CN114309635A - Method for preparing superfine silver powder by using waste photosensitive film - Google Patents
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- CN114309635A CN114309635A CN202111575690.XA CN202111575690A CN114309635A CN 114309635 A CN114309635 A CN 114309635A CN 202111575690 A CN202111575690 A CN 202111575690A CN 114309635 A CN114309635 A CN 114309635A
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- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 title claims abstract description 145
- 238000000034 method Methods 0.000 title claims abstract description 54
- 239000002699 waste material Substances 0.000 title claims abstract description 44
- 239000000243 solution Substances 0.000 claims abstract description 87
- 229910052709 silver Inorganic materials 0.000 claims abstract description 68
- 239000004332 silver Substances 0.000 claims abstract description 68
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims abstract description 54
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 33
- 239000002245 particle Substances 0.000 claims abstract description 29
- 239000000839 emulsion Substances 0.000 claims abstract description 26
- 239000011268 mixed slurry Substances 0.000 claims abstract description 23
- 230000010355 oscillation Effects 0.000 claims abstract description 20
- 238000001914 filtration Methods 0.000 claims abstract description 19
- 239000007864 aqueous solution Substances 0.000 claims abstract description 15
- 238000010438 heat treatment Methods 0.000 claims abstract description 12
- 238000005406 washing Methods 0.000 claims abstract description 12
- 238000003756 stirring Methods 0.000 claims abstract description 11
- 239000002985 plastic film Substances 0.000 claims abstract description 10
- 229920006255 plastic film Polymers 0.000 claims abstract description 10
- 238000001035 drying Methods 0.000 claims abstract description 8
- 239000008394 flocculating agent Substances 0.000 claims abstract description 7
- 238000001816 cooling Methods 0.000 claims abstract description 6
- 230000003301 hydrolyzing effect Effects 0.000 claims abstract description 6
- 239000002244 precipitate Substances 0.000 claims abstract description 4
- 229920002401 polyacrylamide Polymers 0.000 claims description 18
- 125000002091 cationic group Chemical group 0.000 claims description 11
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 10
- 239000012295 chemical reaction liquid Substances 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 3
- 230000008569 process Effects 0.000 abstract description 12
- 238000002360 preparation method Methods 0.000 abstract description 6
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- 238000004062 sedimentation Methods 0.000 description 10
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 9
- 238000005054 agglomeration Methods 0.000 description 9
- 230000002776 aggregation Effects 0.000 description 9
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- 230000007062 hydrolysis Effects 0.000 description 8
- 238000006460 hydrolysis reaction Methods 0.000 description 8
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- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- 239000004033 plastic Substances 0.000 description 6
- 239000012065 filter cake Substances 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 238000004140 cleaning Methods 0.000 description 4
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- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- 229910021607 Silver chloride Inorganic materials 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 description 2
- 239000003638 chemical reducing agent Substances 0.000 description 2
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- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 229910000510 noble metal Inorganic materials 0.000 description 2
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- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- 241000894006 Bacteria Species 0.000 description 1
- 108010010803 Gelatin Proteins 0.000 description 1
- WHNWPMSKXPGLAX-UHFFFAOYSA-N N-Vinyl-2-pyrrolidone Chemical compound C=CN1CCCC1=O WHNWPMSKXPGLAX-UHFFFAOYSA-N 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- 230000000844 anti-bacterial effect Effects 0.000 description 1
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- 229960005070 ascorbic acid Drugs 0.000 description 1
- 235000010323 ascorbic acid Nutrition 0.000 description 1
- 239000011668 ascorbic acid Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 239000004327 boric acid Substances 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
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- 239000000843 powder Substances 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
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- -1 silver ions Chemical class 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- GGCZERPQGJTIQP-UHFFFAOYSA-N sodium;9,10-dioxoanthracene-2-sulfonic acid Chemical compound [Na+].C1=CC=C2C(=O)C3=CC(S(=O)(=O)O)=CC=C3C(=O)C2=C1 GGCZERPQGJTIQP-UHFFFAOYSA-N 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 229910001868 water Inorganic materials 0.000 description 1
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- Silver Salt Photography Or Processing Solution Therefor (AREA)
Abstract
The invention provides a method for preparing superfine silver powder by using waste photosensitive films, which comprises the steps of adding the waste photosensitive films into a sodium hydroxide solution for ultrasonic oscillation treatment to obtain a silver removing solution and a plastic film base; adjusting the pH value of the silver removing solution, adding a flocculating agent, stirring, and separating to obtain mixed slurry containing silver powder and an emulsion; adding the mixed slurry into a glycerol aqueous solution at normal temperature, gradually heating and stirring until the temperature reaches a first temperature; preserving heat under the condition of a first temperature to dissolve the mixed slurry into the glycerol aqueous solution and form a uniform solution; heating to a second temperature, preserving heat, hydrolyzing under the ultrasonic oscillation condition until silver particles are settled, cooling to a third temperature, and filtering and separating precipitates to obtain primary crude silver powder; and purifying, washing, filtering and drying the primary coarse silver powder to obtain the superfine silver powder. The method designed by the invention has the advantages of simple process, low cost and controllable quality, is suitable for large-scale industrial production, and can solve the problem that the existing superfine silver powder preparation process is not suitable for large-scale production.
Description
Technical Field
The invention belongs to the field of silver-containing solid waste resource utilization, relates to a silver recovery technology in silver-containing waste films, and particularly relates to a method for preparing superfine silver powder by using waste photosensitive films.
Background
The superfine silver powder is noble metal powder, has the advantages of large specific surface area, high activity, good conductivity, good antibacterial performance and the like, and is generally applied to catalyst materials, antistatic materials, low-temperature superconducting materials, electronic slurry, biosensor materials and functional materials for resisting bacteria, deodorizing and absorbing ultraviolet rays. At present, the preparation method of the superfine silver powder comprises a physical method and a chemical method, the physical method for preparing the superfine silver powder has the problems of complex process and poor performance of the superfine silver powder, and the chemical method has the defects of harsh reaction conditions, complex equipment and process and the like, and is difficult to be applied to the industrial production of the superfine silver powder on a large scale.
The industrial small-batch preparation of the superfine silver powder takes high-purity soluble silver salt as a raw material and is prepared by a liquid-phase chemical reduction method, but the method has the problems of single raw material source, high cost, easy agglomeration of silver ions in the reaction process, high process complexity, difficult control of product quality, unsuitability for large-scale production and the like.
In the fields of integrated circuit boards, medical fields and industrial flaw detection, used photosensitive films are treated as dangerous waste products and contain noble metal silver, so that at present, methods for preparing superfine silver powder by using waste photosensitive films are available, for example, a chemical burning method, a chemical dissolving and precipitating method and the like are adopted to recover simple substance silver blocks, and the simple substance silver blocks are prepared into the superfine silver powder.
For example: the Chinese published patent CN107974564A provides a method for preparing superfine silver powder by using waste photographic films, which uses nitric acid to leach silver paste in the waste photographic films; then converting silver particles in the silver paste into silver chloride by using sodium chloride, sodium hydroxide, aluminum chloride, a flocculating agent and the like; then, adding sodium carbonate and boric acid into silver chloride at high temperature to be smelted into high-purity silver; finally, the high-purity silver reacts with nitric acid, water, ammonia water, PVP, ascorbic acid and the like to generate the superfine silver powder. The method combines the silver recovery on the waste film with the liquid phase chemical reduction method to prepare the superfine silver powder, and has the problems of longer preparation flow, complex process, adoption of high-concentration strong acid and strong base substances in the preparation process, no environmental friendliness and high environmental protection pressure.
For another example: chinese published patent CN113528851A provides a method for recovering silver from silver-containing waste films, which comprises eluting silver on the waste films with alkali solution, adjusting PH with acid to separate silver mud by natural sedimentation, treating the silver mud with high-temperature steam to obtain coarse silver particles, and finally making the coarse silver particles into standard silver ingots by metallurgy. The method has the problems of high reaction temperature of high-temperature water vapor hydrolysis of silver, limited contact surface between the high-temperature water vapor and the surface of the silver mud, long reaction time, gas generated by reaction needing to be treated by a gas device, high treatment cost, high equipment cost and the like.
Disclosure of Invention
The invention aims to provide a method for preparing superfine silver powder by using waste photosensitive films, which directly prepares the superfine silver powder by using the waste photosensitive films.
The technical scheme for realizing the purpose of the invention is as follows: a method for preparing superfine silver powder by using waste photosensitive films comprises the following steps:
s1, adding the waste photosensitive film into a sodium hydroxide solution for ultrasonic oscillation treatment, and filtering to obtain a silver-removing solution and a plastic film base;
s2, adjusting the pH value of the silver removing solution to 2-5 by using a sulfuric acid solution, adding a flocculating agent PAM, stirring, standing, and separating to obtain a mixed slurry containing silver powder and an emulsion;
s3, adding the mixed slurry into glycerol aqueous solution at normal temperature, gradually heating and stirring until the temperature reaches a first temperature;
s4, preserving heat under the first temperature condition to enable the mixed slurry to be dissolved into the glycerol aqueous solution and form a uniform solution;
s5, heating the uniform solution to a second temperature, preserving heat, and hydrolyzing the emulsion under the ultrasonic oscillation condition until silver particles are settled in the uniform solution;
s6, cooling the reaction liquid to a third temperature in the step S5, and filtering and separating precipitates to obtain first-grade crude silver powder;
and S7, purifying, washing, filtering and drying the primary coarse silver powder to obtain the superfine silver powder.
The method for preparing the superfine silver powder by using the waste photosensitive film is characterized in that in the processes from the step S3 to the step S6, the emulsion in the mixed slurry is hydrolyzed, the hydrolysis degree of the emulsion is controlled to ensure the sedimentation of the primary coarse silver powder, and the action principle is as follows: through the control of factors such as the first temperature, the second temperature, the third temperature, the ultrasonic oscillation and the like, when the silver particle sedimentation phenomenon occurs, the emulsion in the mixed slurry is partially hydrolyzed to avoid excessive hydrolysis of the emulsion, and when the silver particle sedimentation phenomenon occurs, the residual emulsion can play a role of a surfactant, so that the sedimentary silver particles are dispersed to avoid agglomeration, and the purity of the primary coarse silver powder is further ensured.
In an embodiment of the present invention, in the step S3, the mass fraction of the glycerol in the glycerol aqueous solution is 5 to 10%.
In an embodiment of the invention, in the step S2, the flocculant PAM is a cationic polyacrylamide solution, the concentration of the cationic polyacrylamide solution is 0.1% to 0.2%, and the addition amount of the cationic polyacrylamide solution is 0.5% to 1% of the mass of the silver removing solution.
In one embodiment of the present invention, in the method for preparing the ultrafine silver powder using the waste photosensitive film, the plastic film base separated in step S1 is further subjected to a washing process, and the separated washing solution is combined with the desilvering solution. Further, the liquid for washing the plastic substrate in the above step is preferably deionized water.
In an embodiment of the present invention, in step S5, the uniform solution is hydrolyzed by using intermittent ultrasonic oscillation.
In another embodiment of the present invention, in step S1, the waste photosensitive film is subjected to ultrasonic vibration at 30-50 ℃.
In another embodiment of the present invention, the first temperature is 50 to 70 ℃, the second temperature is 80 to 120 ℃, and the third temperature is 70 to 90 ℃. Further, the first temperature is preferably 60 +/-5 ℃, the second temperature is preferably 100-110 ℃, and the third temperature is preferably 80 +/-5 ℃.
Compared with the prior art, the invention has the beneficial effects that: the method for preparing the superfine silver powder provided by the invention utilizes the characteristic that simple substance silver in the waste photosensitive film is uniformly dispersed in an emulsion layer, abandons a chemical dissolution precipitation method and a high-temperature smelting method which are commonly adopted in a silver recovery process in the traditional film, and only adopts the special process design from step S3 to step S6 to collect and purify silver particles, thereby obtaining the superfine silver powder. The method for preparing the superfine silver powder has the advantages of simple process flow, low cost and controllable product quality, is suitable for large-scale industrial production, and can solve the problem that the existing superfine silver powder preparation process is not suitable for large-scale production.
Drawings
In order to more clearly illustrate the technical solution of the embodiment of the present invention, the drawings used in the description of the embodiment will be briefly introduced below. It should be apparent that the drawings in the following description are only for illustrating the embodiments of the present invention or technical solutions in the prior art more clearly, and that other drawings can be obtained by those skilled in the art without any inventive work.
FIG. 1 is a flow chart of a method for preparing ultrafine silver powder using a waste photosensitive film according to an embodiment;
fig. 2 is a flowchart illustrating another method for preparing ultrafine silver powder using a waste photosensitive film according to an embodiment.
Detailed Description
The invention will be further described with reference to specific embodiments, and the advantages and features of the invention will become apparent as the description proceeds. These examples are illustrative only and do not limit the scope of the present invention in any way. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention, and that such changes and modifications may be made without departing from the spirit and scope of the invention.
In the description of the present embodiments, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit to a number of indicated technical features. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the invention, the meaning of "a plurality" is two or more unless otherwise specified.
The specific embodiment discloses a method for preparing superfine silver powder by using waste photosensitive films, which comprises the following steps as shown in figure 1:
and S1, adding the waste photosensitive film into a sodium hydroxide solution for ultrasonic oscillation treatment, and filtering to obtain a silver-removing solution and a plastic film base.
In the step, in order to improve the effect of the sodium hydroxide solution on the waste photosensitive film, the silver grains in the plastic film base are fully separated and enter the silver removing solution, and before the sodium hydroxide solution is treated, the waste photosensitive film is preferably crushed.
Meanwhile, in order to improve the stripping efficiency of the silver particles from the sodium hydroxide solution, ultrasonic oscillation treatment is carried out on the waste photosensitive film under the conditions of 30-50 ℃ and 3-5% of the sodium hydroxide solution.
And S2, adjusting the pH value of the silver removing solution to 2-5 by using a sulfuric acid solution, adding a flocculating agent PAM, stirring, standing, and separating to obtain a mixed slurry containing silver powder and an emulsion.
In the step, silver particles and emulsion in the silver removing solution are flocculated, agglomerated and settled under the action of a flocculating agent PAM to obtain mixed slurry containing silver powder and the emulsion, wherein the emulsion mainly comprises gelatin which is a dispersant and a surfactant.
In the step, the flocculating agent PAM is a cationic polyacrylamide solution, the concentration of the cationic polyacrylamide solution is 0.1-0.2%, and the addition amount of the cationic polyacrylamide solution is 0.5-1% of the mass of the silver removing solution.
And S3, adding the mixed slurry into a glycerol aqueous solution at normal temperature, gradually heating and stirring until the temperature reaches the first temperature.
In the step, the mass fraction of the glycerol in the glycerol aqueous solution is preferably 5-10%.
In the step, the first temperature is selected to be 50-70 ℃, and preferably 60 +/-5 ℃.
And S4, keeping the temperature under the first temperature condition to dissolve the mixed slurry into the glycerol aqueous solution and form a uniform solution.
In the step, the first temperature is selected to be 50-70 ℃, and preferably 60 +/-5 ℃.
And S5, heating the uniform solution to a second temperature, preserving heat, and hydrolyzing the emulsion under the ultrasonic oscillation condition until silver particles are settled in the uniform solution.
In this step, the second temperature is selected to be 80-120 ℃, preferably 100-110 ℃.
In the step, in order to facilitate observation of the settlement of the silver particles in the uniform solution, the hydrolysis treatment is preferably performed on the uniform solution by adopting intermittent ultrasonic oscillation. For example: and during operation, stopping the ultrasonic vibration for 5min after each ultrasonic vibration treatment for 5min, observing the settling velocity of the silver particles and the agglomeration condition of the silver particles in the uniform solution in the process of stopping the ultrasonic vibration, and stopping the ultrasonic vibration to finish the hydrolysis process when the silver particles in the solution are obviously settled and the agglomeration of the silver particles is not generated.
It should be noted here that when agglomeration of silver particles in the solution is observed, it is indicated that excessive hydrolysis of the emulsion in the homogeneous solution affects the purity of the first-grade crude silver powder in step S6, which is described below, and that a surfactant may be properly added to the solution to inhibit agglomeration of silver particles and ensure sedimentation of silver particles.
S6, cooling the reaction liquid to a third temperature in the step S5, and filtering and separating the precipitate to obtain the first-grade crude silver powder. In the step, the third temperature is selected to be 70-90 ℃, and preferably 80 +/-5 ℃.
And S7, purifying, washing, filtering and drying the primary coarse silver powder to obtain the superfine silver powder.
In the step, the process of purifying, washing, filtering and drying the primary coarse silver powder to obtain the superfine silver powder comprises the steps of firstly dissolving the primary coarse silver powder in a 50% acetic acid solution, stirring for about 10min, and separating to obtain the secondary coarse silver powder; and secondly, washing the secondary coarse silver powder with an ethanol solution for 2-3 times, filtering, and drying a filter cake at 50 ℃ to obtain the superfine silver powder.
The present embodiment also provides another method for preparing ultrafine silver powder using a waste photosensitive film, and the present embodiment is different from the method for preparing ultrafine silver powder of fig. 1 in that the plastic film base in step S1 is washed again to improve the recovery rate of silver particles. Referring specifically to fig. 2, the plastic substrate separated in step S1 is subjected to a washing process, and the separated washing solution and the desilvering solution are combined and then processed in step S2. In the step, cleaning solution (such as deionized water) is selected to carry out ultrasonic oscillation cleaning on the plastic base to obtain the transparent plastic base, at the moment, silver powder adhered to the plastic base is separated from the cleaning solution and enters the cleaning solution, and the cleaned plastic base can be used as recycled plastic for subsequent treatment.
The method for preparing ultrafine silver powder by using waste photosensitive films designed by the specific embodiment is characterized in that in the process from step S3 to step S6, the emulsion in the mixed slurry is hydrolyzed, and simultaneously the hydrolysis degree of the emulsion is controlled to ensure the sedimentation of the primary coarse silver powder, and the action principle is as follows: through the control of factors such as the first temperature, the second temperature, the third temperature, the ultrasonic oscillation and the like, when the silver particle sedimentation phenomenon occurs, the emulsion in the mixed slurry is partially hydrolyzed to avoid excessive hydrolysis of the emulsion, and when the silver particle sedimentation phenomenon occurs, the residual emulsion can play a role of a surfactant, so that the sedimentary silver particles are dispersed to avoid agglomeration, and the purity of the primary coarse silver powder is further ensured.
The above method for preparing ultrafine silver powder using a waste photosensitive film is described below by way of specific examples.
Example 1:
taking 100g of waste photosensitive film, crushing, adding 100ml of 3.5% sodium hydroxide solution, carrying out ultrasonic oscillation treatment under the condition of 200-300 Hz, and filtering to obtain a silver removing solution and a plastic film base; adjusting the pH value of the silver removing solution to 2.5-3.0 by using a sulfuric acid solution, and adding a cationic polyacrylamide solution accounting for 0.1% of the weight of the silver removing solution by 0.5% for sedimentation treatment to obtain mixed slurry containing silver powder and an emulsion;
adding the mixed slurry into a glycerol aqueous solution with the mass fraction of 5.5% at normal temperature, heating to 60 ℃ while stirring, and preserving heat to dissolve the mixed slurry into the glycerol aqueous solution to form a uniform solution; heating the uniform solution to 95 ℃, preserving the temperature and hydrolyzing the emulsion by adopting an intermittent ultrasonic oscillation mode; when the silver particles in the solution are obviously settled but the silver particle agglomeration does not occur, the reaction is stopped;
cooling the solution to 75 ℃, and filtering at 75 ℃ to obtain a filter cake, namely the first-grade crude silver powder;
and (3) treating the primary coarse silver powder by adopting a 50% acetic acid solution and an ethanol solution in sequence, filtering, and drying a filter cake at 50 ℃ to obtain the superfine silver powder.
Example 2:
taking 200g of waste photosensitive film, crushing, adding 250ml of 4.5% sodium hydroxide solution, carrying out ultrasonic oscillation treatment under the condition of 200-300 Hz, and filtering to obtain a silver removing solution and a plastic film base; adjusting the pH value of the silver removing solution to 3.5-4.5 by using a sulfuric acid solution, and adding a cationic polyacrylamide solution accounting for 0.18 percent of the weight of 1.0 percent of the silver removing solution for sedimentation treatment to obtain mixed slurry containing silver powder and an emulsion;
adding the mixed slurry into a glycerol aqueous solution with the mass fraction of 10.0% at normal temperature, heating to 70 ℃ while stirring, and preserving heat to dissolve the mixed slurry into the glycerol aqueous solution to form a uniform solution; heating the uniform solution to 115 ℃, preserving the temperature and hydrolyzing the emulsion by adopting an intermittent ultrasonic oscillation mode; when the silver particles in the solution are obviously settled but the silver particle agglomeration does not occur, the reaction is stopped;
cooling the solution to 85 ℃, and filtering at 85 ℃ to obtain a filter cake, namely the first-grade crude silver powder;
and (3) treating the primary coarse silver powder by adopting a 50% acetic acid solution and an ethanol solution in sequence, filtering, and drying a filter cake at 50 ℃ to obtain the superfine silver powder.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (8)
1. A method for preparing superfine silver powder by using waste photosensitive films is characterized by comprising the following steps: the method comprises the following steps:
s1, adding the waste photosensitive film into a sodium hydroxide solution for ultrasonic oscillation treatment, and filtering to obtain a silver-removing solution and a plastic film base;
s2, adjusting the pH value of the silver removing solution to 2-5 by using a sulfuric acid solution, adding a flocculating agent PAM, stirring, standing, and separating to obtain a mixed slurry containing silver powder and an emulsion;
s3, adding the mixed slurry into glycerol aqueous solution at normal temperature, gradually heating and stirring until the temperature reaches a first temperature;
s4, preserving heat under the first temperature condition to enable the mixed slurry to be dissolved into the glycerol aqueous solution and form a uniform solution;
s5, heating the uniform solution to a second temperature, preserving heat, and hydrolyzing the emulsion under the ultrasonic oscillation condition until silver particles are settled in the uniform solution;
s6, cooling the reaction liquid to a third temperature in the step S5, and filtering and separating precipitates to obtain first-grade crude silver powder;
and S7, purifying, washing, filtering and drying the primary coarse silver powder to obtain the superfine silver powder.
2. The method for preparing ultrafine silver powder using waste photosensitive film according to claim 1, wherein: in the step S3, the mass fraction of the glycerol in the glycerol aqueous solution is 5-10%.
3. The method for preparing ultrafine silver powder using waste photosensitive film according to claim 1, wherein: in step S2, the flocculant PAM is a cationic polyacrylamide solution, the concentration of the cationic polyacrylamide solution is 0.1% to 0.2%, and the addition amount of the cationic polyacrylamide solution is 0.5% to 1% of the mass of the silver removing solution.
4. The method for preparing ultrafine silver powder using waste photosensitive film according to claim 1, wherein: in the method for preparing the superfine silver powder by using the waste photosensitive film, the plastic film base separated in the step S1 is washed, and the separated washing liquid is combined with the desilvering liquid.
5. The method for preparing ultrafine silver powder using waste photosensitive film according to claim 1, wherein: in step S5, the uniform solution is hydrolyzed by intermittent ultrasonic oscillation.
6. The method for preparing ultrafine silver powder using waste photosensitive film according to any one of claims 1 to 5, wherein: in step S1, the waste photosensitive film is subjected to ultrasonic oscillation treatment at 30-50 ℃.
7. The method for preparing ultrafine silver powder using waste photosensitive film according to any one of claims 1 to 5, wherein: the first temperature is 50-70 ℃, the second temperature is 80-120 ℃, and the third temperature is 70-90 ℃.
8. The method for preparing ultrafine silver powder using waste photosensitive film according to claim 7, wherein: the first temperature is 60 +/-5 ℃, the second temperature is 100-110 ℃, and the third temperature is 80 +/-5 ℃.
Priority Applications (1)
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| 李安民: "《固体废物循环管理研究：基于上海市循环经济发展》", 甘肃科学技术出版社, pages: 201 - 202 * |
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