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The effect of sulfur in rotary kiln fuels on nickel laterite calcination

University of British Columbia

Rotary Kiln - Electric Furnace (RKEF) process is the most commonly used pyrometallurgical technique for processing nickel laterite ores and is mainly suited for saprolite deposits. Sulfur is one of the most harmful elements in crude ferronickel obtained via the RKEF process and adversely affects the mechanical properties of the final product. Typically, laterite ores contain insubstantial sulfur content; hence, it is hypothesized that most of the sulfur in crude ferronickel originates from the coal added as the fuel and the reductant during calcination in the rotary kiln. This study investigates the role of sulfur content of rotary kiln fuels on the composition of the calcine. The calcination-partial reduction experiments were conducted in a furnace at 900 °C for a 2-hour residence time. Various reducing gas mixtures representing combustion product of rotary kiln fuels (i.e., coal) were contacted with the ore. The sulfur content of the resulting calcines were measured by ICP-AES analysis. At constant PCO, the sulfur content of the calcine increases linearly with an increase in PSO₂ in the input gas mixtures. Similarly, at fixed PSO₂, the percentage of sulfur in the calcine and sulfur deportation increase with PCO. However, an exceptional case is observed at PSO₂ = 0 atm, where the sulfur content and sulfur deportation slightly decrease by increasing PCO in the input gas. The sulfur content and the percentage of sulfur deportation drop at a lower input flow rate of the reducing gas mixtures. Lastly, the sum of the metallized and sulfurized iron/nickel was found to increase with an increase in PSO₂.

Text

2020-01-13

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/73313

Materials Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/