Kaolin mines are widely used in papermaking, rubber, plastic, fire resistance and other industrial fields because of its advantages, such as plasticity, bonding and fire resistance. The mineral processing method of kaolin depends on the characteristics and production requirements of raw ore. In the actual production, the beneficiation process of kaolin can be divided into dry type and wet type. Hard-type kaolin often adopts dry beneficiation process, and soft-type kaolin adopts wet beneficiation process. This article will introduce the four wet-type ore dressing processes of kaolin mine, namely, high gradient magnetic separation, foam flotation, selective flocculation and leaching.
Wet process is an important mineral processing process to obtain high purity and quality kaolin, which generally includes three stages of ore preparation, mineral processing and product treatment.
Preparation stage: including matching, crushing and adjusting. During the slurry adjustment, the kaolin raw ore, water and dispersant are put in the agitation tank. The slurry regulation can disperse the raw ore, and the appropriate fine kaolin slurry is prepared for the separation process in advance, and the sand and stone with large particles are removed.
Mineral processing stage: this stage mainly includes hydraulic classifying, flotation separation, selective flocculation, magnetic separation, chemical bleaching and other operations. Through these beneficiation processes, different impurities can be removed to improve the brightness of the product. Each beneficiation process has its own advantages and disadvantages, and the concentrator generally adopts the combined beneficiation process of two or three kinds of processes to improve the comprehensive recovery rate of kaolin.
Product treatment: concentrate and dehydrselected pulp according to production requirements.
Stained impurities such as hematite in kaolin are weakly magnetic and can be removed by high gradient magnetic separator. Because the iron impurities in partial kaolin may exist in the form of silicates. The magnetism is very weak, and the titanium exists in the form of rutile, which is not the ideal impurity removal effect by using the magnetic separation method. Therefore, a combined flotation or selective flocculation process is needed to improve the product quality.
Use the flotation process to remove titanium impurities from kaolin. Because the impurity particles are fine, the carrier flotation process is needed. Calcite and silica sand are generally used for carrier minerals, and their dosage is generally 10% -20% of the weight of kaolin. Some of the carriers can be recycled. During flotation, sodium silicate is used as the dispersant of pulp, amine hydroxide and caustic soda are used as pH regulator, while trap oil, fatty acid and oil calcium-sulfonate are selected.
When the pH value of the pulp is 8-11, the alkaline metal ions with calcium and magnesium ions are added. At this time, the iron and titanium impurities in the pulp will selectively condense, and then a weak anionic polymerized electrolyte is added to the pulp to select flocculation. The process requires adjusting the slurry concentration to less than 20%. A lot of water needs to be removed later. When the selective flocculation of kaolin is polymer flocculant, the kaolin particles flocculate each other and sink to the bottom, and the iron and titanium impurities are suspended on it in reddish brown. If this suspension is removed, most of the iron and titanium impurities can be removed, and then the high quality kaolin can be obtained by using other mineral processing processes.
The condition of leaching is generally in the weak acidic solution, in the presence of reducing agent. Such conditions can keep the dissolved iron in a bivalent state, avoid the formation of trivalent iron, and then use water washing to separate it from kaolin. Dark organic impurities can be used as strong oxidizants such as hydrogen peroxide, sodium hypochlorite for bleaching.
The above contents are the four techniques of kaolin mines wet dressing. Due to the different ore characteristics of kaolin, the specific mineral processing method should be adjusted appropriately, and sometimes it is necessary to combine the separation of several mineral processing processes to improve the product quality and concentrate recovery rate. Xinhai Mining can provide the analysis of kaolin beneficiation test, and customize the beneficiation plan according to the test results to improve the production efficiency and economic benefit of the dressing plant.
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