Removal Mechanism Of Micro/trace Impurities From Electronic Grade Copper Scrap By Rotary Segregation Enhancemen

Traditional directional solidification has the characteristics of“long solidification time and complex solidification process”,which brings serious defects to its structure.The main quality problems of ingots obtained by directional solidification are coarse grain structure and severe macro segregation of components.Both of these problems are closely related to the“temperature gradient”and“convective motion”conditions during solidification of large ingots.This study is aimed at directional solidification,based on rotational segregation technology,and studies the effects of temperature field,flow field distribution,and different process parameters on impurity removal and crystal growth of molten steel in the tundish at different rotational speeds.The research results provide a reference for theoretical research on impurity removal by rotational segregation directional solidification.The research results are as following:(1)The results of thermal simulation experiments on large ingots with rotational segregation show that the temperature gradient during solidification seriously affects the grain morphology and size.Different temperature gradient conditions can change the dendrite length.The temperature gradient during solidification can also affect the flow field changes and affect impurity removal.The higher the rotational speed,the better the impurity removal effect.The best impurity removal effect in this experiment is at 200 r/min.(2)During the solidification stage,adding a cooling body for rotation will cause forced convection to refine the solidification structure.As the rotational speed increases,the average length of columnar crystal growth begins to decrease,from 0.197 m~2to 0.053m~2.With the increase of rotational speed,the microstructure increases significantly.The corresponding cross-sectional image of the copper ingot conforms to its solidification law.We can find that forced convection affects crystal growth more than temperature,and forced convection can lead to refinement of the solidified structure.Severe stirring in the molten pool is beneficial to the formation of equiaxed crystal structures.(3)Using a self-made rotary segregation smelting furnace can achieve the removal of extremely low impurities in high purity copper.This equipment is suitable for the production of various metals and alloys.This method provides a new approach for the preparation of high purity metals and their alloy materials,and is expected to achieve the unity of crystal growth and collaborative impurity removal.