Abstract
Following the growing demand for Ni and Co and the dwindling supplies of sulfide nickel ore, attention has turned toward the more efficient exploitation and utilization of laterite ore. Using ammonium chloride acid solution to leach is an effective method. Our research concerned investigations on the leaching mechanism and leaching kinetics of laterite. XRD was used to demonstrate the leaching mechanism through analysis of the pattern of the leaching residue and raw ore, showing that acid concentration affects the leaching process more significantly than other factors, and that valuable metals are mainly released from goethite and serpentine. The leaching order of these materials are as follows: Goethite > serpentine > magnetite and hematite. The leaching kinetics were analyzed and this leaching process followed a shrinking core model controlled by a combination of interfacial transfer and diffusion across the solid film. Leaching data fitted to the kinetic equation perfectly, and the apparent activation energies for the leaching of nickel, cobalt, and iron were calculated to be 4.01 kJ/mol, 3.43 kJ/mol, and 1.87 kJ/mol, respectively. The Arrhenius constants for Ni, Co, and Fe were 204.38, 16.65, and 7.12 × 10−3, respectively, with reaction orders of Ni (a 1.32, b 0.85, c 1.53), Co (a 1.74, b 1.12, c 1.22), and Fe (a 2.52, b −0.11, c 0.94).
Highlights
Nickel ranks as the fifth most abundant element after Fe, O, Si, and Mg in the Earth’s crust, and nickel usually exists as oxides, sulphides, deep-sea nodules, and silicates [1]
On the basis of previous work, the optimal leaching conditions consisted of a temperature of 90 ◦ C,On ammonium concentration of 3 mol/L, a hydrochloric acid concentration of 2 mol/L, the basis ofchloride previous work, the optimal leaching conditions consisted of a temperature of 90 ammonium chloride of 3 of mol/L, hydrochloric acid experiments concentrationwere of 2based mol/L, a°C, liquid–solid ratio of 6:1, concentration and leaching time
1), the majority of valuable in this laterite ore exists as composites silicate, or oxide in certain kinds of mineralogical metals such in this laterite layered ore exists as compositesand of serpentine
Summary
Nickel ranks as the fifth most abundant element after Fe, O, Si, and Mg in the Earth’s crust, and nickel usually exists as oxides, sulphides, deep-sea nodules, and silicates [1]. Nickel resources with regards to land reserves are 0.47 billion tons and are present in two principal ore deposit types: 60% of sulfide ore and 40% of laterite ore [2]. Due to its special metallurgical advantages, nickel is a very important metal that is widely used in many industries, especially for the preparation of stainless steel and nonferrous alloys helping to increase corrosion resistance and impact strength [3]. Nearly 85% of nickel is consumed by the alloy and stainless steel industry to impart various materials with certain physical and chemical properties [4,5]. The global demand and the price of nickel and cobalt has increased continuously over recent years, and the sulfide ores have gradually been depleted. Attention has been directed to the development of selective leaching from laterite ores [6,7,8]
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