1. Environmental Treatment Field
This is one of the largest application fields for magnesium hydroxide.
Acidic Wastewater Neutralizing Agent:
Principle: Magnesium hydroxide is a mild alkaline substance that can react with acids.
Advantages: Compared to traditional lime (calcium hydroxide), magnesium hydroxide offers strong buffering capacity, smooth and steady neutralization, no scale formation from precipitation, good flocculation effects, and produces denser sludge with smaller volume. It can stabilize wastewater pH within the ideal range of 6-9, avoiding localized over-alkalinity, while effectively removing heavy metal ions.
Applications: Widely used in acidic wastewater treatment from industries such as mining, metal smelting, dyeing, and chemical production.
Heavy Metal Adsorbent and Decolorizing Agent:
Principle: The flocculent precipitate formed by magnesium hydroxide in water has a large specific surface area with active adsorption sites.
Applications: Effectively adsorbs and co-precipitates various heavy metal ions (e.g., lead, cadmium, chromium, arsenic) and dye molecules in industrial wastewater, enabling water purification and decolorization.
Flue Gas Desulfurization:
Principle: A magnesium hydroxideslurry can react with sulfur dioxide (SO₂) in flue gas to form magnesium sulfite or magnesium sulfate.
Advantages: High desulfurization efficiency, equipment is less prone to scaling and clogging, and the by-products can be recycled or safely disposed of. It is a promising wet flue gas desulfurization technology.
2. Flame Retardant Field
Magnesium hydroxide is an important inorganic flame retardant.
Flame Retardant Mechanism:
1.Endothermic Decomposition: When the temperature reaches around 340°C, magnesium hydroxide decomposes, absorbing a significant amount of heat (endothermic effect), thereby lowering the surface temperature of the burning material.
2.Oxygen Dilution: The water vapor released during decomposition dilutes the concentration of combustible gases and oxygen.
3.Barrier Formation: The magnesium oxide formed after decomposition is a high-temperature-resistant, dense solid that covers the material surface, providing insulation and isolating oxygen.
Advantages:
Environmentally Friendly and Non-Toxic: Does not produce toxic, harmful, or corrosive gases, meeting modern environmental requirements.
Excellent Smoke Suppression: Significantly reduces the amount of smoke produced when plastics, rubber, and other materials burn.
Applications: Widely added to polymer materials such as polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), wires & cables, and rubber products. Surface modification is often required to improve its dispersion and compatibility within polymers.
3. Pharmaceutical and Food Industry
Antacid: Utilizes its mild alkalinity in the production of stomach medicine and antacid tablets to neutralize excess stomach acid, relieving stomach pain and heartburn. Its action is gentler than aluminum hydroxide and does not cause constipation or the risk of aluminum toxicity.
Food Additive: Used as a processing aid, pH regulator, etc., in the production of products like sugar and cheese.
4. Chemical Raw Material and Additive
Production of Magnesium Oxide: Calcining (heating) magnesium hydroxide produces high-purity magnesium oxide, used in refractory materials, ceramics, electronics, and other industries.
Production of Magnesium Salts: Serves as an intermediate or raw material for producing other magnesium salts (e.g., magnesium sulfate, magnesium carbonate).
Oil Refining: Used as a degumming agent and neutralizing agent in the refining process of vegetable oils to remove free fatty acids and phospholipids.
Toothpaste Abrasive: Used as a mild abrasive in some toothpaste formulations.