The Asia Miner

OCT-DEC 2017

The ASIA Miner - Reporting Important Issues to Mining Companies in the Asia Pacific Region

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Page 48 of 55

Volume 14 • Issue 4 | 2017 | ASIA Miner | 47 Supplier News we were seeing significant breakage taking place from repeated passage through the materials handling system. Because of this, no further adjustment was made and the remaining drums were sorted. The product and reject streams were packaged to be returned to the laboratory and were subjected to Float/ Sink testing. Yields and product ashes are presented in the table, along with partition parame- ters and calculated misplacement of coal and reject. The partition curves developed from the laboratory float/sink data show acceptably sharp separations, as denot- ed by the Ep values. The Ep value is a measure of departure of the centre portion of the partition curve from the vertical (a vertical curve would represent a theoreti- cally perfect separation). The lower the Ep value, the sharper the separation. Across the two size ranges tested, the pilot X-Ray sorter removed a combined total of 20.6% of the ROM tonnes as rock directly to reject. The targeted outcome was demonstrated and the overall pilot project objective has been successfully achieved with a number of notable ben- efits. The most effective benefit from raw coal upgrade occurs when treating the poor quality seams. There is also a potential metallurgical im- provement within the separation process itself. When treating poor quality (that is low product yield) coals, the quantity of reject material that has to discharge from the Dense Medium Cyclone (the major separa- tion device in the plant and the one which treats the coarse material) is large and can lead to some of that material reporting to product when all of it should ideally go to reject. Under such circumstances, this inclusion of reject in the product will increase the product's ash content requiring the DMC's separating density to be lowered in order to maintain product specification. Lowering separation density will reduce yield. For poor quality coals, where we see X-Ray sorting being of most benefit, remov- al of stone beforehand can reduce or even eliminate this effect. Eliminating stone from the CPP feed is equivalent to an increase in plant capacity, ie remove a tonne of stone from the feed and replace it with a tonne of coal. Put simply, using this sorting technique is attractive to us because it means we can put a higher quality raw coal through the CPP, which in turn means a higher yield. Ba- sically, by sending some of the coal through this sorter first, our CPP would be doing less work getting rid of reject, and more work processing product coal. Right now we're evaluating the outcomes from phase one of the trial. Ideally we would like to go to the next stage of the trial which could potentially see us bring a sorting unit onsite to New Acland. Using the new tech- nology at the mine site will let us test it on a large scale and test how it interacts with the rest of our CPP operations. The Bayswater pilot testing unit is similar in most respects to a commercial size unit, but has a 1-metre wide feed belt while the commercial units have 2-metre wide belts. What we would like to do is put the tech- nology to use in a full-scale, commercial operation. The pilot scale unit is restricted in the upper particle size it can treat, notion- ally 150mm; commercial sorters can treat particles in excess of 200mm. As well as this, the pilot testing unit's feed system is not continuous, but treats batches of test material. Recommendations from the equipment supplier suggest that particle size range should ideally not exceed 3:1. This require- ment was factored in to the selection of the size ranges investigated. Sorting occurs at a very rapid rate, based on high speed electronics and air impulse valves.

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