Study On The Salt Making Process Of Concentrated Brine Electrodialysis From Seawater Desalination

As an important part of water resources, the effective utilization of the seawater is one of the important ways to solve the shortage of water resources in our country.Mature technology of seawater desalination gave rise to the desalination project construction, and it ease the water stress of coastal areas especially the rapid economic development of the coastal city to a certain extent. High concentration of by-product seawater will have influence in ecological environment of the closed area in the large-scale desalination project construction. According to the circular economy development plan and Marine ecological environmental protection requirements,concentrated seawater utilization technology research will be a prerequisite for the water resources development and utilization.As efficient membrane separation technology, electrodialysis is one of the effective methods of selective separation of electrolyte ions, has been widely used in foreign countries. In recent years, the application of electrodialysis technology in salt industry has made certain research progress in the domestic, but still did not see report for industrial application.With discharge of a certain power plant of 5.4 oBe' concentrated sea water as the raw material, this paper studies the process of the purification of the concentrated seawater, evaporation and concentration, electrodialysis, salting, potassium and producing low sodium salt, etc and the feasibility of it's industrialization. It found that after desalination by electron-osmosis membrane module, the selective of permeability monovalent ions is very good such as Na+, K+, Cl-. When controlling of the desalination rate 80%,the concentrated brine salinity is 20% or higher,Including that NaCl?200g/l, KCl?6g/l; concentrate water is 15.5% of the amount of raw materials, enrichment recovery: NaCl ? 80%, KCl ? 85%, the electrodialysis energy consumption?40kw·h/m3. In the concentrated brine in evaporation crystallization process, the refined salt precipitate out during 108.5 ?and the recovery rate is 60%; the ending temperature of concentrate evaporation is 115 ?, NaCl crystallization precipitation rate?97%,after dehydration refined salt NaCl?99.1%;the cooling crystallization temperature is 25?,KCl crystallization precipitation rate ?60%,refined KCl products KCl?99.1%; low temperature vacuum evaporation is 0.098 MPa,the terminal temperature of solution evaporation is 42?, low sodium salt products NaCl?68%, KCl?30% and the impurity content of salt<1%; evaporation crystallization mother liquor NaCl?2% ? KCl?3.5%, the extraction yield of the concentrated seawater is NaCl ?80%?KCl?85%, higher than that of saltern salt water utilization.The refined salt products at the market price is about 350 ?/t, so the study on the salt Making process of concentrated brine electrodialysis from seawater desalination has production industrialization application value.