Magnesium Carbonate, Magnesium Hydroxide Carbonate, Magnesite, Magnesium Carbonate Hydrate​​​​​​​, Hydromagnesite, E504, 546-93-0, 12125‑28‑9

Magnesium Carbonate, Magnesium Hydroxide Carbonate, Magnesite, Magnesium Carbonate Hydrate, Hydromagnesite, E504, 546-93-0, 12125‑28‑9

• 546‑93‑0 (anhydrous magnesium carbonate)

• 12125‑28‑9 (basic magnesium carbonate / hydromagnesite)

Magnesium Carbonate (E504)

1. Introduction

Magnesium carbonate is one of the most important inorganic compounds of magnesium. It occurs naturally as the mineral magnesite and is also produced synthetically. It has a wide range of applications in the food, pharmaceutical, cosmetic, plastics, and flame-retardant industries. As a food additive, it is designated with the E number E504.

This overview covers its chemical identity, production methods, physical and chemical properties, and all major applications.

2. Identity and Nomenclature

Note: Commercial products exist in various hydrated forms: anhydrous (MgCO₃), dihydrate (MgCO₃·2H₂O), trihydrate (MgCO₃·3H₂O), tetrahydrate (MgCO₃·4H₂O), and as hydromagnesite [Mg₅(CO₃)₄(OH)₂·4H₂O] or other basic carbonates. The choice of form affects bulk density, flowability, and application suitability.

3. Natural Occurrence

Magnesium carbonate is found in nature primarily as the mineral magnesite (MgCO₃). It also occurs in combination with calcium carbonate as dolomite (CaMg(CO₃)₂) and is present in dolomitic limestone deposits. While some countries exploit natural magnesite deposits, others produce the compound synthetically.

4. Production Methods

4.1. Production from Dolomite (Wet Carbonation)

1. Dolomite (CaMg(CO3)2CaMg(CO3​)2​) is suspended in water.

2. Carbon dioxide (CO2CO2​) is introduced under pressure.

3. Calcium carbonate (CaCO3CaCO3​) precipitates, while magnesium bicarbonate (Mg(HCO3)2Mg(HCO3​)2​) remains in solution.

4. The solution is filtered to remove calcium carbonate.

5. The filtrate is heated to boiling; magnesium bicarbonate decomposes, and pure magnesium carbonate precipitates.

This process typically yields the light form of magnesium carbonate.

4.2. Chemical Precipitation (Heavy Form)

1. A hot, concentrated solution of magnesium chloride (MgCl2MgCl2​) or magnesium sulfate (MgSO4MgSO4​) is prepared.

2. This solution is mixed with a sodium carbonate (Na2CO3Na2​CO3​) solution.

3. Magnesium carbonate precipitates.

4. The precipitate is obtained in granular form and dried using spray drying.

This method produces the heavy form of magnesium carbonate. By controlling the reaction temperature, particle size and physical properties can be tailored.

4.3. Technical vs. Food Grade

Depending on raw material purity and processing conditions, both technical grade and food grade (E504) products are available. Food grade must meet strict purity limits, especially for heavy metals.

5. Physical and Chemical Properties

5.1. Appearance and Sensory Properties

• Color: White

• Form: Light, free-flowing powder

• Taste: Slightly earthy, alkaline

• Odor: Odorless, but has a high capacity to absorb odors

5.2. Thermal Properties

• Melting Point: 990 °C (decomposes)

• Behavior on Heating: Upon heating, it decomposes to magnesium oxide (MgO) and carbon dioxide (CO₂), releasing acrid fumes.

5.3. Density

• Density: 3.05 g/cm³ (anhydrous form)

5.4. Solubility

• Water: Insoluble

• Dilute Acids: Soluble with effervescence (releases CO₂). This property is key to its use as an antacid.

5.5. Stability

• Air Stability: Stable under normal conditions.

• Hygroscopicity: Low, but certain forms (especially light grades) have a high surface area and can absorb moisture and odors.

6. Applications

6.1. Food Industry (E504)

As a food additive (E504), magnesium carbonate serves several functions:

• Anti-caking Agent: Prevents clumping in salt, sugar, baking powder, spices, and powdered mixes.

• Carrier / Filler: Ensures even distribution of flavors, colors, and sweeteners in dry blends.

• Acidity Regulator: Helps control pH in some food products.

• Color Retention: Assists in preserving natural colors.

6.2. Pharmaceutical and Nutraceutical Applications

• Magnesium Source: Used in tablets and powders to supplement magnesium intake. It reacts with gastric acid to form magnesium chloride, which is absorbable.

• Inert Binder (Excipient): Acts as a filler in tablet formulations, providing bulk and mechanical integrity.

• Antacid: Neutralizes excess stomach acid, providing relief from heartburn and indigestion.

6.3. Plastics, Rubber, and Flame Retardancy

• Flame Retardant / Smoke Suppressant: Added to plastics and rubber compounds; when heated, it releases water vapor and CO₂, inhibiting flame spread and reducing smoke.

• Filler: Lowers production costs and can improve certain mechanical properties.

6.4. Cosmetics and Personal Care

• Odor Absorber: Used in talcum powders, foot powders, deodorants, and soaps to absorb moisture and odors.

• Lubricant / Slip Agent: Provides a smooth feel in skin care products.

6.5. Sports (Climbing, Weightlifting, Gymnastics)

• Chalk: Magnesium carbonate is the primary ingredient in athletic chalk. It absorbs sweat from the hands, improving grip and reducing slippage.

6.6. Refractory Materials

• Thermal Insulation: With its high decomposition temperature (990 °C), it is used in furnace linings, kiln furniture, and insulating boards.

6.7. Other Specialized Uses

• Taxidermy: Used as a paste to degrease and whiten skulls and bones.

• Upholstery and Fire Extinguishers: Incorporated into materials to impart flame resistance; also used in some dry powder fire extinguishers.

7. Safety, Handling, and Storage

7.1. Safety Considerations

• Toxicity: Generally recognized as safe (GRAS) when used appropriately.

• Inhalation: Fine dust may irritate the respiratory tract; use of a dust mask is recommended during handling.

• Eye Contact: May cause mechanical irritation; rinse with water.

• Fire Hazard: Non-flammable, but when strongly heated it decomposes to release irritating fumes.

7.2. Storage

• Store in a cool, dry, well-ventilated area.

• Keep away from strong acids and oxidizing agents.

• Because it can absorb odors, store in tightly closed containers.

7.3. Regulatory Status

• Food Additive: Approved as E504 in the European Union, Turkey, and many other countries.

• Pharmaceutical Grades: Available in compliance with USP (United States Pharmacopeia) or Ph. Eur. (European Pharmacopoeia) standards.

8. Conclusion

Magnesium carbonate (E504) is a versatile compound available from natural and synthetic sources. Its key properties—insolubility in water, effervescent solubility in acids, high thermal stability, and excellent moisture/odor absorption—make it indispensable across multiple industries.

Whether used as an anti-caking agent in food, a magnesium supplement in pharmaceuticals, a flame retardant in plastics, or a grip enhancer in sports, it delivers reliable performance. The availability of light and heavy forms, along with different hydration states, allows manufacturers to select the optimal grade for each application.

1. Main Product Types: Light vs. Heavy

The most fundamental classification of Magnesium Carbonate is based on its bulk density, which dictates its behavior and primary use. Both forms are white, odorless powders that are practically insoluble in water .

2. Detailed Applications by Industry

The versatility of Magnesium Carbonate is evident in its use across a vast range of sectors. Its primary functions can be categorized as an antacid, a source of magnesium, an anti-caking agent, a drying agent, a smoke suppressant, and a reinforcing agent .

Pharmaceuticals & Nutraceuticals (The Largest Application)

This sector accounts for about 24% of the global market share . The compound is valued for its safety and functionality.

• Antacid: It is a key ingredient in over-the-counter preparations to neutralize excess stomach acid, providing relief from heartburn and indigestion .

• Dietary Supplement: It serves as a primary source of magnesium, an essential mineral for bone health, muscle function, and nerve transmission .

• Pharmaceutical Excipient: It acts as a direct compression diluent and a disintegration aid in tablet formulations. It also functions as a glidant to improve the flow of powder mixtures and as a lubricant during the tableting process .

Food Industry (as E504)

As a food additive, it is primarily used for quality and preservation.

• Anti-caking Agent: It is widely used in powdered foods like salt, sugar, baking powder, spices, and ready-mix flours to prevent clumping and ensure free-flowing properties .

• Color Retainer: It helps stabilize and retain the natural green color of certain foods like vegetables .

Sports & Fitness

• Athletic Chalk: In gymnastics, weightlifting, rock climbing, and yoga, it is the standard for drying hands, absorbing sweat, and improving grip to enhance performance and safety .

Industrial & Technical Applications

• Plastics & Rubber: It is used as a smoke suppressant and a flame retardant filler in plastics and neoprene rubber, particularly in wire and cable insulation .

• Paints, Inks & Coatings: It acts as an extender and a functional filler .

• Construction & Refractory Materials: Calcined to produce magnesium oxide (MgO), which is a key component in refractory bricks for high-temperature furnaces and kilns. It is also used in fireproofing materials and lightweight construction composites .

• Pulp & Paper Industry: Used as a filler and a neutralizing agent .

Personal Care & Cosmetics

• Cosmetic Ingredient: Incorporated into talcum powders, deodorants, and soaps due to its excellent ability to absorb moisture and odors .

• Fragrance Retainer: It helps bind and stabilize fragrances in cosmetic products .

Environmental & Agricultural Applications

• Carbon Capture: Scientists are exploring its use in carbon capture and storage (CCS) technologies due to its ability to bind with CO₂ to form stable carbonate minerals .

• Soil Amendment: It is used in agriculture to neutralize acidic soils, helping to restore pH balance and improve nutrient availability for crops .

3. Technical Specifications & Grades

• Grades: It is available in several grades, most commonly Technical Grade for industrial use and Food Grade (meeting FCC, USP, EP standards) for pharmaceuticals and food .

• Hydration States: While the basic forms are Light and Heavy, the compound can also exist in various hydrated forms, such as dihydrate, trihydrate, tetrahydrate, and pentahydrate, as well as basic carbonate forms like hydromagnesite .

• Purity: High-purity grades typically contain 40-43.5% MgO and have strict limits on impurities like heavy metals, arsenic, and calcium .

4. Safety & Handling

• Safety: Magnesium Carbonate is generally recognized as safe (GRAS). However, in powder form, it can be an irritant to the eyes and respiratory tract. Standard industrial hygiene practices, such as wearing dust masks and safety goggles, are recommended .

• Storage: It should be stored in a cool, dry place in tightly closed containers to prevent moisture absorption and contamination 

Magnesium Carbonate – Names)

1. Chemical and Mineral Names

• Magnesium Carbonate

• MgCO₃

• Magnesite (mineral name)

• Carbonic Acid Magnesium Salt

• Hydromagnesite (basic carbonate mineral)

2. Physical Form and Property Descriptors

• Light Magnesium Carbonate

• Heavy Magnesium Carbonate

• Anhydrous Magnesium Carbonate

• Basic Magnesium Carbonate

• Magnesium Carbonate Hydrate

• Magnesium Hydroxide Carbonate

3. Grade and Quality Standards (Non-Branded)

• Food Grade

• Technical Grade

• USP (United States Pharmacopeia)

• Ph. Eur. (European Pharmacopoeia)

• BP (British Pharmacopoeia)

• JP (Japanese Pharmacopoeia)

• FCC (Food Chemicals Codex)

• E504 / INS 504

4. Application‑Based Search Terms

• Antacid

• Dietary Supplement

• Magnesium Source

• Anti‑caking Agent

• Free‑flow Agent

• Flame Retardant

• Smoke Suppressant

• Filler

• Chalk (sports: climbing, gymnastics, weightlifting)

• Climbing Chalk

• Lifting Chalk

5. CAS Numbers

• 546‑93‑0 (anhydrous magnesium carbonate)

• 12125‑28‑9 (basic magnesium carbonate / hydromagnesite)