What are the factors that affect the whiteness of light calcium carbonate?
In the production of light calcium carbonate, most companies pay attention to strict lime selection when controlling the whiteness of the product, which is undoubtedly the main factor in ensuring that the production of light calcium carbonate meets the whiteness standards of users.
However, the influence of factors such as fuel quality, quicklime quality, lime kiln flue gas dust, drying system flue gas, and production environment on the whiteness of light calcium carbonate cannot be ignored. If these factors are not included in the process control or are not strictly controlled or even out of control, it will be difficult for the whiteness of ultra-fine light calcium carbonate to reach the qualified product index or meet user needs. Therefore, to ensure and improve the whiteness of light calcium carbonate, it is necessary not only to start with lime screening but also to comprehensively adjust the relevant factors affecting the whiteness of light calcium carbonate in various production processes. Now let's talk about the degree of limiting the whiteness of light calcium carbonate and the control method.
一. Raw material quality
The raw materials required for the production of light calcium carbonate are lime and fuel anthracite or coke.
Limestone
Limestone is the main factor affecting the whiteness of light calcium carbonate. The main chemical components affecting its whiteness are the content of impurities such as iron, manganese, and hydrochloric acid. When the iron content in limestone is less than 0.12%, the manganese content is less than 0.5%006%, and the hydrochloric acid insoluble content is basically 30% <0.05%, it can meet the production of light calcium carbonate with qualified whiteness. Experienced material receiving and inspection personnel are usually selected according to the appearance of the limestone. Blue-gray and light-gray limestone has high purity and few impurities. Limestone containing a large number of impurities (such as iron, manganese, and hydrochloric acid insoluble) usually has yellow, brown, pink, or brown patterns or spots. In addition, strength can also be judged by the color of quicklime, which creates a good environment for aseptic production. Especially when it contains non-ferrous metal oxides, quicklime is mostly gray-yellow, light yellow to brown, or even black.
Fuel
Due to fuel prices, anthracite is often used to produce light calcium carbonate. The content of impurities such as sulfur and ash in anthracite is also one of the reasons that affect the whiteness of light calcium carbonate. The sulfur content of anthracite used for production is <1.5%, that is, low-sulfur anthracite. If the ash content of anthracite is less than 25%, and the content of other impurities such as alkali stone is less than 20%, it can meet the production process requirements for producing light calcium carbonate with qualified whiteness.
二. Quicklime
In addition to strictly screening the above limestone to ensure the sulfur content and ash index requirements of lime kiln calcined anthracite, the particles and powder in the quicklime should also be controlled below 5mm. In addition, impurities such as coke slag and coke core mixed in quicklime and overburned quicklime should also be selected as clean as possible, which is conducive to ensuring and improving the whiteness of light calcium carbonate.
三. Limekiln smoke
Due to the different specifications, coal quality, and operation of lime kilns, the dust concentration of lime kiln smoke is also different. The dust concentration of kiln gas is generally 1? 10g/m3. In order to reduce the impact of dust in kiln gas on the whiteness of light calcium carbonate, dust removal is usually carried out when conveying kiln gas. The dust particles in the kiln gas are relatively large. Particles larger than 10 meters usually account for more than 80%. Usually, more than 5% of the dust can be removed by using a multi-cyclone dust collector. However, the dust collector should be installed at the near end of the lime kiln. In order to improve the dust removal effect, a water bath dust collector is usually installed in front of the mechanical compressor for kiln gas delivery.