Writers : Mallakpaur.M.A
Refference : Geosciences Scientific Quarterly Journal,No.:5,P.:74

Abstract :

Orpiment, Realgar and Antimony deposits in Iran are scattered in Valilu, Siahrud in east Azarbaijan, Shurab, Kuh-e-sorkh, Neginan in Khorassan province, other areas in central Iran, Zarshuran, Aghdarreh, Arabshah, Dash Kassan, Moghanlu, and others which are located in west Azarbaijan, Hamadan, Kurdistan and Zanjan provinces respectively and are all related to magmatism and volcanism of Tertiary age.
Since ancient times, these deposits were actively or semi-active for Arsenic, or Antimony.
Gold as an associated mineral was not considered seriously, and if the name of gold was mentioned it was related to placer or alluvial deposits, particularly, in connection with Zarshuran.
Recent studies in Zarshuran indicated that gold is accompained with other minerals and thus more attention should be focussed on this mineral. The deposits with such paragenesis is called the refractory type and are distributed in various parts of the world.
Due to technological difficulties for beneficiation of such deposits, pr.duction and extraction of gold was limited to placer or oxidized cap.
Presence of Arsenic, Pyrite, Antimony, Lead and Arsenopyrite were the deletrious impurities which caused the working of such deposits to be abandoned.
Technologies advancement during seventies and eighties on this type of ore deposits, created the necessary ground for recommencement of these mines.
Engagement on gold exploration projects, necessitated the compilation of the latest informations on the
so - called refractory gold and their processing techniques. Based on their mineralogy, and some other factors, these types of ores are generally processed by three methods, namely, Roasting, Pressure oxidation and Bio-oxidation, which are briefly discussed in this paper.

Subject List : Gold