INDONESIA Metallurgical testing of limonite and saprolite ores from the island of Halmahera shows promising results, says Toronto-based WEDA BAY MINERALS. The new tests are part of the bankable feasibility study being prepared for a potential nickel producer. The work developed a combined pressure acid leach (PAL), atmospheric leach (ATL) and saprolite neutralization (SN) process flowsheet. Creation of a bulk laterite treatment plant would lower the capital and operating costs of the project, previously estimated to be about US$902 million.
Results of the tests pointed toward five key results. Feed thickening increases solids density at the head of the PAL circuit. Recovery in excess of 95% nickel and cobalt was achieved from the limonite feed in the PAL circuit. Two hours’ retention time of saprolite feed in the ATL circuit recovered over 96% of the nickel. The SN circuit can achieve recoveries of over 80% after four hours of reaction. Use of a counter-current decantation (CCD) circuit is feasible for the combined leach product.
The Halmahera project has measured and indicated resources of 133 million tonnes grading 1.37% Ni and 0.11% Co. The inferred resource adds another 82 million tonnes at 1.33% Ni and 0.12% Co to the total. Cut-off grades of 1.0% Ni and 0.1% Co were used.
Technical information, maps and photos of Weda Bay’s project are posted at www.wedabay.com.