The leaching of SrS with water and the precipitation of SrCO3 from leach solution by different carbonating agents

The leaching of strontium sulfide (SrS) with water was investigated, and a comparison of Na2CO3 with CO2 as a carbonating agent for the precipitation of SrCO3 from leach solution was done. The effects of variables for leaching-temperature, retention time and solid to liquid ratio, and the effects of variables for precipitation-carbonation time, temperature, amount of carbonating agent and addition of oxygen to carbon dioxide, were studied. It was concluded that leaching of strontium sulfide is mainly dependent on the solubility of strontium hydroxide; however, SrS decomposes easily in hot water to give the hydrosulfide and the hydroxide. As a carbonating agent, Na2CO3 provides higher precipitation rates and higher strontium recovery but low SrCO3 grade, whereas precipitation with CO2 gives a high purity of product which is sufficient for most of the uses of SrCO3. It was also found that oxygen, when used together with carbon dioxide in the carbonation column, increases the strontium recovery and decreases the carbonation time. (C) 1998 Elsevier Science B.V. All rights reserved.