CALCIUM CARBIDE POWDER INJECTION INTO HOT METAL .1. HEAT-TRANSFER TO PARTICLES

Calcium carbide powder was injected into an induction furnace containi ng 70 kg of carbon saturated iron to understand the transport phenomen a associated with desulphurisation. In Part 1 of this two part paper, the thermal aspects of injection are addressed. The melt temperatures were measured before, during, and after the injection of gas alone and gas and calcium carbide particles. A heat transfer analysis of the re sults was carried out. Without injection, most of the heat was lost to the water cooled coil. During gas injection, the first order rate con stant for bath cooling increased linearly with gas flowrate. During po wder injection, heat transfer to the particles caused much greater add itional heat losses from the melt, but only 30-50% of that expected if the particles were heated to the melt temperature. It was concluded t hat this corresponded to the percentage of the particles contacting th e melt; the remaining particles were transported to the bath surface b y the carrier gas bubbles. At solid-gas loadings below 60 kg/Nm-3, onl y 30% of the particles contacted the melt, whereas above this loading the contact increased to 50%. This transition was attributed to a chan ge of flow regime from bubbling to jetting. In Part 2 (this issue) the kinetics of simultaneous desulphurisation and deoxidation is addresse d.