A method for separating Cu, Ag, and Sn-Pb / Sn-Bi coatings from waste photovoltaic ribbons

Abstract

The invention relates to a method for separating Cu, Ag and Sn-Pb / Sn-Bi coatings in waste photovoltaic welding ribbons, belonging to the technical field of photovoltaic solid waste recycling. The invention places waste photovoltaic welding ribbons in a supergravity separation device, heats the waste photovoltaic welding ribbons in an inert atmosphere to completely melt a Sn-X coating containing Ag on the surface thereof, keeps a Cu ribbon inside the waste photovoltaic welding ribbons in a solid phase, and performs supergravity melting separation in a centrifugal device to obtain a Sn-X-Ag coating melt and a solid-phase Cu ribbon, wherein X is Pb or Bi; adds metallic Mg to the Sn-X-Ag melt, obtains a Sn-X-Ag-Mg melt after Mg is completely dissolved, uniformly cools the melt to a preset melt coagulation temperature under stirring, causes the Sn-X-Ag-Mg melt to coagulate, obtains a mixture of a solid-phase Ag-Mg compound and a Sn-X melt, performs supergravity coagulation separation in a centrifugal device, obtains a solid-phase Ag-Mg compound and a Sn-X alloy melt; and heats the Ag-Mg alloy to a temperature of 950-1050° C. under vacuum conditions, performs vacuum distillation, realizes Ag-Mg alloy separation, obtains metallic Ag and metallic Mg, and the metallic Mg can be returned for recycling. The produced Sn-Pb, Sn-Bi alloy and metallic Cu are recycled into new photovoltaic ribbons.

Description

Technical Field

[0001] The invention relates to a method for separating Cu, Ag and Sn-Pb / Sn-Bi coatings in waste photovoltaic welding ribbons, belonging to the technical field of photovoltaic solid waste recycling. Background Art

[0002] Waste photovoltaic welding ribbons contain valuable metals such as Ag, Cu, Sn, Pb and Bi. Recycling these valuable metals greatly reduces resource waste, realizes secondary utilization of resources, and has higher economic value.

[0003] Currently, the primary method for recovering valuable metals from scrap photovoltaic ribbons is hydrometallurgical processes. For example, the scrap photovoltaic ribbon is dissolved in HNO₃, then HCl solution is added to precipitate Ag to produce an AgCl precipitate. For Cu in the solution, LIX84-I is used to extract Cu from the leachate to obtain a Cu-containing organic phase. H₂SO₄ is then added for Cu stripping to produce a CuSO₄ solution. Finally, the CuSO₄ solution is subjected to electrolysis to obtain metallic Cu in the Sn solution. The Sn-containing organic phase is extracted using TBP and stripped with HNO₃ to produce Sn(NO₃)₄. Finally, NH₄OH precipitation and calcination are performed to obtain SnO₂. For Pb in the solution, NaOH precipitation and calcination are also required to obtain PbO. Therefore, the use of hydrometallurgical processes to recover valuable metals from scrap solar cells is not only complex but also requires a large amount of chemical reagents, making waste gas and liquid treatment more difficult and adversely impacting the environment. Summary of the Invention

[0004] Aiming at the problems of complex process and large amount of waste liquid discharge in the existing hydrometallurgical process for recycling valuable metals in waste photovoltaic welding ribbons, the present invention provides a method for separating Cu, Ag and Sn-Pb / Sn-Bi coatings in waste photovoltaic welding ribbons; the Cu in the welding ribbon and the silver-containing Sn-Pb / Sn-Bi coating are melted and separated by using the difference in melting points (the melting point of Cu is 1083.4°C, and the melting point of the coating is only 150-183°C), and combined with ultra-gravity technology, the centrifugal force is used to achieve the enhanced separation of solid-phase Cu and Sn-Pb-Ag / Sn-Bi-Ag melt; Sn and Ag are difficult to separate by vacuum distillation due to their similar vapor pressures (800-1300°C, with the vapor pressure difference of the two being only one order of magnitude). Therefore, Mg (Mg and Ag have a strong affinity) is added to the Sn-Pb-Ag / Sn-Bi-Ag melt, so that Ag will combine with Mg to form an Ag-Mg compound (condensation) with low density and insoluble in the melt, and the solid-phase Ag-Mg compound and the Sn-Pb / Sn-Bi melt are separated again by supergravity technology. The produced metal Cu and Sn-Pb / Sn-Bi alloy can be used to produce new photovoltaic welding ribbons for recycling; the separated Ag-Mg compound can be separated by vacuum distillation to obtain metal Ag and metal Mg due to the large difference in vapor pressure between Mg and Ag (in the range of 700-1000°C, the vapor pressure difference is 5-6 orders of magnitude), and the metal Mg can be recycled. The entire process of the present invention adopts physical methods to achieve green and efficient separation of valuable metals in waste photovoltaic welding ribbons.

[0005] A method for separating Cu, Ag, and Sn-Pb / Sn-Bi coatings from waste photovoltaic ribbons, comprising the following steps:

[0006] (1) placing waste photovoltaic ribbons in a high-gravity separation device, heating them under an inert atmosphere to completely melt the Ag-containing Sn-X coating on the surface of the waste photovoltaic ribbons, while the internal Cu ribbons remain in a solid phase, and performing high-gravity melting separation in a centrifugal device to obtain a Sn-X-Ag coating melt and a solid Cu ribbon; wherein X is Pb or Bi;

[0007] (2) adding metallic Mg to a Sn-X-Ag melt, and obtaining a Sn-X-Ag-Mg melt after Mg is completely dissolved; uniformly cooling the melt to a preset melt coagulation temperature under stirring conditions to allow the Sn-X-Ag-Mg melt to coagulate to obtain a mixture of a solid-phase Ag-Mg compound and a Sn-X melt; and performing ultra-gravity coagulation separation in a centrifugal device to obtain a solid-phase Ag-Mg compound and a Sn-X alloy melt;

[0008] (3) The Ag-Mg alloy is heated to a temperature of 950-1050° C. under vacuum conditions and vacuum distilled to separate the Ag-Mg alloy to obtain metallic Ag and metallic Mg, which is then returned to step (2) for recycling.

[0009] Preferably, the heating temperature in step (1) is 250-550° C., and the high gravity coefficient is 600-1000G.

[0010] Preferably, the amount of metal Mg added in step (2) is 6 to 10 wt% of the Sn-Pb-Ag / Sn-Bi-Ag melt.

[0011] Preferably, in step (2), when the Sn-X-Ag-Mg melt is a Sn-Pb-Ag-Mg melt, the coagulation temperature of the Sn-Pb-Ag-Mg melt is 250°C to 300°C, and the cooling rate is 2 to 4°C / min; when the Sn-X-Ag-Mg melt is a Sn-Bi-Ag-Mg melt, the coagulation temperature of the Sn-Bi-Ag-Mg melt is 280°C to 310°C, and the cooling rate is 1 to 3°C / min.

[0012] Preferably, the supergravity coefficient in step (2) is 500-700G.

[0013] The beneficial effects of the present invention are:

[0014] (1) The present invention utilizes the difference in melting points, combines high gravity separation technology with condensation technology, and realizes the efficient separation of valuable metals in waste photovoltaic welding ribbons, significantly improving the metal recovery rate;

[0015] (2) Compared with the traditional hydrometallurgical recovery process, the present invention reduces the treatment of waste liquid and waste gas, simplifies the process flow, and effectively reduces costs;

[0016] (3) The Sn-Pb / Sn-Bi alloy and metal Cu produced by the present invention can be used to produce new photovoltaic welding ribbons, and the metal Mg obtained by vacuum distillation separation can be recycled in the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a process flow chart of the present invention;

[0018] Figure 2 This is the EPMA-Mapping analysis diagram of the waste photovoltaic ribbon structure;

[0019] Figure 3 This is the effect of temperature on the composition of Sn-Pb-Ag melt during high-gravity melting separation;

[0020] Figure 4 This is the effect of temperature on the composition of Sn-Bi-Ag melt during high-gravity melting separation;

[0021] Figure 5 The effect of different gravity coefficients on the Ag recovery rate of photovoltaic ribbons;

[0022] Figure 6 The effect of different gravity coefficients on the purity of Cu substrate of photovoltaic ribbon;

[0023] Figure 7 The graph shows the change in the purity of Ag and Mg in the solid phase Ag-Mg compound at different vacuum distillation temperatures. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0025] Example 1: A method for separating Cu, Ag, and Sn-Pb / Sn-Bi coatings from waste photovoltaic ribbons (see Figure 1 ), the specific steps are as follows:

[0026] (1) The waste photovoltaic ribbon was placed in a high-gravity separation device and heated to a temperature of 250-550 °C in an inert (argon) atmosphere and kept warm for 30 min to completely melt the Ag-containing Sn-X (Sn-X is Sn-Pb or Sn-Bi) coating on the surface of the waste photovoltaic ribbon, while the internal Cu ribbon remained in the solid phase. The Sn-X-Ag (Sn-X-Ag is Sn-Pb-Ag or Sn-Bi-Ag) coating melt and the solid phase Cu ribbon were obtained by high-gravity melting separation (high-gravity coefficient of 600G) in a centrifugal device. The effect of temperature on the composition of Sn-Pb-Ag / Sn-Bi-Ag melt during the high-gravity melting separation process is shown in Figure 2. Figure 3 and 4 ; 250℃, 350℃, 450℃,

[0027] At 500℃ and 550℃, the Sn contents in the Sn-Pb-Ag melt are 51.2wt.%, 50.9wt.%, 50.7wt.%,

[0028] 50.4wt.%, 50.1wt.%, and Pb contents are 30.1wt.%, 29.7wt.%, 29.5wt.%, 29.1wt.%,

[0029] 28.9wt.%,Cu content is 0.2wt.%,0.6wt.%,0.9wt.%,1.3wt.%,1.5wt.%,Ag content is 16.5wt.%,16.8wt.%,16.9wt.%,17.2wt.%,17.5wt.%,(see Figure 3); the Sn contents in the Sn-Bi-Ag melt are 35.4wt.%, 35.2wt.%, 34.9wt.%, 34.6wt.%, and 34.1wt.%, respectively; the Bi contents are 45.8wt.%, 45.4wt.%, 45.1wt.%, 44.7wt.%, and 44.3wt.%, respectively; and the Cu contents are 0.4wt.%, 0.7wt.%, 0.9wt.%, and 0.8wt.%, respectively.

[0030] 1.3wt.%, 1.5wt.%, and the Ag content is 16.4wt.%, 16.6wt.%, 16.8wt.%, 16.9wt.%, and 17.1wt.% respectively (see Figure 4 );

[0031] (2) Taking the Sn-Pb-Ag melt and the Sn-Bi-Ag melt obtained by ultra-gravity melting separation at a temperature of 550°C as an example, metallic Mg (6 wt.% of the melt) is added to the Sn-X-Ag (Sn-X-Ag is Sn-Pb-Ag or Sn-Bi-Ag) melt at a temperature of 550°C, and after Mg is completely dissolved, a Sn-X-Ag-Mg melt (Sn-Pb-Ag-Mg melt or Sn-Bi-Ag-Mg melt) is obtained. The temperature is uniformly lowered to a preset melt coagulation temperature under stirring conditions to allow the Sn-X-Ag-Mg (Sn-Pb-Ag-Mg melt or Sn-Bi-Ag-Mg melt) melt to coagulate to obtain a mixture of a solid phase Ag-Mg compound and a Sn-X melt. Specifically, when the Sn-X-Ag-Mg melt is a Sn-Pb-Ag-Mg melt, the Sn-Pb-Ag-Mg melt is a Sn-Pb-Ag-Mg melt. The condensation temperature of the b-Ag-Mg melt is 250°C, and the cooling rate is 4°C / min. When the Sn-X-Ag-Mg melt is a Sn-Bi-Ag-Mg melt, the condensation temperature of the Sn-Bi-Ag-Mg melt is 280°C, and the cooling rate is 3°C / min. The solid phase Ag-Mg compound and the Sn-X (Sn-Pb or Sn-Bi) alloy melt are obtained by ultra-gravity condensation separation in a centrifugal device for 10 minutes (ultra-gravity coefficient is 600G). The Sn content of the Sn-Pb alloy is 57.7wt.%, the Pb content is 37.1wt.%, the Mg content is 2.0wt.%, and the Ag content is 1.5wt.%. The Sn content of the Sn-Bi melt is 37.3wt.%, the Bi content is 56.4wt.%, the Mg content is 1.9wt.%, and the Ag content is 1.4wt.%.

[0032] (3) The Ag-Mg alloy was heated to 1050° C. under vacuum (vacuum degree 40 Pa) and vacuum distilled for 30 min to separate the Ag-Mg alloy, thereby obtaining metallic Ag and metallic Mg (purity of 99.3 wt.%). The metallic Mg was returned to step (2) for recycling.

[0033] In this embodiment, the purity of the metal Ag is 97.8 wt.% (the main impurities are 0.7 wt.% Mg, 0.9 wt.% Sn, 0.05 wt.% Pb, and 0.5 wt.% Bi).

[0034] Example 2: A method for separating Cu, Ag, and Sn-Pb / Sn-Bi coatings from waste photovoltaic ribbons (see Figure 1 ), the specific steps are as follows:

[0035] (1) The waste photovoltaic ribbon was placed in a high-gravity separation device and heated to 450 °C in an inert (helium) atmosphere and kept warm for 35 min to completely melt the Ag-containing Sn-X (Sn-X is Sn-Pb or Sn-Bi) coating on the surface of the waste photovoltaic ribbon, while the internal Cu ribbon remained in the solid phase. The Sn-X-Ag (Sn-X-Ag is Sn-Pb-Ag or Sn-Bi-Ag) coating melt and the solid phase Cu ribbon were obtained by high-gravity melting separation in a centrifugal device (the high-gravity coefficients were 600G, 700G, 800G, 900G, and 1000G, respectively). At a temperature of 450 °C, the effect of the high-gravity coefficient on the Ag content in the melt and the Ag recovery rate is shown in Figure 2. Figure 5 ; 600G,

[0036] At 700G, 800G, 900G, and 1000G, the Ag content in the Sn-Pb-Ag melt is 16.8wt.%, 17.1wt.%, and

[0037] 17.2wt.%, 17.4wt.%, 17.6wt.%, and the average recovery rate of Ag was 92.8wt.%, 94.5wt.%, 95.1wt.%,

[0038] 96.1wt.%, 97.2wt.%; the Ag contents in Sn-Bi-Ag melt are 16.7wt.%, 16.9wt.%, 17.1wt.%,

[0039] 17.3wt.%, 17.4wt.%, and the average recovery rate of Ag was 93.8wt.%, 94.9wt.%, 95.5wt.%, 96.6wt.%,

[0040] 97.8wt.%; The effect of high gravity coefficient on Cu purity at 450℃ is shown in Figure 6 , 600G, 700G, 800G,

[0041] Under 900G and 1000G, the purity of the metal Cu separated from the Sn-Pb waste photovoltaic ribbon is 99.89wt.%,

[0042] The purity of the metallic Cu separated from the waste Sn-Bi photovoltaic ribbons was 99.91wt.%, 99.92wt.%, 99.93wt.%, and 99.94wt.%, respectively. The purity of the metallic Cu was 99.87wt.%, 99.89wt.%, 99.91wt.%, 99.92wt.%, and 99.93wt.%;

[0043] (2) Taking the Sn-Pb-Ag melt and the Sn-Bi-Ag melt obtained by ultra-gravity melting separation at an ultra-gravity coefficient of 1000G as an example, metallic Mg (7 wt.% of the melt) is added to the Sn-X-Ag (Sn-X-Ag is Sn-Pb-Ag or Sn-Bi-Ag) melt at a temperature of 575°C, and after Mg is completely dissolved, a Sn-X-Ag-Mg melt (Sn-Pb-Ag-Mg melt or Sn-Bi-Ag-Mg melt) is obtained. The temperature is uniformly lowered to a preset melt coagulation temperature under stirring conditions to allow the Sn-X-Ag-Mg (Sn-Pb-Ag-Mg melt or Sn-Bi-Ag-Mg melt) melt to coagulate to obtain a mixture of a solid phase Ag-Mg compound and a Sn-X melt. Specifically, when the Sn-X-Ag-Mg melt is a Sn-Pb-Ag-Mg melt, S The condensation temperature of the n-Pb-Ag-Mg melt is 250°C, and the cooling rate is 3°C / min. When the Sn-X-Ag-Mg melt is a Sn-Bi-Ag-Mg melt, the condensation temperature of the Sn-Bi-Ag-Mg melt is 280°C, and the cooling rate is 2°C / min. The solid phase Ag-Mg compound and the Sn-X (Sn-Pb or Sn-Bi) alloy melt are obtained by ultra-gravity condensation separation in a centrifugal device for 10 minutes (ultra-gravity coefficient is 500G). The Sn content in the Sn-Pb melt is 57.1wt.%, the Pb content is 36.5wt.%, the Mg content is 3.2wt.%, and the Ag content is 1.1wt.%. The Sn content in the Sn-Bi alloy is 36.7wt.%, the Bi content is 55.8wt.%, the Mg content is 3.3wt.%, and the Ag content is 1.2wt.%.

[0044] (3) The Ag-Mg alloy was heated to 950° C. under vacuum (vacuum degree 20 Pa) and vacuum distilled for 40 min to separate the Ag-Mg alloy, thereby obtaining metallic Ag and metallic Mg (purity of 98.9 wt.%). The metallic Mg was returned to step (2) for recycling.

[0045] In this embodiment, the purity of the metal Ag is 96.4 wt.% (the main impurities are 1.1 wt.% Mg, 1.2 wt.% Sn, 0.08 wt.% Pb, and 0.7 wt.% Bi).

[0046] Example 3: A method for separating Cu, Ag, and Sn-Pb / Sn-Bi coatings from waste photovoltaic ribbons (see Figure 1 ), the specific steps are as follows:

[0047] (1) The waste photovoltaic ribbon is placed in a supergravity separation device, heated to 500 ° C in an inert (argon) atmosphere and kept warm for 30 minutes to completely melt the Ag-containing Sn-X (Sn-X is Sn-Pb or Sn-Bi) coating on the surface of the waste photovoltaic ribbon, and the internal Cu ribbon remains in the solid phase. The supergravity melting separation (supergravity coefficient is 800G) of the Sn-X-Ag (Sn-X-Ag is Sn-Pb-Ag or Sn-Bi-Ag) coating melt and the solid phase are obtained by centrifugal device. Cu tape; the Sn content in the Sn-Pb-Ag melt is 50.7wt.%, the Pb content is 29.4wt.%, the Cu content is 1.5wt.%, the Ag content is 17.8wt.%, and the average Ag recovery rate is 98.3wt.%; the Sn content in the Sn-Bi-Ag melt is 35.1wt.%, the Pb content is 44.6wt.%, the Cu content is 1.4wt.%, the Ag content is 17.6wt.%, and the average Ag recovery rate is 97.8wt.%;

[0048] (2) adding metallic Mg (8 wt.% of the melt) to a Sn-X-Ag (Sn-X-Ag is Sn-Pb-Ag or Sn-Bi-Ag) melt at a temperature of 600°C, and obtaining a Sn-X-Ag-Mg melt (Sn-Pb-Ag-Mg melt or Sn-Bi-Ag-Mg melt) after Mg is completely dissolved, and uniformly cooling the melt to a preset melt coagulation temperature under stirring conditions to cause the Sn-X-Ag-Mg (Sn-Pb-Ag-Mg melt or Sn-Bi-Ag-Mg melt) melt to coagulate to obtain a mixture of a solid-phase Ag-Mg compound and a Sn-X melt. Specifically, when the Sn-X-Ag-Mg melt is a Sn-Pb-Ag-Mg melt, the coagulation temperature of the Sn-Pb-Ag-Mg melt is 300°C, and the temperature is lowered. The rate is 2°C / min; when the Sn-X-Ag-Mg melt is a Sn-Bi-Ag-Mg melt, the condensation temperature of the Sn-Bi-Ag-Mg melt is 310°C, and the cooling rate is 1°C / min; high-gravity condensation separation is performed by a centrifugal device for 5 minutes (high-gravity coefficient is 700G) to obtain a solid-phase Ag-Mg compound and a Sn-X (Sn-Pb or Sn-Bi) alloy melt; the Sn content of the Sn-Pb alloy is 56.2wt.%, the Pb content is 35.8wt.%, the Mg content is 4.2wt.%, and the Ag content is 0.93wt.%; the Sn content of the Sn-Bi alloy is 35.5wt.%, the Bi content is 56.6wt.%, the Mg content is 4.4wt.%, and the Ag content is 1.05wt.%;

[0049] (3) The Ag-Mg alloy was heated to 950° C. under vacuum (vacuum degree 10 Pa) and vacuum distilled for 30 min to separate the Ag-Mg alloy, thereby obtaining metallic Ag and metallic Mg (purity of 99.1 wt.%). The metallic Mg was returned to step (2) for recycling.

[0050] In this embodiment, the purity of the metal Ag is 96.6 wt.% (the main impurities are 0.9 wt.% Mg, 1.1 wt.% Sn, 0.07 wt.% Pb, and 0.84 wt.% Bi).

[0051] Example 4: A method for separating Cu, Ag, and Sn-Pb / Sn-Bi coatings from waste photovoltaic ribbons (see Figure 1 ), the specific steps are as follows:

[0052] (1) The waste photovoltaic ribbon is placed in a supergravity separation device, heated to 450 ° C in an inert (argon) atmosphere and kept warm for 40 minutes to completely melt the Ag-containing Sn-X (Sn-X is Sn-Pb or Sn-Bi) coating on the surface of the waste photovoltaic ribbon, and the internal Cu ribbon remains in the solid phase. The Sn-X-Ag (Sn-X-Ag is Sn-Pb-Ag or Sn-Bi-Ag) coating melt and solid phase are obtained by supergravity melting separation (supergravity coefficient is 900G) in a centrifugal device. Cu tape; the Sn content in the Sn-Pb-Ag melt is 50.3wt.%, the Pb content is 29.1wt.%, the Cu content is 1.4wt.%, the Ag content is 17.7wt.%, and the average Ag recovery rate is 97.8wt.%; the Sn content in the Sn-Bi-Ag melt is 34.9wt.%, the Pb content is 44.7wt.%, the Cu content is 1.5wt.%, the Ag content is 17.7wt.%, and the average Ag recovery rate is 98.2wt.%;

[0053] (2) adding metallic Mg (9 wt.% of the melt) to a Sn-X-Ag (Sn-X-Ag is Sn-Pb-Ag or Sn-Bi-Ag) melt at a temperature of 625°C, and obtaining a Sn-X-Ag-Mg melt (Sn-Pb-Ag-Mg melt or Sn-Bi-Ag-Mg melt) after Mg is completely dissolved, and uniformly cooling the melt to a preset melt coagulation temperature under stirring conditions to allow the Sn-X-Ag-Mg (Sn-Pb-Ag-Mg melt or Sn-Bi-Ag-Mg melt) melt to coagulate to obtain a mixture of a solid-phase Ag-Mg compound and a Sn-X melt. Specifically, when the Sn-X-Ag-Mg melt is a Sn-Pb-Ag-Mg melt, the Sn-Pb-Ag-Mg melt coagulation temperature is 280°C, and the cooling rate is 200°C. The Sn-X-Ag-Mg melt is a Sn-Bi-Ag-Mg melt, and the Sn-Bi-Ag-Mg melt coagulation temperature is 300°C, and the cooling rate is 2°C / min; the Sn-X-Ag-Mg melt is subjected to ultra-gravity coagulation separation in a centrifugal device for 15 minutes (the ultra-gravity coefficient is 700G) to obtain a solid phase Ag-Mg compound and a Sn-X (Sn-Pb or Sn-Bi) alloy melt; the Sn content in the Sn-Pb alloy is 55.9wt.%, the Pb content is 35.7wt.%, the Mg content is 5.1wt.%, and the Ag content is 0.95wt.%; the Sn content in the Sn-Bi alloy is 35.5wt.%, the Bi content is 56.6wt.%, the Mg content is 5.3wt.%, and the Ag content is 1.08wt.%;

[0054] (3) The Ag-Mg alloy is heated to a temperature of 950-1050° C. under vacuum (vacuum degree 15 Pa) and vacuum distilled for 40 min to separate the Ag-Mg alloy to obtain metallic Ag and metallic Mg, and the metallic Mg is returned to step (2) for recycling;

[0055] The changes of the purity of metal Mg and metal Ag with the distillation temperature in this example are shown in Figure 7 , 950℃, 970℃, 990℃,

[0056] At the distillation temperatures of 1010℃ and 1050℃, the purity of metallic Mg was 98.4wt.%, 98.7wt.%, 99.1wt.%,

[0057] 99.2wt.%, 99.3wt.%, and the purity of metal Ag is 96.2wt.%, 96.7wt.%, 97.1wt.%, 97.5wt.%,

[0058] 97.8wt.%.

[0059] Example 5: A method for separating Cu, Ag, and Sn-Pb / Sn-Bi coatings from waste photovoltaic ribbons (see Figure 1), the specific steps are as follows:

[0060] (1) The waste photovoltaic ribbon was placed in a supergravity separation device, heated to 550 ° C in an inert (argon) atmosphere and kept warm for 25 minutes to completely melt the Ag-containing Sn-X (Sn-X is Sn-Pb or Sn-Bi) coating on the surface of the waste photovoltaic ribbon, and the internal Cu ribbon remained in the solid phase. The Sn-X-Ag (Sn-X-Ag is Sn-Pb-Ag or Sn-Bi-Ag) coating melt and solid phase were obtained by supergravity melting separation (supergravity coefficient is 1000G) in a centrifugal device. Phase Cu belt; the Sn content in the Sn-Pb-Ag melt is 50.6wt.%, the Pb content is 29.6wt.%, the Cu content is 1.6wt.%, the Ag content is 17.8wt.%, and the average recovery rate of Ag is 98.4wt.%; the Sn content in the Sn-Bi-Ag melt is 35.3wt.%, the Pb content is 44.8wt.%, the Cu content is 1.4wt.%, the Ag content is 17.7wt.%, and the average recovery rate of Ag is 98.3wt.%;

[0061] (2) adding metallic Mg (10 wt.% of the melt) to a Sn-X-Ag (Sn-X-Ag is Sn-Pb-Ag or Sn-Bi-Ag) melt at a temperature of 650°C, and obtaining a Sn-X-Ag-Mg melt (Sn-Pb-Ag-Mg melt or Sn-Bi-Ag-Mg melt) after Mg is completely dissolved, and uniformly cooling the melt to a preset melt coagulation temperature under stirring to cause the Sn-X-Ag-Mg (Sn-Pb-Ag-Mg melt or Sn-Bi-Ag-Mg melt) melt to coagulate to obtain a mixture of a solid-phase Ag-Mg compound and a Sn-X melt. Specifically, when the Sn-X-Ag-Mg melt is a Sn-Pb-Ag-Mg melt, the coagulation temperature of the Sn-Pb-Ag-Mg melt is 270°C, and cooling the melt to a preset melt coagulation temperature. The rate is 2°C / min; when the Sn-X-Ag-Mg melt is a Sn-Bi-Ag-Mg melt, the condensation temperature of the Sn-Bi-Ag-Mg melt is 290°C, and the cooling rate is 1°C / min; high-gravity condensation separation is performed by a centrifugal device for 10 minutes (high-gravity coefficient is 600G) to obtain a solid-phase Ag-Mg compound and a Sn-X (Sn-Pb or Sn-Bi) alloy melt; the Sn content of the Sn-Pb alloy is 55.9wt.%, the Pb content is 35.7wt.%, the Mg content is 5.9wt.%, and the Ag content is 0.91wt.%; the Sn content of the Sn-Bi alloy is 35.5wt.%, the Bi content is 56.6wt.%, the Mg content is 5.8wt.%, and the Ag content is 0.96wt.%;

[0062] (3) The Ag-Mg alloy is heated to 1000° C. under vacuum (vacuum degree 30 Pa) and vacuum distilled for 35 min to separate the Ag-Mg alloy, thereby obtaining metallic Ag and metallic Mg (purity of 99.2 wt.%). The metallic Mg is returned to step (2) for recycling.

[0063] In this embodiment, the purity of the metal Ag is 97.7 wt.% (the main impurities are 0.7 wt.% Mg, 1.0 wt.% Sn, 0.06 wt.% Pb, and 0.65 wt.% Bi).

[0064] The above describes the specific embodiments of the present invention in detail, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope of the present invention.

Claims

1. A method for separating Cu, Ag, and Sn-Pb / Sn-Bi coatings from waste photovoltaic ribbons, characterized in that: The specific steps are as follows: (1) The waste photovoltaic ribbon is placed in a supergravity separation device, heated in an inert atmosphere to completely melt the Sn-X coating containing Ag on the surface of the waste photovoltaic ribbon, while the internal Cu ribbon remains in a solid phase, and supergravity melting separation is performed in a centrifugal device to obtain a Sn-X-Ag coating melt and a solid Cu ribbon; the X is Pb or Bi; the heating temperature is 250~550℃, and the supergravity coefficient is 600~1000G; (2) adding metallic Mg to the Sn-X-Ag melt, and obtaining the Sn-X-Ag-Mg melt after the Mg is completely dissolved; uniformly cooling the melt to a preset melt coagulation temperature under stirring conditions to allow the Sn-X-Ag-Mg melt to coagulate to obtain a mixture of a solid-phase Ag-Mg compound and a Sn-X melt; and performing ultra-gravity coagulation separation in a centrifugal device to obtain a solid-phase Ag-Mg compound and a Sn-X alloy melt; the Sn-X-Ag-Mg melt is a Sn-Pb-Ag-Mg melt. When the Sn-Pb-Ag-Mg melt is a Sn-Bi-Ag-Mg melt, the condensation temperature is 250°C~300°C, and the cooling rate is 2~4°C / min; when the Sn-X-Ag-Mg melt is a Sn-Bi-Ag-Mg melt, the condensation temperature of the Sn-Bi-Ag-Mg melt is 280°C~310°C, and the cooling rate is 1~3°C / min; the supergravity coefficient is 500~700G; the amount of metal Mg added is 6~10wt% of the Sn-Pb-Ag / Sn-Bi-Ag melt; (3) The Ag-Mg alloy is heated to a temperature of 950-1050°C under vacuum conditions and vacuum distilled to separate the Ag-Mg alloy to obtain metallic Ag and metallic Mg. The metallic Mg is returned to step (2) for recycling.

Images