Ningning Zhang

Semi-industrial experimental study on bauxite separation using a cell–column integration process

The cyclonic-static micro-bubble flotation column (FCSMC) is a highly efficient mineral processing equipment. In this study, a cell-column (FCSMC) integration process was investigated for the separation of bauxite and its feasibility was analyzed on a theoretical basis. The properties of low-grade bauxite ore from Henan Province, China were analyzed. Parameters such as reagent dosage, scraping bubble time, and pressure of the circulating pump during the sorting process were investigated and optimized to improve the flotation efficiency. On the basis of these parameters, continuous separation experiments were conducted. Bauxite concentrate with an aluminum-to-silicon (A/S) mass ratio of 6.37 and a 77.63wt% recovery rate were achieved via a flow sheet consisting of “fast flotation using a flotation cell, one roughing flotation and one cleaning flotation using flotation columns”. Compared with the full-flotation-cells process, the cell–column integration process resulted in an increase of the A/S ratio by 0.41 and the recovery rate by 17.58wt%. Cell–column integration separation technology represents a new approach for the separation of middle-to-low-grade bauxite ore.

Prediction of the Ash Content of Flotation Concentrate Based on Froth Image Processing and BP Neural Network Modeling

The concentrate ash content is the most effective evaluation index in the flotation process. However, the ash content obtained by the current technology has a serious hysteresis. In this study, a r...

A review of the surface features and properties, surfactant adsorption and floatability of four key minerals of diasporic bauxite resources

Diasporic bauxite represents one of the major aluminum resources. Its upgrading for further processing involves a separation of diaspore (the valuable mineral) from aluminosilicates (the gangue minerals) such as kaolinite, illite, and pyrophyllite. Flotation is one of the most effective ways to realize the upgrading. Since flotation is a physicochemical process based on the difference in the surface hydrophobicity of different components, determining the adsorption characteristics of various flotation surfactants on the mineral surfaces is critical. The surfactant adsorption properties of the minerals, in turn, are controlled by the surface chemistry of the minerals, while the latter is related to the mineral crystal structures. In this paper, we first discuss the crystal structures of the four key minerals of diaspore, kaolinite, illite, and pyrophyllite as well as the broken bonds on their exposed surfaces after grinding. Next, we summarize the surface chemistry properties such as surface wettability and surface electrical properties of the four minerals, and the differences in these properties are explained from the perspective of mineral crystal structures. Then we review the adsorption mechanism and adsorption characteristics of surfactants such as collectors (cationic, anionic, and mixed surfactants), depressants (inorganic and organic), dispersants, and flocculants on these mineral surfaces. The separation of diaspore and aluminosilicates by direct flotation and reverse flotation are reviewed, and the collecting properties of different types of collectors are compared. Furthermore, the abnormal behavior of the cationic flotation of kaolinite is also explained in this section. This review provides a strong theoretical support for the optimization of the upgrading of diaspore bauxite ore by flotation and the early industrialization of the reverse flotation process.

Arsenic in coal: modes of occurrence and reduction via coal preparation - a case study

ABSTRACT As one of the hazardous trace elements present in coal, removal of arsenic has been overlooked from the point of coal preparation. In this paper, we found that arsenic in coal is associated with pyrite. The various modes of arsenic occurrence via the sequential chemical extraction procedure were sulfide associated form > silicate associated form> carbonate associated form > organically bounded form> ion-exchangeable form. The float-sink test results showed that most of the arsenic was distributed in the high-density fraction, and the reduction of arsenic can be as high as 35.82%. Due to the existence of organic arsenic in coal, the <1.4 g/cm3 fraction is higher in arsenic than 1.4 ~ 1.5g/cm3 fraction. The reduction of arsenic by flotation remained above 50%. Research on organic arsenic in coal is the cruxes to break through for the reduction limit of toxic elements by preparation. The purpose of this article is to facilitate the understanding on the reduction of arsenic in coal by coal preparation and assist the further purification technology of arsenic in coal.