Calcite Mineral And Its Property
2022-09-20
Calcite is a natural calcium carbonate mineral and the main raw material for the production of heavy calcium carbonate. The grade and impurity content of calcite ore are one of the important factors affecting the quality index of heavy calcium carbonate products.
To comprehensively evaluate the quality of calcite ore, the following items should generally be tested, including: CaO, whiteness, hydrochloric acid insoluble matter, MgO, SiO2, Al2O3, Fe2O3 (TiO2), MnO, CO2, heavy metals (Pb, Hg, Cr6+, Cd), barium, fluorine, arsenic, alkali metals, reducing sulfur, as well as dark foreign matter content, yellowness, transparency, etc., in order to have a comprehensive understanding of the quality of the ore, clarify the direction of its use, and provide users with different uses. refer to. Among them, the content of dark foreign matter, yellowness, and transparency depend on the requirements of the application manufacturer.
1. CaO content
CaO is the only ore useful component quality mark. It is expressed by the content of CaCO3 (which can be converted from the content of CaO) in the requirements of papermaking, coatings, plastics, rubber and food industries.
2. Whiteness
Whiteness is the physical quality indicator of ore, which is related to the chromaticity and brightness of finished products.
3. Hydrochloric acid insoluble matter
The components of hydrochloric acid insoluble matter (A.I.R) are mainly minerals such as free silica (fSiO2), (aluminum) silicate and iron and manganese oxides, which are indicators of multi-mineral composition.
Among them, minerals such as tremolite, actinite, diopside, feldspar, and garnet in fSiO2 and (alumino)silicates have high hardness, which have great impact on the quality of heavy calcium carbonate and processing equipment (including heavy calcium carbonate processing). and its application products processing) have a certain impact, but (alumino)silicates are not common in most ores. Minerals such as sericite, muscovite, talc and kaolinite in (aluminum)silicates have less effect.
Therefore, the key in the hydrochloric acid insoluble is the SiO2 content, which should be evaluated separately if necessary, and the general content should not be greater than 0.5%.
4. MgO content
MgO is mainly used to evaluate the content of dolomite in the ore. In the papermaking and plastic industries, when the content of dolomite is less than 3% (equivalent to MgO≤0.65%), the impact is not significant. In the coatings and rubber industries, this requirement can be relaxed to 6% (equivalent to MgO≤1.3%). MgO from talc and serpentine is generally considered to have little effect.
5. SiO2 content
SiO2, various ores tests show that it is mainly from fSiO2, aluminosilicate and silicate minerals. Among them, the silicate minerals are mainly wollastonite, which has a certain difference in hardness from calcite, which affects the uniformity of product particle size.
6. Al2O3 content
Al2O3 mainly comes from aluminosilicate minerals and is one of the main components of hydrochloric acid insolubles. The allowable value should not be greater than the limit value of hydrochloric acid insolubles. Knowing the content of Al2O3 helps to analyze the mineral composition of hydrochloric acid insolubles.
7. Fe2O3 content
Fe2O3 is a color-causing component, and its content has an impact on the color of the product. According to the experience used in the industry, Fe2O3≤0.3% has no significant effect, and Fe2O3≤0.1% has almost no effect. Fe2+ exists in a variety of minerals. If the price changes during processing or utilization, attention should be paid to its impact.
8. MnO content
MnO mainly comes from manganese oxides, carbonate minerals and silicate minerals in calcite ore. MnO affects whiteness. There is no requirement for manganese in the current industry standards. In the past indicators, the application of the rubber industry requires control of its content. It is generally believed that as long as the calcite ore meets the whiteness requirements, it will have no effect on the product, but Mn is a variable price element, and there may be color changes due to the variable price during processing.
9. Content of harmful substances
Heavy metals, barium, fluorine, arsenic, free alkali, (alkali metal + magnesium), sulfur and other indicators. Those used as food additives, toothpaste and food packaging paper, or for rubber products, plastics and paint fillers that have an impact on health, need to evaluate these indicators.
10. Dark foreign matter content
The content and particle size of dark-colored foreign matter have a certain influence on the whiteness. Under the existing conditions, it is recommended to conduct qualitative statistics on the content of dark-colored foreign matter and particles to evaluate whether it is suitable for ultra-fine processing. When the content of heavy calcium carbonate dark foreign matter in the paper industry exceeds a certain content, it should be used as an evaluation index. Generally, there should be no more than 5 dark foreign particles per gram of sample.
11. Yellowness and transparency
The currently detected whiteness, also known as blue light whiteness, is actually the brightness of the material and cannot reflect the color difference of the material well. Therefore, the heavy calcium carbonate for papermaking needs to evaluate the yellowness and transparency. The paper industry wants low yellowness, low transparency, and good hiding. Calcite with high whiteness tends to have better transparency
