546-93-0/Magnesium carbonate

Magnesium Compounds

Compound ? ? ? ? ? ? ? ? Mineral ? ? ? ? ? ? ? ?Formula ? ? ? ? ? ? ? ? ? ? CAS No. anhydrous salt ? ? ? ? ? ? magnesite ? ? ? ? ? ? ?MgCO3 ? ? ? ? ? ? ? ? ? ? ? [13717-00-5] dihydrate ? ? ? ? ? ? ? ?barringtonite ? ? ? ? ? MgCO3?2H2O ? ? ? ? ? ? ? ? ? ?[5145-48-2] trihydrate ? ? ? ? ? ? ??nesquehonite ? ? ? ? ??MgCO3?3H2O ? ? ? ? ? ? ? ? ? ?[14457-83-1] pentahydrate ? ? ? ? ? ? ?lansfordite ? ? ? ? ? ?MgCO3?5H2O ? ? ? ? ? ? ? ? ? ? [61042-72-6] basic carbonate ? ? ? ? ? ?artinite ? ? ? ? ? ? ?MgCO3?Mg(OH)2?3H2O ? ? ? ? ? ? ??[12143-96-3] basic carbonate ? ? ? ? ? ?hydromagnestite ? ? ? ??4MgCO3?Mg(OH)2?4H2O ? ? ? ? [12072-90-1] basic carbonate ? ? ? ? ? ?dypingite ? ? ? ? ? ??4MgCO3?Mg(OH)2?5H2O ? ? ? ? ? ? ? ?[12544-02-4] basic carbonate?? ? ? ? ? ? ?--- ? ? ? ? ? ? ? 4MgCO3?Mg(OH)2?8H2O ? ? ? ? ? ? ? ?[75300-49-1]

Occurrence and Uses

Magnesium carbonate occurs in nature in several minerals as hydrated, basic and double salts, as shown above. The two principal minerals are magnesite, MgCO3 and dolomite, a double salt, CaCO3?MgCO3. Both minerals are used as source materials in the production of magnesium metal. Also, they are calcined to produce basic refractory bricks. Other applications of magnesium carbonate are in flooring, fireproofing and fire-extinguishing compositions; as a filler material and smoke suppressant in plastics; as a reinforcing agent in neoprene rubber; as a drying agent and for color retention in foods; in cos-metics; in dusting powder; and in toothpaste. The high purity magnesium carbonate is used as an antacid in medicine; and as an additive to table salt. Another important application of magnesium carbonate is as a starting material in producing a number of magnesium compounds.

Physical properties

This material is available in a very light, fluffy grade which absorbs well. The before-mentioned qualities are why magnesium carbonate is often used to absorb perfume before incorporation into face powders.

Definition

The term magnesite is loosely used as a synonym for magnesia as are also the terms caustic-calcined magnesite, dead-burned magnesite, and synthetic magnesite.

Production Methods

Depending upon the manufacturing process used, the composition of the magnesium carbonate obtained may vary from normal hydrated magnesium carbonate to basic hydrated magnesium carbonate. Light magnesium carbonate may be manufactured by saturating an aqueous suspension of dolomite, CaMg(CO3)2, with carbon dioxide under pressure. On increase of the temperature, calcium carbonate precipitates almost entirely. The filtered solution is then heated to boiling; the magnesium bicarbonate in the solution loses precipitates. Heavy magnesium carbonate may be manufactured by mixing a hot concentrated solution of magnesium chloride or magnesium sulfate with a solution of sodium carbonate. The heavy magnesium carbonate may be either precipitated to produce a granular material or spray-dried. Varying the temperature of the reaction solutions produces heavy magnesium carbonate with differing physical properties: e.g. material with a higher specific surface area is produced at a lower reaction temperature. Low processing temperature provided the largest surface area, which produced optimum granules or spray-dried powder.If dilute magnesium chloride or magnesium sulfate solutions are used for the reaction, a less dense material is produced. Magnesium carbonates in varying states of hydration are also found as minerals in nature.

General Description

White, yellowish, grayish-white or brown crystalline solid or crystalline powder. Density: 3-3.1 g cm-3. An important ore for magnesium. Used in the manufacture of materials capable of withstanding very high temperatures. Sometimes used to produce carbon dioxide.

Reactivity Profile

Magnesium carbonate has generally low chemical reactivity. Non-flammable and non-combustible. Reacts with acids and acidic salts to generate gaseous carbon dioxide with effervescence (bubbling). The reaction may be rapid and exothermic with concentrated solutions of acids. The efferversence can create foaming. Incompatible with formaldehyde.

Hazard

A nuisance particulate.

Health Hazard

Magnesite is considered to be a nuisance dust.

Flammability and Explosibility

Nonflammable

Pharmaceutical Applications

As an excipient, magnesium carbonate is mainly used as a directly compressible tablet diluent in concentrations up to 45% w/w. Heavy magnesium carbonate produces tablets with high crushing strength, low friability, and good disintegration properties. However, magnesium carbonate can have varying effects on dissolution and stability.Magnesium carbonate has been incorporated in microsphere formulations for the purpose of stabilizing encapsulated proteins. It has also been coencapsulated in poly(lactide-co-glycolide) microsphere formulations to neutralize acidity and enhance the immunogenicity of a contraceptive peptide vaccine. Magnesium carbonate is also used to absorb liquids, such as flavors, in tableting processes. Magnesium carbonate is additionally used as a food additive and therapeutically as an antacid.

Agricultural Uses

Hydromagnesite is a magnesium ore which occurs as a carbonate. Magnesium carbonate occurs in a mixed salt dolomite (CaCO3.MgCO3) and as basic magnesium carbonate in two minerals, namely, artinite (MgCO3.Mg(OH)2.3H2O) and hydromagnesite (3MgCO3.Mg(OH)2.3H2O).

Safety

Magnesium carbonate is used as an excipient in oral solid-dosage pharmaceutical formulations and is generally regarded as an essentially nontoxic and nonirritant material. However, the use of magnesium salts, such as magnesium carbonate, is contraindicated in patients with renal impairment. In certain studies, magnesium carbonate has been shown to be an effective phosphate binder in short-term use for patients with chronic kidney disease, but the effects of long-term use require further study.The probable oral lethal dose in humans has been estimated at 0.5–5.0g/kg bodyweight. On contact with gastric acid, magnesium carbonate reacts in the stomach to form soluble magnesium chloride and carbon dioxide. Magnesium carbonate should therefore not be used as an antacid by those individuals whose stomachs cannot tolerate the evolution of carbon dioxide. Some magnesium is absorbed but is usually excreted in the urine. As with other magnesium salts, magnesium carbonate has a laxative effect and may cause diarrhea. Therapeutically, the usual dose of magnesium carbonate as an antacid is 250–500mg, and 2.0–5.0g as a laxative.

storage

Magnesium carbonate is stable in dry air and on exposure to light. The bulk material should be stored in a well-closed container in a cool, dry place.

Incompatibilities

Incompatible with phenobarbital sodium,diazepam solution at a pH≥5, some binary powder mixtures, lansoprazole, and formaldehyde. Acids will dissolve magnesium carbonate, with the liberation of carbon dioxide. Slight alkalinity is imparted to water. Magnesium carbonate was also found to increase the dissolution of acetazolamide formulations at a pH of 1.12; however, dissolution was retarded at a pH of 7.4.

Regulatory Status

GRAS listed. Accepted as a food additive in Europe. Included in the FDA Inactive Ingredients Database (oral capsules and tablets). Included in nonparenteral medicines licensed in the UK.