Basic Study Of Extracting Rubidium And Cesium With Inorganic Ion Adsorbent Of KNiFC

There are many kinds of rare metal ions such as Li+, Rb+, Cs+in salt lakes, which widely distribute in Tibet. However, saline rubidium and cesium resource hasn’t been exploited and utilized till now, and there have no any published data about rubidium and cesium separation and extraction from Tibet saline either. Along with the increase of demands of rubidium and cesium products and the absence of solid rubidium and cesium mineral, saline rubidium and cesium resource has been drawing attention. It is forecasted that a quickly development period of saline cesium exploitation and utilization will come rapidly in the recent several decades.The process method of extraction of rubidium and cesium resource from the salt lake brine includes precipitation, solvent extraction and inorganic ion exchange. Taking the extraction efficiency, cost, regional environmental conditions and other aspects into account, inorganic ion exchange method is the most suitable for the extraction of rubidium and cesium. Therefore in this thesis, we studied an adsorbent---potassium nickel hexacyanoferrate (KNiFC) to separate rubidium and cesium.In this paper, we use the single factor and orthogonal test that index of assessment has been chosen by adsorption rate and desoiption rate. After considering the conditions of production and operation, the conditions of its adsorption and desorption is investigated.In this paper, the adsorption effect of rubidium and cesium is studied by four inorganic ion adsorbent which were composed under different conditions. The result shows that II (K1.48Ni1.47[Fe(CN)6]) adsorbent has the best adsorption affinity. The rubidium content is reduced from204.8mg/L to46.87mg/L and the adsorption rate of rubidium is77.11%. The cesium content is reduced from54.99mg/L to0.16mg/L and the adsorption rate of cesium is99.71%. By the conditions of adsorption of investigating experiment, we obtain the best adsorption conditions. Results are showed that:at45℃, the absorption time is4h, the added quantity is0.5g/200ml. Under such conditions, the approximate adsorption rate of rubidium is100%and the adsorption rate of cesium is99.97%.The effects of concentration of desorbed agent, liquid-solid ratio, desorbed time, desorbed temperature on desorption performance is investigated. The optimum desorption conditions for the desorption of rubidium and cesium are as follows:at55℃, desorption solution is2M NH4NO3+2M HNO3, liquid-solid ratio is400:1, the absorption time is6h. Under such conditions, the desorption rate of rubidium is74.17%, the desorption rate of cesium is53.84%.The original liquid is desorbed by two times, then the desorption rate of rubidium and cesium are82.17%and71.00%. After the desorption process, the adsorption rate of rubidium and cesium are greater than60%though the re-adsorption. But it is reduced compared to the initial adsorption.Although KNiFC, one of an ion adsorbent, has a higher adsorption effect of rubidium and cesium, it is relatively difficult to elute rubidium and cesium during the desorption process. It needs further studying on how to improve desorption rate of rubidium and cesium.