VOLATILIZATION BEHAVIOR OF MINOR ELEMENTS DURING NON-ISOTHERMAL OXIDATION OF COPPER CONCENTRATE PARTICLES FALLING IN ONE-DIMENSIONAL LAMINAR GAS FLOW

摘要

Copper concentrate particles of 200 to 300 mesh size were fed from the top of vertical reaction tube of 2.8 cm ID and 2 m long with an O_2-N_2 gas mixture. The reaction tube was heated to 900 K to 1100 K. The residence time of the particles in the reaction tube was about 1 second. The copper concentrate particles were very rapidly oxidized and melted down during their descent in the reaction tube. The particle temperature were calculated by combining an un-reacted core model, mass transfer between gas and particles, and heat transfer between gas, particles and tube wall. The particle temperature reached its maximum within a distance of 60 cm from the top of reaction tube, and it attained at 2000 K at higher oxygen partial pressure. The most particles were melted at the oxygen partial pressure above 20 kPa. An appreciable amount of As, Sb and Pb in the concentrate particles was eliminated in the upper portion of the reaction tube and the rate of elimination are explained by the rate of mass transfer of volatilized species through the gas film on the particle surface and the variation of particle temperature during the descent.