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 Na

2

SO

4

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.