Magnesium Hydroxide
Magnesium Hydroxide is an inorganic magnesium salt with the formula Mg(OH)₂ and a molar mass of 58.32 g/mol. It comes as a white powder or as a thick, opaque aqueous suspension known historically as milk of magnesia.
The compound is essentially insoluble in water yet strongly alkaline, with a saturated slurry pH around 10.5. That combination of low solubility and high reserve alkalinity underlies its three primary commercial roles: as an antacid and laxative in pharmaceuticals, as a halogen-free flame retardant in polymers, and as a wastewater neutralisation reagent.
We source bulk Magnesium Hydroxide from top China manufacturers for our partners. The manufacturers are in Hebei. A smaller requirement can ship in a combined container with other ingredients.
Please send the grade you need, the volume and your destination port, and we will come back with a solution and a price.
or call +86-21-6858 0751
- Packaging
- 25 kg kraft paper bag with PE inner liner
- ISO 9001
- HACCP
- Halal
- Kosher
Specifications
| Item | Specification |
|---|---|
| Appearance | White fine powder, odourless |
| Assay (as Mg(OH)₂, ignited basis) | 95.0-100.5% |
| Magnesium Oxide (as MgO) | ≥ 65.0% |
| Loss on Ignition (800°C) | 30.0-33.0% |
| Acid-Insoluble Matter | ≤ 0.1% |
| Calcium (as CaO) | ≤ 1.5% |
| Chloride (as Cl) | ≤ 0.1% |
| Sulfate (as SO₄) | ≤ 0.5% |
| Soluble Alkalies (as Na₂O) | ≤ 1.0% |
| Iron (as Fe) | ≤ 0.05% |
| Heavy Metals (as Pb) | ≤ 10 mg/kg |
| Lead (as Pb) | ≤ 2 mg/kg |
| Arsenic (as As) | ≤ 3 mg/kg |
| Total Plate Count | ≤ 1,000 cfu/g |
| Escherichia coli | Negative/25g |
Common Markets Grades
Magnesium Hydroxide is graded by particle shape, surface area, and application area.
USP pharmaceutical grade is a fine, low-iron powder with controlled limits on chloride, sulphate, calcium oxide, soluble salts, and heavy metals. It is the format used for oral suspensions, chewable antacid tablets, and combination antacid-simethicone products.
Food-additive grade matches FCC and the E528 specification, used as an alkali, colour stabiliser, and acidity regulator.
Flame-retardant grades are surface-treated platelet-shaped powders with mean particle sizes between 0.8 and 5 µm. The platelets are typically coated with stearic acid, aminosilane, or vinylsilane to improve dispersion into polyethylene, EVA, and engineering thermoplastics.
Industrial slurry grades are 50 to 60 percent solids aqueous suspensions for wastewater pH adjustment, flue-gas desulfurization, and acid mine drainage neutralisation.
Applications
- Oral antacid in chewable tablets, liquid suspensions, and combination products with aluminium hydroxide and simethicone
- Saline laxative in pediatric and adult oral suspensions, marketed historically as milk of magnesia
- Halogen-free flame retardant in wire and cable jacketing, polyolefins, EVA, and engineering thermoplastics
- Smoke suppressant in rubber and elastomer compounds for transit and construction applications
- Wastewater neutralisation for heavy-metal precipitation in acid mine drainage and industrial effluent
- Flue-gas desulfurization scrubbing reagent at power plants and industrial boilers
- Sugar refining as a clarification and decolorisation aid
- Colour stabiliser in canned vegetables and pickled products
- Pulp and paper bleaching as an alkali source in peroxide-stage brightening
- Pharmaceutical excipient as a buffer and acid-neutralising component in oral solid-dosage forms
- Personal-care deodorants positioned on aluminium-free claims
Brands Using Magnesium Hydroxide
Widely-distributed consumer products that list Magnesium Hydroxide on the ingredient label.
- Bayer (Phillips')Phillips' Milk of Magnesia Original Liquid Laxative ↗#1 milk of magnesia brand; each 15 mL dose contains 1200 mg magnesium hydroxide; relieves occasional constipation overnightLabel verified 2026-05-24
- Sanofi (Maalox/Mylanta-style)Maalox Maximum Strength Antacid (Aluminum/Magnesium Hydroxide Oral Suspension) ↗Standard Maalox formulation contains 200 mg aluminium hydroxide, 200 mg magnesium hydroxide, and 20 mg simethicone per 5 mLLabel verified 2026-05-24
Brand names, product names and logos are the property of their owners. They appear here as published evidence that the ingredient is used, taken from the brand's own label or website. Their appearance is not an endorsement, and it does not mean the brand buys from us or from any manufacturer listed on this site.
China Manufacturers of Magnesium Hydroxide
Top Magnesium Hydroxide manufacturers in China.
Hebei Meishen Technology Co., Ltd.4 ingredients in the directory
Hebei Messi Biology Co., Ltd.4 ingredients in the directory
Company names and logos are the property of the manufacturers themselves. They are listed here because our own directory records them as producing this ingredient. A listing is not an endorsement by them, and we do not represent them or speak on their behalf.
How We Help Source Magnesium Hydroxide
Direct Factory Sourcing
We run the whole process: selecting the manufacturer from the top Chinese food ingredient producers, negotiating the price, verifying quality, and coordinating the logistics. You deal with us instead of with several factories at once.
Original Packaging and Documents from the Manufacturer
The manufacturer sends your Magnesium Hydroxide out of its own factory in the original packing, through to your destination port. The COA, COO, MSDS, TDS and any certifications reach you from the manufacturer as well.
Free Samples and Lead Time
We send 100 to 500 g free for your own laboratory to test and you cover only the courier, usually within 2 to 3 working days. ETD is usually within 7 to 15 days once the order is confirmed, and we check that date against the factory's own manufacturing schedule before we give it to you.
Combined Shipment
We can load Magnesium Hydroxide together with other ingredients such as Sodium Acetate, Calcium Citrate and Sodium Lactate into one 20' FCL. If your quantity is small, we can also ship LCL.
Regulatory Status
Magnesium Hydroxide is approved for food, pharmaceutical, and industrial use in essentially every regulated market.
In the European Union it carries the additive number E528 as an acidity regulator and colour stabiliser with quantum satis authorisation in defined categories.
The U.S. Food and Drug Administration recognises the substance as GRAS under 21 CFR 184.1428, with specific direct-food provisions. It also holds OTC monograph status as an antacid and as a saline laxative.
JECFA has reviewed magnesium salts as a group and assigned them acceptable status for use as food additives.
Pharmacopoeial monographs appear in the United States Pharmacopeia (USP), the European Pharmacopoeia (Ph. Eur.), the British Pharmacopoeia (BP), and the Japanese Pharmacopoeia (JP). Halal and Kosher certifications are routine for the synthetic and seawater-derived grades.
Manufacturing Process
Two industrial routes dominate global supply.
The dominant route is precipitation from seawater or magnesium-rich brine. Filtered seawater is reacted with slaked lime, Ca(OH)₂, in a large reactor known as a flocculator. Magnesium hydroxide precipitates as a fine, voluminous floc while calcium remains in solution as calcium chloride. The floc is thickened, washed in counter current flow to remove sodium and chloride, and either dewatered to the slurry product or dried and calcined for further processing.
The brucite route grinds and beneficiates the natural mineral brucite, Mg(OH)₂, mined in China, Russia, and Canada. The mineral product is purer than seawater material in trace elements but coarser in particle size, and is the main feed for flame-retardant grades after milling and surface treatment.
A synthetic high-purity route reacts magnesium chloride with sodium hydroxide in stirred reactors, with strict control of supersaturation and seeding to deliver the platelet shape and narrow particle-size distribution required for polymer compounding.
