Smelting Reduction Process with a Coke Packed Bed for Steelmaking Dust Recycling.

Abstract

A new smelting reduction process with a coke packed bed has been developed for iron, chromium, and nickel recovery from BOF dust, and for simultaneous recovery of zinc and iron from the electric arc furnace dust. The process is characterized by direct use of fine raw materials without agglomeration, recovery of almost the whole amount of zinc and lead, and no emission of secondary waste, compared with the conventional recovery methods.The commercial plant for BOF dust recycling has been operating stably with a metal production capacity of 200 tons per day. The blast condition is controlled so that the temperature at the lower tuyere level becomes higher than 1 550°C, which is the condition required for the smelting reduction of chromium and iron oxides.The validity of the process idea for EAF dust recycling was confirmed and the key technologies were established through the pilot plant tests with a scale of 10 tons per day. It was found that zinc oxide was almost completely reduced and vaporized at the thermal state of the furnace, T melt м1 550°C, which allowed chromium and iron to be reduced. The control of the temperature and CO 2 /CO ratio of the top gas was important for the prevention of zinc adhesion on the wall of the furnace top.

Continuous Fuming of Zinc-Bearing Residues: Part II. The Submerged-Plasma Zinc-Fuming Process

“…[7,8,9] In this technology, EAF dust or oxidic waste in powder form along with coal powder is injected at the tuyere level of a low-shaft furnace together with a small quantity of preheated gas. [7,8,9] The shaft of the furnace is filled with coke, and in front of each tuyere in the lower part of the coke column, a cavity is formed in which the reaction between the injected oxide and reducing agent (carbon, CO) occurs. Liquid metal and slag phases are formed.…”

Vapor Pressure Measurement of Zinc Oxychloride

“…Pressure of ZnCl 2 The transport of ZnCl 2 was measured as a function of the flow rate of carrier gas and oxygen partial pressure at 823 K and 873 K. Figure 2 shows the weight loss of ZnCl 2 as a function of the flow rate of carrier gas with p O 2 ϭ3.04ϫ10 4 Pa at 873 K. The weight losses of ZnCl 2 in Fig. 2 were to be independent of the flow rate of carrier gas over the range of 50 to 80 cm 3 /min.…”

“…[4][5][6][7][8] Hara et al 4) reported that zinc oxide in EAF dust was almost reduced and vaporized as metallic zinc in pilot plant tests for EAF dust recycling. They concluded that zinc and iron could be separately recovered.…”

Vapor Pressure Measurements for the FeCl<SUB>2</SUB>-ZnCl<SUB>2</SUB> System by the Transpiration Method

“…In pyrometallurgical process halogens react with alkali or heavy metal and evaporate easily as halides and/or oxyhalide compounds. Hara et al 4) reported that zinc oxide in Electric arc furnace (EAF) dust was almost reduced and vaporized as metallic zinc in pilot plant tests for EAF dust recycling. They showed that zinc and iron could be separately recovered.…”

“…Various methods have been proposed for the treatment of these dusts, [1][2][3][4] both pyrometallurgical and hydrometallurgical, but the majority is disposed as of landfill. Hydrometallurgical treatment is difficult for these dusts due to the presence of insoluble chloride compounds such as ZnOÁZnCl 2 ÁnH 2 O which prevent from electrowinning.…”