A gold extraction process suitable for low-grade ores

Abstract

A gold extraction process suitable for low-grade ores includes grinding, classification, concentration and adsorption processes; in the grinding process, a gold extraction agent is added to the ore pulp in the mill, and after the classification and concentration processes, in the adsorption process, the concentration of the gold extraction agent in the ore pulp is maintained within 0.8-1.0 / 10000. This gold extraction process significantly improves the adsorption rate of the adsorption column while ensuring that the gold leaching rate is not affected and less gold extraction agent and calcium hydroxide are input, which not only reduces the input amount of the reagent, but also improves the recovery rate of the adsorption column, so that the gold extraction cost is significantly reduced. The beneficial effect of this gold extraction process is that the cyanide leaching time is greatly increased and the gold leaching rate is increased; the ball mill moves violently, the temperature of the ore pulp is high, and the higher temperature is conducive to increasing the dissolution rate of gold in the cyanide solution; the ore pulp is violently stirred, and the oxygen content is high, which is conducive to increasing the leaching rate of gold; it reduces environmental pollution and allows the gold extraction solution to be recycled.

Description

Technical Field

[0001] The invention relates to the technical field of mining, and in particular to a gold extraction process suitable for low-grade ores. Background Art

[0002] In the existing gold extraction process, the ore needs to go through grinding, classification, concentration and adsorption processes in sequence. Only when it reaches the adsorption process, the gold extraction agent is added to the slurry. Gold extraction is completed during the adsorption process. In order to improve the gold leaching effect, the slurry needs to be heated. Despite this, the gold extraction rate is always difficult to improve, especially for low-grade ores. The cost of gold extraction is often higher than the product value, which loses the meaning of extraction.

[0003] In the existing gold extraction process, the adsorption process is carried out in the adsorption column. It was found in production that when the ore grade was reduced from 2.33g / t to 2.06g / t, the recovery rate of the adsorption column decreased from 43% to 32%, while the grade of the tailings of the carbon slurry process increased by 0.001g / m³, while the concentration of the gold extraction reagent remained unchanged. This means that as the ore grade decreases, the loss of the adsorption column will increase, and the grade of the tailings will increase. Obviously, this will cause a significant increase in the cost of gold extraction.

[0004] In summary, when the ore grade changes negatively, the existing gold extraction process causes the gold extraction cost to be too high and can no longer bring profits to mining companies. Summary of the invention

[0005] In order to overcome the deficiencies in the background technology, the present invention discloses a gold extraction process suitable for low-grade ores, the purpose of which is to increase the gold leaching rate and reduce the gold extraction cost.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0007] A gold extraction process suitable for low-grade ores includes grinding, classification, concentration and adsorption processes; in the grinding process, a gold extraction agent is added to the ore pulp in the mill, and after the classification and concentration processes, in the adsorption process, the concentration of the gold extraction agent in the ore pulp is maintained within 0.8-1.0 / 10000.

[0008] To further improve the technical solution, during the adsorption process, the amount of carbon in the adsorption column is reduced so that the amount of carbon in each adsorption column is 300-400kg.

[0009] To further improve the technical solution, calcium hydroxide is added to the ore pulp during the grinding process.

[0010] To further improve the technical solution, after the classification and concentration steps, in the adsorption step, the concentration of calcium hydroxide in the slurry is 0.8-1.0 / 10000.

[0011] To further improve the technical solution, in the adsorption process, the amount of flocculant added per shift is 500-550g.

[0012] To further improve the technical solution, in the concentration process, after the slurry is concentrated by the concentrator, the separated water is returned to the mill in the grinding process, and the precious liquid containing gold enters the adsorption process.

[0013] To further improve the technical solution, in the adsorption process, an adsorption column is used to circulate the adsorption of the precious gold-containing liquid.

[0014] To further improve the technical solution, in the adsorption process, the tailings are returned to the mill in the grinding process.

[0015] Due to the adoption of the above technical solution, compared with the background technology, the present invention has the following beneficial effects:

[0016] 1. Greatly increased the cyanide leaching time and improved the gold leaching rate.

[0017] 2. The ball mill moves violently, and the temperature of the slurry is high. The higher temperature is conducive to increasing the dissolution rate of gold in the cyanide solution. It is estimated that about 55% of the gold in the slurry is dissolved in the grinding process.

[0018] 3. The slurry is violently stirred and has a high oxygen content, which is beneficial to increasing the gold leaching rate.

[0019] 4. Adding calcium hydroxide to the ore pulp can remove metal ions and reduce the consumption of gold extraction agents.

[0020] 5. Reduce environmental pollution and make the gold extraction liquid recycled.

[0021] For low-grade ores, this gold extraction process improves the adsorption rate of the adsorption column while ensuring that the gold leaching rate is not affected and less gold extraction agent and calcium hydroxide are input. It not only reduces the input amount of reagents, but also improves the recovery rate of the adsorption column, significantly reducing the cost of gold extraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Shown is a flow chart of the present invention. DETAILED DESCRIPTION

[0023] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0024] Embodiment 1:

[0025] A gold extraction process suitable for low-grade ore. In this embodiment, the ore grade is 2.06g / t, which belongs to low-grade ore.

[0026] like Figure 1 As shown, the gold extraction process includes grinding, classification, concentration and adsorption processes. In the grinding process, a gold extraction agent is added to the slurry in the mill. After the slurry has gone through the classification process and the concentration process, in the adsorption process, the concentration of the gold extraction agent in the slurry is ensured to be 1.0 / 10000.

[0027] Specifically, in the grinding process, a ball mill is used to grind the ore. Due to wet grinding, the fine ore is mixed with water to form a slurry. Adding a gold extracting agent to the slurry can make the gold extracting agent mix with the slurry in advance, which has the following advantages:

[0028] 1. Greatly increased the cyanide leaching time of gold and improved the leaching rate of gold.

[0029] 2. The ball mill moves violently, and the temperature of the slurry is high. The higher temperature is conducive to increasing the dissolution rate of gold in the cyanide solution. It is estimated that about 60% of the gold in the slurry is dissolved in the grinding process.

[0030] 3. The slurry is violently stirred and has a high oxygen content, which is beneficial to increasing the gold leaching rate.

[0031] The grinding balls and linings in the ball mill are made of iron, which easily produces iron ions. Too much iron ions will reduce the leaching rate of gold and consume the gold extracting agent. For this reason, calcium hydroxide is also added to the slurry. After adding calcium hydroxide, the concentration of calcium hydroxide in the slurry is 1.4 / 10000. Calcium hydroxide can make the slurry alkaline, and hydroxide reacts with metal ions such as iron ions to remove metal ions and reduce the consumption of gold extracting agents. After the reaction, the concentration of calcium hydroxide decreases. In this way, after the classification and concentration process, the concentration of calcium hydroxide in the slurry can be guaranteed to be 0.9 / 10000 in the adsorption process.

[0032] After grinding, the pulp is classified by the spiral classifier. The pulp with large particles returns to the ball mill for further grinding, and the qualified pulp enters the concentrator for concentration. There is cyanide in the gold extraction agent. In order to reduce environmental pollution, in the concentration process, after the pulp is concentrated by the concentrator, the water removed is returned to the mill of the grinding process, and the cyanide gold-containing precious liquid enters the adsorption process. Finally, the tailings in the adsorption process are pumped back to the mill through a pump for recirculation. This design is to enable the gold extraction agent and calcium hydroxide to be recycled and prevent the gold extraction agent and calcium hydroxide from polluting the environment.

[0033] In the adsorption process, the concentration of gold extracting agent and calcium hydroxide plays a decisive role not only in the gold leaching rate, but also in the adsorption rate. In the existing gold extraction process, the concentration of gold extracting agent is generally 1.2-1.5 / 10000, the concentration of calcium hydroxide is 1.4-1.7 / 10000, and the amount of flocculant added per shift is 600-800g. Practice has proved that the existing concentration of gold extracting agent and calcium hydroxide for low-grade ore not only does not increase the gold leaching rate, but reduces the adsorption rate of the adsorption column, especially when the concentration of gold extracting agent and pH value are high, the adsorption rate of the adsorption column decreases significantly.

[0034] After repeated experiments, when the concentrations of the gold extracting agent and calcium hydroxide are reduced to a reasonable range, the adsorption rate of the adsorption column can be improved without affecting the gold leaching rate and with less input of the gold extracting agent and calcium hydroxide. In this embodiment, the concentration of the gold extracting agent is 1.0 / 10000, the concentration of calcium hydroxide is 0.9 / 1000, and the amount of flocculant added per shift is 550g.

[0035] In the adsorption process, adsorption columns are used to circulate and adsorb the precious liquid containing gold. The early recovery of the adsorption column is of great significance to purifying the process water quality, recovering the amount of gold in advance, and increasing the recovery rate. The recovery rate of the adsorption column is high, and the grade of the tail liquid can also be well controlled.

[0036] Specifically, the amount of carbon in the adsorption column is first reduced, so that the amount of carbon in each adsorption column is reduced from the original 500kg to 300kg. After the amount of carbon is reduced, the activity of the carbon layer in the adsorption column can be increased, and the recovery rate of the adsorption column can be improved. In this embodiment, the height-to-diameter ratio of the adsorption column is 3.5:1, and the cyanide gold-containing precious liquid is sent from the bottom of the column to the adsorption column at a rate of 5 to 9BV / h for cyclic adsorption. Under the action of the upflow, the carbon layer dynamically adsorbs the cyanide gold-containing precious liquid, avoids the compaction of the carbon layer in the column, and increases the uniformity and stability of the liquid inlet.

[0037] After taking the above measures, the recovery rate of the adsorption column increased from 32% to 37%, an increase of 5%, the tailings grade decreased from 0.016% to 0.013g / m³, the gold-bearing carbon grade of the adsorption column increased from 650g / t to 914g / t, the unit consumption of gold extraction agent decreased from 1.35kg / t to 1.28kg / t, and the unit consumption of calcium hydroxide decreased from 4.56kg / t to 4.2kg / t. From the above data, it can be seen that this gold extraction process not only reduces the input of reagents for low-grade ores, but also improves the recovery rate of the adsorption column, significantly reducing the cost of gold extraction.

[0038] Embodiment 2:

[0039] A gold extraction process suitable for low-grade ore. In this embodiment, the ore grade is 1.736g / t, which belongs to negative grade.

[0040] In this embodiment, in the grinding process, a gold extracting agent is added to the pulp in the mill. After the pulp is subjected to the classification process and the concentration process, in the adsorption process, the concentration of the gold extracting agent in the pulp is ensured to be 0.8 / 10000, and the concentration of calcium hydroxide is ensured to be 0.8 / 1000. In the adsorption process, the amount of flocculant added per shift is 500g.

[0041] Embodiment 3:

[0042] A gold extraction process suitable for low-grade ore. In this embodiment, the ore grade is 1.941 g / t, which is a negative grade.

[0043] In this embodiment, in the grinding process, a gold extracting agent is added to the pulp in the mill. After the pulp is subjected to the classification process and the concentration process, in the adsorption process, the concentration of the gold extracting agent in the pulp is ensured to be 0.88 / 10000 and the concentration of calcium hydroxide is ensured to be 0.94 / 1000. In the adsorption process, the amount of flocculant added per shift is 520g.

[0044] Although the embodiments of the present invention have been shown and described, it is understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the protection scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A gold extraction process suitable for low-grade ores, including grinding, classification, concentration and adsorption steps, characterized in that: In the grinding process, the gold extracting agent is added to the ore pulp in the mill. After the classification and concentration processes, in the adsorption process, the mass percentage concentration of the gold extracting agent in the ore pulp is maintained within 0.008%-0.01%. At the same time, the carbon amount of the adsorption column is reduced so that the carbon amount of each adsorption column is 300-400kg.

2. A gold extraction process suitable for low-grade ores as claimed in claim 1, characterized in that: During the grinding process, calcium hydroxide is also added to the ore slurry.

3. A gold extraction process suitable for low-grade ores as claimed in claim 2, characterized in that: After the classification and concentration process, in the adsorption process, the mass percentage concentration of calcium hydroxide in the slurry is 0.008%-0.01%.

4. A gold extraction process suitable for low-grade ores as claimed in claim 1, characterized in that: In the adsorption process, the amount of flocculant added per shift is 500-550g.

5. A gold extraction process suitable for low-grade ores as claimed in claim 1, characterized in that: In the concentration process, after the slurry is concentrated by the concentrator, the separated water is returned to the mill in the grinding process, and the precious liquid containing gold enters the adsorption process.

6. A gold extraction process suitable for low-grade ores as claimed in claim 5, characterized in that: In the adsorption process, an adsorption column is used to circulate and adsorb the precious gold-containing liquid.

7. A gold extraction process suitable for low-grade ores as claimed in claim 6, characterized in that: In the adsorption process, the tailings are returned to the mill in the grinding process.

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