Co-extraction Of Nickel Research Articles

Cobalt and Nickel Separation in Nitric Acid Solution by Solvent Extraction Using Cyanex 272 and Versatic 10

Recent trend in extraction of nickel and cobalt from laterite ore through hydrometallurgical route is by using leaching agents that can be effectively regenerated, such as hydrochloric and nitric acid. Despite success stories of nickel laterite leaching in nitric acid, investigations on separation of nickel and cobalt from pregnant leach solution in this leaching media are still poorly reported. Nickel and cobalt are mostly recovered in the forms of intermediate products such as mixed hydroxide precipitate (MHP) and mixed sulphide precipitate (MSP). In this paper, separations of cobalt and nickel in nitrate solution and in pregnant leach solution of nickel laterite ore from Indonesia are discussed. Series of solvent extraction tests using Cyanex 272 and a combination of Versatic 10 and Cyanex 272 were performed under variations of equilibrium pH, extractant concentration, temperature and volume ratio of organic to aqueous phase (O/A ratio). The investigation results demonstrate that Cyanex 272 can be effectively used to separate cobalt and nickel in a solution with low nitrate concentration at the absences of Fe and Mg. The increase of equilibrium pH, extractant concentration, O/A ratio and temperature tends to enhance cobalt extraction and co-extraction of nickel. The best condition for separation of Co and Ni was obtained at equilibrium pH of 5, Cyanex 272 concentration 20% (v/v), temperature 25oC and O/A ratio 1/1. Separation of Co-Ni and Mg from pregnant leach solution can be well performed by 2 stage-SX using Versatic 10 followed by Cyanex 272 and selective stripping of loaded organic from the second stage of the extraction by using 1 molar sulfuric acid.

Selective recovery and separation of nickel and vanadium in sulfate media using mixtures of D2EHPA and Cyanex 272

In this research, selective recovery and separation of nickel and vanadium in sulfate media was investigated by solvent extraction using D2EHPA, Cyanex 272, and their mixtures in various proportions. For this purpose, synthetic sulfate solutions of nickel and vanadium were prepared in 2g/L of each metal. After dilution of the organic solvents in kerosene with the ratio of 1–4, experiments were carried out in the pH range of 1.0–7.0 in steps of 0.5 at ambient temperature. Solvent extraction of nickel and vanadium by sole D2EHPA was performed and the extraction percentages were determined to be 90% and 80% for nickel and vanadium, respectively. However, the co-extraction of nickel and vanadium by D2EHPA can be increased with increasing equilibrium pH and temperature. It was shown that using sole D2EHPA, pH50 (the pH at 50% metal extraction) values for nickel and vanadium were 3.5 and 2, respectively; which is not appropriate for the efficient simultaneous separation of nickel and vanadium. Adding Cyanex 272 to D2EHPA in the organic phase, leads to a right shifting of extraction isotherm of nickel and a slight left shifting of the extraction isotherm of vanadium; thus, improves the separation of nickel over vanadium. To optimize the recovery and separation process of nickel and vanadium from the sulfate leach liquor, the influence of different D2EHPA to Cyanex 272 ratios and various temperatures (25, 35, 45, and 55°C) were studied. As a result, optimum separation of vanadium over nickel was achieved with a Cyanex 272 to D2EHPA ratio of 0.35M: 0.25M. Based on the optimum results, pH50 values for nickel and vanadium were shifted from 3.5 to 4.75 and from 2 to 1.75, respectively.

Transfer of cobalt and nickel from sulphate solutions to spent electrolyte through solvent extraction and stripping

We report in this paper studies carried out on the separation and recovery of cobalt and nickel from sulphate solutions through solvent extraction using acid form of PC 88A and D2EHPA diluted in kerosene and stripping of metals from loaded organic phase with synthetic spent electrolyte solutions to generate respective pregnant electrolyte solutions. The typical composition of sulphate solution used for the present study contains Co: 1.91 g/L and Ni: 14.83 g/L. Variation of aqueous phase equilibrium pH in the range from about 3.1 to 6.5 using 0.15, 0.2 and 0.25 M PC 88A indicated increase of cobalt extraction and reaches maximum (∼92–95%) around 5.5 pH with co-extraction of nickel from 0.1 to 5.7%. Comparison of cobalt extraction behavior with the three extractant concentrations showed 0.2 M PC 88A as the best with highest separation factor of about 730 and about 3% co-extraction of nickel only. Using 0.2 M extractant concentration, almost quantitative extraction of cobalt in two counter-current (CC) stages at an aqueous to organic (A:O) phase ratio of 1.5:1 and stripping of metal from loaded organic (LO) in two CC stages at A/O ratio of 1.7 with synthetic spent electrolyte (SE) solution was achieved, generating a pregnant electrolyte solution of pH around 3 suitable for electrowinning. Similar optimum conditions for the treatment of cobalt raffinate to recover nickel using 0.7 M D2EHPA (pH 6.6, unit phase ratio, two stages) and stripping of metal from LO (O/A: 1.7, two stages) with synthetic nickel SE solution were established. Finally, complete process flowsheet for the separation and recovery of cobalt and nickel is demonstrated.

溶媒抽出法による使用済み無電解ニッケルめっき浴からの金属成分の分離

With increasing importance of the electroless nickel plating technology in many fields such as electronic and automobile industries, the treatment of the spent baths is becoming a serious problem. Although the spent baths are currently treated by the conventional precipitation method, a method without sludge generation is desired. This work aims at establishing a recycling process of nickel from the spent baths. Solvent extraction of nickel, iron, and zinc in two types of spent baths (A and B) has been investigated using 2-hydroxy-5-nonylacetophenone oxime (LIX84I) and the acidic organophosphorus compounds such as bis (2-ethylhexyl)phosphoric acid (D2EHPA), 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC88A) and bis (2, 4, 4-trimethylpentyl) phosphinic acid (Cyanex272) as the extractants. Spent bath A is weakly acidic (pH 4.8) and contains 70 g m-3 of zinc as an impurity, and spent bath B is very weakly acidic (pH 6.0) and contains boron. The following results have been obtained: (i) Nickel in spent bath A can be extracted with LIX84I at the pH larger than 6 with high efficiency leaving most of zinc and iron in the aqueous phase. Also, nickel in spent bath B can be efficiently extracted without adjusting pH. (ii) According to the McCabe-Thiele analysis, the concentrated nickel sulfate solution (> 100 kg-Ni m-3) with low sulfuric acid content is obtained by the countercurrent two stage stripping from the Ni-bearing LIX84I using the mixed solution of 0.9 kmol m-3 NiSO4 and 1 kmol m-3 H2SO4 as the stripping reagent. (iii) Iron and zinc in spent bath A can be selectively extracted with the acidic organophosphorus compounds. PC88A and Cyanex272 are more advantageous than D2EHPA because, in the former extractants, the coextraction of nickel is lower and the stripping of iron and zinc is easier. Based on these results, the flowsheets for recovering nickel from the spent baths are proposed.

Separation and recovery of cobalt and nickel from sulfate solutions of Indian Ocean nodules using Cyanex 272

A process for the separation and recovery of cobalt and nickel was optimized for a sulfate leach solution of Indian Ocean sea nodules containing 80 g/m3 cobalt and 730 g/m3 nickel using the sodium salt of Cyanex 272 as the extractant. Extraction of both cobalt and nickel increased with an increase in equilibrium pH and extractant concentration. The extracted species with respect to cobalt appears to be CoA2·3HA. More than 99.6% extraction of cobalt was achieved using 0.04M solvent in a three-stage counter current simulation at the A:O phase ratio of 3:2. The co-extraction of nickel was about 0.6% only. Two-stage countercurrent stripping of cobalt from the loaded organic at an A: O ratio of 1:7 resulted in a pregnant electrolyte enriched by 0.8 kg/m3, thus enabling a ten times overall enrichment of cobalt. From the cobalt-free raffinate, nickel extraction was carried out using 0.25M solvent in two countercurrent stages, and the extraction showed a 99.8% recovery. Stripping of nickel from the loaded solvent was carried out at an equal phase ratio with the advance electrolyte of pH 1.75 in two countercurrent stages. The nickel stripping efficiency was found to be 98.8%. The present studies indicated that complete recovery of cobalt and nickel was possible using nine counter-current stages.

Application of LIX 84 for Separation of Copper, Nickel and Cobalt in Ammoniacal Leaching of Ocean Nodules

The ammoniacal leaching is apparently considered an attractive approach to process polymetallic sea nodules wherein copper , nickel and cobalt are solubilised forming the ammine complexes . To separate these metals, LIX 84, an oxime extractint , was tried from the synthetic solutions . The loading capacity of this solvent for individual metal and ammonia extraction was determined and compared with that of LIX 64N. Preferential extraction of copper over nickel from a mixed aqueous solution was observed . The kinetic studies for the extraction of metals were undertaken to arrive at the retention time appropriate for this operation . Before metal stripping, the mode of ammonia scrubbing from the organic was worked out using acid or a comhination of ammonia -dilute acid as the reagents . The coextraction of nickel and copper and their selective stripping were considered to explore the possibility of separating Cu, Ni and Co from ammonia- ammonium carbonate medium . The separation of these metals from the ammoniacal leach liquor of sea nodules was also attempted.