STUDY ON SURFACTANTS USED FOR PASSIVATION OF NATURALLY OCCURING CARBONACEOUS MATTER IN GOLD BEARING ORES

*Stamen S. Dimov and Brian Hart

Surface Science Western, Western University

999 Collip Circle, London, On, Canada N6A 5B7

(*Corresponding author: )

ABSTRACT

The naturally occurring carbonaceous material (CM) in gold bearing ores often exhibits strong-preg-robbing properties and can adversely affect the process of gold recovery during the cyanidation due to its ability to adsorb, or preg-rob gold from the cyanide leach solution.

In order to minimize gold losses due to preg-robbing, various measures could be employed, such as (partial) removal of the carbonaceous material by flotation separation, adding an activated carbon in the cyanide circuit (CIL) or passivating (blinding) of the naturally occurring carbonaceous material prior to the cyanidation process by using various chemical surfactants. Removal of the carbonaceous material is often ineffective due to the presence of this material as disseminated carbonaceous particles, i.e finely disseminated carbon on the surface of various gangue and/or value added particles which are not easy to float or can be inadvertently partitioned to leach recovery streams.

Treatments of carbonaceous ores with chemical surfactants have shown promising results but at the same time have demonstrated that, if not properly used, it could have a strong detrimental effect on the gold recovery process. High dosages of surfactants used as passivating agents for carbonaceous matter could lead to unwanted partial passivation of the activated carbon added during the CIL process and severely impact the gold recovery. Optimal dosage for various surfactants would strongly depend on the ore mineralogy and the parameters of the pulp (temperature, pH, surface area and maturity of the carbonaceous material, etc.).

This paper describes an experimental study on various commercially available blinding agents used to minimize the preg-robbing capacity of naturally occurring carbonaceous matter. The scope of the study was to: i) characterize the CM in the ore, ii) establish the optimum addition of masking agent (surfactant) to minimize the preg-robbing capacity of the CM in the ore and iii) to establish maximum threshold amounts of masking agents to be used before it negatively impacts the preg-robbing capacity of the activated carbon used in the CIL process. The study procedure involves standardized doping tests for evaluation of the maximum preg-robbing capacity of treated CM and parallel surface analysis by TOF-SIMS to monitor the loading of these chemical surfactants on both the naturally occurring CM and the added activated carbon.

KEYWORDS

Gold recovery, carbonaceous matter, preg-robbing, masking agents