Search

Most nickel laterite smelting to produce ferronickel is carried out using an AC-arc furnace. Although the DC-arc furnace is advantageous in the smelting of fine ore, it is rarely used for nickel laterite. In this work, the effects of slag basicity and stoichiometry of reductant addition during smelting of low-grade saprolitic nickel ore on nickel content and nickel recovery, yield, and phases of the slag were studied in detail. The smelting process was conducted in a laboratory DC-arc furnace with a a single electrode of 30 cm diameter. A 5 kg of low-grade saprolitic nickel ore (1.92 Ni-12.97 Fe), some coke as reductant, and some limestone as flux were smelted in a DC-arc furnace for about one hour. The pouring temperature of hot metal and slag was 1400-1500°C. The basicity of the quaternary slag of 0.8 and the stoichiometric carbon of 0.8 of the reductant resulted in an optimum smelting process of nickel ore in a DC-arc furnace, producing ferronickel with a Ni content of 14.59% with 92.26% recovery.

Rare-earth metal is one of the critical elements because of its small amount with a lot of demand for this metal in a variety of the latest technologies, which are currently developed fast and intensively. The use of rare-earth metals can contribute to the development of innovations in the production of new materials in various fields, because these metals have strong, hard and heat-resistant properties. Rare-earth metals are found in complex compounds that makes it difficult to separate from ore. Obtaining of the rare-earth metals is realized by recycling the product from a secondary source of magnets containing rare-earth metals, such as NdFeB and SmCo magnets. Hydrometallurgical and pyrometallurgical processes can carry out the process of recovering of the rare-earth metals from secondary materials. There is a new research using bacteria as a rare-earth metal extractor to minimize environmental impact. Oxalic acid and other organic acids have potential in the recovery of rare-earth metals. As alternative, the rare-earth-free materials as candidates for permanent magnets are also mentioned. [ABSTRACT FROM AUTHOR]

Laterite nickel ore is a mineral rock, which contains iron–nickel oxide compounds. One processing technology proposed to treat the ore is the Caron process. In general, the Caron process combines pyrometallurgical and hydrometallurgical stages. In the pyrometallurgical step, the ore mixed with reductant is heated up to 1800 °C in a rotary kiln-electric furnace to transform iron–nickel oxide into iron–nickel alloy. In the hydrometallurgical stage, nickel has to be dissolved selectively using ammonia solution (alkaline). The further process is aimed to separate and purify the nickel in ammonia solution using solvent extraction and precipitation. The disadvantages of the pyrometallurgical stage in the Caron process include high-energy consumption, low economic value, and technical problems such as partially melted material, which hinders the further process. While in the hydrometallurgical stage, the extensive use of ammonia causes an environmental impact. Selective reduction is proposed to solve problems in the pyrometallurgical stage. Selective reduction is a process favouring the formation of iron oxide to obtain high nickel content in an intermediate product with less energy consumption. An additive is added to the ore to reduce selectively the nickel and decrease the reaction temperature. To solve the environmental impact of ammonia, a novel and safer chemical is proposed as a substitute — the monosodium glutamate (MSG). Selective reduction combined with alkaline leaching using MSG is proposed as an alternative to the Caron method. Precipitation is employed further to purify the nickel that results in nickel nanoparticles with 90–95 wt.% purity. [ABSTRACT FROM AUTHOR]