The Research On Utilization Of Potassium In Deep Brine Of The Heibei Concave In Qaidam Basin

In recent years,a large amount of new type pore brine in the sandy gravel layer has been found in the western Qaidam basin.After preliminary analysis,the brine in the Heibei Concave area proved to have high degree of mineralization(generally between 280-300g/L),and a single chemical composition.The KCl grade is generally more than 0.30%.It is not easy to produce salt in the brine extraction process and easy to exploit,which can be used as an alternative area for the subsequent development of potassium salt.In order to realize the comprehensive utilizations of this brine,it is particularly important to carry out related researches.In order to obtain the crystallization process of potassium in the new tape brine,natural evaporation experiment of the brine from Heibei Concave was carried out for the first time.The sequence of mineral precipitation in the evaporation crystallization process was halite,carnallite,and brucite.According to the identification of salt and the analysis of material balance,potassium is precipitated in the form of carnallite,the content in the precipitation stage is between 19.35%and 46.85%.Li,B₂O₃were enriched in the whole evaporation process.Considering the analysis of evaporation process,the enrichment regularity of ions in brine is closely correlated with the changes in p H and density,similar to that of the salt precipitation.The results of salt field are basically same as the results of the natural evaporation experiment.However,due to the long process of halite in the evaporation of brine in the salt field,a large amount of halite is deposited in the sodium salt pond,and carnallite is stored as an intercrystalline brine in the halite crystal layer.By continuing to evaporate in the field,crude carnallite can be obtained,and the content is about 28.16%.For the better precipitation of carnallite,it is particularly important to study the extraction of salts,including the influence of organic solvents,salting out on the solubility of potassium salts and cold decomposition-flotation method.Carnallite can be manufactured by the method of salting-out.This to say,adding brucite or old bittern which is rich of lithium,into the saturated solution of carnallite,can promote the precipitation of carnallite.In this paper,the separation and purification test of carnallite was carried out by using the cold decomposition-flotation method.With15°C cold water and a solid-liquid ratio of 100:40,the potassium and magnesium in the carnallite mixed salt can be effectively separated.After using flotation reagent,the KCl grade of flotation concentrate was 91.25%,and the comprehensive recovery rate was 68.73%.And the test index was good,an industrial-grade potassium chloride product was obtained.Finally,the process route for the utilization of deep brine in the Heibei Concave in the western part of the Chaixi is proposed.Through salt evaporation and beach drying,the separation of sodium and potassium in the brine has been achieved.Continue to evaporate to obtain carnallite mixed salt,and potassium chloride product will be obtained through cold decomposition-flotation method.The old brine,which is rich of lithium,boron and other elements,can be used to obtain lithium,boron products by continuing evaporation.On this basis,the comprehensive utilization of the brine in the Heibei Concave can be realized.