CN116143201A - Method for recycling copper and nickel from electroplating sludge - Google Patents

Abstract

The invention provides a method for recovering copper and nickel from electroplating sludge, which comprises the following steps: step 1: roasting the electroplating sludge at a low temperature to obtain roasting slag; the low-temperature roasting temperature is 350-450 ℃; step 2: adding biological acid into the roasting slag, stirring and pulping, and performing solid-liquid separation to obtain filtrate and filter residues; step 3: and adding a copper extractant and a nickel extractant into the filtrate, and respectively extracting to obtain cathode copper and nickel sulfate hexahydrate. The method provided by the invention has the characteristics of green and safe production process, low cost, obvious benefit, no wastewater discharge and the like, and in addition, the raw materials in the whole production process are cheap and convenient to purchase.

Description

Method for recycling copper and nickel from electroplating sludge

Technical Field

The invention relates to the technical field of treatment of electroplating sludge, in particular to a method for recycling copper and nickel from electroplating sludge.

Background

Electroplating is one of the three world pollution industries today. Electroplating wastewater is chemically treated to produce electroplating sludge with a large amount of heavy metals. The main components of the electroplating sludge are arranged into chromium, iron, copper, nickel, aluminum, zinc, magnesium, calcium, silicon, sulfur, cyanide and the like according to toxicity. Although the electroplating sludge contains a large amount of toxic and harmful heavy metals, the electroplating sludge is classified as dangerous waste by the name of China, a large amount of metal resources rich in the electroplating sludge can be recovered, such as nickel and copper with relatively high content, and the electroplating sludge has high recovery value.

In the existing electroplating sludge recycling treatment technology, when the electroplating sludge is leached by sulfuric acid directly, the following technical problems exist: the use of strong acid has higher requirements on production equipment, so that the production cost of the whole process chain is higher; the reaction process requires to control higher temperature, and the energy consumption is high; the leachate contains a large amount of impurity metals (especially iron), which complicates the subsequent separation and purification process of copper and nickel.

Disclosure of Invention

In order to solve the problems, the invention provides a method for recovering copper and nickel from electroplating sludge, which comprises the following steps:

step 1: roasting the electroplating sludge at a low temperature to obtain roasting slag; the low-temperature roasting temperature is 350-450 ℃;

step 2: adding biological acid into the roasting slag, stirring and pulping, and performing solid-liquid separation to obtain filtrate and filter residues;

step 3: and adding a copper extractant and a nickel extractant into the filtrate, and respectively extracting to obtain cathode copper and nickel sulfate hexahydrate.

Preferably, when the pH value is between 1.5 and 2.0 after biological acid is added into the roasting slag, a copper extractant and a nickel extractant are added into the filtrate, and cathode copper and nickel sulfate hexahydrate are obtained by extraction respectively; wherein the solid-to-liquid ratio of the roasting slag to the biological acid is 1:3.

Preferably, when the pH value is not stabilized to 1.5-2.0 after the biological acid is added into the roasting slag, the filtrate is returned to the microorganism culture tank for culture, and the filter residue is returned to the slurry tank.

Preferably, the biological acid is a biological acid cultured under the condition that thiobacillus thiooxidans takes sulfur as an energy substrate.

Preferably, a copper extractant and a special nickel extractant are added into the filtrate, and cathode copper and nickel sulfate hexahydrate are respectively obtained by extraction, comprising:

adding the copper extractant into the filtrate for extraction to obtain copper raffinate and a copper-containing organic phase;

adding a first stripping agent into the copper-containing organic phase for reaction to obtain copper stripping solution; electrolyzing the copper strip liquor to obtain the cathode copper;

after obtaining the copper raffinate and the copper-containing organic phase, it comprises:

adding the nickel extractant into the copper raffinate to extract to obtain nickel raffinate and a nickel-containing organic phase;

adding a second stripping agent into the nickel-containing organic phase to react to obtain nickel-rich liquid; and evaporating and crystallizing the obtained nickel-rich solution to obtain the nickel sulfate hexahydrate.

Preferably, the nickel containing organic phase is 1.3:1.0 compared to the nickel raffinate water, the copper extractant is Lix984DT100 diluent, the first stripping agent is sulfuric acid solution at a concentration of 180-200g/L, and the second stripping agent is sulfuric acid solution at a concentration of 75 g/L.

Preferably, the nickel extractant is obtained by adding sodium hydroxide solution into a special nickel extractant for HBL110 to carry out saponification treatment, and uniformly mixing the special nickel extractant for HBL110 and DT100 diluent after the saponification treatment according to a volume ratio of 1:1; wherein the saponification rate of the saponification treatment is controlled at 50%.

Preferably, after adding biological acid into the roasting slag to stir and slurry, and performing solid-liquid separation to obtain filtrate and filter residues, the method further comprises:

washing the filter residues by adopting clear water to obtain washing residues; wherein the solid-to-liquid ratio of the filter residue to the clear water is 1:4;

adding a nickel extractant into the copper raffinate to extract to obtain a nickel raffinate and a nickel-containing organic phase, and then, the method further comprises the following steps:

adding alkali into the nickel raffinate to perform neutralization precipitation to obtain precipitation slag;

mixing the precipitation slag, the washing slag and shale, and calcining to prepare shale ceramsite; wherein the washing slag contains impurity metals.

Preferably, the washing residue: the precipitated slag: the shale mass ratio is 3:2:5.

Compared with the prior art, the invention has the following advantages:

the invention provides a method for recovering copper and nickel from electroplating sludge, which comprises the following steps:

step 1: roasting the electroplating sludge at a low temperature to obtain roasting slag; the low-temperature roasting temperature is 350-450 ℃; step 2: adding biological acid into the roasting slag, stirring and pulping, and performing solid-liquid separation to obtain filtrate and filter residues; step 3: and adding a copper extractant and a nickel extractant into the filtrate, and respectively extracting to obtain cathode copper and nickel sulfate hexahydrate. The method provided by the invention has the characteristics of green and safe production process, low cost, obvious benefit, no wastewater discharge and the like, and in addition, the raw materials in the whole production process are cheap and convenient to purchase.

By adopting the method provided by the invention, firstly, the copper-nickel metal in the sulfurized state in the electroplating sludge is converted into the oxidized state through low-temperature roasting, other impurity metals can form compounds with spinel structures, and other organic matters in the electroplating sludge are consumed, so that the reduction is realized, and better recovery of copper and nickel is facilitated; then biological acid leaching is adopted, so that oxidized copper nickel metal can be dissolved in the biological acid to obtain filtrate, and a spinel-structured compound cannot be dissolved and is fixed in filter residues; and (3) respectively extracting and recycling copper and nickel metals in the obtained filtrate to obtain a high-purity copper and nickel product. According to the method provided by the invention, the copper and nickel in the electroplating sludge can be efficiently recovered and prepared into a high-purity product by no need of sulfuric acid and higher leaching temperature, other impurity metals are reduced from entering filtrate, the production flow of subsequent extraction is reduced, and the method has the characteristics of green and safe production process, low cost, obvious benefit, no wastewater discharge and the like. In addition, the raw materials in the whole production process are cheap and convenient to purchase.

Drawings

FIG. 1 is a flow chart of steps of a method for recovering copper and nickel from electroplating sludge according to an embodiment of the invention;

FIG. 2 is a process flow diagram of a method for recovering copper and nickel from electroplating sludge according to an embodiment of the invention.

Detailed Description

The invention will now be described in further detail with reference to the drawings and specific examples, which should not be construed as limiting the invention. The technical means used in the examples are conventional means well known to those skilled in the art unless otherwise indicated. Examples, methods, and apparatus employed in the present invention are those conventional in the art unless otherwise indicated.

The invention provides a method for recovering copper and nickel from electroplating sludge, and referring to FIG. 1, a step flow chart of the method for recovering copper and nickel from electroplating sludge is shown, and comprises the following steps:

s1, roasting electroplating sludge at a low temperature to obtain roasting slag; the low-temperature roasting temperature is 350-450 ℃;

s2, adding biological acid into the roasting slag, stirring and pulping, and performing solid-liquid separation to obtain filtrate and filter residues;

s3, adding a copper extractant and a nickel extractant into the filtrate, and respectively extracting to obtain cathode copper and nickel sulfate hexahydrate.

Wherein, the electroplating sludge adopts electroplating sludge with the water content of 60 percent, and the electroplating sludge contains 2.09 percent of nickel, 5.66 percent of copper, 0.31 percent of zinc and other metals.

In the embodiment of the invention, under the condition of sufficient air, roasting the electroplating sludge at low temperature to obtain roasting slag, adding biological acid into a slurry tank containing the roasting slag after the roasting is completed, stirring the slurry, and continuously feeding in the process. The overflow port is arranged on the slurry melting tank, and after the slurry melting is stirred for 1h, overflowed slurry is rapidly separated through the online filter to obtain filtrate and filter residues, at the moment, impurity metals are basically fixed in the filter residues, and the impurity metal content in the filtrate containing copper and nickel is extremely low, so that the influence on the recovery of subsequent copper and nickel metals after the impurity metals enter the filtrate is avoided. The filter residues are returned to the slurry melting tank according to the proportion, and the filtrate is returned to the microorganism culture tank for re-culture. After the pH value of the filtrate which is rapidly separated by the online filter is stabilized at 1.5-2.0, copper and nickel metals can be leached, filter residues enter a washing section and are used for preparing shale ceramisite, the filtrate enters a copper extraction section, at the moment, the filtrate contains nickel with the concentration of 6.83g/L, copper with the concentration of 18.66g/L and zinc with the concentration of 1.00g/L, and the content of other impurity metals is negligible compared with the content of copper and nickel. The raw material plating sludge contained 2.09% nickel and 5.66% copper in the filtrate, i.e., the filtrate contained nickel at a concentration of 6.83g/L and copper at a concentration of 18.66g/L, and the filtrate after removal of the impurity metals contained little zinc, and zinc was inexpensive and of no recovery value, so that zinc was not treated. Adding a copper extractant into the filtrate, extracting and electrolyzing to obtain an electrolytic copper product, adding a nickel extractant into a copper raffinate obtained after the copper extractant is added, and extracting and evaporating to crystallize to obtain a nickel sulfate product. By adopting the method provided by the invention, 99% of copper and nickel in the electroplating sludge are efficiently recovered and prepared into a high-purity product, other impurity metals are reduced from entering the leaching solution (filtrate), the production flow of subsequent extraction is reduced, and the method has the characteristics of green and safe production process, low cost, obvious benefit, low hazardous waste discharge and the like. In addition, the raw materials in the whole production process are cheap and convenient to purchase, and no wastewater is discharged.

Roasting the electroplating sludge at a low temperature for 30min to obtain roasting slag, wherein the mass is reduced by 20-30% in the process, and the mass is the mass burnt out after the electroplating sludge is oxidized, and particularly other organic matters are burnt out. The low-temperature roasting process is carried out under the condition of sufficient oxygen, copper-nickel metal in a vulcanized state is converted into an oxidized state through roasting, other impurity metals can form spinel-structure compounds, and other organic matters (flocculating agents) in electroplating sludge are consumed, so that the reduction is realized, and better recovery of copper-nickel is facilitated. The spinel structure-forming compounds are specifically: iron in the impurity metal is firstly sintered into an oxidation state, other impurity metals (calcium, aluminum and a small amount of copper and nickel) are sintered into the oxidation state, the iron in the oxidation state and the other impurity metals (calcium, aluminum and a small amount of copper and nickel) which are sintered into the oxidation state are reacted with each other to form a spinel-structured compound, and the compound with the crystal structure is insoluble in acid. After the low-temperature roasting is finished, the impurity metal is fixed in the filter residue, the impurity metal in the electroplating sludge is basically separated from copper and nickel, and at the moment, the copper and nickel can be leached out by adopting acid with low pH value. The roasting temperature is gradually increased, and the leaching rates of Ni and Cu are also gradually increased. If the roasting temperature is too low, other organic matters cannot be decomposed, and the reduction cannot be realized; if the roasting temperature exceeds 450 ℃, the copper nickel metal and the impurity metal cannot be separated, specifically: the copper-nickel oxide is also sintered into a crystal structure at too high a roasting temperature, so that copper-nickel of a subsequent crystal structure cannot be dissolved in biological acid, and further copper-nickel metal and impurity metal are fixed in filter residues after solid-liquid separation, so that the impurity metal is leached out together while copper-nickel is leached out, and the leaching rate of Ni and Cu is greatly reduced.

Preferably, when the pH value is between 1.5 and 2.0 after biological acid is added into the roasting slag, a copper extractant and a nickel extractant are added into the filtrate, and cathode copper and nickel sulfate hydrate are obtained by extraction respectively; wherein the solid-to-liquid ratio of the roasting slag to the biological acid is 1:3.

In specific implementation, the conditions of whether the filtrate can leach copper and nickel are as follows: the pH value is 1.5-2.0. The leaching conditions also indirectly define the amount of solids to liquid ratio. After the filtrate passes through an online filter, the pH value of the filtrate is stabilized to be 1.5-2.0, and the filtrate enters a copper extraction working section.

Preferably, when the pH value is not stabilized to 1.5-2.0 after the biological acid is added into the roasting slag, the filtrate is returned to the microorganism culture tank for culture, and the filter residue is returned to the slurry tank.

In specific implementation, the feeding and discharging of the microbial culture tank is kept in an on-line dynamic balance process, namely the speed of returning filtrate to the microbial culture tank for re-culturing and the speed of discharging biological acid are kept in balance all the time, the feeding and discharging speed is moderate, the biological acid regeneration efficiency needs to be met, namely the pH value of the filtrate fed back is ensured to be 2.0, and the pH value of the biological acid discharged is kept at 0.8 (the reduction of the pH value is realized by the regeneration effect of microorganisms).

The microbial culture tank material inlet and outlet keep on-line dynamic balance, and the leaching rate of copper and nickel is not changed substantially, but the recovery efficiency can be improved and the recovery time is greatly reduced from the process application. The pH value of the biological acid in the microbial culture tank is kept at 0.8, which is favorable for leading the biological acid regeneration system to reach the highest active point and leading the biological acid to grow rapidly. Since the microorganisms in the microorganism culture tank metabolize organic acids after feeding, a period of time is required for growth to bring the biological activity back to the highest point. The feeding and discharging of the microbial culture tank are always kept in on-line dynamic balance, even though the microbial culture tank is always feeding, due to moderate feeding and discharging speed and the regeneration effect of the biological acid, the pH value in the microbial culture tank after feeding can be quickly and always kept at 0.8, the growth environment of the microorganisms in the microbial culture tank is always at the highest active point, so that the microorganisms can quickly metabolize the biological acid, further more electroplating sludge can be treated, and the treatment time is greatly reduced.

In the concrete implementation, the feeding and discharging of the slurry melting tank is kept in an on-line dynamic balance process, namely, the biological acid evolves the slurry tank, filter residues return to the slurry melting tank, and the slurry after the biological acid is added and stirred for slurry melting is discharged out of the slurry melting tank. Because the feeding and discharging of the microorganism culture tank is kept in an on-line dynamic balance process, the feeding and discharging of the slurry tank are correspondingly kept in an on-line dynamic balance process.

When the method is concretely implemented, if the condition of copper extraction is not met (namely, the copper concentration is more than or equal to 5g/L and less than or equal to 15 g/L), biological regeneration can be carried out again, namely, slurry overflowed by repeated circulation is quickly separated through an online filter, filter residues are returned to a slurry dissolving tank according to proportion, filtrate is returned to a microorganism culture tank for re-culture, the step of roasting the newly fed electroplating sludge at low temperature is continued, biological acid is added for stirring and slurry dissolving, and the process enters a copper extraction section after the extraction condition is met. It should be noted that, the extraction conditions are only parameters, and the copper concentration increases with the number of repeated cycles.

Preferably, the biological acid is a biological acid cultured under the condition that thiobacillus thiooxidans takes sulfur as an energy substrate.

In the embodiment, the traditional wet leaching (directly leaching the electroplating sludge by sulfuric acid) is replaced by leaching the acid-producing capacity of the organism, so that the cost is saved, the defect that toxic gas is generated by directly using sulfuric acid leaching is avoided, and the method has the characteristics of safety, environment friendliness, reduction of hazardous waste emission and the like.

In particular, the biological acid with the pH value of 0.8 is cultured in a 9k culture medium with sulfur as an energy substrate at 35 ℃, because the biological activity of the biological acid is strongest in the environment with the pH value of 0.8 at 35 ℃. The lower the pH value of the biological acid is, the more favorable the leaching, but the lower the pH value is, the inhibition effect on the growth of the thalli is generated, the biological regeneration time is possibly prolonged, and the rate of feeding and discharging is further reduced.

Preferably, a copper extractant and a special nickel extractant are added into the filtrate, and cathode copper and nickel sulfate hexahydrate are respectively obtained by extraction, comprising:

adding the copper extractant into the filtrate for extraction to obtain copper raffinate and a copper-containing organic phase;

adding a first stripping agent into the copper-containing organic phase for reaction to obtain copper stripping solution;

electrolyzing the copper strip liquor to obtain the cathode copper;

after obtaining the copper raffinate and the copper-containing organic phase, it comprises:

adding the nickel extractant into the copper raffinate to extract to obtain nickel raffinate and a nickel-containing organic phase;

adding a second stripping agent into the nickel-containing organic phase to react to obtain nickel-rich liquid; and evaporating and crystallizing the obtained nickel-rich solution to obtain the nickel sulfate hexahydrate.

In the concrete implementation, the temperature is controlled at room temperature in the whole copper extraction process, and the temperature in the whole nickel extraction process is controlled at about 30 ℃. Wherein, the purity of the obtained cathode copper is high-purity copper with 99.999 percent, the concentration of nickel in the obtained nickel-rich liquid is 35.25g/L, the concentration of zinc is 0.063g/L, and the concentration of nickel in the nickel raffinate is lower than 0.1g/L.

Preferably, the nickel containing organic phase is 1.3:1.0 compared to the nickel raffinate water, the copper extractant is Lix984, DT100 diluent, the first stripping agent is sulfuric acid solution at a concentration of 180-200g/L, and the second stripping agent is sulfuric acid solution at a concentration of 75 g/L.

Preferably, the nickel extractant is obtained by adding sodium hydroxide solution into a special nickel extractant for HBL110 to carry out saponification treatment, and uniformly mixing the special nickel extractant for HBL110 and DT100 diluent after the saponification treatment according to a volume ratio of 1:1; wherein the saponification rate of the saponification treatment is controlled at 50%.

In the specific implementation, the mass concentration of the sodium hydroxide solution is 30%. The special nickel extractant can only play a role under alkaline condition, after the sodium hydroxide solution is added, hydrogen in the special nickel extractant is replaced by sodium, and then sodium in the special nickel extractant is exchanged with nickel during extraction, nickel metal is extracted from the solution, and a nickel-containing organic phase is obtained.

Preferably, after adding biological acid into the roasting slag to stir and slurry, and performing solid-liquid separation to obtain filtrate and filter residues, the method further comprises:

washing the filter residues by adopting clear water to obtain washing residues; wherein the solid-to-liquid ratio of the filter residue to the clear water is 1:4;

adding a nickel extractant into the copper raffinate to extract to obtain a nickel raffinate and a nickel-containing organic phase, and then, the method further comprises the following steps:

adding alkali into the nickel raffinate to perform neutralization precipitation to obtain precipitation slag;

mixing the precipitation slag, the washing slag and shale, and calcining to prepare shale ceramsite; wherein the washing slag contains impurity metals.

Wherein, the sediment slag comprises: toxic impurity metals, including in the precipitation slag: the mixture of some oxides and sulfate components such as aluminum hydroxide, calcium hydroxide or calcium sulfate is general solid waste which is nontoxic and harmless.

In specific implementation, the filter residues are countercurrent washed for 4 times according to the solid-to-liquid ratio of 1:4 to obtain washing residues, the washed washing water can be returned to a microorganism culture tank for culture, the precipitation residues, the washing residues and the shale are mixed and then can be stirred, the stirring time is 1h, and the whole process of granulation and calcination is as follows: firstly, drying at 105 ℃ for 2 hours, roasting at 550 ℃ for 30 minutes, and finally, roasting at 1150 ℃ for 10 minutes, and glazing to prepare shale ceramsite, wherein no solid waste is generated in the whole process. In order to recycle solid waste, the nickel raffinate is used for neutralizing precipitation slag and leaching slag (washing slag) to be mixed with shale, and the shale ceramsite is prepared by detoxification, so that the generation of solid waste is reduced, and the performance of the shale ceramsite is maximized by combining a calcination means.

Preferably, the washing residue: the precipitated slag: the shale mass ratio is 3:2:5.

In order that those skilled in the art will better understand the present invention, a method provided by the present invention will be described below with reference to a number of specific examples.

Example 1

The electroplating sludge used in this example was produced by using a water content of 60% from a plant in Zhejiang as a raw material, and contained 2.09% of nickel, 5.66% of copper, and 0.31% of metals such as zinc.

Referring to fig. 2, a process flow diagram of a method for recovering copper and nickel from electroplating sludge is shown in accordance with an embodiment of the present invention. The process flow is as follows: roasting electroplating sludge at 400 ℃ in an air atmosphere to obtain roasting slag, adding biological acid for pulping treatment, and stirring, wherein the biological acid is a biological acid with pH of 0.8 cultured by thiobacillus thiooxidans at 35 ℃ in a 9k culture medium and sulfur as an energy substrate. The pH value of the slurry is controlled between 1.5 and 2.0 according to the solid-to-liquid ratio of 1:3, the stirring time is 1h, after the slurry is completely dissolved, the slurry overflows into an online filter for filtering, and filtrate and filter residues are obtained, wherein the filtrate contains nickel with the concentration of 6.83g/L, copper with the concentration of 18.66g/L and zinc with the concentration of 1.00 g/L. And returning the filtrate to the microorganism culture tank for culture under the condition that the pH value of the filtrate passing through the online filter is not stabilized at 1.5-2.0, and returning filter residues to the slurry dissolving tank.

After the pH value of the filtrate is stabilized between 1.5 and 2.0, the filtrate enters a copper extraction working section, lix984 is added into the filtrate, DT100 extractant is added for extraction, and then copper stripping liquid is obtained after stripping, wherein the stripping agent is sulfuric acid solution with the concentration of 180g/L, the copper stripping liquid enters an electrolysis system to prepare cathode copper, the cathode copper is directly packaged into bags for sale, and the electrolyte is recycled as the stripping agent. The copper raffinate enters a nickel extraction process section, a nickel extractant is added into the copper raffinate, and the nickel raffinate is extracted through 18 extraction lines of 5-level extraction, 5-level washing, 4-level back extraction and 3-level back washing to obtain the nickel raffinate, pure water is adopted as washing water, the washed water returns to a washing water storage tank for recycling, and the ratio of organic phase to aqueous phase is 1.3/1.0; and back extraction is carried out to obtain nickel-rich liquid, the back extractant is sulfuric acid solution with the concentration of 75g/L, the nickel concentration in the nickel-rich liquid is 35.25g/L, the zinc concentration is 0.063g/L, and the nickel-rich liquid enters an evaporative crystallization system to prepare a nickel sulfate hexahydrate product. The whole copper-nickel extraction process is carried out in a multi-stage mixer-settler, the copper extraction temperature is controlled to be about 30 ℃, and the nickel extraction temperature is controlled to be about 30 ℃. The nickel extractant is obtained by adding a proper amount of sodium hydroxide solution with the mass concentration of 30% into a special nickel extractant HBL110 to carry out 1-level saponification treatment, controlling the saponification rate at 50%, and uniformly mixing with DT100 diluent according to the volume ratio of 1:1.

And (3) performing slurry washing on filter residues and clear water according to a solid-to-liquid ratio of 1:4, and performing plate and frame filter pressing on the slurry to obtain washing water and washing residues, wherein the washing water is recycled into the microorganism culture tank. Adding a proper amount of alkali and water in a microorganism culture tank into nickel raffinate with the concentration of nickel being lower than 0.1g/L to perform neutralization precipitation to obtain precipitation slag, and mixing the precipitation slag and washing slag into shale to prepare shale ceramsite.

When roasting is carried out at the roasting temperature of 400 ℃, the leaching rate of Ni and Cu in roasting slag almost reaches 100%, 99% efficient recovery of copper and nickel in electroplating sludge is realized, high-value products are prepared, other impurity metals are reduced from entering leaching liquid, and the production flow of subsequent extraction is reduced; the leaching residues are detoxified, and the production of solid wastes is reduced by preparing shale ceramisites. The raw materials and the auxiliary materials in the production process are cheap and convenient to purchase, the cost is low, the income is obvious, and the emission of hazardous wastes is low.

Comparative example 1

The only difference from the starting materials, process flows and conditions of example 1 is that: the front end is roasted at a roasting temperature of 500 ℃.

The leaching rates of Ni and Cu in the final electroplating sludge roasting slag are 43.55 percent and 57.68 percent respectively. Therefore, the leaching rate of Ni and Cu is greatly reduced by adopting higher roasting temperature.

Example 2

The plating sludge used in this example was prepared from a plating sludge containing 1.38% of nickel, 1.65% of copper, and 1.90% of metals such as zinc, which was discharged from a plating park in the middle mountain of Guangdong, and had a water content of 69.14%.

Roasting electroplating sludge at 400 ℃ in an air atmosphere to obtain roasting slag, adding biological acid for pulping treatment, and stirring, wherein the biological acid is a biological acid with pH of 0.8 cultured by thiobacillus thiooxidans at 35 ℃ in a 9k culture medium and sulfur as an energy substrate. The pH value of the slurry is controlled between 1.5 and 2.0 according to the solid-to-liquid ratio of 1:3, the stirring time is 1h, after the slurry is completely dissolved, the slurry overflows into an online filter for filtering, and filtrate and filter residues are obtained, wherein the filtrate contains nickel with the concentration of 6.13g/L, copper with the concentration of 7.06g/L and zinc with the concentration of 8.75 g/L. And returning the filtrate to the microorganism culture tank for culture under the condition that the pH value of the filtrate passing through the online filter is not stabilized at 1.5-2.0, and returning filter residues to the slurry dissolving tank.

After the pH value of the filtrate is stabilized between 1.5 and 2.0, the filtrate enters a copper extraction working section, lix984 is added into the filtrate, DT100 extractant is added for extraction, and then copper stripping liquid is obtained after stripping, wherein the stripping agent is sulfuric acid solution with the concentration of 180g/L, the copper stripping liquid enters an electrolysis system to prepare cathode copper, the cathode copper is directly packaged into bags for sale, and the electrolyte is recycled as the stripping agent. The copper raffinate enters a nickel extraction process section, a nickel extractant is added into the copper raffinate, and the nickel raffinate is extracted through 18 extraction lines of 5-level extraction, 5-level washing, 4-level back extraction and 3-level back washing to obtain the nickel raffinate, pure water is adopted as washing water, the washed water returns to a washing water storage tank for recycling, and the ratio of organic phase to aqueous phase is 1.3/1.0; and back extraction is carried out to obtain nickel-rich liquid, the back extractant is sulfuric acid solution with the concentration of 75g/L, the nickel concentration in the nickel-rich liquid is 40.64g/L, the zinc concentration is 0.47g/L, and the nickel-rich liquid enters an evaporation crystallization system to prepare a nickel sulfate hexahydrate product. The whole copper-nickel extraction process is carried out in a multi-stage mixer-settler, the copper extraction temperature is controlled to be about 30 ℃, and the nickel extraction temperature is controlled to be about 30 ℃. The nickel extractant is obtained by adding a proper amount of sodium hydroxide solution with the mass concentration of 30% into a special nickel extractant HBL110 to carry out 1-level saponification treatment, controlling the saponification rate at 50%, and uniformly mixing with DT100 diluent according to the volume ratio of 1:1.

And (3) performing slurry washing on filter residues and clear water according to a solid-to-liquid ratio of 1:4, and performing plate and frame filter pressing on the slurry to obtain washing water and washing residues, wherein the washing water is recycled into the microorganism culture tank. Adding a proper amount of alkali and water in a microorganism culture tank into nickel raffinate with the concentration of nickel being lower than 0.1g/L to perform neutralization precipitation to obtain precipitation slag, and mixing the precipitation slag and washing slag into shale to prepare shale ceramsite.

When the roasting temperature of 400 ℃ is adopted for roasting, the leaching rate of Ni and Cu in the roasting slag almost reaches 100%, the 99% efficient recovery of copper and nickel in the electroplating sludge is realized, and the high-value product is prepared.

Comparative example 2

The only difference from the starting materials, process flows and conditions of example 2 is that: the front end is roasted at a roasting temperature of 500 ℃.

The leaching rates of Ni and Cu in the final electroplating sludge roasting slag are 61.12% and 72.64%, respectively. Therefore, the leaching rate of Ni and Cu is greatly reduced by adopting higher roasting temperature.

Example 3

The plating sludge used in this example was prepared from a plating sludge having a water content of 65.94% and containing metals such as nickel 4.92%, copper 4.64% and zinc 2.17% in Tianjin.

Roasting electroplating sludge at 400 ℃ in an air atmosphere to obtain roasting slag, adding biological acid for pulping treatment, and stirring, wherein the biological acid is a biological acid with pH of 0.8 cultured by thiobacillus thiooxidans at 35 ℃ in a 9k culture medium and sulfur as an energy substrate. The pH value of the slurry is controlled between 1.5 and 2.0 according to the solid-to-liquid ratio of 1:3, the stirring time is 1h, after the slurry is completely dissolved, the slurry overflows into an online filter for filtering, and filtrate and filter residues are obtained, wherein the filtrate contains nickel with the concentration of 23.19g/L, copper with the concentration of 21.87g/L and zinc with the concentration of 10.23 g/L. And returning the filtrate to the microorganism culture tank for culture under the condition that the pH value of the filtrate passing through the online filter is not stabilized at 1.5-2.0, and returning filter residues to the slurry dissolving tank.

After the pH value of the filtrate is stabilized between 1.5 and 2.0, the filtrate enters a copper extraction working section, lix984 is added into the filtrate, DT100 extractant is added for extraction, and then copper stripping liquid is obtained after stripping, wherein the stripping agent is sulfuric acid solution with the concentration of 180g/L, the copper stripping liquid enters an electrolysis system to prepare cathode copper, the cathode copper is directly packaged into bags for sale, and the electrolyte is recycled as the stripping agent. The copper raffinate enters a nickel extraction process section, a nickel extractant is added into the copper raffinate, and the nickel raffinate is extracted through 18 extraction lines of 5-level extraction, 5-level washing, 4-level back extraction and 3-level back washing to obtain the nickel raffinate, pure water is adopted as washing water, the washed water returns to a washing water storage tank for recycling, and the ratio of organic phase to aqueous phase is 1.3/1.0; and carrying out back extraction to obtain nickel-rich liquid, wherein the back extractant is sulfuric acid solution with the concentration of 75g/L, the concentration of nickel in the nickel-rich liquid is 39.86g/L, the concentration of zinc in the nickel-rich liquid is 0.43g/L, and the nickel-rich liquid enters an evaporation crystallization system to prepare a nickel sulfate hexahydrate product. The whole copper-nickel extraction process is carried out in a multi-stage mixer-settler, the copper extraction temperature is controlled to be about 30 ℃, and the nickel extraction temperature is controlled to be about 30 ℃. The nickel extractant is obtained by adding a proper amount of sodium hydroxide solution with the mass concentration of 30% into a special nickel extractant HBL110 to carry out 1-level saponification treatment, controlling the saponification rate at 50%, and uniformly mixing with DT100 diluent according to the volume ratio of 1:1.

And (3) performing slurry washing on filter residues and clear water according to a solid-to-liquid ratio of 1:4, and performing plate and frame filter pressing on the slurry to obtain washing water and washing residues, wherein the washing water is recycled into the microorganism culture tank. Adding a proper amount of alkali and water in a microorganism culture tank into nickel raffinate with the concentration of nickel being lower than 0.1g/L to perform neutralization precipitation to obtain precipitation slag, and mixing the precipitation slag and washing slag into shale to prepare shale ceramsite.

When the roasting temperature of 400 ℃ is adopted for roasting, the leaching rate of Ni and Cu in the roasting slag almost reaches 100%, the 99% efficient recovery of copper and nickel in the electroplating sludge is realized, and the high-value product is prepared.

Comparative example 3

The only difference from the starting materials, process flows and conditions of example 3 is that: the front end is roasted at a roasting temperature of 500 ℃.

The leaching rates of Ni and Cu in the final electroplating sludge roasting slag are 16.90% and 49.24%, respectively. Therefore, the leaching rate of Ni and Cu is greatly reduced by adopting higher roasting temperature.

For the purposes of simplicity of explanation, the methodologies are shown as a series of acts, but one of ordinary skill in the art will recognize that the present invention is not limited by the order of acts described, as some acts may, in accordance with the present invention, occur in other orders and concurrently. Further, those skilled in the art will recognize that the embodiments described in the specification are all of the preferred embodiments, and that the acts and components referred to are not necessarily required by the present invention.

The above description of the method for recovering copper and nickel from electroplating sludge provided by the invention has been presented in detail, and specific examples are applied herein to illustrate the principles and embodiments of the invention, the above examples are only for helping to understand the method and core ideas of the invention; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present invention, the present description should not be construed as limiting the present invention in view of the above.

Claims (9)

1. A method for recovering copper and nickel from electroplating sludge, the method comprising the steps of:

step 1: roasting the electroplating sludge at a low temperature to obtain roasting slag; the low-temperature roasting temperature is 350-450 ℃;

step 2: adding biological acid into the roasting slag, stirring and pulping, and performing solid-liquid separation to obtain filtrate and filter residues;

step 3: and adding a copper extractant and a nickel extractant into the filtrate, and respectively extracting to obtain cathode copper and nickel sulfate hexahydrate.

2. The method according to claim 1, wherein after the biological acid is added into the roasting slag, when the pH value is between 1.5 and 2.0, a copper extractant and a nickel extractant are added into the filtrate, and cathode copper and nickel sulfate hydrate are obtained by extraction respectively; wherein the solid-to-liquid ratio of the roasting slag to the biological acid is 1:3.

3. The method according to claim 1, wherein the filtrate is returned to the microorganism culture tank for culture and the residue is returned to the slurrying tank in the case where the pH is not stabilized at 1.5 to 2.0 after the addition of the biological acid to the roasting residue.

4. The method according to claim 1, wherein the biological acid is a biological acid cultured under the condition that thiobacillus thiooxidans uses sulfur as an energy substrate.

5. The method according to claim 1, wherein adding a copper extractant and a special nickel extractant to the filtrate, respectively extracting to obtain cathode copper and nickel sulfate hexahydrate, comprises:

adding the copper extractant into the filtrate for extraction to obtain copper raffinate and a copper-containing organic phase;

adding a first stripping agent into the copper-containing organic phase for reaction to obtain copper stripping solution;

electrolyzing the copper strip liquor to obtain the cathode copper;

after obtaining the copper raffinate and the copper-containing organic phase, it comprises:

adding the nickel extractant into the copper raffinate to extract to obtain nickel raffinate and a nickel-containing organic phase;

adding a second stripping agent into the nickel-containing organic phase to react to obtain nickel-rich liquid; and evaporating and crystallizing the obtained nickel-rich solution to obtain the nickel sulfate hexahydrate.

6. The process of claim 5, wherein the nickel containing organic phase is 1.3:1.0 compared to the nickel raffinate water, the copper extractant is Lix984 and DT100 diluent, the first stripping agent is a sulfuric acid solution having a concentration of 180-200g/L, and the second stripping agent is a sulfuric acid solution having a concentration of 75 g/L.

7. The method according to claim 5, wherein the nickel extractant is obtained by adding sodium hydroxide solution into a special nickel extractant for HBL110 to carry out saponification treatment, and uniformly mixing the special nickel extractant for HBL110 and DT100 diluent after the saponification treatment according to a volume ratio of 1:1; wherein the saponification rate of the saponification treatment is controlled at 50%.

8. The method according to claim 1 or 5, wherein after adding a biological acid to the roasting slag and stirring to slurry, performing solid-liquid separation to obtain filtrate and filter residue, the method further comprises:

washing the filter residues by adopting clear water to obtain washing residues; wherein the solid-to-liquid ratio of the filter residue to the clear water is 1:4;

adding a nickel extractant into the copper raffinate to extract to obtain a nickel raffinate and a nickel-containing organic phase, and then, the method further comprises the following steps:

adding alkali into the nickel raffinate to perform neutralization precipitation to obtain precipitation slag;

mixing the precipitation slag, the washing slag and shale, and calcining to prepare shale ceramsite; wherein the washing slag contains impurity metals.

9. The method of claim 8, wherein the wash slag: the precipitated slag: the shale mass ratio is 3:2:5.

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