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Separation of nickel and zinc ions in a synthetic acidic solution by solvent extraction using D2EHPA and Cyanex 272

Gharabaghi M., Irannajad M., Azadmehr A. R.

Physicochemical Problems of Mineral Processing

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2013

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Vol. 49, iss. 1

233--242

EN

Solvent extraction was used to recover nickel and zinc from synthetic acidic solution. Many leaching solution and waste waters contain both zinc and nickel at the same time. Bis (2,4,4trimethylpentyl) phosphinic acid (Cyanex 272) and Di(2-ethylhexyl) phosphoric acid (D2EHPA) were used to separate nickel and zinc. In the D2EHPA system, at equilibrium pH of 2, zinc extraction was more than 98% whereas nickel extraction was only 0.36%. The extraction of metals was found to increase with an increase of pH of the aqueous phase. At equilibrium pH 3.5, zinc extraction was completed and higher than 99% zinc was extracted using Cyanex 272. The maximum nickel extractions using D2EHPA and Cyanex 272 were achieved at equilibrium pH 4.5 and 7.5, respectively. Both extractants showed the relatively good separation levels between nickel and zinc. D2EHPA and Cyanex 272 isotherms for single metal solutions showed that the extraction order was Zn2+>Ni2+. ΔpH1/2 value showed that the separation of nickel and zinc using Cyanex 272 was simpler than D2EHPA system. The stripping study was performed using sulphuric acid and it was shown that above 98% zinc and nickel could be extracted. These results demonstrated separation of zinc and nickel from sulphate solutions to be favorable.

2

Leaching of zinc from low grade oxide ore using organic acid

Irannajad M., Meshkini M., Azadmehr A. R.

Physicochemical Problems of Mineral Processing

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2013

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Vol. 49, iss. 2

547--555

EN

The leaching of low grade zinc oxide mining tailings by organic acid as a leaching agent was investigated. Zinc was extracted successfully from sample by citric acid leaching. The effects of solid-to- liquid ratio, acid concentration, reaction time, temperature and ore particle size on the leaching efficiency were studied. The results obtained showed that particle sizes and reaction time had not any significant effect on the leaching recovery of zinc from smithsonite in the sizes range of 40-350 μm. Under conditions: temperature of 80ºC, reaction time of 60 min, citric acid concentration of 0.5 mol/L, and solid to liquid ratio of 1:10, 82% of zinc could be recovered.

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Process optimization of nickel extraction from hazardous waste

Gharabaghi M., Irannajad M., Azadmehr A. R., Majid E.

Archives of Environmental Protection

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2012

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Vol. 38, no. 3

29-40

EN

Zinc plant residue is a hazardous waste which contains high quantity of nickel and other valuable metals. Process parameters such as reaction time, acid concentration, solid-liquid ratio, particle size, stirring speed and temperature for nickel extraction from this waste were optimized using factorial design. Main effects and their interactions were obtained by the analysis of variance ANOVA. Empirical regression model was obtained and used to predict nickel extraction with satisfactory results and to describe the relationship between the predicted results and the experiment results. The important parameters for maximizing nickel extraction were identifi ed to be a leaching time solid-liquid ratio and acid concentration. It was found that above 90% of nickel could be extracted in optimum conditions

4

Acidic leaching of cadmium from zinc plant residue

Gharabaghi M., Irannajad M., Azadmehr A. R.

Physicochemical Problems of Mineral Processing

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2011

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Vol. 47

91-104

EN

In the present paper cadmium leaching from zinc plant residue using sulphuric acid was examined. The zinc plant residue is a hazardous waste which is produced in the hydrometallurgical zinc plant and it contains considerable amounts of metals such as zinc, cadmium and nickel. The effects of sulphuric acid and other important factors such as reaction time, solid-to-liquid ratio, particle size, stirring speed and temperature on cadmium recovery were investigated. The concentration of cadmium in solution was observed to increase with the increase of the reaction time, acid concentration, stirring speed and temperature. Decreasing of solid/liquid ratio and particle size were also beneficial for cadmium recovery. The largest cadmium leaching recovery (97%) was obtained after 30 minutes of treatment at 25°C using H2SO4 (8% (v/v)) at solid-to-liquid ratio of 0.10. XRD and SEM analyses of the residues obtained after leaching showed that the cadmium containing phase had been decomposed in the leaching residues. The results indicated that it is possible to use this waste as a secondary resource for cadmium recovery.