In the field of gold beneficiation, flotation is one of the most widely used technologies. Its core principle is not complicated: by utilizing the differences in physical and chemical properties of mineral surfaces and adding chemical agents, gold containing mineral particles are attached to bubbles and float to the surface of the slurry, thereby achieving separation from gangue minerals-6。

However, behind this seemingly simple process lies a sophisticated 'chemical command system'——Collector, foaming agent, adjusting agentThe three major types of potions each perform their own duties and work together to accomplish the task of "turning stones into gold". Today, we will delve into the mystery of this' golden triangle '.

1、 Collector: Put a hydrophobic coat on gold

Collectors are the most essential type of flotation reagentsThe vast majority of minerals (including gold minerals) in nature have naturally hydrophilic surfaces. If left untreated, they will sink to the bottom of the water and cannot float up with bubbles-9The function of a collector is to selectively adsorb onto the surface of the target mineral, using a hydrophobic "tail" facing outward to give the mineral particles a hydrophobic coating.

Huangyao family: the "main force" of gold flotation

The most commonly used collector for gold associated with sulfide minerals such as copper, lead, zinc, and iron in flotation is organic sulfur compounds, among whichxanthate(Xanthan acid salt) is the most typical-9。

According to the length of the hydrocarbon chain, members of the Huangyao family have their own division of labor:

Generally speaking,The longer the hydrocarbon chain, the stronger the capture ability, but the poorer the selectivityTherefore, when choosing a collector, it is necessary to find a balance between "capturing more" and "capturing pure".

Combination therapy: synergistic effect of "1+1>2"

In modern flotation processes, a single collector is no longer sufficient to meet the processing needs of complex ores. Research finds thatThe combination of different collectors often produces significant synergistic effects-2-6。

Typical case:

• Butyl yellow medicine+butyl ammonium black medicineThis is the most classic combination of compounds. The 1:1 combination of the two achieved good indicators of gold grade 38.4g/t and recovery rate 84.73% in the closed-circuit flotation of a difficult to select gold mine-5。

• Isoamyl yellow medicine+Butylamine black medicineUnder low alkalinity conditions (pH=8), this combination achieved a gold recovery rate of 93.47% for a certain gravity tailings-2。

• Alternative plan for pentyl xanthateAfter replacing butyl xanthate with pentyl xanthate in a gold mine in Gansu, the gold recovery rate increased from 89.25% to 90.27%, and the grade increased from 28.97g/t to 30.19g/t-8。

2、 Foaming agent: the magician who manufactures "transportation vehicles"

If the collector is responsible for making minerals' want to float ', thenFoaming agents are responsible for making minerals' able to float ' 的关键。

The role of foaming agent is to reduce the surface tension of the aqueous solution, so that the air filled in the water is easy to disperse into small bubbles and produce stable foam-9Without a foaming agent, the bubbles will quickly burst, and mineral particles cannot "ride" on the bubbles to rise to the surface of the slurry.

Common foaming agents include：

• Pine alcohol oil (No.2 oil)The most widely used foaming agent, with low price and stable effect

• Ether alcoholsMore delicate foaming performance and better selectivity

• Phenolic acid, mixed fatty alcoholswait

There are foaming agents and collectors presentcombined effect——Both adsorb together on the surface of mineral particles, promoting mineral flotation-9Therefore, the type and amount of foaming agent need to be adjusted in conjunction with the collector to achieve optimal results.

3、 Adjustment agent: the "chief dispatcher" of flotation environment

Adjusters are the general term for all flotation agents, except for collectors and frothers, used to adjust the interaction between collectors and minerals, regulate the pH and ion composition of the slurry, and promote or inhibit the floatability of minerals-1-6Adjusters can be divided into five categories-1-9：

1. pH adjuster: Control the acidity and alkalinity of the "chemical battlefield"

The pH value directly affects the surface charge of minerals, the dissociation state of reagents, and the direction of chemical reactions.Lime and sodium carbonate are the most commonly used pH adjusters-1。

• limeLow cost and effective inhibition of pyrite, it is the most commonly used adjusting agent for sulfide ore flotation. But lime can form a hydrophilic film to encapsulate minerals, sometimes even inhibiting the flotation of gold-1。

• sodium carbonateWeak alkalinity, suitable for pH sensitive gold mines. The experiment of a low-grade gold mine in Guangxi showed that when sodium carbonate was used as an adjusting agent, the concentrate grade reached 24.70g/t and the recovery rate was 85.08%, which was better than that of lime-7。

• sodium hydroxideProviding precise pH control, a high recovery rate of 93.47% was achieved in the flotation of a certain gravity tailings by adjusting the pH to 8 with NaOH-2。

2. Activating agent: awakens dormant minerals

Activating agents can enhance the ability of minerals to interact with collectors, awakening previously difficult to float minerals-1。

• copper sulfateThe most widely used activator. It can undergo displacement reactions with the surfaces of sphalerite and pyrite, generating copper sulfide films that are easily captured by yellow medicine-5-8。

• sodium sulfideUsed to activate lead copper oxide ore containing gold, generate a sulfide film on the surface of the oxide ore, and then use yellow medicine flotation-1。

3. Inhibitors: Goalkeepers who distinguish between "friend and foe"

The function of inhibitors is to enhance the hydrophilicity of gangue minerals and prevent their interaction with collectors-1。

• water glassThe most commonly used vein stone inhibitor has a good inhibitory effect on quartz and silicate minerals-1-5。

• limeIt is both a pH adjuster and an inhibitor of pyrite. Pyrite inhibited by lime can be activated by sodium carbonate and copper sulfate before flotation-1。

• Sodium cyanideA potent inhibitor that can inhibit various sulfide minerals such as pyrite and sphalerite. But due to toxicity issues, it is gradually being replaced by low toxicity agents such as sulfites-1。

4. coagulants and dispersants: experts in fine mud management

• flocculant(such as polyacrylamide) causes fine particles to aggregate into larger particles, accelerating settling speed

• dispersant(such as water glass, phosphate) prevents the aggregation of fine mineral particles and maintains the dispersed state of monomers-1-9

For gold mines with high mud content, the rational use of coagulants and dispersants can significantly improve flotation efficiency.

4、 Practical interpretation of the "Golden Triangle": a complete pharmaceutical system

Taking a difficult to select gold mine in Shaanxi as an example, the complete composition of its flotation reagent system is as follows-5：

This pharmaceutical system has undergone a closed-loop flotation process of "two roughing, two sweeping, and three refining" to obtainGold grade 38.4g/t, recovery rate 84.73% 的良好指标-5。

5、 The wisdom of choosing a pharmaceutical system

For gold mining enterprises, how to determine the appropriate chemical system for their own ores?

1. 'Tailoring to the needs of the mine' is an iron law

There is no universally applicable 'miracle drug'. It must be done through the systemFlotation condition testDraw the curve of "dosage recovery grade" and find the optimal turning point-2-3-8。

2. Pay attention to the "side effects" of medication

Each medication has multiple effects. For example, lime is both a pH adjuster and a pyrite inhibitor; Sodium sulfide is an activator when used in small amounts, but becomes an inhibitor when used in large amounts-1Understanding these 'multiple identities' is the foundation of fine regulation.

Combination therapy is the trend

A single agent is often insufficient, while a reasonable combination of different agents can produce synergistic effects-6Whether it is the compounding of collectors or the combination of adjusters, they are effective means to improve mineral processing indicators.

4. Continuous optimization is the norm

The properties of the ore will change with the depth of mining and the variation of the ore section. The pharmaceutical system also needs to be dynamically adjusted, rather than remaining unchanged-6。

Conclusion

The "golden triangle" composed of collectors, frothers, and adjusters is the core soul of flotation technology. The capturing agent is responsible for "identifying and capturing" target minerals, the foaming agent is responsible for "manufacturing transportation vehicles," and the adjusting agent is responsible for "optimizing the battlefield environment. The three parties each perform their respective duties and work together to complete the precise task of enriching gold from ore.

Understanding the operational logic of this "golden triangle" not only helps us understand the technical connotation of flotation technology, but also provides ideas for reducing costs and increasing efficiency for mining enterprises. After all, on the journey of "turning stones into gold", there is no panacea, onlyThe most suitable formula for one's own ore。