Effect of demineralization and activation conditions on properties of active carbon frm waste coals

摘要

Active carbon pellets 5-10 mm in diameter have been prepared from waste of high and low rank coals. Coals samples were carbonized and activated using steam in a rotating drum at temperatures up to 1000 deg C. Demineralization and pelletization processes were separately carried out prior to or after steam activation. An experimental prototype scale study was carried out using a horizontally mounted and perforated rotating drum, made of NiCr and rotates at a variable speed up to 100 rpm for periods up to 4 hours. The effect of demineralization and activation conditions on the physico-chemical properties of the prepared active carbons was determined. Results obtained show that active carbon pellets having 1250 m~2/g with 5percent ash and good mechanical properties are prepared. Surface area and porosity values increase passing through a maximum with burn-off, rotation speed of the drum, flow rate and pressure of steam, temperature up to 900 deg C and time. Development of macropores takes place satisfyign the collapse of the micro and mesoporous system. Demineralization before activation was more effectve than if the process was carried out after activation. Inorganic impurities retard the carbon burn off and decrease the surface area. Pelletization of active carbon slightly decreases its adsorptive capacity and this was ascribed to surface poisoning. natural molasses was found a suitable binder in terms of surface and mechanical properties. The product is found suitable for copper, nickel and chromium recovery from spent electrolyte of printed circuit and electroplating industries