What are the applications of calcium carbonate_Industrial additives

What are the applications of calcium carbonate [Background and Overview]

The chemical formula of calcium carbonate is CaCO₃. It is white crystal or powder with a relative density of 2.7 to 2.93. It is a carbonate widely distributed in nature. Natural minerals include calcite, chalk, marble and limestone. It can decompose into carbon dioxide and calcium oxide when heated to about 900°C under a pressure of 101.325kPa. It is difficult to dissolve in water. At 20℃, 100g of water can only dissolve 0.0013g of calcium carbonate. It dissolves in water saturated with carbon dioxide to form calcium bicarbonate, and dissolves in acids (including acetic acid) to release carbon dioxide. Calcium carbonate precipitates can be generated by the interaction between soluble calcium salts and carbonates, or by introducing carbon dioxide into saturated lime water. The resulting powder is called precipitated calcium carbonate or light calcium carbonate.

Calcium carbonate is mainly used in the construction industry, such as cement, lime, artificial stone, etc.; it is also used as chemical raw materials, such as carbon dioxide production, syrup clarifier, Fillers and raw materials for toothpaste, etc.; Used as antacids in medicine, which can neutralize gastric acid, protect ulcer surfaces, and are used for conditions such as hyperacidity, gastric and duodenal ulcers. Calcium carbonate preparations are the most widely used, the best calcium supplements with the highest calcium content, good effects, and low prices. The Drug Information (USP ID) of the United States Pharmacopeia in 1989 introduced that 10 of the 16 commonly used oral calcium preparations are calcium carbonate tablets. Calcium carbonate tablets were quickly used clinically as calcium supplements because they were cheap and had no side effects. Calcium carbonate also has disadvantages. First, calcium carbonate is an insoluble inorganic compound and is weakly alkaline. In the body, anhydrous calcium carbonate reacts with gastric acid to release calcium ions and is absorbed by the body. However, long-term use will consume a large amount of gastric acid and cause indigestion and Abdominal bloating and other problems, calcium absorption is not ideal for those with achlorhydria; secondly, calcium carbonate particles are thicker, taste worse, and have a bitter feeling, so it is poorly accepted by children, and calcium is difficult to absorb in the human body absorbed. In order to solve the above shortcomings, calcium carbonate effervescent preparations came into being.

What are the applications of calcium carbonate [Classification]

According to the processing method, calcium carbonate is divided into heavy calcium carbonate, light calcium carbonate and activated calcium carbonate.

1. Heavy calcium carbonate: The mass fraction of calcium carbonate is generally 0.90 to 0.97. The particles are flaky or irregular, and the particle size is about 10 μm. The relative density of domestic heavy calcium carbonate is 2.6 to 2.8, and the whiteness is 74% to 78%. Heavy calcium carbonate is mainly used as a filler for rubber, and can also be used as a colorant, desiccant, release agent and release agent. Heavy calcium carbonate is cheap and has good mixing and processing properties with rubber and good stiffness of the rubber compound. It is mostly used in molded, extruded and foamed rubber products such as heels, soles, tapes, floors and hoses. The general dosage is 50 ~ 80 servings, maximum dosage up to 230 servings.

2. Light calcium carbonate: also known as precipitation calcium carbonate, its mass fraction of calcium carbonate is generally 0.97~0.99, the particles are spindle-shaped or columnar, the particle size is 0.5~6 μm, and they are linear. The relative density of domestic light calcium carbonate is 2.4 to 2.7, and the whiteness is 80% to 90%. Light calcium carbonate is mainly used as a white reinforcing filler for rubber. It is easily dispersed in the rubber compound and has semi-reinforcing properties. It can improve the tensile strength, tear strength and wear resistance of vulcanized rubber. It is mostly used in conveyor belts, For hoses, tapes, rubber shoes and medical rubber products, the general dosage is 20 to 40 parts, and the maximum dosage can reach 140 parts.

3. Activated calcium carbonate: mainly refers to ultra-fine activated calcium carbonate with a particle size of 1 to 100 nm, also known as nano-calcium carbonate, with a relative density of 2.5 to 2.6. Nano calcium carbonate has high activity, and its reinforcing performance is much better than that of light calcium carbonate, which is equivalent to precipitated silica, but it generates a lot of heat when the rubber compound is mixed. Nano calcium carbonate is mostly used in bicycle tire inner tubes and outer tires, and automobile tire inner tubes

What is the application of calcium carbonate [content determination]

What are the applications of calcium carbonate 1. Calcein method

(1) The main reagents are 10% dilute hydrochloric acid, 10% potassium hydroxide solution, 0.05% methyl red indicator solution, and calcein indicator (take 10g of potassium oxide, grind it finely, add 0.1g of calcein, and grind evenly) , 0.05mol/L disodium ethylenediaminetetraacetate solution.

(2) Take a sample of 0.12g for measurement, weigh it accurately, put it in a conical flask, add 5ml of dilute hydrochloric acid, and dissolve it when heated. Add 150ml of water and 1 drop of methyl red indicator solution, and add dropwise 10% potassium hydroxide solution until it becomes visible. Yellow, continue to add 10 ml more, add 20 to 30 mg of calcein indicator, and titrate with 0.05 mol/L disodium ethylenediaminetetraacetate until the yellow-green fluorescence of the solution disappears and turns orange. Each 1ml of disodium ethylenediaminetetraacetate standard solution is equivalent to 5.004mg of calcium carbonate.

What are the applications of calcium carbonate 2.Calcium indicator method

(1) Main reagent: 10% triethanolamine aqueous solution, other reagents are the same as before.

(2) During the operation, take a sample of 0.12g, weigh it accurately, add 15ml of dilute hydrochloric acid, heat to dissolve, add 100ml of water, 10ml of 10% triethanolamine solution (add 5ml of 1% cysteine ​​solution when containing heavy metal ions), Take 1 drop of 0.05% methyl red indicator solution, add 10% potassium hydroxide solution dropwise until it turns yellow, continue to add 10ml more, add 0.1g of calcein indicator, and titrate with 0.05mol/L disodium ethylenediaminetetraacetate until the solution is From purple to pure blue.

What is the application of calcium carbonate [Application]

1. Application of calcium carbonate in rubber products

In recent years, with the rapid development of my country’s rubber industry, the amount of calcium carbonate has continued to increase.

1) Tires: Light calcium carbonate and nano-calcium carbonate often partially replace low-structure carbon black and white carbon black for car tire outer tire rubber (amount of more than 70 parts) and inner tube rubber, automobile tire carcass cord rubber, Airtight layer

In rubber, inner lining rubber and inner tube rubber to reduce production costs. In addition, the combination of nano-calcium carbonate and ultra-fine active zinc oxide instead of ordinary zinc oxide can improve the tensile strength, elongation at break, flex resistance and fatigue resistance of car tire tread rubber.

2) Hose and tape: Light calcium carbonate and nano-calcium carbonate are used in hose and tape. One is to act as a white reinforcing filler, and the other is to improve the dispersion of the rubber compound. Calcium carbonate can be used in ordinary hoses, colored hoses, hydraulic hoses and short fiber reinforced hoses, etc. In adhesive tapes, it can be used in conveyor belts, transmission belts and synchronous belts, etc.

3) Rubber shoes: Calcium carbonate can adapt to different color requirements and can improve the mixing and extrusion performance of rubber materials. It is widely used in rubber shoes and is often used together with carbon black, white carbon black, titanium dioxide and clay. Used for the uppers, soles and heels of rubber shoes.

4) Wires and cables: Calcium carbonate is generally used together with carbon black, white carbon black, clay and talc powder, etc., and is used as reinforcement for the sheaths of mining wires and cables, marine wires and cables, high-voltage wires and cables, and electrical wire and cable rubber compounds. Fillers. In wire and cable compounds containing chlorine-containing rubber, such as CR, chlorinated polyethylene rubber (CM) and chlorinated butadiene rubber as the main material, calcium carbonate not only functions as a reinforcing filler, but also reduces the It is acidic and absorbs hydrogen chloride generated during rubber processing, thereby avoiding vulcanization delay and reversion of the rubber and improving the extrusion performance of the rubber.

5) Rubber roller: Light calcium carbonate is mainly used in rubber rollers. Light calcium carbonate mainly serves to reinforce, fill and improve the self-adhesion of the rubber roller.

6) Others: Calcium carbonate is also used as a reinforcing filler for tapes and sealing, shock-absorbing, medical and other rubber products, a desiccant for sponge products, and a modifier for latex products.

2. The important role of calcium carbonate in plastics

In addition to synthetic resin as the basic raw material in the plastic processing process, the scientific, correct and reasonable use of various additives and auxiliaries is beyond reproach, among which inorganic powder materials are one of the most important additives. Calcium carbonate (including heavy calcium and light calcium) is the most widely used and consumed inorganic powder material. Calcium carbonate accounts for more than 70% of the total amount of inorganic powder materials used.

3. Application in medicine

Calcium carbonate preparations can participate in the formation of bones and the reconstruction of bone tissue after fractures, as well as muscle contraction, nerve transmission, coagulation mechanism, and reduce the permeability of capillaries. It is used for the prevention and treatment of calcium deficiency, such as osteoporosis, tetany, bone hypoplasia, rickets, and calcium supplementation for children, pregnant women, lactating women, menopausal women, and the elderly with boron trifluoride tetrahydrofuran complex. Calcium carbonate should not be used in combination with digitalis drugs. Drinking large amounts of alcoholic and caffeinated beverages and smoking a lot can inhibit calcium absorption. Eating large amounts of fiber-rich foods can inhibit calcium absorption because calcium combines with fiber to form compounds that are difficult to absorb. This product is used together with phenytoin and tetracyclines, and the absorption of both is reduced. Vitamin D, birth control pills, and estrogen can increase calcium absorption. When aluminum-containing antacids are taken together with this product, the absorption of aluminum will increase. When this product is combined with thiazide diuretics, hypercalcemia is likely to occur (due to increased renal tubular reabsorption of calcium). When this product is combined with potassium-containing drugs, attention should be paid to the occurrence of arrhythmia.

What are the applications of calcium carbonate [Preparation]

Utilizing phosphogypsum desulfurization calcium slag resources, spherical light carbonic acid was synthesized from phosphogypsum desulfurization calcium slag as raw material. The specific steps are as follows:

1) Ammonium chloride leaching: weigh 10g of phosphogypsum desulfurization calcium slag and place it in a 500mL beaker,

Add a certain amount of water so that the liquid-solid mass ratio of water to calcium slag is (6~10):1, then add a certain amount of ammonium chloride solid, and place it in a constant temperature water bath for full leaching for 180 minutes , the leached suspension is allowed to stand at room temperature, and then filtered with suction. The filtrate is the refined CaCl₂ solution, which is carbonized for later use, and the filter residue is dried and weighed.

2) Preparation of light calcium carbonate by carbonization: transfer the above refined CaCl₂ solution into a three-necked flask and pass in

CO₂ Carry out carbonization, control the carbonization temperature to 40°C, and the CO2 flow rate to 40mL/min. When the pH value of the solution reaches 6.5~7.0, the carbonization end point is reached and the reaction is stopped. Filter the carbonized precipitate, take the filter residue and dry it at 120°C for 2 hours to obtain a light calcium carbonate product.

What are the applications of calcium carbonate [Main reference materials]

[1] Encyclopedia of Chinese Middle School Teaching·Chemistry Volume

[2] Xu Bo, Zhou Jianlie. Research progress on calcium carbonate supplement preparations[J]. Chinese Journal of Clinical Nutrition, 2000, 8(3): 198-200.

[3] Song Long, Zhang Ying, Li Shuying, et al. Research progress on calcium carbonate effervescent preparations[J]. Journal of Beijing Union University: Natural Science Edition, 2018, 32(2): 36-39.

[4] Huang Jiaming, Genan. Application and research progress of calcium carbonate in my country’s rubber industry [J]. Rubber Industry, 2006, 53(10): 625-630.

[5] Quantitative analysis of natural medicinal ingredients

[6] Liu Yingjun. Progress in the application of calcium carbonate in plastics[J]. Inorganic Salt Industry, 2008, 40(3): 11-13.

[7] Calcium Carbonate Tablets Instructions

[8] Shi Ting, Wang Xingang, Wu Jianfeng, et al. Preparation of light calcium carbonate from phosphogypsum desulfurization calcium slag [J]. Progress in Chemical Industry, 2015, 34(1): 178-182.

Calcium Carbonate Tablets Instructions

[8] Shi Ting, Wang Xingang, Wu Jianfeng, et al. Preparation of light calcium carbonate from phosphogypsum desulfurization calcium slag [J]. Progress in Chemical Industry, 2015, 34(1): 178-182.