Gold Refining by Chlorine Ammonia Purification

1. Brief Introduction
This technology is a gold refining process invented by Changchun Gold Research Institute. The gold refining methods for purification currently prevailing home and abroad are mainly as follows: electrowinning, aqua regia method, and liquid chlorine method, among which the electrowinning method is simple in terms of its flowsheet, and less pollution, but requires strict technology conditions, and large amount of gold has to be overstocked, which brings difficulties in cash flow and security work for the gold mine. While aqua regia method has long production cycle and araises serious environment pollution, and due to the nitrate in the process needs to be removed, large amount of liquid has to be treated, which makes its operation complicated and hard to control. And the liquid chlorine method is mainly using chlorine gas as oxidant, by which the oxidization would subject to be imcomplete once less chlorine gas is supplied. While the emitted chlorine gas is harmful to human beings. Anf furthermore, the product quality by either aqua regia method or liquid chlorine method is not stable.

Chlorine ammonia purifying method provides a new way of simple procee flowshweet, low operation cost, short cycle and less pollution. This method employs sodium chlorate and potassium hypermanganate as oxidant to replace conventional aqua regia or liquid chlorine; at the same time, it uses special purifying techniques and chemical angents in order to control impurities such as iron, copper and silver in the materials, so as to guarantee the product quality of purification. The flowsheet is: impurities removal -- gold solvation -- impurity removal -- reduction.

2.Main Techno-economical Indices
The purified product can be up to class 1 of the national gold standard; the operation cost of purification for different materials is 0.1~0.3 yuan/g. For a plant with annual output of 2 tons of gold, the total capital cost is lower than 1 million yuan.

3. Application Prospects
This technology has been applied in Laozuoshan Gold Mine, Dongfengshan Gold Mine, and many other mines and good economic profits have been made. With opening up of the gold market, higher quality gold is required as a circulation product. So, there is an urgent need from the domestic gold producers to solve the technical problem of refining and purifying. This technology provides a new process that is advanced and better fits the Chinese situations.