Two-wavelength pyrometry study of the combustion of sulfide minerals: Part II. Galena and commercial lead concentrates
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I.
INTRODUCTION
VAPORIZATION reactions are very important in the flash smelting of lead sulfide concentrates due to the volatility of lead species.V~] However, little information is available on the mechanism of combustion of individual particles or on the influence of a combination of minerals in industrial concentrates on their combustion. In part I of this series of articles, t51 the measurement of the temperature of individual particles during combustion, by two-wavelength pyrometry, was presented. Characteristic differences between the combustion of lead and iron sulfide minerals in air were reported. In air, galena particles were found to combust, at a relatively constant temperature of around 1400 to 1700 K, and to produce large quantities of fume reaction product similar to that reported by Happ and Jorgensen.t6] This is thought to be due to the vaporization of PbS, limiting the reaction temperature, followed by its combustion in the gas phase to P b O / e b S O 4. In con-
N.E. TUFFREY, formerly Graduate Student, Centre for Metallurgical Process Engineering, University of British Columbia, is Senior Research Metallurgist, Sherritt Inc., Fort Saskatchewan, AB, Canada T8L 3W4. G.G. RICHARDS, formerly Associate Professor, Department of Metals and Materials Engineering, University of British Columbia, is Senior Research Scientist, Cominco Research Ltd., Trail, BC, Canada V1R 4S4. J.K. BRIMACOMBE, Alcan Chair in Materials Process Engineering, and Director, Centre for Metallurgical Process Engineering, is with the University of British Columbia, Vancouver, BC, Canada V6T 1Z4. Manuscript submitted April 13, 1994. METALLURGICAL AND MATERIALS TRANSACTIONS B
trast, iron sulfides combust at temperatures of 2200 to 2750 K in air and exhibit large energy increases, most likely due to the inflation of cenospheres, t5,7-9] On the basis of characteristic pulses determined for iron and lead sulfide combustion given in part I,[51 the present article investigates the influence of oxygen concentration and mineral composition on the combustion of lead concentrates. The pyrometry technique, outlined in the previous article, was adopted to measure the temperature of individual particles during reaction. This, in conjunction with chemical and morphological examination of quenched reaction products, allowed reaction phenomena to be identified and provided valuable information on the combustion mechanism of galena and commercial lead concentrates.
II.
EXPERIMENTAL
A. Feed Material
The combustion of galena (Pine Point Northwest Territories, Canada, Cominco Ltd.), Sullivan (Cominco Ltd., Trail, B.C.), and Brtmswick (Brunswick Mining and Smelting, Bathurst, New Brunswick, Canada) commercial lead concentrates was investigated. Screen fractions between +230 (63/xm) and - 120 (125/xm) were used for the combustion experiments. The chemical composition of the - 1 2 0 + 140 (105- to 125-/zm) screen fraction of the different materials is given in Table I. Thus, the amounts of iron, zinc, and sulfur increased (and lead decreased) in th
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