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2 Physicochemical Problems of Mineral Processing

2 2020

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Removal of calcium from magnesite flotation concentrate by selective leaching and kinetics analysis

Hu Xiaoxing, Zhu Yangge

Physicochemical Problems of Mineral Processing

2020

Vol. 56, iss. 5

939--948

Dolomite is the main impurity mineral in magnesite ore, affecting the quality of magnesite products. This study proposed a selective leaching process to reduce the calcium content from the magnesite flotation concentrate using hydrochloride acid (HCl). Laboratory scale tests were conducted to explore the influence of operation factors including HCl concentration, leaching temperature and time, stirring speed on the leaching recovery. The results showed that leaching recovery of CaO and MgO increased with increasing HCl concentration, temperature and time. The CaO leaching recovery is always significantly higher than that of MgO, indicating a good selectivity of HCl to leach dolomite from magnesite. The leaching kinetics of both dolomite and magnesite follow the Avrami model and are diffusion controlled, with an activation energy of 43±}1 kJ×mol-1 and 25±}4 kJ×mol-1, respectively.

Effect of grinding media on the flotation of copper-activated marmatite

Long Tao, Chen Yao, Shi Juanjuan, Chen Wei, Zhu Yangge, Zhang Chonghui, Bu Xianzhong

Physicochemical Problems of Mineral Processing

2020

Vol. 56, iss. 2

229--237

How to avoid the shortage of floatability and non-purpose flotation in marmatite flotation is a big problem. This paper innovatively studies how to reduce these two negative phenomena from the perspective of grinding media. The effects of steel and stainless-steel balls on the flotation performance of copper-activated marmatite were investigated mainly through flotation tests, redox potential measurements, ion concentration tests, and XPS and FT-IR spectrum studies. The flotation results showed that the floatability of copper-activated marmatite remarkably decreased by using the steel ball in the grinding process, but it had a mere influence when stainless-steel medium was used. Redox potential measurements showed that the grinding environment of stainless-steel medium could exhibit a higher oxidizing potential than the steel grinding environment. Results from FTIR, XPS, and ion concentration measurements demonstrated that more ferric ions existed on the copper activated marmatite surface in the steel grinding environment than that in the stainless-steel environment. Ferric ions could further hinder the activation effect of copper ions on marmatite and result in decreased marmatite flotation. This research could potentially explain the mechanism of ferric ions in the grinding process, and it can be utilized to improve the flotation performance of marmatite ore through selecting suitable grinding media in ball mill operations.