Gold ore processing technology: gold ore dressing

As an important precious metal, gold is widely used in many fields such as finance, jewelry, and electronics. With the development of the global economy, the demand for gold continues to grow, while gold resources are gradually decreasing and the properties of ore are becoming more complex, which makes gold ore processing technology the focus of industry attention. Efficient and environmentally friendly gold ore processing technology can not only improve the recovery rate of gold resources and increase economic benefits, but also reduce the negative impact on the environment and promote the sustainable development of the gold mining industry. Gold ore processing technology includes several aspects, such as gold ore dressing technology, pretreatment technology, leaching technology, and tailings treatment technology. This article will mainly sort out gold ore dressing process technology.

1. Gold ore flotation technology

Flotation is one of the commonly used methods in gold ore dressing. It uses flotation agents and flotation equipment to separate useful minerals from gold ore. The principle is to use the differences in the physical and chemical properties of different mineral surfaces. By adding flotation agents, the surface of gold minerals is hydrophobic and can be attached to bubbles. With the bubbles, it floats to the surface of the slurry, thereby separating from the gangue minerals.

The effect of flotation is affected by many factors. The physical conditions of gold particles, such as particle size, shape and surface properties, play an important role in the flotation results. Coarser gold particles are more likely to attach to bubbles during flotation, but if the gold particles are too coarse, they may detach from the bubbles too quickly due to gravity; while fine gold particles may affect the recovery rate because it is difficult to effectively attach to the bubbles. The mineral composition of the ore is also crucial. Different minerals will react differently with flotation reagents, and complex mineral compositions may increase the difficulty of flotation.

Flotation chemical conditions include the type and dosage of flotation reagents and the pH value of the pulp. Common flotation reagents include collectors, frothers and regulators. Collectors can enhance the hydrophobicity of the surface of gold minerals, making them easier to attach to bubbles. For example, xanthate collectors are widely used in gold flotation. Frothers are used to generate stable bubbles to provide attachment carriers for gold minerals. Regulators are used to adjust the properties of the pulp, such as changing the pH value, to optimize the flotation effect.

Physical operating conditions such as pulp concentration, aeration volume and flotation time will also affect the flotation results. Appropriate pulp concentration can ensure that the mineral is in full contact with the reagent, while avoiding the pulp being too thick or too thin to affect the flotation efficiency. Adequate aeration can provide enough bubbles, but too much aeration may cause the bubbles to be too large, reducing the adhesion effect with the gold minerals. The flotation time needs to be reasonably controlled according to the properties of the ore and the flotation index. If the time is too short, the gold minerals may not be fully floated; if the time is too long, the production cost will increase.

2. Gold mine gravity separation technology

Gravity separation is a mineral separation method that uses the difference in mineral density for separation. It is suitable for placer gold mines and certain gold-containing ores. The basic principle is that under the action of gravity, centrifugal force, water flow power, etc., the dense gold minerals and the low-density gangue minerals are stratified and separated during the movement.

Gravity separation has unique advantages in processing placer gold mines. The gold particles in placer gold mines are usually free, and the density difference with the gangue minerals is obvious. The gravity separation method can effectively recover gold. Commonly used gravity separation equipment includes shaking table, chute, jig, etc. The shaking table uses the reciprocating motion of the bed surface and the water flow to make the minerals in the slurry stratify on the bed surface according to the density difference, thereby realizing the separation of gold minerals and gangue minerals; the chute uses the flow of slurry in the inclined trough to make the gold particles with high density settle at the bottom of the trough to achieve the purpose of enrichment; the jig uses the periodic up and down alternating water flow to make the ore particles stratify according to density in the jig chamber to achieve gold recovery.

The equipment used for gravity separation of gold is simple, low-cost and zero pollution. A large amount of chemical agents are not required in the process, reducing the risk of environmental pollution. However, the gravity separation method has certain requirements for the particle size and shape of gold minerals, and is generally suitable for the recovery of coarse-grained gold. For fine-grained gold, due to its slow sedimentation rate, it is difficult to separate from gangue minerals, and the recovery rate of the gravity separation method is relatively low.

3. Gold cyanide leaching technology

Cyanide leaching is a method of extracting gold through cyanide solution, which is widely used in rock gold mines. The principle is that gold can form a water-soluble gold-cyanide complex in a cyanide solution under the condition of oxygen, thereby realizing the dissolution and extraction of gold.

Cyanide leaching has the advantages of high leaching rate and mature technology. For most rock gold ores, cyanide leaching can obtain a high gold recovery rate. The process flow of this method is relatively simple and easy to operate and control. However, there are also some serious problems with cyanide leaching. Cyanide is highly toxic and poses great harm to the environment and human health. In the production process, if cyanide leaks or is improperly handled, it will cause serious environmental pollution accidents. Cyanide leaching has certain limitations on the adaptability of ore. For ores containing certain impurities (such as arsenic, antimony, etc.), it will affect the leaching effect of gold and requires pretreatment.

4. Thiourea leaching technology for gold mines

Thiourea leaching is suitable for difficult-to-select gold ores and has unique advantages in treating certain difficult-to-treat gold ores such as carbon-containing and arsenic-containing ores. The principle is that in an acidic medium, thiourea forms a stable complex with gold, dissolving the gold into the solution.

Compared with cyanide leaching, the thiourea leaching method has a relatively fast leaching speed and can obtain a higher gold recovery rate in a shorter time. The toxicity of thiourea is relatively low, and the pollution to the environment is small, which improves the safety of production to a certain extent. In addition, the thiourea leaching method has better adaptability to certain difficult-to-treat gold mines, and can effectively solve the problems that are difficult to handle by the cyanide leaching method.

However, the thiourea leaching method also has some shortcomings. The price of thiourea is relatively high, which increases the production cost. Thiourea is unstable in acidic media and easily decomposes. The leaching conditions need to be strictly controlled, which increases the difficulty and complexity of the operation.

5. Bioleaching and biooxidation technology of gold mines

Biological leaching and biooxidation methods are methods that use microbial oxidation pretreatment to improve the gold recovery rate, which has the advantages of environmental protection and low cost. Commonly used microorganisms include Thiobacillus ferrooxidans and Thiobacillus thiooxidans, which can oxidize substances such as sulfides in ores, exposing the gold wrapped therein, thereby increasing the leaching rate of gold.

The principle of the bio-oxidation method is that microorganisms oxidize the sulfide in the ore into sulfate during their growth and metabolism, and at the same time produce acidic substances, which reduce the pH value of the slurry and promote the dissolution of gold. When treating arsenic-containing and sulfur-containing difficult-to-treat gold ores, microorganisms can oxidize harmful elements such as arsenic and sulfur to eliminate their effects on gold leaching.

Bioleaching and bio-oxidation methods have obvious environmental advantages. They do not require the use of a large amount of chemical agents, reducing pollution to the environment. The cost of this method is relatively low, and the cost of cultivating and utilizing microorganisms is not high. However, this method also has some limitations. The bio-oxidation process is greatly affected by the growth environment of microorganisms, and has strict requirements on conditions such as temperature, pH value, and oxygen content. The speed of bio-oxidation is relatively slow and requires a long reaction time, which limits its production efficiency to a certain extent.

The above is an introduction to 5 common gold beneficiation methods. In actual beneficiation plants, how to determine the gold beneficiation process requires comprehensive consideration of the ore property beneficiation test results, production scale, equipment and reagent costs, environmental protection requirements and market demand. It is recommended to tailor a suitable gold beneficiation plan based on the beneficiation test results.

Xinhai has more than 30 years of experience in gold beneficiation and has provided customized gold beneficiation plans for many gold beneficiation plants. Currently, there are more than 29 innovative gold beneficiation technologies. If you have any needs, please contact Xinhai hotline: 15311826613!