A Process Mineralogy Based Approach for Arsenic Removal from Copper Concentrate in Cu – Mo Flotation Circuit

Due to anthropogenic activities of arsenic, its contamination has been widely recognized as one of the most consequential environmental pollutants. This study aims to investigate the possible controlling factors in the amount of arsenic in copper concentrate of the Sungun processing plant – located in northwestern Iran. For this purpose, via utilization of process mineralogy approach, an attempt is made to provide a mineralogical-based approach to reduce or remove As from copper concentrate. Chemical analysis of flotation circuit products shows changes of 0.13-1.00% for As in concentrate, and up to 0.003% for tailings. Arsenic is recovered to concentrate in the form of sulfosalt minerals including tennantite and enargite, along with copper sulfides. In order to reduce the arsenic in copper concentrate, flotation tests are performed in Eh values of +300, +200, +100, 0, -100, -200, and -300 mV. Based on the results, a re-flotation step on copper concentrate with a pulp potential range of -300 to +300 mV is conducted as an effective and optimal solution to reduce the amount of As. At a potential of -100 mV, Cu-As minerals (tennantite and enargite) tend to be depressed, and at +300 mV, these minerals tend to float. During the processing circuit, via flotation of particles with a size of -25 μm and adjusting the pulp potential to +300 mV, it is possible to produce two copper concentrates with low arsenic content (< 0.2%) and high arsenic content (> 0.2%). The first concentrate, which is flotation tailings, can be sold in the same way. The second one can be sold after complete removal of arsenic by leaching and then collection of harmful gases.