The main obstacle in directly reducing zinc sulfide concentrate in a commercial vertical retort is the difficulty to produce strong briquettes. The authors have successfully applied a new method to the preparation of strong briquettes which have satisfactory strength even after almost all the zinc sulfide in the concentrate has been reduced to zinc vapor. The method consists of mixing zinc sulfide concentrate with pulverized coal and calcium oxide, preheating and briquetting the mixture into a cylindrical briquette of 1.3cm in diameter, and then coking the briquette. Effects of mixing ratio, preheating temperature and time, particle sizes of concentrate, coal and calcium oxide on the strength of the briquette have been axamined. Sinze almost no sulfur has been observe to come out of the briquettes and also since they have considerably low specific resistance of 5.1Ω·cm, it has been suggested that the briquettes may be fed not only into a vertical retort but also into an electrothermic furnace without additional coke.

Kinetic studies of the electric arc furnace (EAF) dust reduction process have been carried out under non-isothermal temperature condition. EAF dust pellets were made with carbon as the reducing agent and dolomite as the binder. A Thermo-Gravimetric Analyzer (TGA) was used to determine the mass loss of pellets, which were heated at an average rate of 40K/min up to 1500℃. The reduction degree was calculated by consideration of the pellet mass loss, evaporation of moisture, dust, zinc and lead at high temperature. The reduction process of EAF dust was divided into three steps related to the change in temperature and time. The non-isothermal reduction kinetics equations were set up to describe every step. The kinetics parameters such as apparent activation energies and frequency factors were established at the same time. It was found that the first step is chemically controlled, the second step is diffusion-controlled and the third step is strongly dependent on the initial content of carbon in the pellet. CrO can be reduced only in the last step by high temperature and high initial carbon content.

By newly-developed computer model[1, 2] of the distribution behaviors of minor elements As, Sb, Bi and accessory elements Pb, Zn in copper flash smelting, copper flash smelting process of Guixi Smelter was simulated. Results showed that the predictions by the computer model were in agreement with the known commercial data from Guixi Smelter. Using Nagamorips physical suspension index equation[3], the apparent percentages of Cu and S in the slag were calculated, and the main form of mechanically entrained copper particles in the slag was determined to be sulfide. Furthermore, the effects of smelting temperature upon the fractional pressures, activity coefficients of As, Sb, Bi, Pb, Zn, etc. and their distributions in matte, slag and gaseous phase were analyzed. According to the simulations, when smelting temperature rises, the volatilizations of As, Sb, Bi, Pb and Zn in gaseous phase increase, while their distributions in matte decrease. The increase of smelting temperature is helpful to improve the total elimination rate of above-mentioned elements in gaseous and slag phases.