Grinding Mill Liner & Ball Corrosion Rate
Several wear mechanisms act upon the grinding media, including corrosion, abrasion, and impact. The interactions between these wear mechanisms are poorly understood, and much disagreement exists in the technical literature. To determine the extent to which corrosion contributes to total wear in industrial grinding mills, the Bureau of Mines entered into cooperative agreements with two […]
Grinding Cement Clinkers
Most Cement Clinkers grinding experiments were carried out in a 29.2 cm diameter laboratory ball mill which had a built-in wavy liner. The ball charge consisted of 1.27, 1.90 and 2.54 cm steel balls mixed in equal proportion by number. The ball load corresponded to 40% filling of the struck volume of the mill (denoted […]
Pyrite Oxidation Kinetics – How Fast does Pyrite Oxidize
Pyrite oxidation has been studied extensively, in the past, because of its importance in sulfide mineral separations by flotation, in the generation of acid in mine waters and in leaching of pyrite. The oxidation of pyrite also plays key role in supergene alteration of ore deposits, the formation of acid sulfate soils, etc. Pyrite oxidation […]
Bioleaching Preg Robbing Gold Ore
Refractory precious metal ores in which gold is encapsulated within iron sulfide minerals can be effectively treated by other leaching bacteria in addition to T. ferrooxidans. These include both facultative and obligate thermophiles. Use of thermophilic bacteria for microbial pretreatment of precious metal ores can offer economic advantages over common bioleaching processes in terms of […]
Borate Leaching – In Situ Recovery of Boric Acid
Figure 3 shows a flowsheet of the patented process which involves injection of acid into the deposit, recovery of boric acid-rich solution from production wells and crystallization of boric acid by solar evaporation. The preferred acid in the Duval process is hydrochloric rather than sulfuric acid. The higher initial cost of hydrochloric acid as compared […]
Bacteria Leaching of Gold Encapsulated in Pyrite
It is known that many of the gold and silver deposits are often associated with sulfide minerals, specially pyrite. Some of the precious metals in such ores are often found as very finely disseminated particles inside the sulfide crystals. The encapsulation of the precious metals particles in this manner makes their extraction very difficult, as […]
Determine Mineral Liberation using Breakage Rate
It is quite clear from the data shown in the previous section that parameters for a liberation model can be experimentally determined using image analysis techniques, and that these parameters can be used to successfully simulate the liberation process. However, the process of experimentally determining these model parameters is tedious. It could be simplified by […]
Heap Leaching Practices
Gold Fields’ Mesquite mine, located in southeastern California, heap leaches low grade gold ore at an annual rate of 2.7 Mt (3 million st). Ore is crushed in a two stage open circuit and belt agglomerated prior to loading on the leach pads. Since initial heap construction in October of 1985, a number of operating […]
Modelling and Control of Ball Mill Grinding
Dynamic experiments were performed in a continuous open-circuit 40×40 cm ball mill using a pseudo-random binary sequence of the feed rate and measuring the variations of the discharge particle-size distribution. The impulse response is calculated by a cross- correlation technique. Then a model involving a discrete transfer function and a time-series stochastic equation is calibrated […]
Column Flotation of Copper
A practical application of recent design concepts makes it possible to design a column cell to fit a specific set of conditions. The design and operating parameters of a column cell installation that replaced a conventional two stage copper flotation cleaning circuit at MAGMA COPPER COMPANY, SAN MANUEL, ARIZONA using these design concepts is described. […]