Pilot testwork to produce concentrate
Cookes Creek Tungsten
Hazelwood’s focus in Australia is the 100% owned Cookes Creek Tungsten Project in the East Pilbara of Western Australia. Hazelwood has worked towards de-risking this project as a future source of feedstock for its downstream ferrotungsten business in Vietnam.
A pre-feasibility study provided a strong case for the development of the Big Hill Deposit, based on low grade bulk mining and efficient ore sorting and gravity processing techniques to provide clean feedstock for ferrotungsten production.
Note: 0.07% WO3 is the standard for resource estimation in China, which is the world’s largest tungsten producer.
The advanced Mineral Resource has given rise to an Ore Reserve that is predominantly in the Proved Reserve category. Big Hill can be mined to low cut-off grades due to the extra value created beyond the mine gate at Hazelwood’s downstream ferrotungsten plant in Vietnam.
Further revisions to the Mineral Resource and Ore Reserve are planned during the feasibility study, taking into account new drilling results and examining alternate mining scenarios.
Significant volumes of work complied by Hazelwood and independent consultants led to the completion of in integrated prefeasibility study that considers the development of Big Hill as a source of feedstock for the ATC Ferrotungsten Project. Engineering cost estimates were developed to an accuracy limit of +/-20%. A total capital cost of $A111.6 million was estimated (December 2009 costs).
Under the mining and processing schedule for the pre-feasibility study with a plant throughput of 2.3Mtpa of ore, two million metric tonne units of tungsten concentrate would be produced over an operational life of approximately 12 years. Annual production of up to 200,000 metric tonne units (1.6 million kilograms of contained tungsten) would be sufficient to provide up to 2/3rd of the feedstock for ATC Ferrotungsten.
Two processing options were investigated, one with ore-sorting pre-concentration, the other without ore sorting. A total of 35 process flowsheets and general arrangement drawings were derived, with mass and energy balances. The ore sorting option was selected on the basis of overall operational efficiency.
Ore is subject to three stages of crushing and ore sorting via X-ray transmission detection. Ore sorting is a proven technology in use at many operations including operating tungsten mines. The ore sorted product is transferred to a rod mill and reduced to an 80% passing size of 950 microns. Beneficiation takes place on conventional spirals and tables. No flotation is required in this circuit.
Mining by conventional open pit mining methods is proposed. The life of mine strip ratio, based on robust pit optimisation and mine design is only 2.2 waste tonnes : 1 ore tonne. Average mining costs of approximately $3.13 per tonne of material moved were indicated (2010 costs).
Permitting and approvals are planned to be progressed during the definitive feasibility study over the course of 2011. Infrastructure tenure is granted for the project, which is already serviced by gazette roads. All tenure that encloses the proposed operation is live, with a Mining Lease under application. The grant of the Mining Lease is subject to negotiations with a single registered Native Title claimant.
Groundwater exploration during the prefeasibility study identified the majority of the project’s water needs within 5 kilometers radius of the proposed mine. Additional water exploration and test bores are proposed during the definitive feasibility study.
Hazelwood adopted industry best practice in its environmental monitoring by conducting flora and fauna surveys early in the evaluation schedule. Most of the required environmental surveying has been completed and there appear to be few obstacles to the development of the Big Hill Tungsten Deposit. Environmental assessment documents are likely to be lodged towards the end of the definitive feasibility study.
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