In the flotation process of gold beneficiation, there is a reagent with extremely high visibility but rarely known to the public - it isxanthateAs the most widely used sulfide ore collector globally, the Huangyao family plays an irreplaceable role in the field of gold beneficiation. Today, we will unveil the mystery of this' golden partner 'from chemical principles to practical applications for you.
Huangyao, scientific nameXanthan acid salt（Xanthate）， It is an organic thio compound. It is called "yellow medicine" because pure yellow medicine is in the form of light yellow powder or granules.
Principles of ChemistryThe molecular structure of Huangyao contains a "hydrophobic tail" and a "mineral loving head". In the slurry, the nucleophilic head of Huangyao selectively adsorbs onto the surface of gold minerals or gold bearing sulfide minerals, while the hydrophobic tail extends into the water. In this way, the surface of mineral particles that were originally hydrophilic becomes hydrophobic. When bubbles pass through the slurry, these mineral particles that are "covered" with hydrophobic coatings will adhere to the bubbles and float up to the surface of the slurry with the bubbles, achieving separation from waste rock-5。
According to the length of the hydrocarbon chain (carbon chain), the Huangyao family can be divided into multiple members:
| Type of yellow medicine | carbon chain length | Capture capability | selectivity | Typical application scenarios |
|---|---|---|---|---|
| Ethylxanthate | Short chain (C2) | weaker | stronger | High grade, simple ore |
| Isobutyl yellow medicine | Mid chain (C4) | moderate | moderate | Conventional gold ore flotation |
| butyl xanthate | Mid chain (C4) | stronger | moderate | The mainstream choice of gold sulfide ore |
| Pentyl yellow medicine | Long chain (C5) | the strongest | weaker | Fine grained gold and low-grade ores |
Generally speaking,The longer the hydrocarbon chain, the stronger the capture ability, but the poorer the selectivityIn actual production, it is necessary to seek a balance between "capturing more" and "capturing pure" based on the properties of the ore-5。
Early gold flotation often used a single yellow medicine as a collector. However, with the gradual depletion of easily selectable ore resources, mines are facing increasingly complex raw ore: problems such as fine particle size, complex symbiotic relationships, and high mud content are emerging one after another. A single yellow medicine is often insufficient.
In recent years, research has found thatCombination collectors can produce significant 'synergistic effects'——The effect of mixing two or more drugs far exceeds the sum of their individual use-5。
1. Butyl yellow medicine+butyl ammonium black medicine (10:1 ratio)
This is one of the most classic compound combinations. Butyl yellow medicine has strong capture ability, and butyl ammonium black medicine has good selectivity, complementing each other's advantages.
Practical CaseA certain quartz diorite type high mud low sulfur gold deposit has a raw gold grade of only 1.10g/t, a high content of fine mud in the ore, and a harsh flotation environment. By adopting this combination scheme, with a total dosage of 110g/t and a ratio of 10:1, and under the condition that the grinding fineness of -0.074mm accounts for 80%, we obtainedGold recovery rate of 85.87%, gold concentrate grade of 37.22g/tExcellent indicators-5。
2. Pentyl yellow medicine+butyl ammonium black medicine (2:1 ratio)
Pentyl xanthate has a longer carbon chain and stronger capture ability, making it particularly suitable for recovering fine gold particles.
Practical CaseA metamorphic porphyry gold deposit in Shanxi Province, with a raw gold grade of only1.10g/t(Belonging to a typical low-grade ore), by using a combination of pentyl yellow medicine and butyl ammonium black medicine, and through a closed circuit process of one coarse, two fine, and two scans, obtainedGold grade 49.70g/t, recovery rate 85.92%The gold concentrate-5。
3. Composite collector+novel inhibitor
For more complex ores, a more refined combination of reagents is required. A gold mine in Shaanxi Province used a combination of water glass and XJ-11 inhibitor at dosages of 1000g/t and 500g/t, respectively, effectively solving the interference of high content mudstone gangue on the flotation of gold bearing minerals. Laboratory closed circuit experiments obtainedGold grade 94.50g/t, recovery rate 93.16%Amazing indicators, on-site verification of flotation operation recovery rateIncrease by 2.5-5 percentage points-5。
On the basis of the Huangyao family, the industry has developed more advanced modified products——DIPX(Diisopropyl xanthate disulfide). It is essentially composed of two molecules of yellow medicine connected by disulfide bonds, belonging to the "yellow medicine dimer".
Core advantages of DIPX compared to traditional yellow medicine：
More selectiveTraditional yellow medicine has strong collection ability but limited selectivity, which can easily bring up vein stones that should not float up. DIPX has stronger recognition ability for target minerals and can effectively improve concentrate grade-1。
Better water solubilityDisperse more evenly in the slurry, reduce dead corners of chemicals, and improve utilization efficiency-1。
Higher storage stabilityTraditional yellow medicine is prone to decomposition and deterioration in humid environments, while DIPX's anti deliquescence and antioxidant properties are significantly improved, and the sealed storage period at room temperature is longer-1。
Greater adaptability to the environmentLow volatility, weak irritant odor, improving workshop working environment, in compliance with occupational health control standards-1。
At present, DIPX has been widely used in gold, copper, lead-zinc, pyrite flotation and tailings valuable metal recovery scenarios, becoming one of the mainstream choices for mid to high end mineral processing projects-1。
In flotation process, the dosage of reagents directly determines the beneficiation indicators. Insufficient dosage, insufficient surface hydrophobicity of gold minerals, and low recovery rate; Excessive usage can lead to a decrease in concentrate grade and an increase in reagent costs-5。
Method for determining the optimal dosage: ThroughFlotation condition testDraw a curve of "dosage recovery grade" and find the inflection point.
Taking a certain porphyry type gold deposit as an example, when the dosage of the combined collector (pentyl yellow medicine+butyl ammonium black medicine) gradually increases from 20+10g/t to 40+20g/t, the gold recovery rate continues to rise; But when the dosage exceeds 34+17g/t, the recovery rate tends to stabilize and the concentrate grade begins to decline. Therefore,34+17g/t has been determined as the optimal dosage for this mine-5。
Traditional yellow medicine faces two major environmental challenges in use: firstly, the problem of waste liquid and exhaust gas emissions during the production process; The second challenge is the disposal of residual chemicals in mineral tailings. With the continuous tightening of national environmental policies, the yellow medicine industry is accelerating the process of survival of the fittest-1。
Industry Development Trends：
Technological threshold raised: Legitimate manufacturers with independent synthesis and purification technology and a full set of hazardous chemical qualifications are gradually occupying the mainstream
Product upgrade: towards high efficiency, low toxicity, and high selectivity
Service system improvement: transition from simply selling products to "product+technical solution"
For mining enterprises, when choosing yellow medicine products, they should not only consider the price, but also examine the manufacturer's qualification compliance, product batch stability, and technical service capabilities-1。
Huangyao, this seemingly ordinary mineral processing agent, carries the core technical code of gold flotation process. The evolution history of this family, from ethyl xanthate to pentyl xanthate, from single use to combination and compounding, from traditional xanthate to DIPX, reflects the development trend of the entire gold beneficiation industry from "extensive" to "fine" and from "high pollution" to "green and sustainable".
Understanding Huangyao is a key to understanding the gold flotation process.
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