Types of Magnesium Oxide

Magnesium oxide is a pharmaceutical ingredient that occurs as an inorganic salt. It is a white solid and a principal source of magnesium and widely available in different forms. They range from light, heavy, to very light magnesium oxide. All these offered in various crystallinities, such as hydrated, basic, and carbonated forms. Simply put, magnesium oxide comes in several types for specific applications. They include:

Standard magnesium oxide

Also known as heavy magnesium oxide, it is primarily used in industries. They include refractories, agriculture, and in the manufacturing of building insulation materials. However, it's not often used in the pharmaceutical sector. Heavy magnesium oxide has a larger particle size compared to light magnesium oxide. Therefore, it has a lower surface area, an essential variable in most chemical reactions. This form of magnesium oxide is quite stable due to its high density.
Light magnesium oxide

is produced through calcination. In this process, magnesium carbonate is subjected to high temperatures. The process results in the production of magnesium oxide, carbon dioxide, and heat. They are all released during the process. Light magnesium oxide has a smaller particle size compared to Standard magnesium oxide. This makes it have a much higher surface area. The latter feature allows it to be more reactive in chemical processes. Due to its higher reactivity, light magnesium oxide is commonly used in the pharmaceutical industry compared to the heavier variant. Applications include serving as an antacid in medicine, as well as a supplement for magnesium deficiency in the body.
Ultra-fine magnesium oxide

It is produced through advanced techniques that include sublimation. Magnesium oxide undergoes sublimation to pinpoint its phase. This method greatly reduces the particle size of magnesium oxide even further than calcination. The magnesium oxide particles end up having an extremely high surface area. This significantly increases their reactivity. Thanks to this feature, ultra-fine magnesium oxide is widely applied in niche markets. They include catalysis, advanced ceramics, and composite materials. These are specialized industries that require highly reactive magnesium oxide for optimal performance.
Hydrated magnesium oxide

It contrasts with the anhydrous forms of magnesium oxide by incorporating water molecules into its structure. It does so through the reaction of magnesium oxide with water. Hydrated magnesium oxide is often discovered in pharmaceutical products such as laxatives and antacids. It is because they require a form of magnesium oxide that can easily dissolve in water to deliver magnesium ions.
Basic magnesium carbonate

It contains magnesium oxide and magnesium carbonate in different ratios. Basic magnesium carbonate will be useful where a milder alkaline substance is suitable for application. For example, in the pharmaceutical fields such as antacids. This compound helps in mitigating acidity in the stomach but does not cause irritation.

Industrial applications of Magnesium Oxide

Magnesium oxide is a crucial compound that the yearly 2021/2022 global output saw it reach approximately 4 million metric tonnes. This figure keeps increasing year by year owing to some of the diverse benefits magnesium oxide possesses. Below are some of the industry applications magnesium oxide is commonly used in:

Ceramics and Glass Manufacturing

Magnesium oxide is an important material in the production of advanced ceramics. These include electrical insulators, thermal barriers, and cataylist substrates. During ceramic production, magnesium oxide works wonders by improving mechanical strength, thermal stability, and resistance to chemical corrosion.

Furthermore, in glass manufacturing. Magnesium oxide improves the durability and optical quality of glass products. It does so by acting as a flux, reducing melting temperatures, and enhancing workability.
Refractories

Magnesium oxide is used in producing refractory bricks and linings for high-temperature furnaces, kilns, and incinerators. Magnesium oxide can withstand extreme heat and does not melt or chemically react with other materials. It makes an ideal material for such applications. Additionally, magnesium oxide helps in the formation of stable phases within refractories. The phases contribute to longer service life and improved efficiency in industrial processes.
Agriculture

Magnesium oxide is a crucial source of magnesium for plant fertilizers used in agriculture. Usually, magnesium deficiency in soil has adverse effects on crop health. It stunts the growth and affects the yields' quality. Magnesium oxide has the ability to slowly release magnesium ions into the soil. This improvement of soil mineral content and nutrition of crops gives magnesium oxide a vital role in sustainable agriculture. It ensures that crops have the required nutrients for dense growth.
Animal Feed Additives

In animal husbandry, magnesium oxide is included in livestock feed to ensure animal health. Magnesium is an essential nutrient for metabolic processes in animals. It supports nerve function, muscle contraction, and bone development.
Construction Materials

Magnesium oxide is used for making fireproof and soundproof ceiling materials. In addition, magnesium oxide is used to produce cement and light-weight aggregates. This improves the strength and durability of structures.

Detailed specifications and features of Magnesium Oxide

Features

Like any product, magnesium oxide features vary depending on the manufacturer's conditions. However, there are features common to all magnesium oxide. They include:

High Purity

Pharmaceutical grade magnesium oxide has a purity of around 99% or higher. Sometimes, depending on the client's or company's need, magnesium oxide can be treated or have some additives. These are mainly impurities or to enhance functionality. Standardly, magnesium oxide comes uncoated.

However, magnesium oxides like Coating FDC are popular among a significant number of customers. They improve health properties, increase heat resistance, and reduce chemical migration, but such magnesium oxides are more expensive.
Particle Size Distribution

Pharmaceutical grade magnesium oxide has a particle size of 3 micrometers on average. It can have a maximum to minimum of 1 and 7 micrometers, respectively. The distribution mass mean diameter of the particles should also be less than 1.5 micrometers for effective drug delivery.
pH Level

The standard pH level of magnesium oxide is between 8 and 10. Magnesium oxide is extremely basic, while hydrated magnesium has a pH of 10 to 11. Such basicness is good for antacid. But when used in drug delivery, high pH can cause degradation of sensitive biologics.

How to choose

The choice of magnesium oxide depends on such factors as the industry or application in which it will be used. Here are several key considerations regarding how to choose the various magnesium oxide types.

Specific Industry Requirements

Some industries have specific standards for the purity and particle size of magnesium oxide. For example, in healthcare and pharmaceutical industries, magnesium oxide is often needed in a particle size of 5 micrometers for effective drug delivery. In contrast, for refractory materials in the steel industry, magnesium oxide is primarily required to have high heat resistance without paying attention to particle size.
Reactivity and Surface Area

Light or ultra-fine magnesium oxides with high surface areas are ideal for chemical reactions requiring high reactivity. Examples include catalysis and ceramic production. Basic magnesium carbonate is the best for applications that demand a milder alkaline environment. These include agriculture and animal feeds.
Hydration state

Choose hydrated magnesium oxide when a soluble source of magnesium is needed, like in fertilizers and pharmaceuticals. However, stick to anhydrous magnesium oxide where high-temperature applications like refractory materials are required. They prefer the anhydrous form because, in such applications, hydration will only add weight and not contribute to anything useful.

How to use

The applications of magnesium oxide differ from industry to industry. Below are some examples:

Pharmaceuticals

Magnesium oxide is a neutralizer of stomach acidity. It does so without irritating. This quality makes it a popular choice in antacids. Magnesium oxide is a magnesium supplement that comes hydrated to ensure ease of solubility. Magnesium oxide improves bone health, nerve functioning, and muscle regulation.
Agriculture

Magnesium oxide is the go-to source for magnesium in fertilizers. Farmers mix it with water and apply it to soils lacking magnesium to boost its levels. Magnesium is an essential element for plant health. It aids in the production of chlorophyll, the organic molecule responsible for photosynthesis.
Construction

In construction, magnesium oxide is mixed with water to make MGO boards. These boards are then used to replace gypsum boards for wall construction. Besides being fireproof and durable, MGO boards are also lightweight, making them easier to transport.
Industrial applications

In industry, magnesium oxide is mixed with water to make refractory bricks. Steel and copper industries use the bricks to line up vessels and furnaces where high-heat smelting occurs. Magnesium oxide can withstand up to 2800°c. Therefore, it is ideal for such applications. Also, because of its ability to create a chemical barrier between molten metal and furnace walls.
Animal feeds

Basic magnesium carbonate features magnesium oxide and carbonate. When used in animal feeds, it increases the magnesium levels of the feeds. Improving their nutritional value is great for livestock health.

Storage and Maintenance

Magnesium oxide's storage and maintenance measures vary depending on the type. They usually range from basic magnesium carbonate, which is the least stable, to ultra-fine magnesium oxide, which is the most stable. Below are typical ways to store and maintain magnesium oxide.

Moisture Control

Magnesium oxide products like hydrated magnesium and basic magnesium carbonate are sensitive to moisture. Such products should be stored in air-tight containers. Keep them stored in low-humidity environments to prevent caking, loss of potency, and the conversion of magnesium carbonate to magnesium hydroxide.
Separation from Reactive Substances

During storage, magnesium oxide should be separated from acids and other reactive chemicals. Doing this prevents unwanted reactions that may reduce the effectiveness or contaminate magnesium oxide. Standardly, magnesium oxide should be stored in a cool environment, away from direct sunlight.
Regular Inspection

In most cases, magnesium oxide is white powder. But on rare occasions, it may become contaminated or undergo degradation. Regular inspection of stored magnesium oxide items is paramount for users to ensure they maintain quality.
Proper Handling

Dust exposure to magnesium oxide may result in respiratory irritation or other health issues. Rare, but it also has the potential to cause skin irritation. Users should always use personal protective equipment like gloves, masks, and goggles when handling magnesium oxide products.

Q&A

Are hydrated magnesium oxide and magnesium hydroxide the same?

No, hydrated magnesium oxide and magnesium hydroxide are not the same. While the two compounds contain magnesium oxide, one does not exist as the other. Hydrated magnesium oxide is an inorganic compound derived from the reaction of magnesium oxide with water.

The resulting compound possesses both magnesium and water in a molecular relationship present as a hydroxide. Common names for this compound are water glass and milk of magnesia. On the other hand, magnesium hydroxide refers to an inorganic compound created by mixing magnesium oxide with an acid. It has less water than hydrated magnesium oxide.

Which industries are the largest consumers of magnesium oxide?

The medicine and pharmaceutical industries consume the highest quantities of magnesium oxide. In medicine, magnesium oxide is used as a laxative and antacid. Magnesium oxide gives magnesium to people with deficiencies. It is also heavily used in the pharmaceutical industry when synthesizing drugs as a buffering reagent and magnesium source.

The industrial sector also heavily consumes magnesium oxide for refractory linings, thermal insulators, and tires. Agriculture is another large industry where magnesium oxide is utilized as fertilizer and animal feed additive.

What are some of the most recent advancements in magnesium oxide production?

One of the recent advancements in magnesium oxide production is using alternate feed sources. For instance, instead of using mined magnesite, calcined brucite, or seawater, cherry pomace and other organic substrates are now being used as magnesium sources.

Another advancement is the improvement of particle size and surface area in manufactured magnesium oxide. This development improves the quality of magnesium oxide refractory bricks. Recently researchers have been adding magnesium oxide to waste, such as forbidden fruit and recycled glass. Adding magnesium to waste improves the quantity of magnesium produced while minimizing waste.