CN108149018A - The recovery method of Ag in a kind of Bi systems superconducting line strips - Google Patents

Abstract

The invention discloses a method for recovering Ag from Bi-based superconducting wire strips. The method is as follows: first remove the Bi-based superconducting wires containing silver or silver alloy to remove oil stains and coatings, and then perform heat treatment; then dissolve in In concentrated nitric acid, nitrate is evaporated and decomposed, and the whole is added with water, stirred and aged, and the filtered solution contains undecomposed silver nitrate, strontium nitrate, calcium nitrate, and a small part of basic salt of bismuth, and concentrated hydrochloric acid is added dropwise to the solution to form chlorinated Silver precipitation, place it away from light for aging, filter the precipitate, transfer it to a container, add concentrated ammonia water to cover the precipitate, heat to boiling, slowly add hydrazine hydrate under stirring, until no precipitate is produced, filter, dry, and obtain the quality Sponge silver powder with a purity of more than 99.95%, and a recovery rate of not less than 99%. The invention is suitable for recovering silver in silver-containing sheaths of single-core and multi-core Bi systems, and can obtain silver sponge powder with batch production, high purity, and uniform and fine crystal grains.

Description

A kind of recovery method of Ag in Bi-based superconducting wire tape

technical field

The invention belongs to the technical field of silver recovery, and in particular relates to a method for recovering Ag from Bi-based superconducting wire strips.

Background technique

Superconducting materials are the basis for the application of superconducting technology. Low-temperature superconducting materials represented by NbTi and Nb ₃ Sn , medium-temperature superconducting materials represented by MgB ₂ , and BSCCO (Bi system) and YBCO (Y system) are representative. High-temperature superconducting materials have entered or semi-industrialized in recent years, and are widely used in fields such as electric power, communications, national defense, and medical treatment, and have application prospects with higher added value. The mature application of these technologies has gone through a long research and development process in the early stage, and a lot of manpower, material resources and financial resources have been invested. The Bi-based oxide superconductor was discovered in 1986. Due to its advantages in the application of liquid nitrogen in the 77K temperature range, scientific and technological workers from all over the world have devoted a lot of energy to it. A lot of detailed research has been done on this aspect. China established high-temperature superconducting technology as one of the three cutting-edge technologies of new material technology in the 2005 "National Medium and Long-Term Science and Technology Development Program Outline" (2006-2020) (smart materials and structures technology, high-temperature superconducting technology and high-efficiency energy material technology), foreign companies have also established large-scale production (ASC Corporation of the United States, Sumitomo Corporation of Japan, Trithor Corporation of Germany, with an annual output of more than 5000Km, worth 200 million US dollars).

Among the above-mentioned high-temperature superconducting oxides, Bi-2223 and Bi-2212 use silver or silver alloy as the sheath material to prepare wire strips. As a basic research, study the phase formation mechanism of its wire strips and the preparation of precursor powders , wire and strip processing and heat treatment, alloy sheath material, magnetic flux pinning of wire and strip, AC loss of wire and strip; as engineering application research its batch powder preparation technology, thermal insulation coating of long strip technology, electrical insulation coating technology for finished long strips, and WIT technology for improving the mechanical properties of strips. The research and development of each technology needs to prepare samples for testing to judge the feasibility of the technology, so a large number of research and development samples are left, and more than 70% of the samples are silver, and the rest are superconducting phases. Silver is a precious metal, and the price of silver tubes is higher. In order to reduce the cost and loss of research and development, it is very necessary to recycle the discarded silver strips after purification experiments. The purified silver can continue to play a role in scientific research and industrial production.

Generally, there are fire method and wet method for the purification of silver-containing waste. The fire method has high smelting temperature (1000-1100 ℃), high energy consumption and high cost. It needs to add flux to improve the fluidity of the material, but it is not satisfactory in practice. Due to the fluxing effect, it is difficult to separate the slag more effectively, and the recovery rate is low. There are many wet purification methods, including electrolysis and chemical purification. The recovery cycle of electrolysis is long, labor-intensive, complex scientific research samples are not easy to fix electrolysis parameters, and the recovery rate is uncertain. Chemical purification needs to select suitable reagents according to the composition of the sample. Some of these reagents need to be calcined at high temperature after reacting with silver, or heated in vacuum, and some add alkali solution to AgCl, but for a small amount of bismuth dissolved in the solution, it is initially When washing, it needs to be in an acidic environment to ensure that it will not be hydrolyzed to form precipitates, otherwise it will be mixed with silver chloride to affect the subsequent reduction purity. However, the chemical method has a wide range of applications, and it is easy to adjust the preparation parameters according to the characteristics of the elements. It is also especially suitable for small batches of laboratory recovery, and has flexible means.

Bi-based high-temperature superconducting oxides include Bi-2223 and Bi-2212. The former contains 4-5 chemical elements (Bi, Pb, Sr, Ca, Cu), and the latter contains the other 4 elements mentioned above except Pb. In order to improve the pinning performance, some other elements are often doped. In addition to pure silver sheathing materials, AgMg alloys and AgAu alloys are also developed. Therefore, in the process of chemical purification of silver in the presence of multiple elements, temperature control is a technical difficulty in recycling technology. The same recycling Technology contains different elements, each element interferes with each other, and each has its own reaction characteristics. If it is not well grasped, the purity of the final silver cannot be guaranteed.

It is found in the experiment that when nitric acid is used to decompose the Bi-based superconducting wire strip, the nitrate produced by the reaction is extremely sensitive to temperature. When it starts to dissolve, five or four elements first form nitrate. As the temperature gradually increases, different The temperature range experienced by the nitrate from hydrolysis, partial decomposition, and complete decomposition into oxides or simple substances is relatively large, between 50 ° C and 700 ° C, especially bismuth nitrate, which generates basic salts (Bi ₆ O ₆ ) ₂ (NO ₃ ) ₁₁ (OH).6H ₂ O precipitates, and part of the salt dissolves, and [Bi ₆ O ₆ ](NO ₃ ) ₆ .3H ₂ O is formed at 77℃～130℃, 400 ℃～500℃ decomposes into bismuth oxide. If high temperature is used to completely decompose into oxides, silver is mixed in the oxide powder as simple substance or silver oxide, and it is impossible to separate silver simple substance by liquid phase. The current silver recovery technologies recorded in the literature mainly include fixer, slag, metal alloys, etc., and the Bi-based superconducting materials that use silver or silver alloys as sheath materials contain about 30% of high-temperature superconducting oxide powder recovery technology There are few reports.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for recovering Ag in Bi-based superconducting wire strips in view of the above-mentioned deficiencies in the prior art. The recovery rate of metal Ag recovered by this recovery method is not less than 99%, and the purity is as high as 99.95%. It is sponge silver with uniform and fine crystal grains, and the spectral detection of 18 impurity elements in the recovered sponge silver is all below 0.001%. Bi is less than 0.0003 wt%, and Sr detected by ICP is less than 0.001 wt%.

For solving the problems of the technologies described above, the technical solution adopted in the present invention is: a method for recovering Ag in a Bi-based superconducting wire strip, characterized in that the method for recovering comprises the following steps:

Step 1, shortening the Bi-based superconducting wire strip, the Bi-based superconducting wire strip is a single-core or multi-core Bi-based superconducting wire made of a silver-containing sheath;

Step 2, first remove the surface coating and oil stains of the Bi-based superconducting wire strips that have been shortened in step 1, then use deionized water to wash and remove the Bi-based superconducting wire strips after oil stains, and finally use alcohol to dehydrate and dry;

Step 3. Place the Bi-based superconducting wire strip dried in Step 2 in a vacuum furnace, and heat-treat it for 2h-4h under the conditions of a vacuum degree of ^10-3 Pa and a temperature of 400°C-600°C to remove the Bi-based superconducting wire strip. Gas, moisture, and stress adsorbed inside the superconducting wire strip;

Step 4. Add the Bi-based superconducting wire strip after the heat treatment in step 3 to concentrated nitric acid and heat it to 150°C-155°C to keep it warm until a brown jelly is obtained, then add concentrated nitric acid and heat to 160°C-200°C Keep warm at ℃ until a dark brown jelly is obtained, then add distilled water and stir evenly, and finally leave it for 8h-10h to obtain a precipitate;

Step 5, filter the precipitated solution obtained in step 4 to obtain filter cake and filtrate, then use deionized water to rinse the filter cake until the filter cake is neutral, collect the deionized water after rinsing the filter cake and combine with the The filtrate is mixed to obtain a mixed solution;

Step 6. First heat the mixed solution in step 5 to 80°C-100°C, then add concentrated hydrochloric acid to the mixed solution for precipitation reaction (AgNO ₃ +HCl (concentrated)=AgCl↓+HNO ₃ ), and wait for precipitation After the reaction is completed, age in the dark for 5h to 8h, and then filter and wash to obtain a silver chloride filter cake, which is neutral;

Step 7. Slowly add ammonia water dropwise to the silver chloride filter cake obtained in step 6 until the silver chloride filter cake and ammonia water completely react (AgCl+2NH ₃ .H ₂ O=Ag(NH ₃ ) ₂ Cl+2H ₂ O) to generate silver diammine chloride solution, then heat the silver diammine chloride solution to boiling to remove excess ammonia water, then slowly add hydration solution dropwise to the silver diammine chloride solution under constant stirring. Hydrazine precipitation reaction (2Ag(NH ₃ ) ₂ Cl+2N ₂ H ₄ .H ₂ O=2Ag↓+2NH ₄ Cl+N ₂ ↑+4NH ₃ ↑+2H ₂ O) until no more precipitates are formed After the precipitation reaction is completed, the reaction solution is cooled, and finally filtered, washed and dried to obtain silver sponge.

The above-mentioned method for recovering Ag from Bi-based superconducting wire tapes is characterized in that: the Bi-based superconducting wire tapes described in step 1 are Bi-2223 superconducting wire tapes or Bi-2212 superconducting wire tapes.

The recovery method of Ag in the above-mentioned a kind of Bi-based superconducting wire strip is characterized in that: step 2 removes the specific process of the Bi-based superconducting wire surface coating and oil stain after being cut short in step 1 as: first mass concentration 22% to 25% concentrated ammonia water and deionized water are mixed evenly at a volume ratio of 1:10, and then used to soak the Bi-based superconducting wire strip until the coating on the surface is dissolved, then washed with deionized water for 4 times, and finally Use metal detergent to soak for 30 minutes to remove the oil stain on the surface of the Bi-based superconducting wire strip.

The method for recovering Ag in the above-mentioned Bi-based superconducting wire tape is characterized in that: the total volume of the concentrated nitric acid added twice in step 4 is 1 time of the quality of the Bi-based superconducting wire tape, adding the The volume of deionized water is 5 times of the quality of described Bi-based superconducting wire tape, the unit of the total volume of described concentrated nitric acid and the volume of deionized water are all mL, the quality of described Bi-based superconducting wire tape The unit is g, and the mass concentration of the concentrated nitric acid is 68%.

The method for recovering Ag in the above-mentioned a kind of Bi-based superconducting wire strip is characterized in that: a glass funnel covered with filter paper and filter cloth is adopted when filtering in step 5; funnel.

The method for recovering Ag in the above-mentioned Bi-based superconducting wire strip is characterized in that: the consumption of concentrated hydrochloric acid described in step 6 is to add 350mL to 400mL of concentrated hydrochloric acid for every 500 grams of Bi-based superconducting wire strip described in step 1. Hydrochloric acid, the mass concentration of described concentrated hydrochloric acid is 50%.

The above-mentioned method for recovering Ag from Bi-based superconducting wire strips is characterized in that: the mass concentration of hydrazine hydrate in step 7 is 50%-80%, and the drying temperature is 60°C.

Principle of the present invention:

The notable feature of the present invention is that four elements (Bi, Sr, Ca, Cu) or five elements (Bi, Pb, Sr, Ca, Cu) in the Bi-based superconducting wire strip are dissolved together with the sheathed silver or silver alloy. Nitrate is generated in nitric acid, and the superconducting oxide powder is dissolved in stages at a lower evaporation temperature of 150°C to 200°C in the present invention. The first stage is 150°C to 155°C, and the low temperature ensures that all the net materials in the wire strip are completely Dissolve and evenly generate nitrates. In the second stage at 160℃～200℃, the nitrates except Ag, Sr, and Ca will not decompose. They will be dissolved in water when they are aged, while Pb, Cu, and Bi will be dissolved in alkaline form respectively. The salt, partially decomposed, or partially hydrolyzed forms are precipitated in water and separated and removed, reducing the possibility of precipitation with silver caused by hydrochloric acid precipitation of silver as much as possible, and improving the purity of silver.

There have been several phenomena of nitrates: AgNO ₃ and Sr( _{NO 3} ) _{2 that} do not decompose when evaporated but can dissolve in water; Cu(NO ₃ ) ₂ decomposed or partially decomposed under the condition of 170℃～200℃ will appear insoluble and dissolved in the subsequent water; or Bi(NO ₃ ) ₃ decomposed by evaporation will be mostly insoluble in water Alkaline salts in water are precipitated, and a small amount of alkali salts may be dissolved in water at the same time. Therefore, it is necessary to control the acidolysis temperature of raw materials to prevent impurity elements from being mixed in the subsequent precipitation reaction and reduction reaction of silver, thereby reducing the purification degree of silver.

In order to achieve the purpose of recovering silver with high purity and to avoid the interference of other elements above, the technical solution adopted in the present invention is: first remove the oil and coating on the ^surface of the silver-containing Bi-based superconducting wire strip, Under certain conditions, the heat treatment temperature is 400°C-600°C, and the temperature is kept for 2-4 hours to remove the gas, moisture, and stress adsorbed inside the wire strip; then the sample is dissolved in concentrated nitric acid, and part of the nitrate is evaporated and decomposed at 150°C-200°C, and water is added to the whole Stir and age for 8-10 hours, filter the resulting solution containing undecomposed silver nitrate, strontium nitrate, calcium nitrate, and a small part of basic salt of bismuth, add concentrated hydrochloric acid to the solution under the condition of heating 80°C-100°C to generate chlorine Precipitate silver, place in the dark and age for 5-8 hours. Filter the precipitate, transfer it to a container, add concentrated ammonia water to cover the precipitate, heat to boiling, slowly add a small amount of hydrazine hydrate under stirring until no more precipitate is produced, and then get a sponge silver precipitate, filter, and dry at 60°C to obtain mass Sponge silver powder with a purity of more than 99.95%, and a recovery rate of not less than 99%.

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

1, the method cycle of the recovery Ag of the present invention is short, and energy consumption is low, does not have high-end complex equipment to be used in this method, and experimental operation process is simple simultaneously, and the recovery rate of metal Ag is not less than 99%, and purity is up to more than 99.95%, all It is sponge silver with uniform and fine grains.

2. The sponge silver recovered by the present invention is detected, and the mass content of 19 kinds of impurity elements detected is extremely low, wherein the mass content of Bi is less than 0.0003%, and the mass content of Sr is less than 0.001%, which is difficult to effectively reduce in the current technical recovery scheme. The mass content of Bi and Sr in recovered Ag.

3. The method of the present invention is specially designed for the Bi-based superconducting wire strip containing silver or silver alloy sheath, and controls the metal elements in the Bi-based superconducting wire strip to enter the subsequent Impurities are formed in the reaction solution, causing the problem that the purity of the metal Ag is not high.

4. The slag produced in the intermediate steps of the recovery method of the present invention is easily separated from the product obtained, and the slag can be repeatedly purified, which can improve the recovery rate of silver.

The technical solutions of the present invention will be further described in detail below through examples.

Detailed ways

Example 1

The method that present embodiment reclaims Ag comprises the following steps:

Step 1. Shorten 500 grams of Bi-2223 single-core superconducting tape with sterling silver sheath;

Step 2. First mix the concentrated ammonia water with a mass concentration of 25% and deionized water at a volume ratio of 1:10, and then use it to soak the Bi-2223 single-core superconducting tape until the coating on the surface is dissolved, and then use it to remove Wash with deionized water for 4 times, and finally use metal detergent to soak for 30 minutes to remove the oil on the surface of the Bi-2223 single-core superconducting tape. After the oil is removed, use deionized water to wash the Bi-2223 single-core superconducting tape after removing the oil. Finally, use alcohol to dehydrate and dry;

Step 3. Place the sample in a vacuum furnace, heat up to 400°C/4h after the vacuum degree reaches 10 ^-3 Pa;

Step 4. Add the Bi-2223 single-core superconducting tape after the heat treatment in Step 3 to 250mL of concentrated nitric acid and heat it to 150°C until a brown jelly is obtained, then add 250mL of concentrated nitric acid and heat to Keep warm at 160°C until dark brown jelly is obtained, then add 2500mL of distilled water and stir evenly, and finally leave it for 8 hours to obtain a precipitate;

Step 5, use a glass funnel covered with filter paper and filter cloth to filter the precipitated solution obtained in step 4 to obtain a filter cake and filtrate, then rinse the filter cake with deionized water until the filter cake is neutral, collect and rinse The deionized water behind the filter cake is mixed with the filtrate to obtain a mixed solution;

Step 6. First heat the mixed solution described in step 5 to 80°C, then add concentrated hydrochloric acid to the mixed solution for precipitation reaction, after the precipitation reaction is completed, age in the dark for 5 hours, and then use a cloth covered with two layers of filter paper Equation funnel carries out suction filtration, adopts deionized water to wash again to neutrality, obtains silver chloride filter cake; The mass concentration of described concentrated hydrochloric acid is 50%, and adding volume is 400mL;

Step 7, in the silver chloride filter cake that obtains in step 6, slowly add ammoniacal liquor dropwise, until silver chloride filter cake and ammoniacal liquor react completely, generate diammine silver chloride solution, then heat diammine silver chloride solution Remove excess ammonia water until boiling, and then slowly add hydrazine hydrate with a mass concentration of 50% to the silver diammine chloride solution under constant stirring to carry out the precipitation reaction until no more precipitates are generated. After the reaction was completed, the reaction solution was cooled, and finally filtered with a Buchner funnel, washed with deionized water, and dried at 60° C. to obtain silver sponge.

The mass purity of the silver sponge obtained by the recovery of this embodiment is 99.97%, wherein the mass content of impurities Sb, Fe, Mn, Mg, Pb, Sn, Au, Al, Ca, Ir, Rh, Pt, Pd, Sr is all less than 0.001 %, the mass content of impurities Ni, Si and Cu is 0.001%, the mass content of impurities Bi is less than 0.0003%, and the mass content of Zr is less than 0.002%.

Example 2

The method that present embodiment reclaims Ag comprises the following steps:

Step 1, shorten 500 grams of Bi-2223 multi-core superconducting wire with a silver-magnesium alloy sheath;

Step 2. First mix the concentrated ammonia water with a mass concentration of 25% and deionized water at a volume ratio of 1:10, and then use it to soak the Bi-2223 multi-core superconducting wire until the coating on the surface is dissolved, and then use deionized Wash with water 4 times, and finally use metal detergent to soak for 30 minutes to remove the oil on the surface of the Bi-2223 multi-core superconducting wire. After the oil is removed, use deionized water to wash the Bi-2223 multi-core superconducting wire after removing the oil. dehydrated and dried;

Step 3, placing the Bi-2223 multi-core superconducting wire dried in Step 2 in a vacuum furnace, and heat-treating for 3 hours under the conditions of a vacuum degree of 10 ⁻³ Pa and a temperature of 500° C.;

Step 4. Add the Bi-2223 multi-core superconducting wire after the heat treatment in step 3 to 250mL of concentrated nitric acid and heat it to 150°C until a brown jelly is obtained, then add 250mL of concentrated nitric acid and heat to 180°C Keep warm at ℃ until a dark brown jelly is obtained, then add 2500mL of distilled water and stir evenly, and finally leave it for 9 hours to obtain a precipitate;

Step 5, use a glass funnel covered with filter paper and filter cloth to filter the precipitated solution obtained in step 4 to obtain a filter cake and filtrate, then rinse the filter cake with deionized water until the filter cake is neutral, collect and rinse The deionized water behind the filter cake is mixed with the filtrate to obtain a mixed solution;

Step 6. First heat the mixed solution described in step 5 to 90°C, then add concentrated hydrochloric acid to the mixed solution for precipitation reaction, after the precipitation reaction is completed, age in the dark for 7 hours, and then use a cloth covered with two layers of filter paper Equation funnel carries out suction filtration, adopts deionized water to wash again to neutrality, obtains silver chloride filter cake; The mass concentration of described concentrated hydrochloric acid is 50%, and adding volume is 380mL;

Step 7, in the silver chloride filter cake that obtains in step 6, slowly add ammoniacal liquor dropwise, until silver chloride filter cake and ammoniacal liquor react completely, generate diammine silver chloride solution, then heat diammine silver chloride solution Remove excess ammonia water until boiling, and then slowly add hydrazine hydrate with a mass concentration of 50% to the silver diammine chloride solution under constant stirring to carry out the precipitation reaction until no more precipitates are generated. After the reaction was completed, the reaction solution was cooled, and finally filtered with a Buchner funnel, washed with deionized water, and dried at 60° C. to obtain silver sponge.

The mass purity of the silver sponge obtained by the recovery of this embodiment is 99.97%, wherein the mass content of impurities Sb, Fe, Mn, Mg, Pb, Sn, Au, Al, Ca, Ir, Rh, Pt, Pd, Sr is all less than 0.001 %, the mass content of impurities Ni, Si and Cu is 0.001%, the mass content of impurities Bi is less than 0.0003%, and the mass content of Zr is less than 0.002%.

Example 3

The method that present embodiment reclaims Ag comprises the following steps:

Step 1. Shorten 500 grams of Bi-2212 superconducting multi-core strip with silver-gold sheath;

Step 2. First mix the concentrated ammonia water with a mass concentration of 25% and deionized water at a volume ratio of 1:10, and then use it to soak the Bi-2212 superconducting multi-core strip until the coating on the surface is dissolved, and then use it to remove After washing 4 times with deionized water, soak in metal detergent for 30 minutes to remove the oil stain on the surface of the Bi-2212 superconducting multi-core strip. After the oil stain is removed, use deionized water to wash and remove the oil. Dehydrated with alcohol and dried;

Step 3, placing the Bi-2212 superconducting multi-core strip dried in Step 2 in a vacuum furnace, and heat-treating it for 2 hours at a vacuum degree of 10 ⁻³ Pa and a temperature of 600° C.;

Step 4. Add the Bi-2212 superconducting multi-core strip after heat treatment in Step 3 to 250mL of concentrated nitric acid and heat it to 150°C until a brown jelly is obtained, then add 250mL of concentrated nitric acid and heat to Keep warm at 200°C until dark brown jelly is obtained, then add 2500mL of distilled water and stir evenly, and finally leave it for 10 hours to obtain a precipitate;

Step 5, use a glass funnel covered with filter paper and filter cloth to filter the precipitated solution obtained in step 4 to obtain a filter cake and filtrate, then rinse the filter cake with deionized water until the filter cake is neutral, collect and rinse The deionized water behind the filter cake is mixed with the filtrate to obtain a mixed solution;

Step 6. First heat the mixed solution mentioned in step 5 to 100°C, then add concentrated hydrochloric acid to the mixed solution for precipitation reaction, after the precipitation reaction is completed, age in the dark for 8 hours, and then use a cloth covered with two layers of filter paper Equation funnel carries out suction filtration, adopts deionized water to wash again to neutrality, obtains silver chloride filter cake; The mass concentration of described concentrated hydrochloric acid is 50%, and adding volume is 380mL;

Step 7, in the silver chloride filter cake that obtains in step 6, slowly add ammoniacal liquor dropwise, until silver chloride filter cake and ammoniacal liquor react completely, generate diammine silver chloride solution, then heat diammine silver chloride solution Remove excess ammonia water until boiling, and then slowly add hydrazine hydrate with a mass concentration of 50% to the silver diammine chloride solution under constant stirring to carry out the precipitation reaction until no more precipitates are generated. After the reaction was completed, the reaction solution was cooled, and finally filtered with a Buchner funnel, washed with deionized water, and dried at 60° C. to obtain silver sponge.

The mass purity of the silver sponge obtained by the recovery of this embodiment is 99.97%, wherein the mass content of impurities Sb, Fe, Mn, Mg, Pb, Sn, Au, Al, Ca, Ir, Rh, Pt, Pd, Sr is all less than 0.001 %, the mass content of impurities Ni and Si is 0.001%, the mass content of impurity Cu is 0.002%, the mass content of impurity Bi is less than 0.0003%, and the mass content of Zr is less than 0.002%.

Example 4

The method that present embodiment reclaims Ag comprises the following steps:

Step 1. Shorten 500 grams of Bi-2223 single-core superconducting tape with sterling silver sheath;

Step 2. First mix the concentrated ammonia water with a mass concentration of 25% and deionized water at a volume ratio of 1:10, and then use it to soak the Bi-2223 single-core superconducting tape until the coating on the surface is dissolved, and then use it to remove After washing 4 times with deionized water, soak in metal detergent for 30 minutes to remove the oil stain on the surface of the Bi-2223 single-core superconducting strip. After the oil stain is removed, use deionized water to wash the Bi-2223 single-core superconducting strip. Dehydrated with alcohol and dried;

Step 3, placing the Bi-2223 single-core superconducting strip dried in step 2 in a vacuum furnace, and heat-treating it for 4 hours at a vacuum degree of 10 ⁻³ Pa and a temperature of 400° C.;

Step 4. Add the Bi-2223 single-core superconducting tape after the heat treatment in Step 3 to 250mL of concentrated nitric acid and heat it to 150°C until a brown jelly is obtained, then add 250mL of concentrated nitric acid and heat to Keep warm at 160°C until dark brown jelly is obtained, then add 2500mL of distilled water and stir evenly, and finally leave it for 8 hours to obtain a precipitate;

Step 5, use a glass funnel covered with filter paper and filter cloth to filter the precipitated solution obtained in step 4 to obtain a filter cake and filtrate, then rinse the filter cake with deionized water until the filter cake is neutral, collect and rinse The deionized water behind the filter cake is mixed with the filtrate to obtain a mixed solution;

Step 6. First heat the mixed solution described in step 5 to 80°C, then add concentrated hydrochloric acid to the mixed solution for precipitation reaction, after the precipitation reaction is completed, age in the dark for 5 hours, and then use a cloth covered with two layers of filter paper Equation funnel carries out suction filtration, adopts deionized water to wash again to neutrality, obtains silver chloride filter cake; The mass concentration of described concentrated hydrochloric acid is 50%, and adding volume is 350mL;

Step 7, in the silver chloride filter cake that obtains in step 6, slowly add ammoniacal liquor dropwise, until silver chloride filter cake and ammoniacal liquor react completely, generate diammine silver chloride solution, then heat diammine silver chloride solution Remove excess ammonia water until boiling, and then slowly add hydrazine hydrate with a mass concentration of 50% to the silver diammine chloride solution under constant stirring to carry out the precipitation reaction until no more precipitates are generated. After the reaction was completed, the reaction solution was cooled, and finally filtered with a Buchner funnel, washed with deionized water, and dried at 60° C. to obtain silver sponge.

The mass purity of the sponge silver that the present embodiment reclaims is 99.98%, wherein the mass content of impurity Sb, Fe, Mn, Mg, Pb, Sn, Au, Al, Ca, Ir, Rh, Pt, Pd, Zr, Sr Less than 0.001%, the mass content of impurities Ni, Si and Cu is 0.001%, and the mass content of impurity Bi is less than 0.0003%.

Example 5

The method that present embodiment reclaims Ag comprises the following steps:

Step 1, cut short the Bi-2223 multi-core superconducting wire that contains the silver-magnesium alloy sheath of 250 grams and the Bi-2223 multi-core superconducting strip that contains the silver-magnesium alloy sheath of 250 grams, obtains the multi-core superconducting strip that mixes wire strip;

Step 2. First mix the concentrated ammonia water with a mass concentration of 25% and deionized water at a volume ratio of 1:10, and then use it to soak the mixed multi-core superconducting wire strip until the coating on the surface is dissolved, and then use deionized water After washing with water for 4 times, use metal detergent to soak for 30 minutes to remove the oil stain on the surface of the mixed multi-core superconducting wire strip. After the oil stain is removed, use deionized water to wash the mixed multi-core superconducting wire strip after removing the oil stain, and finally use alcohol to dehydrate. and dry;

Step 3, placing the mixed multi-core superconducting wire strips dried in step 2 in a vacuum furnace, and heat-treating for 3 hours under the conditions of a vacuum degree of 10 ⁻³ Pa and a temperature of 500° C.;

Step 4. Add the mixed multi-core superconducting wire strips after the heat treatment in step 3 to 250mL of concentrated nitric acid and heat to 155°C until a brown jelly is obtained, then add 250mL of concentrated nitric acid and heat to 180°C Keep warm at ℃ until a dark brown jelly is obtained, then add 2500mL of distilled water and stir evenly, and finally leave it for 9 hours to obtain a precipitate;

Step 5, use a glass funnel covered with filter paper and filter cloth to filter the precipitated solution obtained in step 4 to obtain a filter cake and filtrate, then rinse the filter cake with deionized water until the filter cake is neutral, collect and rinse The deionized water behind the filter cake is mixed with the filtrate to obtain a mixed solution;

Step 6. First heat the mixed solution described in step 5 to 90°C, then add concentrated hydrochloric acid to the mixed solution for precipitation reaction, after the precipitation reaction is completed, age in the dark for 7 hours, and then use a cloth covered with two layers of filter paper Equation funnel carries out suction filtration, adopts deionized water to wash again to neutrality, obtains silver chloride filter cake; The mass concentration of described concentrated hydrochloric acid is 50%, and adding volume is 380mL;

Step 7, in the silver chloride filter cake that obtains in step 6, slowly add ammoniacal liquor dropwise, until silver chloride filter cake and ammoniacal liquor react completely, generate diammine silver chloride solution, then heat diammine silver chloride solution Remove excess ammonia water until boiling, and then slowly add hydrazine hydrate with a mass concentration of 50% to the silver diammine chloride solution under constant stirring to carry out the precipitation reaction until no more precipitates are generated. After the reaction was completed, the reaction solution was cooled, and finally filtered with a Buchner funnel, washed with deionized water, and dried at 60° C. to obtain silver sponge.

The mass purity of the silver sponge obtained by the recovery of this embodiment is 99.97%, wherein the mass content of impurities Sb, Fe, Mn, Mg, Pb, Sn, Au, Al, Ca, Ir, Rh, Pt, Pd, Sr is all less than 0.001 %, the mass content of impurities Ni, Si and Cu is 0.001%, the mass content of impurities Bi is less than 0.0003%, and the mass content of Zr is less than 0.002%.

Example 6

The method that present embodiment reclaims Ag comprises the following steps:

Step 1, 200 grams of Bi-2223 multi-core superconducting tapes containing silver-gold sheath and 300 grams of Bi-2212 multi-core superconducting tapes are shortened to obtain mixed superconducting tapes;

Step 2. First mix the concentrated ammonia water with a mass concentration of 25% and deionized water at a volume ratio of 1:10, and then use it to soak the mixed superconducting strip until the coating on the surface is dissolved, and then wash it with deionized water After 4 times, use metal detergent to soak for 30 minutes to remove the oil stain on the surface of the mixed superconducting strip. After the oil stain is removed, use deionized water to wash the mixed superconducting strip after removing the oil stain, and finally use alcohol to dehydrate and dry;

Step 3, placing the mixed superconducting strips dried in step 2 in a vacuum furnace, and heat-treating them for 2 hours under the conditions of a vacuum degree of 10 ⁻³ Pa and a temperature of 600° C.;

Step 4. Add the mixed superconducting tape after heat treatment in step 3 to 250mL of concentrated nitric acid and heat to 155°C to keep it warm until a brown jelly is obtained, then add 250mL of concentrated nitric acid and heat to 200°C to keep it warm , until a dark brown jelly is obtained, add 2500mL of distilled water and stir evenly, and finally leave it for 10 hours to obtain a precipitate;

Step 5, use a glass funnel covered with filter paper and filter cloth to filter the precipitated solution obtained in step 4 to obtain a filter cake and filtrate, then rinse the filter cake with deionized water until the filter cake is neutral, collect and rinse The deionized water behind the filter cake is mixed with the filtrate to obtain a mixed solution;

Step 6. First heat the mixed solution mentioned in step 5 to 100°C, then add concentrated hydrochloric acid to the mixed solution for precipitation reaction, after the precipitation reaction is completed, age in the dark for 8 hours, and then use a cloth covered with two layers of filter paper Equation funnel carries out suction filtration, adopts deionized water to wash again to neutrality, obtains silver chloride filter cake; The mass concentration of described concentrated hydrochloric acid is 50%, and adding volume is 380mL;

Step 7, in the silver chloride filter cake that obtains in step 6, slowly add ammoniacal liquor dropwise, until silver chloride filter cake and ammoniacal liquor react completely, generate diammine silver chloride solution, then heat diammine silver chloride solution Remove excess ammonia water until boiling, and then slowly add hydrazine hydrate with a mass concentration of 50% to the silver diammine chloride solution under constant stirring to carry out the precipitation reaction until no more precipitates are generated. After the reaction was completed, the reaction solution was cooled, and finally filtered with a Buchner funnel, washed with deionized water, and dried at 60° C. to obtain silver sponge.

The mass purity of the sponge silver recovered in this embodiment is 99.96%, wherein the mass content of impurities Sb, Fe, Mn, Mg, Pb, Sn, Au, Al, Ca, Ir, Rh, Pt, Pd, Sr is all less than 0.001 %, the mass content of impurities Ni, Si and Cu is 0.001%, the mass content of impurities Bi is less than 0.0003%, and the mass content of Zr is less than 0.002%.

Example 7

The method that present embodiment reclaims Ag comprises the following steps:

Step 1. Shorten 500 grams of Bi-2223 single-core superconducting wire with sterling silver sheath;

Step 2. First mix the concentrated ammonia water with a mass concentration of 25% and deionized water at a volume ratio of 1:10, and then use it to soak the Bi-2223 single-core superconducting wire until the coating on the surface is dissolved, and then use deionized After washing with water for 4 times, soak in metal detergent for 30 minutes to remove the oil on the surface of the Bi-2223 single-core superconducting wire. After the oil is removed, use deionized water to wash the Bi-2223 single-core superconducting wire after removing the oil, and finally use alcohol to dehydrate. and dry;

Step 3, placing the Bi-2223 single-core superconducting wire dried in step 2 in a vacuum furnace, and heat-treating for 4 hours under the conditions of a vacuum degree of 10 ⁻³ Pa and a temperature of 400° C.;

Step 4. Add the Bi-2223 single-core superconducting wire after the heat treatment in Step 3 to 250mL of concentrated nitric acid and heat it to 153°C until a brown jelly is obtained, then add 250mL of concentrated nitric acid and heat to 160°C Keep warm at ℃ until dark brown jelly is obtained, then add 2500mL of distilled water and stir evenly, and finally leave it for 8 hours to obtain a precipitate;

Step 5, use a glass funnel covered with filter paper and filter cloth to filter the precipitated solution obtained in step 4 to obtain a filter cake and filtrate, then rinse the filter cake with deionized water until the filter cake is neutral, collect and rinse The deionized water behind the filter cake is mixed with the filtrate to obtain a mixed solution;

Step 6. First heat the mixed solution described in step 5 to 80°C, then add concentrated hydrochloric acid to the mixed solution for precipitation reaction, after the precipitation reaction is completed, age in the dark for 5 hours, and then use a cloth covered with two layers of filter paper Equation funnel carries out suction filtration, adopts deionized water to wash again to neutrality, obtains silver chloride filter cake; The mass concentration of described concentrated hydrochloric acid is 50%, and adding volume is 400mL;

Step 7, in the silver chloride filter cake that obtains in step 6, slowly add ammoniacal liquor dropwise, until silver chloride filter cake and ammoniacal liquor react completely, generate diammine silver chloride solution, then heat diammine silver chloride solution Remove excess ammonia water until boiling, and then slowly add hydrazine hydrate with a mass concentration of 50% to the silver diammine chloride solution under constant stirring to carry out the precipitation reaction until no more precipitates are generated. After the reaction was completed, the reaction solution was cooled, and finally filtered with a Buchner funnel, washed with deionized water, and dried at 60° C. to obtain silver sponge.

The quality purity of the sponge silver that the present embodiment reclaims is 99.99%, wherein the quality of impurity Sb, Fe, Mn, Mg, Pb, Sn, Au, Al, Ca, Ir, Rh, Pt, Pd, Zr, Sr, Si The contents are all less than 0.001%, the mass content of impurities Ni and Cu is 0.001%, and the mass content of impurity Bi is less than 0.0003%.

Comparative example 1

The difference between the recovery method of Ag in this comparative example and Example 7 lies in: step 4, add the Bi-based superconducting wire rod after the heat treatment in step 3 to 500mL of concentrated nitric acid and heat it to 160°C until the dark brown glue is obtained. Add 2500mL of distilled water and stir evenly, and finally leave it for 8 hours to obtain a precipitate; the rest of the steps are the same as the corresponding steps in Example 7.

This comparative example adopts the method of one-step acidolysis recovery line strip in step 4, and its characteristic is that the temperature of each element is too high when the acidolysis starts to react, and it is easy to splash, and after the end of the acidolysis, Bi is easily hydrolyzed due to the change of acidity. The content is higher (spectral analysis Bi 0.1%), while the recovery and purity are reduced. In addition, there is no step 3 in the comparative example. Step 3 of the present invention can remove the vulcanized layer on the surface of the incoming material sheath and the water vapor absorbed in the washing process of step 2. Therefore, except that step 3 and step 4 are different, the remaining steps of the comparative example are the same as This example is the same:

Example 8

The method that present embodiment reclaims Ag comprises the following steps:

Step 1, shorten 500 grams of Bi-2223 multi-core superconducting wire with a silver-magnesium alloy sheath;

Step 2. First mix the concentrated ammonia water with a mass concentration of 25% and deionized water at a volume ratio of 1:10, and then use it to soak the Bi-2223 multi-core superconducting wire until the coating on the surface is dissolved, and then use deionized After washing with water for 4 times, soak in metal detergent for 30 minutes to remove the oil on the surface of the Bi-2223 multi-core superconducting wire. After the oil is removed, use deionized water to wash the Bi-2223 multi-core superconducting wire after degreasing, and finally use alcohol to dehydrate. and dry;

Step 3, placing the Bi-2223 multi-core superconducting wire dried in Step 2 in a vacuum furnace, and heat-treating for 3 hours under the conditions of a vacuum degree of 10 ⁻³ Pa and a temperature of 500° C.;

Step 4. Add the Bi-2223 multi-core superconducting wire after the heat treatment in step 3 to 250mL of concentrated nitric acid and heat it to 150°C until a brown jelly is obtained, then add 250mL of concentrated nitric acid and heat to 180°C Keep warm at ℃ until a dark brown jelly is obtained, then add 2500mL of distilled water and stir evenly, and finally leave it for 9 hours to obtain a precipitate;

Step 5, use a glass funnel covered with filter paper and filter cloth to filter the precipitated solution obtained in step 4 to obtain a filter cake and filtrate, then rinse the filter cake with deionized water until the filter cake is neutral, collect and rinse The deionized water behind the filter cake is mixed with the filtrate to obtain a mixed solution;

Step 6. First heat the mixed solution described in step 5 to 90°C, then add concentrated hydrochloric acid to the mixed solution for precipitation reaction, after the precipitation reaction is completed, age in the dark for 7 hours, and then use a cloth covered with two layers of filter paper Equation funnel carries out suction filtration, adopts deionized water to wash again to neutrality, obtains silver chloride filter cake; The mass concentration of described concentrated hydrochloric acid is 50%, and adding volume is 350mL;

Step 7, in the silver chloride filter cake that obtains in step 6, slowly add ammoniacal liquor dropwise, until silver chloride filter cake and ammoniacal liquor react completely, generate diammine silver chloride solution, then heat diammine silver chloride solution Remove excess ammonia water until boiling, and then slowly add hydrazine hydrate with a mass concentration of 50% to the silver diammine chloride solution under constant stirring to carry out the precipitation reaction until no more precipitates are generated. After the reaction was completed, the reaction solution was cooled, and finally filtered with a Buchner funnel, washed with deionized water, and dried at 60° C. to obtain silver sponge.

The mass purity of the sponge silver that the present embodiment reclaims is 99.98%, wherein the mass content of impurity Sb, Fe, Mn, Mg, Pb, Sn, Au, Al, Ca, Ir, Rh, Pt, Pd, Zr, Sr Less than 0.001%, the mass content of impurities Ni, Si and Cu is 0.001%, and the mass content of impurity Bi is less than 0.0003%.

Example 9

The method that present embodiment reclaims Ag comprises the following steps:

Step 1, 100 grams of Bi-2223 multi-core superconducting strips containing silver-gold sheath and 400 grams of Bi-2212 multi-core superconducting strips are shortened to obtain mixed multi-core superconducting strips;

Step 2. First mix the concentrated ammonia water with a mass concentration of 25% and deionized water at a volume ratio of 1:10, and then use it to soak the mixed multi-core superconducting strip until the coating on the surface is dissolved, and then use deionized After washing with water for 4 times, use metal detergent to soak for 30 minutes to remove the oil stain on the surface of the mixed multi-core superconducting strip. After the oil stain is removed, use deionized water to wash the mixed multi-core superconducting strip after removing the oil stain, and finally use alcohol to dehydrate. and dry;

Step 3, placing the mixed multi-core ^{superconducting} strips dried in step 2 in a vacuum furnace, and heat-treating for 3 hours under the conditions of a vacuum degree of 10 ⁻³ Pa and a temperature of 600° C.;

Step 4. Add the mixed multi-core superconducting tape after heat treatment in step 3 to 250mL of concentrated nitric acid and heat it to 150°C until a brown jelly is obtained, then add 250mL of concentrated nitric acid and heat to 200°C Keep warm at ℃ until dark brown jelly is obtained, add 2500mL of distilled water and stir evenly, and finally leave it for 10 hours to obtain a precipitate;

Step 5, use a glass funnel covered with filter paper and filter cloth to filter the precipitated solution obtained in step 4 to obtain a filter cake and filtrate, then rinse the filter cake with deionized water until the filter cake is neutral, collect and rinse The deionized water behind the filter cake is mixed with the filtrate to obtain a mixed solution;

Step 6. First heat the mixed solution mentioned in step 5 to 100°C, then add concentrated hydrochloric acid to the mixed solution for precipitation reaction, after the precipitation reaction is completed, age in the dark for 8 hours, and then use a cloth covered with two layers of filter paper Equation funnel carries out suction filtration, adopts deionized water to wash again to neutrality, obtains silver chloride filter cake; The mass concentration of described concentrated hydrochloric acid is 50%, and adding volume is 380mL;

Step 7, in the silver chloride filter cake that obtains in step 6, slowly add ammoniacal liquor dropwise, until silver chloride filter cake and ammoniacal liquor react completely, generate diammine silver chloride solution, then heat diammine silver chloride solution Remove excess ammonia water until boiling, and then slowly add hydrazine hydrate with a mass concentration of 50% to the silver diammine chloride solution under constant stirring to carry out the precipitation reaction until no more precipitates are generated. After the reaction was completed, the reaction solution was cooled, and finally filtered with a Buchner funnel, washed with deionized water, and dried at 60° C. to obtain silver sponge.

The mass purity of the silver sponge obtained by the recovery of this embodiment is 99.97%, wherein the mass content of impurities Sb, Fe, Mn, Mg, Pb, Sn, Au, Al, Ca, Ir, Rh, Pt, Pd, Sr is all less than 0.001 %, the mass content of impurities Ni, Si and Cu is 0.001%, the mass content of impurities Bi is less than 0.0003%, and the mass content of Zr is less than 0.002%.

Example 10

The method that present embodiment reclaims Ag comprises the following steps:

Step 1, 300 grams of Bi-2223 single-core superconducting tape containing silver-magnesium alloy sheath, 100 grams of Bi-2223 single-core superconducting tape containing silver-gold alloy and 100 grams of Bi-2223 single-core superconducting tape containing pure silver sheathing -2223 single-core superconducting strips are shortened to obtain mixed Bi-2223 single-core superconducting strips;

Step 2. First mix the concentrated ammonia water with a mass concentration of 25% and deionized water at a volume ratio of 1:10, and then use it to soak the mixed Bi-2223 single-core superconducting tape until the coating on the surface is dissolved, and then After washing 4 times with deionized water, use metal detergent to soak for 30 minutes to remove the oil stain on the surface of the mixed Bi-2223 single-core superconducting strip. After the oil stain is removed, use deionized water to wash and remove the mixed Bi-2223 single core Superconducting tape, finally dehydrated with alcohol and dried;

Step 3, placing the mixed Bi-2223 single-core superconducting strips dried and mixed in Step 2 in a vacuum furnace, and heat-treating for 3 hours at a vacuum degree of 10 ⁻³ Pa and a temperature of 600° C.;

Step 4. Add the mixed Bi-2223 single-core superconducting tape after the heat treatment in Step 3 to 250mL of concentrated nitric acid and heat it to 155°C until a brown jelly is obtained, then add 250mL of concentrated nitric acid and Heat to 200°C and keep warm until a dark brown jelly is obtained, then add 2500mL of distilled water and stir evenly, and finally leave it for 10 hours to obtain a precipitate;

Step 5, use a glass funnel covered with filter paper and filter cloth to filter the precipitated solution obtained in step 4 to obtain a filter cake and filtrate, then rinse the filter cake with deionized water until the filter cake is neutral, collect and rinse The deionized water behind the filter cake is mixed with the filtrate to obtain a mixed solution;

Step 6. First heat the mixed solution mentioned in step 5 to 100°C, then add concentrated hydrochloric acid to the mixed solution for precipitation reaction, after the precipitation reaction is completed, age in the dark for 8 hours, and then use a cloth covered with two layers of filter paper Equation funnel carries out suction filtration, adopts deionized water to wash again to neutrality, obtains silver chloride filter cake; The mass concentration of described concentrated hydrochloric acid is 50%, and adding volume is 380mL;

Step 7, in the silver chloride filter cake that obtains in step 6, slowly add ammoniacal liquor dropwise, until silver chloride filter cake and ammoniacal liquor react completely, generate diammine silver chloride solution, then heat diammine silver chloride solution Remove excess ammonia water until boiling, and then slowly add hydrazine hydrate with a mass concentration of 50% to the silver diammine chloride solution under constant stirring to carry out the precipitation reaction until no more precipitates are generated. After the reaction was completed, the reaction solution was cooled, and finally filtered with a Buchner funnel, washed with deionized water, and dried at 60° C. to obtain silver sponge.

The mass purity of the sponge silver that the present embodiment reclaims is 99.98%, wherein the mass content of impurity Sb, Fe, Mn, Mg, Pb, Sn, Au, Al, Ca, Ir, Rh, Pt, Pd, Zr, Sr Less than 0.001%, the mass content of impurities Ni, Si and Cu is 0.001%, and the mass content of impurity Bi is less than 0.0003%.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any way. All simple modifications, changes and equivalent changes made to the above embodiments according to the technical essence of the invention still belong to the protection scope of the technical solution of the invention.

Claims (7)

1. the recovery method of Ag in a kind of Bi systems superconducting line strips, it is characterized in that, which includes the following steps：

Step 1: cutting short Bi systems superconducting line strips, Bi systems superconducting line strips are argentiferous jacket or the single of silver alloy jacket Or multicore Bi systems superconducting line strips；

Step 2: Bi systems superconducting line strips face coat and greasy dirt after being cut short in step 1 are first removed, then using deionized water The Bi systems superconducting line strips after degreasing are cleaned, finally using dehydration of alcohol and are dried；

It is 10 in vacuum degree Step 3: the Bi systems superconducting line strips after being dried in step 2 are placed in vacuum drying oven^-3Pa, temperature 2h~4h is heat-treated under conditions of being 400 DEG C~600 DEG C；

Step 4: the Bi systems superconducting line strips after being heat-treated in step 3 are added in concentrated nitric acid and are heated to 150 DEG C~155 DEG C Heat preservation, until obtaining yellow gum object, then adding concentrated nitric acid and being heated to 160 DEG C~200 DEG C heat preservations, until obtaining dark brown Color jelly, then distilled water is added to stir evenly, 8h~10h is placed in finally ageing, obtains precipitated liquid；

Step 5: being filtered to the precipitated liquid obtained in step 4, filter cake and filtrate are obtained, is then rinsed using deionized water The filter cake until filter cake is in neutrality, is collected the deionized water after rinsing filter cake and is mixed with the filtrate, obtain mixed liquor；

Step 6: mixed liquor described in first heating stepses five is to 80 DEG C~100 DEG C, then add in into the mixed liquor concentrated hydrochloric acid into Row precipitation reaction is protected from light ageing 5h~8h, is then filtered and washs, obtain silver chlorate filter cake after the completion of reaction to be precipitated, The silver chlorate filter cake is in neutrality；

Step 7: ammonium hydroxide is slowly added dropwise in the silver chlorate filter cake obtained into step 6, until silver chlorate filter cake and ammonium hydroxide are complete Reaction generates two ammino silver solution of chlorination, then heats two ammino silver solution of chlorination and removes extra ammonium hydroxide, then not to boiling Hydrazine hydrate is slowly added dropwise into two ammino silver solution of chlorination under conditions of disconnected stirring and carries out precipitation reaction, until there is no sediments Until generation, postcooling reaction solution is completed in reaction to be precipitated, it is last it is filtered, wash and be dried to obtain sponge silver.

2. the recovery method of Ag in a kind of Bi systems superconducting line strips according to claim 1, it is characterized in that：Described in step 1 Bi systems superconducting line strips are Bi-2223 superconducting line strips or Bi-2212 superconducting line strips.

3. the recovery method of Ag in a kind of Bi systems superconducting line strips according to claim 1, it is characterized in that：Step 2 removes The detailed process of Bi systems superconducting line strips face coat and greasy dirt after being cut short in step 1 is：First by mass concentration for 22%~ 25% concentrated ammonia liquor and deionized water presses 1：10 volume ratio is uniformly mixed, and is used further to impregnate Bi system's superconducting line strips until surface Coating dissolving, then be washed with deionized 4 times, 30min finally impregnated using metal detergent and removes Bi systems superconducting line strips The greasy dirt on surface.

4. the recovery method of Ag in a kind of Bi systems superconducting line strips according to claim 1, it is characterized in that：Two in step 4 The total volume of the concentrated nitric acid of secondary addition is 1 times of the quality of Bi systems superconducting line strips, adds in the volume of the deionized water The unit of 5 times of quality for Bi systems superconducting line strips, the total volume of the concentrated nitric acid and the volume of deionized water is ML, the unit of the quality of Bi systems superconducting line strips is g, and the mass concentration of the concentrated nitric acid is 68%.

5. the recovery method of Ag in a kind of Bi systems superconducting line strips according to claim 1, it is characterized in that：Mistake in step 5 Using the glass funnel for being covered with filter paper and filter cloth during filter, using the cloth funnel for being covered with two layers of filter paper when being filtered in step 6.

6. the recovery method of Ag in a kind of Bi systems superconducting line strips according to claim 1, it is characterized in that：Institute in step 6 The dosage for stating concentrated hydrochloric acid adds in the concentrated hydrochloric acid of 350mL~400mL, institute for Bi systems superconducting line strips described in every 500 grams of step 1 The mass concentration for stating concentrated hydrochloric acid is 50%.

7. the recovery method of Ag in a kind of Bi systems superconducting line strips according to claim 1, it is characterized in that：Institute in step 7 The mass concentration for stating hydrazine hydrate is 50%~80%, the temperature 60 C of the drying.