Direct Cyanidation of the Original Re-Washing

Fractions of the original sample of these second washings of metals were submitted to the process of cyanidation by continuous agitation in rollers at different times of contact (24, 28, and 72 hours), with the purpose of evaluating the efficiency in the dissolution of the silver (main metallic cost) and the gold (secondary metallic value).

Direct Cyanidation of the Re-Washing

• Weight of the sample = 0.300 Kg.
• Solid-liquid relation = 1:3
• Percentage of cyanide = 0.13%
• pH = 10.5
• time of contact: 24, 48 and 72 hours

Direct Cyanidation of Net – 325 Fraction
Fractions of the sample were sieved in damp by net 325 for its future cyanidation, in the following sample we will see the results:

NET 325 WEAKENING

Product Thickness ( +325) 

Weight 70.0% 
Laws Oz/TC Ag 8.18 Au 0.019
Distribution  Ag% 34.25  Au% 32.52

Product Fine (-325) 
Weight 30.0% 
Laws Oz/TC Ag 36.64 Au 0.092
Distribution  Ag% 65.75  Au% 67.48

Product c.c. 
Weight 100.0% 
Laws Oz/TC Ag 16.71 Au 0.041
Distribution  Ag% 100.00  Au% 100.00

It can be noted that in the fine fraction ( - 325) the sieving represents an average of the 30% of the original weight, a very significant concentration of values of 65.75% Ag and 67.48% Au has been performed. It is to be expected that the silver must be in small particles and, as a consequence, must answer better to the cyanidation.

The reports of chemical analysis by mercury in the thick fraction gives a result of 1907 ppm, which represents the 97.0% of the mercury contained in the original sample.