Method for removing chloride ions from leaching solution of copper heap leaching

Abstract

The invention relates to a method for removing chloride ions from copper dump leaching feed liquid, and aims to overcome the defects of the conventional dechlorination method. Comprising the following steps: 1, dechlorination: adding cuprous oxide Cu2O into a chlorine-containing copper dump leaching material liquid, controlling the mass ratio of Cu2O to Cl <-> to be 0.8-1.0, stirring at 60-80 DEG C, reacting for 2-3 hours at 60r / min, filtering, washing filter residues, combining filtrate and washing liquid, and returning the filtrate and washing liquid to a dump leaching system; and 2, a reagent regeneration step: adding the filter residue into a 2mol / L NaOH solution according to a liquid-solid mass ratio of 5: 1, introducing a reducing atmosphere at 80-100 DEG C, carrying out a stirring reaction at 60r / min for 1.5-2 hours, carrying out solid-liquid separation to obtain Cu2O, and carrying out crushing and grinding on the Cu2O to be repeatedly used for the dechlorination step. According to the method, Cu2O reacts with Cl <-> to generate insoluble copper chloride complex precipitates, so that Cl <-> in feed liquid is removed, Cu2O can be recycled through alkaline reduction treatment, and efficient recycling of resources is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of copper hydrometallurgy, and particularly relates to a method for removing chlorine ions from copper heap leaching leaching solution. BACKGROUND

[0002] At present, heap leaching and bioleaching are commonly used low-grade copper ore processing technologies. Due to the complex source of heap leaching ores, there are various types, in addition to the target metal element copper, other impurity elements may also be transferred into the leaching solution due to the leaching behavior. There are mainly two reasons for the chlorine content in the leaching solution. One is that the chlorine-containing ores such as halite, chloroxanthite, water-soluble halogen salt and chlorocuprite will cause chlorine elements to enter the leaching solution during the leaching process. The second is that in order to improve the leaching rate of copper, some production enterprises often use sodium chloride or calcium chloride and other chlorine-containing compounds as leaching aids, thereby causing the concentration of chlorine ions in the heap leaching solution to increase.

[0003] High-concentration chlorine ion leaching solution causes a series of adverse effects on the hydrometallurgical heap leaching-extraction-electro-winning (HL-SX-EW) process. The production equipment such as centrifugal pump, storage tank, extraction mixing chamber and clarification chamber are made of stainless steel, and the chlorine-containing solution will cause corrosion of the stainless steel, causing perforation, leakage or failure of the equipment, and as the concentration of chlorine ions increases, the corrosion speed increases. For the extraction system, chlorine will accelerate the emulsification of the extractant, which may cause problems such as phase separation difficulty, decrease of copper extraction rate, increase of impurity migration and the like.

[0004] Traditional chlorine removal methods such as calcium precipitation method, ion exchange method, reverse osmosis method and membrane separation method have defects such as high energy consumption, high operation cost, low efficiency or unsuitability for high-concentration Cl- system.

[0005] Patent CN104404254A adopts the method of first neutralizing the copper-lead-zinc mixed ore oxygen pressure acid leaching solution, using zinc powder or copper powder to obtain sponge copper from the neutralized leaching solution, and then using the sponge copper to react with chlorine in the neutralized leaching solution to remove chlorine in the leaching solution. The method has a long process and high investment cost, and the chlorine removal reagent cannot be recycled.

[0006] Therefore, developing a new type of chlorine removal method which is green, efficient, low in cost and can realize recycling has become a technical problem in copper hydrometallurgy. SUMMARY

[0007] The present application aims to overcome the defects of the existing chlorine removal methods, and proposes a method of using cuprous oxide (Cu2O) to remove chlorine and supporting a regeneration mechanism. The method removes Cl- in the solution by generating insoluble copper chloride complex precipitate through the reaction of Cu2O and Cl-, and can recycle Cu2O through alkaline reduction treatment, realizing efficient recycling of resources.

[0008] The present application realizes the following technical scheme:

[0009] A method for removing chloride ions from a copper heap leaching solution, comprising the following steps:

[0010] 1) A chloride removal step:

[0011] 1.1 Copper(I) oxide Cu2O is added to the chloride-containing heap leaching solution, and the molar ratio n(Cu2O) / n(Cl-) of Cu2O to Cl- is controlled to be 0.8-1.0;

[0012] 1.2 The reaction is stirred at a constant temperature of 60-80°C, and the stirring speed is 60 r / min, and the reaction time is 2-3 hours;

[0013] 1.3 Cu2O reacts with Cl- to form an insoluble Cu-Cl complex precipitate;

[0014] 1.4 After the reaction is completed, the filtrate and the filter residue are obtained by solid-liquid separation;

[0015] 1.5 The filter residue is washed with distilled water or a low Cl- solution, and the obtained washing solution is combined with the filtrate and then returned to the heap leaching system for continuous use;

[0016] 1.6 The filter residue is collected and used for the regeneration treatment in the next step;

[0017] The chloride removal reaction formula: Cu2O + 2Cl - + 2H + → 2CuCl↓ + H2O

[0018] 2) A reagent regeneration step:

[0019] 2.1 The filter residue is added to a sodium hydroxide NaOH solution with a concentration of 2 mol / L, and the liquid-solid mass ratio is controlled to be 5:1;

[0020] 2.2 The stirring reaction is carried out at 80-100°C, and the stirring speed is maintained at 60 r / min;

[0021] 2.3 Nitrogen N2 or argon Ar protective atmosphere is introduced at the same time to provide a reducing environment to prevent further oxidation of copper;

[0022] 2.4 The reaction time is 1.5-2 hours, so that the copper complex in the original filter residue is converted into Cu2O;

[0023] 2.5 After the reaction is completed, solid-liquid separation is carried out to obtain regenerated Cu2O precipitate;

[0024] 2.6 After drying, the Cu2O is ground to a fineness of 100-150 meshes, and is used as raw material for the next round of chloride removal reaction.

[0025] The regeneration reaction formula: 2CuCl + 2NaOH → Cu2O↓ + 2NaCl + H2O

[0026] Advantages of the present application

[0027] 1. The method of the present application is simple to operate and has mild conditions, and is suitable for various types of high-Cl heap leaching solutions.

[0028] 2. The efficiency of removing chlorine is high, and the removal rate of Cl- is more than 90%, significantly reducing the interference with the extractant system.

[0029] 3. The reagent Cu2O can be effectively regenerated by an alkaline reduction system, reducing waste discharge and raw material cost.

[0030] 4. No other metal impurities are introduced, ensuring closed-loop circulation of system materials and product purity.

[0031] 5. The process is green, environmentally friendly, economical and efficient, and is suitable for large-scale industrial application. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 Flow chart of the chlorine removal process. DETAILED DESCRIPTION

[0033] As Figure 1 shown, the present application provides a high-efficiency, low-cost recycling process for removing chlorine ions in high-chlorine copper leaching solution and regenerating the chlorine removal reagent.

[0034] Example: verification of chlorine removal under laboratory conditions

[0035] 1. Take 1000 mL of high-chlorine copper heap leaching solution with a chlorine ion concentration of 0.5 mol / L;

[0036] 2. Add Cu2O solid, add n(Cu2O) / n(Cl-) = 0.9 (i.e. 65 g Cu2O);

[0037] 3. Constant temperature heating in a 70°C water bath, stirring speed 60 r / min, reaction time 2.5 hours;

[0038] 4. Stand for filtration, recover the filtrate, measure the Cl- concentration, and calculate the removal rate.

[0039] 5. Wash the filter residue for regeneration treatment.

[0040] 6. Regeneration step: add the filter residue to 500 mL of 2 mol / L NaOH solution;

[0041] 7. Pass N2 gas, heat at 80°C for 2 hours, stir at 60 r / min;

[0042] 8. After filtration and drying, regenerate Cu2O, and use XRD to detect the purity of regenerated Cu2O.

[0043] 9. Repeat the above steps, two rounds of chlorine removal and regeneration, respectively, to detect the removal rate and the purity of regenerated Cu2O.

[0044]

[0045] From the above three rounds of chlorine removal and regeneration test results, three rounds of use all maintain a high removal rate and regeneration purity, the main reason for the gradual reduction of the removal rate with the increase of the number of use is that Cu2O will be lost during use, and in actual application, it should be appropriately supplemented. The high purity of regenerated Cu2O indicates that this method can realize effective regeneration of Cu2O.

[0046] The embodiments described above are part of the embodiments of the present application, rather than all the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the claimed application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

Claims

1. A method for removing chloride ions from copper heap leaching solution, characterized in that: Includes the following steps: 1) Dechlorination step: Add cuprous oxide Cu2O to the copper heap leaching solution containing chlorine, control the molar ratio of Cu2O to Cl- to be 0.8 to 1.0, stir at 60 r / min for 2 to 3 hours at 60 to 80 °C, filter, wash the filter residue, and combine the filtrate and washing liquid and return them to the heap leaching system. 2) Reagent regeneration step: Add the filter residue to a 2 mol / L NaOH solution with a liquid-to-solid mass ratio of 5:

1. Introduce a reducing atmosphere at 80-100℃ and stir at 60 r / min for 1.5-2 hours. Separate the solid and liquid to obtain Cu2O. After crushing and grinding, Cu2O can be reused in the dechlorination step.

2. The method for removing chloride ions from copper heap leaching solution according to claim 1, characterized in that: The reducing atmosphere is either nitrogen or argon.

3. The method for removing chloride ions from copper heap leaching solution according to claim 1, characterized in that: The Cu2O obtained after regeneration needs to be dried and ground to 100-150 mesh or finer particles.

4. The method for removing chloride ions from copper heap leaching solution according to claim 1, characterized in that: In the regeneration step, the filtrate obtained after solid-liquid separation after the reaction is complete can be reused as regenerated alkali solution.

5. The method for removing chloride ions from copper heap leaching solution according to claim 1, characterized in that: Low-chlorine production water or low-chlorine leachate is used to wash the filter residue.

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