Calcium Carbonate
WHAT IS CALCIUM CARBONATE?
PRODUCTION METHOD, APPLICATION AND CHARACTERISTICS OF LIME
Calcium carbonate is a chemical compound with the formula CaCO3. It is commonly found as minerals in some rocks of the Earth’s crust, such as calcite and aragonite (especially limestone, which is a type of sedimentary rock composed mainly of calcite). Calcium carbonate is a major component in sea pearls and the shells of sea creatures, snails and eggs of egg-laying animals. Calcium carbonate is a constituent of agricultural lime and is formed when calcium ions in hard water react with carbonate ions. This substance is used to prepare stomach medicines. It is used as a raw material for the production of calcium supplements or antacid drugs, but consuming too much of it can be dangerous and cause improper digestion.
A LOOK AT THE HISTORY OF CALCIUM CARBONATE
Calcium carbonate has been used since 40,000 BC until today. The history of calcium carbonate shows how mankind has been able to take advantage of the unique properties of this mineral in various applications. From prehistoric paintings on the walls of caves to today’s modern industrial production in the production of products such as paper and plastic, they are all signs of the evolution of calcium carbonate applications. The “Anglo-Saxons” used a lot of calcium carbonate or chalk, literally “white powder”, and this is exactly what has been used for thousands of years; This compound has been used as a white pigment in the production of colors, the initiator of reactions and the production of plaster. These tribes extracted and processed chalk, which is a form of Limestone, from the nearby beaches. They found that the soft ore could be easily mined with simple tools such as saws and axes. In addition, it was usually necessary to crush and fragment the gypsum to turn it into a quality powder. To this day, gypsum is still one of the forms of calcium carbonate found in the earth’s crust, which is used in the form of important stones, including limestone and marble, in a wide range of products in people’s daily lives. Calcium carbonate is one of the most widely used raw materials in the world and its new applications are constantly being developed. According to this explanation, its use is expected to grow well in the next millennia.
CALCIUM CARBONATE PRODUCTION METHODS
Most of the calcium carbonate used in industry is obtained by industrial extraction or extraction from mines. Pure calcium carbonate (such as food or pharmaceutical) can be extracted and produced from a pure source (usually marble). Also, CaCO3 can be prepared from calcium oxide. For this process, water is added to calcium oxide to form calcium hydroxide. Then carbon dioxide passes through this solution to precipitate the desired CaCO3. This compound is known in the industry as precipitated calcium carbonate (PCC):
CaO + H2O → Ca(OH)2
Ca(OH)2 + CO2 → CaCO3 ↓ + H2O
PROPERTIES AND APPLICATIONS OF CALCIUM CARBONATE
Mineral calcium carbonate has the same general properties as other carbonates. Its significant volume reacts with acids and releases carbon dioxide:
CaCO3(s) + 2H + (aq) → Ca2 + (aq) + CO2 (g) + H2O (l)
When the solution is heated, it releases carbon dioxide, which is called a thermal decomposition reaction or calcination (= in the case of CaCO3 it is up to 840 °C).
The formation of calcium oxide, which is usually called burnt lime, with a reaction enthalpy of 178 kJ/mol, occurs according to the following reaction:
CaCO3 → CaO + CO2
Calcium carbonate reacts with water saturated with carbon dioxide to form soluble calcium bicarbonate:
CaCO3 (s) + CO2 (g) + H2O (l) → Ca (HCO3)2 (aq)
This reaction is very important in the erosion of carbonate rock and the formation of caves, and leads to the formation of hard water (containing very large amounts of calcium ions) in many areas. The unusual form of this material is the hexahydrate, ikaite with the molecular formula CaCO3.6H2O. Icaite is only stable at 8 degrees Celsius.
APPLICATIONS OF CALCIUM CARBONATE
Calcium carbonate is found naturally in rock formations and some mineral resources. (Four percent of the earth’s crust is made of this material.) This substance is slightly soluble in water, and for this reason, it is washed in natural water systems, and as a result, it will cause hardness in water resources. Limestone and gypsum are composed of calcium carbonate; Like what we know in coral reefs. This mineral is usually prepared through extraction from mines or extraction and purification in industry. CaCO3 occurs as limestone, gypsum, and dolomite and usually contains impurities such as clay. Limestone is well known as a raw material in many industries. The most important industries in which this combination is used are as follows:
- Provision of health and personal care products
- Oil production
- Plastic and rubber industries
- cement industry
- glass making
- Steel industries
- paper making
- Application in construction industry
1- AGRICULTURE AND HORTICULTURE
Calcium carbonate is the most important ingredient in horticultural lime (commonly called agricultural lime) used to regulate soil acidity. The addition of CaCO3 also improves soil quality for plant life. Limestone has many advantages for gardening and agriculture, which you can see in the following section:
- A healthy source of calcium for plant nutrition and growth
- PH regulating properties
- Increasing the ability of acidic soils to hold water
- Helping plants better absorb important nutrients, including nitrogen
2- CEMENT CONSTRUCTION AND PRODUCTION
Do you know that the ground you walk on in the streets and alleys every day is calcium carbonate? Calcium carbonate (CaCO3) is a major ingredient in the construction industry, mainly used in the production of cement. This material is usually used for these purposes in a lime state. In addition to cement structures, CaCO3 is highly considered in the foundation of road construction projects. This material is used to help improve the texture of the soil and allows bridge building, house construction and fortification projects to be completed well. Larger lumps of this material are usually used to produce and meet the need for aggregates. Lime reacts with cement preparation additives, turns into clay cement and creates harder compounds. In addition, the strength and hardness of materials produced with CaCO3 allows large and heavy construction vehicles to easily pass through construction sites. With the introduction of this material to the cement production industry, the main form used in these processes is limestone. Cement is basically composed of calcium silicates and calcium sulfate.
3- COMBATING ACID RAIN IS USED IN AQUATIC ECOSYSTEMS
Studies show that calcium carbonate helps reduce the damaging effects of acid rain in all aquatic river ecosystems. Currently, the United States treats acidic waterways by sprinkling a powder of this substance to neutralize harmful acids in this way. Scandinavian countries and Scotland also use CaCO3 in this way. Limestone sediments are used to treat barren areas around damaged lakes. Consider limestone as a common protector; Because it can neutralize the amount of acidity that may have been washed into the surrounding soil.
4- ADD TO LIVESTOCK AND POULTRY FEED
It is a known principle that living organisms need calcium carbonate to have bones and teeth. Do you know that your teeth and bones are made of a certain amount of calcium carbonate? Likewise, plants and animals also use this mineral to build their skeletons and shells. The animals that are more interested in this regard include snails, corals, pearls, turtles and other crustaceans. CaCO3 is re-deposited to the soil with the death of plants and animals. Apart from these, egg-laying animals somehow need to use this calcareous compound a lot to have harder shells in their eggs. Therefore, if you hear the name of animal Limestone, it means that it can be added to poultry feed. This compound is added to livestock and poultry feed to provide them with this nutrient.
PACKAGING OF CALCIUM CARBONATE
Calcium Carbonate Packaging Calcium carbonate packaging is usually available in woven bags of the finest polymer fibers. These bags are marketed according to the standards of the manufacturing factory. 25 kg, 1000 kg, jumbo bag, shrink pack, or bulk shipping are available for granular calcium carbonate powder.
SAFETY OF CALCIUM CARBONATE
CaCO3 is a white solid compound. Contact of this substance with skin and eyes causes burning and irritation. Breathing the dust of this solid substance, especially in powder form, can irritate the respiratory system.
The adverse effects of this compound are for the eyes, skin and respiratory organs, so it is recommended that workers must use gloves, glasses, masks and special work clothes to work with this substance in the industry.
Consuming large amounts of this substance may irritate the digestive system. Although the risk of swallowing is less, if it is accidentally eaten, the person must be taken to the doctor immediately.
*Chemical stability: CaCO3 is stable at normal temperatures and pressures. Contact of CaCO3 with air dust and moisture should be avoided.
* Incompatibility with other materials: This compound is incompatible with strong oxidizing agents, acids, aluminum, magnesium, fluorine.
*Dangerous products of calcium carbonate decomposition: carbon monoxide, carbon dioxide, calcium oxide.
*Dangerous polymerization: does not occur.
STORAGE CONDITIONS OF CALCIUM CARBONATE
Packages containing calcium carbonate should be stored in well-ventilated warehouses. Try to minimize the generation and accumulation of dust caused by CaCO3 powder or lumps. CaCO3 bags should be stored in a dry and cool place. The lid of containers, containers or bags must be tightly closed.
RELATED INDUSTRIES FOR CALCIUM CARBONATE
1-Mineral aragonite: One of the compounds that we mentioned earlier in the above sections and is somehow related to the calcium carbonate compound is aragonite. Aragonite is a carbonate mineral and is one of the three common crystalline forms of Limestone (other forms of this mineral are “calcite” and “vaterite“). Aragonite is formed by biological and physical processes including sedimentation in marine and freshwater environments. The difference between calcite and aragonite is actually in their crystal lattice. There is an orthorhombic crystal system, a quasi-hexagonal structure for these compounds. Aragonite may have a columnar structure. This mineral structure can be very variable in different places. The mineral aragonite is thermodynamically unstable at standard temperature and pressure. Aragonite gradually changes to calcite over 10 million to 100 million years. According to the conditions of formation of this mineral, different types can be introduced for it; Golden aragonite, cauliflower aragonite, needle aragonite, gem aragonite are the most common stones of this mineral sample. The industrial application of aragonite ore is to remove pollutants such as zinc, cobalt and lead from polluted wastewater. The price of aragonite stone is generally expensive. This stone is very well known in the jewelry industry.
2- Limestone: Scientific limestone is introduced as Limestone. This stone is a sedimentary stone and is extracted directly from mines. All of us are more or less familiar with construction limestone. There are two forms of building lime, quicklime and quicklime. From the combination of quicklime with water, quicklime is obtained, which is calcium hydroxide. Limestone of Isfahan is the best and most famous mine for this mineral. The price of limestone is determined according to the geographical location of the mine, the stages of extraction, transportation, global prices, etc. Limestone is a sedimentary rock. If these stones are subjected to the pressure and internal heat of the earth, they will turn into metamorphic stones such as marble.
TEHCNICAL DATA SHEET OF CALCIUM CARBONATE
| NO | Requirements | unit | Standard Specification |
|---|---|---|---|
| 1 | Specific Gravity | 𝑔𝑟/𝑐𝑚3 | ２.７Min |
| 2 | Color | - | White |
| 3 | Insoluble in 15% Hcl | % | ２Max |
| 4 | Residue on ASTM sieve No:２００(wet method) | Wt% | 3 Max |
| 5 | method) Residue on ASTM sieve No:３２５(wet method) | Wt% | 10±５ |
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