Effect of mechanical activation on enhancement of carbothermal reduction of nickel slag
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ORIGINAL PAPER
Effect of mechanical activation on enhancement of carbothermal reduction of nickel slag Xiao‑ming Li1,2 · Hai‑bo Yang1 · Jin‑bang Ruan1 · Yi Li1 · Zhen‑yu Wen1 · Xiang‑dong Xing1,2 Received: 21 December 2019 / Revised: 10 March 2020 / Accepted: 10 March 2020 © China Iron and Steel Research Institute Group 2020
Abstract The effects of mechanical activation on particle size distribution, crystalline phase, morphology, and mechanical energy storage of nickel slag were studied. Then, the direct reduction experiments of mechanically activated nickel slag mixed with reducing agent graphite powder were performed under conditions of 873–1273 K and reduction for 30–70 min. The results show that after 12 h of activation, 90% of the nickel slag has a particle diameter less than 1.05 μm, and the total energy stor‑ age is 1790.4 kJ mol−1. With the extension of the mechanical activation duration, the intensity of the diffraction peaks of the main crystalline phases F e2SiO4 and M g2SiO4 in the nickel slag decreases. Mechanical activation is also an effective means to enhance the reduction of nickel slag. With the extension of the activation time, the reduction effect of the nickel slag and metallization degree increase. After 12 h of mechanical activation, the nickel slag was reduced at 1273 K for 70 min, and the metallization degree of the reduced product could reach 83.12%. Keywords Mechanical activation · Carbothermal reduction · Nickel slag · Particle size distribution · Mechanical energy storage
1 Introduction More than 2 million tons of nickel slag discharged during nickel smelting with sulfide ores are produced every year in China. Nickel slag accumulates in the slag yard year by year, occupying a large amount of land and wasting available * Xiao‑ming Li [email protected] * Xiang‑dong Xing [email protected] Hai‑bo Yang [email protected] Jin‑bang Ruan [email protected] Yi Li [email protected] Zhen‑yu Wen [email protected] 1
School of Metallurgical Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, Shaanxi, China
Shaanxi Engineering Research Center of Metallurgical, Xi’an 710055, Shaanxi, China
2
metal resources [1–3]. Nickel slag is high in iron content, while the utilization of resources has important environmen‑ tal and social benefits. However, iron mainly exists in the form of fayalite, so it is difficult for conventional reduction and recovery. At present, only a small amount of nickel slag is used in ceramic production [2] or cement production [4], because it cannot be mixed in large quantities due to its high con‑ tent of iron. Iron extraction from nickel slag is an important method for improving its utilization. However, this method is not economic as high temperature is needed to smelt nickel slag and extract iron after reduction. The process of iron extraction by direct reduction is low in temperature and energy consumption, but the iron in nickel slag exists in the form of fayalite, thus showing unsatisfying reduction effect. Enhancement of reduction can
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