Phase Equilibria of Ferrous-Calcium Silicate Slags in the Liquid/Spinel/White Metal/Gas System for the Copper Converting
- PDF / 1,521,181 Bytes
- 9 Pages / 593.972 x 792 pts Page_size
- 82 Downloads / 184 Views
I.
INTRODUCTION
IN the pyrometallurgical copper-making process, the converting process is one of the main steps, where matte (CuÆFeÆS) with the target copper content (matte grade, MG), smelted from the copper concentrate in the smelting process, is further oxidized into blister copper. Generally, the converting process in a conventional Peirce-Smith converter (PSC) can be further divided into two stages, slag blowing and copper blowing. In the first stage, the remaining Fe in the matte is oxidized to FetO, and FetO will react with the flux to be present mainly in the liquid phase and spinel solid phase (normally), whilst partial S will be oxidized into SO2 discharged in the off-gas for acid plants. Therefore, after this stage, a white metal phase (impure Cu2S with a low content of Fe) will be in equilibrium with the slag (spinel and liquid) and gas phases. In the second stage, white metal is further oxidized into blister copper with low levels of S and O.[1] Commonly, the slag phase is skimmed in the
YONGQI SUN, MAO CHEN, and BAOJUN ZHAO are with the School of Chemical Engineering, The University of Queensland, Brisbane 4072, Australia. Contact e-mail: [email protected]. ZHIXIANG CUI is with the Dongying Fangyuan Nonferrous Metals, Dongying, 257000, P.R. China. LEONEL CONTRERAS is with the National Copper Corporation of Chile, Huefanos 1270, Santiago, Chile. Manuscript submitted February 5, 2020.
METALLURGICAL AND MATERIALS TRANSACTIONS B
slag blowing stage; this results in a significant equilibrium state during converting, the system equilibria being composed of white metal, slag and gas phases. To date, there are many studies on the equilibrium of the smelting process,[2–4] but this stage of converting, quite essential for the smooth operation of copper making, is rarely studied, which is the motivation for the present study. Currently, the Peirce-Smith batch process (PS process) accounts for around 85 pct of Cu matte converting, and other converting processes have been developed such as flashing converting, Noranda continuous converting, Mitsubishi converting, etc., driven by enriching SO2 in the off-gas and reduction of SO2 pollution, reduction of Cu loss by slag development and so on.[1,5] Use of an enriched blast is preferred because it will increase the oxidation rate of matte and the SO2 concentration in the off-gas, which will reduce the cost of gas handling and acid making. For example, in the recent ALSI (Air Liquide Shrouded Injector) technique,[6] 30 to 60 pct O2 blast was used, which thereby increased the converter productivity and promoted the feed capacity of solid matte. In the present study, the phase equilibria were investigated for the converting process under a high-level P(SO2), 0.4 atm. Regarding the slag systems, iron silicate (IRS) slags are generally used for the PS converting process and calcium ferrite (CF) slags are used for the flash converting process.[1,5–7] Combining the advantages of these two slag systems, the ferrous calcium silicate (FCS) system, a new slag system
suitable for the
Data Loading...
