INDONESIA WEDA BAY MINERALS of Toronto is pleased with results of the metallurgical tests conducted on its laterite ore from the Halmahera nickel/cobalt project in Indonesia. The tests were conducted by LAKEFIELD ORETEST in Perth, Australia. The study was conducted as part of the process to create a combined pressure acid leach/atmospheric leach/saprolite neutralization (PAL/ATL/SN) flowsheet for the ore. The proposed plant will treat the entire laterite profile of limonite and saprolite.
Tests included the use of seawater in the feed preparation plant. It was found that salt water improves the pulp density of limonite feed to the PAL process, compared with using fresh water. Consequently, the thickener area required to achieve a feed density of 37% has been reduced. Test results using seawater yielded high nickel and cobalt recovery, fast leaching rates, and low final acidity in the combined leached pulp. The results are summarized in a news release posted at www.WedaBay.com. Using seawater also controlled aluminum and ferric iron levels in the leach liquor, thus eliminating the need for downstream treatment.
The Halmahera deposit contains total measured, indicated and inferred resources of 215.1 million tonnes at 1.35% Ni and 0.11% Co. According to a 2002 prefeasibility study, Weda Bay estimates that it will take US$902 million to establish an open pit mine and plant with an annual capacity of 64,700 tonnes of nickel and 5,300 tonnes of cobalt. The average operating cost is estimated to be US$0.78/lb of nickel in a mixed sulphide intermediate product exclusive of cobalt credit.