Method for reducing content of sulfuric acid in low-copper raffinate and recovering copper

Abstract

The invention relates to the technical field of hydrometallurgy, in particular to a method for reducing the content of sulfuric acid in low-copper raffinate and recovering copper, which comprises the following steps: S1, pre-neutralizing; step S2, dense separation; s3, extracting to remove copper; and S4, neutralizing and removing iron. According to the method, high-acid-consumption waste materials generated in production activities of enterprises are used for reacting with sulfuric acid in the low-copper raffinate in advance, then the pre-neutralized low-copper raffinate is firstly extracted to recover copper, and then the raffinate is subjected to neutralization iron removal and cobalt precipitation production; the purposes of reducing consumption of alkaline auxiliary materials and production cost of a cobalt production system, improving the quality of cobalt salt, fully recycling copper in the low-copper raffinate, increasing the yield of cathode copper products and recycling waste materials are achieved, and the method has the advantages of being high in comprehensive utilization degree of resources, remarkable in economic benefit, simple in process and high in operability.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and in particular to a method for reducing sulfuric acid content in a low-copper raffinate and recovering copper. Background Art

[0002] In the prior art, copper-cobalt oxide ores are mostly produced using hydrometallurgical processes to produce cathode copper and crude cobalt hydroxide products. The main process flow is: crushing and grinding - stirring and leaching - CCD countercurrent washing - high and low copper extraction - electrolysis. The low-copper raffinate produced in the extraction process is used as the raw material for the production of crude cobalt hydroxide. It is subjected to the processes of neutralization and iron removal - first stage cobalt precipitation - second stage cobalt precipitation - flash drying to produce the cobalt salt product. Since the pH of copper and cobalt precipitation is similar, the low low-copper extraction rate will lead to an increase in the copper ion concentration in the low-copper raffinate. This part of copper enters the cobalt production system and will be precipitated into the iron-manganese slag and cobalt salt during the neutralization and iron precipitation and cobalt precipitation processes, resulting in copper loss and deterioration of the quality of the cobalt salt. With the gradual development and reduction of surface oxide ore resources, more and more mining companies have begun to develop deep sulfide ore resources. The smelting process of deep sulfide ore generally adopts the crushing and grinding-flotation-roasting-water quenching process. The water quenching liquid is mixed with the oxide ore leaching liquid to increase the copper content of the extracting liquid, which increases the sulfuric acid content and copper content of the raffinate produced by the extraction, increases the consumption of alkaline auxiliary materials in the subsequent cobalt precipitation process and deteriorates the quality of cobalt salts. Therefore, reducing the acidity and copper content of the low-copper raffinate is an issue that the copper-cobalt hydrometallurgical industry urgently needs to pay attention to and solve.

[0003] At present, the measures taken by the copper-cobalt hydrometallurgical industry to reduce the sulfuric acid concentration in the low-copper raffinate are often to reduce the sulfuric acid concentration in the leachate of the front-end leaching process, so that the sulfuric acid concentration of the influent is reduced, thereby reducing the sulfuric acid content in the low-copper raffinate. However, this method cannot reduce the acid production during the extraction process, especially for the influent with a high copper concentration.

[0004] In the prior art, there is a method for deep copper removal using a cobalt salt solution with a publication number of CN107032416B. The method first heats the pre-copper precipitation solution to 60-90°C, then adds a reagent synthesized from NaCS3, CoCl2 and second-stage copper precipitation slag for first-stage copper precipitation, and then adds cobalt thiosulfate for second-stage copper precipitation. Although the copper content of the solution after copper precipitation is less than 1 mg / L, the copper-cobalt ratio of the copper precipitation slag is 15 / 1, and the selective removal result of copper is not good. In addition, the use of heating measures and uncommon agents is not conducive to industrial application.

[0005] A Chinese patent with announcement number CN116732335A discloses a method for highly efficient selective copper precipitation from a cobalt-containing low-copper raffinate. The method uses a sulfiding agent and polysulfide to add to the low-copper raffinate for sulfidation copper precipitation. The obtained copper sulfide precipitate residue is filtered and dehydrated and then returned to the roasting-leaching process. Although the method achieves the selective separation and removal of copper in the low-copper raffinate, the produced copper sulfide precipitate residue has to be returned to the front-end process and then enter the wet process system, which lengthens the treatment process, increases the treatment cost and affects the copper recovery rate.

[0006] Therefore, it is particularly important to develop a process for reducing the sulfuric acid and copper content in low-copper raffinate that is economical, efficient, simple in process and easy to industrialize based on the actual production conditions of copper-cobalt mining enterprises. Summary of the invention

[0007] The object of the present invention is to provide a method for reducing the sulfuric acid content in a low-copper raffinate and recovering copper, so as to solve the problems raised in the above background technology.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A method for reducing sulfuric acid content in a low-copper raffinate and recovering copper, the method comprising the following steps:

[0010] Step S1, pre-neutralization: adding waste acid-consuming materials produced by the mining enterprise and unable to be effectively treated to the low-copper raffinate, starting stirring in the pre-neutralization tank to react, and consuming part of the sulfuric acid in the low-copper raffinate;

[0011] Step S2, thickening separation: the pre-neutralized solid-liquid mixed slurry is pumped into a deep cone thickener for thickening separation to obtain a thick overflow liquid and a thick underflow slag, respectively. The thick underflow slag is returned to the leaching-CCD countercurrent washing process, and the thick overflow liquid is subjected to the extraction and copper removal step;

[0012] Step S3, extraction and copper removal: the concentrated overflow liquid after pre-neutralization obtained in step S2 is subjected to single-stage extraction to recover copper in the pre-neutralized liquid. The single-stage extraction ratio is 0 / A of 0.1 to 5, and the concentration of the extractant is 5 to 25%. Since the sulfuric acid content of the pre-neutralized liquid is reduced, the copper extraction effect is improved. After extraction, the copper directly enters the electrowinning process to produce a cathode copper product, and the pre-neutralized liquid raffinate enters the neutralization and iron removal step;

[0013] Step S4, neutralization and iron removal: After the low-copper raffinate is pre-neutralized and extracted to remove copper, its sulfuric acid content and copper content are both low, and then the raffinate after pre-neutralization is subjected to neutralization and iron removal, cobalt precipitation and flash drying processes to finally obtain a cobalt salt product.

[0014] Preferably, in step S1, the waste acid-consuming materials produced by the mining enterprise and unable to be effectively treated refer to one or more of sulfide ore flotation tailings, oxide ore flotation tailings, mixed ore flotation tailings, high-acid-consuming ores or high-acid-consuming waste rocks.

[0015] It should be noted that the high-acid consumption ore mentioned above refers to the unprocessed raw ore with a high acid consumption value, not tailings; high-acid consumption waste rock refers to the waste rock with a high acid consumption value mined from mines or mines, which is often mined together with the ore; tailings refer to the remaining tailings after processing and extracting valuable metals.

[0016] Preferably, in step S1, the low-copper raffinate has a sulfuric acid content of 10 to 40 g / L and a copper content of 0.05 to 2 g / L, and the acid consumption value of the waste acid-consuming material is 100 to 1000 kg / t ore.

[0017] It should be noted that the acid consumption value mentioned above refers to the amount of sulfuric acid required to add water to a certain mass of ore to form a pulp, then add sulfuric acid to reduce the pH to the target pH and maintain it unchanged. The acid consumption value calculation method of the present invention is: a certain mass of ore is prepared into a pulp with a concentration of 30%, sulfuric acid is added to reduce the pH of the pulp to 1.5 and maintain it unchanged, and the ratio of the mass of sulfuric acid used to the mass of the ore.

[0018] Preferably, in step S1, the waste acid-consuming material is added in the form of solid dry powder, water-containing solid or solid slurry.

[0019] Preferably, in step S1, the liquid-to-solid ratio of the pre-neutralization reaction is 0.5-50, the reaction time is 0.5-4h, and the pH at the reaction endpoint is 1-3.

[0020] Preferably, in step S2, the concentrated overflow liquid has a sulfuric acid content of 1 to 10 g / L.

[0021] Preferably, in step S2, the thick underflow slag is returned to the leaching CCD countercurrent washing process, which is to return the thick underflow slag to any level of leaching tank or leaching thickener in the stirring leaching process and any level of CCD thickener.

[0022] Preferably, in step S3, the sulfuric acid content of the pre-neutralized raffinate is 1-20 g / L and the copper content is 0.005-0.1 g / L.

[0023] Preferably, in step S4, the cobalt salt product obtained through the iron removal, cobalt precipitation and flash drying process has an impurity copper content of less than 0.5%.

[0024] In summary, the beneficial effects of the present invention are:

[0025] In the present invention, the sulfuric acid content of the low-copper raffinate can be reduced by more than 50% before entering the neutralization and iron removal process, and the copper content can be reduced to below 0.1 g / L, thereby effectively reducing the consumption of alkaline auxiliary materials and production costs of the cobalt production system, while achieving the recovery of copper in the low-copper raffinate and the improvement of the quality of cobalt salts, thereby realizing the resource utilization of waste materials.

[0026] The invention is proposed based on the actual production situation of copper-cobalt mining enterprises, has the advantages of significant economic benefits, simple process, strong operability, high comprehensive utilization of resources, and is easy to realize industrial production and application.

[0027] The invention utilizes the waste acid-consuming materials produced by the mining enterprise and unable to be effectively treated to neutralize the waste acid-consuming materials with the low-copper raffinate in advance, extracts and recovers copper in the pre-neutralized low-copper raffinate, and then enters the subsequent iron removal and cobalt precipitation process. The method reduces the sulfuric acid content and copper content of the feed liquid entering the iron removal and cobalt precipitation process, saves the consumption of the alkaline auxiliary materials lime and magnesium oxide in the iron removal and cobalt precipitation process, and reduces the content of impurity copper in the cobalt salt product, thereby achieving the purpose of increasing the output of cathode copper products, reducing the production cost of cobalt salts, improving the quality of cobalt salts and resource utilization of waste materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention provides a schematic diagram of a process for reducing sulfuric acid content and recovering copper in a low-copper raffinate. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The production cost of the cobalt production system is mainly the cost of the alkaline auxiliary materials used in the iron removal and cobalt precipitation steps. In this specific embodiment, before the iron removal and cobalt precipitation steps, low-cost or even waste acid-consuming materials are used to pre-neutralize with the low-copper raffinate, and measures are taken to recover and remove copper in the low-copper raffinate to reduce the sulfuric acid content and copper content of the feed entering the iron removal and cobalt precipitation steps. This can reduce the consumption of alkaline auxiliary materials and the copper content of cobalt salt impurities, thereby reducing the production cost of cobalt salts and improving the quality of cobalt salts.

[0031] This specific embodiment provides a method for reducing sulfuric acid content and recovering copper in a low-copper raffinate, comprising the following steps:

[0032] Step S1, pre-neutralization: adding waste acid-consuming materials produced by the mining enterprise and unable to be effectively treated to the low-copper raffinate, starting stirring in the pre-neutralization tank to react, and consuming part of the sulfuric acid in the low-copper raffinate;

[0033] Step S2, thickening separation: the pre-neutralized solid-liquid mixed slurry is pumped into a deep cone thickener for thickening separation to obtain a thick overflow liquid and a thick underflow slag, respectively. The thick underflow slag is returned to the leaching-CCD countercurrent washing process, and the thick overflow liquid is subjected to the extraction and copper removal step;

[0034] Step S3, extraction and copper removal: the concentrated overflow liquid after pre-neutralization obtained in step S2 is subjected to single-stage extraction to recover copper in the pre-neutralized liquid. The single-stage extraction ratio is 0 / A of 0.1 to 5, and the concentration of the extractant is 5 to 25%. Since the sulfuric acid content of the pre-neutralized liquid is reduced, the copper extraction effect is improved. After extraction, the copper directly enters the electrowinning process to produce a cathode copper product, and the pre-neutralized liquid raffinate enters the neutralization and iron removal step;

[0035] Step S4, neutralization and iron removal: After the low-copper raffinate is pre-neutralized and extracted to remove copper, its sulfuric acid content and copper content are both low, and then the raffinate after pre-neutralization is subjected to neutralization and iron removal, cobalt precipitation and flash drying processes to finally obtain a cobalt salt product.

[0036] Furthermore, in step S1, the waste acid-consuming materials produced by the mining enterprise and unable to be effectively treated refer to one or more of sulfide ore flotation tailings, oxide ore flotation tailings, mixed ore flotation tailings, high-acid-consuming ores or high-acid-consuming waste rocks.

[0037] It should be noted that the high-acid consumption ore mentioned above refers to the unprocessed raw ore with a high acid consumption value, not tailings; high-acid consumption waste rock refers to the waste rock with a high acid consumption value mined from mines or mines, which is often mined together with the ore; tailings refer to the remaining tailings after processing and extracting valuable metals.

[0038] In some preferred implementations, in step S1, the sulfuric acid content of the low-copper raffinate is 10-40 g / L, the copper content is 0.05-2 g / L, and the acid consumption value of the waste acid-consuming material is 100-1000 kg / t ore.

[0039] It should be noted that the acid consumption value mentioned above refers to the amount of sulfuric acid required to add water to a certain mass of ore to form a pulp, then add sulfuric acid to reduce the pH to the target pH and maintain it unchanged. The acid consumption value calculation method of the present invention is: a certain mass of ore is prepared into a pulp with a concentration of 30%, sulfuric acid is added to reduce the pH of the pulp to 1.5 and maintain it unchanged, and the ratio of the mass of sulfuric acid used to the mass of the ore.

[0040] In some preferred embodiments, in step S1, the waste acid-consuming material is added in the form of solid dry powder, water-containing solid or solid slurry.

[0041] In some preferred embodiments, in step S1, the liquid-to-solid ratio of the pre-neutralization reaction is 0.5-50, the reaction time is 0.5-4h, and the pH at the reaction endpoint is 1-3.

[0042] In some preferred embodiments, in step S2, the concentrated overflow liquid has a sulfuric acid content of 1-10 g / L.

[0043] In some preferred embodiments, in step S2, the thick underflow slag is returned to the leaching CCD countercurrent washing process, which is to return the thick underflow slag to any level of leaching tank or leaching thickener in the stirring leaching process and any level of CCD thickener.

[0044] In some preferred embodiments, in step S3, the sulfuric acid content of the pre-neutralized raffinate is 1-20 g / L, and the copper content is 0.005-0.1 g / L.

[0045] In some preferred embodiments, in step S4, the cobalt salt product obtained through the iron removal, cobalt precipitation and flash drying process has an impurity copper content of less than 0.5%. Specific embodiment 1:

[0047] Take 2000mL of low-copper raffinate in a beaker, the initial pH value is 0.55, the main components are 0.61g / L copper, 2.81g / L cobalt, 1.22g / L manganese, 0.98g / L iron, 27.64g / L sulfuric acid, and the acid consumption value of the sulfide ore flotation tailings produced by the workshop is 350kg / t ore.

[0048] S1. Add the sulfide ore flotation tailings to the low copper raffinate at a liquid-to-solid ratio of 10, and start stirring at the same time to perform a pre-neutralization reaction. After 95 minutes of reaction time, the pH value is 1.35, and then filter the filtrate. The filtrate is sent for analysis and the sulfuric acid content is 5.92 g / L;

[0049] S2, the pre-neutralized filtrate is subjected to single-stage extraction to recover copper, the concentration of the extractant is 10% (v / v), the extraction ratio is 1, the extraction reaction time is 2min, and the raffinate of the pre-neutralized filtrate is obtained. The copper content of the raffinate of the pre-neutralized filtrate is 0.021g / L and the sulfuric acid content is 6.81g / L after testing;

[0050] S3, the raffinate of the pre-neutralized filtrate was added with lime powder for neutralization and iron removal reaction, the reaction endpoint pH was controlled to be 4.0, and the amount of lime was 10.16g;

[0051] S4. The de-ironized liquid is subjected to a cobalt precipitation reaction to obtain a cobalt hydroxide product precipitate, which is filtered, dried, and sent for analysis. The cobalt grade is 37.23% and the impurity copper content is 0.08%. Specific embodiment 2:

[0053] Take 2000mL of low-copper raffinate in a beaker, and the initial pH value is 0.49. The main components are 0.56g / L copper, 3.02g / L cobalt, 1.33g / L manganese, 1.25g / L iron, and 31.74g / L sulfuric acid. The acid consumption value of the high-acid consumption ore mined from the mine is 575kg / t ore.

[0054] S1. Add high acid consumption ore to low copper raffinate at a liquid-to-solid ratio of 12, and start stirring at the same time to perform a pre-neutralization reaction. After 82 minutes of reaction time, the pH value is 1.38, and then filter the filtrate. The filtrate is sent for analysis and the sulfuric acid content is 5.09 g / L;

[0055] S2, the pre-neutralization filtrate is subjected to single-stage extraction to recover copper, the concentration of the extractant is 8% (v / v), the extraction ratio is 1, the extraction reaction time is 2min, and the raffinate of the pre-neutralization filtrate is obtained. The copper content of the raffinate of the pre-neutralization filtrate is 0.015g / L and the sulfuric acid content is 5.92g / L after testing;

[0056] S3, adding lime powder to the raffinate of the pre-neutralized filtrate to carry out neutralization and iron removal reaction, controlling the reaction end point pH to 4.0, and the amount of lime to be 8.63g;

[0057] S4. The de-ironized liquid is subjected to a cobalt precipitation reaction to obtain a cobalt hydroxide product precipitate, which is filtered, dried, and sent for analysis. The cobalt grade is 39.57% and the impurity copper content is 0.06%.

[0058] Comparative Example 1:

[0059] Compared with the specific embodiment 1, the low copper raffinate used is the same solution, the difference is that the neutralization and iron removal process is directly carried out without the pre-neutralization and extraction copper removal process, the operation and conditions of the neutralization and iron removal process are carried out according to the operation of the specific embodiment 1, the reaction end pH is controlled to be 4.0, the amount of lime is 33.16g, the copper content of the neutralized and iron removal liquid is 0.23g / L, and then the neutralized and iron removal liquid is subjected to the cobalt precipitation process in the same operation as in the embodiment 1, and finally the cobalt hydroxide product precipitate is obtained, filtered, dried and sent for analysis, and the cobalt grade is 33.57% and the impurity copper content is 3.02%. It can be seen from the comparative example 1 that if the low copper raffinate is not pre-neutralized and extracted copper removal process, the lime consumption of the neutralization and iron removal process will be greatly pushed up, and the quality of the cobalt salt will be deteriorated and the copper metal will be lost.

[0060] Table 4 Specific Example 2 and the results of Comparative Example 1

[0061] project Cobalt Grade Impurity copper content Specific embodiment 1 37.23％ 0.08％ Specific embodiment 2 39.57％ 0.06％ Comparative Example 1 33.57％ 3.02％

[0062] The present invention does not elaborate on some of the well-known technologies that belong to those skilled in the art.

[0063] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

[0064] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for reducing sulfuric acid content and recovering copper in a low-copper raffinate, characterized in that: The method comprises the following steps: Step S1, pre-neutralization: adding waste acid-consuming materials to the low-copper raffinate, starting stirring in the pre-neutralization tank to react, and consuming part of the sulfuric acid in the low-copper raffinate; Step S2, thickening separation: the pre-neutralized solid-liquid mixed slurry is pumped into a deep cone thickener for thickening separation to obtain a thick overflow liquid and a thick underflow slag, respectively. The thick underflow slag is returned to the leaching CCD countercurrent washing process, and the thick overflow liquid is subjected to the extraction and copper removal step; Step S3, extraction and copper removal: the concentrated overflow liquid after pre-neutralization obtained in step S2 is subjected to single-stage extraction to recover copper in the pre-neutralized liquid. The single-stage extraction ratio is 0 / A of 0.1-5, and the concentration of the extractant is 5-25%. After extraction, the copper directly enters the electrowinning process to produce a cathode copper product, and the pre-neutralized liquid raffinate enters the neutralization and iron removal step; Step S4, neutralization and iron removal: the raffinate of the pre-neutralized liquid is subjected to the steps of neutralization and iron removal, cobalt precipitation and flash drying to finally obtain a cobalt salt product.

2. The method for reducing sulfuric acid content and recovering copper in a low-copper raffinate according to claim 1, characterized in that: In step S1, the waste acid-consuming materials refer to one or more of sulfide ore flotation tailings, oxide ore flotation tailings, mixed ore flotation tailings, high acid-consuming ores or high acid-consuming waste rocks.

3. The method for reducing sulfuric acid content and recovering copper in a low-copper raffinate according to claim 1, characterized in that: In the step S1, the low-copper raffinate has a sulfuric acid content of 10-40 g / L and a copper content of 0.05-2 g / L, and the acid consumption value of the waste acid-consuming materials is 100-1000 kg / t ore.

4. The method for reducing sulfuric acid content and recovering copper in a low-copper raffinate according to claim 1, characterized in that: In the step S1, the waste acid-consuming material is added in the form of solid dry powder, water-containing solid or solid slurry.

5. The method for reducing sulfuric acid content and recovering copper in a low-copper raffinate according to claim 1, characterized in that: In the step S1, the liquid-to-solid ratio of the pre-neutralization reaction is 0.5-50, the reaction time is 0.5-4 hours, and the pH at the reaction end point is 1-3.

6. The method for reducing sulfuric acid content and recovering copper in a low-copper raffinate according to claim 1, characterized in that: In step S2, the concentrated overflow liquid has a sulfuric acid content of 1-10 g / L.

7. The method for reducing sulfuric acid content and recovering copper in a low-copper raffinate according to claim 1, characterized in that: In step S2, the thick underflow slag is returned to the leaching-CCD countercurrent washing process, which is to return the thick underflow slag to any level of leaching tank, leaching thickener or any level of CCD thickener in the stirring leaching process.

8. The method for reducing sulfuric acid content and recovering copper in a low-copper raffinate according to claim 1, characterized in that: In the step S3, the sulfuric acid content of the pre-neutralized raffinate is 1-20 g / L, and the copper content is 0.005-0.1 g / L.

9. The method for reducing sulfuric acid content and recovering copper in a low-copper raffinate according to claim 1, characterized in that: In the step S4, the cobalt salt product obtained through the iron removal, cobalt precipitation and flash drying process has an impurity copper content of less than 0.5%.

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