Binding waste anthracite fines with Si-containing materials as an alternative fuel for foundry cupola furnaces

An alternative fuel to replace foundry coke in cupolas was developed from waste anthracite fines. Waste anthracite fines were briquetted with Si-containing materials and treated in carbothermal (combination of heat and carbon) conditions that simulated the cupola preheat zone to form silicon carbide nanowires (SCNWs). SCNWs can provide hot crushing strengths, which are important in cupola operations. Lab-scale experiments confirmed that the redox level of the Si-source significantly affected the formation of SiC. With zerovalent silicon, SCNWs were formed within the anthracite pellets. Although amorphous Si (+4) plus anthracite formed SiC, these conditions did not transform the SiC into nanowires. Moreover, under the test conditions, SiC was not formed between crystallized Si (+4) and anthracite. In a full-scale demonstration, bricks made from anthracite fines and zerovalent silicon successfully replaced a part of the foundry coke in a full-scale cupola. In addition to saving in fuel cost, replacing coke by waste anthracite fines can reduce energy consumption and CO₂ and other pollution associated with conventional coking.