There are two main production methods for heavy calcium carbonate: dry method and wet method. The dry method generally produces heavy calcium below 2500 mesh. It is technically feasible to produce heavy calcium above 2500 mesh, but the energy consumption and cost are higher. , It is not economically feasible. The production of ultra-fine heavy calcium carbonate above 2500 mesh mainly uses wet grinding, and dry grinding is used as the first step of wet grinding.
Dry production of heavy calcium is currently a common method in China, and the technology is relatively mature. Generally, products of various particle sizes can be obtained by using a processing technology system composed of grinding equipment and grading equipment. The main equipment used is Raymond mill, ring roller mill, ball mill, high-pressure roller mill, stirring mill, vibration mill, impact mill, etc. The classification equipment mainly adopts impeller type superfine classifier. among them:
Raymond mill is used to produce 38-74μm (200-400 mesh) products in large quantities. After modification and configuration of a fine classifier, it is also used to produce fine powder with d97=30-15μm (500-800 mesh);
The ball mill is the main equipment of the large-scale heavy calcium carbonate production line. After configuring various classifiers, it is used to produce heavy calcium carbonate products of d97=5μm, 10μm, 16μm, 45μm, etc.;
The vibrating mill is equipped with fine grading equipment mainly used to produce d97=5μm, 10μm, 16μm products, but its stand-alone production capacity is not as good as ball mills;
The mechanical impact mill has simple process, but low output, mainly used in small and medium-sized heavy calcium carbonate production plants;
Dry stirring mills are used in large-scale heavy calcium carbonate production plants in Europe, but there are few applications in China.
The dry production process has the characteristics of low equipment investment, mature technology, simple process, low energy consumption and high single machine output.
With the development of heavy calcium carbonate becoming more and more refined, the traditional dry production process cannot meet the requirements in terms of equipment itself or economic benefits, and the wet grinding process has emerged. The biggest difference between wet grinding and dry grinding is the difference in the dispersion medium. Dry grinding uses air as the dispersion medium, while wet grinding uses water as the dispersion medium and is equipped with grinding aids to make the particles more dispersed. The grinding efficiency is higher and the particle size is finer.
After washing, the raw ore is crushed to about 400 meshes in two stages, prepared into a slurry of a certain concentration, added with grinding aids, and fed into the vertical grinder, with zirconia beads as the grinding medium, and the discharge is controlled by adjusting the parameters of the mill Fineness, the material is discharged in the form of slurry after being ground, and collected and bagged after drying and dust removal.
Because the production process and grinding environment of wet grinding heavy calcium are obviously different from dry grinding heavy calcium, there are also obvious differences in the physical properties of its products.