Why is barium sulphate powder Better?

Barium sulphate powder is a raw material for chemical industry, which is made of barite as the main origin and processed through ore dressing, washing and grinding. It is characterized by high specific gravity(4.3-4.7g/cm3), low hardness(3-3.5Mohs) and high brittleness. Barite is almost insoluble in water, ethanol or acid, but is soluble in hot concentrated sulfuric acid. With the development of high-performance barium sulphate products, the application fields of barium sulphate are expanding. Read on to learn how it is used in various industries.

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1. Paints and Powder Coatings

Barium sulphate has low cohesiveness, low light dispersion, fine particle size, chemical and weathering resistance, making it especially suitable for filling materials of topcoats, varnishes and spray paints. Its high inertness of insoluble in water, acid or alkali, high whiteness and tiny particles can keep the color stability and surface hardness, so that the top coat is hard to be damaged in long-term exposure. Barium sulfate can also be used in primers, and thick paste coatings. Its low abrasion property during processing can ganruatee the uniformity and smoothness of the paint.

Barium sulfate used in latex paint can make it resistant to acid even when exposed to outdoor environment. Its easy dispersibility, light retention and good flowability can increase the paints&#; chemical properties. Barium sulfate used in flooring paint also has excellent properties &#; acid and alkali resistance, wear resistance, heat resistance, pressure resistance, scratch resistance and dust resistance, better than silica micro powder or quartz sand.

In powder coatings, barium sulphate filler can improve its glossiness, fluidity, and compatibility with various pigments.

2. Pigments

Barium sulphate is used as a spacer for titanium dioxide and pigments in plastics, which can reduce the amount of pigment added and save about 10% of the cost. Its light reflection maintains color stability.

Titanium dioxide or pigment particles in coatings are usually not completely dispersed, and the particles will agglomerate together causing a decrease in scattering rate and coverage, making these titanium dioxide agglomerates a great waste. The average particle size of submicron barium sulfate is about 1.3μm, which is about twice as large as titanium dioxide particles. When submicron barium sulfate is added, its mesoscopic microcrystalline particles can separate the agglomerated titanium dioxide particles.

The application of submicron barium sulfate as bulk pigment in high-end products such as spraying powder coatings, electrophoretic coatings and high gloss coatings can make the products more competitive in terms of technology and price.

3. Printing Inks

Its low abrasiveness, high gloss, color stability, low cohesion, and good flowability make barium sulphate suitable for high-quality printing ink filling.

4. Rubber

Barium sulphate is used as filler to increase the hardness of silicone rubber and reduce its elasticity. 500 mesh or less barite powder can be used in large quantities as filler in rubber products to reduce costs, improve its hardness, and increase resistance to acid, alkali and water. It also has a good reinforcing effect on natural as well as synthetic rubber.

5. Paper Coating

Barium sulphate is used in the production of paper coatings to increase gloss and fluidity, such as white transparent paper in art paper. The titanium dioxide part can be replaced by double barium sulphate without losing gloss. High-fineness barite powder can also be used as filler for white board paper and copper board paper to improve their whiteness and surface coverage.

6. Elastomer and Sealer

Barium sulphate does not contain any heavy metal or toxic gas, so it is a very good filling material for food and medical elastomer or sealer. It can increase the anti-aging property of the products.

7. Thermoplastics

As a nucleating agent with both thermal conductivity and easy flowability, barium sulphate can reduce the injection molding time of thermoplastics and improve their strength and thermal stability. It can be used as a filler for ABS plastic to improve the strength, stiffness and wear resistance of ABS plastics.

8. Adhesives

The good rheological properties, high fillability and chemical resistance of barium sulphate make it suitable for filling adhesives, unsaturated polyester and polyurethane products.

9. Glass

Barium sulphate is used as a deaerator, clarifier and flux of glass, which can increase the optical stability, gloss and strength of glass.

10. Battery

Barium sulphate is an additive added to the anode material of battery products. Precipitated barium sulphate is one of the swelling agents added to the negative electrode, which serves to improve the porosity of the electrode plate and can enhance the charging and discharging performance of the battery. The filling effect of barium sulphate which is stable in nature provides a good environment for electrochemical reaction. The high barium sulphate content and low iron content of the battery can strengthen the activity of the negative electrode plate and prevent the plate from caking. Even at minus 20-30 degrees, the battery still maintains good performance and its longevity won&#;t shrink.

11. Friction Materials

Barite has been an indispensable inorganic filler in friction materials because of its moderate hardness, high specific gravity, non-toxic and high-temperature resistance. The use of barite powder is conducive to stabilizing the friction coefficient and reducing the wear rate, so the friction surface is smooth. Therefore, barite is usually used as a friction performance modifier, the amount of which should be 8%-35%.

12. Anti-radiation

Barium sulphate can be used in the decoration of internal and external walls to effectively shield X-rays, mainly used in the dental, hospital X-ray room, and CT room that need to prevent X-rays. Radiation-proof cement, mortar and concrete are made of barium sulphate which can absorb X-rays. This can replace the use of metal lead plates.

13. Oil and Gas Drilling

200 mesh and 325 mesh barite powder is the main material of oil and gas field drilling mud. The circulating mud containing barite powder can cool the drill bit, remove the debris, and close the hole wall, thus strengthening the well wall, controlling oil and gas pressure and preventing blowout accidents.

Hoyonn Barium Sulphate

Although barium sulphate can be applied in various industries, Hoyonn barium sulphate is espacially designed for polymer products. Our Natural Barium Sulphate Series and Precipitated Barium Sulphate are the most popular for paints and powder coating products. Contact us now to get a best price!

Inorganic chemical compound

Chemical compound

Barium sulfate (or sulphate) is the inorganic compound with the chemical formula BaSO4. It is a white crystalline solid that is odorless and insoluble in water. It occurs in nature as the mineral barite, which is the main commercial source of barium and materials prepared from it. Its opaque white appearance and its high density are exploited in its main applications.[4]

Uses

Drilling fluids

About 80% of the world's barium sulfate production, mostly purified mineral, is consumed as a component of oil well drilling fluid. It increases the density of the fluid,[5] increasing the hydrostatic pressure in the well and reducing the chance of a blowout.

Radiocontrast agent

Barium sulfate in suspension is often used medically as a radiocontrast agent for X-ray imaging and other diagnostic procedures. It is most often used in imaging of the GI tract during what is colloquially known as a "barium meal". It is administered orally, or by enema, as a suspension of fine particles in a thick milk-like solution (often with sweetening and flavoring agents added). Although barium is a heavy metal, and its water-soluble compounds are often highly toxic, the low solubility of barium sulfate protects the patient from absorbing harmful amounts of the metal. Barium sulfate is also readily removed from the body, unlike Thorotrast, which it replaced. Due to the relatively high atomic number (Z = 56) of barium, its compounds absorb X-rays more strongly than compounds derived from lighter nuclei.

Pigment

The majority of synthetic barium sulfate is used as a component of white pigment for paints. In oil paint, barium sulfate is almost transparent[citation needed], and is used as a filler or to modify consistency. One major manufacturer of artists' oil paint sells "permanent white" that contains a mixture of titanium white pigment (TiO2) and barium sulfate. The combination of barium sulfate and zinc sulfide (ZnS) is the inorganic pigment called lithopone. In photography it is used as a coating for certain photographic papers.[5] It is also used as a coating to diffuse light evenly.

Light-reflecting paint for cooling

Barium sulfate is highly reflective, of both visible and ultraviolet light.[6] Researchers used it as an ingredient in paint that reflects 98.1% of solar radiation, allowing surfaces to which it has been applied to stay cooler in sunlit conditions. Commercially available white paints only reflect 80 - 90% of solar radiation.[7] By using hexagonal nanoplatelet boron nitride, the thickness of a coat of this type of paint was reduced to 0.15 mm.[6]

Paper brightener

A thin layer of barium sulfate called baryta is first coated on the base surface of most photographic paper to increase the reflectiveness of the image, with the first such paper introduced in in Germany.[8] The light-sensitive silver halide emulsion is then coated over the baryta layer. The baryta coating limits the penetration of the emulsion into the fibers of the paper and makes the emulsion more even, resulting in more uniform blacks.[9] Further coatings may then be present for fixing and protection of the image. Baryta has also been used to brighten papers intended for ink-jet printing.[10]

Plastics filler

Barium sulfate is commonly used as a filler for plastics to increase the density of the polymer in vibrational mass damping applications. In polypropylene and polystyrene plastics, it is used as a filler in proportions up to 70%. It has an effect of increasing acid and alkali resistance and opacity. Such composites are also used as X-ray shielding materials due to their enhanced radio-opacity.[11] In cases where machinability and weight are a concern, composites with high mass fraction (70&#;80%) of barium sulfate may be preferred to the more commonly used steel shields.[12]

Barium sulfate can also be used to enhance the material properties of HDPE,[13] although typically in relatively low concentrations, and often in combination with other fillers like calcium carbonate or titanium oxide.

Niche uses

Barium sulfate is used in soil testing. Tests for soil pH and other qualities of soil use colored indicators, and small particles (usually clay) from the soil can cloud the test mixture and make it hard to see the color of the indicator. Barium sulfate added to the mixture binds with these particles, making them heavier so they fall to the bottom, leaving a clearer solution.

In colorimetry, barium sulfate is used as a near-perfect diffuser when measuring light sources.

In metal casting, the moulds used are often coated with barium sulfate in order to prevent the molten metal from bonding with the mould.

It is also used in brake linings, anacoustic foams, powder coatings, and root canal filling.

Barium sulfate is an ingredient in the "rubber" pellets used by Chilean police.[14] This together with silica helps the pellet attain a 96.5 Shore A hardness.[14]

Catalyst support

Barium sulfate is used as a catalyst support when selectively hydrogenating functional groups that are sensitive to overreduction. With a low surface area, the contact time of the substrate with the catalyst is shorter and thus selectivity is achieved. Palladium on barium sulfate is also used as a catalyst in the Rosenmund reduction.

Pyrotechnics

As barium compounds emit a characteristic green light when heated at high temperature, barium salts are often used in green pyrotechnic formulas, although nitrate and chlorate salts are more common. Barium sulfate is commonly used as a component of "strobe" pyrotechnic compositions.

Copper industry

As barium sulfate has a high melting point and is insoluble in water, it is used as a release material in casting of copper anode plates. The anode plates are cast in copper molds, so to avoid the direct contact of the liquid copper with the solid copper mold, a suspension of fine barium sulfate powder in water is used as a coating on the mold surface. Thus, when the molten copper solidifies in form of an anode plate it can be easily released from its mold.

Radiometric measurements

Barium sulfate is sometimes used, besides polytetrafluoroethylene (PTFE), to coat the interior of integrating spheres due to the high reflectance of the material and near Lambertian characteristics.

3D printing of firearms

Barium sulfate is listed among the materials acceptable to the Bureau of Alcohol, Tobacco, Firearms and Explosives (BATFE) for the manufacturing of firearms and/or components that are made of plastic, to achieve compliance with the U.S. federal requirement that an X-ray machine must be able to accurately depict the shape of the plastic firearm or component.[15]

Production

Almost all of the barium consumed commercially is obtained from barite, which is often highly impure. Barite is processed by thermo-chemical sulfate reduction (TSR), also known as carbothermal reduction (heating with coke) to give barium sulfide:

BaSO4 + 4 C &#; BaS + 4 CO

In contrast to barium sulfate, barium sulfide is soluble in water and readily converted to the oxide, carbonate, and halides. To produce highly pure barium sulfate, the sulfide or chloride is treated with sulfuric acid or sulfate salts:

BaS + H2SO4 &#; BaSO4 + H2S

Barium sulfate produced in this way is often called blanc fixe, which is French for "permanent white". Blanc fixe is the form of barium encountered in consumer products, such as paints.[5]

In the laboratory barium sulfate is generated by combining solutions of barium ions and sulfate salts. Because barium sulfate is the least toxic salt of barium due to its insolubility, wastes containing barium salts are sometimes treated with sodium sulfate to immobilize (detoxify) the barium. Barium sulfate is one of the most insoluble salts of sulfate. Its low solubility is exploited in qualitative inorganic analysis as a test for Ba2+ ions, as well as for sulfate.

Untreated raw materials such as natural baryte formed under hydrothermal conditions may contain many impurities, a.o., quartz, or even amorphous silica.[16]

History

Barium sulfate is reduced to barium sulfide by carbon. The accidental discovery of this conversion many centuries ago led to the discovery of the first synthetic phosphor.[4] The sulfide, unlike the sulfate, is water-soluble.

During the early part of the 20th century, during the Japanese colonization period, hokutolite was found to exist naturally in the Beitou hot-springs area near Taipei City, Taiwan. Hokutolite is a radioactive mineral composed mostly of PbSO4 and BaSO4, but also containing traces of uranium, thorium and radium. The Japanese harvested these elements for industrial uses, and also developed dozens of &#;therapeutic hot-spring baths&#; in the area.[17]

Safety aspects

Although soluble salts of barium are moderately toxic to humans, barium sulfate is nontoxic due to its insolubility. The most common means of inadvertent barium poisoning arises from the consumption of soluble barium salts mislabeled as BaSO4. In the Celobar incident (Brazil, ), nine patients died from improperly prepared radiocontrast agent. In regards to occupational exposures, the Occupational Safety and Health Administration set a permissible exposure limit at 15 mg/m3, while the National Institute for Occupational Safety and Health has a recommended exposure limit at 10 mg/m3. For respiratory exposures, both agencies have set an occupational exposure limit at 5 mg/m3.[18]

See also

References

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