Separation and recovery method for silver, copper and iron in silver, copper and iron composite waste

Abstract

The invention provides a method for separating and recycling silver, copper and iron in silver-copper-iron composite waste, and belongs to the technical field of metal composite waste separation and recycling. According to the method, the silver-copper-iron composite waste and the sulfuric acid solution are mixed and then subjected to the replacement reaction, iron and the silver-copper composite waste are separated, then the ferrous sulfate solution is crystallized, ferrous sulfate is obtained, and iron recycling is achieved; according to the method, the silver-copper composite waste is subjected to vacuum volatilization, by controlling the temperature of vacuum volatilization, silver can be volatilized to obtain silver steam and residual copper, separation and recovery of silver and copper are achieved, and the separation and recovery method is short in technological process, easy and convenient to operate, free of concentrated acid and environmentally friendly.

Description

Technical Field

[0001] The invention relates to the technical field of separation and recovery of metal composite waste, and in particular to a method for separating and recovering silver, copper and iron in silver-copper-iron composite waste. Background Art

[0002] Silver-copper-iron composite materials, composed of silver, copper, and iron, feature high electrical conductivity, high wear and corrosion resistance, low resistivity, good thermal conductivity, and excellent machinability, making them widely used in electronic devices and hardware tools. With the rapid development of electronics, electrical appliances, and communications, the production and use of silver-copper-iron composite materials inevitably generate increasing amounts of waste. Failure to recycle this waste not only wastes resources but also seriously pollutes the environment. Therefore, separating and recycling the silver, copper, and iron from this waste would yield significant environmental and economic benefits.

[0003] Currently, there are only a few technologies for the separation and recovery of silver-copper composite waste in the existing technology, and there is no technology related to the separation and recovery of silver-copper-iron composite waste. In addition, the separation and recovery of silver-copper composite waste in the existing technology generally uses a mixed solution of sodium chloride and concentrated nitric acid to dissolve copper and passivate silver to separate silver and copper, and then uses ammonia water to dissolve the surface of silver chloride to obtain silver solid and silver-ammonia mixed solution. The silver solid is electrolytically refined, and hydrazine hydrate is added to the silver-ammonia mixed solution to reduce it to form silver powder. This method uses a large amount of concentrated nitric acid when separating copper, generating a large amount of nitrogen oxides and causing air pollution. At the same time, the process flow is long and the operation is cumbersome. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for separating and recovering silver, copper and iron from silver-copper-iron composite waste. The method for separating and recovering silver, copper and iron from silver-copper-iron composite waste provided by the present invention can realize the separation and recovery of iron, silver and copper, and the method has a short process flow, is simple to operate, does not require the use of concentrated acid, and is green and environmentally friendly.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for separating and recovering silver, copper and iron from silver-copper-iron composite waste, comprising the following steps:

[0007] The silver-copper-iron composite waste is mixed with a sulfuric acid solution and subjected to a replacement reaction to obtain the silver-copper composite waste and a ferrous sulfate solution; the mass concentration of the sulfuric acid solution is 5-10%;

[0008] The silver-copper composite waste is subjected to vacuum volatilization to obtain silver vapor and copper respectively; the vacuum volatilization temperature is 1100-1400° C.;

[0009] The ferrous sulfate solution is crystallized to obtain ferrous sulfate.

[0010] Preferably, the volume ratio of the mass of the silver-copper-iron composite waste to the sulfuric acid solution is 1 kg: (4-6) L.

[0011] Preferably, the temperature of the replacement reaction is 40-60° C., and the time of the replacement reaction is 20-40 minutes.

[0012] Preferably, the temperature of the vacuum volatilization is 1100-1300° C., and the time of the vacuum volatilization is 1-3 hours.

[0013] Preferably, the temperature of the vacuum volatilization is 1250° C., and the time of the vacuum volatilization is 2 hours.

[0014] Preferably, the pressure of the vacuum volatilization is 0.01-10 Pa.

[0015] Preferably, the ferrous ion content in the ferrous sulfate solution is 80-110 g / L.

[0016] Preferably, the crystallization method is cooling crystallization.

[0017] Preferably, the silver vapor is condensed to obtain solid silver.

[0018] Preferably, the silver-copper-iron composite scrap comprises the following components by mass percentage: 35-40% Ag, 45-50% Cu and 10-15% Fe.

[0019] The present invention provides a method for separating and recovering silver, copper, and iron from silver-copper-iron composite waste, comprising: mixing the silver-copper-iron composite waste with a sulfuric acid solution, then subjecting the mixture to a replacement reaction to obtain silver-copper composite waste and a ferrous sulfate solution; the mass concentration of the sulfuric acid solution being 5-10%; subjecting the silver-copper composite waste to vacuum volatilization to obtain silver vapor and copper, respectively; the temperature of the vacuum volatilization being 1100-1400°C; and crystallizing the ferrous sulfate solution to obtain ferrous sulfate. The present invention separates iron from the silver-copper composite waste by mixing the silver-copper-iron composite waste with a sulfuric acid solution of a certain concentration, then subjecting the mixture to a replacement reaction, and subsequently crystallizing the ferrous sulfate solution to obtain ferrous sulfate, thereby recovering the iron; subjecting the silver-copper composite waste to vacuum volatilization, and by controlling the vacuum volatilization temperature, volatilizing the silver in the silver-copper composite waste to obtain silver vapor and remaining copper, thereby achieving the separation and recovery of silver and copper. The separation and recovery method provided by the present invention has a short process flow, is simple to operate, does not require the use of concentrated acid, and is environmentally friendly. The results of the examples show that the separation and recovery method provided by the present invention can obtain a silver yield of 98.85%, a copper yield of 99.11%, and ferrous sulfate with a purity of 99.61%. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a flow chart of a method for separating and recovering silver, copper and iron from silver-copper-iron composite waste in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The present invention provides a method for separating and recovering silver, copper and iron from silver-copper-iron composite waste, comprising:

[0022] The silver-copper-iron composite waste is mixed with a sulfuric acid solution and subjected to a replacement reaction to obtain the silver-copper composite waste and a ferrous sulfate solution;

[0023] volatilizing the silver-copper composite waste in a vacuum to obtain silver vapor and copper;

[0024] The ferrous sulfate solution is crystallized to obtain ferrous sulfate.

[0025] The separation and recovery method provided by the present invention is applicable to silver-copper-iron composite waste of various sources and compositions. In the present invention, the silver-copper-iron composite waste preferably includes silver-copper-iron composite strip waste.

[0026] In the present invention, the silver-copper-iron composite scrap preferably comprises the following components by mass percentage: 35-40% Ag, 45-50% Cu and 10-15% Fe, preferably 37% Ag, 47% Cu and 13% Fe.

[0027] The invention mixes silver-copper-iron composite waste with sulfuric acid solution and then performs replacement reaction to obtain the silver-copper composite waste and ferrous sulfate solution.

[0028] In the present invention, the silver-copper-iron composite scrap is preferably cut before use. The present invention has no particular limitation on the cutting method, and any cutting method known in the art can be used.

[0029] In the present invention, the length of the silver-copper-iron composite scrap after cutting is preferably 5 to 15 cm. In a specific embodiment of the present invention, the length of the silver-copper-iron composite scrap after cutting can be specifically 5 cm, 10 cm, or 15 cm. By limiting the length of the silver-copper-iron composite scrap, the present invention allows for more complete mixing with the sulfuric acid solution to undergo the replacement reaction.

[0030] In the present invention, the mass concentration of the sulfuric acid solution is preferably 5-10%. In specific embodiments of the present invention, the mass concentration of the sulfuric acid solution can be specifically 5%, 7%, 8%, 9%, or 10%. By limiting the mass concentration of the sulfuric acid solution, the present invention ensures that the iron in the silver-copper-iron composite waste more fully undergoes a replacement reaction with the sulfuric acid solution, while the silver-copper waste does not react, thereby more fully achieving the separation of iron from the silver-copper waste.

[0031] In the present invention, the mass ratio of the silver-copper-iron composite waste to the volume ratio of the sulfuric acid solution is preferably 1 kg: (4-6) L. In specific embodiments of the present invention, the volume ratio of the silver-copper-iron composite waste to the sulfuric acid solution can be specifically 1 kg: 4 L, 1 kg: 5 L, or 1 kg: 6 L. By limiting the volume ratio of the silver-copper-iron composite waste to the sulfuric acid solution, the present invention further ensures that the iron in the silver-copper-iron composite waste reacts more fully with the sulfuric acid solution, thereby more fully achieving the separation of iron from the silver-copper waste.

[0032] In the present invention, the mixing of the silver-copper-iron composite waste and the sulfuric acid solution is preferably carried out under stirring. In the present invention, the stirring rate is preferably 1 to 10 rpm. In a specific embodiment of the present invention, the stirring rate can be specifically 1 rpm, 5 rpm, or 10 rpm.

[0033] In the present invention, in the replacement reaction, sulfuric acid reacts with the iron in the silver-copper-iron composite waste to generate a ferrous sulfate solution, and the silver-copper waste does not react, thereby achieving the separation of iron from the silver-copper waste. In the present invention, the temperature of the replacement reaction is preferably 40 to 60°C. In a specific embodiment of the present invention, the temperature of the replacement reaction may be specifically 40°C, 50°C or 60°C. In the present invention, the time of the replacement reaction is preferably 20 to 40 minutes. In a specific embodiment of the present invention, the time of the replacement reaction may be specifically 20 minutes, 30 minutes or 40 minutes. The present invention further ensures that sulfuric acid reacts with the iron in the silver-copper-iron composite waste to generate a ferrous sulfate solution by limiting the temperature and time of the replacement reaction, thereby more fully achieving the separation of iron from the silver-copper waste.

[0034] After the replacement reaction is completed, the present invention preferably performs solid-liquid separation on the replaced product to obtain a ferrous sulfate solution and silver-copper composite waste.

[0035] After obtaining the silver-copper composite waste, the present invention performs vacuum volatilization on the silver-copper composite waste to obtain silver vapor and copper.

[0036] In the present invention, the temperature of the vacuum volatilization is preferably 1100-1400°C. In embodiments of the present invention, the temperature of the vacuum volatilization may specifically be 1100°C, 1200°C, 1250°C, 1300°C, or 1400°C. By limiting the temperature of the vacuum volatilization, the present invention ensures that silver is more fully volatilized into silver vapor while copper does not volatilize. In the present invention, the time of the vacuum volatilization is preferably 1-3 hours. In embodiments of the present invention, the time of the vacuum volatilization may specifically be 1 hour, 2 hours, or 3 hours. In the present invention, the heating rate of the vacuum volatilization is preferably 5-10°C / min. In embodiments of the present invention, the heating rate of the vacuum volatilization may specifically be 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, or 10°C / min. In the present invention, the pressure of the vacuum volatilization is preferably 0.01-10 Pa. In embodiments of the present invention, the pressure of the vacuum volatilization may specifically be 0.01 Pa, 1 Pa, 5 Pa, or 10 Pa. The present invention limits the parameters of vacuum volatilization to ensure that the silver in the silver-copper waste is more fully volatilized into silver vapor.

[0037] In the present invention, the silver vapor is preferably condensed to obtain solid silver. The present invention has no particular limitation on the condensation method of the silver vapor, and the silver vapor can be cooled to obtain solid silver using a cooling method well known in the art.

[0038] After obtaining the ferrous sulfate solution, the present invention crystallizes the ferrous sulfate solution to obtain ferrous sulfate.

[0039] In the present invention, the ferrous ion content in the ferrous sulfate solution is preferably 80 to 110 g / L. In the present invention, the ferrous ion content in the ferrous sulfate solution is preferably measured by a potentiometric titrator. In an embodiment of the present invention, the ferrous ion content in the ferrous sulfate solution may specifically be 80 g / L, 95 g / L, or 110 g / L. The present invention limits the ferrous ion content in the ferrous sulfate solution to ensure a more complete separation of the iron in the silver-copper-iron composite waste from the silver-copper waste, to more fully improve the utilization rate of the sulfuric acid solution, and to be more conducive to taking into account the purity of ferrous sulfate, crystal quality, and crystallization efficiency.

[0040] As an embodiment of the present invention, when the ferrous ion content in the ferrous sulfate solution is less than 100 g / L, the ferrous sulfate solution can continue to be mixed with new silver-copper-iron composite waste to carry out a replacement reaction.

[0041] In the present invention, the crystallization method is preferably cooling crystallization. In the present invention, the cooling crystallization time is preferably 3 to 5 hours. In an embodiment of the present invention, the cooling crystallization time can specifically be 3 hours, 4 hours or 5 hours.

[0042] In an embodiment of the present invention, a flow chart of a method for separating and recovering silver, copper and iron from silver-copper-iron composite waste is shown in FIG. Figure 1 As shown, the silver-copper-iron composite strip waste is mechanically cut to obtain cut silver-copper-iron composite strip waste, and then a certain concentration of sulfuric acid solution is added to obtain ferrous sulfate solution and silver-copper composite strip waste respectively. Thereafter, the obtained ferrous sulfate solution is continued to react with the cut silver-copper-iron composite strip waste. When the ferrous ions in the ferrous sulfate solution reach a certain concentration, it is cooled and crystallized to obtain ferrous sulfate; and the obtained silver-copper composite strip waste is vacuum volatilized to obtain silver and copper respectively.

[0043] The present invention separates iron from the silver-copper composite waste by mixing the silver-copper composite waste with a sulfuric acid solution and then performing a replacement reaction. Subsequently, the ferrous sulfate solution is crystallized to obtain ferrous sulfate, thereby realizing iron recovery. The silver-copper composite waste is subjected to vacuum volatilization. During the vacuum volatilization process, silver volatilizes to obtain silver vapor and remaining copper, thereby realizing the separation and recovery of silver and copper. The separation and recovery method provided by the present invention has a short process flow, is simple to operate, does not require the use of concentrated acid, and is environmentally friendly.

[0044] In order to further illustrate the present invention, the present invention is described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0045] Example 1

[0046] A method for separating and recovering silver, copper and iron from silver-copper-iron composite waste:

[0047] 10 kg of silver-copper-iron composite strip waste containing 39.52% Ag, 48.85% Cu, and 11.63% Fe by mass was mechanically crushed into pieces 5 cm in length and placed in a reactor. The pieces were then mixed with 40 L of a 5% sulfuric acid solution at 1 rpm and reacted at 70° C. for 3 hours. The mixture was then filtered to obtain the silver-copper composite strip waste and a ferrous sulfate solution, respectively. The ferrous sulfate solution was further reacted with new silver-copper-iron composite strip waste. The volume ratio of the silver-copper-iron composite strip waste to the sulfuric acid solution was 1 kg:4 L.

[0048] The silver-copper composite strip waste is placed in a crucible, a condenser plate is placed on the crucible, and the crucible is placed in a vacuum furnace for vacuum volatilization at 1100° C. for 1 hour to obtain silver solid and copper; the vacuum volatilization temperature is increased at a rate of 5° C. / min; and the vacuum volatilization pressure is 0.01 Pa;

[0049] The ferrous sulfate solution was measured by a potentiometric titrator to determine if the ferrous ion content reached 80 g / L, and then cooled and crystallized for 3 hours to obtain ferrous sulfate.

[0050] In this embodiment, the silver yield reaches 98.13%, the copper yield reaches 99.05%, and the purity of ferrous sulfate reaches 97.95%.

[0051] Example 2

[0052] A method for separating and recovering silver, copper and iron from silver-copper-iron composite waste comprises the following steps:

[0053] 10 kg of silver-copper-iron composite strip waste containing 37.8% Ag, 48.83% Cu, and 13.37% Fe by mass was mechanically crushed into 10 cm long pieces and placed in a reactor. The mixture was then mixed with 50 L of 8% sulfuric acid solution at 5 rpm and reacted at 70° C. for 2.5 hours. The mixture was then filtered to obtain the silver-copper composite strip waste and a ferrous sulfate solution, respectively. The ferrous sulfate solution was further reacted with new silver-copper-iron composite strip waste. The mass ratio of the silver-copper-iron composite strip waste to the sulfuric acid solution was 1 kg:5 L.

[0054] The silver-copper composite strip scrap is placed in a crucible, a condenser plate is placed on the crucible, and the crucible is placed in a vacuum furnace for vacuum volatilization at 1250° C. for 2 hours to obtain silver solid and copper; the vacuum volatilization temperature is increased at a rate of 7° C. / min; and the vacuum volatilization pressure is 1 Pa;

[0055] The ferrous sulfate solution was measured by a potentiometric titrator to determine if the ferrous ion content reached 95 g / L, and then cooled and crystallized for 4 hours to obtain ferrous sulfate.

[0056] In this embodiment, the silver yield reaches 98.95%, the copper yield reaches 99.11%, and the purity of ferrous sulfate reaches 99.58%.

[0057] Example 3

[0058] A method for separating and recovering silver, copper and iron from silver-copper-iron composite waste comprises the following steps:

[0059] 10 kg of silver-copper-iron composite strip waste containing 35.58% Ag, 49.70% Cu, and 14.72% Fe by mass was mechanically crushed into 15 cm in length and placed in a reactor. The waste was then mixed with 60 L of a 10% sulfuric acid solution at 10 rpm and reacted at 80° C. for 2 h. The mixture was then filtered to obtain the silver-copper composite strip waste and a ferrous sulfate solution, respectively. The ferrous sulfate solution was further reacted with new silver-copper-iron composite strip waste. The volume ratio of the silver-copper-iron composite strip waste to the sulfuric acid solution was 1 kg:6 L.

[0060] The silver-copper composite strip scrap is placed in a crucible, a condenser plate is placed on the crucible, and the crucible is placed in a vacuum furnace for vacuum volatilization at 1400° C. for 3 hours to obtain silver solid and copper; the vacuum volatilization temperature is increased at a rate of 10° C. / min; and the vacuum volatilization pressure is 10 Pa;

[0061] The ferrous sulfate solution was measured by a potentiometric titrator to determine if the ferrous ion content reached 110 g / L, and then cooled and crystallized for 5 hours to obtain ferrous sulfate.

[0062] In this embodiment, the silver yield reaches 98.31%, the copper yield reaches 98.73%, and the purity of ferrous sulfate reaches 99.61%.

[0063] In summary, the method for separating and recovering silver, copper and iron from silver-copper-iron composite waste provided by the present invention can realize the separation and recovery of iron, silver and copper, and the method has a short process flow, is easy to operate, does not require the use of concentrated acid, and is green and environmentally friendly.

[0064] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for separating and recovering silver, copper and iron from silver-copper-iron composite waste, comprising: The silver-copper-iron composite waste is mixed with a sulfuric acid solution and subjected to a replacement reaction to obtain the silver-copper composite waste and a ferrous sulfate solution; The mass concentration of the sulfuric acid solution is 5-10%; The silver-copper composite waste is subjected to vacuum volatilization to obtain silver vapor and copper; the vacuum volatilization temperature is 1100-1400° C.; The ferrous sulfate solution is crystallized to obtain ferrous sulfate.

2. The separation and recovery method according to claim 1, wherein The volume ratio of the mass of the silver-copper-iron composite waste to the sulfuric acid solution is 1 kg: (4-6) L.

3. The separation and recovery method according to claim 1 or 2, characterized in that: The temperature of the replacement reaction is 40 to 60° C., and the time of the replacement reaction is 20 to 40 minutes.

4. The separation and recovery method according to claim 1, wherein: The temperature of the vacuum volatilization is 1100-1300° C., and the time of the vacuum volatilization is 1-3 hours.

5. The separation and recovery method according to claim 4, characterized in that: The temperature of the vacuum volatilization is 1250° C., and the time of the vacuum volatilization is 2 hours.

6. The separation and recovery method according to claim 1, 4 or 5, characterized in that: The pressure of the vacuum volatilization is 0.01-10 Pa.

7. The separation and recovery method according to claim 1, characterized in that: The ferrous ion content in the ferrous sulfate solution is 80-110 g / L.

8. The separation and recovery method according to claim 1, wherein: The crystallization method is cooling crystallization.

9. The separation and recovery method according to claim 1, characterized in that: The silver vapor is condensed to obtain solid silver.

10. The separation and recovery method according to claim 1, characterized in that: Calculated by mass percentage, the silver-copper-iron composite scrap includes the following components: 35-40% Ag, 45-50% Cu and 10-15% Fe.

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