Refining Gold: Remove Zinc by Distillation
It seems desirable to remove zinc more completely than can be done by acid-treatment, and also to obtain it in a form at once available for precipitation again. I feel safe in saying that from 40 to 50 per cent, of the zinc originally used for precipitation could be thus recovered. Philip Argall says, in […]
Refining Zinc Precipitates: Cyanide Leaching of Gold & Silver Extraction
Attempts to discover, for the cyanide process, a better precipitant than zinc have been unsuccessful. Hydrogen sulphide, sulphurous acid, ferrous sulphate, etc., precipitate gold and silver from cyanide solutions either not all or incompletely. Aluminum has been tried, but it costs too much, and cannot be used in solutions containing lime. Charcoal has been used […]
Assaying Zinc Box Residues in Cyanide Leach Process
Several methods, both wet and dry, for the assay of zinc-box residues from the cyanide process, have been described in recent years, and each of them has been claimed to be superior to all others. A paper, entitled “Assay of Zinc Precipitates,” was published in the School of Mines Quarterly to the purport that the […]
Plant for Zinc Precipitation of Gold
Cyanide Precipitation Equipment is designed to meet the demands of cyanide plants for a low cost, efficient method of precipitating gold and silver from a cyanide solution. Metallurgical results obtained with this equipment have proved highly satisfactory and usually compare favorably with results obtained with more complicated processes although the machines are simple and inexpensive. […]
Merrill-Crowe Zinc Precipitation Startup and Shutdown
The Operation of a Merrill-Crowe Zinc Precipitation circuit requires for Preparation for its Startup that the following items be checked before the equipment in the Merrill-Crowe Zinc Precipitation Circuit is started. Note the levels in the pregnant solution, clarified solution and barren solution tanks. The pregnant and barren solution tanks should be approximately half full. If the pregnant solution tank is full […]
Merrill-Crowe Zinc Precipitation Circuit Operation
In the Merrill-Crowe Zinc Precipitation, the pregnant solution tank collects the gold and silver bearing solution recovered from other circuits of the plant: thickener overflow; primary and secondary filtration? and the Argentite circuits. Normally these solutions contain very little solids content (15-100 ppm), however, even this small amount of solids is sufficient to inhibit efficient […]
Startup and Shutdown Procedure -Merrill Crowe
In Preparation for Startup, the following items must be checked before the equipment in the filtration circuit is started. Check that the filters, repulpers, filtrate pumps, vacuum pumps, flotation blower, and transfer pumps are ready to run. Check that the cooling water compressant system is functional. The selected cooling water filter must be clean, and reclaim water must […]
Merrill Crowe Slurry Filtration Circuit Post-Agitated Leach
The object of the post agitated leach drum filtration circuit is to recover as much of the dissolved gold and silver as possible. The efficiency of recovery can be increased significantly by utilizing two successive stages of filtration such as the two stage system applied in this plant. Recovery of the precious metals is also improved […]
Zinc Cyanide & Silver Gold Precipitation
In cyanidation, zinc (the Merrill-Crowe Process) is practically the universal precipitant for precious metals dissolved in cyanide solutions although for specific reasons aluminium and charcoal have been used. During the reactions involved in precipitation, the greater part of the zinc dissolves in the cyanide solution and forms various cyanogen complexes such as sodium or calcium […]