The comprehensive utilization and environment-friendliness of processes for recovering fresh water or valuable salt from seawater, salt-lakes, or mineral deposits are of utmost importance for sustainable development. One primitive sustainable process for recovering salt from sodium-sulfate-type brine in Yuncheng salt lake had been considered one of the greatest inventions of ancient China, however, the replaced process of mass extraction of single Na2SO4 in recent years, has reduced a large amount of residual brine. In this research, relying on the salt-forming diagram in the non-equilibrium state, the technical secrets of ancient salt processes were uncovered, and a new comprehensive utilization system was proposed and tested experimentally. The new system includes a vacuum salt-making process and a normal pressure kieserite process, which can gradually eliminate the existed waste liquid and aid in the sustainable development of the Yuncheng salt-lake. The continuous experiment of salt-making process running stably in the double salt region without double salt formation, which proves the feasibility of salt-forming diagram applied in industrial process. Thus salt-forming diagram would be extremely valuable to industry process design and control, especially, the treatment of concentrated brine. (C) 2018 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.