How to reduce the interference of carbonaceous materials on gold ore gravity separation?

Recently, the editor shared an article about what are the factors that affect the gravity separation effect of carbonaceous gold ore? In this article, the editor will introduce how to reduce the interference of carbonaceous materials on gold ore gravity separation? This is mainly because carbonaceous materials will interfere with the gravity separation process of carbonaceous gold ore, reducing the recovery rate and concentrate grade of gold. The interference can be reduced from pretreatment, optimization of gravity separation process, adjustment of equipment parameters and selection of suitable reagents to improve the gravity separation effect.

Pretreatment reduces the impact of carbonaceous materials

Roasting pretreatment: roasting can make carbonaceous materials oxidatively decompose at high temperature and lose their ability to interfere with gold gravity separation. Traditional roasting treats ore at a high temperature of 650-750°C, which can oxidize carbonaceous materials and expose the wrapped gold, which is conducive to subsequent gravity separation. In the treatment of a carbonaceous gold ore, after roasting pretreatment, the carbonaceous material content was greatly reduced, and the gold re-selection recovery rate increased from 40% to 70%. However, roasting has problems such as high energy consumption and easy generation of harmful gases.

Chemical oxidation pretreatment: Use strong oxidants such as potassium permanganate and hydrogen peroxide to passivate carbonaceous materials, reduce their adsorption capacity for gold, and reduce interference in the re-selection process. In laboratory studies, sodium hypochlorite solution was used to pretreat carbonaceous gold ore, which effectively inhibited the activity of carbonaceous materials and improved the gold re-selection effect. However, chemical oxidation may increase costs, and some oxidants are polluting to the environment.

Optimize the re-selection process to reduce interference

Stage grinding and stage selection: According to the intercalation characteristics of carbonaceous materials and gold in carbonaceous gold ore, a stage grinding and stage selection process is adopted. First, coarse grinding and rough selection are carried out, some tailings are discarded, and the subsequent processing volume is reduced, and then the coarse concentrate is finely ground and selected. This can avoid excessive crushing of carbonaceous materials and reduce their interference with gold re-selection. A carbonaceous gold mine applied this process, and the gold concentrate grade increased by 15%.

Gravity-flotation combined process: First use gravity to recover coarse gold, and then use flotation to recover fine gold. At the same time, flotation can effectively separate carbonaceous materials. First, use jigging gravity to recover coarse gold, and then flotate the jigging tailings. The total recovery rate of gold reaches 85%, and the interference of carbonaceous materials on gravity separation is effectively reduced.

Adjust gravity separation equipment parameters to reduce interference

Optimize shaking table parameters: The parameters such as the bed slope, stroke and number of strokes of the shaking table have a great influence on the gravity separation effect. For gold mines containing carbonaceous materials, appropriately reducing the bed slope can extend the residence time of the slurry on the bed, allowing gold particles to have more time to settle and separate, and reduce the interference of carbonaceous materials. Adjust the stroke and number of strokes to make the difference in the movement trajectory of gold particles and carbonaceous materials more obvious. When processing a carbonaceous gold mine, the bed slope was adjusted from 6° to 4°, and the gold recovery rate increased by 10%.

Improve jig parameters: The water flow frequency and amplitude of the jig determine the loosening and stratification effect of the ore particles. For carbonaceous gold ores, reducing the water flow frequency and increasing the amplitude can enhance the stratification effect of high-density gold particles and carbonaceous materials, and reduce the mixing of carbonaceous materials into the gravity separation concentrate. When treating a carbonaceous gold ore, the water flow frequency was reduced from 40 times/min to 30 times/min, and the amplitude was increased from 40mm to 50mm, and the gold concentrate grade increased by 8%.

Adding agents to inhibit the interference of carbonaceous materials

Use inhibitors: Adding inhibitors can inhibit the floatability of carbonaceous materials and reduce their interference with gold gravity separation. Common inhibitors such as kerosene and salicylic acid can form an inhibitory film on the surface of carbonaceous materials, reducing the possibility of agglomeration with gold particles. Adding an appropriate amount of kerosene before gravity separation can increase the gold gravity separation recovery rate by 12%.

Adding dispersants: Some carbonaceous materials will agglomerate, affecting the separation of gold particles. Adding dispersants can make carbonaceous materials evenly dispersed in the ore pulp, reducing their interference with gold gravity separation. In the re-selection process of a carbonaceous gold ore, sodium hexametaphosphate was added as a dispersant to improve the dispersibility of the slurry and significantly increase the gold recovery rate.