A Study Of Separation Methods Of Shell And Core Of Roasted Double-Layered Pellet Of As And S Bearing Gold Concentrates

The double-layered pellet (DLP) roasting is one of the effective methods of pretreatment to high-sulfur and high-arsenic concentrate. In this dissertation, the separation of roasted DLP’s shell and core is studied.A series of methods for the separation process are put forward. They have primarily involved Autogenous Grinding, Semi-Autogenous Grinding, Drop Impact and Water Quenching. The impact forces and friction are used to separate the shell and core of roasted DLPs effectively in the former three methods and the thermal stress is used in the last one. The separation rate of Autogenous Grinding is38.94%while Drop Impact84.79%and Water Quenching75.32%.The effect of Semi-Autogenous Grinding is undesirable and the core of DLP is easy to be broke under this approach.Results show that the curing reactions of S and As mainly react in the inner region of DLP’s shell. This region is more compact and mechanically stronger so that the shell and core of roasted DLP can’t be separated effectively. In order to improve the separation process, an innovative isolation layer manufacture technology is proposed. Sodium percarbonate is used to prepare isolation layer. The optimum conditions of preparation DLPs with isolation layer were determined as core particle size8-10mm, Na2CO3dosage5%, the volume of added water in isolation layer5%and coating time2min, mass ratio of DLP’s shell to core1.0, the volume of added water in DLP’s shell30%and coating time12min. When the DLPs with isolation layer roasted at the condition of roasting temperature600℃, roasting time3h, the removal rate of sulfur and arsenic were98.72%and97.54%, and the solidifying rate of arsenic and sulfur both reached over99%. The separation rate of roasted DLP’s shell and core can reach to100%when the roasted DLPs are oscillated for2min after water quenching. Another option for the100%separation rate is to drop the roasted DLPs from1.5m three times.