Production of Strontianite from Celestite Ore

Strontium carbonate (SrCO3) is one of the most important strontium compounds that have been used in a variety of technological and industrial applications. It is particularly used as an additive in the fabrication of glass cathode-ray tubes for TV and computer monitors (more than 65% of total production) and as a constituent of magnetic ferrites (more than 20% of total production). Other applications are in the manufacturing of special glasses, in pyrotechnics, paints, medicine and photocatalysts such as strontium titanate and zirconate for aqueous degradation of organic pollutants and advanced ceramic materials. Although SrCO3 occurs naturally as mineral

strontianite, most of it that is available has been produced from celestite ore (SrSO4) that is the only commercially exploited strontium mineral.

There are two commercial processes to manufacture SrCO3 from celestite; the black ash and the double decomposition (direct conversion) processes. In the black ash process, SrSO4 is reduced with coke (or coal) at temperatures generally over than 1000 °C to produce water soluble SrS. The sulfide is then leached in hot water and strontium carbonate is precipitated using soda ash, ammonium bicarbonate and/or CO2 . In the second process, finely powdered celestite is reacted with hot sodium carbonate solution (>90 °C) to obtain SrCO3 and by-product sodium