Optimization of extraction of bromine - order elements
Our country has already become one of the world's fastest-growing regions seawater desalination, concentrated seawater desalination discharge is chemical resources, a large quantity of high quality, if its emissions is not only wasteful, bromine will harm the coastal environment. In the recently held 2012 Qingdao International desalination conference, experts suggest, for the comprehensive utilization of concentrated seawater, should change the traditional process of salt, by optimizing the elements are extracted from the sequence and varieties, improve the added value of the products, in order to diluted cost, eliminate bottlenecks desalination facing the high cost.
Reporters learned that, as the scale of the scale of China's desalination device continues to expand, in the effective mitigation of water resources crisis, but also produced a large number of concentrated seawater. Due to the dilution of salinity and temperature and natural seawater difference is large and contains sterilization, scale, precipitation, flocculation agent, such as a large number of long-term discharged into the sea will make part of the ocean water changes, and destroy the ecological balance in the ocean, cause difficult to repair the ecological environment problem. Therefore, to solve the problem of disposal of concentrated seawater desalination has become the urgent need to discharge to overcome the difficulties. In February 2012, the State Council issued the "opinions on accelerating the development of the industry of seawater desalination" clearly put forward, the combination of seawater desalination treatment and resource comprehensive utilization.
At the same time, the chemical mineral resources in the sea water is very large. Among them, the total reserves of potassium, lithium, uranium is the total amount of the total resources of the land to tens of thousands of times, and the world's Bromine resources are almost all stored in the sea water. Seawater desalination the concentrations of the chemical components in the by-product of the concentrated seawater is nearly 2 times the concentration of standard seawater, if access to the same chemical resources, concentrated seawater treatment capacity is only for the deal directly with half of the volume of water, significantly reduce the extraction cost. In addition, using concentrated seawater chemical resource extraction without need to set water and chlorine disinfection, pretreatment equipment can greatly save the investment and the cost of the project. The temperature and flow parameters of the concentrated seawater generated during the operation of seawater desalination are stable, which is convenient for the stable operation of the chemical resource extraction process.
The State Oceanic Administration Tianjin seawater desalination and comprehensive utilization research institute researcher Zhang Jiakai think, seawater desalination plant comprehensive utilization, if the traditional sun salt and bittern comprehensive utilization process, sodium chloride utilization rate of less than 40%, potassium chloride, bromine, magnesium chloride, magnesium sulfate with rate of less than 30%. On the extraction of the chemical elements in the concentrated seawater, bromine manufacturers to revolves around the extraction of product quality and technical economy, the optimal extraction order by. He proposed the concentrated seawater macroelements in the optimal extraction sequence: first will dilute brine extract bromine bromine extraction mother liquor by using light burned dolomite extraction of magnesium hydroxide, magnesium solution by evaporation and concentration of calcium sulfate was extracted, and then secondary provided magnesium and calcium, the zeolite ion exchange adsorption of potassium ion in the mother liquor to achieve liquid salt product standards. At the same time, potassium rich liquor after elution from evaporation and cooling process of vacuum salt and fertilizer products.