A method for in-situ activating fluorite to enhance the leaching of combined copper oxide ore

Abstract

The present invention discloses a method for in-situ activating fluorite to enhance the leaching of combined copper oxide ore, belonging to the technical field of hydrometallurgy. Fluorite powder and water are added into a pulping tank for pulping treatment, and then pumped to the bottom of an activation reaction tank to contact with sulfuric acid flowing into the activation reaction tank from a high-level tank above the activation reaction tank for activation reaction to obtain an activated slurry. The activated slurry is pumped into a leaching tank and stirred with the combined copper oxide ore in the leaching tank for leaching. By in-situ activating fluorite, this method can effectively improve the utilization rate of fluoride ions in fluorite, increase the concentration of effective fluoride ions in the pulp, and avoid the escape of fluoride ions in the form of hydrogen fluoride, giving full play to the effect of fluoride ions in enhancing the leaching of copper in combined copper oxide ore. After in-situ activating fluorite, the copper leaching rate in combined copper ore can be increased to more than 70%, and compared with the direct addition of conventional fluorite, the copper leaching rate is increased by about 15%.

Description

Technical Field

[0001] The present invention relates to a method for leaching combined copper oxide ore, in particular to a method for strengthening the leaching of combined copper oxide ore by in-situ activation of fluorite, belonging to the technical field of hydrometallurgy. Background Technique

[0002] Copper is an important mineral resource, widely used in the fields of electronics, electricity, communication, construction, etc. At present, the resources of sulfide copper ore are decreasing day by day, and the easily beneficiated sulfide copper ore is difficult to meet the industrial demand. With the continuous growth of copper demand, the efficient utilization of copper oxide ore has become a key issue. Copper oxide ore is an important copper ore resource, which has the characteristics of high oxidation rate, high combination rate, complex mineral composition, etc. There are many types of copper-containing ores in copper oxide ore, and usually contain more than five kinds of copper minerals. Among them, malachite is the most typical and common copper oxide mineral. The surface of copper oxide mineral has large surface tension and defects, which can strongly interact with water molecules to form a hydrophilic hydration layer, hinder the adsorption of collector, and reduce the efficiency of flotation. It is difficult to achieve the efficient recovery and utilization of copper oxide ore by using a single flotation process. Therefore, the efficient recovery of copper oxide ore is a difficult problem in the industry.

[0003] At present, the treatment of complex and refractory copper ores mainly includes technical means such as flotation and hydrometallurgical leaching. The most commonly used flotation method for copper oxide ore is sulfide flotation, and the commonly used sulfiding agent is sodium sulfide. Ammonium sulfate can play a role in strengthening activation. This enhanced sulfide flotation has a high-efficiency separation effect on copper oxide ore with good properties. However, most of the copper in combined copper oxide ore is dispersed in limonite and clay ore in a combined form, resulting in its non-selectability. Moreover, its pyrometallurgical roasting cost is high and the efficiency of normal-temperature hydrometallurgical leaching is low. At present, only the method of ore blending can be used for wet treatment. The core mechanism of hydrometallurgical leaching is to use the desorption effect of leaching reagents on metal ions on the surface of carrier minerals. Therefore, it is crucial to treat combined copper oxide ore by hydrometallurgical leaching process.

[0004] Hydrometallurgical leaching mainly includes atmospheric acid leaching, pressure acid leaching, ammonia leaching process and ripening leaching, etc., which are suitable for treating refractory combined copper oxide ore. The commonly used acid solution for atmospheric acid leaching and pressure acid leaching is sulfuric acid. When using atmospheric sulfuric acid leaching to treat combined copper oxide ore, the leaching rate of copper is relatively low. When pressure acid leaching is used to treat combined copper oxide ore, it can promote the leaching of copper, but it will also dissolve more iron, which has an adverse impact on the subsequent copper extraction and electrowinning process and increases the production cost. Using ammonia leaching process to treat combined copper oxide ore has the characteristics of short process flow and low cost, but the leaching rate of copper is relatively low, less than 20%, and it cannot effectively recover copper resources. The main problem of using ripening leaching to treat combined copper oxide ore is that the iron leaching rate is too high, which has an adverse impact on the subsequent copper extraction and electrowinning process.

[0005] During the leaching process of combined copper oxide ore, it is necessary to ensure a high copper leaching rate while preventing excessive iron dissolution. This is the biggest problem faced by existing technologies. Currently, there are reports on using fluoride ions to promote the leaching of combined copper oxide ore. However, for conventional water-soluble fluorides, they are prone to form hydrogen fluoride and escape, causing equipment corrosion and low fluoride ion utilization rate, significantly increasing the leaching cost. In existing industries, there are reports on using fluorite powder to enhance the leaching of copper in combined copper oxide ore. For example, the literature ("Study on Process Mineralogy of the Combined Copper Oxide Ore in Tibet and Acid Leaching Behavior with Calcium Fluoride", Zujiang Pan, et al., Minerals 2024, 14, 352) discloses that fluoride ions can erode combined copper oxide ore and promote the diffusion of hydrogen ions inside limonite, thereby enhancing the leaching of combined copper ore in limonite. Specifically, when the grinding fineness is -0.074 mm (85%), the liquid-solid ratio is 4:1, the sulfuric acid concentration is 50 g / L, the temperature is 30 °C, the CaF2 dosage is 1% of the ore mass, and the leaching time is 4 h, the copper leaching efficiency is increased to 60.57%, which is 7.34% higher than conventional atmospheric leaching. However, directly adding fluorite powder to the pulp will result in low fluoride ion concentration and the phenomenon that most fluoride ions do not enter the leaching system, leading to serious loss of fluoride ions, unsatisfactory effect of promoting the leaching of combined copper oxide, and increased production cost and waste of resources. Summary of the Invention

[0006] Aiming at the technical defects in the prior art that when using calcium fluoride to enhance the leaching of combined copper oxide ore, the utilization rate of fluoride ions in fluorite powder is low, resulting in low leaching rate and high cost of combined copper ore, the purpose of the present invention is to provide a method for in-situ activating fluorite to enhance the leaching of combined copper oxide ore. By in-situ activating fluorite, this method can effectively improve the utilization rate of fluoride ions in fluorite, increase the concentration of effective fluoride ions in the pulp, and avoid the escape of fluoride ions in the form of hydrogen fluoride, giving full play to the effect of fluoride ions in enhancing the leaching of combined copper oxide ore. After in-situ activating fluorite, the copper leaching rate in combined copper ore can be increased to more than 70%, and compared with directly adding fluorite, the copper leaching rate is increased by about 15%.

[0007] In order to achieve the above technical objectives, the present invention provides a method for in-situ activation of fluorite to enhance the leaching of combined copper oxide ore. In this method, fluorite powder and water are added into a pulping tank for pulping treatment to obtain a fluorite slurry; the fluorite slurry is pumped to the bottom of an activation reaction tank and contacts sulfuric acid flowing into the activation reaction tank from a high-level tank above the activation reaction tank for activation reaction to obtain an activated slurry; the activated slurry is pumped into a leaching tank and stirred with the combined copper oxide ore in the leaching tank for leaching.

[0008] The key to the technical solution of the present invention lies in: performing activation pretreatment on the fluorite powder can greatly increase the effective fluoride ion concentration in the activated slurry, which is beneficial to making full use of the promoting effect of fluoride ions on the leaching of copper in the combined copper oxide ore during the subsequent leaching process. If the fluorite powder is not pretreated by activation and is directly added to the leaching system, at the initial stage of leaching, sulfuric acid will react with minerals preferentially, thus affecting the effective release of fluoride ions in the fluorite. And in the later stage of leaching, with the continuous consumption of sulfuric acid during the leaching process, it becomes more difficult for fluoride ions in the fluorite to be released, resulting in the insufficient utilization of fluoride ions in the fluorite powder during the entire leaching process, and the low effective fluoride ion concentration in the leaching system, which affects the leaching efficiency of copper in the combined copper oxide ore.

[0009] As a preferred solution, the particle size of the fluorite powder is controlled such that the mass proportion of particles below 200 mesh is 50% - 80%. Theoretically, the smaller the particle size of the fluorite powder, the higher its reaction activity and the easier it is to be activated by sulfuric acid. However, over-grinding of fluorite will significantly increase the grinding energy consumption, which is disadvantageous.

[0010] As a preferred solution, the mass concentration of the fluorite slurry is controlled at 40% - 70%. The mass concentration of the fluorite slurry is further preferably controlled at 50% - 65%. The concentration of the fluorite slurry affects its activation efficiency and can ensure the concentration of effective fluoride ions in the leaching system during the subsequent leaching process. Therefore, controlling the concentration of the fluorite slurry within a suitable range is beneficial to the subsequent leaching of the combined copper oxide ore.

[0011] As a preferred solution, the top of the activation reaction tank is sealed, and the volume filling ratio of the fluorite slurry in the activation reaction tank is 70 - 90%. During the activation process of the fluorite powder, some fluoride ions in the slurry will escape in the form of hydrogen fluoride. Sealing the top of the activation reaction tank can prevent the escape of hydrogen fluoride. At the same time, increasing the volume filling ratio of the fluorite slurry in the activation reaction tank can increase the saturated vapor pressure of the hydrogen fluoride gas and strengthen the reverse dissolution of the hydrogen fluoride gas into the activated slurry.

[0012] As a preferred solution, the mass concentration of the sulfuric acid is 50% - 93%. The concentration of the sulfuric acid is further preferably 70% - 93%.

[0013] As a preferred embodiment, the molar ratio of the sulfuric acid to the fluorite powder is 1.2:1 to 1.8:1. If the proportion of the sulfuric acid is too high, the concentration of hydrogen ions in the activation slurry will be too high, thus increasing the probability of fluoride ions volatilizing in the form of hydrogen fluoride. If the proportion of the sulfuric acid is too low, it will be difficult to fully activate the fluorite powder.

[0014] As a preferred embodiment, the time of the activation reaction is 30 min to 60 min. If the activation reaction time is too short, it will be difficult to fully activate the fluorite powder. If the activation reaction time is further prolonged, the activation effect on the fluorite will not be further enhanced, but instead the production efficiency will be reduced.

[0015] As a preferred embodiment, the condition parameters of the stirring leaching are controlled as follows: the pH value of the pulp is 1.0 to 1.5, the mass concentration of the pulp is 18% to 30%, the fluoride ion concentration in the slurry is maintained at 500 to 1000 mg / L, the stirring rate is 20 to 40 r / min, and the leaching time is 12 to 24 hours.

[0016] The activation reaction tank of the present invention is a sealed stirring tank lined with anti-corrosion material to prevent the leakage of hydrofluoric acid, and is provided with a high-pressure warning device and an explosion-proof valve.

[0017] The stirring leaching tank of the present invention is a sealed stirring tank lined with anti-corrosion material, and the tops of all leaching tanks are connected to an exhaust gas treatment system.

[0018] Compared with the prior art, the beneficial technical effects brought by the present invention are as follows:

[0019] By in-situ activating the fluorite powder and then using it for the leaching of combined copper oxide ore, the present invention can greatly increase the concentration of effective fluoride ions in the leaching system, so as to effectively strengthen the dissolution and leaching of copper in the combined copper oxide ore. The leaching efficiency of copper is significantly improved by about 15% compared with the direct addition of conventional fluorite to promote leaching.

[0020] The leaching of the combined copper oxide ore by the present invention does not require conditions such as high temperature and high pressure, and can be efficiently leached, thus realizing the efficient recovery and utilization of difficult-to-utilize copper resources.

[0021] The process of activating the fluorite powder by the present invention is simple, the conditions are mild, the concentration of sulfuric acid used is relatively low, and the reaction time is short.

[0022] During the in-situ activation process of the fluorite powder and the leaching process of the combined copper oxide ore by the present invention, the leakage of hydrofluoric acid gas and the corrosion of equipment can be effectively avoided.

[0023] The present invention realizes the efficient and economic recovery of copper resources in the combined copper oxide ore, and at the same time provides theoretical guidance for the metal extraction of other complex refractory ores. Description of the Drawings

[0024] Figure 1 This is the process flow chart of the present invention.

[0025] Figure 2 This is the XRD diagram before and after in-situ activation of fluorite powder.

[0026] Figure 3 This shows the influence of different addition methods of fluorite powder on the leaching effect of a certain copper mine in Yulong, Tibet in Example 1.

[0027] Figure 4 This shows the influence of different addition methods of fluorite powder on the leaching effect of a certain copper mine in the Democratic Republic of the Congo in Africa in Example 2.

[0028] Figure 5 This shows the influence of different addition methods of fluorite powder on the leaching effect of a certain copper mine in Yunnan in Example 3. Specific implementation manners

[0029] The following specific examples are intended to further illustrate the content of the present invention, rather than limiting the protection scope of the claims of the present invention.

[0030] In the following examples, the process flow of in-situ activation of fluorite to strengthen the leaching of combined copper oxide ore is as Figure 1 shown. Fluorite powder and water are simultaneously added into the pulping tank for stirring and pulping to obtain fluorite slurry. The fluorite slurry is pumped into the bottom of the activation reaction tank by a slurry pump. The activation reaction tank is a sealed tank, and there is a high-level tank above the activation reaction tank for loading sulfuric acid. The sulfuric acid can flow into the activation reaction tank by gravity and contact with the fluorite powder for activation reaction to obtain activated slurry. The activated slurry is pumped into the leaching tank by a slurry pump and stirred and leached with the combined copper oxide ore added into the leaching tank. The top of the leaching tank is closed, and there is an exhaust pipe for discharging reaction gases. The leaching tank adopts two-stage series-connected leaching tanks, and the leaching tanks are connected by an overflow method.

[0031] Example 1

[0032] This example mainly compares the differences in the leaching effects of combined copper oxide ore under three different conditions: without adding fluorite powder, directly adding fluorite powder, and in-situ activating fluorite powder.

[0033] According to process mineralogy analysis, the copper grade of copper-bearing limonite in Yulong, Tibet is 1.29%, the iron grade is 44.17%, the main mineral is limonite, accounting for about 82%, and it has a relatively high oxidation rate. The main component of combined copper oxide is copper-bearing limonite, and its copper content accounts for more than 75%.

[0034] First, the copper-bearing limonite is crushed and ground, and then screened to particles of -0.074 mm, with 80% of the material passing through this screening. Next, leaching experiments are designed. Take 200 g of the copper-bearing limonite sample, keep the liquid-solid ratio at 3 mL:1 g, set the mechanical stirring speed at 300 r / min, the sulfuric acid concentration at 300 kg / t, and the leaching time at 4 hours.

[0035] Three groups of control conditions are set in the experiment, which are: no addition of fluorite powder, addition of 5 kg / t of fluorite powder, and grinding the fineness of 5 kg / t of fluorite powder to less than 100 mesh with 70% of it. Then slurry is made (the slurry concentration is 70%). The fluorite slurry enters the activation reaction tank with a volume filling rate of 80%, and is mixed with sulfuric acid with a concentration of 70%. The molar ratio is 1.4:1, and the reaction time is 1 hour (the measured fluoride ion concentration is 744.53 mg / L). Then the whole system is added to the leaching system.

[0036] Each group of experiments is repeated three times, and the concentrations of copper and iron in the leaching solution are measured by an inductively coupled plasma optical emission spectrometer (ICP-OES). The experimental data are shown in Table 1.

[0037]

[0038] Example 2

[0039] This example mainly compares the differences in the leaching effects of combined copper oxide ore under three different conditions: no addition of fluorite powder, direct addition of fluorite powder, and in-situ activation of fluorite powder.

[0040] According to process mineralogy analysis: In a certain clay-bound copper oxide ore in the Democratic Republic of the Congo in Africa, copper mainly exists in the oxidized state and is closely symbiotic with kaolin. The associated copper minerals account for up to 56%. The ore as a whole shows strong oxidizing properties and difficult leaching characteristics.

[0041] Before the experiment, the ore is pretreated, including crushing, grinding and screening operations, so that 80% of the material particle size is controlled at -0.074 mm to improve the reaction contact efficiency between the mineral and the leaching agent. The leaching experiment is carried out with 200 g of representative samples under the conditions of a liquid-solid ratio of 3 mL:1 g, a stirring speed of 300 r / min, a sulfuric acid addition amount of 300 kg / t, and a reaction time of 4 hours.

[0042] To investigate the effect of fluorite powder in the leaching system, three treatment methods were set for comparison: one was without adding fluorite powder as a blank control; another was directly adding 6 kg / t of fluorite powder to the leaching system; the third treatment method was to grind 6 kg / t of fluorite powder to a fineness of less than 100 mesh, accounting for 60%, and then pulp it (the slurry concentration was 70%). The fluorite slurry entered the activation reaction tank with a volume filling rate of 90%, and was mixed with sulfuric acid with a concentration of 90%. The molar ratio was 1.3:1, and the reaction time was 1 hour (the measured fluoride ion concentration was 862.43 mg / L). Then, the whole system was added to the leaching system.

[0043] All experiments were repeated three times, and the copper content in the leaching solution was determined by inductively coupled plasma optical emission spectrometer (ICP-OES) to evaluate the effect of each scheme on the copper leaching rate. The experimental results are shown in Table 2.

[0044]

[0045] Example 3

[0046] This example mainly compared the differences in the leaching effects of combined copper oxide ore under three different conditions: without adding fluorite powder, directly adding fluorite powder, and in-situ activating fluorite powder.

[0047] According to process mineralogy analysis, in a certain complex combined copper oxide ore in Yunnan, the symbiotic rate of copper with kaolin is 36.2%, the symbiotic rate with limonite is 31.7%, the rest of the copper minerals are in a free state or a weakly combined state (accounting for about 21.6%), and there is also a small amount symbiotic with other gangue minerals (such as quartz, sericite, etc.) (about 10.5%). Among them, kaolin mostly has a flaky structure, which is easy to form inclusions and hinder the contact and reaction of the leaching solution with copper minerals; while limonite, due to its strong adsorption and high specific surface area, is easy to adsorb copper ions and form a secondary encapsulation effect. This ore is a typical copper oxide ore with an oxidation rate as high as 82.4%.

[0048] Before the experiment, the ore was pretreated, including crushing, grinding and screening operations to control the particle size of 80% of the materials at -0.074 mm. The leaching experiment was carried out with 200 g of representative samples under the conditions of a liquid-solid ratio of 3 mL:1 g, a stirring speed of 300 r / min, a sulfuric acid addition amount of 300 kg / t and a reaction time of 4 hours.

[0049] Three sets of control conditions were set in the experiment, which were: no addition of fluorite powder, direct addition of 6 kg / t of fluorite powder, and grinding 70% of 6 kg / t of fluorite powder to a fineness below 100 mesh, followed by pulping (pulp concentration was 80%). The fluorite slurry entered the activation reaction tank with a volume filling rate of 75%, and then was mixed with sulfuric acid with a concentration of 90%. The molar ratio was 1.5:1, and the reaction time was 1 hour (the measured fluoride ion concentration was 932.32 mg / L). Then the whole system was added to the leaching system.

[0050] Each group of experiments was repeated three times, and the copper concentration in the leaching solution was measured by inductively coupled plasma optical emission spectrometer (ICP-OES). The experimental data are shown in Table 3.

[0051]

[0052] From the experimental data of Examples 1 to 3 and Tables 1 to 3 above, it can be seen that: during the sulfuric acid leaching of various combined copper oxide ores, the addition of fluorite powder can promote the leaching of combined copper oxide ores to a certain extent, and compared with not performing in-situ activation treatment on the added fluorite powder, the leaching effect of combined copper oxide ores is significantly improved by performing in-situ activation treatment on the added fluorite powder.

Claims

1. A method for in-situ activating fluorite to strengthen the leaching of combined copper oxide ore, characterized in that: Add fluorite powder and water into the pulping tank for pulping treatment to obtain fluorite slurry; pump the fluorite slurry into the bottom of the activation reaction tank to contact with sulfuric acid flowing into the activation reaction tank from the high-level tank above the activation reaction tank for activation reaction to obtain activated slurry; pump the activated slurry into the leaching tank and carry out stirring leaching with the combined copper oxide ore in the leaching tank. The top of the activation reaction tank is sealed, and the volume filling ratio of the fluorite slurry in the activation reaction tank is 70% - 90%; the mass concentration of the sulfuric acid is 50% - 93%; the molar ratio of the sulfuric acid to the fluorite powder is 1.2:1 - 1.8:

1.

2. The method for in-situ activating fluorite to enhance the leaching of combined copper oxide ore according to claim 1, characterized in that: The particle size of the fluorite powder is controlled below 200 mesh, and the mass ratio is 50% - 80%.

3. The method for in-situ activating fluorite to enhance the leaching of combined copper oxide ore according to claim 1, wherein: The mass concentration of the fluorite slurry is controlled at 40% - 70%.

4. A method for in-situ activating fluorite to enhance the leaching of combined copper oxide ore according to claim 1, characterized in that: The time of the activation reaction is 30 min - 60 min.

5. A method for in-situ activating fluorite to enhance the leaching of combined copper oxide ore according to claim 1, characterized in that: The condition parameters of the stirring leaching are controlled as follows: the pH value of the pulp is 1.0 - 1.5, the mass concentration of the pulp is 18% - 30%, the concentration of fluoride ions in the slurry is maintained at 500 - 1000 mg / L, the stirring rate is 20 - 40 r / min, and the leaching time is 12 - 24 hours.

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