Method for recovering valuable metals in copper smelting slow-cooling slag copper separation tailings

Abstract

The invention discloses a method for recovering valuable metals in copper smelting slow-cooling slag copper separation tailings, and belongs to the technical field of hydrometallurgy. According to the method, the oxygen pressure leaching condition is controlled, sulfuric acid and lignosulfonate are added into the copper smelting slow-cooling slag copper separation tailings slurry, Cu and Zn in the slow-cooling slag copper separation tailings are synergistically promoted to be transferred into the leaching solution from solid phases in the slag, leaching of impurities such as Fe and Si is inhibited, and therefore high-selectivity recovery of valuable elements Cu and Zn in the slow-cooling slag is achieved; and finally, Cu and Zn are separated through a step-by-step extraction method, and Fe is separated from leaching residues through a magnetic separation technology. The problem that valuable metal existing in a more stable form in the copper smelting slow-cooling slag copper separation tailing slurry is difficult to recover is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy, and in particular relates to a method for recovering valuable metals in copper smelting slow cooling slag copper tailings. Background Art

[0002] With the progress of science and technology and the needs of social life, my country's refined copper output has shown an upward trend year by year, reaching 10.49 million tons in 2021, a year-on-year increase of 7.4%, accounting for about 40% of the global total output. Depending on the grade of copper concentrate and the composition of gangue, the amount of copper slag produced during the smelting process can reach 2 to 3 tons for every ton of metallic copper produced. Copper slag usually contains a variety of valuable elements, of which the copper content is about 0.5% to 2.7%, the iron content is about 30% to 45%, and the zinc content is about 1.0% to 3.0%. Due to the high value of copper, slow cooling-flotation or pyrometallurgical depletion technology is mainly used in industry to treat copper slag. In contrast, the beneficiation method has the characteristics of low energy consumption, low environmental pollution, high recovery rate and large enrichment ratio. It has unique advantages in both energy saving and environmental protection, and has been widely used in the domestic copper smelting industry. It is worth noting that copper flotation tailings still contain a variety of valuable elements such as zinc, copper and iron, especially the iron content is much higher than the optional boundary grade of iron ore in my country (>27%). With my country's dependence on foreign iron ore as high as 75%, the resource utilization of copper flotation tailings has become a research hotspot in the field of bulk solid waste in recent years. Compared with high-energy-consuming high-temperature reduction or oxidation technologies, the use of hydrometallurgical technology to treat copper slag can achieve the leaching of valuable elements such as copper in the original ore under low-energy consumption conditions. However, the occurrence state of Cu, Zn, and Fe in copper smelting slag copper tailings is significantly different from that in the original ore. Cu in copper smelting slag copper tailings is mainly present in the form of silicates and copper arsenide, Zn is mainly in the form of ferrites and silicates, and Fe is mainly in the form of iron olivine, magnetite, etc., which are difficult to recover by traditional wet leaching methods. In addition, copper smelting slag copper tailings also contain other complex impurities, and the existence form of impurities is also different from that of the original ore. How to achieve high-selective recovery of Cu, Zn, and Fe is also a difficulty that traditional wet leaching methods cannot overcome. Summary of the invention

[0003] In view of the above-mentioned shortcomings of the prior art, the present invention provides a method for recovering valuable metals in copper smelting slow cooling slag copper tailings.

[0004] To achieve the above object, the technical solution adopted by the present invention is:

[0005] A method for recovering valuable metals in copper smelting slow cooling slag copper tailings, comprising the following steps:

[0006] (1) Slurrying copper tailings from copper smelting slow cooling slag is then added with sulfuric acid and lignin sulfonate to obtain a mixed slurry;

[0007] (2) subjecting the mixed slurry to oxygen pressure leaching to achieve solid-liquid separation, thereby obtaining leaching residue and leaching liquid;

[0008] (3) adding a first extractant to the leachate to extract Cu, and separating the first aqueous phase and the first organic phase;

[0009] (4) stripping the first organic phase, separating the stripped second aqueous phase and the second organic phase, returning the obtained second organic phase to the Cu extraction in step (3), and performing a purification electrolysis process on the obtained second aqueous phase;

[0010] (5) adding the second extractant to the first aqueous phase to extract Zn, and separating the third aqueous phase and the third organic phase;

[0011] (6) The third organic phase is stripped, and the fourth aqueous phase and the fourth organic phase after stripping are separated. The obtained fourth organic phase is returned to the Zn extraction in step (5) for use, and the fourth aqueous phase is subjected to a purification electrolysis process.

[0012] The third aqueous phase obtained in step (5) is returned to step (1) as slurry preparation water for reducing the copper smelting slow cooling slag copper tailings.

[0013] The second aqueous phase and the fourth aqueous phase are subjected to a purification electrolysis process to separate copper and zinc respectively. The purification electrolysis process adopts a conventional purification electrolysis process in the art to extract copper and zinc respectively.

[0014] The copper smelting slow cooling slag copper tailings include the following components in percentage by mass: Cu: 0.15-0.3%, Zn: 2.5-5%, Fe: 40-50%, SiO2: 20-30%.

[0015] As a preferred embodiment of the present invention, in the mixed slurry, the mass concentration of sulfuric acid is 50-150 g / l, the mass percentage of lignin sulfonate is 0.1%-0.5%; the lignin sulfonate is at least one of sodium lignin sulfonate, calcium lignin sulfonate, potassium lignin sulfonate, and iron lignin sulfonate. If the amount of sulfuric acid and lignin sulfonate added is not within the scope of the present invention, the high selectivity leaching of Cu and Zn will be significantly reduced.

[0016] As a preferred embodiment of the present invention, the oxygen pressure of the oxygen pressure leaching is 1.8-2.2MPa, the temperature is 150-220°C, and the time is 60-180min. Low oxygen pressure leaching temperature and pressure will result in the formation of a large amount of silica gel, which will make it difficult to leach valuable metals, and will also affect the occurrence form of Fe in the leached residue, thereby affecting the recovery of Fe; high oxygen pressure leaching temperature and pressure will result in a large amount of Fe and Si entering the leaching solution, affecting the subsequent extraction process.

[0017] As a preferred embodiment of the present invention, the first extractant is extractant A and kerosene; the ratio of extractant A to kerosene is 15%-50%:85%-50%; extractant A is at least one of Lix63, Lix64, Lix65N, Lix984, Lix84, and M5640.

[0018] As a preferred embodiment of the present invention, the parameters of the Cu extraction are: temperature of 15-40°C, time of 3-20 min, relative O / A=(1-3):(1-4), pH=1-3.

[0019] As a preferred embodiment of the present invention, in step (4), the stripping parameters are: temperature of 15-40°C, time of 2-10 min, ratio O / A=(0.5-1.5):1, and acidity of 160-200 g / l.

[0020] As a preferred embodiment of the present invention, the parameters of the Zn extraction are: temperature of 20-35°C, time of 5-30 min, ratio O / A=(1-4):(1-3), pH=3-5.

[0021] As a preferred embodiment of the present invention, in step (6), the stripping parameters are: temperature of 15-40°C, time of 2-10 min, ratio O / A=(0.5-1.5):1, and acidity of 100-150 g / l.

[0022] As a preferred embodiment of the present invention, the second extractant is extractant B and kerosene; the ratio of extractant B to kerosene is 15%-50%:85%-50%; extractant A is at least one of di(2-ethylhexyl) phosphate, 2-ethylhexyl mono(2-ethylhexyl) phosphate, and Cyanex272.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: in order to solve the difficulty of recovering the valuable metals in a more stable form in the copper smelting slow cooling slag copper tailings slurry, the present invention controls the oxygen pressure leaching conditions and adds sulfuric acid and lignin sulfonate to the copper smelting slow cooling slag copper tailings slurry, synergistically promotes the transfer of Cu and Zn in the slow cooling slag copper tailings from the solid phase in the slag to the leachate, and inhibits the leaching of impurities such as Fe and Si, thereby achieving high selective recovery of the valuable elements Cu and Zn in the slow cooling slag, and is more conducive to the subsequent separation of Cu and Zn by the step-by-step extraction method. In addition, by adding sulfuric acid and lignin sulfonate to the copper smelting slow cooling slag copper tailings slurry and combining with oxygen pressure leaching technology, the proportion of magnetic iron in the leached slag is significantly increased, which is more conducive to the subsequent magnetic separation of Fe. DETAILED DESCRIPTION

[0024] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0025] Example 1

[0026] A method for recovering valuable metals in copper smelting slow cooling slag copper tailings, comprising the following steps:

[0027] (1) 143 g of copper smelting slow cooling slag copper tailings were taken, 1000 ml of water was added to the slurry, the sulfuric acid concentration in the slurry was 120 g / l, and 0.3% by weight of sodium lignin sulfonate was added to the slurry; the slurry was placed in a reactor, and oxygen pressure acid leaching was carried out at an oxygen pressure of 2 MPa, a stirring speed of 600 r / min, a reaction temperature of 200°C, and a reaction time of 120 min.

[0028] (2) After leaching is completed, solid-liquid separation is performed to achieve efficient leaching of Cu and Zn; the leaching residue and leaching liquid are sent for analysis, and the calculated leaching rate of Cu is 90.47%, the leaching rate of Zn is 77.03%, and the sediment rate of Fe is 88.99%. Si is retained in the residue in the form of silicate and silica gel, and is basically not leached.

[0029] (3) Take 500 ml of the leaching solution obtained in step (2), add the first extractant to extract Cu, and perform the extraction at a temperature of 25°C, a time of 20 min, a phase O / A of 2:1, and a pH of 2.5. After the extraction is completed, separate the aqueous phase and the organic phase, and enter the Zn extraction process. The organic phase is stripped at a temperature of 25°C, a time of 5 min, a phase O / A of 0.5:1, and an acidity of 180 g / l. The first extractant is Lix63 and kerosene; the volume ratio of Lix63 and kerosene is 50%:50%.

[0030] (4) After the stripping is completed, the aqueous phase and the organic phase are separated, and the obtained organic phase is returned to the Cu extraction process for use. The aqueous phase is sent for sample analysis of the Cu content, and the Cu extraction rate is calculated to be 96.26%. The aqueous phase enters the subsequent purification electrolysis process.

[0031] (5) 400 ml of the aqueous phase obtained after the extraction in step (3) is taken, and a second extractant is added to extract zinc. The extraction is carried out at a temperature of 25° C., a time of 20 min, a phase O / A of 3:1, and a pH of 3.5. After the extraction is completed, the aqueous phase and the organic phase are separated, and the organic phase is stripped at a temperature of 25° C., a time of 5 min, a phase O / A of 1:1, and an acidity of 120 g / l. After the stripping is completed, the aqueous phase and the organic phase are separated, and the obtained organic phase is returned to the Zn extraction process for use. The Zn content of the aqueous phase is analyzed, and the Zn extraction rate is calculated to be 83.54%. The aqueous phase enters the subsequent purification electrolysis process. The second extractant is di(2-ethylhexyl) phosphate and kerosene; the ratio of di(2-ethylhexyl) phosphate to kerosene is 15%:85%.

[0032] Example 2

[0033] A method for recovering valuable metals in copper smelting slow cooling slag copper tailings, comprising the following steps:

[0034] (1) 143 g of copper smelting slow cooling slag copper tailings were taken, 1000 ml of water was added to the slurry, the sulfuric acid concentration in the slurry was 50 g / l, and 0.5% by weight of calcium lignin sulfonate was added to the slurry; the slurry was placed in a reactor, and oxygen pressure acid leaching was carried out at an oxygen pressure of 1.8 MPa, a stirring speed of 700 r / min, a reaction temperature of 220°C, and a reaction time of 180 min.

[0035] (2) After leaching is completed, solid-liquid separation is performed to achieve efficient leaching of Cu and Zn; the leaching residue and leaching liquid are sent for analysis, and the calculated leaching rate of Cu is 91.85%, the leaching rate of Zn is 78.03%, and the sediment rate of Fe is 89.73%. Si is retained in the residue in the form of silicate and silica gel, and is basically not leached.

[0036] (3) Take 500 ml of the leaching solution obtained in step (2), add the first extractant to extract Cu, and perform the extraction at a temperature of 40°C, a time of 3 min, a phase O / A of 3:4, and a pH of 1. After the extraction is completed, separate the aqueous phase and the organic phase, and the aqueous phase enters the Zn extraction process. The organic phase is stripped at a temperature of 15°C, a time of 10 min, a phase O / A of 1.5:1, and an acidity of 160 g / l. The first extractant is Lix64 and kerosene; the ratio of Lix64 to kerosene is 15%:85%.

[0037] (4) After the stripping is completed, the aqueous phase and the organic phase are separated, the obtained organic phase is returned to the Cu extraction process, and the aqueous phase is sent for analysis of the Cu content. The Cu extraction rate is calculated to be 95.28%, and the aqueous phase enters the subsequent purification electrolysis process.

[0038] (5) 400 ml of the aqueous phase obtained after the extraction in step (3) is taken, and a second extractant is added to extract zinc. The extraction is carried out at a temperature of 20° C., a time of 30 min, a phase O / A of 4:3, and a pH of 5. After the extraction is completed, the aqueous phase and the organic phase are separated, and the organic phase is stripped at a temperature of 40° C., a time of 2 min, a phase O / A of 1.5:1, and an acidity of 100 g / l. After the stripping is completed, the aqueous phase and the organic phase are separated, and the obtained organic phase is returned to the Zn extraction process for use. The Zn content of the aqueous phase is analyzed, and the Zn extraction rate is calculated to be 85.64%. The aqueous phase enters the subsequent purification electrolysis process. The second extractant is 2-ethylhexyl mono(2-ethylhexyl) phosphate and kerosene; the ratio of 2-ethylhexyl mono(2-ethylhexyl) phosphate to kerosene is 35%:65%.

[0039] Example 3

[0040] A method for recovering valuable metals in copper smelting slow cooling slag copper tailings, comprising the following steps:

[0041] (1) 143 g of copper smelting slow cooling slag copper tailings were taken, 1000 ml of water was added to the slurry, the sulfuric acid concentration in the slurry was 150 g / l, and 0.1% by weight of potassium lignin sulfonate was added to the slurry; the slurry was placed in a reactor, and oxygen pressure acid leaching was carried out at an oxygen pressure of 2.2 MPa, a stirring speed of 500 r / min, a reaction temperature of 150°C, and a reaction time of 60 min.

[0042] (2) After leaching is completed, solid-liquid separation is performed to achieve efficient leaching of Cu and Zn; the leaching residue and leaching liquid are sent for analysis, and the calculated leaching rate of Cu is 90.74%, the leaching rate of Zn is 79.01%, and the sediment rate of Fe is 87.54%. Si is retained in the residue in the form of silicate and silica gel, and is basically not leached.

[0043] (3) Take 500 ml of the leaching solution obtained in step (2), add the first extractant to extract Cu, and perform the extraction at a temperature of 15°C, a time of 20 min, a phase O / A of 1:1, and a pH of 3. After the extraction is completed, separate the aqueous phase and the organic phase, and the aqueous phase enters the Zn extraction process. The organic phase is stripped at a temperature of 40°C, a time of 2 min, a phase O / A of 1.2:1, and an acidity of 200 g / l. The first extractant is Lix65N and kerosene; the ratio of Lix65N to kerosene is 25%:75%.

[0044] (4) After the stripping is completed, the aqueous phase and the organic phase are separated, and the obtained organic phase is returned to the Cu extraction process for use. The aqueous phase is sent for sample analysis of the Cu content, and the Cu extraction rate is calculated to be 94.52%. The aqueous phase enters the subsequent purification electrolysis process.

[0045] (5) 400 ml of the aqueous phase obtained after the extraction in step (3) was taken, and a second extractant was added to extract zinc. The extraction was carried out at a temperature of 35°C, a time of 5 min, a phase O / A of 1:1, and a pH of 3. After the extraction was completed, the aqueous phase and the organic phase were separated. The organic phase was stripped at a temperature of 15°C, a time of 10 min, a phase O / A of 0.5:1, and an acidity of 150 g / l. After the stripping was completed, the aqueous phase and the organic phase were separated, and the obtained organic phase was returned to the Zn extraction process for use. The Zn content of the aqueous phase was analyzed, and the Zn extraction rate was calculated to be 86.53%. The aqueous phase entered the subsequent purification electrolysis process. The second extractant was Cyanex272 and kerosene; the ratio of Cyanex272 to kerosene was 50%:50%.

[0046] Comparative Example 1

[0047] A method for recovering valuable metals in copper smelting slow cooling slag copper tailings, comprising the following steps:

[0048] (1) Take 200g of copper smelting slow cooling slag copper tailings, add 1000ml of water to make slurry, the sulfuric acid concentration in the slurry is 112g / l, and add 0.3% of sodium lignin sulfonate to the slurry; put the slurry into a reactor, and carry out oxygen pressure acid leaching at an oxygen pressure of 1Mpa, a stirring speed of 600r / min, a reaction temperature of 120°C, and a reaction time of 600min.

[0049] (2) After leaching is completed, solid-liquid separation is performed to achieve the leaching of Cu and Zn; the leaching residue and leaching liquid are sent for analysis, and the calculated leaching rate of Cu is 67%, the leaching rate of Zn is 55.45%, and the sediment rate of Fe is 86.73%. A small amount of Si is leached, and the leaching amount is less than 5%.

[0050] (3) Take 500 ml of the leaching solution obtained in step (2), add the first extractant to extract Cu, and perform the extraction at a temperature of 25°C, a time of 20 min, a phase O / A of 1:1, and a pH of 2. After the extraction is completed, separate the aqueous phase and the organic phase, and enter the Zn extraction process. The organic phase is stripped at a temperature of 25°C, a time of 5 min, a phase O / A of 0.5:1, and an acidity of 160 g / l. The first extractant is Lix63 and kerosene; the volume ratio of Lix63 and kerosene is 50%:50%.

[0051] (4) After the stripping is completed, the aqueous phase and the organic phase are separated, and the obtained organic phase is returned to the Cu extraction process for use. The aqueous phase is sent for sample analysis of the Cu content, and the Cu extraction rate is calculated to be 75.14%. The aqueous phase enters the subsequent purification electrolysis process.

[0052] (5) 400 ml of the raffinate obtained in step (3) was taken, and a second extractant was added to extract zinc. The extraction was carried out at a temperature of 25° C., a time of 20 min, a phase O / A of 2:1, and a pH of 3. After the extraction was completed, the aqueous phase and the organic phase were separated. The organic phase was stripped at a temperature of 25° C., a time of 5 min, a phase O / A of 1:1, and an acidity of 100 g / l. After the stripping was completed, the aqueous phase and the organic phase were separated, and the obtained organic phase was returned to the Zn extraction process for use. The Zn content of the aqueous phase was analyzed, and the Zn extraction rate was calculated to be 61.55%. The aqueous phase entered the subsequent purification electrolysis process. The second extractant was di(2-ethylhexyl) phosphate and kerosene; the ratio of di(2-ethylhexyl) phosphate to kerosene was 15%:85%.

[0053] Comparative Example 2

[0054] A method for recovering valuable metals in copper smelting slow cooling slag copper tailings, comprising the following steps:

[0055] (1) 143 g of copper smelting slow cooling slag copper tailings were taken, 1000 ml of water was added to prepare slurry, and the sulfuric acid concentration in the slurry was 120 g / l; the slurry was placed in a reactor, and oxygen pressure acid leaching was carried out at an oxygen pressure of 2 MPa, a stirring speed of 600 r / min, a reaction temperature of 200°C, and a reaction time of 120 min.

[0056] (2) After leaching is completed, solid-liquid separation is performed to achieve the leaching of Cu and Zn; the leaching residue and leaching liquid are sent for analysis, and the calculated leaching rate of Cu is 57%, the leaching rate of Zn is 41.56%, the sediment rate of Fe is 70.81%, and a small amount of Si is leached, and the leaching amount is less than 5%.

[0057] (3) Take 500 ml of the leaching solution obtained in step (2), add the first extractant to extract Cu, and perform the extraction at a temperature of 25°C, a time of 20 min, a phase O / A of 2:1, and a pH of 2.5. After the extraction is completed, separate the aqueous phase and the organic phase, and enter the Zn extraction process. The organic phase is stripped at a temperature of 25°C, a time of 5 min, a phase O / A of 0.5:1, and an acidity of 180 g / l. The first extractant is Lix63 and kerosene; the volume ratio of Lix63 and kerosene is 50%:50%.

[0058] (4) After the stripping is completed, the aqueous phase and the organic phase are separated, and the obtained organic phase is returned to the Cu extraction process for use. The aqueous phase is sent for sample analysis of the Cu content, and the Cu extraction rate is calculated to be 76.85%. The aqueous phase enters the subsequent purification electrolysis process.

[0059] (5) 400 ml of the raffinate obtained in step (3) was taken, and a second extractant was added to extract zinc. The extraction was carried out at a temperature of 25° C., a time of 20 min, a phase O / A of 3:1, and a pH of 3.5. After the extraction was completed, the aqueous phase and the organic phase were separated. The organic phase was stripped at a temperature of 25° C., a time of 5 min, a phase O / A of 1:1, and an acidity of 120 g / l. After the stripping was completed, the aqueous phase and the organic phase were separated, and the obtained organic phase was returned to the Zn extraction process for use. The Zn content of the aqueous phase was analyzed, and the Zn extraction rate was calculated to be 64.77%. The aqueous phase entered the subsequent purification electrolysis process. The second extractant was di(2-ethylhexyl) phosphate and kerosene; the ratio of di(2-ethylhexyl) phosphate to kerosene was 15%:85%.

[0060] Comparative Example 3

[0061] A method for recovering valuable metals in copper smelting slow cooling slag copper tailings, comprising the following steps:

[0062] (1) 143 g of copper smelting slow cooling slag copper tailings were taken, 1000 ml of water was added to the slurry, and 0.3% by weight of sodium lignin sulfonate was added to the slurry; the slurry was placed in a reactor, and oxygen pressure acid leaching was carried out at an oxygen pressure of 2 MPa, a stirring speed of 600 r / min, a reaction temperature of 200°C, and a reaction time of 120 min.

[0063] (2) After leaching, solid-liquid separation was performed, and the leaching residue and leaching liquid were sent for analysis. Cu and Zn were almost undetectable in the solution and could not be leached.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for recovering valuable metals from copper smelting slow cooling slag copper tailings, characterized in that: The steps include: (1) Slurrying copper tailings from copper smelting slow cooling slag is then added with sulfuric acid and lignin sulfonate to obtain a mixed slurry; (2) subjecting the mixed slurry to oxygen pressure leaching to achieve solid-liquid separation, thereby obtaining leaching residue and leaching liquid; (3) adding a first extractant to the leachate to extract Cu, and separating the first aqueous phase and the first organic phase; (4) stripping the first organic phase, separating the stripped second aqueous phase and the second organic phase, returning the obtained second organic phase to the Cu extraction in step (3) to obtain the second aqueous phase for purification electrolysis process; (5) adding the second extractant to the first aqueous phase to extract Zn, and separating the third aqueous phase and the third organic phase; (6) The third organic phase is stripped, and the fourth aqueous phase and the fourth organic phase after stripping are separated. The obtained fourth organic phase is returned to the Zn extraction in step (5) for use, and the fourth aqueous phase is subjected to a purification electrolysis process.

2. The method for recovering valuable metals from copper smelting slow cooling slag copper tailings according to claim 1, characterized in that: In the mixed slurry, the mass concentration of sulfuric acid is 50-150 g / l, the mass percentage of lignin sulfonate is 0.1%-0.5%; the lignin sulfonate is at least one of sodium lignin sulfonate, calcium lignin sulfonate, potassium lignin sulfonate and iron lignin sulfonate.

3. The method for recovering valuable metals from copper smelting slow cooling slag copper tailings as claimed in claim 1, characterized in that: The oxygen pressure leaching is performed at an oxygen pressure of 1.8-2.2 MPa, a temperature of 150-220° C., and a time of 60-180 min.

4. The method for recovering valuable metals from copper smelting slow cooling slag copper tailings as claimed in claim 1, characterized in that: The first extractant is extractant A and kerosene; the volume ratio of extractant A and kerosene is (15%-50%): (85%-50%); extractant A is at least one of Lix63, Lix64, Lix65N, Lix984, Lix84, and M5640.

5. The method for recovering valuable metals from copper smelting slow cooling slag copper tailings as claimed in claim 1, characterized in that: In the step (3), the temperature of Cu extraction is 15-40°C, the time is 3-20 min, the ratio O / A=(1-3):(1-4), and pH=1-3.

6. The method for recovering valuable metals from copper smelting slow cooling slag copper tailings as claimed in claim 1, characterized in that: In the step (4), the stripping temperature is 15-40° C., the stripping time is 2-10 min, the ratio O / A is (0.5-1.5): 1, and the acidity is 160-200 g / l.

7. The method for recovering valuable metals from copper smelting slow cooling slag copper tailings as claimed in claim 1, characterized in that: In the step (5), the temperature of Zn extraction is 20-35°C, the time is 5-30 min, the ratio O / A is (1-4): (1-3), and the pH is 3-5.

8. The method for recovering valuable metals from copper smelting slow cooling slag copper tailings as claimed in claim 1, characterized in that: In the step (6), the stripping temperature is 15-40° C., the time is 2-10 min, the ratio O / A=(0.5-1.5):1, and the acidity is 100-150 g / l.

9. The use of the silicon wafer cleaning agent as claimed in claim 8 in cleaning solar cell silicon wafers before texturing, characterized in that: The second extractant is extractant B and kerosene; the volume ratio of extractant B to kerosene is 15%-50%:85%-50%; extractant B is one or more of di(2-ethylhexyl) phosphate, 2-ethylhexyl mono(2-ethylhexyl) phosphate, and Cyanex272.