CaC2 Production from Pulverized Coke and CaO at Low Temperatures-Influence of Minerals in Coal-Derived Coke

Compared to the traditional electric arc process for the production of CaC2 from coke and CaO, the autothermal process requires less energy. However, the coke used for in situ heat generation results in more minerals in the reactor, because of the presence of minerals (or ash) in coke. This paper studies the influence of minerals (Fe2O3, MgO, SiO2, and Al2O3) commonly found in coal-derived coke on the formation of CaC2. The effect of CaF2, which is an additive used in some of the electric arc processes, on CaC2 production is also evaluated. The results show that Fe2O3 and MgO have little influence on CaC2 formation. SiO2 and Al2O3 do not react with coke at temperatures lower than 1460 degrees C, but they do react with CaO to form Ca3SiO5 and Ca2Al2O5, respectively, or calcium aluminosilicates in the presence of the both. All these Ca-containing compounds are able to react with C to form CaC2 but at rates lower than that of CaO and consume more C (to form CO). CaF2 has little influence on CaC2 formation in terms of mass change and CO formation, but promotes decomposition of CaC2 into Ca and C. The use of coke with low SiO2 and low Al2O3 is important for CaC2 production for lower coke consumption.