A copper selection process for iron-containing waste residues

Abstract

The application provides a copper selection process of iron-containing waste residue, and comprises the following steps: adding iron powder and ammonium fluoride into titanium dioxide waste acid to obtain a titanium dioxide waste acid pre-solution after a period of reaction; S2, adding the iron-containing waste residue into the titanium dioxide waste acid pre-solution, and controlling the reaction temperature to be 20-50 DEG C; S3, after the reaction is completed, adding a nano precipitant when the pH of the solution is adjusted to 3-4.5, and adding a modified flocculating agent after a period of reaction, so that the precipitated copper is obtained after filtration and washing.

Description

Technical Field

[0001] This invention relates to the field of waste residue treatment technology, and more specifically, to a copper extraction process for iron-containing waste residue. Background Technology

[0002] China has become a major global producer of copper, zinc, and titanium dioxide. The copper-zinc smelting and titanium dioxide acidolysis processes generate large amounts of waste slag. These slags cannot be disposed of in slag dumps, and stockpiling not only occupies land resources but also releases heavy metals such as Pb and Cr from the slag due to environmental changes. The slag contains significant amounts of copper, and its disposal results in substantial resource waste and environmental pollution. Efficiently recovering copper from the slag is crucial for the economic benefits of enterprises and for eliminating the potential for secondary heavy metal pollution from slag dumps. Therefore, resource-based treatment is the only way for the sustainable development of industries dealing with waste slag such as iron slag, copper slag, and titanium slag. Summary of the Invention

[0003] The purpose of this invention is to provide a copper extraction process for iron-containing waste slag, which uses titanium dioxide waste acid to leach copper from the iron-containing waste slag, and then uses a nano-precipitant to precipitate copper from the leachate, thus treating waste with waste, enabling resource recycling and bringing greater economic benefits to enterprises.

[0004] The embodiments of the present invention are achieved through the following technical solutions:

[0005] A copper beneficiation process for iron-containing waste slag includes the following steps:

[0006] S1. Iron powder and ammonium fluoride are added to titanium dioxide waste acid and reacted for a period of time to obtain a titanium dioxide waste acid pre-solution. The pH of the solution is adjusted to about 4.0 using iron powder and ammonium fluoride, thereby removing titanium from the waste acid. At the same time, the iron powder can also reduce ferric ions, reducing iron loss and avoiding the introduction of other impurities into the waste acid solution. This not only allows for the integration and reuse of waste acid and the removal of impurities, but also facilitates the subsequent leaching of copper from iron-containing waste slag.

[0007] S2. Add 100g of iron-containing waste residue to 300mL of titanium dioxide waste acid pre-solution with sulfuric acid concentration of 120-130g / L (liquid-solid ratio of 1:1.5-4). The reaction temperature is 20-50℃, preferably controlled at 30℃. The reaction time is 2-5h. After the reaction is completed, filter the residue and wash it repeatedly in countercurrent. Combine the leachate with the washing water, neutralize it with lime milk, and then perform solid-liquid separation to remove trivalent iron and heavy metals such as zinc.

[0008] S3. When the pH of the solution is adjusted to 3-4.5, add 1.5-2 times the amount of nano-precipitant to the filtrate. After reacting for 0.5-1.5 hours, add the modified flocculant. After filtration and washing, precipitated copper is obtained.

[0009] Furthermore, the nano-precipitant is a combination of soluble sulfate and sulfur. When the nano-precipitant of the present invention is added to the filtrate, its reactivity can be improved, thereby enabling it to undergo various chemical and physical reactions with copper more efficiently, such as precipitation, co-precipitation, and surface adsorption, thus precipitating copper more efficiently. Moreover, the nano-precipitant of the present invention can better avoid sulfur residue and reduce the loss of ferrous sulfate in waste acid, so that ferrous sulfate can be efficiently recycled and reused.

[0010] Furthermore, the preparation method of the nano-active precipitant is as follows: soluble sulfate and sodium sulfide are dissolved separately in sodium chloride solution, and then the two solutions are mixed, filtered, washed and dried to obtain nano-powder material.

[0011] Furthermore, the soluble sulfate includes potassium sulfate or ammonium sulfate, preferably ammonium sulfate. In removing impurities from ferrous sulfate in the filtrate, this invention avoids using solutions containing sodium ions, as this would introduce Na ions into the waste acid, causing excessive Na impurities and hindering impurity removal.

[0012] Furthermore, the modified flocculant is acrylamide grafted with hydroxyl or carboxyl groups. By introducing active groups, it has better flocculation performance and can accelerate ion sedimentation.

[0013] Further, the preparation method of the modified acrylamide involves graft copolymerization of chitosan, nano-silica, and acrylamide, specifically including the following steps: a certain mass of chitosan, nano-silica powder, and acrylamide (mass ratio 1:1-2:4-5) is fully dissolved in a 1% acetic acid solution. Under a nitrogen atmosphere, cerium ammonium nitrate initiator is added, and after stirring evenly, a reverse emulsion polymerization method is used. The reaction is carried out at 55-65℃ for 3-5 hours to obtain an emulsion. After washing repeatedly with anhydrous ethanol, the precipitate is dried to obtain the modified acrylamide. The obtained modified acrylamide exhibits more wrinkles and protrusions on its surface morphology, forming more active sites, and demonstrating good water solubility and flocculation properties. The modified flocculant of this invention can not only compensate for the shortcomings of weak bridging ability caused by the low molecular weight of chitosan, but also improve the solubility of chitosan. Moreover, the addition of acrylamide gives the polymer higher chemical activity, enhancing its adsorption performance for heavy metal ions in the filtrate.

[0014] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0015] 1. This invention utilizes titanium dioxide waste acid to leach copper from iron-containing waste slag, and then uses a nano-precipitant to precipitate copper from the leachate. This process can leach out most of the copper, achieving a copper recovery rate of over 80%. Furthermore, during the treatment of iron-containing waste slag with titanium dioxide waste acid, most impurities such as sulfur and arsenic in the iron-containing waste slag are removed. The treated iron-containing waste slag mainly contains iron and can be used to prepare iron concentrate. This invention's process treats waste with waste, enabling resource recycling and bringing greater economic benefits to enterprises.

[0016] 2. This invention utilizes highly reactive nano-precipitants to remove heavy metal ions from the filtrate while reducing the loss of ferrous sulfate, enabling efficient recycling and reuse of ferrous sulfate. Subsequently, modified acrylamide with active groups is used as a flocculant, resulting in higher reactivity, good water solubility and flocculation properties, and enhanced adsorption performance for heavy metal ions. This allows for further treatment of titanium dioxide waste acid while recovering copper, thereby enabling the recycling and reuse of sulfuric acid as well. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0018] Example 1

[0019] 1. Preparation of nano-precipitants

[0020] Dissolve 50g of ammonium sulfate in 100ml of water, and gradually add NaCl at room temperature until saturation; dissolve 10g of sodium sulfide in 100ml of anhydrous ethanol, and gradually add NaCl at room temperature until saturation; then stir the two solutions thoroughly, filter under vacuum, wash the filter cake three times with anhydrous ethanol, and dry it under vacuum at 50℃ for 3 hours to obtain nanopowder materials.

[0021] 2. Preparation of modified flocculants

[0022] 10g of chitosan, 20g of nano-silica powder and 50g of acrylamide were fully dissolved in 1% acetic acid solution. Nitrogen was purged to remove oxygen, and cerium ammonium nitrate initiator was added under nitrogen atmosphere. The mixture was then reacted at 60℃ for 4 hours using reverse emulsion polymerization to obtain an emulsion. After washing 5 times with anhydrous ethanol, the precipitate was vacuum dried at 60℃ for 3 hours to obtain modified acrylamide.

[0023] 3. A copper beneficiation process for iron-containing waste slag, comprising the following steps:

[0024] S1. Add 20g of iron powder and 20g of ammonium fluoride to 1kg of titanium dioxide waste acid and react for a period of time to obtain a titanium dioxide waste acid pre-solution.

[0025] S2. Add 100g of iron-containing waste residue to 300mL of titanium dioxide waste acid pre-solution with sulfuric acid concentration of 123g / L. The reaction temperature is 30℃ and the reaction time is 3h. After the reaction is completed, filter the residue and wash it four times in countercurrent. Combine the leachate with the washing water, neutralize it with lime milk, and then perform solid-liquid separation.

[0026] S3. When the pH of the filtrate is adjusted to 4, 1.5 times the mass of the filtrate is added to precipitate copper with nano-precipitant. After reacting for 1 hour, 1.5 times the mass of the filtrate is added with modified flocculant. After filtration and washing, sulfuric acid is obtained.

[0027] Example 2

[0028] The difference between this embodiment and embodiment 1 is that the liquid-solid ratio of the titanium dioxide waste acid pre-solution to the iron-containing waste residue in S2 is 2:1.

[0029] Example 3

[0030] The difference between this embodiment and embodiment 1 is that in S2, the titanium dioxide waste acid pre-solution is diluted to a sulfuric acid mass concentration of 130 g / L.

[0031] Example 4

[0032] The difference between this embodiment and Embodiment 1 is that the amount of modified flocculant added in S3 is twice that of the filtrate.

[0033] Comparative Example 1

[0034] The difference between this comparative example and Example 1 is that it does not include step S1.

[0035] Comparative Example 2

[0036] The difference between this comparative example and Example 1 is that the nano-precipitant in step S3 is replaced with sodium sulfide.

[0037] Comparative Example 3

[0038] The difference between this comparative example and Example 1 is that the modified flocculant in step S3 is replaced with polyacrylamide.

[0039] Experimental Example 1

[0040] The mass fractions of the leaching products and recovered sulfuric acid from Examples 1-4 and Comparative Examples 1-3 were tested, and the results are shown in Table 1 below.

[0041] Table 1. Copper leaching rate and recovered sulfuric acid mass fraction from iron-containing waste residue.

[0042]

[0043]

[0044] As shown in Table 1, the use of the present invention to treat sulfuric acid residue with titanium dioxide waste acid can leach out most of the copper, with a copper recovery rate of over 80%. The copper mass fraction in the sulfide precipitate is greater than 40%, and sulfuric acid in the titanium dioxide waste acid can be recovered and reused at the same time, bringing greater economic benefits to enterprises.

[0045] Comparative Example 1 shows that the lack of reduction pretreatment of titanium dioxide waste acid resulted in a higher number of impurities in the waste acid, which reduced the leaching effect on copper and the quality of subsequent sulfuric acid recovery.

[0046] Comparative Example 2 shows that when the nano-precipitant was replaced with sodium sulfide, the copper recovery rate was only 23.66%, indicating a poor leaching effect on copper.

[0047] Comparative Example 3 shows that the flocculation effect of traditional flocculants is generally poor, while the modified acrylamide flocculant has a prominent flocculation effect, which can effectively enhance the adsorption performance of heavy metal ions in titanium dioxide waste acid and improve the recovery quality of sulfuric acid.

[0048] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A copper beneficiation process for iron-containing waste slag, characterized in that, Includes the following steps: S1. Add iron powder and ammonium fluoride to titanium dioxide waste acid and react for a period of time to obtain titanium dioxide waste acid pre-solution. S2. Add the iron-containing waste residue to the titanium dioxide waste acid pre-solution and control the reaction temperature at 20-50℃; S3. After the reaction is complete, adjust the pH of the solution to 3-4.5 and add the nano-precipitant. After reacting for a period of time, add the modified flocculant. After filtration and washing, precipitated copper is obtained. The nano-precipitant is a combination of soluble sulfate and sulfur. The soluble sulfate includes potassium sulfate or ammonium sulfate. The preparation method of the nano-precipitant is as follows: dissolve the soluble sulfate and sulfur separately in sodium chloride solution, then mix the two solutions, and after filtration, washing, and drying, nano-powder material is obtained. The modified flocculant is acrylamide grafted with hydroxyl or carboxyl groups; the preparation method of the modified polyacrylamide includes the following steps: a certain mass of chitosan, nano silica powder and acrylamide are fully dissolved in acetic acid solution, an initiator is added under a nitrogen atmosphere and heated; after reacting for a period of time by reverse emulsion polymerization, an emulsion is obtained, which is then washed and dried to obtain the modified acrylamide.

2. The copper beneficiation process for iron-containing waste slag according to claim 1, characterized in that, In S1, the amount of iron powder added is 1.5-2% of the mass of titanium dioxide waste acid, and the amount of ammonium fluoride added is 1.5-2% of the mass of titanium dioxide waste acid.

3. The copper beneficiation process for iron-containing waste slag according to claim 1, characterized in that, In S2, the titanium dioxide waste acid pre-solution is diluted to a sulfuric acid mass concentration of 120-130 g / L.

4. The copper beneficiation process for iron-containing waste slag according to claim 1, characterized in that, In S2, the liquid-to-solid ratio of the titanium dioxide waste acid pre-solution to the iron-containing waste residue is 1.5~4:1.

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