Studies On The Salting Law Of Evaporating And Cooling The Mother Liquor Obained By Ammonia Reacting

Seawater contains almost all the chemical elements found on Earth. The brine which is the mother liquor after producing salt from seawater contains a high concentration of various minerals. The brine is so called as bittern brine. Therefore, there is a broad developing space to make an use of the bittern brine to produce many kinds of chemical product. How to make a full use of the seawater resources becomes an important issue of the utilization resource in brine.Salt chemical engineering is an inorganic chemical industry in where the chemical product was based on the resources of the brine which was produced after salt production from seawater. Phase diagram of salt-water system is the theoretical basis for separating the inorganic chemicals. The research about producing the salts from brine is usually based on the phase diagram of salt-water system. Through the analysis of brine, appropriate routing on the extraction of the chemicals from brine resources can be determined. The comprehensive utilization of brine is the ultimate goal of salt chemical engineering.The used experimental solution is the mother liquor which was obtained by ammonia reacting with the brine in this work. This paper studied the salting law of the studied mother liquor in evaporation and cooling process. The mother liquor is a complex multi-system which mainly contains K+, Na+, NH4+, Mg2+, Cl-, SO42-and other ions. There is no phase equilibrium data reporting for this system. The study of salting law about the evaporation and cooling process of mother liquor in magnesium-hydroxide production is the basic research about brine utilization. It has some role in guiding the phase diagram theory and its application.This study obtained salting law during the evaporation process for the system studied. On the basis of this salting law, the separation condition for NaCl and (NH4)2SO4in magnesium-free mother liquor was determined and the respective results was obtained. The used experimental solution was obtained by evaporating the mother liquor after NaCl production from this brine. The salting law of the solution was studied by natural cooling. The results showed that the chemicals salting out during cooling process were NH4CI and (NH4)2SO4, they were the active ingredient of fertilizer.According to the data of evaporation and cooling, the stopping point of the further evaporation of the mother liquor after NaCl separation was experimentally determined. The results defined the process conditions of separating NaCl and (NH4)2SO4in magnesium-free mother liquor. The remained high temperature clean liquor’s was further cooled to produce pure NH4CI.In order to separate Na+in the magnesium-free mother liquor, experiment was carried out with the method of putting CO2pass into the magnesium-free mother liquor. This exploratory study was not successfully to further separate Na+in the magnesium-free mother liquor, but this study still had good results on the technology for CO2capture with seawater.This work is the part of the project of "Research on the technology of comprehensive utilization of brine with ammonia method" supported by Tianjin Municipal Science and Technology Commission. This is one kind of new mentality and the method for the comprehensive utilization of seawater. The technology which is proposed in this work has the obvious function in the aspect of raising the value of seawater resources, saving energy and reducing emission, even raising the performance of enterprises.