Application of Froth Flotation Process in The Rock Type Gold Mining Process

Froth flotation process is the most widely used method in the rock type gold mining process. The froth flotation process is suitable for treating the gold ore with fine grain, gold-bearing quartz vein ore with good floatability, polymetallic gold-bearing sulfide ore and graphite-bearing gold ore. In this paper, we will explore the application of froth flotation process in rock type gold mining from three aspects: the froth flotation process, flotation machine and flotation reagent system.
1. Froth flotation process used in the rock type gold mining process
The reasonable mineral processing flow is decided according to the suitable process type based on the ore and the ore property, and the original mineral processing flow should be reformed according to the ore property to make the technological process more suitable to the ore property and achieve better economic benefits. It shows that the stage grinding and stage separation can be used to improve the separation effect of gold ore with misproportion dissemination, aggregate dissemination or fine dissemination.
There are much more slime in raw ore for some rock type gold ore, which is not conducive to the froth flotation separation. Therefore,the froth flotation plant often adopts the "mud sand separation" process,that is, using the individual froth flotation process to remove the mud. The slime produced by washing ore in crushing workshop is sent to an independent slime flotation circuit after dehydration treatment, and the specific technological conditions are adopted for individual flotation, which can obtain a good separation effect.
Compared with the froth flotation process of polymetallic ore, the froth flotation process used in the gold mining process is relatively simple, the gold ore often adopts the corresponding flow according to the process characteristics, mainly includes preferential flotation process and concentrated flotation process.
Some ore often contains a certain number of easily floating gold ore, the coarse particle size can be quickly floated in the roughing to timely separate this part of the easily floating minerals, which can avoid the mineral loss in the subsequent flotation loop caused by repeated circulation, and realize the separation principle of "early recovery and fast recovery ", this process is called " preferential flotation process".
For some gold ore with low grade and less carrier mineral, only a small amount of foam is produced during the roughing operation,resulting in the slurry concentration of the cleaning operation is lower, and cannot form a stable foam layer. For this kind of gold ore, the concentrator often uses concentrated flotation process, that is, rejoining the roughing foam from different flotation stages or two even more flotation series to a single cleaning operation, which can stabilize the cleaning process.

In addition, the froth flotation process used in the rock type gold mining process can also adopt a single froth flotation process, froth flotation - cyanidation process, gravity separation – froth flotation process, amalgam – froth flotation process.
2. Flotation equipment used in the rock type gold mining process
The flotation equipment used in the rock type gold mining process mainly includes flotation machineand flotation column.
Flotation machine is the main flotation equipment used to complete the froth flotation process. There are many kinds of flotation machine, which is usually divided into three categories: mechanical mechanical agitation  type flotation machine, inflatable mechanical agitation type flotation machine and no mechanical agitation type flotation machine. Among them, mechanical agitation type flotation machine is more commonly used in the rock type gold mining process, such as SF flotation cellJJF flotation cellBF flotation cell.

The flotation column is a pneumatic flotation machine without mechanical agitation device. The main part includes a circular or rectangular column and an inflatable device. The floating column is characterized by simple structure, easy to manufacture and maintain, and low energy consumption. However, it also has some disadvantages, for example, the no mechanical agitation has poor effect on the coarse and dense ore, the inflator is easy to be blocked, the drug consumption is too large, and the ore drawing must be done when parking, causing the metal loss. Therefore, the flotation column is seldom used in the rock type gold mining process.
3. Flotation reagent system used in the rock type gold mining process
In the froth flotation process, the separating effect is often improved by adding reagents. The common flotation reagents used in the rock type gold mining process mainly include xanthate, black powder, No.2 oil, pine oil, lime, soda, sodium sulfide, copper sulfate. In the selection of flotation reagents used in the gold mining process, the principle is that the reagent has strong selectivity for the gold ore and weak collection effect on the sulfide minerals (copper, lead, zinc and iron). Adopting the non-cyanide reagent is a common choice in the treatment of polymetallic gold-bearing ores. Compared with the single collector, adopting the mixed collector can achieve the better separation result.

For example, Z-200 collector (thiamine ester) has a strong selectivity for gold and copper but a weak collecting effect on iron sulfide, which can be used for "copper-sulfur separation" flotation (i.e. separation of gold and iron), but this method has a higher cost so it is rarely used in the practice.
The mixed reagent of butylammonium black and sodium n-butylxanthate (1:2) is often used in the production. The ratio of these two reagents can effectively reduce the amount of sodium n-butylxanthate and No.2 oil, which reduces the amount of sodium n-butylxanthate by 50% and reduces the amount of No. 2 oil by 50%. Therefore, this mixed reagent greatly reduce the dosage of flotation reagent, reduce the cost of the reagent and improve the reagent removal effect before concentrate cyanidation, and also improve the flotation recovery rate.
The above three aspects refer to the application of froth flotation process used in rock type gold mining process, which only can be used as reference in the actual production. It is suggested to determine the process flow and equipment according to the mineral processing test, and recommend the mineral processing equipment provider who has an aptitude for ore beneficiation test and mineral processing plant design, thus avoiding economic waste.

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