Sulfides Formation in Carbothermic Reduction of Saprolitic Nickel Laterite Ore Using Low-Rank Coals and Additives: A Thermodynamic Simulation Analysis

Abstract

In this paper, a systematic thermodynamic analysis of carbothermic reduction of saprolitic nickel laterite ore was carried out. Different carbon sources—such as pure C, sub-bituminous, and lignite—were used for the carbothermic reduction at 1000 °C (1273 K). The effect of the different additives—such as S, FeS, Na2S, Na2SO4, and CaSO4—was also systematically evaluated. The thermodynamic calculations suggested that the use of low rank coals (sub-bituminous and lignite) do not significantly affect the nickel grade and nickel recovery, but affect the total metals recovery. The presence of S in these C-sources promoted the formation of sulfides. At 1000 °C (1273 K), only a small amount of C-sources (C, sub-bituminous, lignite) are needed to significantly metallize the nickel in the laterite, i.e., between 4–6 wt %. The additives S, FeS, Na2S, Na2SO4, and CaSO4 were predicted to promote the formation of liquid sulfides, and at the same time reduce the formation of the (Fe,Ni) alloy, thus reducing the nickel and total metals recovery. Therefore, consideration is needed to balance the two aspects. The calculations predicted that S, Na2SO4, and CaSO4 additions provided an increase in the nickel grade; while FeS and Na2S reduced the nickel grade.

The advances in the recovery process for precious metals from nickel slag, a review

“…In this instance, selective reduction aims to extract the target metal efficiently while either reducing or not reducing any additional metals that might be present in the mixture. Selective reduction is a pyrometallurgical process that uses a temperature of 1000-1200 o C and coal as a reducing agent [16]. The parameters determining the selective reduction process are temperature and reduction time, reducing agents, and added additives [17].…”

Kajian Literatur Parameter Proses Reduksi Selektif Bijih Nikel Laterit

“…Penggunaan batubara (bituminous dan lignite) sebagai reduktor telah banyak dilakukan (Elliot et al, 2017;Elliot et al, 2015;Jiang et al, 2013;Li et al, 2012), dikarenakan ketersediaan yang cukup melimpah dan harganya yang relatif jauh lebih murah. Berdasarkan penelitian yang telah dilakukan oleh Harjanto et al (2019), bahwa penggunaan reduktan batubara lignite (low-rank coal) tidak mempengaruhi kandungan dan perolehan nikel, namun mempengaruhi perolehan logam, dimana perolehan logam pada proses reduksi dengan menggunakan reduktan batubara lignite jauh lebih rendah dibandingkan dengan batubara bituminous. Hal tersebut dikarenakan kandungan karbon dalam batubara lignite yang lebih rendah dibandingkan dengan bituminous.…”

Enhanced Selective Reduction of Laterite for the Highly Efficient Enrichment of Ni and Co by NaFeS2 and Its Recycling

“…Reductive roasting was performed in the solid-state (1000–1200 °C), where fine ferronickel grains were aggregated with the aid of additives such as NaCl, CaSO 4 , Na 2 CO 4 , CaF 2 , S, Na 2 SO 4 , Na 2 S, and Na 2 S 2 O 3 . ,− Its energy consumption could be reduced by 44% compared with the RKEF process, while also achieving adaptability to various laterites. − During roasting, the highly active alkali metal ions reacted with silicate minerals to release nickel and cobalt by destroying their molecular structure . This process avoided the formation of high-melting silicates and reduced the resistance of solid reaction. , With the presence of sulfide, a partial metal oxide was sulfureted to form the low melting point liquid phase, promoting the migration of metal particles and restraining the reduction of iron and increasing the nickel and cobalt grades of the final product. , The sulfur in the liquid phase also reduced its surface tension for the transformation of metal ions. , Suitable additives were strategic for the solid reductive roasting of laterite.…”