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2 Physicochemical Problems of Mineral Processing

2 2019

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Study of the mechanism for improving green pellet performance with compound binders

Li Caixia, Bai Yang, Ren Ruichen, Liu Gaoquan, Zhao Jingyu

Physicochemical Problems of Mineral Processing

2019

Vol. 55, iss. 1

153--162

In this study, the characters of bentonite organic binders were investigated by analytical methods, including X-ray diffraction, zeta potential, and scanning electron microscope. The results showed that the surfaces and the edges of montmorillonite layers reacted with carboxyl groups or oxhydryl groups of expanded starch or carboxymethyl cellulose (CMC), enhancing the surface electronegativity of the bentonite. The addition of organic binders reduced the contact angle between the bentonite and magnetite and enhanced the hydrophilicity of bentonite surfaces. Based on the polymer chains of organic binders, the house-of-cards structure formed by a compound binder was more stable than when formed by bentonite alone. The non-stripped layers in bentonite were peeled off under the action of chemical bonds. At the same time, improved bentonite dispersion in pellets was observed, with decreased bentonite particle size and increased surface area. The solid bridges produced by the reaction between magnetite and Mg2+ in the montmorillonite layer restrained pellet expansion, which thus improved the decrepitation temperature during the heating process.

Application of sodium dodecyl glycinate to the flotation of deslimed molybdenum tailings

Bai Yang, Li Caixia, Song Wangfang, An Hongyun, Zhao Jingyu

Physicochemical Problems of Mineral Processing

2019

Vol. 55, iss. 5

1120--1131

By researching the nonmetallic minerals in molybdenum tailings, this paper investigated the possible application of sodium dodecyl glycinate (SD) to deslimed tailings as an alternative to the large dosage and complex flotation reagent systems of conventional combination collectors (dodecylamine and sodium oleate). The floatability differences of nonmetallic minerals under different SD dosages were analyzed via pure mineral flotation experiments, and the adsorption behavior of SD onto different mineral surfaces was analyzed by quantum chemical calculations. The results of the calculated adsorption structures and energies of the different mineral surfaces show that SD was chemically adsorbed onto the albite (001), phlogopite (010), diopside (110), dolomite (101), calcite (104) and calcite (101) surfaces and that physical adsorption occurred at the phlogopite (001) surface. The corresponding adsorption trend was dolomite > calcite > diopside > albite > phlogopite. These results theoretically verify the feasibility of applying SD to the flotation of nonmetallic minerals in tailings and provide a basis for the selection of inhibitors needed for separating phlogopite from other minerals. In the flotation of deslimed molybdenum tailings, the recoveries of the nonmetallic minerals achieved with SD were close to those in pure mineral flotation, which was greater than the recoveries achieved with dodecylamine and sodium oleate (NaOl), and the dosage was reduced by approximately 25%.