Study On Non-flux Purification Behaviour Of Inclusions In Magnesium Melt

Currently, as the lightset commercial metal structure material, magnesium alloyhas the very good application prospect in many fields. Purification of magnesium meltis one of the key working procedures in magnesium alloy casting production and wasteregeneration, and has a significant impact for ensuring product quality and perform-ance. Now the general use of purification of magnesium melt is flux method in indu-stry, but existing some questions of producing toxic or harmful gases and secondarypollution and so on. According to the above problems, this paper takes a new non-fluxpurification technology as an object, some experimental studies are carried out for itsbased issues, aim to provide theoretical support for the development and application ofthe non-flux purification technology.Firstly, the solid inclusions are analyzed and characterized by means of OM、SEM、EDS in the paper; and then the visual-physical simulation is carried out for newnon-flux purification process and behavior by means of the hydraulics model method;finally the experimental verification is carried out under the industrial environment.The main research work and results are as follows:1) For the smples of high-inclusion magnesium alloy, the analysis and characteri-zation results show that the morphology of inclusions in magnesium alloy mainlyinclude: granular、flocculent、clusters、rod、bulk and leather, dominated by granular andflocculent; from the point of chemical composition, the oxide inclusions are the mostcommon in magnesium, and the content is the highest.2) The visual-physical simulation is carried out for new non-flux purificationprocess and behavior by means of the hydraulics model, the results show, under theexperimental conditions, the seperation of inclusions and aqueous solution exixts somekinds of behaviors as follows: first of all, the settlement separation, namely partialheavy inclusions gradually natural subsides to the bottom of the container under theirown gravity, no longer with the solution flow, and realized the separation; second,inertia separation, that is, when the fluid flows through the baffle flow and the flowdirection is changed, patial inclusions separate due to the density difference and inertialdifference, gradually sinking to the bottom of the container; finally(the most important),self purification filter, the inclusions that is bigger than filter hole sizes are effectlyblocked and separated by means of inverse filtering technology,and these blocked inclusions will subside naturally without blocking filter holes, namely the filter mediumhas the effect of self-purification; in addition, the filter medium also can stop andcapture bubbles in the liquid, which has a certain effect of degassing.3) Under the industrial environment, using the purification furnace which is similarto water simulation experiment(same structure and amplifying size), the non-fluxpurification experiment is carried out for the magnesium scrap of high-inclusioncontent, in the process of experiment, selecting different samples in different lacationsin furnace with the flow direction of magnesium liquid, and then analize and test thesesamples:on one hand, the observation results of OM and SEM show, the high-inclusioncontent scrap magnesium by natural sedimentation, inertial separation and reverseself-purification filter, the content of inclusion becomes less and less and the sizes ofinclusions also graduallybecome smaller, the trend is especially obvious after two stagefiltering; on the other hand, the XRF results showed that O, Si and Mn element contentin the melt showed rather obvious gradual reducing trend, the content of S, Ca, Feelement is low, also has a certain gradual reducing trend, show that after the non-fluxcompound purification, the oxide、containing silicon phase、sulphide、calcifications、silicon manganese compound inclusions of the melt are effectively removed. The aboveexperimental results and the results and the laws of water simulation experiments areconsistent.At the same time,it verifies that the non-flux purification technology iseffective.In short, the above research work and results show that the inverse filtering, as thecore of non-flux purification technology, can effectively realize purification of magne-sium melt, the application prospects look good.