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Selective flotation of witherite from calcite using potassium chromate as a depressant

Qiu Yangshuai, Zhang Lingyan, Jiao Xuan, Guan Junfang, Li Ye, Qian Yupeng

Physicochemical Problems of Mineral Processing

2019

Vol. 55, iss. 2

565--574

Witherite has been widely used as an industrial and environmental source of barium, with calcite being the primary associated carbonate mineral. However, few studies have been conducted to effectively concentrate witherite from barium ores. In this work, with the treatment of potassium chromate (K2CrO4) and sodium oleate (NaOL), witherite was selectively separated from calcite through selective flotation at different pH conditions. In addition, contact angle, Zeta potential, adsorption and X-ray photoelectron spectroscopy measurements were performed to characterize the separation mechanisms. The results demonstrated that NaOL had a strong collecting ability for both witherite and calcite; nevertheless, witherite could be effectively selected from calcite with the highest recovery at pH 9 in the presence of K2CrO4. From the XPS measurements, NaOL and K2CrO4 were found to be primarily attached to the surfaces of witherite and calcite through chemisorption. The presence of K2CrO4 on the surface of calcite adversely influenced the NaOL adsorption, which could make the flotation separation efficient and successful.

Production of potassium chromate from a low-grade Egyptian chromite ore and potassium carbonate

El-Roudi A. M., Othman A. G., Alla E. M. A., Zhran R. M.

Polish Journal of Applied Chemistry

2006

Vol. 50, nr 3-4

65-73

The production of K2CrO4 from low-grade chromiteore, its preoxidiscd form and locally available materials has been studied. The roasting of chrome ore-K2CO3 mixture with a mole ratio of 1:2.75 for 300 min.at 1000°C was performed to prepare K2CrO4 with a recovery of 93%. Increased recovery was obtained when chromitc was preoxidised and roasted up to 975°C. The oxidation rate of roasting with SiO2 mole ratio of 2.9 was increased when adding a clay raw material. The reaction mechanism was presented.