Pressure cyanide leaching for precious metals recovery

Abstract

Research Summary Aqueous ProcessingA novel method demonstrates that the oxidation and dissolution of gold and silver in alkaline cyanide solution can be conducted simultaneously in the same autoclave in less than 90 minutes with a recovery that exceeds 96%. Because mild operating conditions of 80°C and 0.6 MPa oxygen pressure are used in this process, low cost materials of construction can be utilized for the autoclave. José R. Parga, Jesús L. Valenzuela, and Francisco Cepeda T. are with the Instituto Tehnologico de Saltillo in Saltillo, Mexico. Dr. Parga can be reached at jrparga@its.mx.Figure 9. The results of continuous plant operation.

Detoxification of cyanide using titanium dioxide and hydrocyclone sparger with chlorine dioxide

“…Accordingly, the sodium cyanide concentration (molecular weight of NaCN = 49) should be equal to 4 x 0.26 x 10 -3 x 49 = 0.05 g L -1 or approximately 0.01%. This was confirmed in practice at room temperature by a very dilute solution of NaCN of 0.01-0.5% for ores, and for concentrates rich in gold and silver of 0.5 -5% (Parga, 2007). Aat the end of this leaching process, free cyanide enriched solutions, easily dissociable cyanide compounds, and metallic cyanide complexes are generated (Botz, 1998).…”

Metallurgical Amenability Testing of Bir-Tawilah Gold Deposit in Central Arabian Gold Region, Saudi Arabia

“…Similarly, the tails from Falcon were also combined to form a composite tails for cyanidation (48 hours with 1 g/L NaCN). Each test was carried out with and without lead nitrate, added at approximately 100 g/t, for four experiments [17].…”

New Technology for Recovery of Gold and Silver by Pressure Cyanidation Leaching and Electrocoagulation

“…Table 5. Advantages and disadvantages of methods for recovery of gold and silver (Emamjomeh et al 2004;Mollah et al, 2009;Parga et al, 2007).…”

“…This electrochemical method of contaminant removal requires smaller quantities of salt addition to increase the conductivity of the solution (typically, an aqueous electrolye), and the maintenance and operation of the EC cells are relatively simple. Electrocoagulation processes offer significant potential for removing ionic species from solution, particularly heavy metals (Mollah et al, 2004;Parga et al, 2007). Operating conditions are highly dependent on the chemical composition and properties of the aqueous medium, specifically, conductivity and pH.…”