Behavioral mechanisms of charcoal in oxygen-free copper melting and casting
Charcoal consists of four parts,which are moisture,volatile matter,fixed carbon,and ash.Charcoal plays a key role as a covering agent in the preparation of oxygen-free copper.To optimize the treatment and usage conditions of charcoal,the role of charcoal in the melting and holding process of oxygen-free copper was explored.The micro-morphological and compositional variations of charcoal under different pretreatment conditions were investigated.The results showed that when the pretreatment temperature and time of 500 ℃-5 h,and 550 ℃-4 h,the water and volatile matter in the charcoal could be effectively released and the loss of fixed carbon was minimized.The ash in the charcoal reacted with the copper solution and phosphorus copper to form compounds such as Cu2O and calcium cop-per phosphate(Ca3Cu3(PO4)4),resulting in copper and phosphorus loss.In the study on the thickness of charcoal cover,when the thickness of charcoal was 15-20 cm,the mass fraction of carbon in oxygen-free copper ingots was lower than 0.002％,the mass fraction of oxygen was lower than 0.000 5％,and the ingot defects were minimized with the highest material utilization.
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