Magnesium Chloride

• ▸ De-icing and dust control: Brine for roads and unpaved surfaces.
• ▸ Oxychloride cement: Reactive salt for Sorel cement and wallboard.
• ▸ Fertilizer and feed: Magnesium source for crops and livestock.
• ▸ Boiler scale control: Used as a scale-control additive.

Magnesium chloride (MgCl₂, CAS 7786-30-3 anhydrous / 7791-18-6 hexahydrate) is a highly soluble, hygroscopic salt used for de-icing and dust control, brine and refrigeration systems, and as a coagulant and industrial feedstock. It pulls moisture from the air, dissolves readily in water, and ships as flake, pellet, anhydrous powder, or ready-mixed liquid brine. RawSource supplies it in bulk to road-maintenance crews, drilling operators, construction-products makers, and process plants across North America.

Magnesium Chloride Forms and Typical Assay

The form you buy drives both freight cost and how it dissolves on site. Hexahydrate flake carries six waters of crystallization, so much of each bag is bound water; anhydrous grades pack far more active MgCl₂ per pound but are aggressively deliquescent and harder to store. Match the form to the job before comparing price per ton.

Applications by Sector

Road De-Icing and Anti-Icing

Magnesium chloride brine stays liquid at lower temperatures than a plain sodium chloride solution, so crews use it for anti-icing — spraying pavement before a storm to keep ice from bonding. It is generally reported as less corrosive to vehicles and infrastructure than rock salt, though it is not corrosion-free; agencies that want a true low-corrosion program still specify an inhibited blend. The practical trade-off is cost: MgCl₂ brine usually runs higher than rock salt, so it earns its place on bridges, high-traffic corridors, and pre-treatment passes rather than as a blanket replacement.

Dust Control on Unpaved Roads

On gravel roads, mine haul routes, and lot surfaces, applied MgCl₂ draws moisture out of the air and holds it in the road bed. That bound moisture keeps fine particles weighted down instead of becoming airborne under traffic. Because the effect depends on humidity, it works best in climates that aren’t bone-dry for weeks at a stretch. Apply to a damp, freshly graded surface for the best penetration, and plan on periodic reapplication.

Brine, Refrigeration, and Heat Transfer

MgCl₂ brines serve as a secondary coolant in industrial refrigeration and as a heat-transfer fluid where a depressed freezing point is needed. Concentration sets the freeze protection, so specify the target percent for your loop and confirm the metallurgy of pumps and piping — chloride brines call for compatible alloys. For closed systems, request a low-impurity grade with the right inhibitor package.

Sorel (Oxychloride) Cement and Flooring

Magnesium chloride is the reactive partner to magnesium oxide in magnesium oxychloride (Sorel) cement, used in industrial flooring, grinding wheels, and fire-resistant board. The MgO-to-MgCl₂ ratio governs set behavior and final hardness, so consistent assay between lots matters more here than in de-icing. Hexahydrate flake is the common feed; lock the supplier spec to keep your formulation repeatable.

Oilfield Drilling and Completion

In drilling and completion work, MgCl₂ builds dense, clear brines and manages water activity in the fluid system. Density and clarity targets drive the grade you need, and operators typically pull a Certificate of Analysis on every lot before it goes downhole. Specify your density and turbidity limits when you request a quote.

Food Coagulant (Nigari) and Other Uses

Food-grade magnesium chloride, known as nigari, is the traditional coagulant used to set soy milk into tofu; this is provided for informational context, and any food-contact use requires the appropriate food-grade specification and documentation. The salt also appears in textile and flame-retardant treatments, in fertilizer and feed as a magnesium source, and as a general inorganic feedstock. If your application is regulated, tell us the standard it must meet and we will confirm whether a qualifying grade is available.

Handling and Storage

Magnesium chloride is strongly hygroscopic, so it cakes and can liquefy if left exposed; keep bags and super-sacks sealed and store them dry. The salt and its solutions are mildly corrosive to some metals and can irritate skin and eyes on contact. Use appropriate PPE, isolate it from incompatible metals, and consult the Safety Data Sheet for the specific grade before handling. Request the current SDS with your order.

Bulk Supply and RFQ

RawSource supplies magnesium chloride flake and pellet in bags and super-sacks, and liquid brine in totes and tankers, with truckload and container volumes available. For an accurate quote, send the form (flake, pellet, anhydrous, or brine), the target MgCl₂ percent, your volume, and any Certificate of Analysis or grade requirements. Many buyers weigh MgCl₂ against calcium chloride for de-icing and dust control — see our calcium chloride page for that comparison, and ask us if you want both quoted side by side.

Frequently Asked Questions

What is magnesium chloride used for?

Magnesium chloride (MgCl₂) is used for road de-icing and anti-icing, dust control on unpaved roads, refrigeration and heat-transfer brines, magnesium oxychloride (Sorel) cement and flooring, oilfield drilling and completion fluids, and as a textile, fertilizer, and general industrial feedstock. Food-grade material (nigari) is also used as a tofu coagulant.

What is the difference between hexahydrate and anhydrous magnesium chloride?

Hexahydrate (CAS 7791-18-6) carries six waters of crystallization and assays around 46–47% MgCl₂; it is the common flake and pellet form for de-icing, dust control, and oxychloride cement. Anhydrous (CAS 7786-30-3) is roughly 99% MgCl₂ for high-assay, low-water chemistry, but it is far more deliquescent and demands tighter storage. Choose by required assay and how the material will be stored.

Magnesium chloride vs calcium chloride for de-icing — which is better?

Both melt ice at lower temperatures than rock salt and are widely used as brines. Calcium chloride is more exothermic and often acts faster at very low temperatures, while magnesium chloride is frequently chosen where lower corrosivity is the priority. The right pick depends on temperature range, corrosion concerns, and cost per lane-mile; many agencies trial both. Ask us to quote them side by side.

How does magnesium chloride work for dust control?

Magnesium chloride is hygroscopic, meaning it attracts and holds moisture from the air. Applied to an unpaved road, it keeps the surface slightly damp so fine particles bind together instead of lifting into the air under traffic. Performance depends on ambient humidity and on applying it to a damp, graded surface, with periodic reapplication.

Is magnesium chloride hazardous to handle?

Magnesium chloride is a strongly hygroscopic salt that is mildly corrosive to some metals and can irritate skin and eyes on contact. It should be handled with appropriate PPE, kept sealed and dry, and isolated from incompatible metals. Always review the Safety Data Sheet for the specific grade before handling; request the current SDS with your order.

Is there a food-grade magnesium chloride?

Yes. Food-grade magnesium chloride, traditionally called nigari, is used as a coagulant to make tofu. Food contact applications require material that meets the applicable food-grade specification with supporting documentation. Tell us the standard your process must meet and we will confirm whether a qualifying grade is available.

How is bulk magnesium chloride packaged and shipped?

Flake and pellet ship in bags and super-sacks; liquid brine ships in totes and tankers, with truckload and container volumes available. For an accurate quote, provide the form, target MgCl₂ percent, volume, and any Certificate of Analysis or grade requirements.