Converting Minerals to Metals - Mining and the Environment: From Ore to Metal - page 265

FIGURE 6.10
Process Involved in Gold Extraction
and Benefi ciation

Extraction
(Open Pit or Underground)

CYANIDATION VAT LEACHING

Roasting, Autoclaving
or Bio-oxidation Used for
Ores Where Gold Occurs
within Pyrite Grains

Crushing

Roasting, Autoclaving
and Biooxidation

CARBON-IN-PULP CARBON-IN-LEACH

Tank Leaching Using
Cyanide Solution

Concurrent Tank
Leaching Using
Cyanide Solution and
Gold Adsorption on
Activated Carbon

Gold Adsorption on
Activated Carbon

Elution (Stripping Gold
from Activated Carbon)

Zinc Precipitation
may be used for
Ores Containing
High Silver
Concentration

Electrowinning

Zinc Precipitation

Smelting

Refining

applying a sodium cyanide solution to dissolve the gold which is then adsorbed on to car-
bon. Gold is then stripped from the carbon, using sodium hydroxide solution, and recov-
ered by electrowinning, the product of which is smelted to produce doré bars containing
gold and silver metal. A simplified flowchart for the process is provided as Figure 6.10 .
Common steps are as follows.