Nanjing Dolomite Mine

(1) The nature of the ore: mine are minor deterioration of marine mines chemical deposition technique, mainly dolomite mineral, there are small amounts of calcite, chalcedony, gypsum, hematite, clay and quartz. The ore structure is dominated by microcrystalline-trapped fine-grained inlaid structures, and oblique layering is observed. The veins are in integrated contact with the stratum and the boundaries are clear. Ore characteristics: the appearance is yellowish brown, purple red, yellowish white. The fractures in the mining area are developed, and their characteristics are mostly tightly closed, and a few are filled with clay.
The ore of this mining area has good quality, high MgO content, low content of impurities such as SiO ₂ and 70% of special grade products. The geological industrial indicators of the mining area and the chemical composition of each grade are shown in Table 1. The main physical properties of the ore: Platts hardness 8~9, density 2.76t/m ³ , looseness factor 1.5, humidity less than 2%.

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(2) Process flow: The mine has two production systems, Shannan and Shanbei. The main processes of the process are basically the same, and the total design scale is 1.5 million t/a. In 1985, the old system of Shannan treated the flux mine to 10,000 tons, which is divided into six. Grade-level; Shanbei New System handles 540,000 tons of building materials and mines, which are divided into five grades. The production process of the crushing and screening plant is shown in Figure 1. The main equipment is shown in Table 2. The quality of raw ore produced and the quality of each product are shown in Table 3. The yield of each grade product is shown in Table 4.

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The processing process of the mine has no washing operation, and the MgO and SiO ₂ content of the flux finished ore is basically close to the geological average grade, which indicates that the ore body has less cracks and less soil, especially the mining work is effective against the veins and soil. The elimination of the product guarantees the quality of the product; as can be seen from Table 2, the content of MgO in the raw ore and each grade product is more than 20%, and the SiO ₂ is basically less than 2%, reaching the special grade and grade 1 of the ministerial standard. Product indicators, the quality of the mine products is good, production is stable, the products are used by Baosteel, Maanshan Iron and Steel, Nangang, Wuhan Iron and Steel, Shougang and other steel companies. Part of the flux minerals used as building materials and mines is a pity. Because the building materials and minerals only require physical properties such as particle size and hardness, there is no strict requirement for the content of MgO and SiO ₂ , so according to the conditions of rock deposits, the mining is unqualified. It is reasonable to use flux minerals as building materials and mines, so that resources can be fully utilized, the cost of flux mines can be reduced, and the economic benefits of enterprises can be improved. The production capacity of the plant was 250~350t/h, and the load of one screening machine was large, which affected the screening efficiency, especially in rainy days. The mine produces building materials and minerals for various purposes and dolomite powder for chemical and glass feed applications. The product specifications and uses are shown in Table 5.

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