Lime was first used in China in the 7th century BC. Lime is still a widely used building material. Lime has been used in building bricklaying, mortar wall painting, and other adhesive materials for a hundred years. Due to its wide distribution of raw materials, production technology through the development of modern science and technology, continuous research and development, suitable for all walks of life.
Lime deep processing products
At present, lime deep processing products include nano calcium, light calcium, calcium hydroxide, lime calcium powder, desiccant, food calcium, medical calcium, calcium oxide powder, and lime products with high activity, high content, and high specific surface area. In recent years, especially the environmental protection products have developed rapidly, and from the original extensive processing to the refined direction, from scattered small random to large-scale direction. Therefore, the development of high-grade lime deep processing products is a trend of China's lime industry.
Nano calcium carbonate
Due to the superfine of Nano-CaCO3, the crystal structure and surface electronic structure of Nano-CaCO3 change, resulting in the surface effect, small size effect, quantum size effect, and macro quantum effect that ordinary CaCO3 does not have. Compared with other fillers, nano calcium carbonate has great advantages in dispersion, reinforcing effect, functionality, and cost. As an inorganic functional filler, nano calcium carbonate has been widely used in all walks of life, such as plastics, rubber, adhesives, coatings, ink, paper, and other industries.
Light calcium carbonate
Light calcium carbonate is a white powder, odorless and tasteless, with low bulk density. The demand for light calcium carbonate in some developed countries and regions is mainly concentrated in papermaking, plastics, coatings, paints, adhesives, and sealants. In China, light calcium carbonate products are mainly used in papermaking, plastics, coatings, rubber, ink, adhesives, daily chemical industry, and other fields.
Hydrated lime is calcium hydroxide obtained by dissolving quicklime in water. Because the hydrated lime is generally produced by the digestion reaction of quicklime, so the hydrated lime is also called hydrated lime. Hydrated lime (calcium hydroxide) is used in pharmaceutical, rubber, petroleum industry additives, and softened water. It can be used in the petroleum industry to add lubricating oil to prevent coking, sludge deposition, neutralization, and anticorrosion.
Lime calcium powder
The main component of lime powder is the mixture of Ca (OH) 2, Cao, and a small amount of CaCO3, which is the finished product of lime. It is made of natural high-quality limestone with CaCO3 as the main component, which is calcined at high temperature to become quicklime (CAO), then selected and partially digested, and then crushed by a high-speed air separation hammer crusher. Its appearance is white and delicate. Lime calcium powder is a kind of active filler, which can give the coating good water resistance, wash resistance and enhance other physical and mechanical properties of the coating. Lime powder can be divided into three types of uses: high-grade products used in the field of food and medicine; Medium grade products are used in the field of coatings; Low-grade products are used in water treatment and desulfurization.
Calcium oxide powder
Quicklime (CAO) can be used in iron and steel, pesticide, medicine, non-ferrous metal, fertilizer, leather making, calcium hydroxide making, ammonia drying, and alcohol dehydration in the laboratory, etc.
Deep processing technology of lime
China's annual output of lime is more than 300 million tons, accounting for more than half of the world's total. However, compared with the world lime industry, especially the calcination technology, production environment, and deep processing of developed countries, there is still a certain gap. The quality of most limestone in China is not inferior to that of foreign countries. Moreover, some foreign deep processing enterprises purchase lime from China and sell it back to China after deep processing. The price increases several times. This shows that the deep processing technology of lime in China is relatively backward and needs to be developed.
First of all, the requirements for raw material lime. Deep processing lime is different from other uses, such as metallurgical ash and highway ash. The higher the content of calcium oxide, the better, and the lower the content of silicon, magnesium, and other heavy metals, the better. Because the content of deeply processed products is the main factor to determine the price.
Because the proportion of deep processing lime in the calcination process must be higher, so the requirements for raw materials are particularly high.
① the diameter of limestone should be uniform;
② the silicon content should not be too high;
③ limestone should be washed with water;
④ coal should be low volatile;
⑤ calcination should be dynamic.
The above five points are for deep processing lime must be calcined evenly, not too much raw burning. The content of the product is increased. In particular, the production of high-grade products must be good raw materials, calcination, to have higher added value. The positioning of market products is the key to the selection of equipment.
Secondly, the quality of the calcination process is the problem faced and solved by enterprises. Making full use of the original calcium oxide content of limestone to release carbon dioxide and maximize the effective calcium oxide content can only be achieved through scientific and reasonable calcination.
In addition, corresponding to different deep processing products, the selected raw materials, deep processing technology, and equipment are different, and they also face different difficulties and problems.