Producing Calcium Cyanide At A Mine Site Using Easily Transportable Starting Materials

Abstract

The present invention is a method by which the mine can obtain a supply of calcium cyanide for use in its leaching operations. Specifically, one preferred method within the scope of the invention involves producing hydrogen cyanide directly at a mine site using formamide as a starting material. Alternative methods of producing hydrogen cyanide at the mine site using easily transportable starting materials, such as methanol and urea, are disclosed. The hydrogen cyanide is neutralized at the mine site with slaked lime (Ca(OH)₂) to form the calcium cyanide.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the benefit of U.S. Provisional Application No. 60 / 661,182, filed Mar. 11, 2005.BACKGROUND OF THE INVENTION[0002]The present invention relates to producing cyanide for mining applications. More specifically, the present invention relates to producing cyanide for mining applications at the mining site using starting materials that are readily transportable.[0003]Aqueous solutions of cyanide anions (or “cyanide”) are used extensively in the mining industry as a mechanism for extracting precious metals, such as gold and silver, from the earth. Generally, these aqueous cyanide solutions contain sodium cyanide, potassium cyanide, or cyanide salts of other alkali metals. Although miners have tried to find other means of winning the gold from the ores, cyanide extraction continues to be the only cost-effective mining technique. Accordingly, it is believed that cyanide will remain the material of choice for precious metal m...

AI Technical Summary

Benefits of technology

[0016]This invention provides a method by which a supply of cyanide is produced directly at a precious metal mine. This supply of cyanide may then be used by the mine in its leaching operations to extract the precious metal from the earth. The ability to produce cyanide at the mine site may provide the mine with long-term stabil

Problems solved by technology

During the process, some cyanide oxidizes and some is lost for further use.

There is some production of hydrogen cyanide from other processes, but this is limited and is generally not a source for NaCN.

Despite the market for cyanide, there are growing concerns in the mining industry that supplies of cyanide will not be available at a commercially viable price in the future.

It is anticipated that older facilities and technology currently used to manufacture hydrogen cyanide will become obsolete, thereby reducing the amount of HCN that is currently being produced and sold.

Thus, the overall cost of cyanide is expected to increase in the future.

In fact, in the public's view, the use of cyanide is considered a threat to the environment and a possible tool for the use of terrorists.

It is becoming more difficult to ship cyanide internationally.

Many international mining operations are concerned that future restrictions/regulations may restr

Images