Process water for producing salt by means of strong brine concentration after sea water desalination by using a two-way circulation method and bromine extraction

A process for producing salt from strong brine produced from sea water desalination, comprising the following steps:

• A. preparing strong brine from sea water by a reverse osmosis method, wherein the concentration of the prepared strong brine is 7000˜80000 PPM;
• B. separating the strong brine in a two-way circulation manner by using a concentration difference method till the strong brine is crystallized, wherein the two-way circulation manner by the concentration difference method includes the following steps:
• a. setting several 12 m deep brine tanks and numbering them:
• I-XVII, in which:
• every brine tank is divided into three areas, among which an upper 4 m is a low salinity area, a middle 4 m is a medium salinity area and a lower 4 m is a high salinity area;
• each area of the brine tanks are separated by a concentration difference of 0.2˜1.5°, and a concentration difference of the same area of neighboring brine tanks is 1˜3°;
• the brine tanks I-XVII are divided into salt areas with brine concentrations ranging from 4˜29°;
• and the brine tanks I-XVII generally decrease in brine concentration;
• b. injecting the strong brine with the concentration of 7000˜80000 PPM 6 m deep into brine tank XV having a concentration of 7° in the medium salinity area;
• c. pumping the brine at a bottom of every brine tank into the medium salinity area of an adjacent brine tank having higher salt content, and the brine of low concentration at a top of a brine tank having higher salt content will overflow to an adjacent brine tank having lower salt content, forming a two-way circulation;
• d. extracting sodium chloride crystals in a strong brine area at 27˜29° after a crystallization of sodium chloride at around 29°.