Magnesium Removal from Concentrated Nickel Solution by Solvent Extraction Using Cyanex 272
Zhu Zhaowu,
Zhang Jian,
Yi Aifei,
Su Hui,
Wang Lina,
Qi Tao
Issue:
Volume 4, Issue 2, June 2019
Pages:
36-43
Received:
4 May 2019
Accepted:
10 June 2019
Published:
25 June 2019
Abstract: The refinery of mixed hydroxide precipitate (MHP) from nickel laterite processing by acidic re-leaching will generate a concentrated nickel solution containing some magnesium difficult to remove. Fluorite precipitation method is often used for nickel purification from magnesium contamination, causing serious risk of environmental pollution. Solvent extraction technology has obvious advantages in metal separation and purification which has been widely used in nickel cobalt industries. Magnesium separation from nickel in a synthetic re-leach solution by solvent extraction using Cyanex 272 (bis (2, 4, 4-trimethylpentyl) phosphinic acid)) and its analogue of P 507 (2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester) was studied. It was found that the separation factor of magnesium over nickel reached higher than 200 at pH 5.5, which is much better than that of P507 with the maximum separation factor of 88 at pH 5.0. The conditions including equilibrium pH, organic concentration and A/O ratio for metal extraction and separation of Mg and Ca from nickel with Cyanex 272 in a concentrated synthetic nickel solution were optimized. A five-stage counter-current batch continuous test was carried out with Cyanex 272 under optimized conditions. More than 99% of the magnesium was removed from the synthetic solution containing 3.4 g/L Mg and 106 g/L Ni using 0.5 M Cyanex 272, leaving only 38 mg/L Mg in the purified nickel solution, which is suitable for the electrowinning.
Abstract: The refinery of mixed hydroxide precipitate (MHP) from nickel laterite processing by acidic re-leaching will generate a concentrated nickel solution containing some magnesium difficult to remove. Fluorite precipitation method is often used for nickel purification from magnesium contamination, causing serious risk of environmental pollution. Solvent...
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Effluents Treatment Generated by Biolixiviation in the Extraction of Precious Metals through Selective Recovery of Iron, Copper and Zinc
Zambrano Johanna,
Zambrano Johnny
Issue:
Volume 4, Issue 2, June 2019
Pages:
44-50
Received:
16 July 2019
Accepted:
12 August 2019
Published:
2 September 2019
Abstract: Bioleaching comprises the use of microorganisms for metal-extraction processes from sulphide ores. During these complex processes, sulphides are oxidized to sulphates with the generation of heat. As a result, gold, silver, and other precious metals are liberated from the sulphide matrix, improving their recovery after further processing. A drawback of bioleaching processes is the generation of significant amounts of acid solutions with high heavy metal concentrations. If untreated, these acid solutions may alter the physical and chemical characteristics of water and its surroundings, with high impact to aquatic ecosystems. High heavy metal concentrations in solution may also result in pollution to living organisms. A feasible method to treat bioleaching-generated solutions is selective precipitation. This investigation presents the conditions for a successful individual recovery of the main base metals contained in a bioleaching solution with high copper, zinc, and iron concentrations by pH-based selective precipitation. Tests were made with standard solutions of known concentrations of copper, iron, lead and zinc and by titration the concentrations were checked; which allowed to validate the volumetric titration method. The selective precipitation of heavy metals was carried out in three phases using real acid main drainage and bioleaching solutions generated at the laboratory. The first phase in a pH range of 2 to 4 to recover iron; the second phase in a pH range of 4 to 6 to recover copper; and the third phase in a pH range of 6 to 10 to recover zinc. The selective precipitation allowed the heavy metals to be completely removed from the solution or to achieve concentrations below the maximum allowable limit to be discharged to a body of water or public sewer. Results portray that the variation of pH is an effective method, easy to use and not expensive, feasible to be used in the purification of waters that have been polluted with heavy metals.
Abstract: Bioleaching comprises the use of microorganisms for metal-extraction processes from sulphide ores. During these complex processes, sulphides are oxidized to sulphates with the generation of heat. As a result, gold, silver, and other precious metals are liberated from the sulphide matrix, improving their recovery after further processing. A drawback...
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