As an essential chemical material, precipitated barium sulphate has many uses such as filler for paints, coatings, inks, plastics, rubber, and batteries, surface coating agent for printing paper and copper plate paper, sizing agent for the textile industry, clarifying agent for glass products and is also used in porcelain and dyestuff industries. Currently, there are mainly two methods to produce precipitated barium sulphate: the Sodium sulphate Method and the Sulfuric Acid Method.
Sodium Sulphate Method to Produce Precipitated Barium Sulphate
The Sodium Sulphate Method is the market’s most mainstream precipitated barium sulphate production method. Natural barite is converted to barium sulphide by calcination with coal and then reacts with sodium sulphate to produce precipitated barium sulphate and by-product sodium sulphide.
The reaction equation:
BaSO4 + 4C → BaS + 4CO
BaS + NaSO4 → BaSO4+ NaS
- Crushing: The barite and raw coal are crushed by a crusher and stored in a raw material bin of coarse barium.
- Grinding: The fuel coal is crushed and conveyed to the Raymond machine for grinding. The qualified coal powder is then sent to the coal powder combustion system of the coarse barium rotary kiln and the blower also sprays the powder to the converter for combustion.
- Calcination: The crushed barite and coal powder enter the rotary kiln for a reduction reaction to make coarse barium sulphide.
- Leaching: The coarse barium sulphide prepared by the coarse barium rotary kiln is poured into the leaching tank with a crane, then the dilute barium sulphide solution and the filtered mother liquor from the drying section are leached to obtain the barium sulphide solution.
- Nitrate: A certain amount of barium sulphate wastewater (dilute sodium sulphide solution) is placed in the nitrate tank and heated to above 40°C with steam. Start the mixer, input the sodium sulphate into the tank, and continue to heat up to 90°C. After removing magnesium and calcium by sodium sulphide, the mass concentration of nitrate water is controlled at 1.1995-1.2198 kg/L and finally input into the clarification tank for backup.
- Compounding: After clarifying the above two solutions, they are put into a compound tank in a certain proportion for metathesis reaction. The obtained barium sulphate slurry is then subjected to liquid-solid separation by a centrifuge, and the separated filter cake enters the drying system.
- Drying: Barium sulphate filter cake is then dried, graded, and packaged after stirring and crushing by the feeder.
Sulfuric Acid Method to Produce Precipitated Barium Sulphate
The Sulfuric Acid Method is to convert barium sulfide into barium carbonate through carbon dioxide and then reacts with pure sulfuric acid to produce precipitated barium sulphate.
The reaction equation:
BaS+CO2+H2O → BaCO3+H2S
BaCO3+H2SO4 → BaSO4+H2O+CO2
It can be seen from the production process that the free barium, odor (residual sulfur ions), impurities, and whiteness of precipitated barium sulphate by the Sulfuric Acid Method are several steps higher than that of the Sodium Sulphate Method. It also costs much higher to produce precipitated barium sulphate.
Related Reading: A Complete Guide To Precipitated Barium Sulphate