Functional failure analysis of the graphite crystallizer used in horizontal continuous casting process of copper tube

The presence of a particular type of white powder has emerged as a significant challenge in the horizontal continuous casting process of copper. This white powder leads to the blockage of the graphite crystallizer, resulting in a functional failure that adversely affects the mold's lifespan, increases production costs, and reduces overall efficiency. The issue has posed significant challenges for engineers due to its complex and unclear formation mechanism. This investigation employed various experimental characterization methods to analyze the composition, element distribution, phase properties, and other relevant factors of the white powder. Meanwhile, a high- temperature experiment was also designed to examine the potential reactions between copper oxide (Cu2O) and the furnace lining (3Al2O3 & sdot;2SiO2). It is found that the main component of the white powder blocking the inlet hole of the graphite mold is SiO2, which is traced back to the furnace lining. Under high temperatures, oxygen reacts with liquid copper to form Cu2O. Subsequently, this Cu2O reacts with Al2O3 in the furnace lining to produce CuAlO2. Meanwhile, SiO2 becomes isolated as Al2O3 is deprived. The resultant SiO2 accumulates at the inlet hole of the graphite mold due to rapid cooling. The accumulated SiO2 in the form of white powder blocks the inlet hole of the graphite mold, leading to functional failure of the graphite mold. To address this issue, several improvement measures are proposed including drying the raw and protective material, enhancing the sealing of the furnace, and reducing the holding time.