MANUFACTURE OF METALLIC SULFATE BY ION EXCHANGE

摘要

This invention relates especially to the production of potassium sulphate which is used primarily as a specialty fertilizer. The process presented here uses ion exchange to combine soluble sulphates such as sodium sulphate with potassium chloride to produce a low chloride ion containing potassium sulphate product which is desirable for agricultural and industrial markets. In particular, in the preferred mode of ion exchange, an anion exchange resin is loaded with sulphate ion using sodium sulphate. The sulphate laden resin is then treated with potassium chloride brine from a recycle stream. The exit brine containing potassium sulphate and potassium chloride is treated with potassium chloride to salt out the bulk of the potassium sulphate which is then separated or filtered off. The mother liquor which is rich in potassium chloride is available for another production cycle. In the regeneration cycle, the exit regeneration brine containing sodium chloride and sodium sulphate is treated with solid sodium chloride to salt out the sodium sulphate for separation and recyle to the regeneration step. Dilute sulphate brines can also be used for regeneration.