Heap Leaching Gold & Silver Ores
An investigation of a particle agglomeration technique as a means of increasing the percolation rate of leaching solutions through heaps of clayey or finely crushed, low-grade, gold and silver ores. Bench-scale and pilot-scale experiments conducted on different ores indicated that the percolation rate of cyanide leaching solution was enhanced markedly by mixing the ore with […]
Gold Heap Leaching Practices
Heap leach gold recovery techniques are employed at Ortiz. Caustic cyanide solutions are sprayed onto crushed rock piles, dissolving the metallic gold from within the rocks and carrying it out as a ‘pregnant’ gold containing solution. The solution is then passed over carbon particles which the gold preferentially precipitates upon. The gold loaded carbon is […]
Copper Cementation for Small Scale Operations
We studied the precipitation of copper from dilute acidic sulfate solutions using shredded automobile scrap in a rotary drum. The tests established that the scrap in the rotary drum precipitated copper faster and more completely than shredded, detinned, tinplate scrap in a launder, with comparable iron consumption. Although power is required to rotate the drum, […]
Sample Preparation for Gold & Silver Assay
Sample Preparation: Aqua regia with, occasionally, the addition of hydrofluoric acid is the most used lixiviant, and is applicable to most ore types. Other combinations of acids as well as cyanides are also used, and pre-roasting is sometimes applied. Digestion time and amount of reagent vary, quite naturally, with the amount of acid consuming materials […]
Merrill Crowe vs Carbon
Several economic comparisons have been made between carbon systems and Merrill-Crowe systems. One of these, a systematic comparison completed by DeMent and King (1982) is summarized below. Five separate conventional mills involving both Merrill-Crowe and the CIP processes were compared from an economic viewpoint. The gold concentration on the feed leach liquor ranged from 0.428 […]
Foam for Dust Control
The Code of Federal Regulations (Title 30, Chapter 1, Part 57, Section 57.5-1) requires that metal and nonmetal mines shall maintain a time weighted average (TWA) for total and respirable airborne dust concentrations below that established by the American Conference of Governmental Industrial Hygienists in 1973. This TWA for total dust concentrations must be under […]
Carnallite & Sylvinite Ore – Potash Flotation
The mission of the Bureau of Mines minerals research program is to help improve minerals processing technology so that the Nation’s mineral needs can be fulfilled in a manner that reduces waste and ensures that minerals and metals are processed, used, and recycled at acceptable economic, social, and environmental costs. In accordance with this mission, […]
Fire Resistance of Conveyor Belts
Conveyor belt fires can present a serious hazard in the confined environment of an underground coal mine. To minimize this hazard, Federal regulations were enacted following the Federal Coal Mine Health and Safety Act of 1969 to require the use of acceptable fire-resistant conveyor belts and suitable belt slippage-sequence switches, fire warning devices, and fire […]
Elutriation Bowl: Falcon & Knelson
Elutriation Another enhanced gravity device was patented in 1935 by A. N. MacNicol (Figure 4). It is also a truncated cone but ribs divide the length into a series of slots. A water jacket and connecting holes are used to inject water and elutriate a bed of material in each. Some companies have produced this […]
Uranium Acid Leaching
Mechanism of Uranium Leaching: Uranium leaching with sulphuric acid is a complex process governed by chemical dissolution, and the oxidation of uranium. It is controlled by surface etching, diffusion, and mass transfer within the ore. The physical parameters are in turn controlled by the physical properties of ore, and the ore size. The leaching process may […]