CN116892044A - Purification process of metallic silver - Google Patents
Purification process of metallic silver Download PDFInfo
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- CN116892044A CN116892044A CN202310414613.9A CN202310414613A CN116892044A CN 116892044 A CN116892044 A CN 116892044A CN 202310414613 A CN202310414613 A CN 202310414613A CN 116892044 A CN116892044 A CN 116892044A
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- 229910052709 silver Inorganic materials 0.000 title claims abstract description 130
- 239000004332 silver Substances 0.000 title claims abstract description 130
- 238000000746 purification Methods 0.000 title claims abstract description 26
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 129
- MHUWZNTUIIFHAS-XPWSMXQVSA-N 9-octadecenoic acid 1-[(phosphonoxy)methyl]-1,2-ethanediyl ester Chemical compound CCCCCCCC\C=C\CCCCCCCC(=O)OCC(COP(O)(O)=O)OC(=O)CCCCCCC\C=C\CCCCCCCC MHUWZNTUIIFHAS-XPWSMXQVSA-N 0.000 claims abstract description 28
- ZGTMUACCHSMWAC-UHFFFAOYSA-L EDTA disodium salt (anhydrous) Chemical compound [Na+].[Na+].OC(=O)CN(CC([O-])=O)CCN(CC(O)=O)CC([O-])=O ZGTMUACCHSMWAC-UHFFFAOYSA-L 0.000 claims abstract description 28
- 238000005868 electrolysis reaction Methods 0.000 claims abstract description 28
- 229940047047 sodium arsenate Drugs 0.000 claims abstract description 28
- 239000003109 Disodium ethylene diamine tetraacetate Substances 0.000 claims abstract description 20
- 235000019301 disodium ethylene diamine tetraacetate Nutrition 0.000 claims abstract description 20
- 239000003792 electrolyte Substances 0.000 claims abstract description 18
- 239000002245 particle Substances 0.000 claims abstract description 16
- 239000000463 material Substances 0.000 claims abstract description 15
- 229910052751 metal Inorganic materials 0.000 claims abstract description 14
- 239000002184 metal Substances 0.000 claims abstract description 14
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910017604 nitric acid Inorganic materials 0.000 claims abstract description 7
- 238000003756 stirring Methods 0.000 claims abstract description 7
- 230000001502 supplementing effect Effects 0.000 claims abstract description 4
- 238000000034 method Methods 0.000 claims description 41
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 claims description 36
- 229910001961 silver nitrate Inorganic materials 0.000 claims description 18
- 230000000737 periodic effect Effects 0.000 claims description 9
- 238000001035 drying Methods 0.000 claims description 4
- 238000005406 washing Methods 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 abstract description 6
- 239000002994 raw material Substances 0.000 abstract description 5
- 230000000052 comparative effect Effects 0.000 description 13
- 239000012535 impurity Substances 0.000 description 10
- 238000001556 precipitation Methods 0.000 description 7
- 230000002195 synergetic effect Effects 0.000 description 6
- 238000001514 detection method Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 229910000510 noble metal Inorganic materials 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 230000008021 deposition Effects 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 241001506047 Tremella Species 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 229910001316 Ag alloy Inorganic materials 0.000 description 1
- 229910001200 Ferrotitanium Inorganic materials 0.000 description 1
- FOIXSVOLVBLSDH-UHFFFAOYSA-N Silver ion Chemical compound [Ag+] FOIXSVOLVBLSDH-UHFFFAOYSA-N 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000005034 decoration Methods 0.000 description 1
- 238000005238 degreasing Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000001036 glow-discharge mass spectrometry Methods 0.000 description 1
- PQTCMBYFWMFIGM-UHFFFAOYSA-N gold silver Chemical compound [Ag].[Au] PQTCMBYFWMFIGM-UHFFFAOYSA-N 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000012452 mother liquor Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 229940083025 silver preparation Drugs 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 230000009044 synergistic interaction Effects 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
- C25C1/20—Electrolytic production, recovery or refining of metals by electrolysis of solutions of noble metals
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
- C25C7/06—Operating or servicing
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electrolytic Production Of Metals (AREA)
Abstract
The application specifically discloses a purification process of metallic silver, which comprises the following steps: firstly, adding crushed silver material with purity of more than 99% into a nitric acid-containing container according to a proportion, and stirring and dissolving to form solution A; then adding sodium arsenate and disodium ethylenediamine tetraacetate into the solution A in the first step in proportion to form a solution B; secondly, putting the crushed silver material with the purity of more than 99% into a filter bag, putting the filter bag into an electrolytic tank to serve as an anode, taking silver flakes as a cathode, and adding the solution B in the step two as electrolyte to carry out electrolysis; then, continuously supplementing silver particles when about two thirds of silver particles in the filter bag are left, and obtaining metallic silver with purity of more than 99.9999% on the cathode after electrolysis for 2-2.5 h; finally, the metal silver in the fourth step is taken out and washed, and is stored after being dried, so that the silver jewelry raw material with lower purity can be directly adopted for electrolytic purification, the purity of the silver can be effectively met, and the production benefit is greatly improved.
Description
Technical Field
The application relates to the field of metal silver preparation, in particular to a metal silver purification process.
Background
Silver is an important industrial raw material and has very wide application. The high-purity silver has good electric conductivity and heat conductivity, and is an excellent electric conductor and heat conductor.
With the development of economy, the requirements on the purity of silver are also increasing, and silver with extremely high purity has many important industrial applications, wherein in the production and processing of noble metal jewelry such as gold, silver and the like, noble metals are manufactured into jewelry through various processing modes, and the processing more or less causes the loss of noble metals and the increase of impurities. Because the noble metal jewelry has higher gold and silver content, the recovery value is relatively higher.
At present, many methods for purifying silver, such as an electrolytic method, a chemical method, an ion exchange method, an extraction method and the like, are available. Wherein, the electrolytic method is green and environment-friendly and has higher efficiency, so the electrolytic method has better purifying effect. The silver content of the product electrolyzed by the electrolytic method is more than 99.0 percent, and after washing and drying, the product is cast into ingots with the silver content of more than 99.99 percent.
The existing silver electrolysis takes gold-silver alloy as an anode, coats a diaphragm bag, takes pure silver sheets, titanium or stainless steel sheets as a cathode, takes silver nitrate solution as electrolyte, utilizes the potential difference of each element to carry out impurity removal refining, does not dissolve impurities with higher potential than silver into anode mud, and changes elements with lower potential than silver into ions to be dissolved and remain in mother liquor. However, at present, high-purity silver with purity up to 99.9999% is obtained by controlling electrolysis parameters, but the requirements on raw materials are high, so that most of precious metal jewelry products are recovered by adopting a chemical method for smelting and purifying, if the purity of silver needs to be improved, the silver needs to be purified for multiple times, and the process is complex.
Disclosure of Invention
In order to effectively simplify the steps of the silver purification process and obtain silver with the purity meeting the requirement, the application provides a metal silver purification process.
In a first aspect, the application provides a process for purifying metallic silver, which adopts the following technical scheme:
a process for purifying metallic silver, comprising the steps of:
firstly, adding crushed silver materials with purity of more than 99% into a nitric acid-containing container in proportion, and stirring and dissolving to form a solution A;
step two, adding sodium arsenate and disodium ethylenediamine tetraacetate into the solution A in the step one in proportion to form a solution B;
step three, putting the crushed silver material with the purity of more than 99% into a filter bag, putting the filter bag into an electrolytic tank to serve as an anode, taking silver flakes as a cathode, and adding the solution B in the step two as electrolyte to carry out electrolysis;
continuously supplementing silver particles when about two thirds of silver particles in the filter bag remain, and electrolyzing for 2-2.5 h to obtain metal silver with purity of over 99.9999% on the cathode;
and fifthly, taking out and washing the metal silver in the fourth step, drying and storing the metal silver.
By adopting the technical scheme, the sodium arsenate and the disodium ethylenediamine tetraacetate are used as the conductive salt to carry out cooperative coordination with the silver nitrate, so that the current efficiency and the electrolysis efficiency can be effectively improved, the precipitation of impurities in the electrolyte is reduced, and compared with the existing process for electrolytically purifying the silver, the method can directly adopt crushed silver jewelry raw materials to carry out electrolytic purification, simultaneously can effectively ensure that the purity of the electrolytically purified silver meets the requirement of 99.9999 percent of high-purity silver, and greatly improves the production benefit.
Preferably, in the second step, the mass ratio of the sodium arsenate to the disodium ethylenediamine tetraacetate is (2.4-3.2): 1.
Preferably, the concentration of silver nitrate in the solution B is 180g/L-200g/L, the concentration of sodium arsenate is 5.3g g/L-7.2g/L, and the concentration of disodium ethylenediamine tetraacetate is 1.3g/L-4.5g/L
By adopting the technical scheme, after the concentration of the silver nitrate, the sodium arsenate and the disodium ethylenediamine tetraacetate in the solution B and the mass ratio of related substances are controlled, the synergistic coordination effect between the sodium arsenate and the disodium ethylenediamine tetraacetate after being compounded and the silver nitrate can be better improved, so that the current efficiency and the electrolysis efficiency in the solution B during electrolysis are further increased.
Preferably, the pH value of the electrolyte in the third step is 3.0-4.0.
Preferably, the electrolyte in the third step is subjected to periodic reverse electrolysis at a temperature of 20-40 ℃.
Preferably, the conditions of the periodic reverse electrolysis treatment are as follows: the forward current density was 300A/m 2 -450A/m 2 The high-level duration of the current pulse width is 15ms-30ms, and the low-level duration of the current pulse width is 1ms-10ms; the reverse current density was 120A/m 2 -220A/m 2 The high level duration and the low level duration of the current pulse width are 1ms-4ms.
By adopting the technical scheme, the method of periodic reverse electrolysis can effectively reduce impurity precipitation, improve the current density and the deposition rate of the cathode, control the pH value of the electrolyte to 3.0-4.0 and control the intensity of current, and can better reduce the precipitation of impurity elements such as copper, lead and the like at the cathode so as to further achieve the aim of improving the purity of silver.
Preferably, when the electrolysis is carried out in the third step, the cell voltage is 1-1.5V, and the current density is 300-400A/square meter.
By adopting the technical scheme, after the voltage and the current are controlled in the specified range, the synergistic cooperation effect between the sodium arsenate and the disodium ethylenediamine tetraacetate after being compounded and the silver nitrate can be further enhanced, so that the purpose of improving the electrolysis efficiency is achieved.
Preferably, the granularity of the crushed silver material is 280-550 meshes.
Preferably, the silver material is at least one of silver bracelets, silver earrings and silver necklaces.
By adopting the technical scheme, the recovered silver bracelets, silver earrings and silver necklaces are used as silver materials and crushed to a specific granularity range, so that the purification time can be effectively shortened, and the purification efficiency of the recovered silver materials is better improved.
In summary, the application has the following beneficial effects:
1. the sodium arsenate and the disodium ethylenediamine tetraacetate are used as the conductive salt to carry out cooperative coordination with the silver nitrate, so that the current efficiency and the electrolysis efficiency can be effectively improved, and the precipitation of impurities in the electrolyte is reduced;
2. by controlling the concentration of silver nitrate, sodium arsenate and disodium edetate in the solution B and the mass ratio of related substances, the synergistic effect between the compounded sodium arsenate and disodium edetate and the silver nitrate can be better improved, so that the current efficiency and the electrolysis efficiency in the solution B during electrolysis are further increased;
3. the method can effectively reduce impurity precipitation by utilizing a periodic reverse electrolysis method, and simultaneously improve the current density and the deposition rate of a cathode, and in addition, the pH value of the electrolyte is controlled to be 3.0-4.0, and the intensity of current is controlled, so that the precipitation of impurity elements such as copper, lead and the like on the cathode can be better reduced, and the aim of improving the purity of silver is further achieved;
4. the voltage and the current are controlled in the specified range, so that the synergistic effect between the sodium arsenate and the disodium edetate and the silver nitrate after being compounded can be further enhanced, and the aim of improving the electrolysis efficiency is fulfilled.
Detailed Description
The present application will be described in further detail with reference to examples and comparative examples.
The raw materials used in the following examples and comparative examples are all commercially available products.
Examples
Example 1
A process for purifying metallic silver, comprising the steps of:
step one, cleaning and degreasing silver bracelet silver material with the purity of 99%, crushing, sieving with a 220-mesh sieve to obtain silver particles with the average particle size of 220 meshes, adding a part of silver particles into a nitric acid-containing container according to a reaction proportion, and stirring and dissolving to form a solution A;
adding sodium arsenate and disodium ethylenediamine tetraacetate into the solution A in the step one according to the mass ratio of 2:1, adding nitric acid, stirring and mixing to form a solution B with the pH value of 4.5 and the concentrations of silver nitrate, sodium arsenate and disodium ethylenediamine tetraacetate of 170g/L, 7.5g/L and 5g/L respectively;
step three, putting the other part of silver particles left in the step one into a filter bag and putting the filter bag into an electrolytic tank to serve as an anode, taking silver flakes as a cathode, adding the solution B in the step two as electrolyte, and carrying out electrolysis at the tank voltage of 2.5V and the current density of 500A per square meter;
continuously supplementing silver particles when about two thirds of silver particles in the filter bag remain, continuously electrolyzing for 2 hours, and obtaining metallic silver on the cathode;
and fifthly, taking out and washing the metal silver in the fourth step, drying and storing the metal silver.
Example 2
The purification process of metallic silver is different from example 1 in that the electrolysis time in step four is 2.5h.
Example 3
A process for purifying metallic silver is different from example 2 in that the ratio of sodium arsenate to disodium ethylenediamine tetraacetate is 2.4:1.
Example 4
A process for purifying metallic silver is different from example 2 in that 3.6:1 of sodium arsenate and disodium ethylenediamine tetraacetate are used.
Example 5
A process for purifying metallic silver differs from example 2 in that the concentrations of silver nitrate, sodium arsenate and disodium ethylenediamine tetraacetate are 180g/L, 7.2g/L and 4.5g/L, respectively.
Example 6
A process for purifying metallic silver differs from example 2 in that the concentrations of silver nitrate, sodium arsenate and disodium ethylenediamine tetraacetate are 200g/L, 5.3g/L and 1.3g/L, respectively.
Example 7
A process for purifying metallic silver differs from example 2 in that the concentrations of silver nitrate, sodium arsenate and disodium ethylenediamine tetraacetate are 180g/L, 7.2g/L and 4.5g/L, respectively.
Example 8
A process for purifying metallic silver is different from example 2 in that nitric acid is added in step two, stirring and mixing are carried out to form pH value of 4.0, and meanwhile, the electrolyte in step three is subjected to periodic reverse electrolysis treatment at 40 ℃, wherein forward current density is 300A/m 2 The high-level duration of the current pulse width is 15ms, the low-level duration of the current pulse width is 1ms, and the reverse current density is 120A/m 2 The high level duration and the low level duration of the current pulse width are both 1ms.
Example 9
A process for purifying metallic silver is different from example 2 in that nitric acid is added in step two, stirring and mixing are carried out to form pH value of 3.0, and meanwhile, the electrolyte in step three is subjected to periodic reverse electrolysis treatment at 20 ℃, wherein forward current density is 450A/m 2 The high-level duration of the current pulse width is 30ms, the low-level duration of the current pulse width is 10ms, and the reverse current density is 220A/m 2 The current pulse width high level duration and the low level duration are both 4ms.
Example 10
A process for purifying metallic silver differs from example 2 in that the bath voltage in step three is 1.5V, the current density is 400A per square meter, and the average particle size of the silver is 550 mesh.
Example 11
A process for purifying metallic silver differs from example 2 in that the bath voltage in step three is 1V, the current density is 300A per square meter, and the average particle size of the silver is 280 mesh.
Example 12
A process for purifying metallic silver is different from example 2 in that the silver bracelet is replaced by tremella ornament.
Example 13
The purification process of metallic silver is different from example 2 in that the silver bracelets are replaced with silver necklaces.
Comparative example
Comparative example 1
The purification process of metallic silver differs from example 1 in that solution B in step two does not contain sodium arsenate.
Comparative example 2
The purification process of metallic silver is different from example 1 in that solution B in step two does not contain disodium edetate.
Comparative example 3
The purification process of metallic silver is different from that of example 1 in that the solution B in the second step does not contain sodium arsenate and disodium ethylenediamine tetraacetate.
Performance test
Purity values of the purified metallic silver in the processes of examples 1-13 and comparative examples 1-3 were measured using a GD-MS glow discharge mass spectrometer.
Table 1-summary of test data for examples 1-13 and comparative examples 1-3
| Purity of | |
| Example 1 | 99.99994% |
| Example 2 | 99.99995% |
| Example 3 | 99.99997% |
| Example 4 | 99.99998% |
| Example 5 | 99.99996% |
| Example 6 | 99.99996% |
| Example 7 | 99.99997% |
| Example 8 | 99.99998% |
| Examples9 | 99.99999% |
| Example 10 | 99.99995% |
| Example 11 | 99.99996% |
| Example 12 | 99.99995% |
| Example 13 | 99.99995% |
| Comparative example 1 | 99.9995% |
| Comparative example 2 | 99.9994% |
| Comparative example 3 | 99.9992% |
As can be seen from comparison of the detection data of the embodiment 1 and the comparative example 3 in the table 1, compared with the existing process of directly adopting low-purity silver jewelry to carry out electrolytic purification, the purity of the purified metallic silver is greatly improved, so that the optimization step before the silver jewelry purification treatment can be better saved while the purity of the electrolytic metallic silver is effectively improved, the production benefit is effectively improved, and the method has great economic value for the purification production of the metallic silver of enterprises.
In addition, as can be seen from comparison of the test data of example 1 and comparative examples 1 to 3 in table 1, if the synergistic coordination relationship between sodium arsenate and disodium ethylenediamine tetraacetate is destroyed in the electrolyte system, the effects between the sodium arsenate and disodium ethylenediamine tetraacetate of the present application after being compounded and silver nitrate cannot be exerted, so that the purity of the metallic silver obtained after electrolytic purification is greatly reduced, which means that the two are indispensable, and further it is known that the precondition that the purity of the metallic silver of the present application can be improved is that the synergistic interaction between the two is required, so as to obtain more effective synergistic effect on the silver nitrate electrolyte.
According to comparison of the detection data of examples 2 to 7 in table 3, after the addition ratio of sodium arsenate and disodium edetate or the concentration of silver nitrate, sodium arsenate and disodium edetate are controlled, the purity value of the electrolytic metallic silver can be further improved on the basis of example 2 to different degrees so as to further optimize the purification production process of the application.
According to comparison of the detection data of examples 2 and 8-9 in table 1, the method of periodic reverse electrolysis treatment is adopted to purify the metallic silver on the basis of the process of example 2, and after the relevant electrolysis parameter conditions are controlled, the precipitation of impurities can be effectively reduced, the density of current in the electrolyte is improved, and the cathode deposition rate is improved, so that the metallic silver with higher purity value can be obtained to a greater extent, and the aim of improving the purification efficiency is fulfilled.
From comparison of the test data of examples 2 and 10-11 in table 3, it is known that by further controlling and adjusting the cell voltage, current density and average particle size of the silver material during electrolysis, electrolytic metallic silver with higher purity can be obtained on the basis of the process of example 2, thereby being more advantageous for optimizing the metallic silver purification process of the present application.
According to comparison of the detection data of examples 2 and 12-13 in Table 3, when tremella decorations or silver necklaces are selected to replace the silver bracelets in example 2, the purity of the metal silver obtained by electrolysis of the silver material is not different, so that the electrolytic metal silver purification process can be applied to electrolytic purification of most silver jewelry, achieves the aim of facilitating efficient purification of different types of silver jewelry by people, and has great economic benefit.
The present embodiment is only for explanation of the present application and is not to be construed as limiting the present application, and modifications to the present embodiment, which may not creatively contribute to the present application as required by those skilled in the art after reading the present specification, are all protected by patent laws within the scope of claims of the present application.
Claims (9)
1. A process for purifying metallic silver, comprising the steps of:
firstly, adding crushed silver materials with purity of more than 99% into a nitric acid-containing container in proportion, and stirring and dissolving to form a solution A;
step two, adding sodium arsenate and disodium ethylenediamine tetraacetate into the solution A in the step one in proportion to form a solution B;
step three, putting the crushed silver material with the purity of more than 99% into a filter bag, putting the filter bag into an electrolytic tank to serve as an anode, taking silver flakes as a cathode, and adding the solution B in the step two as electrolyte to carry out electrolysis;
continuously supplementing silver particles when about two thirds of silver particles in the filter bag remain, and electrolyzing for 2-2.5 h to obtain metal silver with purity of over 99.9999% on the cathode;
and fifthly, taking out and washing the metal silver in the fourth step, drying and storing the metal silver.
2. The process for purifying metallic silver as recited in claim 1, wherein the mass ratio of sodium arsenate to disodium edetate in the second step is (2.4-3.2): 1.
3. The process for purifying metallic silver according to claim 1, wherein the concentration of silver nitrate in the solution B is 180g/L to 200g/L, the concentration of sodium arsenate is 5.3g g/L to 7.2g/L, and the concentration of disodium edetate is 1.3g/L to 4.5g/L.
4. The process according to claim 1, wherein the pH of the electrolyte in the third step is 3.0-4.0.
5. The process according to claim 4, wherein the electrolyte in the third step is subjected to periodic reverse electrolysis at a temperature of 20-40 ℃.
6. The process for purifying metallic silver as recited in claim 5, wherein the conditions of the periodic reverse electrolytic treatment are: the forward current density was 300A/m 2 -450A/m 2 The high-level duration of the current pulse width is 15ms-30ms, and the low-level duration of the current pulse width is 1ms-10ms; the reverse current density was 120A/m 2 -220A/m 2 The high level duration and the low level duration of the current pulse width are 1ms-4ms.
7. The process according to claim 1, wherein the step three is performed with a cell voltage of 1-1.5V and a current density of 300-400A/square meter.
8. The process for purifying metallic silver as recited in claim 1, wherein the crushed silver material has a particle size of 280 mesh to 550 mesh.
9. The method for preparing a metallic silver purification process according to claim 1, wherein the silver material is at least one of silver bracelets, silver earrings and silver necklaces.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310414613.9A CN116892044A (en) | 2023-04-18 | 2023-04-18 | Purification process of metallic silver |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310414613.9A CN116892044A (en) | 2023-04-18 | 2023-04-18 | Purification process of metallic silver |
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| Publication Number | Publication Date |
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| CN116892044A true CN116892044A (en) | 2023-10-17 |
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| CN202310414613.9A Pending CN116892044A (en) | 2023-04-18 | 2023-04-18 | Purification process of metallic silver |
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