the above for bins will be by apron feeder. Each feeder will discharge onto a conveyor delivering to the Screening and Crshing Hose. The coal will be discharged from each delivery conveyor onto a two-deck inclined vibrating screen. The top decks of these for screens will be fitted with 50mm sqare woven wire srfaces to effect size classification at 50mm nominal. The lower deck will be fitted with mild steel plate and fnction as a carrying deck. Screen overflow will be discharged into an impact type crsher for redction to mins 50mm. Screen nderflow will be carried forward to blend with the crsher prodct. The mins 50mm normal coal will gravitate into a bifrcated chte for diversion to either the No. or No. 2 Prodcts Conveyors. The No. and No. 2 Prodcts Conveyors will rn parallel to the Transfer Hose where the coal will be transferred to a second parallel pair of conveyors. These second No. and No. 2 Prodcts Conveyors will deliver the coal to the Sampling Hose. A frther transfer of the coal onto a third pair of Prodcts Conveyors will occr in this hose. These conveyors will deliver the coal to the Blending Piles Feed Conveyor or the Reclaim and Bypass Conveyor Low Grade Coal Low grade coal will be delivered to one of the low grade coal/waste trck dmp stations. These trck dmp stations will also be capable of accepting waste material or coal. The trck dmp hopper will be fitted with a grizzly having 600mm sqare openings. Material in the hopper will be reclaimed by a reciprocating psh feeder and discharged onto a cascading vibrating grizzly having 200mm sqare openings. The grizzly overflow will be discharged into an impact type crsher for size redction to,mins 200mm. Grizzly nderflow together with the crsher prodct will gravitate onto a transfer conveyor for transport to either the standby waste conveyor or the low grade coal conveyor. A bifrcated chte will divert the material to either conveyor depending on qality.