Effective Utilization of Limonitic Nickel Laterite via Pressurized Densification Process and Its Relevant Mechanism

Abstract

Limonitic laterite contains low iron and nickel grades and much high smelting minerals and loss on ignition (LOI), identified as refractory iron ore for sintering. Thus, sinter pot tests of limonitic laterite via pressurized densification sintering and its intensification mechanism were conducted, and the industrial application prospect was explored. The results indicate that the sintering performance of the limonitic laterite of the new process is significantly improved with the tumble index and productivity increased by 19.2% and 18.6%, respectively, and solid fuel rate lowered by 10.3%. The external pressure field promotes the synchronization of heat front velocity and combustion front velocity for better sintering heat and mass transfer conditions, which also greatly improves the mineral compositions and microstructure of the product sinter. The microstructure is converted from large thin-wall pores into small thin-wall or large thick-wall pores with the sinter porosity decreased by 42.4%. Much close interlocking texture between hercynite and silico-ferrite of calcium and alumina (SFCA) is formed with hercynite grains aggregation and growth, and SFCA amount substantially increased. The better sintering performance will bring about a remarkable economic benefit of 282.78 million RMB/a if the industrial application is implemented. The pressurized densification sintering process is considered as one of the effective technologies for improving limonitic laterite sintering.

Significant influence of self-possessed moisture of limonitic nickel laterite on sintering performance and its action mechanism

“…2). According to previous investigations [9,10,20], the optimum sinter basicity should be maintained at 1.4 by adjusting the ratio of burnt lime whereas the proportions of return fines and ferronickel tailing were kept at 30 and 1.5 mass% on the basis of the total dry mix, respectively. In addition, limonitic nickel laterite samples with different self-possessed moisture (17, 19, 21, 23, 25 and 26 mass%) were prepared by pre-drying.…”

“…Thus, sinter productivity was adopted to evaluate the output of product sinter in this paper. The relevant methods were exactly in accordance with the descriptions of previous studies [9,10,20]. Vertical sintering speed represented the average flame speed of sintering, which was described as the ratio of sinter bed height to sintering time.…”