Extraction efficiency of metals from low-nickel matte via NH₄Cl roasting-water leaching process and synthesis of (Ni,Cu,Co)Fe₂O₄ photocatalyst

Abstract

Aiming at high energy consumption and large Co loss in the pyrometallurgy of low-nickel matte, a process of NH₄Cl roasting-water leaching was proposed to co-extract metals, followed by the separation and utilization of metals. The effect of several factors on metal extractions in NH₄Cl roasting process and the optimized process conditions were investigated by orthogonal experiments. The most influencing factors were roasting temperature and NH₄Cl dosage, and the optimized chlorination conditions were as follows: particle size of low-nickel matte <75 µm, roasting temperature of 500 °C, roasting time of 2.5 h, NH₄Cl dosage of 250% and O₂ flow rate of 20 mL/min. By studying the effect of temperature and time on the extraction efficiency of metals, the appropriate leaching conditions were determined as temperature 90 °C and time 2 h. The extraction efficiency of nickel, copper, cobalt and iron can reach 97.6%, 96.2%, 94.5% and 29.2%, respectively. The (Ni, Cu, Co)Fe₂O₄ photocatalyst was synthesized from leaching solution using α-Fe₂O₃ as a carrier to composite with other metals. The optimum conditions were determined as precipitation temperature 25 °C and molar ratio of Ni-Cu-Co to Fe 1:3. The as-prepared catalysts were spherical nanoparticles of approximate 40–60 nm, and the degradation rate of which to methylene blue solution can reach 99.8% within 120 min.

摘要

针对低冰Ni 火法冶炼过程能耗高、Co 损失大的问题,本文提出了NH₄Cl 焙烧-水浸联合提取金属,再分离利用金属的工艺。通过正交试验,研究了NH₄Cl焙烧过程中不同因素对金属提取的影响,并确定了优化的工艺条件。结果表明,焙烧温度和NH₄Cl用量为主要的影响因素,最佳氯化条件为: 低冰镍粒径<75 µm,焙烧温度500 ℃,焙烧时间2.5 h,NH₄Cl用量250%,O 2 流速20 mL/min。通过研究温度和时间对金属浸出的影响,确定了适宜的浸出条件为: 温度90 ℃,时间2 h,这时Ni、Cu、Co和Fe 的浸出率分别达到97.6%、96.2%、94.5% 和29.2%。以浸出液为原料,以α-Fe₂O₃ 为载体与其他金属复合,合成了(Ni,Cu,Co)Fe₂O₄ 光催化剂。最佳制备条件确定为: 沉淀温度25 ℃,Ni-Cu-Co 与Fe 的摩尔比1: 3。制备的催化剂为40~60 nm 的球形纳米颗粒,在120 min 内对亚甲基蓝溶液的降解率可达99.8%。