In 1894, Johnson patented the proce

In 1894, Johnson patented the process of gold recovery using wood charcoal from a cyanide leached solution, but it was not until the early 1950’s that Zadra et al. from the US Bureau of Mines developed the activated carbon based technology (Johnson, 1894; Zadra et al., 1952). The relative ease at which gold adsorption takes place onto activated carbon and the subsequent desorption has generated significant interest from both the scientific and industrial fields. In particular, the gold mining industry has effectively used activated carbons to extract gold (Au) from crushed ore to maximise extraction rates for many years and hence reduce processing costs. There are two activated carbon based technologies that are widely used in the gold industry, the first is carbon in pulp CIP) process and the second is carbon in leach (CIL) process. Both technologies use activated carbon with an approximate surface area of 1000 m2/g produced from peat or coconut based carbon. This activated carbon is then used for the adsorption of Au (I), which is in the form of Au CN 2- ions that are present in the cyanide leach liquors that normally contain around 10 mg/L of Au (I) (Marsden and House, 1993). Once the activated carbon is loaded with the Au (I) complex, it is separated from the pulp by screening, and then washed. It is then stripped of the Au complex in a hot caustic solution.This is followed by the electrowinning of the Au from the concentrated Au (I) solution and the recycling of carbon (reactivation). After regeneration (reactivation) cycle the carbon is ready for another Au loading process again, with this process continuing until the carbon material becomes unserviceable. The low capital and operating costs, in conjunction with the high selectivity of activated carbon towards Au, has made both the CIP and CIL processes a very attractive economical option for the gold industry (Muir,1991; Fleming, 1998). This is clearly evident from the increase in annual carbon-based global gold production from 0% in the 1970s to 70% in 2000 (Fleming et al., 2011).