Chlorine distillation method is mainly used to treat refractory gold ore. Refractory gold ore refers to those ore has leaching rate less than 80% by standard cyanide leaching even for 20-30 hours. The reason why it is difficult to leach includes:

1.    Packed by other sulfide ore silicate salt minerals, it is difficult to liberate gold from those minerals even by fine grinding, thus avoid the contact with cyanide solution;

2.    Heavy consumption of cyanide and oxide by other associated minerals like arsenopyrite, pyrrhotite, copper pyrite and galena, etc.

3.    Passivation. Such passive film is generated on the surface of gold as sulfide precipitate, peroxide, or dissoluble cyanide, etc.

4.    Pregrobbing effects because of the co-existence of carbonaceous substance and clay,

5.    Difficult-to-melt auriferous minerals in the form of telluride and aurostibite, etc.

Standard pre-treatment to refractory gold ore for better recovery rate includes roasting, pressure oxidation, bio-oxidation, chemical oxidation, etc. However, Metalcess adopts high temperature chloridizing roasting process. The process makes Gold and other precious metals to be converted to chlorate, and then volatilized into vapor. By cooling the vapor to obtain the precious metals chlorate and then to produce high purity metals.

Raw material:

Carbonaceous Gold deposit/ acid leaching residue/Au packaged in pyrite/Arsenopyrite and gangue/Au ≥6 g/t, Ag≥ 30 g/t

Characteristics

1.    Wide adaptability to the tailing, difficult-to-extract ore, low extracting rate ore.

2.    Au/Ag recovery rate＞85%.

3.    During high temperature calcining, CN- decomposes completely.

4.    Low heavy metals containing in tailings, the remains solidified in the slag.

5.    Short process, low investment, high ROI.

6.    Environmental friendly solution.