Kaolin wet mineral processing technology

The wet process is an important beneficiation process to obtain high-purity and high-quality kaolin. It generally includes three stages: ore preparation, mineral processing and product processing.

Preparation stage: including proportioning, crushing and pulping. During slurry mixing, kaolin raw ore is pulped with water and dispersant. The slurry mixing operation can disperse the raw ore, prepare kaolin slurry with appropriate fineness for the separation process in advance, and remove larger sand and gravel at the same time.

Ore dressing stage: This stage mainly includes hydraulic classification, flotation separation, selective flocculation, magnetic separation, chemical bleaching and other operations. Through these sorting processes, different impurities can be removed and the brightness of the product can be improved. Each mineral processing technology has its own advantages and disadvantages. The mineral processing plant generally adopts a combined mineral processing process of two to three processes to improve the comprehensive recovery rate of kaolin.

Kaolin High Gradient Magnetic Separation Technology

The dyed impurities such as hematite in kaolin have weak magnetism and can be removed using a high gradient magnetic separator. Because some of the iron impurities in kaolin may exist in the form of silicates. The magnetism is very weak, and titanium exists in the form of rutile. This is why the magnetic separation method cannot achieve the ideal impurity removal effect. Therefore, it is necessary to combine flotation or selective flocculation and other processes to improve product quality.

Kaolin foam flotation technology

The flotation process is generally used to remove titanium impurities from kaolin. Because the impurity particles present are relatively fine, a carrier process is required. Calcite and silica sand are generally used as carrier minerals, and their dosage is generally 10%-20% of the weight of kaolin. Some carriers can also be recycled and reused. During flotation, sodium silicate is used as the dispersant of the slurry, amine hydroxide and caustic soda are used as the pH adjuster, and tar oil, fatty acids and calcium petroleum sulfonate are selected as the collectors.

Kaolin selective flocculation technology

When the pH value of the slurry is 8-11, alkaline metal ions of calcium ions and magnesium ions are added. At this time, the iron and titanium impurities in the slurry will selectively agglomerate, and then a weak anionic polyelectrolyte is added to the slurry for selective flocculation. This process requires the slurry concentration to be adjusted below 20%. A lot of water needs to be removed later. When the selective flocculation of kaolin uses a polymer flocculant, the kaolin particles flocculate with each other and sink to the bottom, while the iron and titanium impurities are suspended above and appear reddish brown. Removing this layer of suspension can remove most of the iron and titanium. impurities, and then other beneficiation processes can be used to obtain high-quality kaolin clay.

Kaolin leaching technology

The leaching conditions are generally in a weakly acidic solution with a reducing agent. Such conditions can keep the dissolved iron in the divalent state to avoid the formation of trivalent iron, which can then be separated from the kaolin by washing with water. Dark organic impurities can be bleached using strong oxidants such as hydrogen peroxide, sodium hypochlorite, etc.

The above content is the four technologies of kaolin wet beneficiation. Due to the different ore characteristics of kaolin, the specific beneficiation process should be adjusted appropriately. Sometimes it is necessary to combine several beneficiation processes at the same time to improve product quality and concentrate recovery rate.