Whiteness is an important indicator of calcium carbonate. In terms of the whiteness of the product alone, calcium carbonate with higher whiteness is more favored by users. Therefore, for manufacturers, how to improve the whiteness of calcium carbonate is also a very critical production technology.
Influencing Factors of Calcium Carbonate Whiteness
1. Calcination
Some manufacturers do not pay attention to the cleaning of the ore. A large amount of soil is calcined in the kiln with the ore. Many harmful impurities such as silica, alumina, iron oxide, etc. will combine with calcium oxide to form a low-melting viscous substance when calcined, making the A “nodulation” accident occurred in the shaft kiln, and the nodules adhered to the surface of calcium oxide, reducing the whiteness of the product.
2. Digestion
Different digestion equipments have different effects on whiteness, digestion tank has the least impact, paddle digestion is the second, and drum digestion machine has the greatest impact.
3. Refined
The refining process is one of the important factors affecting the whiteness of the slurry, and the quality of the refining of the slurry can make a big difference in the whiteness. Refining is to get rid of yellow and black impurities. The more thorough the removal, the higher the whiteness.
How to improve the whiteness of calcium carbonate
(1) It is necessary to strengthen management and improve equipment level. You get what you pay for heavy calcium carbonate production equipment, and timely repair and maintenance of equipment is also important.
(2) The selection of raw ore should be carefully selected. It can analyze whether the iron in the ore exceeds the standard. Generally, it is required that Fe2O3≤0.1%. It can also be treated in the same way. If it is not that the iron exceeds the standard, this method cannot be used, otherwise the whiteness will be reduced instead.
(3) It is necessary to comprehensively analyze the chemical composition of calcite and its product calcium carbonate. If other impurities in the ore exceed the standard, it will also cause low whiteness. At this time, it is necessary to increase the whiteness as much as possible through multi-stage slag removal treatment. Change ore. If it contains high colored minerals, bleaching technology should be used to improve the whiteness of calcium carbonate products.
(4) According to the pigment ions contained in the limestone and the product calcium carbonate, reduction bleaching or oxidation bleaching or both bleaching methods are used respectively. Heavy calcium carbonate bleaching generally puts chemicals into the crushing process, and bleaches while crushing; light calcium carbonate bleaching can be divided into three forms: digestion process bleaching, carbonization process bleaching, and bleaching in cooked pulp.