Introduction of main processing technology of kaolin:
Kaolin processing technology generally includes beneficiation purification, ultra-fine crushing, calcination and surface modification. The original kaolin ore contains kaolinite minerals as the main components, and there are small amounts of montmorillonite, illite, diaspore, quartz, feldspar, mica and iron minerals (limonite, hematite, diamond) Iron ore, pyrite, etc.), titanium oxides (ilmenite, rutile, etc.), organic matter (plant fiber, organic peat, coal) and other impurities. As a mineral filler application, it must be beneficiated and purified.
The processing technology of kaolin depends on the type of ore. Different beneficiation and purification processes are adopted for soft kaolin, sandy kaolin and hard kaolin (kaolinite).
Dry and wet separation are the two main processes of the kaolin beneficiation process. The dry separation process is used to process kaolin ore with high whiteness and low grit content. It is easy to operate and saves costs. The raw kaolin ore is crushed in a crusher, and then the kaolin concentrate can be obtained by grinding in a Raymond mill. Wet kaolin beneficiation process is used to process complex kaolin ore. Wet beneficiation process uses high gradient magnetic separation, foam flotation and selective flocculant to make full use of kaolin mineral resources.
Main production process of kaolin:
1.pounding
The raw ore is added with water and dispersant according to the set concentration requirements, and is made into pulp in a mixer or a tamping machine. The purpose of pulping is to disperse kaolin and separate it from sandy minerals and plant impurities in order to prepare a slurry of suitable concentration for the next process.
2. Spiral classifier to remove coarse sand
The raw particles of kaolin clay such as quartz, feldspar, mica and other impurities have coarser particle sizes, generally larger than 325 mesh, while the particles of kaolin have finer particle sizes, mainly concentrated in -2μm. A spiral classifier can remove most of the quartz and feldspar coarse sand.
3. Sorting of hydrocyclone
The hydrocyclone is used for separation. The operation is to remove kaolin fine sand (fine-grained quartz, feldspar and other impurities). Generally, hydrocyclones with different diameters such as Ø75, Ø50, and Ø25 are used for multiple sorting.
4. Classification of horizontal spiral centrifuge
The horizontal spiral centrifuge is used for classification, and the process parameters (such as separation factor) can be adjusted according to different materials to keep the product quality stable. At present, domestic kaolin beneficiation also adopts hydrocyclone for selective classification, but due to the influence of flow and pressure changes, the product quality is difficult to stabilize at -2μm accounting for more than 90%, and the classification efficiency is not as good as horizontal spiral centrifugal classifiers.
5. Magnetic separation
In order to obtain high-quality or high-quality kaolin, in most cases, strong magnetic separation or high gradient magnetic separation, chemical bleaching, even flotation and selective flocculation are required. The dyed mineral impurities in kaolin, such as limonite, hematite, siderite, pyrite, anatase, rutile, etc., have weak magnetic properties, so the kaolinite after sand removal can be further used strong magnetic separator or high gradient The magnetic separator performs magnetic separation.
Since most of the iron and titanium minerals in kaolin are embedded with finer particle size, the removal rate of strong magnetic separation is generally not high. Therefore, most of the industries currently use high gradient magnetic separators for magnetic separation of kaolin. In addition, superconducting magnetic separators with better performance have also been used for the magnetic separation and iron removal of kaolin. This magnetic separator not only further improves the strength of the magnetic field, but also obtains high-quality high-quality kaolin and reduces energy consumption. If the whiteness index of kaolin after magnetic separation still cannot meet the requirements of high-quality kaolin, chemical bleaching is generally adopted.
The special magnetic separator for washing kaolin is a wet strong magnetic separator. The magnetic strength is up to 16000GS. It can remove the regenerated iron in the kaolin during the kaolin grinding process to improve the whiteness. And other weak magnetic substances.
6. Chemical bleaching
The chemical bleaching of kaolin is often related to the use performance of kaolin and the impurities contained. The main impurities affecting the use performance of kaolin are iron minerals, titanium minerals and organic matter. Commonly used chemical bleaching includes reduction method, oxidation method, oxidation-reduction combined bleaching method, acid leaching treatment method, etc.
7. Pressure filter process
Using high-pressure slurry feeding to improve productivity, ensure product moisture is less than 32 to 35%, save energy consumption and improve working environment.
8. Drying process
Powerful drying can be used.
Kaolin powder specifications:
The specifications of kaolin powder include 100 mesh, 200 mesh, 325 mesh, 800 mesh, 1200 mesh, 2000 mesh, 2500 mesh, 3000 mesh, etc. What kind of equipment is needed to process kaolin ore? It is mainly to determine the finished product according to the use The fineness range belongs to coarse crushing or fine crushing. The equipment used for coarse crushing between 50~325mm is Raymond grinding equipment or ultrafine ring roller mill. The fine crushing is divided into 325~2500 mesh. The equipment is micro-powder grinding equipment such as kaolin powder ultra-fine vertical mill, which can determine which production line is used according to the fineness of the finished product. Regardless of the coarse crushing production line or fine crushing production line, the entire production line includes the crusher and the milling process. For the powder processing of attapulgite, it can be used directly because of its small size.
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