Leaching kinetics of digenite concentrate in oxygenated chloride media at ambient pressure
- PDF / 334,793 Bytes
- 9 Pages / 612 x 792 pts (letter) Page_size
- 10 Downloads / 202 Views
1.
INTRODUCTION
Pyrometallurgical processes of smelting and converting account for most of copper production from copper sulfide concentrates. These processes, however, inevitably produce SO2 as gaseous by-product. Since present stringent environmental laws do not permit discharge of this gas to the atmosphere, sulfur is captured from the SO2 laden gas streams for manufacture of sulfuric acid. However, efficient sulfur recovery is attained only from the gases produced in the smelting step, while in the batch converting step, completely capturing the gaseous SO2 remains a problem. This situation has led to a renewed interest in hydrometallurgical acid leaching alternatives for processing copper concentrates. Among the alternatives, cupric chloride leaching of sulfides looks promising, because it leads to relatively fast leaching rates at ambient pressure and yields sulfur in the nonpolluting elemental form. Additional advantages are elimination of the dissolution of pyrite, simple techniques for the removal of the dissolved iron, and ease of lixiviant regeneration. Cupric chloride based processes are especially appropriate for leaching concentrates of nonferrous copper minerals such as chalcocite, digenite, or covellite, because in these cases, the leaching solutions will contain little dissolved iron. From the various investigations that have dealt with the cupric chloride leaching of copper sulfides, especially chalcopyrite,[1–5] various processes have been proposed for treating copper concentrates.[6–9] In those investigations, the leaching has generally been carried out at atmospheric pressure using different concentrations of cupric chloride, hydrochloric acid, and sodium chloride under an inert atmosphere. Furthermore, these investigations were oriented to obtain a final leaching solution with most of the copper in the
cuprous oxidation state from which the copper could be electrowon with high energy efficiency. However, for high copper extraction, it was necessary to have a high cupric to cuprous ratio throughout the leaching process. Consequently, countercurrent leaching systems were proposed to obtain high copper extraction.[4,6,7] In one process, an oxidizing pressure leach was used as a final step to complete the dissolution of the concentrate.[9] Habashi and Toor[10] studied the pressure leaching of chalcopyrite in chloride media. They reported that the system HCl-O2 was more effective to dissolve chalcopyrite than the H2SO4-O2 system. They attributed this result to the formation of elemental chlorine in the HCl system. Kunda et al.[11] studied the leaching of copper concentrates in aqueous chloride system at elevated temperatures and oxygen overpressure. They found that chalcopyrite could be oxidized with various chloride salts to form soluble copper chloride or insoluble copper oxychloride salts depending upon the pH of the system. On the other hand, the dissolution of copper sulfides in cupric chloride-oxygen has been investigated very little. Mukherjee et al.[12] studied the leaching of nickel cop
Data Loading...
