Huamei Activated Carbon received the following email from a metallurgist in Burkina Faso gold mine in 2024/11/08 asking for help:
Hello Sir! I read your article on the properties of high quality activated carbon. I am a metallurgist at a mine in Burkina Faso and we are currently experiencing serious problems with an activated coal used for gold adsorption. This carbon has a very low density and is not homogeneous in the leaching reactor. When we measure the carbon concentration in the slurry, it is always higher than we should expect. We had to mix two types of coal in the reactor, one HAYCARB and the other CO-PROCHIM, the latter being a local activated carbon and the other an imported one. As far as gold adsorption efficiency is concerned, the latter has a lower density and all the activated carbon floats on the surface, resulting in a decrease in gold adsorption activity. I would like to get some suggestions. Our treatment process is CIL and gravity method.
CO-PROCHIM activated carbon's floats on the surface in the leaching reactor, which reduces the contact efficiency with the slurry and thus affects the gold adsorption efficiency. In order to solve this problem, the following aspects can be optimised:
a. Adjust the mixing ratio of carbon appropriately
Enhance the proportion of HAYCARB: According to your description, increasing the proportion of HAYCARB in the mixture may improve the adsorption effect. It is recommended that you find the optimal ratio by first testing it in small-scale experiments and gradually increasing the proportion of HAYCARB (e.g. 70% HAYCARB + 30% CO-PROCHIM).
Adjust the ratio according to the mineral composition: different minerals have different reactivity, you can further optimise the mixing ratio according to the type of ore, the pH value of the slurry and the leaching rate of gold to ensure the optimal adsorption rate of gold.
b. Mixing method and agitation of activated carbon
Uniformity: Use suitable mechanical mixing equipment to ensure that CO-PROCHIM and HAYCARB can be evenly distributed in the slurry, to avoid CO-PROCHIM activated carbon gathering on the surface.
Adjustment of mixing rate: Increase the mixing rate or install specific mixers to ensure better distribution of activated carbon in the slurry.
a. Optimisation of the leaching reactor design
Ensure a balance between flow rate, agitation and char mobility in the CIL reactor to prevent char particles from accumulating in the reactor. Reactors with agitation or agitation tower design can be used to enhance the contact between the char and the slurry.
Dividing the CIL leaching process into multiple stages, using different char concentrations and agitation rates for each stage, may help to improve leaching and gold recovery.
b. Ensure that the contact time between the activated carbon and the gold ore slurry is sufficient during the leaching process. At the same time, increase the temperature and slurry concentration appropriately during the adsorption process to improve the adsorption efficiency of gold.
Raw material selection of activated carbon: During the production process, heavier raw material coconut shell is needed to increase the quality and density of carbon.
Adjustment of production process: The problem of low density of CO-PROCHIM activated carbon may originate from its sintering process. The activation temperature of the charcoal can be increased or the activation activity can be changed to increase the density of the activated charcoal. The activation temperature affects the pore structure and density of the carbon and needs to be strictly regulated.
Optimisation of particle size distribution and particle morphology: Low-density chars tend to have smaller pore sizes, which may cause them to float to the surface in leach reactors. The settling properties can be enhanced by adjusting the particle size distribution of the particles, especially by increasing the proportion of particles.
For gold recovery, choosing the right activated carbon is crucial. If the quality of the carbon is poor, not only will it be ineffective, but it will also lead to gold loss, which will result in significant losses.
Huamei Activated Carbon Company is a professional manufacturer of coconut shell activated carbon with more than 50 stable cooperation customers in the field of gold refining in Egypt, Sudan, Libya, Tanzania, Burkina Faso, Ghana, Turkey, Uzbekistan, Hong Kong, Kyrgyzstan and other countries. Huamei Activated Carbon has been well received, if you need activated carbon, please feel free to contact us!
