ABSTRACT

A two-step closed circuit, operated at 90–95ºC, was found suitable for practical iron removal from real sulfuric acid leach liquors, resulting in low losses of nickel and cobalt to the solid phase. In the first step, NH₄OH was used as a reagent to treat iron-rich liquors (1.8 g.L⁻¹ < [Fe]_total <8.7 g.L⁻¹) with an initial pH of 1.6 ± 0.1, and nickel and cobalt concentrations of 1.59 ± 0.05 g.L⁻¹ and 108 ± 6 mg.L⁻¹, respectively. Metal losses are greatly affected by the liquor’s pH, which increased when liquors with respective higher initial [Ni]/[Fe] and [Co]/[Fe] concentration ratios were treated. Losses were mostly associated with adsorption reactions on the surface of the precipitate, identified mainly as jarosite and goethite phases. Iron removal higher than 99% was obtained at pH 2.5–3.3, with metal losses of up to 1.8%. In the second step, milk of lime (1.5 CaO g/100 mL) was used as a reagent. A final solution containing only 2.1 mg.L⁻¹ of iron, with nickel and cobalt losses below 1.6%, was achieved at pH 3.7–3.8; the precipitate was identified as bassanite. The precipitates presented rapid sedimentation and good filterability, which were observed visually. Filtration operation should be carried out at temperatures above 80°C. A brief review of the literature is also presented.

摘要

发现在 90–95ºC 下运行的两步闭合回路适用于实际硫酸浸出液中的除铁，从而降低了镍和钴在固相中的损失。在第一步中，使用 NH ₄ OH 作为试剂来处理^初始pH 值为 1.6 ± 0.1、镍_和钴浓度^为1.59 ± 0.05 gL ^-1和 108 ± 6 mg.L ^-1， 分别。金属损失受液体 pH 值的影响很大，当处理具有各自较高初始 [Ni]/[Fe] 和 [Co]/[Fe] 浓度比的液体时，pH 值会增加。损失主要与沉淀物表面的吸附反应有关，主要是黄钾铁矾和针铁矿相。在 pH 2.5–3.3 时，除铁率高于 99%，金属损失高达 1.8%。在第二步中，使用石灰乳 (1.5 CaO g/100 mL) 作为试剂。最终溶液仅含有 2.1 mg.L ^-1在 pH 值 3.7-3.8 时，铁的镍和钴损失低于 1.6%；沉淀物被鉴定为bassanite。沉淀物呈现快速沉降和良好的过滤性，目视观察。过滤操作应在 80°C 以上的温度下进行。还对文献进行了简要回顾。