(a) The CIP process was enabled by the development of effective elution techniques which allowed reuse of the activated carbon. Describe the chemical basis for elution methods used to recover gold from activated carbon and the effects of the four key parameters on the adsorption and desorption processes. [8 marks] (b) Describe the process of reactivation of activated carbon and list the main process parameters and conditions that can affect the activity of the carbon. [4 marks] (c) The purification of zinc electrolyte by zinc cementation is essential to the production zinc metal by electrowinning. Briefly describe the zinc cementation process using relevant block flow diagrams and explanation of the effects of key process parameters. [8 marks]