Comprehensive utilization technology of diatomite

Diatomaceous earth is a bio-genetic siliceous sedimentary mineral. In the ore, a large amount of organic matter and clay minerals are often mixed, and the impurities present in the pores of diatomite are difficult to remove by conventional beneficiation methods, although acid leaching Can improve the grade of diatomite, but due to the strong adsorption capacity of diatomaceous earth, some impurities in the acid solution will enter the diatom, and the cost of pickling is high, and it is easy to cause serious environmental pollution; usually diatomaceous earth The processing process of ore dressing is: raw ore - one section of grinding and drying - two sections of grinding and drying - pre-sorting - cyclone separation - powdery products. If further processing is required, it is sent to the rotary kiln for calcination (with or without flux) - grinding cooling - sorting and grading - filler grade or filter aid grade products.

Due to the different grades of ore and different requirements for diatomite products, dry or wet beneficiation is used respectively. The principle and application range are listed in Table 1. In many fields, the porosity of the diatomite silicon shell structure is utilized. During processing, attention must be paid to protecting the structure and unique shape of the diatom skeleton, and carefully selecting suitable crushing and grinding equipment and process conditions to protect the diatom structure to the greatest extent possible. Complete to avoid secondary crushing. A common grinding device is a jet mill.

Development production example

At present, there is not a relatively complete diatomite beneficiation processing plant in China. Only a few units have engaged in the beneficiation and purification of low-grade diatomaceous earth, and have not yet formed production capacity.

Beneficiation and purification of a diatomite ore in western Yunnan

The mine is a clay diatomaceous earth with good texture. It is determined that the diatomite is mainly Navicula, followed by the algae, the algae and the algae. Through sieving analysis, -25mm accounted for 51.97%, the distribution ratio of SiO2 was 63.05%, the grade was 86.60%, which was much higher than that of the original soil SiO284.56%. Therefore, the method of pre-screening to remove the coarse fraction can be improved. grade. The physical and chemical properties of the original soil are listed in Tables 2 and 3. The magnetic separation test, the magnetic-heavy separation test, the selective flocculation-magnetic-heavy separation test, the activation roasting test, and the like. The results are shown in Table (4-7). Magnetic separation can effectively remove Fe2O3 from the original soil, and obtain products with SiO2 content of 87.89% and Fe2O3 content of 0.27%. Flocculation-magnetic-heavy separation can effectively separate diatom particles with small specific magnetic susceptibility and fine particle size. Selective flocculation can flocculate impurities such as Fe2O3 into agglomerates, making it into larger particles for magnetic separation and re-separation separation. Activated roasting can not only remove organic matter in diatomaceous earth, but also purify. When the activation roasting temperature is 700-800 ° C, the activation effect is best, and the grade of the refined soil can be increased by 2 to 5 percentage points.

In summary, in the case of the original soil SiO2 of 84.56%, Al2O3 of 3.77%, and Fe2O3 of 0.56%, the pre-staged de-mixing-selective flocculation-magnetic re-separation separation process can be used to obtain diatomite soil suitable for the production of filter aids. (See Table 7). The method has been used to build factories. After the ore dressing clay is calcined, the indexes are: SiO296.71%, Fe2O30.63%, Al2O31.67%, CaO 0.2%, and MgO 0.10%.

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