Flotation separation is one of the commonly used processing methods in gold ore processing plants. However, in the gold ore flotation process, part of the raw ore has a large mud content, which affects the flotation effect, and may even affect the crushing and concentrate filtering effect. Therefore, when processing gold ore with high mud content by flotation separation, how to reduce the impact of ore mud on the flotation effect of gold ore has become a widespread concern.
When studying how to reduce the influence of slime on the flotation effect of gold ore, we must first understand the property of the ore with high mud content. This type of gold ore contains a large number of gangues of easy flotation and easy argillization (talc, serpentine, chlorite, calcite, dolomite, sericite, kaolinite, montmorillonite, feldspar, etc.). It has the characteristics of high mud content, the fine particle size of metal minerals embedded, poor flotability of metal minerals, small quality, large specific surface area, etc., and the property of the ore is complex. For gold ore flotation, too much slime will cause clogging of the crusher, gold concentrate quality decline, difficulty in filtering, slower flotation speed of fine particles, and selectivity decline, which in turn will lead to lower gold recovery, flotation index deterioration.
To solve the above problems, it is necessary to take corresponding solutions for different gold ore properties to reduce and prevent the harmful effects of slime, and to strengthen the fine particle flotation, that is, use suitable process flow or use targeted flotation reagents. The specific measures are as follows:
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Ore washing is an important way to eradicate the influence of slime on the flotation effect. After one stage of crushing, a vibrating screen is added to the processing flow. The muddy part is removed by washing. The slime after screening is processed by a spiral classifier and returns to the powder ore bin or directly gets ground. The classifying overflow can be separated by flotation alone or together with grinding products. Besides, the waste rocks on the washing screen can also be manually removed to improve the grade.
Before flotation, a hydrocyclone is used to separate a certain size of slime. If the gold content in the slime is high, the slime can be processed by flotation alone. The flotation of fine slime should spend a longer time, maintain high concentration slurry (60%-70% slurry concentration), low concentration flotation (generally below 20%), and dosing in stages at the same time, increase the amount of the collector, reduce the amount of the frothing reagent, keep large aeration and small bubbles, and weaken the rising slurry flow. For the slime of easy flotation with low gold content, a small amount of the frothing reagent can also be added before flotation to remove the mud in advance.
Adding slime dispersant (such as water glass, sodium carbonate, sodium hexametaphosphate, etc.) can prevent non-selective agglomeration of fine slime, so as to fully disperse the slime to achieve mud removal and reduce the flocculation and cover effect of slime. In this process, the stepwise dosing method can be considered to reduce the harmful effects of a large amount of adsorbents in the slime.
Physical or chemical methods are used to increase the apparent particle size of the particulate minerals to improve the flotation rate and selectivity of the minerals to be separated.
(1) Selective flocculation flotation: use the flocculant to selectively flocculate the target minerals or gangue slime of particles, and then separate it by flotation.
(2) Carrier flotation: use the general flotation particle size as a carrier to cover the fine particles on the carrier, and then float out together with the carrier.
(3) Agglomeration flotation: also known as emulsification flotation. After processed by collectors, fine-grained minerals form an oily foam with minerals under the action of neutral oil.
When the flotation method is used to process the ore with high mud content, if the crusher is blocked, the recovery rate of gold ore decreases, and the flotation index deteriorates, it can be considered whether it is caused by the high mud content of the raw ore. Flotation is a relatively complex gold ore processing method. It is recommended to conduct a processing test before determining the process flow and process parameters, fully grasp the property of the ore, and adopt the recommended process flow from the processing test report to reduce the cost of gold recovery and increase the return on investment.