NUNAVUT – Starfield Resources of Toronto reports that Phase 2 hydrometallurgical tests on ore from its Ferguson Lake copper-nickel-cobalt project within the Hearne Domain of the Churchill Province were successful. The tests were conducted by SGS Canada in Lakefield, ON.
Phase 2 tests included an extended oxidation run using actual feed during early January 2011. Oxidation is the first step after the massive sulphides are dissolved in the primary leach. The primary leach is used to dissolve the iron sulphide in the Ferguson Lake material, leaving the base metals in the solids to be dissolved in the secondary leach to be separated later. The purpose of oxidation and hydrolysis is to convert the dissolved iron to solid iron oxide and to regenerate the acid used in the primary leach. Preliminary results showed that the target single-pass oxidation level of 80% was achieved at about 18 hours run time and was exceeded after that.
The next most important part of the process is hydrolysis, where the leach solution is treated to recover hydrochloric acid. Test work on the hydrolysis portion of the process was successfully completed in Phase 1 using synthetic feed. Acid recovered contained from 20% to 26% hydrochloric acid, the strength at which it is used in the primary leach. During Phase 2 testing, the oxidation and hydrolysis sections will be re-run together using actual solution from primary leach testing.
SGS also completed a series of flotation tests for Phase 2. These tests showed it is possible to easily reject 75% to 80% of gangue, while recovering 99% of base metals and 97% of precious metals. Leaving more gangue at the mine site reduces the amount of non-sulphide material transported to the process plant, which in turn reduces costs by requiring less pumping power, smaller pipe lines and smaller tankage at the process plant. All of this results in higher metal value per ton processed.
The flotation test work produced approximately 200 kg of bulk concentrate, some of which will be used for primary leach testing in the Phase 2 work, to produce the feed needed for testing the oxidation and hydrolysis sections. The next step in this phase of testing will use the primary leach solution in a continuous loop from oxidation to hydrolysis to verify that actual feed works as well as synthetic feed. Some of the resulting oxidized solution and some of the filtrate from hydrolysis will be used to test the performance of the secondary leach in which the base metals are dissolved.
Detailed information about the Ferguson Lake project are available at www.StarfieldRes.com.