Barium Sulphate - Overview
Barite (BaSO4) is a mineral consisting of barium sulfate. It is generally white or colorless, and is the main source of barium. Baryte is the British spelling, and the mineral is also called heavy spar. The radiating form, sometimes referred to as Bologna Stone, attained some notoriety among alchemists for the phosphorescent specimens found in the 1600s near Bologna, Italy by one Mr. Vincenzo Cascariolo. Its Mohs hardness is 3, the refractive index is 1.63 and it has a specific gravity of 4.3-5. Its crystal structure is orthorhombic.
Barite generally occurs in the white massive variety (often appearing earthy when weathered), although some clear to bluish, bladed barite crystals (Plate 18) have been observed in several vein deposits, and various nodular zones have been observed. Rosettes are common in many Iranian mineral veins. Feathery barite is also known from Iran.
Barite is extremely insoluble in acid and water and is therefore chemically inert. It is the principal source of the element barium. Barite is the most abundant of the semi-commercial vein-forming minerals in Iran. Until World War I, barite was mined along with fluorite and sphalerite. Limited barite mining was attempt during the 1960’s in other counties Commercial barite was recovered as a by-product of the fluorspar industry Iran during World War II and during the 1960’s.
The highly impure mineral barite is processed by heating with coke or carbon via thermal reduction to give barium sulphide. Barium sulphide is treated with sulphuric acid or sulphate salts to obtain barium sulphate of high purity. The barium sulphate produced with this method is known as “blanc fixe” which is “permanent white” in French. In the laboratory, barium sulphate is produced from combining solutions containing barium ions and sulphate salts.
The Uses of Barium Sulphate
Rubber & Plastic IndustryBarium sulfate (BaSO4), a common barium compound, is used as a filler for rubber, plastics and resins. n 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.
Paper IndustryBarium sulphate is used as a white pigment for paper pigment due to its white appearance. In ink-jet printing, barium sulfate is employed to improve the brightness and whiteness of the paper. For photographic paper, a thin layered coating of barium sulfate would help to increase the reflectiveness of the image.
Other ApplicationsBarium sulphate is used an integral component in oil well drilling fluid and it increases the density of fluid. Suspension of barium sulfate is digested orally for X-ray imaging and other clinical diagnostic procedures. As a coating agent, it is useful in the casting of copper anode plates as well. In addition, barium sulfate serves a white pigment in paints, modifying consistency in paints. Although all barium compounds are poisonous, barium sulfate can be safely ingested since it does not dissolve in water.
|Common Name||Barium Sulphate|
|Molecular Weight||233.43 g mol-1|
|Synonyms||Barium sulfate, Barite, Baryte, Heavy Spar|
|Appearance||White crystalline powder|
|Purity||%||93 - 98|
|Density at 20°C||g/cm3||4.5|
|Solubility at 20°C||g/100ml||0.0002448|
|Refractive Index at 20°C||1.64|