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Production of zinc powder from Co-Zn plant residue using selective alkaline leaching followed by electrowinning

Kamran Haghighi H., Moradkhani D., Sardari M. H., Sedaghat B.

Physicochemical Problems of Mineral Processing

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2015

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Vol. 51, iss. 2

411--425

EN

Annually, gigagrams of cobalt residues, called hot filter cake (HFC), are produced from the Co neutralization step at Iranian zinc plants. With respect to the composition of HFC )i.e., 15-25% Zn, 0.5–1.5% Co, 3–8% Mn(, it can be used as a secondary source of zinc, cobalt and manganese. In the present study, for the first time, treatment of HFC for separation and recovery of zinc has been studied. The residue was treated by employing selective alkaline leaching, in order to recover the maximum amount of zinc, followed by zinc electrowinning process. As a results, a solution was obtained from alkaline leaching under the optimum condition of 75 °C, sodium hydroxide of 8 M, solid-to-liquid ratio dm3 of 1:10, and stirring speed of 600 rpm, having zinc recovery of 88.5 %. In the following step, the electrowinning process, under the optimum working conditions being current density 350 A/m2 and time 10 hours, was carried out to produce a zinc powder with high purity of 99 percent. Finally, a simple and effective conceptual flow diagram was proposed for the process.

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Recovery of valuable metals from zinc plant residue through separation between manganese and cobalt with n-n reagent

Moradkhani D., Sedaghat B., Khodakarami M., Ataei I.

Physicochemical Problems of Mineral Processing

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2014

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Vol. 50, iss. 2

735--746

EN

Recovery and separation of cobalt and manganese from one of zinc plant residues (ZPR), namely hot filter cake (HFC) using a hydrometallurgical process was studied. The process is carried out in four steps as follows: (1) washing zinc, (2) reductive leaching with hydrogen peroxide, (3) cadmium cementation with zinc powder and (4) separation of cobalt from manganese with beta naphthol. In this research, the separation between manganese and cobalt from the HFC using N-N reagent was investigated. The influence of several parameters on the course of the reaction such as N-N quantity, pH, temperature and reaction time was also examined. The optimum separation conditions were found to be N-N quantity: 8 times of stoichiometric value, time: 30 min, temperature: 25 °C and pH = 1.5. Using the optimized conditions, the cobalt and manganese precipitation was nearly 99% and 0%, respectively. A kinetic study of manganese precipitation through N-N reagent has been carried out to assess the effect of kinetics parameters. The data obtained for the leaching kinetics indicated that the precipitation of manganese is an ash diffusion controlled reaction and the reaction activation energy is equal to 1.4kJ/mol.

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A study on heavy metals mobility from zinc plant residues in Iran

Moradkhani D., Eskandari S., Sedaghat B., Najafabadi M. R.

Physicochemical Problems of Mineral Processing

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2013

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Vol. 49, iss. 2

567--574

EN

The transport of heavy metals from mining disposal site to groundwater and surface water is one of the most serious environmental problems in the world. The transport of heavy metals such as Zn, Cd and Mn from leaching filter cake in RECo, Zanjan, Iran was examined by using column leaching. Parameters studied included: flow rate, pH of input solution and leaching time. In this study, the maximum dissolution percents of Zn, Cd and Mn in input solution pH of 5 were 45.50 %, 53.97% and 19.94%, respectively. To statistically analysis the experimental results, SPSS14 software was employed. The results of SPSS 14 indicated that for the Zn, Cd and Mn dissolution, time and flow rate were found respectively, the effective parameters for the pollution in zinc leach residues.