Processing of Wollastonite and Its Application in Coatings

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1、 Overview:

Wollastonite belongs to a type of chain like metasilicate, usually in the form of fibers or needles. Due to its unique crystal morphology and crystal structure, wollastonite has excellent insulation properties, as well as high whiteness, good dielectric properties, and high heat and weather resistance. Wollastonite is widely used in fields such as ceramics, chemical engineering, metallurgy, papermaking, plastics, coatings, etc.

2、 Processing of Wollastonite

（1） Beneficiation

The main methods for beneficiation of wollastonite at home and abroad are manual separation, single magnetic separation, flotation, and a combined process of magnetic separation flotation (or electric separation). The main purpose of mineral processing is to reduce iron content and separate calcite.

(1) Manual selection

The mining site manually selects rich ore blocks or crushes them on the conveyor belt, and manually selects rich wollastonite ore blocks. Hand selection is suitable for high-quality ores.

(2) Single magnetic separation

The main accompanying minerals in wollastonite rocks, such as diopside and garnet, belong to weakly magnetic minerals, while wollastonite shows little magnetism. Therefore, dry or wet strong magnetic separation techniques can be used to separate wollastonite from each other, which can separate a large amount of iron containing minerals and improve product purity.

(3) Single flotation

Based on the differences in surface physicochemical properties between wollastonite and calcite minerals, flotation can effectively separate them from each other, thereby improving the purity of wollastonite products.

(4) Magnetic separation flotation combined process

This method is suitable for the treatment of low-grade wollastonite. Firstly, dry or wet magnetic separation is used to separate weakly magnetic minerals. Then, flotation method is used to separate wollastonite from minerals such as calcite and quartz. Flotation separation of wollastonite and calcite. There are two main processes for minerals such as quartz.

①Anionic collector reverse flotation scheme

Calcite is a carbonate type mineral, while wollastonite and quartz belong to the silicate type mineral. Based on the differences in surface electrical properties between the two, adjusting agents are used to suppress wollastonite by changing the pH value of the slurry medium, and calcite is separated by flotation. Then, quartz and wollastonite are separated by flotation. Generally, oxidized paraffin soap is used as a collector for calcite, and sodium silicate is used as an inhibitor for wollastonite and quartz.

②Cationic collector positive flotation scheme

This method mainly adjusts the surface electrical properties of wollastonite and calcite minerals to bring different sign potentials, and then uses cationic collectors to preferentially float wollastonite through electrostatic adsorption, while calcite is left as tailings in the flotation tank. The flotation operation is divided into two stages: the first stage uses amine collectors to float wollastonite and silicate minerals together as foam products, while calcite is left in the tank; The second stage uses a mixed collector of amine ions and anions for flotation of silicate impurities, while wollastonite is recycled as a product in the tank.

（2）Crushing and processing of needle shaped wollastonite

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