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2 Physicochemical Problems of Mineral Processing

2 2018

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Simultaneous extraction of vanadium and chromium from vanadium slag using low-pressure liquid phase oxidation method

Xia J.-P., Zheng S.-L., Wang S.-N., Liu B., Zou X.

Physicochemical Problems of Mineral Processing

2018

Vol. 54, iss. 2

609--619

A low-pressure liquid oxidation method was proposed and proven to be effective to extract vanadium and chromium simultaneously from the vanadium slag in concentrated NaOH aqueous solutions. The effect of temperature, NaOH mass concentration, liquid-to-solid mass ratio, stirring speed and pressure on the extraction of vanadium and chromium in NaOH aqueous solutions were systematically investigated. Under the optimal reaction conditions (temperature of 473 K, liquid-to-solid mass ratio of 6:1, stirring speed of 700 rpm, NaOH mass concentration of 50%, pressure of 1 MPa and reaction time of 180 min), the vanadium and chromium recovery reached 95% and 90%, respectively. It was found that the reaction temperature and NaOH concentration were important factors for the extraction of vanadium and chromium. The kinetics of the decomposition of vanadium slag in concentrated NaOH aqueous under low pressure was analyzed using the shrinking core model, and the results indicated that the extraction of vanadium and chromium were both governed by the internal diffusion step, with apparent activation energies calculated to be 26.22 and 32.79 kJ/mol, respectively.

Effect of sodium sulfide waste water recycling on the separation of chalcopyrite and molybdenite

Wu D., Peng H., Abdalla M.

Physicochemical Problems of Mineral Processing

2018

Vol. 54, iss. 3

629--638

The effect of sodium sulfide waste water recycling on the separation of chalcopyrite and molybdenite was investigated in this work. The waste water, which was separated from the slurry after selective flotation, was recycled in the flotation system. This operation significantly improved the subsequent flotation of chalcopyrite and saved the reagent. The results showed that the depression efficiency of sodium sulfide gradually disappeared in the recycling tests due to the consumption. The consumption of sodium sulfide in the separation was not only caused by the adsorption on mineral surfaces but also resulted from the precipitation of metal ions which released from minerals. These effects decreased the solution reducibility and the adsorption of hydrosulfide ions, finally resulting in the less depression for chalcopyrite flotation. After adding a certain amount of sodium sulfide to the recycling, the depression of chalcopyrite performed well and the pulp potential maintained at a relatively lower level. Moreover, the pulp potential was an available parameter to control the flotation separation of chalcopyrite and molybdenite, which made the method easily applied to industry.