The cyanidation process for the extraction of gold and silver from ore has been employed since 1898 when it was first used in New Zealand and Africa and soon after in the United States. It is a very efficient process capable of extracting gold in amounts of less than one percent of an ounce from a ton of rock with over 90% efficiency.
Because of the environmental risks, a cyanide management plan is of critical importance to a mining operation. The lack of such a plan, in some cases, has contributed to adverse environmental incidents involving cyanide. The United Nations Environment Programme (UNEP) is developing an international code for the management of cyanide. Implementation and adherence to this code, augmented by experienced scientific and engineering judgment, will help reduce both the number and severity of environmental incidents involving cyanide.
The "Cyanide Management in Mining" courses attempt to provide the user with the necessary background for development of a cyanide management plan that meets the unique requirements of each operating mine. The full complement of courses in the series includes:
- Chemistry of Free and Complexed Cyanide
- Analysis of Cyanides
- Geochemical Properties and Environmental Fate of Cyanide
- Toxicity and Environmental Properties of Cyanide
- Water Management and Discharge Strategies
- Treatment Technologies for Cyanide and Related Compounds
"Chemistry of Free and Complexed Cyanide" is the first in the series of six courses. The chemistry of cyanide solutions is unique, which is responsible for its ability to dissolve gold and silver. Although cyanide is highly selective with respect to combining with gold and silver, in solution it nonetheless forms complexes with other metals, such as mercury, zinc, copper, iron and nickel. It is the formation of these other metal complexes that not only partially accounts for the consumption of cyanide in gold extraction circuits but also generates solutions that can be difficult to treat and analyze.
This course comprises six viewing sessions, each of 30 - 60 minutes duration, plus supporting figures, tables and references, and an interactive review that confirms achievement of the learning objectives.