In one ton of gold ore, the gold content is often only a few grams, and the rest is all waste rock. To extract these few grams of gold from tons of stones, physical methods alone are far from enough, and the power of chemical agents must be utilized.
In gold beneficiation, the reagents have clear division of labor and each performs its own duties. Today, let's get to know several key members of this' potion family '.
Gold ore is ground into powder and poured into water. Most mineral particles have a hydrophilic surface - they prefer to stay in water and do not want to float.
The function of a collector is to change this state. It selectively adsorbs onto the surface of gold containing minerals and wraps a hydrophobic film around the mineral particles. It's like putting a "swimsuit" on gold minerals, making them willing to lean against bubbles and float to the surface of the water。
The most commonly used collector in gold flotation isxanthate(The scientific name is xanthate, named after its pale yellow appearance). According to the length of the carbon chain, Huangyao is divided into different models: short chain is relatively mild, long chain has stronger capture ability, and is suitable for dealing with difficult to select ores。Black medicineIt is another type of commonly used collector, sometimes used in combination with yellow medicine, and the effect is better than using either alone。
Mineral particles wearing swimsuits need transportation tools - bubbles - to float to the surface.
The function of a foaming agent is to reduce the surface tension of water, making it easier for the air filled in the water to form small bubbles, and making these bubbles less likely to burst. The commonly used foaming agents arePine alcohol oil(also known as No. 2 oil), it is very common in flotation workshops。
Collectors and foaming agents also have a "cooperative" relationship: they will jointly adsorb on the surface of mineral particles, helping minerals to adhere more smoothly to bubbles and complete flotation。
If the collector and frother are the "actors" on stage, then the adjuster is the "overall dispatcher" behind the scenes - it does not directly participate in capturing gold, but is responsible for creating the best conditions for the entire flotation process。
There are many family members of adjusters, each responsible for different tasks:
PH adjusterAdjust the acidity and alkalinity of the slurry. Lime, sodium carbonate, and sulfuric acid are commonly used, with lime and sulfuric acid being the most commonly used for gold selection。
activatorIf the target mineral is "suppressed" and not easily floated, an activator can help it "wake up" and enhance its ability to interact with the collector。
inhibitorSome minerals (such as impurities that do not want to come up with them) have too good floatability, and inhibitors can "press" them to prevent them from floating up with gold。
Coagulants and dispersantsFine mineral particles are prone to agglomerate or float everywhere. coagulants help them "clump" and accelerate sedimentation, while dispersants do the opposite, helping them disperse。
In addition to flotation reagents, there is another major category in gold beneficiation - leaching reagents, which are used to "dissolve" gold from ores. The traditional leaching agent is sodium cyanide, which has good gold leaching effect and low cost. However, it is a highly toxic chemical, and its transportation, storage, and use are strictly controlled. Once leaked, the consequences can be serious。
In recent years, environmentally friendly mineral processing agents are gradually replacing traditional sodium cyanide. The technical idea of this type of product is to replace inorganic substances containing cyanide groups with organic compounds containing cyanide groups, and to "lock" the cyanide groups through molecular structure design. Under normal conditions, it is not easy to release free toxic components, but it can effectively dissolve gold during immersion。
The core advantage of environmentally friendly mineral processing agents is that their toxicity is significantly reduced, making them suitable for general cargo transportation; It can directly replace sodium cyanide without the need to modify existing equipment and processes; The treatment of tailings after leaching is relatively simple。
A drug often has more than one effect. For example, black medicine has both capturing ability and foaming effect; Water glass can both inhibit gangue minerals and have a dispersing effect; Lime is both a pH adjuster and an inhibitor of pyrite。
There is also a mutual constraint relationship between drugs. For example, sulfuric acid can decompose yellow medicine; Water glass can change the acidity or alkalinity of the slurry. So, the selection of the type of reagent, the amount used, the order of addition, and the location of addition all need to be adjusted according to the specific properties of the ore. This is what mineral processing engineers often refer to as the "reagent system"。
The composition of ore varies greatly from mine to mine, and the effective formula for A mine may not be effective in B mine. Therefore, determining the optimal chemical solution often requires exploration through specialized beneficiation experiments。
The core task of mineral processing reagents is to efficiently separate rare gold from a large amount of waste rock. The collector is responsible for "putting swimsuits" on the gold, the foaming agent is responsible for creating "transport bubbles", and the adjusting agent is responsible for regulating the entire "working environment" - each performing their own duties and working together to complete the task of "turning stones into gold".
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