QUANTUM AND STATISTICAL REPORT A Project Report on Study of Calcium Carbonate [CaCO3] By: Bhavya Shah I031 Aman Sohail I034 Manas Patel I037 Department of MBA Tech (Information Technology) Mukesh Patel School of Technology Management & Engineering April 2022 STUDY OF CALCIUM CARBONATE 1 QUANTUM AND STATISTICAL REPORT TABLE OF CONTENTS 1. Introduction ............................................................................... 3 1.1 Nomenclature .......................................................................... 3 2. Types of Calcium Carbonate .................................................... 4 2.1 Calcite ..................................................................................... 4 2.2 Aragonite ................................................................................. 5 2.3 Dolomite.................................................................................. 6 3. Elemental Analysis ................................................................... 7 3.1 Occurrence .............................................................................. 7 3.2 Appearance.............................................................................. 8 3.3 Structure .................................................................................. 8 4. Preparation ................................................................................ 9 4.1 Existence in Nature ................................................................. 9 4.2 Preparation of crystalline form ............................................... 9 4.3 Preparation of amorphous form .............................................. 10 5. Factors affecting Preparation .................................................... 10 5.1 temperature.............................................................................. 10 5.2 pH and Pressure ...................................................................... 11 5.3 Calcium and carbonate ion concentration ............................... 12 6. Properties .................................................................................. 12 6.1 Physical Properties .................................................................. 12 6.2 Chemical Properties ................................................................ 13 7. Uses and applications ................................................................ 13 8. Future aspects of calcium carbonate ......................................... 14 9. Reference................................................................................... 16 STUDY OF CALCIUM CARBONATE 2 QUANTUM AND STATISTICAL REPORT 1. Introduction Calcium carbonate, or CaCO3, comprises more than 4% of the earth’s crust and is found throughout the world. It’s most common natural forms are chalk, limestone, and marble, produced by the sedimentation of the shells of small fossilized snails, shellfish, and coral over millions of years. Although all three forms are identical in chemical terms, they differ in many other respects, including purity, whiteness, thickness and homogeneity. Calcium carbonate is one of the most useful and versatile materials known to man. Many of us encounter calcium carbonate for the first time in the school classroom, where we use blackboard chalk. Chalk has been used as a writing tool for over 10,000 years and is a fine, microcrystalline material. As limestone, calcium carbonate is a biogenic rock, and is more compacted than chalk. As marble, calcium carbonate is a coarsecrystalline, metamorphic rock, which is formed when chalk or limestone is recrystallized under conditions of high temperature and pressure. Large deposits of marble are found in North America and in Europe; e.g., in Carrara, Italy, the home of the pure white "statuario" from which Michelangelo created his sculptures. Calcium carbonate, as it is used for industrial purposes, is extracted by mining or quarrying. Pure calcium carbonate can be produced from marble, or it can be prepared by passing carbon dioxide into a solution of calcium hydroxide. In later case calcium carbonate is derived from the mixture, forming a grade of product called "precipitated calcium carbonate,” or PCC. PCC has a very fine and controlled particle size, on the order of 2 microns in diameter, particularly useful in production of paper. The other primary type of industrial product is "ground calcium carbonate,” or GCC. GCC, as the name implies, involves crushing and processing limestone to create a powdery-like form graded by size and other properties for many different industrial and pharmaceutical applications. A study of calcium carbonate provides important lessons about the history of the earth, since chalk, limestone and marble trace their origin to shallow water. Thus, observation that large amounts of chalk deposits of the same age are found on many continents led to the discovery that there existed a period in which there was shallow water world-wide where shelled organisms thrived. Some offer this as proof for the Biblical flood. 1.1 Nomenclature 1.1.1 Nonproprietary Names Recommended international nonproprietary name is termed as Calcium Carbonate. Synonyms: E 170, calcite, aragonite, vaterite, chalk, CI pigment white 18, drop chalk, whiting, English white, Paris white. 1.1.2 Proprietary Names Caltrate (Pfizer Consumer Healthcare), Maalox Quick Dissolve (Novartis Consumer Healthcare), Maalox Regular Strength (Novartis Consumer Healthcare), Os-Cal, Alka-Seltzer, Alcalak (Medique Products), Oyster Shell Calcium (Swanson Health STUDY OF CALCIUM CARBONATE 3 QUANTUM AND STATISTICAL REPORT Products), Oysco, Cal-Gest (Rugby), Icar Prenatal Chewable Calcium (Hawthorn Pharmaceuticals), Oyster Shell Calcium, Children’s Pepto, Rolaids Soft Chew, Adcal 1500 Chewable (Biokirch), Ostocal, Calcichew, Calcichew 500 mg purutabletti, Calcichew Spearmint 500 mg purutabletti, Calcimagon 500 mg, Calcioral, astical, Calcitugg, Boots. 2. Types of Calcium Carbonate 2.1 Calcite Calcite is a rock-forming mineral with a chemical formula of CaCO3. It is extremely common and found throughout the world in sedimentary, metamorphic, and igneous rocks. The most common form of calcium carbonate, calcite is known for the variety and beautiful development of its crystals. These occur most often as scalenohedra and are commonly twinned, sometimes forming heart-shaped, butterfly twins. Crystals with rhombohedra terminations are also common; those with shallow rhombohedral terminations are called nail head spar. Highly transparent calcite is called optical spar. Although calcite can form spectacular crystals, it is usually massive, occurring either as marble (p.301) or as limestone (p.319). It is also found as fibers, nodules, stalactites, and earthy aggregates. Calcite specimens can occur in metamorphic deposits, igneous rocks, and hydrothermal veins. Some geologists consider it to be a “ubiquitous mineral” – one that is found everywhere. Calcite is the principal constituent of limestone and marble. These rocks are extremely common and make up a significant portion of Earth’s crust. The properties of calcite make it one of the most widely used minerals. It is used as a construction material, abrasive, agricultural soil treatment, construction aggregate, pigment, pharmaceutical and more. The composition of calcite is, CaC03. CaO = 56.0 per cent, C02 = 44.0 per cent. Small amounts of magnesium, ferrous iron, manganese, and zinc may replace the calcium. The diagnostic feature are its softness, its perfect cleavage, light color, vitreous luster. Distinguished from dolomite by the fact that fragments of calcite effervesce freely in cold hydrochloric acid, whereas those of dolomite do not. Distinguished from aragonite by having lower specific gravity and rhombohedral cleavage. Figure 1 Structure of Calcite STUDY OF CALCIUM CARBONATE 4 QUANTUM AND STATISTICAL REPORT Calcite most commonly occurs in sedimentary settings, particularly in shallow marine settings as the shells and hard parts of marine organisms. It is also found in hydrothermal veins and hot spring deposits. In sedimentary environments, calcite most often occurs as limestone rock or as marble, which is metamorphosed limestone. Calcite is often the only mineral present, but in some sedimentary environments, calcite may be associated with dolomite, gypsum, anhydrite, chert, or halite. In hydrothermal veins, quartz and other common vein minerals such as pyrite, dolomite, fluorite, galena, and chalcopyrite may occur with calcite (Kauwenbergh, 2010). 2.1.1 Geological Importance All natural waters contain dissolved calcium and carbon dioxide, and their concentration is especially high in seawater. Many marine animals including corals, snails, clams, algae, and microscopic plankton use calcite and aragonite to form their shells and hard parts. Microorganisms can also indirectly lead to the precipitation of calcite as they alter the chemistry of the fluids in which they live. Once formed, calcite is easily dissolved and its component ions released to precipitate elsewhere. As a consequence, calcite is not only the main mineral of limestone rocks and marble (metamorphosed limestone), but also a common accessory component of sandstone and siltstone rocks. 2.1.2 Distribution Countries of origin for calcite are almost every continent. Large deposits of brightly colored calcites occur in Mexico and the USA. Calcite is distributed in the following places: Iceland -Helgustadanama mine, Reydarfjord. England – From Alston Moor, Egremont, and Frizington, Cumbria; Weardale, Durham; at Liskeard, Cornwall, Germany – From St. Andreasberg, Harz Mountains, and Freiberg, Saxony, Namibia – From Tsumeb, Congo – Mupine mine, Katanga Province, Romania – At Herja (Kisbanya), Baia Mare (Nagybanya) district, Russia – At Dalnegorsk, Primorskiy Krai. 2.2 Aragonite Aragonite is a carbonate mineral and its formula is calcium carbonate. It has the same formula as Calcite and Vaterite, but has a different crystal structure. They are tabular, prismatic or needle-like, often with steep pyramidal or chisel-shaped ends, and can form columnar or spreading aggregates. Multiple twin crystals that appear hexagonal in shape are common. Although aragonite sometimes resembles calcite, it is easily distinguished by the absence of rhombic cleavage. Samples can be white, colorless, gray, yellowish, green, blue, reddish, purple or brown. Aragonite is found in oxidized areas of ore deposits and in evaporates, hot spring deposits and caves. It is also found in some metamorphic and igneous rocks and is formed by biological and physical processes, STUDY OF CALCIUM CARBONATE 5 QUANTUM AND STATISTICAL REPORT including precipitation from marine and freshwater environments. Its first noted occurrence was in Aragon region of Spain. 2.2.1 Occurrence It turns into calcite over geological time. Primary sediment in warm marine waters such as oolites and carbonate mud, an essential clastic sedimentary component as the hard parts of the shells and skeletons of many marine micro-organisms; also from evaporite deposits; in sinter in hot springs and in stalactite in caves; characteristic of high pressure, low temperature (blueschist facies) metamorphism; as amygdullary in basalt and andesite; It is a secondary component in altered ultramafic rocks. Aragonite is a high pressure polymorph of calcium carbonate. Therefore, it occurs in high pressure metamorphic rocks such as those formed in subduction zones. Aragonite is metastable at low pressures near the Earth’s surface and is therefore often replaced by calcite in fossils. Aragonite older than the Carboniferous is essentially unknown. It can also be synthesized by adding a solution of calcium chloride in water-ethanol mixtures at ambient temperatures or to a sodium carbonate solution at temperatures above 60 °C (140 °F). 2.2.2 Distribution Many localities, but fine crystals are uncommon. From Molina, Guadalajara Province, Spain. Fine crystals from Racalmuto, Cianciana, and Agrigento, Sicily, Italy. At Dogn´acska and Spania Dolina (Herrengrund), Slovakia. From Tarnowitz, Silesia, Poland. At ˇ the Erzberg, near Eisenerz, Styria, and from Leogang, Salzburg, Austria. On the Spitzberg, Hoˇrenz, near B´ılina, Czech Republic. From Frizington and Cleator Moor, Cumbria, England. Fine examples at the Touissit mine, near Oujda, and from Tazouta, near Sefrou, Morocco. Large crystals from Tsumeb, Namibia. In the USA, in caves at Bisbee, Cochise Co., Arizona; large crystals from near Lake Arthur, Chavez Co., also near Santa Rosa, Guadalupe Co., New Mexico; in the Passaic mine, Sterling Hill, Ogdensburg, Sussex Co., New Jersey. 2.3 Dolomite Dolomite is an important rock-forming mineral that named is French mineralogist Déodat Grated de Dolomieu. It is a colorless to white, pale brown, grayish, reddish, or pink mineral. Its crystals are commonly rhombohedral or tabular, often have curved faces, and sometimes cluster in saddleshaped aggregates. Dolomite may be striated horizontally and twinned. Some crystals may be up to 2 in (5 cm) long. It can also be coarse to fine granular, massive, and, rarely, fibrous. Dolomite is the main constituent in dolomite rocks and dolomitic marbles. It occurs as a replacement deposit in limestone affected by magnesium-bearing solutions, in talc schists, and in other magnesium-rich metamorphic rocks. Dolomite is found in hydrothermal veins associated with lead, zinc, and copper ores. It is also found in altered, silica-poor STUDY OF CALCIUM CARBONATE 6 QUANTUM AND STATISTICAL REPORT igneous rocks, in some carbonatites, and in serpentinites. Crystals of dolomite frequently form in cavities in limestone and marble. In the Vuoriyarvi carbonatite complex, Kola Peninsula, Russia. Fine crystals from Brumado, Bahia, and in the Morro Velho gold mine, Nova Lima, Minas Gerais, Brazil. At Naica, Chihuahua, Mexico. In the USA, in New York, from Lockport, Niagara Co., eastward to Walworth, Wayne Co.; at Stony Point, Alexander Co., North Carolina; in the Mississippi Valley region, in the Tri-State district, at Joplin, Jasper Co., Missouri; Galena, Cherokee Co., Kansas; and Picher, Ottawa Co., Oklahoma. 3. Elemental Analysis Figure 2 Structure of Dolomite 2.3.1 Occurrence Formed by diagenesis or hydrothermal metasomatism of limestone; a primary phase in hypersaline sedimentary environments; a major component of some contact metamorphic rocks and marbles; a gangue in hydrothermal veins; in carbonatites and ultramafic rocks. 2.3.2 Distribution A major rock-forming mineral, abundant worldwide with numerous commercial uses. Some localities for fine examples include: In Italy, from Traversella and Brosso, Piedmont. Exceptional crystals from Eugui, Navarra Province, Spain. At Trieben and Hall, Tirol, Austria. From Freiberg and Schneeberg, Saxony, Germany. At Lengenbach, Binntal, Switzerland. From Trepca, Serbia, Yugoslavia. At Frizington, Cumbria, England. The IUPAC name is Calcium Carbonate, which is also known as names like aragonite, calcite, chalk, limestone, and marble, pearl. The chemical formula of calcium carbonate is CaCO3 with molar mass of 100.08 g/mol. 3.1 Occurrence 3.1.1 Biological Source Eggshells, snail shells and most seashells are predominantly calcium carbonate and can be used as industrial sources of that chemical. Oyster shells have enjoyed recent recognition as a source of dietary calcium, but are also a practical industrial source. Dark green vegetables such as broccoli and kale contain dietary significant amounts of calcium carbonate, but they are not practical as an industrial source. 3.1.2 Geological source Calcite, aragonite and vaterite are pure calcium carbonate minerals. Industrially STUDY OF CALCIUM CARBONATE 7 QUANTUM AND STATISTICAL REPORT important source rocks which are predominantly calcium carbonate include limestone, chalk, marble and traverti ne. 3.1.3 Extraterrestrial Beyond Earth, strong evidence suggests the presence of calcium carbonate on Mars. Signs of calcium carbonate have been detected at more than one location (notably at Gusev and Huygens craters). This provides some evidence for the past presence of liquid water. occurring as the mineral vaterite. The aragonite form can be prepared by precipitation at temperatures above 85 °C; the vaterite form can be prepared by precipitation at 60 °C. Calcite contains calcium atoms coordinated by six oxygen atoms; in aragonite they are coordinated by nine oxygen atoms. The vaterite structure is not fully understood. Magnesium carbonate (MgCO3) has the calcite structure, whereas strontium carbonate and barium carbonate (SrCO3 and BaCO3) adopt the aragonite structure, reflecting their larger ionic radii. 3.2 Appearance According to the United States Pharmacopeia (USP), CaCO3 is fine, white, Odorless, tasteless, and microcrystalline powder, while it is described as a white or almost white powder in the European Pharmacopeia (Eur. Ph.). Figure 4 Calcium Carbonate Figure 3 Molecular Structure of Calcium Carbonate 3.3 Structure The thermodynamically stable form of CaCO3 under normal conditions is hexagonal βCaCO3 (the mineral calcite). Other forms can be prepared, the denser (2.83 g/cm3) orthorhombic λ-CaCO3 (the mineral aragonite) and hexagonal μ-CaCO3, Figure 5 Ionic Structure of Calcium Carbonate STUDY OF CALCIUM CARBONATE 8 QUANTUM AND STATISTICAL REPORT 4. Preparation 4.1 Existence in nature CaCO3 is one of the most abundant materials found in earth’s crust and forms the rock types like limestone and chalk. Moreover, it is the most abundant chemical sediment in modern and most ancient oceans, making up roughly 10% of sediments. CaCO3 can be a dominant sedimentary constituent in virtually any environment, at any latitude, and in any depth of water. On the other hand, carbonates are forming extensively in many regions in the western margins of large oceans, in both the southern and northern hemispheres, at seawater temperatures ranging from about _2 to 40°C. Nearly all the CaCO3 that makes up carbonate platforms is derived from marine organisms. CaCO3 is also an important component in biological systems, such as shells of marine organisms, pearls, and egg shells. Some of these systems, Eg, Oyster shells, have enjoyed recent recognition as a source of dietary Ca, but are also a practical industrial source. While not practical as an industrial source, dark green vegetables such as Broccoli and Kale contain dietary significant amounts of CaCO3. Carbonates are largely made up of skeletal remains and other biological constituents that include fecal pellets, lime mud (skeletal), and microbial mediated cements and lime muds. 4.2 Preparation of crystalline form CaCO3, upon precipitation, is capable of forming an amorphous phase comprising colloidal systems of amorphous primary particles. The colloidal stability of these systems is not sufficient to prevent aggregation. Due to the high number density of primary particles and the high ionic strength of the solution, the aggregation process leads to a gelation of the reaction mixtures. The gel is bound by van der Waals forces only. Therefore, the gel is colloid less stable and undergoes a quick morphological collapse. The recrystallization to vaterite or calcite takes place simultaneously with the dissolution of the gel. The sequence of reactants directly affects the morphological structure of CaCO3 upon precipitation. For example, if Na2CO3 solution is first introduced into the reactor and then CaCl2 solution is fed to this solution under standard conditions, the product consists almost entirely of vaterite. The increase in particle size is due to spherulitic growth mechanism of vaterite caused by multiple passages of the particle through the region of maximum supersaturating at the feed inlet. For the reversed sequence case a larger percentage of calcite. The calcite cubes are aggregated to form larger irregular particles and are partly overgrown by clusters of vaterite. This may be due to the same mechanism as in the standard experiment (first case), with the vaterite nucleating on the Calcite surface. When MgCl2 is introduced into CaCl2 solution to avoid premature precipitation, some calcites are formed but all the particles are mainly vaterite. The vaterite particles of various shapes are aggregated and of various shapes. When KOH is introduced into Na2CO3 solution for the same purpose, large calcite particles and smaller aragonite needles, which are attached to the calcite cubes, are formed. STUDY OF CALCIUM CARBONATE 9 QUANTUM AND STATISTICAL REPORT 4.2.1 Calcium Dioxide acetate and Carbon The hierarchical monodispersed aragonite microspheres can be prepared by carbonating Ca(CH3COO)2 aqueous solution with CO2 gas at a high pressure 40 bar and a high temperature of 80°C after 60 min of reaction. Ca(CH3COO)2 aqueous solution is introduced into a reactor under atmospheric pressure. Pure CO2 gas is then continuously introduced until it reaches the setting pressure. During the experiments, the CO2 pressure in the reactor is kept constant by continuous supplying of CO2 from the cylinder using a pressure controller. After a given time, the stirring is stopped. The obtained precipitates are collected from the man-made filter and washed several times with water as well as anhydrous ethanol then air dried. The reaction between CO2 and Ca(CH3COO)2 in an aqueous solution was first proposed by Kakizawa et al. For the fixation of the greenhouse gas CO2 into solid CaCO3. Generally, CaCO3 can be dissolved in a CH3COOH solution at atmosphere conditions. Therefore, CH3COOH is replaced by H2CO3 in this carbonation crystallization process, resulting in precipitating CaCO3 particles. Moreover, it is reported that the reaction between CO2 and Ca(CH3COO)2 is endothermic and occurs spontaneously at temperatures above 45°C at an atmospheric pressure. 4.2.2 Quicklime or Hydrated Lime Limestone is converted to CaO by heat, followed by formation of milk of lime (Ca(OH)2) either by slaking quicklime or by dispersing hydrated lime in water. Finally, Ca(OH)2 is combined with CO2 to form precipitated CaCO3. 4.3 Preparation of Amorphous form 4.3.1 Calcium Chloride and Sodium Carbonate CaCl2 and Na2CO3 solutions, equimolar in Ca and carbonate ions, are rapidly mixed. For example, 106 mg of solid Na2CO3 is added to 20 mL of a 0.5 M NaOH solution and 30 mL of water. This solution is combined with 50 mL of a 20 mM CaCl2 solution and stirred rapidly, followed immediately by vacuum filtration and rinsing with acetone to dry the solid. 4.3.2 Calcium Hydroxide and Carbon Dioxide Precipitates of pure amorphous CaCO3 can be obtained by bubbling CO2 through a saturated Ca(OH)2 solution at 0°C. The precipitation is stopped when the pH reaches 8 and the precipitate is filtered and rinsed with cold acetone. The precipitate dried under high vacuum at 0°C for 36 h and stored under phosphorous pentoxide in a desiccator. Ikaite (CaCO3.6H2O) is prepared in the same way as the amorphous, but the precipitate is not dried in a vacuum after washing with acetone, instead, it is immediately placed in a freezer at 20°C. 5. Factors affecting preparation 5.1 Temperature The influence of temperature on CaCO3 polymorph formed from (NH4)2CO3– Ca(CH3COO)2 system was investigated. At 25 and 80°C, the predominant form was STUDY OF CALCIUM CARBONATE 10 QUANTUM AND STATISTICAL REPORT found to be vaterite, while calcite form was obtained at 50°C. Less than 5% aragonite was observed at 70°C. In CaCl2–Na2CO3 system, vaterite with specific morphologies was formed at 2–35°C, whereas needleshaped aragonite crystals were obtained at 50–70°C. Figure 6 Temperature v/s Calcium ion 5.2 ph and Pressure The effect of pH on the polymorphic phase and crystal growth upon precipitation of CaCO3 was investigated by using gas diffusion method. At pH 0.5, calcite and aragonite crystals are obtained. When the pH value was higher than 5.5, the precipitates are calcite crystals with different morphologies and particle sizes. It was also reported that calcite precipitation in water was favored in alkaline conditions. Han et al. also reported that higher pH value tended to induce calcite crystals. Cheng et al. and Yu et al. also reported that greater morphology control can be afforded by low supersaturation as pH is decreased. This means that the induction time of CaCO3 precipitation increases considerably with decreasing pH. The effect of pressure on transition of calcite forms was first studied by Bridgman. It was observed a transition to a slightly denser phase (calcite II) at 1.44 GPA and a transition to a significantly denser phase (calcite III) at 1.77 GPA. Singh and Kennedy and Merrill and Bassett placed the calcite I–calcite II transformation at 1.45 and 1.5 GPA and the calcite II–III transformation at 1.74 and 2.2 GPA, respectively. Moreover, the phase transition of metastable calcite III–post calcite III initiates at a pressure of 15.5 GPA and is completed between 25 and 30 GPA. In addition to the aforementioned calcite form, there exists a denser calcite VI form that can be formed using shock compression experiments. The phase diagram of calcite is further complicated by the appearance of the calcite II and calcite III intermediates at highpressure phases in the range from 1.0 to 2.5 GPA. At higher pressures, calcite is known to undergo yet another phase transition; this high-pressure phase, known as calcite IV, occurs at pressures in excess of 10 GPA and is usually observed in impact experiments in the form of a somewhat anomalous rarefaction shock. Figure 7 pH v/s Calcium ion None of the intermediate phases of calcite is stable under equilibrium conditions. Karley developed a theoretical model for the STUDY OF CALCIUM CARBONATE 11 QUANTUM AND STATISTICAL REPORT equation of state of CaCO3 that includes phase transitions and melting. As noted, calcite IV is assumed to have the same properties as aragonite except for a shift in the energy. Different CaCO3 phases have been determined by using a combination of advanced ab initio simulation techniques and high-pressure experiment. The crystal structure of post aragonite phase in CaCO3 at a pressure of 40 GPA was identified in addition to a number of energetically competitive structures (stable phase I and metastable phases II–IV). Above 137 GPA, phase I with a pyroxene-type structure with chains of CO4 tetrahedral becomes more stable than post aragonite. 5.3 Calcium and Carbonate Ion concentration The effect of Ca/CO3 concentration ratio on CaCO3 particles size and shape, prepared from CaCl2 and Na2CO3 system, was investigated. It was found that particles’ shape changed from squared, spherical, to oblong by increasing the concentration (g/L) ratio of Ca/CO3 from 0.21 to 1.22. On the other hand, the average particle size changed from 3.5 to 1.8 μm[119,120]. It was explained by formation of soluble complexes Coax (CO3)y at excess CO3 anions, which lowers the supersaturation and, accordingly, the primary nucleation rate. 6. Properties 6.1 Physical Properties Calcium carbonate appears as white, odorless powder or colorless crystals. Practically insoluble in water. Occurs extensive in rocks world-wide. Ground calcium carbonate (CAS: 1317-65-3) results directly from the mining of limestone. The extraction process keeps the carbonate very close to its original state of purity and delivers a finely ground product either in dry or slurry form. Precipitated calcium carbonate (CAS: 47134-1) is produced industrially by the decomposition of limestone to calcium oxide followed by subsequent carbonization or as a by-product of the Solvay process. Precipitated calcium carbonate is purer than ground calcium carbonate and has different handling properties. Limestone (calcium carbonate) that has been recrystallized by metamorphism and is capable of taking a polish. Compound Formula Molecular mass Appearance Melting point Boiling point Density Acidity Refractive index CaCO3 100.09 g/mol White powder 825oC N/A 2.93 g/cm3 9.0 1.59 6.1.1 Optical Property Carbonates can easily be recognized in soil thin sections, as their birefringence is extreme resulting in upper-order creamy white interference colors. They are also characterized by high relief generally from strongly negative to strongly positive depending upon their orientation. 6.1.2 Polymorphism CaCO3 exists naturally in six different forms: three crystalline polymorphs, calcite, aragonite, STUDY OF CALCIUM CARBONATE 12 QUANTUM AND STATISTICAL REPORT and the metastable vaterite; two hydrate phases, monohydrocalcite and ikaite; in addition to amorphous CaCO3. 6.2 Chemical Properties 6.2.1 Ionization Constant Chemical equilibria of CaCO3 in aqueous solution can be described as H2CO3 undergoing dissociation to give H+, HCO3_, and CO3 ionic species. The corresponding dissociation constants pKa1 and pKa2 are 6.35 and 10.32 at 25°C, respectively. However, the presence of Ca ions leads to the formation of CaHCO3+ CaCO3, and CaOH+ in solution with association constants pKCaHCO3+pKCaOH+ , and pKCaCO3 of 1.26, 1.49, and 3.22 at 25°C, respectively. 6.2.2 Solubility Characteristics According to the USP, it is practically insoluble in water. Its solubility in water is increased by the presence of any ammonium salt or of CO2. The presence of any alkali hydroxide reduces its solubility. Figure 8 Solubility v/s pH of Calcium Carbonate It is insoluble in alcohol. It dissolves with effervescence in 1 N CH3COOH, in 3 M HCl, and in 2 M HNO3. The solubility of CaCO3 (conventional) in water is 16.6 mg/L (20°C, pH 9–9.4), while that of the aragonite and calcite forms is 6.6 mg/L (20°C) and 11 mg/L (20°C) for the vaterite form. The amorphous form of CaCO3, with particles predominately in the nanoscale range, is approximately 10 times more soluble than crystalline CaCO3. In general, the solubility of the hydrate forms of CaCO3 was found to be higher than those of anhydrous forms calcite, aragonite, and vaterite. 7. Uses and Application CaCO3 is authorized as a food color in the European Union (EU) under Directive 94/36/EC and is also authorized as an additive generally permitted in foodstuffs under Directive 95/2/EC. It is also included in Directive 2001/15/EC on substances that may be added for specific nutritional purposes in foods for particular nutritional uses, and in Directive 2002/46/EC relating to food supplements, and it can be used in fortified foods according to Regulation 1925/200626 on the addition of vitamins and minerals and of certain other substances in food. CaCO3 has been evaluated by Joint FAO/WHO Expert Committee on Food Additives (JECFA) in 1965, when the Committee established an acceptable daily intake (ADI) not limited. The EU Scientific Committee of Food (SCF) evaluated CaCO3 as part of a group of carbonates and assigned a group ADI not specified. CaCO3 together with other carbonates has also been reviewed by TemaNord, who concluded that there was no need for a reevaluation. The SCF allocated a tolerable upper intake level (UL) for Ca of 2500 mg/person per day STUDY OF CALCIUM CARBONATE 13 QUANTUM AND STATISTICAL REPORT as a nutrient and also established a population reference intake of 700 mg Ca/day (range 400–1200 mg/day depending on age and physiological status). CaCO3 is included in Commission Decision 2006/257, establishing an inventory of ingredients in cosmetic products. In pharmaceuticals, CaCO3 is used as an excipient and as an active ingredient of antacids. It is also included in Directive 91/41428 concerning the placing of plant products on the market. CaCO3 has been registered under the Reach Regulation 1907/2006. CaCO3 is included in the Food and Drug Administration (FDA) list of food additives that are generally recognized as safe (GRAS) for use in nutrient and dietary supplements, and is also certified by the FDA for use in amounts consistent with good manufacturing practice to color drugs generally. CaCO3, both natural and precipitated, is widely used as a major filler in paper, paint, adhesives and sealants, and polymers. Also CaCO3 meets the pharmacopeia requirements as a therapeutic source in antacids, as Ca supplements, and as a tableting excipient. As a pharmaceutical excipient, it is mainly used as diluents, coating agent, and wet binder in solid dosage forms, as a base for medicinal and dental preparations, and as buffering and dissolution aid in dispersible tablets, as well as food additive. CaCO3 is also used as a fire extinguisher foam filler, as an abrasive in household cleaners, as a flux in welding rod coatings, as a diluent in agricultural pesticide dusts, and as a dusting agent in mines, in the manufacture of Portland cement, lime, glass, and metallurgical fluxes. Some applications are listed as below: Paper: Calcium carbonate is added in paper and pulp for filler application. It can also be used as coating pigment. It improves opacity and brightness of paper. Both PCC and GGC are used in the paper-making process. Paints & coatings: Calcium carbonate is used as extender in this application. It helps to densify the final product. It is also used in finishing coats where high gloss is required. Plastics: Calcium carbonate is used as mineral fillers in the plastic sector. Owing to its compatibility with various polymers, easy availability and specific particle size it is widely accepted in the industry. Adhesives & sealants: Calcium carbonate is used as basic raw material in formulations of adhesives and sealants. Various products include tile adhesives and wet-room sealants among others. Others: Calcium carbonate agriculture application, it is used for soil neutralization, mineralization and nitrification. It also helps to improve phosphorus and nitrogen. It is also used in the pharmaceutical sector in tablets or filler applications and purification of iron from iron furnace. 8. Future Aspects of Calcium Carbonate The report provides the market value for the base year 2020 and a yearly forecast until 2028 in terms of volume (Kilotons) and revenue (USD Million). The market for each application has been provided on a regional basis for the aforementioned forecast period. STUDY OF CALCIUM CARBONATE 14 QUANTUM AND STATISTICAL REPORT The key industry dynamics, regulatory scenario, and application markets are evaluated to understand their impacts on the product demand over the forecast period. The growth rates were estimated using correlation, regression, and time-series analysis. We have used the bottom-up approach for market sizing, analyzing key regional markets, dynamics, and trends for various products, services, and end uses. The global market has been estimated by integrating the regional markets. All market estimates and forecasts have been validated through primary interviews with the key industry participants Inflation has not been accounted for in order to estimate and forecast the market Numbers may not add up due to rounding off North America includes the U.S., Canada, and Mexico Europe consists of EU-28, Central & Eastern Europe along with. Commonwealth of Independent States (CIS) Turkey has been considered as a part of Europe Asia Pacific includes South Asia, East Asia, Southeast Asia, and Oceania (Australia & New Zealand) Central & South America includes Central American countries (excluding Mexico) and the South American continent. The Middle East includes Western Asia (as assigned by the UN Statistics Division) and the African continent The global calcium carbonate market was valued at USD 39,179.27 million in 2020 and is projected to reach a value of USD 60,702.1 million by 2028. Increasing use of calcium carbonate in the day to day items such as paper, plastic, cosmetics, etc. is expected to drive the market in the forecast period. Health & hygiene awareness are likely to have a remarkable impact on the consumption of paper in the form of tissues and packaging material. These increased consumption levels are considered to be the boosting factors for the growth of the product over the forecast period. Figure 9 Calcium Carbonate market revenue 20172028 Owing to the high demand from paper sector coupled with rising population in countries such as India and China, Asia Pacific market gained highest market share in 2020. Healthy upsurge in the consumption of paper products in India is projected to be a key driver for the growth of the calcium carbonate market in the Asia Pacific region. As per the stats released by the Indian Paper Manufacturers Association (IPMA), per capita consumption in the country is expected to grow from 13 kilograms in 2018 to nearly 17 kilograms by 2024. Given, the population size of India, this is likely to offer huge opportunity to the vendors of calcium carbonate in the region. STUDY OF CALCIUM CARBONATE 15 QUANTUM AND STATISTICAL REPORT Figure 10 Estimation of India print media Nano calcium carbonate products are anticipated to provide new avenue for market vendors over the coming years. Increasing utilization of plastics and rubber in automotive sector along with rising R&D activities to develop new products is projected to propel the demand for nano calcium carbonate products. Indian paper sector is projected to play a key role in positively influencing the demand for calcium carbonate products 9. References https://www.image.org/page/what_is_cal cium_carb https://medlineplus.gov/druginfo/meds/a 601032.html#:~:text=Calcium%20carbo nate%20is%20a%20dietary,acid%20indi gestion%2C%20and%20upset%20stoma ch. https://en.wikipedia.org/wiki/Calcium_c arbonate https://pubchem.ncbi.nlm.nih.gov/compo und/Calcium-carbonate http://www.ema.europa.eu/docs/en_GB/ document_library/Referrals_document/ Calcitugg_30/WC500010592.pdf http://www.efsa.europa.eu/en/efsajourna l/doc/2318.pdf M.J. O’Neil, P.E. Heckerman, C.B. Koch, K.J. Roman, C.M. Kenny, M.R. D’Arecca, Calciumcarbonate (1697), in: The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals, 14th ed., Merck & Co. Inc., Whitehouse Station, NJ, 2006. http://www.drugs.com/comments/calciu m-carbonate https://www.medicines.org.uk/emc/searc h http://drugsjo.blogspot.com https://geologyscience.com/minerals/cal cite/#:~:text=Calcite%20is%20a%20roc k%2Dforming,beautiful%20developmen t%20of%20its%20crystals. https://geologyscience.com/minerals/ara gonite/#:~:text=Aragonite%20is%20a% 20high%20pressure,replaced%20by%20 calcite%20in%20fossils. https://geologyscience.com/minerals/dol omite/ https://en.wikipedia.org/wiki/Calcium_c arbonate United States Pharmacopeia Convention, United States Pharmacopeia 38/National Formulary 33 (USP 38/NF 33), Description and Solubility, vol. 1, USP Convention Inc., Maryland, 2015. European Pharmacopeia (Eur. Ph.), Calcium Carbonate, eighth ed., European Directorate for the Quality of Medicines, Strasbourg, France, 2015. STUDY OF CALCIUM CARBONATE 16