Cyanide Regeneration Processes and Methods
Cyanide regeneration offers a practical means of overcoming the otherwise heavy cyanide consumption frequently encountered in the treatment of gold and, especially, silver ores, where cyanicides (cyanide consuming minerals) are present. Miscellaneous processes used for the extraction of gold and silver values by hydrometallurgical means are also discussed in this chapter. These include the carbon-cyanidation, […]
Carbon Cyanidation
Countercurrent carbon cyanidation with simultaneous dissolution of gold by cyanide and its adsorption by carbon offers several advantages over other carbon cyanidation processes as: the rate of dissolving the gold is faster, higher grade gold-bearing carbon is obtained, less carbon per ton of ore treated is required, separate dissolving and absorbing units are not needed, adsorption […]
Aerating or Oxygenating Cyanide Solutions
A process for aerating or oxygenating cyanide solutions was announced by T. K. Prentice in the Jour. C.M. and M.S.S.A., February, 1934 (see Fig. 56). It immediately attracted attention, and the article was reprinted in part by United States and Australian technical journals. The process received practical plant trials at the Nourse mine on the […]
Effect of Impurities on Cyanide Leach Solution
That cyanide solutions in works practice do not remain pure in a chemical sense is to be expected, having in view their contact during treatment with the many contaminants found in gold or silver ore amenable to cyanidation. Impurities cause a chemical cyanide loss and at times detrimentally affect the extraction of the valuable metals […]
Effect of Altitude & Pressure on Gold Leaching Kinetics
Altitude-pressure and Standard Saturation Curves: Chart A (Fig. 55) is used to determine barometric pressure at various altitudes; Chart B is used to determine standard saturation values for various temperatures and pressures. In Chart A, altitudes, in feet, are plotted on the horizontal axis and pressures, in millimeters, on the vertical axis. To find the pressure […]
Cyanide Gold Dissolution
Manufacturing Cyanide Sodium cyanide is a white, deliquescent, crystalline material easily soluble in water. The basic sources are alkalis or alkaline earths, atmospheric nitrogen, and carbon. In the United States it is derived (1) from sodamide which is produced from sodium and ammonia. The sodamide is heated with charcoal, and the resultant soda cyanamid is […]
Cyanide Solution Control Parameters
In both cyanidation and flotation practice it is necessary to keep a close check on the working solutions, since the concentration of various soluble salts derived from, the ore or supplied as a protective measure to the system is usually critical. Alkalinity Because of the need in most instances for maintaining a definite protective lime […]
Sampling Pregnant Solution
The press-tails solution going to storage discharges into a spill box (A in drawing), thence passing through a bottom pipe into the barren-solution storage tank. The solution will stand in the spill box at a level depending on the volume of flow, i.e., the volume precipitated. On the side of box A is a smaller […]
Amalgamation Process of Gold
The use of direct amalgamation following stamps or primary mills and the use of barrel amalgamation for treating jig and corduroy concentrates. Precipitation of gold and silver on zinc dust or on zinc shavings is fully treated, from the clarification and de-aeration of cyanide solutions to the cleanup and melting of the bullion. The use of […]
Gold Ore Roasting Techniques
In the case of many complex gold and silver ores roasting before cyanidation is essential if satisfactory extraction of the precious metals is to be obtained. In such cases no practical amount of grinding or prolonged contacting of the raw ore with cyanide solution will affect more than a certain low extraction; in other cases, […]