Magnesium sulfate is an inorganic salt of magnesium, sulfur and oxygen that appears as white crystals, granules or powder and dissolves readily in water. It is one of the most widely used water-soluble sources of both magnesium and sulfur, so it serves as a fertilizer, feed additive and industrial processing material. This versatility makes it a recurring line item for procurement teams across fertilizer, feed and industrial supply chains. As a source factory in Weifang, Shandong, Weifang Hailei Fine Chemical Co., Ltd supplies it in three forms: agriculture grade granule, heptahydrate crystal (Epsom salt) and industrial grade powder.
The three forms differ in how many water molecules are bound into the crystal, which changes concentration and handling. Heptahydrate (MgSO4·7H2O) holds seven water molecules, so pure MgSO4 is only about 49% of its weight, and it is the most common and economical form for agriculture and Epsom salt. Monohydrate (MgSO4·H2O) carries roughly 87% MgSO4, while anhydrous (MgSO4) approaches 100%, making both more concentrated options where freight and storage matter. Choose based on required magnesium content, water tolerance and handling method.
Weifang Hailei Fine Chemical Co., Ltd supplies three main grades to match different markets. The agriculture grade granule is made for field spreading and fertilizer blending, with free-flowing particles suited to broadcast equipment. The heptahydrate crystal grade, commonly called Epsom salt, is a high-purity crystalline material for agriculture, feed and personal-care-related uses. The industrial grade powder targets manufacturing where controlled impurities and fine particle size are needed.
Specifications are normally stated as assay (MgSO4), magnesium (Mg) and sulfur (S) content, appearance, particle size, water-insoluble matter, pH and loss on drying. As general industry references, heptahydrate typically runs around 98–99% MgSO4 with roughly 9.8% magnesium and 13% sulfur, while monohydrate and anhydrous carry correspondingly higher MgSO4. Agriculture grade is supplied as free-flowing granules, heptahydrate as uniform crystals, and industrial grade as a fine low-insoluble powder. A batch certificate of analysis (COA) is provided for every shipment so you can confirm exact parameters.
It is produced either by refining natural magnesium sulfate minerals or synthetically by reacting a magnesium source such as magnesium oxide or carbonate with sulfuric acid, followed by purification, crystallization and drying. The route and feedstock influence purity, trace impurities and cost. This direct factory position also shortens the supply chain and supports consistent batch-to-batch quality. As Weifang is a major Chinese base for inorganic-salt chemicals, Hailei operates as a source factory with direct control over raw materials and production, helping keep quality stable and pricing competitive for bulk buyers.
Magnesium is the central atom of chlorophyll, so it is essential for photosynthesis, while sulfur is required to build amino acids, proteins and oils. Sandy, acidic or heavily leached soils—and fields with heavy potassium use—often become deficient in both. Because magnesium sulfate supplies both nutrients in a highly water-soluble form that plants absorb quickly, it is ideal for correcting deficiencies during the growing season via soil, irrigation water or foliar spray.
Magnesium activates enzymes, supports phosphate transport and energy metabolism, and sits at the center of chlorophyll, so deficiency shows as yellowing between leaf veins, usually on older leaves first. Sulfur contributes to protein synthesis, oil content and vitamin formation, and is especially important for oilseed, cereal and legume crops. Together the two nutrients influence yield, quality and how efficiently the plant uses nitrogen and phosphorus, which is why one soluble product delivering both is so convenient. Regular application is also a low-cost way to keep soil nutrient balance steady over multiple seasons.
In feed it serves as a magnesium source that supports bone formation, nerve and muscle function and enzyme activation in livestock and poultry. It also supplies sulfur for sulfur-containing amino acids and metabolism, and in ruminants adequate magnesium helps prevent grass tetany (hypomagnesemia). Feed applications generally require a high-purity crystalline grade, so confirm that the material meets the feed-additive requirements of the destination market before ordering.
Industrial grade is used in textile dyeing and finishing, paper sizing and pulping, and as a filler or stabilizer in detergents. In construction it produces magnesium oxysulfate boards and cementitious materials, and it also appears in leather tanning, fermentation and water treatment. The fine, uniform powder grade is selected where consistent purity must avoid contaminating the final product.
Epsom salt is simply the common name for magnesium sulfate heptahydrate (MgSO4·7H2O); the two are chemically identical. The name comes from a mineral spring at Epsom in England, though today the material is made industrially in large volume. While Epsom salt is known for bath and personal-care uses, the same crystal is also widely used as a fertilizer and feed additive—the difference between markets is purity grade and packaging, not chemistry.
Begin from the end use, since each grade is optimized for a different job. Agriculture grade granule suits soil application, broadcasting and fertilizer blending, while heptahydrate crystal is better where a fully soluble, high-purity form is required, such as fertigation, foliar feeding, feed and Epsom-salt uses. Industrial grade powder fits processes needing fine particle size and controlled impurities. Also weigh delivered cost per unit of magnesium, since monohydrate or anhydrous carries more active nutrient per ton and can save freight on long routes.
Common test items include appearance, assay, magnesium and sulfur content, water-insoluble matter, chloride, heavy metals such as lead, arsenic and cadmium, pH, particle size and loss on drying. Applicable standards vary by market and end use, with different national or industry requirements for fertilizer, feed and industrial grades. Confirming the applicable standard up front helps avoid customs delays and re-testing at destination. We provide a batch COA covering the agreed parameters, and third-party inspection can be arranged on request to verify quality before shipment.
It is commonly packed in 25 kg or 50 kg bags with a moisture-resistant inner liner, or in 1000 kg jumbo bags for high-volume buyers, with other sizes available on request. Labels can be neutral or custom-branded, and palletizing is optional to ease handling and container loading. Because the product is hygroscopic, a well-sealed outer bag and inner liner are important for keeping it dry in transit and storage.
Magnesium sulfate absorbs moisture, so store it in a dry, cool, well-ventilated warehouse, on pallets off the floor, away from rain and strong acids. Keeping bags sealed until use, using moisture-proof liners and following first-in, first-out rotation all reduce caking and lumps. Granular or larger-crystal forms flow better and resist caking more than fine powder, so choosing the right physical form for your handling system matters as well.
For bulk B2B orders a common minimum is one full 20-foot container, typically about 25–28 metric tons of bagged product, while smaller trial lots and samples can often be arranged for evaluation. Lead time depends on stock availability, production schedule, order size and destination, but is generally a matter of weeks from confirmed order to shipment. As Weifang is near Qingdao port, export logistics are efficient; contact us with grade, quantity and destination for a confirmed MOQ and schedule.
Pricing is driven by raw-material costs such as sulfuric acid and the magnesium feedstock, plus energy, packaging, and the grade, purity and particle size selected. Order volume matters, since container-load quantities achieve better unit pricing than trial lots, and freight can be a large share of the landed cost for a commodity salt. Seasonal demand around planting seasons and currency movements also shift prices over time. For an apples-to-apples comparison, always request FOB versus CIF cost breakdowns when comparing suppliers.
First check whether the supplier is a genuine source factory or a trading intermediary, since a factory offers more control over quality, consistency and cost. Review capacity, quality-control systems, batch COAs, sample results, third-party inspection availability, export experience and references. Reliable communication, complete documentation and on-time delivery are as important as price; Hailei is a source factory in a major Chinese inorganic-salt base and welcomes sample and documentation requests.
Magnesium sulfate is not classified as a dangerous good, so it ships as general cargo in dry containers or by road and rail without special hazard packaging. Standard documents—commercial invoice, packing list, bill of lading, COA and a safety data sheet (SDS) where required—accompany the cargo. Import rules, labeling and any feed or fertilizer registration vary by country, so buyers should confirm local compliance with their customs broker. We prepare the needed paperwork in advance so clearance proceeds without delay.
Magnesium sulfate is a low-hazard, non-flammable material, but fine dust can irritate eyes and airways, so wear gloves, a dust mask and goggles during bulk handling. Avoid inhaling dust, wash exposed skin with water, and rinse eyes thoroughly if contact occurs. Keep it separate from food and feed ingredients unless it is a grade intended for those uses, and review the SDS provided with each shipment.
Yes, samples are available so you can test appearance, solubility, particle size and compatibility with your formulation before committing to a container. Tell us the target grade and application, and we can arrange a small sample, with sample freight handled separately from bulk pricing. Testing a sample against your own specification is a sensible qualification step, and after approval the bulk order is produced to the same standard.
For every shipment we provide a batch certificate of analysis, a safety data sheet and standard export documents including commercial invoice, packing list and bill of lading. For regulated end uses such as feed or fertilizer we can supply the quality documentation relevant to that grade, and independent third-party inspection can be arranged on request. Certification requirements vary by country and application, so confirm what your destination market needs so we can prepare the paperwork in advance.
Contact us through our websites—haileichemicals.com (English) or haileichemical.com (Chinese)—and state the grade, quantity, target specification, packaging preference and destination port. We will reply with a quotation covering price terms (such as FOB or CIF), lead time and packaging or documentation details, then issue a contract or proforma invoice once terms are agreed. Production, quality inspection and shipment follow, and our team can advise on grade selection and logistics for a workable landed cost.