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Open AccessArticle

Mechanism of Calcium Sulphate on the Aggregation and Growth of Ferronickel Particles in the Self-Reduction of Saprolitic Nickel Laterite Ore

by Guihua Hang 1,2,3, Zhengliang Xue 1,2,3,*, Jinghui Wang 1,2,3 and Yingjiang Wu 1,4
1
State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, China
2
Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081, China
3
Hubei Provincial Engineering Technology Research Center of Metallurgical Secondary Resources, Wuhan 430081, China
4
WISDRI Engineering and Research Incorporation Limited, Wuhan 430223, Hubei, China
*
Author to whom correspondence should be addressed.
Metals 2020, 10(4), 423; https://doi.org/10.3390/met10040423
Received: 7 March 2020 / Revised: 24 March 2020 / Accepted: 24 March 2020 / Published: 25 March 2020
Saprolitic nickel laterite is characterized by relatively low iron and nickel contents. Iron and nickel oxides are reduced to form fine ferronickel particles that disperse and embed in silicates in the reduction process, limiting the application of magnetic separation to extract ferronickel. Additives are applied to promote the aggregation and growth of ferronickel particles, then the large ferronickel particles will be separated by fine grinding and recovered via magnetic separation. Calcium sulphate is considered to be capable of increasing the size of ferronickel particles considerably. Due to the decomposition of calcium sulphate in the reduction process, the mechanism of calcium sulphate on the aggregation and growth of ferronickel particles should be conducted studied in-depth. The current work explores the effects of calcium sulphate, elemental sulphur, and calcium oxide on the formation of ferronickel particles in a saprolitic nickel laterite ore. The results showed that the formation of an Fe-FeS eutectic and the mineral structure transformation contributed by calcium oxide were all conducive to the mass transfer of ferronickel particles in gangue, ferronickel particles aggregated and grew up at the boundary between the hole and the gangue. The self-reduction, fine grinding, and magnetic separation of nickel laterite ore in the presence of three types of additive were examined. Nickel laterite ore with 7.88 wt% coal, 12 wt% calcium sulphate reduced at 1200 °C for 30 min, a ferronickel concentrate of Ni 8.08 wt%, and Fe 79.98 wt% was obtained at a nickel and iron recovery of 92.6% and 79.9%, respectively. View Full-Text
Keywords: nickel laterite ore; calcium sulphate; aggregation and growth; self-reduction; magnetic separation nickel laterite ore; calcium sulphate; aggregation and growth; self-reduction; magnetic separation
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Hang, G.; Xue, Z.; Wang, J.; Wu, Y. Mechanism of Calcium Sulphate on the Aggregation and Growth of Ferronickel Particles in the Self-Reduction of Saprolitic Nickel Laterite Ore. Metals 2020, 10, 423.

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