Preparation of CaO-containing carbon pellet from recycling of carbide slag: Effects of temperature and H3PO4

CaO-containing carbon pellets (CCCP) was prepared by mixing carbide slag (Ca(OH) 2 ) and powdered char to produce CaC 2 , achieving the recycling of carbide slag during CaC 2 production process. The thermal strength of CCCP was the focus of most attention when employing arc furnaces as reactors for CaC 2 production in industry. To improve the thermal strength of CCCP, H 3 PO 4 was used as a binder in this study. The results indicated that Ca 3 (PO 4 ) 2 reacted by H 3 PO 4 and Ca(OH) 2 could help refine the average particle sizes of CaO, resulted in a relatively uniform pore diameter distribution of CCCP with low porosity, therefore improving the thermal strength of CCCP. When H 3 PO 4 content was more than 8 wt%, some over-sintering and melting structure for CaO particles appear, and thus resulting in the decrease in thermal strength of CCCP. The experimental results show that CCCP with 3% H 3 PO 4 has the best thermal strength at 1100 °C. The non-isothermal shrinkage kinetics of CCCP indicated that the addition of 3% H 3 PO 4 reduced the apparent activation energy of sintering reactions and accelerated the sintering of CaO particles in CCCP. Furthermore, the addition of H 3 PO 4 has a positive effect on the formation of CaO sintered necks, enhancing the strength of CCCP.