Potassium sulfate-A precious by-product for solar salt works

摘要

In salt production from sea water,water is evaporated in open ponds and common salt(NaCl)is crystalized and harvested.At the end of sea salt production usually large quantities of high salinity brines,so-called bittern remains.Discharge of that bittern can lead to significant environmental challenges.Furthermore,but not less important,bittern contains a large amount of valuable minerals.To describe how to process sea bittern further to recover and extract these valuable minerals and convert them into precious by-products is the prime objective of this paper.The present work will focus on the production of potassium fertilizers and in particular potassium sulfate as an especially attractive by-product of seasalt production.The paper describes all essential process steps required to produce potassium sulfate(K2SO4)and potentially other valuable downstream products.Finally,some project examples and an economic assessment are given to underline,that processing of bittern is not only getting more and more important because society and companies are focused increasingly on environmental protection.In fact,it is shown that extracting valuable by-products out of bittern can be a very economically attractive option to diversify production and create additional input streams for sea salt works with a production capacity of above one million tons of common salt per year.