China
Africa
Explore chapters and articles related to this topic
Leaching with Ferric and Cupric Ions
Published in C. K. Gupta, T. K. Mukherjee, Hydrometallurgy in Extraction Processes, 2019
Cubanite (CuFe2S3) is a copper mineral which is occasionally of economic importance, especially in the Sudbury basin of Canada. Dutrizac et al.61 studied the dissolution of synthetic cubanite in the temperature interval 45 to 70°C. The material used in the experiment was a metastable, high temperature form of CuF2S3 which dissolved slowly according to the following equation: () CuFe2S3+3Fe2(SO4)3→CuSO4+8FeSO4+3S0
The Direct Leaching of Nickel Sulfide Flotation Concentrates - A Historic and State-of-the-Art Review Part II: Laboratory Investigations into Pressure Leaching
Published in Mineral Processing and Extractive Metallurgy Review, 2023
Nebeal Faris, Mark I. Pownceby, Warren J. Bruckard, Miao Chen
The U.S. Bureau of Mines investigated the hydrochloric acid-oxygen pressure leaching of a bulk Cu-Ni sulfide concentrate from the Duluth Gabbro (Minnesota) grading 9.3% Cu and 1.6% Ni (Smyres, Lei and Carnahan 1985). Principle sulfide minerals in the concentrate were pyrrhotite, chalcopyrite, cubanite (CuFe2S3) and pentlandite. The leaching experiments were performed in a synthetic chloride solution containing dissolved metals (Cu, Ni, Co, Ca) and sulfate to simulate the recycling of various process streams such as solvent extraction (SX) raffinate to the leaching stage; the HCl required for leaching was added externally. Preliminary experiments (344.7 kPa (gauge) O2 pressure, temperature not specified) found that HCl additions which produced a leach liquor with a terminal pH of 1.7–1.8 were favorable with respect to Cu (94%), Ni and Co extraction (98–99%) with only 10% of the sulfide being oxidized to sulfate and low iron concentrations in the liquor (<0.1 g/L). Insufficient addition of HCl resulted in precipitation of dissolved copper as atacamite [Cu2(OH)3Cl] though the precipitate could be redissolved by adjusting the pH to 1.7–2. The effect of leaching temperature on concentrate dissolution was also evaluated in larger scale leaching experiments. Generally higher temperatures resulted in lower residence times (0.5 h at 120°C vs. 5.5 h at 100°C) and terminal liquor pHs (0.9 at 120°C vs. 1.8 at 100°C). However, the dissolved Fe concentration (2 g/L at 120°C vs. 0.1 g/L at 100°C) and the degree of sulfide oxidation to sulfate also increased at higher temperatures (14 to 15% at 120°C vs. 12% at 100°C); the increase in sulfide oxidation to sulfate however did lower HCl requirements. Higher leaching temperatures improved the settling properties of the slurry with the filtration being twice as fast at 120°C vs. 100°C which was suggested to be due to agglomeration of elemental sulfur during the higher temperature leach. The use of compressed air instead of oxygen was also trialed by Smyres, Lei and Carnahan (1985) where it was found that Cu, Ni and Co extractions were 86%, 99% and 98%, respectively, after leaching at 100°C for 4 h at a pressure of 379.2 kPa and HCl addition of 0.28 g per g of concentrate. Possible improvements to Cu recovery such as higher acid addition or post leach pH adjustment were suggested by the authors. Dissolution of precious metals in all experiments were found to be erratic and not reproducible, typical extractions for Au, Ag, Pd and Pt were 55%, 90%, 45% and 40%, respectively.