Study Of Physical And Chemical Properties Of K、Li-enriched Aluminum Electrolyte

Sustained development of aluminum industry needs to develop new technology of aluminum reduction which could save energy and reduce pollution. Electrolyte with good physical and chemical properties is the basis of the application of new technologies. Founded by National High Technology Research and Development Program(863program:2008AA030503), combined with the feature that potassium salt and lithium salt coexist in industrial aluminum electrolyte investigated the liquidus temperature,alumina solubility and density of Na3AlF6-5%CaF2-2%MgF2-3%Al2O3-x%AlF3-y%K3AlF6-z%LiF melt. The main results of the investigation are summarized as follows:(1) The addition of K3AlF5and LiF is helpful to reduce the liquidus temperature of Na3AlF6-CaF2-MgF2-Al2O3-AlF3-K3AlF6-LiF melt,and the potassium and lithium salt influence the liquidus temperature in common. When the content of AlF3is11%and the content of LiF is1%and0%respectively in the melt, KR increases from3%to12%and the liquidus temperature is decreased by26℃and27.4℃respectively。When AlF3content is11%, KR is6%and0%respectively, and LiF increases from0%to4%, liquidus temperature is decreased by25.8℃、31.2℃。(2)K3AlF6is helpful to improve the alumina solubility in industrial aluminum electrolyte, and the addition of LiF could decrease the alumina solubility in electrolyte。At925℃, when the content of LiF is1%and AlF3content is13%, KR increases from6%to12%and alumina solubility increases from5.41%to5.87%. When KR is9%and AlF3content is13%, LiF increases from1%to4%and alumina solubility decreases from5.72%to5.02%. When LiF content is3%, KR is6%, and AlF3content is9%, superheat degree increases from10℃to22℃and alumina solubility increases from5.06%to5.29%(3) The density of Na3AlF6-CaF2-MgF2-Al2O3-AlF3-K3AlF6-LiF melts decrease with the increasement of the content of K3AIF6and LiF. At940℃, in the melts which LiF content is3%, KR increases from3%to 12%, and the electrolyte density decreases from2.173g·cm-3to2.079g·cm-3. At950℃, in the melts which KR is6%, the content of LiF increases from1%to4%, and the electrolyte density decreased from2.159g·cm-3to2.114g·cm-3.