Production methods and application market background and overview of ultrafine calcium carbonate
Calcium carbonate is an important inorganic powder product. Due to its easy availability of raw materials, low price, non-toxicity and high whiteness, it is widely used in rubber, plastics, papermaking, coatings, inks, medicine, food, pyridinedicarboxylic acid Fillers in daily chemicals and other industries to save masterbatch, increase volume and weight, and reduce costs. However, the surface of calcium carbonate powder particles without surface treatment is hydrophilic and oleophobic, and is highly polar. Therefore, it cannot be chemically cross-linked with polymer organic matter such as rubber and plastic. It is difficult to disperse evenly in organic media, so it cannot function as a functional filler. role. On the contrary, some physical properties of the product will be reduced to a certain extent due to interface defects.
The successful application of activated calcium carbonate has made a qualitative leap in the performance of calcium carbonate. In particular, active ultrafine calcium carbonate has the characteristics of a functional filler, which greatly broadens the scope of application. Its toughening and reinforcing effect greatly improves and enhances product performance and quality in related industries. Ultrafine calcium carbonate refers to calcium carbonate whose primary particle size is between 0.02-0.1μm. Japan was the first country to develop ultrafine calcium carbonate. It is still an international leader in development, production and application. It can produce ultrafine calcium carbonate and amorphous calcium carbonate with different crystal forms, different particle sizes and different surface modifications. Wait, there are many varieties. During this period, developed countries such as the United States and the United Kingdom also had their own characteristics in the field of calcium carbonate. The United States focuses on the application of ultrafine calcium carbonate in papermaking and coatings, and is an international leader in the development of coupling agents. In Japan, Europe and the United States, the dosage of ultrafine calcium carbonate greatly exceeds the dosage of light calcium and heavy calcium. Ultrafine calcium carbonate is the finest calcium carbonate and the cheapest nanomaterial. Its special quantum size effect, small size effect and surface effect make it show obvious advantages in reinforcement, transparency, dispersion, thixotropy and leveling compared with conventional powder materials. The advantages. Now, ultrafine calcium carbonate is developing in the direction of specialization, refinement and functionality.
Production methods and application market production methods of ultrafine calcium carbonate
According to the different carbonization processes, the production methods of ultrafine calcium carbonate in my country can be roughly divided into: intermittent bubble carbonization method; continuous bubble carbonization method; continuous spray carbonization method; and hypergravity reaction crystallization method.
Production methods and application markets of ultrafine calcium carbonate 1. Intermittent bubbling carbonization method
According to whether there is a stirring device in the carbonization tower, this method can be divided into ordinary intermittent bubble carbonization method and stirred intermittent bubble carbonization method. Add refined calcium hydroxide suspension and appropriate additives to the conical bottom cylindrical carbonization tower, and then introduce carbon dioxide from the bottom of the tower to carbonize to the end point to obtain the required calcium carbonate product. During the reaction process, reaction conditions such as carbonization temperature, carbon dioxide flow rate, lime milk concentration and stirring speed need to be strictly controlled, and appropriate additives must be added. This method has low investment and simple operation, but the production is discontinuous, the degree of automation is low, and the product quality is unstable. The main manifestations are that the crystal form of the product is difficult to control, the particle size distribution is uneven, and the reproducibility of different batches of products is poor. At present, most domestic manufacturers use this method to produce light calcium carbonate. To produce ultrafine calcium carbonate, the reaction process parameters must be strictly controlled to improve the stability of different batches of products.
Production methods and application markets of ultrafine calcium carbonate 2. Continuous bubble carbonization method
This method is generally a two-stage or three-stage series carbonization, that is, the refined lime milk is partially carbonized in the first-stage carbonization tower to obtain the reaction mixture, and appropriate additives are added to the slurry tank before entering the second-stage carbonization tower. The final product is obtained by carbonization, or then enters the third-stage carbonization tower for carbonization to obtain the final product. Since the carbonization process is carried out step by step, surface activation treatment is carried out between stages, and the carbonization temperature can be controlled by refrigeration. Therefore, the nucleation, growth process and surface treatment of the crystal form are also controlled in stages, so that a better crystal form can be obtained, and a better Small particle size and particle size distribution. Now, some domestic calcium carbonate manufacturers canIn magazine paper, dictionary paper, newsprint, and book paper, the filling amount of calcium carbonate reaches 5-30%. In special paper products such as quantitative coated paper and matte copper paper, the ultrafine calcium carbonate filler can even reach more than 80%. In the United States and Japan, some large-scale ultrafine calcium carbonate plants are built next to large paper mills. Its ultra-fine calcium carbonate slurry does not require activation treatment or dehydration and drying. It is directly transported to the paper mill through pipelines and mixed evenly with the pulp, greatly reducing production costs. In our country, similar “satellite factories” have begun to be put into use and are being built continuously. Different types of paper have different requirements for the crystal form and material diameter of calcium carbonate, and the spindle shape is more commonly used. At present, in the domestic papermaking industry, fine calcium carbonate is widely used, while ultrafine calcium carbonate is rarely used. But it is foreseeable that China’s paper industry will become one of the largest users of ultrafine calcium carbonate in a few years.
Production methods and application markets of ultrafine calcium carbonate 4. Ink industry
The printing ink market requires high-performance ultrafine calcium carbonate. Ultrafine calcium carbonate is used in ink products, showing excellent dispersion, transparency, excellent gloss and hiding power, excellent ink absorption and drying properties. Ultrafine calcium carbonate used in inks must be activated, and the crystal form is spherical or cubic.
Production methods and application markets of ultrafine calcium carbonate 5. Paint industry
In the coating industry, ultrafine calcium carbonate can not only be used as a high-quality whitening pigment, reduce costs, improve the gloss of coatings and paints, and improve the gloss, dryness and hiding power of products, but also has a reinforcing effect. Using ultrafine calcium carbonate to replace the more expensive titanium dioxide can achieve the same effect.
Production methods and application markets of ultrafine calcium carbonate 7. Health food and feed industry
As long as the content of lead, arsenic and other elements harmful to humans and animals in ultrafine calcium carbonate is controlled, ultrafine calcium carbonate can be used in the health food and feed industry as a calcium source additive. It is of high quality, low price and easy to absorb. , has been applied in research on milk powder and other aspects, and has great potential.
Production methods and application markets of ultrafine calcium carbonate 8. Daily chemical and pharmaceutical industry
Ultrafine calcium carbonate can be used as lepidolite filling material for daily chemical products such as high-end cosmetics, soaps, facial cleansers, and children’s toothpaste. In the pharmaceutical industry, ultrafine calcium carbonate is an important component and calcium source additive in the culture medium. It is used as a buffer for microbial fermentation in the production of antibiotics. It also plays a certain pharmacological role in analgesics and gastric medicines. With the continued rapid growth of my country’s economy, the advancement of calcium carbonate miniaturization and surface activity technology, and the need for related industries to improve product quality, the ultrafine calcium carbonate industry will surely achieve unprecedented development in my country.
References
[1] Yan Xin, Liu Yuejin, Wang Peiliang. Production status and application prospects of ultrafine calcium carbonate in my country [J]. Chemical Industry, 2003(01):16-20.
[2]Deng Li, Ji Jie, Jiang Huiliang, Yin Fushan. New exploration of industrial application of surfactants – preparation of ultrafine calcium carbonate [J]. Daily Chemical Industry, 2002(05):14-16.
