Field Test Results of a Nanofiltration Application for Separating almost Saturated Brine Solutions of the Vacuum Salt Production

To produce vacuum evaporated salt from a salt feedstock in high purity a high amount of mother liquors has to be purged which causes a loss of salt and repre- sents a big environmental problem. A solution is seen in a selective recycling of sul- phate ions from the mother liquors back to the brine treatment. Laboratory tests have shown that a NF process would offer a new way in the salt winning technology if this technique can be successfully applied within the salt production. To investigate the feasibility and the usefulness, pilot tests were carried out at the Austrian Salt Works in Ebensee. The investigation was conducted over a period of 9 months with an automated 25 m2 membrane separation plant in which data on the membrane per- formance and stability were collected. The field tests have proven the membrane process to be a satisfactory and technically feasible application.