Activated Carbon Prepared in a Novel Gas Fired Static Bed Pyrolysis-Gasification Reactor for Gold Di-Cyanide Adsorption

Abstract

A novel gas fired static-bed pyrolysis-gasification/activation reactor has been designed. A special feature of the reactor is its rectangular cross-section, having a square groove positioned symmetrically at the bottom part of the reactor, which allows efficient heat transfer into the bed of material being pyrolysed. The reactor is designed also to allow easy feeding of precursors as well as easy discharging of carbonised products. The operating parameters of the reactor such as temperature, which is dependent on the fuel gas flow rate; and the rate of flow of steam into the reactor for gasification, can be monitored. Palm kernel shells based activated carbon was prepared by carbonisation of the shells at 900 ºC pyrolysis temperature, followed by steam activation of the derived char also at 900 ºC for 6 hours. Activation was done at steam addition rate of 0.2 mol/h/g in the reactor. The derived activated carbon was characterised using the hard groove test method and the carbons were found to possess relative hardness comparable to the commercial one in use in some gold processing companies. The gold di-cyanide adsorption characteristics of the derived activated carbon compared very well with that of the commercial activated carbon, Norit RO 3515 used in most mines in Ghana.

Keywords: Pyrolysis, Gasification, Activated carbon, Gold processing, Adsorption