Method for controlling iron transfer through extraction of high-iron feed liquid

Abstract

The invention relates to a method for controlling iron transfer through high-iron feed liquid extraction, and overcomes the defects in the prior art. Comprising the following steps: 1) carrying out multi-stage parallel extraction by using an extraction device, and conveying raffinate to a storage yard through a reflux pipeline for cyclic utilization; 2) arranging a washing water circulating tank and a washing water circulating pump to construct a washing-grade water phase circulating system, keeping the total volume V washing water of washing water circulation to be greater than or equal to V organic phase, and adjusting the opening degree of a washing water-grade reflux valve according to the feedback value of the online conductivity meter to control the continuous water phase in the washing mixing chamber; (3) establishing a double-circulation discharging system of the electro-barren liquor and the washing water, and keeping the iron concentration of the electro-barren liquor, the copper concentration of the washing water and the acid concentration in a certain range by adjusting the discharging flow; and 4) arranging a steady flow plate and an inclined overflow baffle in the organic phase tank to implement standing dehydration of the organic phase, and conveying the water phase to an extraction clarification tank through a centrifugal pump. The chemical extraction amount of the organic phase to iron during extraction is reduced; the washing of the washing water on the organic phase is enhanced; and the washing effect of washing water is improved.

Description

Technical Field

[0001] This invention belongs to the field of copper hydrometallurgy, specifically relating to a method for controlling iron transfer during high-iron molten metal extraction. Background Technology

[0002] In the copper hydrometallurgical extraction process, the heap leaching-extraction-electrowinning process is used to produce cathode copper. Iron in the ore forms ions that enter the extraction solution during the leaching reaction. After copper is extracted through the extraction system, the raffinate is returned to the heap for recycling. This causes iron ion impurities to continuously accumulate in the hydrometallurgical system. Iron is continuously transferred to the electrowinning solution through chemical extraction by the extractant and physical entrainment between the organic phase and the solution. Iron ions in the electrowinning solution undergo continuous redox reactions between the anode and cathode. This side reaction is the main reason for the reduced copper electrowinning current efficiency, directly resulting in reduced output, increased energy consumption, and even excessive impurities in the cathode copper product.

[0003] When using the extraction-electrowinning process to produce cathode copper, the leaching solution circulates within the production system, causing iron ion impurities to continuously accumulate and increase in concentration. The best way to remove iron ions is to discharge a portion of the leaching solution externally. However, the leaching waste contains heavy metal ions and sulfuric acid, and treating the discharged waste requires a large amount of alkali, leading to increased smelting costs.

[0004] Some mining companies reduce the iron leaching rate by lowering the heap leaching rate. This means controlling the copper leaching in the ore to a certain extent and then stopping the leaching to reduce excessive leaching of the ore, which would lead to a large amount of iron ions being dissolved. However, if the leaching time is too short or the leaching rate is too low, the copper recovery rate will decrease.

[0005] Currently, to eliminate the influence of iron ions in the electrowinning solution, smelting enterprises can only discharge a portion of the solution to reduce the iron concentration and mitigate its impact on current efficiency. Generally, when the iron concentration in the solution is controlled below 3 g / L, the impact on current efficiency is minimal. While discharging the solution effectively alleviates the impact of iron ions on electrowinning production, it also results in the loss of copper, acid, and additives. After discharge, water, additives, and sulfuric acid must be added to maintain the acidity of the solution to ensure normal production. The larger the discharge volume, the greater the loss of copper, acid, and additives, leading to increased costs and waste.

[0006] Currently, there is limited research on methods for controlling iron transfer in extraction systems. The transfer of impurity iron ions from the extraction system to the electrowinning system mainly relies on two methods: chemical extraction of the organic phase and physical entrainment between the organic phase and the feed solution. By reducing both chemical extraction and physical entrainment of iron, the amount of iron ions transferred from the extraction system to the electrowinning system can be effectively reduced. Therefore, adopting appropriate extraction process production methods and parameter control methods can effectively control the transfer of impurity iron ions to the electrowinning system. Summary of the Invention

[0007] To address the shortcomings of the existing technology, this invention provides a method for controlling iron transfer in high-iron liquid extraction.

[0008] This invention is achieved through the following technical solutions:

[0009] A method for controlling iron transfer in ferrous feed liquid extraction, comprising:

[0010] 1) The extraction device consists of multiple mixing and clarification units. These multiple mixing and clarification units are connected in parallel by multiple feed pumps to form a multi-stage parallel extraction. The raffinate is transported to the stockpile for recycling via a return pipeline. By controlling the flow ratio of each extraction stage, the chemical extraction of iron is reduced.

[0011] 2) Set up a washing water circulation tank and washing water circulation pump to construct a washing-stage water phase circulation system, and keep the total volume of washing water circulation V washing water ≥ V organic phase. According to the feedback value of the online conductivity meter, adjust the opening of the washing-stage return valve to control the water phase in the washing mixing chamber to maintain continuity.

[0012] 3) Establish a dual-circulation external discharge system for electrolytic lean solution and washing water: after the electrolytic lean solution is continuously discharged to the washing water, fresh production water and sulfuric acid are added. The washing water is continuously discharged to the raffinate tank and fresh production water and sulfuric acid are added. By adjusting the discharge flow rate, the iron concentration of the electrolytic lean solution, the copper concentration of the washing water and the acid concentration are all kept within a certain range.

[0013] 4) Set up a flow stabilizer and an inclined overflow baffle in the organic phase tank to allow the organic phase to stand and dehydrate, so that the aqueous phase is deposited at the bottom of the tank. The aqueous phase deposited at the bottom of the organic phase tank is then transported to the extraction and clarification tank by a centrifugal pump.

[0014] Furthermore, in the multi-stage parallel extraction, the ratio of the organic phase to the feed liquid in the first stage is controlled to be 1:1.5, and the ratio of the organic phase to the feed liquid in the remaining stages is 1:1.

[0015] Furthermore, the wash water circulation pump is connected to the water phase inlet of the washing stage mixing and clarification unit to realize closed-loop circulation of wash water. When the conductivity of the online conductivity meter feedback value is ≤100μS / cm, it indicates organic phase continuity. When the conductivity is ≥500μS / cm, it indicates aqueous phase continuity. When organic phase continuity is displayed, the phase continuity is maintained at aqueous phase continuity by appropriately increasing the opening of the wash water stage return valve.

[0016] Furthermore, by adjusting the discharge flow rates of the electrolytic depletion solution and the washing water, the iron concentration in the electrolytic depletion solution is kept ≤3g / L, the copper concentration in the washing water is kept at 2-4g / L, and the sulfuric acid concentration in the washing water is kept at 18-20g / L. When the iron concentration in the electrolytic depletion solution is >3g / L, the discharge flow rate of the electrolytic depletion solution is appropriately increased. When the copper concentration in the washing water is <2g / L or the sulfuric acid concentration in the washing water is <20g / L, the discharge flow rate of the washing water is appropriately reduced.

[0017] Furthermore, the flow stabilizing plate in the organic phase tank is a vertically arranged grid baffle, the inclined overflow baffle has a vertical inclination angle of 20°, the inclination direction is the liquid flow direction, and the distance between the two baffles is 1 / 3 to 1 / 2 of the tank width.

[0018] The beneficial effects of this invention are:

[0019] 1. Reduce the chemical extraction amount of iron from organic matter by multi-stage parallel extraction and flow ratio control;

[0020] 2. By controlling the continuity of the aqueous phase through online conductivity feedback, the washing water can be used to enhance the washing of the organic phase;

[0021] 3. By adjusting the flow rate of the electrolyte and wash water, the concentration of impurities can be controlled and the washing effect can be improved;

[0022] 4. By setting up flow stabilizers and inclined baffles, the effect of organic phase static dehydration is enhanced, and the water phase entrained in the organic phase is reduced.

[0023] This method is applicable not only to traditional copper hydrometallurgical processes, but also to leaching processes for low-grade ores with high iron content, and has good potential for widespread application. Attached Figure Description

[0024] Figure 1 Flowchart of a two-stage parallel extraction process;

[0025] Figure 2 Dual-circulation external discharge operation method. Detailed Implementation

[0026] This invention relates to a method for controlling iron transfer in ferrous feed liquid extraction, which includes the following aspects:

[0027] 1) The extraction device consists of multiple mixing and clarification units. These multiple mixing and clarification units are connected in parallel by multiple feed pumps to form a multi-stage parallel extraction. The raffinate is transported to the stockpile for recycling via a return pipeline. By controlling the flow ratio of each extraction stage, the chemical extraction of iron is reduced.

[0028] In the copper extraction process, copper and iron are in competition. As the copper concentration decreases, the amount of iron extracted increases. Series countercurrent multi-stage extraction can achieve a higher extraction rate, resulting in a lower copper concentration in the raffinate and more thorough copper extraction. For high-iron impurity leachates, if series countercurrent multi-stage extraction is used, it will lead to an increase in the amount of iron chemically extracted. Therefore, this method adopts a parallel multi-stage extraction production mode to effectively reduce the chemical extraction of iron.

[0029] 2) Set up a washing water circulation tank and washing water circulation pump to construct a washing-stage water phase circulation system, and keep the total volume of washing water circulation V washing water ≥ V organic phase. According to the feedback value of the online conductivity meter, adjust the opening of the washing-stage return valve to control the water phase in the washing mixing chamber to maintain continuity.

[0030] The washing of the organic phase by the wash water involves two aspects. First, through mixing and clarification of the wash water with the organic phase, the high-concentration iron-containing liquid carried over from the extraction stage is washed away, preventing its transfer to the electrodeposition system. Second, the wash water contains a certain concentration of copper and acid, which can back-extract the iron chemically extracted from the organic phase. This method sets up a wash water circulation tank to increase the wash water volume and improve the physical washing effect. Based on the feedback value of the online conductivity meter, the opening of the wash water stage reflux valve is adjusted to control the continuity of the aqueous phase in the washing mixing chamber. Compared with the continuity of the organic phase, the continuous aqueous phase enhances the physical washing and chemical back-extraction iron removal effects.

[0031] 3) Establish a dual-circulation external discharge system for electrolytic lean solution and washing water: after the electrolytic lean solution is continuously discharged to the washing water, fresh production water and sulfuric acid are added. The washing water is continuously discharged to the raffinate tank and fresh production water and sulfuric acid are added. By adjusting the discharge flow rate, the iron concentration of the electrolytic lean solution, the copper concentration of the washing water and the acid concentration are all kept within a certain range.

[0032] The electrolytic lean solution is continuously discharged to the wash water, and the wash water is discharged to the raffinate. All discharged liquids are eventually returned to the wet process system for reuse, realizing the effective utilization of discharged electrolytic lean solution and discharged wash water. At the same time, it can effectively ensure that the iron ion concentration of the electrolytic lean solution is controlled at a stable and low level. The discharged electrolytic lean solution is used to adjust the copper and acid in the wash water. The copper and acid in the wash water can back-extract the iron extracted from the organic phase into the wash water.

[0033] 4) Set up a flow stabilizer and an inclined overflow baffle in the organic phase tank to allow the organic phase to stand and dehydrate, so that the aqueous phase is deposited at the bottom of the tank. The aqueous phase deposited at the bottom of the organic phase tank is then transported to the extraction and clarification tank by a centrifugal pump.

[0034] The washed organic phase will contain a small amount of wash water. Setting up a flow stabilizer slows down the flow rate of the organic phase liquid, which is conducive to the separation and sedimentation of the water phase in the organic phase. The inclined overflow baffle can block the separated water phase on one side, while the relatively pure organic phase flows from the higher side to the other side.

[0035] Multi-stage parallel extraction, consisting of at least two stages, with the ratio of organic phase to feed liquid controlled at 1:1.5 in the first stage and 1:1 in the remaining stages.

[0036] The wash water circulation pump is connected to the water phase inlet of the washing stage mixing and clarification unit to realize closed-loop circulation of wash water. The feedback value of the online conductivity meter indicates that when the conductivity is ≤100μS / cm, the organic phase is continuous, and when the conductivity is ≥500μS / cm, the water phase is continuous. When the organic phase is continuous, the phase continuity is maintained at the water phase continuity by appropriately increasing the opening of the wash water stage return valve.

[0037] By adjusting the discharge flow rates of the electrolytic depletion solution and the washing water, the iron concentration in the electrolytic depletion solution should be ≤3g / L, the copper concentration in the washing water should be 2-4g / L, and the sulfuric acid concentration in the washing water should be 18-20g / L. When the iron concentration in the electrolytic depletion solution is >3g / L, the discharge flow rate of the electrolytic depletion solution should be appropriately increased. When the copper concentration in the washing water is <2g / L or the sulfuric acid concentration in the washing water is <20g / L, the discharge flow rate of the washing water should be appropriately reduced.

[0038] The flow stabilizer in the organic phase tank is a vertically installed grid baffle, and the inclined overflow baffle has a vertical inclination angle of 20°, with the inclination direction being the liquid flow direction. The distance between the two baffles is 1 / 3 to 1 / 2 of the tank width.

[0039] A method for controlling iron transfer in high-speed iron feed liquid extraction involves a copper extraction system with two stages of mixing and clarification extraction units. The organic phase in the organic phase storage tank is pumped into the S1 back-extraction system via an organic phase circulation pump. The loaded copper is back-extracted by the acid in the lean electrolyte, and the loaded organic phase becomes an empty organic phase. The empty organic phase then enters the extraction stages E1 and E2 sequentially to extract copper from the feed liquid. The extracted loaded organic phase enters the washing stage S2 for washing and impurity removal. The purified organic phase flows into the organic phase storage tank, and the production process is repeated. The wash water in S2 continuously circulates within the system. The raffinate from the extraction stages E1 and E2 flows into the raffinate pool and is returned to the storage yard for reuse. The lean electrolyte in S1 becomes a copper-rich solution after back-extraction and enters the electrodeposition process. After electrodeposition to produce cathode copper, it becomes a lean electrolyte.

[0040] The feed pumps are connected in parallel to supply liquid to the E1 and E2 extraction stages. The ratio of organic phase to feed liquid in the first stage E1 is 1:1.5, and the ratio in the second stage E2 is 1:1.

[0041] The washing water circulation tank and washing water circulation pump form a closed-loop circulation, controlling the total volume of washing water to be no less than the total volume of organic phase circulation. A conductivity meter is installed in the washing water S2 mixing chamber. When the conductivity is greater than 500 μS / cm, it indicates that the aqueous phase is continuous, and when the conductivity is less than 100 μS / cm, it indicates that the organic phase is continuous. The opening of the washing water return valve is adjusted according to the conductivity value to keep the conductivity greater than 500 μS / cm and maintain the S2 washing stage as an aqueous phase continuous.

[0042] like Figure 2As shown, the lean electrolyte solution is continuously discharged to the wash water at a certain flow rate to maintain the iron concentration in the lean electrolyte solution not exceeding 3 g / L, and an equal flow rate of fresh production water is added. Sulfuric acid is added appropriately according to the acidity value. The wash water is continuously discharged to the raffinate tank at a certain flow rate to maintain the wash water volume balance. The discharge volume is equal to the sum of the fresh production water replenishment volume and the lean electrolyte solution discharge volume. The wash water discharge flow rate is adjusted to maintain the copper concentration in the wash water within the range of 2–4 g / L and the sulfuric acid concentration within the range of 18–20 g / L.

[0043] During production, the drainage pump after the organic phase tank runs continuously to discharge the water phase deposited in the organic phase.

[0044] Example 1:

[0045] A copper extraction system consists of two stages of mixed clarification extraction units. The organic phase extractant concentration is 20%, and the feed solution mainly contains 6-8 g / L copper, 50-60 g / L iron, and 8-10 g / L acid. The back-extraction solution has an acid concentration of 170-190 g / L. The production process flow diagram is shown below. Figure 1 As shown, the operating flow rates are: organic phase 500 m³ / h, feed solution E1 750 m³ / h, feed solution E2 500 m³ / h, lean electrolyte solution 200 m³ / h, and wash water 500 m³ / h. The initial opening of the wash water return valve is 15%, and the valve opening is adjusted according to the conductivity value to ensure the conductivity is greater than 500 μS / cm, maintaining the S2 washing stage as a continuous aqueous phase. The lean electrolyte solution is continuously discharged to the wash water at an initial flow rate of 3 m³ / h, and replenished with an equal flow rate of fresh production water. The discharge flow rate of the lean electrolyte solution is adjusted according to the iron content analysis value to ensure the iron concentration does not exceed 3 g / L. The wash water is continuously discharged to the raffinate tank at an initial flow rate of 28 m³ / h, and replenished with 25 m³ / h of water to maintain wash water volume balance. Based on the copper and acid test values ​​of the wash water, adjust the outflow rate of the wash water to keep the copper concentration in the wash water within the range of 2-4 g / L and the sulfuric acid concentration within the range of 18-20 g / L.

[0046] After running for two hours, the iron content of the electrolyte was measured, and the organic phases from the outlets of the first-stage E1, second-stage E2, and washing stage S2 were extracted and analyzed.

[0047] Comparative Example 1:

[0048] This example is basically the same as Example 1 in terms of operation method and control parameters, except that it adopts a two-stage series countercurrent extraction process.

[0049] Comparative Example 2: This example is basically the same as Example 1 in terms of operation method and control parameters. The difference is that the wash water phase reflux valve is closed, the organic phase reflux valve opening is 15%, and the wash water clarification chamber is a continuous organic phase.

[0050] Comparative Example 3: This example is basically the same as Example 1 in terms of operation method and control parameters. The difference is that the electrolyte is directly discharged into the extraction tank, and an appropriate amount of sulfuric acid is added to the wash water to control the acid concentration of the wash water in the range of 18-20 g / L.

[0051] Table 3. Examples and comparative studies of laboratory analysis results

[0052]

[0053] Based on the analysis results in Table 3, compared with the example, Comparative Example 1 showed a higher iron content in the organic phase at the E1 extraction outlet. This was mainly because the copper concentration in the feed solution decreased during the series extraction process, which weakened the inhibition of iron extraction and increased the extraction of iron from the organic phase. Compared with the example, Comparative Example 2 showed a higher iron content in the organic phase at the washing outlet, indicating that the use of a continuous aqueous phase in the washing stage in the example was beneficial to improving the washing effect. The results of Comparative Example 3 were not significantly different from those of the example, but additional sulfuric acid needed to be added to the washing water, which increased the production cost.

[0054] The embodiments of the present invention have at least the following advantages or beneficial effects: reducing the chemical extraction amount of organic phase relative to iron during extraction through multi-stage parallel extraction and flow ratio regulation; enhancing the washing effect of washing water on organic phase by controlling the continuity of aqueous phase through online conductivity feedback; and achieving impurity concentration control and improving the washing effect of washing water by adjusting the discharge flow rate of the low-electrolyte solution and washing water.

[0055] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A method for controlling iron transfer in high-iron feed liquid extraction, characterized in that: include: 1) The extraction device consists of multiple mixing and clarification units. These multiple mixing and clarification units are connected in parallel by multiple feed pumps to form a multi-stage parallel extraction. The raffinate is transported to the stockpile for recycling via a return pipeline. By controlling the flow ratio of each extraction stage, the chemical extraction of iron is reduced. 2) Set up a washing water circulation tank and washing water circulation pump to construct a washing-stage water phase circulation system, and keep the total volume of washing water circulation V washing water ≥ V organic phase. According to the feedback value of the online conductivity meter, adjust the opening of the washing-stage return valve to control the water phase in the washing mixing chamber to maintain continuity. 3) Establish a dual-circulation external discharge system for electrolytic lean solution and washing water: after the electrolytic lean solution is continuously discharged to the washing water, fresh production water and sulfuric acid are added. The washing water is continuously discharged to the raffinate tank and fresh production water and sulfuric acid are added. By adjusting the discharge flow rate, the iron concentration of the electrolytic lean solution, the copper concentration of the washing water and the acid concentration are all kept within a certain range. 4) Set up a flow stabilizer and an inclined overflow baffle in the organic phase tank to allow the organic phase to stand and dehydrate, so that the aqueous phase is deposited at the bottom of the tank. The aqueous phase deposited at the bottom of the organic phase tank is then transported to the extraction and clarification tank by a centrifugal pump.

2. The method for controlling iron transfer in high-iron feed liquid extraction according to claim 1, characterized in that: In the multi-stage parallel extraction, the ratio of organic phase to feed liquid in the first stage is controlled to be 1:1.5, and the ratio of organic phase to feed liquid in the remaining stages is 1:

1.

3. The method for controlling iron transfer in high-iron feed liquid extraction according to claim 1, characterized in that: The wash water circulation pump is connected to the water phase inlet of the washing stage mixing and clarification unit to realize closed-loop circulation of wash water. The conductivity of the online conductivity meter feedback value is ≤100μS / cm, indicating organic phase continuity. When the conductivity is ≥500μS / cm, it indicates aqueous phase continuity. When the organic phase is continuous, the phase continuity is maintained at aqueous phase continuity by appropriately increasing the opening of the wash water stage return valve.

4. The method for controlling iron transfer in high-iron feed liquid extraction according to claim 1, characterized in that: By adjusting the discharge flow rates of the electrolytic depletion solution and the washing water, the iron concentration in the electrolytic depletion solution should be ≤3g / L, the copper concentration in the washing water should be 2-4g / L, and the sulfuric acid concentration in the washing water should be 18-20g / L. When the iron concentration in the electrolytic depletion solution is >3g / L, the discharge flow rate of the electrolytic depletion solution should be appropriately increased. When the copper concentration in the washing water is <2g / L or the sulfuric acid concentration in the washing water is <20g / L, the discharge flow rate of the washing water should be appropriately reduced.

5. The method for controlling iron transfer in high-iron feed liquid extraction according to claim 1, characterized in that: The flow stabilizer in the organic phase tank is a vertically installed grid baffle, and the inclined overflow baffle has a vertical inclination angle of 20°, with the inclination direction being the liquid flow direction. The distance between the two baffles is 1 / 3 to 1 / 2 of the tank width.

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