Continuous Elution for Extraction of Gold from Carbon
The continuous elution process is a continuous counter-current system operating in a pressure vessel at elevated pressure and temperature in which both carbon and the eluate are simultaneously moving through each other in opposite directions. During this process the carbon particles enter the top of the vessel loaded with gold and exit barren through the […]
Hydrochloric Acid Leaching of Merrill Crowe Precipitate
Significant copper levels were anticipated in the precipitate due to cyanide soluble species in the ore. Original design called for a hydrochloric acid leach of precipitates to remove excess zinc and copper prior to fusion. It was thought that the use of hydrochloric acid would result in low silver losses because of the low solubility […]
Flash Flotation of Gold
The Outokumpu flash flotation concept as an approach for precious metals recovery. Concerns were: Could a concentrate be recovered from coarse, high solids cyclone unflow. Would the proposed flash flotation machine operate on 2 continuous basis or would machine be down frequently because of plugging. Freeport was well aware of the mechanical problems with unit […]
Grinding Circuit Expert System Control
The clear abstraction of application specific knowledge from computer instructions is fundamental to all expert systems. This property greatly simplifies the encoding of knowledge and allows expert systems to describe their line of reasoning. Provided first that a human expert can articulate his skills, the expert system can mimic his decision making. The label “expert […]
Prevent Permeability Loss in Heap Leaching
The Bureau of Mines Twin Cities Research Center conducts research to assist in solving problems that occur during solution mining of metals. Solution mining of uranium involves injecting a carbonate-bicarbonate (basic) or sulfate (acidic) leach solution through injection wells into an ore body where the lixiviant dissolves the uranium from the ore. Uranium bearing lixiviant […]
Ore Grade Control
Initial ore grade control was based on blast hole samples collected in two stages by an “automatic” sample collection device (sometimes called a rocket sampler). A sample was collected for the top 3 m (10 ft) in a holes and then the bag was changed so that a sample was collected for the lower 3 […]
Mining Truck Dispatching Method
The main purpose of truck dispatching systems is to increase equipment productivity. Since productivity is measured in tonnage or volume over time, productivity increases are made by decreasing truck and shovel cycle time. This decrease can be translated into more production with the existing operating equipment or constant production with a smaller equipment fleet. Concurrent […]
Heap Leach Solution Management
Column testwork on run of pad ore composites has shown that varying the solution application rate from .005 gpm/ft² to .001 gpm/ft² has no effect on the overall silver or gold extraction after a short period of time of 2-3 weeks. The pregnant solution grade is inversely proportional to application rate leading to like extraction […]
Determining Corrosion Rates in Grinding Environments
Researchers at the Bureau of Mines, U.S. Department of the Interior, developed and tested equipment to measure corrosion rates on a commercial-scale mill. Bench-scale experiments were also designed for duplicating ore grinding conditions closely enough that realistic rate determinations can be made in laboratory tests. Rates measured in a laboratory system compared favorably with those […]
Tungsten & Gold Recovery Scheelite Ores
Investigations were conducted by the U.S. Bureau of Mines to develop flowsheets for the recovery of tungsten and gold from four Alaskan scheelite-bearing ores. Basic gravity concentration and cyanide leach tests were performed on all samples. About 46 pct of the tungsten and 30 pct of the gold from one sample were recovered in a […]