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A quantitative study into carbon-in-pulp adsorption operations
Author(s)
Gray, Diane Elizabeth
Date Issued
1999
Type
Thesis
Publisher
Cape Technikon
Abstract
Carbon-in-pulp (CIP) and carbon-in-leach (CIL) remain the most effective, and widely used
processes for gold recovery from cyanided pulps. The extensive use of carbon in such
processes have prompted many researchers to investigate the mechanism of metal cyanide
adsorption. Not only has this provided many viable theories in the understanding of the
mechanism, but it has also led to an improved understanding of the effects of the various
operating conditions on the CIP circuit. However, the declining gold price has made gold
producers aware of the need to either further optimise existing circuits or find alternative means
of operation so as to improve efficiency. It is therefore the aim of this study to investigate the
factors which influence the metal extraction circuit.
In this study the effects of parameters such as gold and carbon concentrations, slurry density
and stirring speed on the adsorption process were investigated. It was found that the effects of
gold and carbon concentrations could be determined directly, that is, a definite linear
relationship exists between these two parameters and adsorption rate. However, slurry density
and stirring speed (power input) have a twofold effect on the process. For this reason two
distinct terms called the "blinding" and "mixing" numbers have been identified. It has been
shown that all the parameters investigated influences the rate of adsorption during the constant
rate adsorption period. However, only solution concentration, carbon concentration and carbon
loading influence the process during the diminishing rate of adsorption. This confirmed the
belief that intraparticle diffusion is the rate controlling factor during the diminishing rate
period. Furthermore, the point at which constant rate adsorption is replaced by the diminishing
rate of adsorption is mainly a function of solution concentration.
processes for gold recovery from cyanided pulps. The extensive use of carbon in such
processes have prompted many researchers to investigate the mechanism of metal cyanide
adsorption. Not only has this provided many viable theories in the understanding of the
mechanism, but it has also led to an improved understanding of the effects of the various
operating conditions on the CIP circuit. However, the declining gold price has made gold
producers aware of the need to either further optimise existing circuits or find alternative means
of operation so as to improve efficiency. It is therefore the aim of this study to investigate the
factors which influence the metal extraction circuit.
In this study the effects of parameters such as gold and carbon concentrations, slurry density
and stirring speed on the adsorption process were investigated. It was found that the effects of
gold and carbon concentrations could be determined directly, that is, a definite linear
relationship exists between these two parameters and adsorption rate. However, slurry density
and stirring speed (power input) have a twofold effect on the process. For this reason two
distinct terms called the "blinding" and "mixing" numbers have been identified. It has been
shown that all the parameters investigated influences the rate of adsorption during the constant
rate adsorption period. However, only solution concentration, carbon concentration and carbon
loading influence the process during the diminishing rate of adsorption. This confirmed the
belief that intraparticle diffusion is the rate controlling factor during the diminishing rate
period. Furthermore, the point at which constant rate adsorption is replaced by the diminishing
rate of adsorption is mainly a function of solution concentration.
Additional information
Thesis (MTech (Chemical Engineering))--Cape Technikon, Cape Town, 1999
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