Study On The Purification And Decoloration Of Salt Lake Brine

In recent years,the development of salt lake industry and its production extension brings about some problems.Take Yuncheng and Qinghai salt lakes as examples,firstly,with the utilization of the saline lake,Yuncheng saline lake brine is abundant in complex organic materials gradually,which not only deepened the brine color,but increased the viscosity.The high chroma will affect the purity and quality of the brine products.Secondly,as the imbalancing exploitation proceeds in Qinghai salt lake,camallite becomes inferior and calcic,magnesian and natrium impurities increase gradually. Calcium sulphate reaches 6%(w/w) in camallite.A great deal of materials in brine is wasted.With the establishment of the concept of sustainable development and demants of a resource-conserving society,pattern of salt lake industry turns from extensive into refine.As one of the primary contents in the saline lake industry,the significance of brine purification and decoloration becomes more and more notable.The cause of the brine chroma in Yuncheng salt lake,purification methods such as adsorption by granule active carbon or D101 resin were tested. Additionaly,H₂O₂ was used to decolorize the brine by oxidation. Furthermore,the form of calcic impurity in brine from Qinghai salt lake was examined;experiments of carboxylic cellulose and SL- depressor to remove calcium sulphate were also carried out.Results show that,the main color causing material in the brine from Yuncheng salt lake is organic matters,judged by analysing chromatogram, ultraviolet scan and so on.The optimum conditions of particle activated carbon adsorption are as follows:6g PAC/50mL brine,pH = 2,temperature 90℃,adsorption duration 9h.The decolorizing rate reached 70%under such conditions.The optimum conditions by D101 macroporous resin adsorption are as follows:10mL resin / 100mL brine,pH = 2,60℃,adsorption duration 10h.The decolorizing rate reaches 60%,relatively lower than that of granular activated carbon.The result of H₂O₂ oxidation show that decolorizing rate can reach 60%under the optimum conditions as pH 2,m(hydrogen peroxide):m(bittem) 3:100,temperature 40℃,mixing 2h.But by combination treatment of adsorption and oxidation,the decolorizing rate increases to 84%;and the treated bittern meet well with the demand of industry utility.Brine used as salt industrial material is mainly from among the crystal lattice in Qinghai area.Calcic impurity in the brine consists of resolvable calcium ions mostly,and together with a little calcium sulphate.It was found that Ca²⁺ would improve KC1 recovery when its concentration increases up to 1.5%(w/w);while it would depress the recovery when the concentration is beyond 1.5%,because of its competition with KC1.The quality of KCI would be severely deteriorated by calcium with lowering KC1 purity.And Ca²⁺ would compete with KC1 for the captor.Carboxylic cellulose and SL-depressor were utilized to remove calcium sulphate in this paper.The optimum conditions are as follows:40mLN₂/min,100r/min,0.0005g octadecylamine/g KC1,0.1g depressor/g CaSO₄,and with the addition of depressor and followed by the captor,the recovery of KC1 would increase from 85%to 90%.