CDE Global, a specialist in the construction of sand mining wet processing plants, has undertaken the independent processing test work, process circuit design and engineering.
The plant design incorporates features to ensure high utilisation and performance with duplicated critical pumps and variable speed drives on all pumps.
Three iterations of test work have been carried out on the Arrowsmith and Muchea projects, 270km and 50km north of Perth respectively. According to VRX Silica (VRX), the attritioning cycle has been demonstrated to be particularly effective in removing impurities from the quartz grains.
VRX personnel have reported that the plant design for the production of a high purity silica sand product is suitable for the glass-making industry. CDE Global estimates that the cost of constructing the modular two million tonne per annum processing plant will be about $18.2 million.
According to VRX, estimates costs for the plant feeder, water supply and contingency will increase the total capital cost for a processing plant to around $25 million. Further testing is underway to finalise the requirements for the magnetic separation component (WHIMS), but this isn’t anticipated to materially affect the costs.
The processing plant will wash, screen and attrition sand and remove heavy minerals to create a final product for delivery to customers. There are no chemicals required for the process, which includes a thickener that will allow for 95 per cent of process water to be recycled.
The process flow for the plant will be as follows:
- An upstream process, which will provide a slurry feed product with solids of a maximum 2mm size. The product is classified by a series of screens that will create a coarse product (<2mm – +0.6mm) and a fine product (-0.6mm).
- The coarse product is washed, dewatered and stockpiled.
- The finer product moves to an attrition scrubbing and washing process.
- Finer product then moves on to a spiral bank separating the feed into heavies and lights.
- The light product passes through a magnetic separation process.
- Non-magnetic product moves to a counter flow classification unit (CFCU) which produces two products:
(a) A glass sand product (<0.6mm + 0.212mm).
(b) A fines product (<0.212mm + 0.06mm) that will be sent to the coarse sand stockpile.
- Slimes less than 75um produced by the plant will be treated through an AquaCycle thickener for process water recovery.
In addition to confirming the processing plant design, VRX Silica will continue to assess various options for associated production and shipping requirements at its Arrowsmith North, Arrowsmith Central and Muchea silica sand projects with a view to maximising efficiency and minimising costs. Consequently, the company intends to finalise bankable feasibility studies for all three projects in the September 2019 quarter.
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