Prevent Silver Jarosite Formation
Pressure oxidation of refractory (arseno)pyrites results in residues from which nearly all the gold can be recovered. This is not the case for silver. Under prevailing autoclave conditions, which favour hydrolysis and precipitation of ferric iron, the silver becomes associated with jarositic species, limiting its subsequent cyanidation to less than 10 %. Effective enhancement of […]
Pyrite Oxidation Kinetics
The oxidation kinetics of pyrite and refractory gold concentrates in acidified ferrous sulfate solutions in the presence of oxygen-sulfur dioxide gas mixtures has been studied. The effect of temperature, pulp density and gas composition were determined. The optimum oxidation rate was obtained at 80°C and 2 percent sulfur dioxide in the gas mixture. The oxidation […]
Eudialyte Magnetic Separation Recovery
The most common zirconium bearing minerals are zircon, the zirconium silicate ZrSiO4, typically produced from heavy mineral sands in Australia and India, and baddeleyite, the zircon dioxide ZrO2, produced for example at Phalaborwa. A much less common zirconium mineral is eudialyte, a trigonal calcium-zirconium silicate occurring in silica-undersaturated nepheline syenite complexes, such as the Lovozero […]
Dry Grinding Example
The claims which supply oxide and refractory ore feed to the Cortez milling facility are located in both Lander and Eureka Counties. These include the Cortez and Horse Canyon deposits all operated by C.G.M. Joint Venture. Other deposits outside the C.G.M. claim area include; Fire Creek, Buckhorn, Gold Bar and Tonkin Springs. These deposits all […]
Oxide Sulfide Copper Ores Leaching
The results of column leaching tests on 3 different mixed oxide/sulfide ores from a Chilean deposit are presented. The 3 samples contained different ratios of oxide copper minerals to chalcocite and chalcopyrite. The results of the column leach tests are interpreted in light of the shrinking core model for coarse particle leaching. The copper recovery […]
Rhenium Extraction by Leaching in Ammonium Iodide Iodine
Pure rhenium is a refractory metal with a very high melting point of 3180°C. Extraction of rhenium from molybdenite concentrates and other primary sources has been studied for many years. Hydrometallurgical methods using Br2, HNO3, Ca(OH)2, NaOH or Na2CO3 have been investigated. Recently, a new process using halogen salts and ammonium as well as oxygen […]
How Freezing Affects Rock Breakage
Critical size material is defined as ore that is too small to be effective grinding media and too large to be ground. This data showed that both specific energy consumption and critical size production increased during the winter months. The increased energy consumption was in part a result of an increase in the viscosity of […]
Electrowinning of Gold and Silver from Copper Bearing Cyanide
One stage of the cyanide leach process to extract submicron Au particles from disseminated Au ores frequently uses electrolysis. Metals are electrowon from a solution containing Ag, Au, and Cu as cyanide complexes. The electrolyte commonly has Ag and Au concentrations in the 10 to 50 µg/mL range, while Cu, depending on the ore, may […]
How to Recover Hematite and Chromite Magnetic Methods
Wet magnetic separation methods for recovering hematite and chromite fines and ultrafines are investigated in this paper. These methods include wet high intensity and high gradient magnetic separations, carrier or “piggy-back” magnetic method, magnetic field-induced aggregation and magnetic seeding. This investigation indicates that wet magnetic separation is more efficient for fines and ultrafines whereas other […]
Bioleaching Cadmium Sulfide
The applicability of electrochemical techniques in the elucidation of intermediate reactions in the bacterial oxidation of cadmium sulfide minerals has been demonstrated. Furthermore, it was found that the bio-oxidation process was solid-state diffusion controlled. Greenockite (CdS) and hawleyite (CdS) are the most important cadmium minerals, which occur as minor constituents in ores of zinc, lead […]