KR20200111982A - Recovery method of silver from leaching solution of waste solar wafer - Google Patents

Abstract

The present invention relates to a method for collecting silver from the leachate of a waste solar cell. In particular, according to one embodiment of the present invention, the method for collecting silver from the leachate of a waste solar cell comprises: a step of allowing a waste solar cell to come in contact with an acid solution to prepare a leachate containing silver (Ag) and aluminum (Al); a step of preparing a mixture containing the leachate and an extraction agent; a step of separating an organic phase containing silver and an aqueous phase containing aluminum from the mixture; and a step of allowing the organic phase to come in contact with a first stripping agent to obtain a first processing solution containing silver and a filtrate. Here, the extraction agent contains trioctylphosphine oxide. Therefore, silver can be selectively collected from a waste solar cell.

Description

Silver recovery method from waste solar cell leachate {RECOVERY METHOD OF SILVER FROM LEACHING SOLUTION OF WASTE SOLAR WAFER}

The present invention relates to a method for recovering silver from leachate from waste solar cells.

In the manufacture of solar cell modules, silver (Ag) is used to metallize the entire surface of silicon solar cells by screen printing. As the production and installation of photovoltaic systems increases, the number of waste photovoltaic modules is steadily increasing, and the recycling of such devices is very important in terms of resource recycling and environment. The recovery of silicon (Si), which is a major component of a solar cell module, has been widely performed, but silver (Ag) has been generally removed or ignored. Due to the recent increase in silver demand and strict environmental policies, it is very important to recover silver from consumed silicon solar cells.

Conventionally, silver (Ag) is recovered and removed from a silicon solar cell by wet smelting treatment through etching in nitric acid solution, or is recovered by precipitation method after dissolving silver (Ag) with hydrochloric acid, but there is a problem that solid-liquid separation is difficult. In addition, the solvent extracting agent cyanex 301, which is well known as a solvent extraction method, has been discontinued, and extracting agents such as LIX 63, which are currently widely used, have a problem of high cost, and the extractants have a problem of low stability against acid, making it difficult to commercialize them. There was this.

As a background technology related to the present invention, there is Japanese Patent Publication No. 5002615 (Announcement on August 15, 2012, title of the invention: Method of recycling valuable metals).

One object of the present invention is to provide a method for recovering silver from waste solar cell leachate, which can selectively recover silver from waste solar cells.

Another object of the present invention is to provide a method for recovering silver from waste solar cell leachate, which has excellent silver recovery and can recover aluminum.

Another object of the present invention is to provide a method for recovering silver from waste solar cell leachate, which is capable of regenerating an extractant and has excellent economic efficiency.

One aspect of the present invention relates to a method for recovering silver from waste solar cell leachate. In one embodiment, the method for recovering silver from the waste solar cell leachate comprises: preparing a leachate containing silver (Ag) and aluminum (Al) by contacting the waste solar cell with an acid solution; Preparing a mixture comprising the leachate and an extractant; Separating an organic phase and an aqueous phase containing silver from the mixture; And contacting the organic phase with the first stripping agent to obtain a first treatment solution and a filtrate containing silver, wherein the extracting agent includes trioctyl phosphine oxide.

In one embodiment, the concentration of the acid solution may be 0.5M or less.

In one embodiment, the extractant may include trioctylphosphine oxide mixed in a hydrocarbon-based solvent at a concentration of 0.05 to 1M.

In one embodiment, the hydrocarbon-based solvent may include one or more of kerosene, toluene, xylene, benzene, and cyclohexane.

In one embodiment, the leachate and extractant may be included in a volume ratio of 1:0.2 to 1:5.

In one embodiment, the organic phase and the aqueous phase may be included in a volume ratio of 1:0.2 to 1:5.

In one embodiment, the first stripping agent includes thiourea, and the concentration of the first stripping agent may be 0.05M or more.

In one embodiment, the organic phase and the first stripping agent may be contacted in a volume ratio of 1:0.2 to 1:5.

In one embodiment, contacting the filtrate with a second stripper to remove aluminum contained in the filtrate, and regenerating the extractant; may further include.

In one embodiment, the concentration of the second stripping agent may be 3M or more.

In one embodiment, the filtrate and the second stripper may be contacted in a volume ratio of 1:0.2 to 1:5.

When applying the silver recovery method from the waste solar cell leachate according to the present invention, silver can be selectively recovered, the silver recovery rate is high, aluminum can be recovered, the extractant can be regenerated, and the economy can be excellent. .

1 shows a method of recovering silver from leachate from a waste solar cell according to an embodiment of the present invention.
2 is a graph showing a change in recovery rate of silver and aluminum in an aqueous phase according to a change in acid concentration when extracting silver and aluminum using the extractant of the present invention.
3 is a graph showing the change in the recovery rate of silver and aluminum in the aqueous phase according to the change of trioctylphosphine oxide in the extractant of the present invention.
4 shows a McCabe-Seal diagram for determining the process conditions for extracting the total amount of silver from the leachate of the present invention.
5 is a graph showing the silver and aluminum stripping rates in the organic phase according to the concentration of the first stripping agent of the present invention.

In describing the present invention, if it is determined that a detailed description of a related known technology or configuration may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted.

In addition, terms to be described later are terms defined in consideration of functions in the present invention and may vary according to the intentions or customs of users and operators, and thus their definitions should be made based on the contents throughout the present specification describing the present invention.

Silver recovery method from waste solar cell leachate

One aspect of the present invention relates to a method for recovering silver from waste solar cell leachate. 1 shows a method of recovering silver from leachate from a waste solar cell according to an embodiment of the present invention.

Referring to FIG. 1, the method of recovering silver from the waste solar cell leachate includes (S10) a leachate preparation step; (S20) a mixture preparation step; (S30) organic phase and aqueous phase separation step; (S40) silver ion stripping step; includes. More specifically, the present invention comprises the steps of (S10) contacting the waste solar cell with an acid solution to prepare a leachate containing silver (Ag) and aluminum (Al); (S20) preparing a mixture containing the leachate and an extractant; (S30) separating an organic phase containing silver and an aqueous phase containing aluminum from the mixture; And (S40) contacting the organic phase with the first stripping agent to obtain a first treatment liquid and a filtrate containing silver. The extracting agent includes trioctyl phosphine oxide.

Hereinafter, the aspect according to the present invention will be described in detail step by step a method of recovering silver from leachate from waste solar cells.

(S10) leachate manufacturing step

The step is a step of preparing a leachate containing silver (Ag) and aluminum (Al) by contacting the waste solar cell with an acid solution.

In one embodiment, the waste solar cell may include a waste solar cell module. In one embodiment, the solar cell module includes a tempered glass layer; At least one solar cell provided on a lower surface of the tempered glass layer; A back sheet layer formed on a lower surface of the solar cell; An adhesive layer formed between the tempered glass layer and the solar cell; And a frame formed along the outer circumferential surface of the tempered glass layer, the adhesive layer, and the back sheet layer. The solar cell serves to convert light energy into electrical energy, and two or more solar cell cells may be connected in series or in parallel through a conductive ribbon. The solar cell may include silver (Ag), silicon (Si), and aluminum (Al).

In one embodiment, after removing the tempered glass layer, the adhesive layer, and the frame of the waste solar cell module, it may be prepared by washing and pulverizing the solar cell.

In one embodiment, the acid solution may include nitric acid (HNO ₃ ). When the acid solution is applied, silver and aluminum contained in the waste solar cell can be easily dissolved to prepare a leachate. For example, the acid solution may include an aqueous nitric acid solution.

In one embodiment, the silver (Ag) may include a monovalent silver ion (Ag ⁺ ), and the aluminum may include a trivalent aluminum ion (Al ^{3 +} ).

In one embodiment, the concentration of the acid solution may be 0.5M (mol/L) or less. When included in the above concentration, silver and aluminum contained in the waste solar cell can be easily dissolved to prepare a leachate. When the concentration of the acid solution exceeds 0.5M, the silver extraction efficiency may rapidly decrease. For example, it may be 0.001 ~ 0.5M. For another example, it may be 0.001 to 0.01M.

(S20) Mixture preparation step

The step is a step of preparing a mixture containing the leachate and an extractant. The extracting agent includes trioctyl phosphine oxide. When the extracting agent is applied, the selectivity to silver is excellent, so that the silver contained in the leachate can be selectively extracted.

In one embodiment, the extractant may include trioctylphosphine oxide mixed in a hydrocarbon-based solvent at a concentration of 0.05 to 1M. When the above concentration of trioctylphosphine oxide is applied, silver contained in the leachate may be selectively extracted. For example, it may be included in a concentration of 0.5 to 1M.

In one embodiment, the hydrocarbon-based solvent may include one or more of kerosene, toluene, xylene, benzene, and cyclohexane. When the hydrocarbon-based solvent is included, silver may be selectively extracted from the organic phase to be described later. For example, it may contain kerosene.

In one embodiment, the leachate and extractant may be included in a volume ratio of 1:0.2 to 1:5. Under the above conditions, the extraction efficiency of silver contained in the leachate may be excellent. For example, the leachate and extractant may be included in a volume ratio of 1:0.8 to 1:1.5.

(S30) Organic phase and aqueous phase separation step

The step is a step of separating an organic phase and an aqueous phase containing silver from the mixture. In one embodiment, when the mixture is allowed to stand and the organic phase and the aqueous phase are separated, the organic phase and the aqueous phase may be separated using a separation funnel or the like.

In one embodiment, the organic phase may include the silver, aluminum and an extracting agent. The aqueous phase may contain the above-described aluminum and acid solution.

The organic phase and the aqueous phase may be included in a volume ratio of 1:0.2 to 1:5. In the above range, the extraction efficiency of silver may be excellent. For example, it may be included in a volume ratio of 1:0.8-1:1.5.

(S40) Silver ion Removal step

The step is a step of removing silver by contacting the separated organic phase with a first stripping agent to obtain a first treatment liquid and a filtrate containing silver.

For example, the first treatment liquid may be an aqueous phase, and the filtrate may be an organic phase.

In one embodiment, the filtrate may contain aluminum and the extractant component.

In one embodiment, the concentration of the first stripping agent may be 0.05M or more. When the concentration of the first stripping agent is less than 0.05M, the stripping efficiency of silver may be significantly reduced. In addition, when the concentration of the first stripping agent is 0.1M or more, the entire amount of silver in the organic phase may be stripped. For example, the concentration of the first stripping agent may be 0.1 ~ 5M.

In one embodiment, the organic phase and the first stripping agent may be contacted in a volume ratio of 1:0.2 to 1:5. When contacting with the volume ratio, the removal efficiency of silver may be excellent. For example, the organic phase and the first stripping agent may be contacted in a 1:1 volume ratio.

(S50) Extractant regeneration step

Referring to FIG. 1, the step of contacting the filtrate with a second stripper to remove aluminum contained in the filtrate to regenerate the extractant; may further include.

In one embodiment, when the filtrate and the second stripping agent are brought into contact with each other and then left to stand, aluminum ions contained in the filtrate containing the extracting agent may be stripped and separated into a second treatment liquid layer and a regenerated extracting agent layer. By separating this using a separating funnel layer, the extractant component can be recycled.

In one embodiment, when an aqueous nitric acid solution is used as the second stripping agent, the second treatment liquid may include aluminum nitrate.

In one embodiment, the second stripping agent may include nitric acid. When the second stripping agent is applied, aluminum stripping efficiency may be excellent. For example, it may contain an aqueous nitric acid solution. In one embodiment, the concentration of the second stripping agent may be 3M or more. When applied under the above concentration conditions, the removal efficiency of aluminum contained in the filtrate may be excellent. For example, it may be 3 to 8M.

In one embodiment, the filtrate and the second stripper may be contacted in a volume ratio of 1:0.2 to 1:5. When contacting at the volume ratio, the aluminum stripping efficiency may be excellent. For example, the filtrate and the second stripping agent may be contacted in a 1:1 volume ratio.

When applying the silver recovery method from the waste solar cell leachate according to the present invention, silver can be selectively recovered, the silver recovery rate is high, aluminum can be recovered, the extractant can be regenerated, and the economy can be excellent. .

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, this is presented as a preferred example of the present invention and cannot be construed as limiting the present invention in any sense. Contents not described herein can be sufficiently technically inferred by those skilled in the art, and thus description thereof will be omitted.

Example

After removing the tempered glass layer, the adhesive layer, and the frame of the waste solar cell module, the solar cell including silicon, aluminum, and silver was washed and pulverized to prepare a waste solar cell in the form of a pulverized product.

A leachate was prepared by contacting the waste solar cell with 1 M of nitric acid (HNO ₃ ) aqueous solution. A leachate containing 0.001 M silver (Ag), 0.0195 M aluminum (Al), and 0.01 M nitric acid (HNO ₃ ) was prepared by the distillation method.

Trioctyl phosphine oxide was prepared by mixing trioctyl phosphine oxide as an extract at a concentration of 0.5 M in kerosene, and then the leachate and an extractant were mixed to prepare a mixture. The mixture was allowed to stand, and the layers were separated into an organic phase containing silver ions (Ag ⁺ ) and an aqueous phase containing aluminum ions (Al ^{3 +} ), and then separated using a separatory funnel.

The separated organic phase and the first stripping agent (aqueous solution of thiourea having a concentration of 0.1M) were brought into contact and mixed, and then allowed to stand, and separated into a first treatment liquid layer and a filtrate layer of an aqueous phase. Then, separation was performed using a separating funnel to obtain a first treatment liquid containing silver ions and a filtrate containing a trace amount of aluminum ions.

Then, the filtrate and the second stripper (5M aqueous nitric acid solution) were brought into contact and mixed, and then allowed to stand to separate into a second treatment liquid layer and a regenerated extractant layer. Then, separation was performed using a separating funnel to obtain a second treatment liquid containing aluminum (aluminum nitrate) and a regenerated extractant.

Then, the first treatment liquid and the second stripper (5M aqueous nitric acid solution) were brought into contact and mixed, and then left to stand to separate the second treatment liquid layer and the regenerated extractant layer. Then, separation was performed using a separating funnel to obtain a second treatment liquid containing aluminum (aluminum nitrate) and a regenerated extractant.

As a result of comparing the content of silver contained in the waste solar cell with the content of silver ions contained in the second treatment liquid, a silver recovery rate of 99.9% or more was obtained when the recovery method of the present invention was applied.

Experimental example

(1) Evaluation of the effect of acid concentration in leachate on silver and aluminum extraction

The following test was performed to evaluate the effect of the concentration of acid (nitric acid (HNO ₃ )) in the leachate on silver and aluminum extraction.

The organic phase and the aqueous phase obtained through the above examples were each added to a disposable photosphere bottle (100ml) by 20ml (organic phase:aqueous phase = 1:1 volume ratio). At this time, the concentration of nitric acid (HNO ₃ ) contained in the aqueous phase was changed to 0.001 to 1.5M, and the concentration of trioctylphosphine oxide contained in the organic phase was fixed to 0.5M. The aqueous phase and the organic phase were mixed for each concentration, stirred for 30 minutes, allowed to stand, and the aqueous phase and the organic phase were separated, and the aqueous phase and the organic phase were separated with a separation funnel.

The organic phase, the aqueous phase before the reaction, and the aqueous phase after the reaction were analyzed with an Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES, PerkinElmer Optima 8300), respectively, and the metal concentration in the organic phase was determined by mass balance. It was measured through and the results are shown in FIG. 2 below.

2 is a graph showing a change in recovery rate of silver and aluminum in an aqueous phase according to a change in acid concentration when extracting silver and aluminum using the extractant of the present invention. Referring to the result of FIG. 2, the extraction of silver by the extractant of the present invention rapidly decreased as the nitric acid concentration increased from 0.001M to 1.5M. When the nitric acid concentration of the aqueous phase was 0.01M, the extraction rate of silver was 80%. On the other hand, aluminum was less than 10% extraction rate in the range of 0.001 to 1.5M nitric acid. Through this, it was found that the extractant of the present invention has superior selectivity to silver than aluminum at an acid (nitric acid) concentration of 0.5 mol/L or less.

(2) Evaluation of the effect of extractant concentration on silver and aluminum extraction

The following test was performed to evaluate the effect of the concentration of trioctyl phosphine oxide (TOPO) contained in the extractant on silver and aluminum extraction.

20 ml of the organic phase and the aqueous phase obtained through the above examples were each added to a disposable photo-mouth bottle (100 ml) (organic phase: aqueous phase = 1:1 volume ratio). At this time, the concentration of nitric acid (HNO ₃ ) contained in the aqueous phase was fixed to 0.01M, and the concentration of trioctylphosphine oxide in the extractant contained in the organic phase was changed to 0.001 to 0.5M. The organic phase and the aqueous phase were mixed for each concentration, stirred for 30 minutes, and allowed to stand. After the aqueous phase and the organic phase were separated, the aqueous phase and the organic phase were separated by a separation funnel.

The organic phase, the aqueous phase before the reaction, and the aqueous phase after the reaction were analyzed with an Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES, PerkinElmer Optima 8300), respectively, and the metal concentration in the organic phase was determined by mass balance. It was measured through and the results are shown in FIG. 3 below.

3 is a graph showing the change in the recovery rate of silver and aluminum in the aqueous phase according to the change of trioctylphosphine oxide (TOPO) in the extractant of the present invention. Referring to the results of FIG. 3, when the concentration of trioctylphosphine oxide in the extractant was 0.2 M or more, the silver extraction rate was 60% or more. The aluminum extraction rate slightly increased as the trioctylphosphine oxide concentration increased, but was less than 5%. Through this, it was found that the silver and aluminum can be completely separated by extraction through trioctylphosphine oxide.

(3) Determination of the theoretical number of stages necessary for complete extraction of silver in the leachate

In order to extract the entire amount of silver in the leachate, a McCabe-Thiele diagram was constructed as follows, and the results are shown in FIG. 4. 4 shows a McCabe-Seal diagram for determining the optimal process conditions for extracting the total amount of silver from the leachate of the present invention.

Referring to FIG. 4, when applying nitric acid of 0.01M concentration contained in the aqueous phase, the volume ratio (O:A) of the organic phase and the aqueous phase was changed from 1:0.2 to 1:5, and the aqueous phase was composed of 0.5 M. This is the result of contact with the extractant. At this time, as the volume ratio (O:A) of the organic phase and the aqueous phase changes from 1:0.2 to 1:5, the extraction ratio of silver increased from 52% to 98% at the fixed acid concentration, whereas aluminum (III) was from 0 Increased to 28%.

On the other hand, when the volume ratio of the organic phase and the aqueous phase was 1:1, 2.7% of Al (III) was extracted by the extracting agent together with Ag (I). In addition, referring to FIG. 4, it indicates that the quantitative extraction of Ag using the extracting agent proceeds in three steps in (organic phase: aqueous phase = 1:1). In order to confirm the estimated number of stages in the McCabe-Seal diagram, a simulation experiment was performed with a 3-step reverse extraction at an A:O volume ratio of 1:1. As a result of the simulation experiment, it was found that silver was completely extracted after three-step extraction, and 2.9% of aluminum was simultaneously extracted from the added extractant.

(4) using the first stripper Stripping process Condition decision

In the organic phase containing silver and aluminum, the following experiment was performed to determine the conditions of the stripping process for stripping the silver.

An organic phase containing an extractant including silver ions and aluminum ions obtained in the above example was prepared. A first stripping agent (thiourea) was prepared at a concentration of 0.01 to 1 M, and the results of stripping by contacting each of the organic phases are shown in FIG. 5 below.

5 is a graph showing the silver and aluminum stripping rates in the organic phase according to the concentration of the first stripping agent of the present invention. As shown in FIG. 5, as the concentration of thiourea increased, the removal rate of silver increased. When the concentration of thiourea increases by 0.1 M or more, complete removal of silver is performed, and when the concentration of thiourea is 0.05-1 M, removal of aluminum contained in the organic phase hardly occurs.

(5) Determination of process conditions for regeneration of extractant

An organic phase was prepared in the same manner as in Experimental Example 4. Then, 0.1 M of thiourea was used to contact the organic phase to remove the silver, and the first treatment liquid (aqueous phase) containing silver and the filtrate were separated.

In order to efficiently remove the aluminum from the aluminum-containing filtrate, nitric acid was used as a second stripping agent. The filtrate containing aluminum and an aqueous solution of 2M, 3M and 5M nitric acid were contacted in a 1:1 volume ratio. As a result, it was found that the aluminum removal rate increased from 98% to 99.999% as the concentration of the second stripping agent increased from 2M to 5M. From these results, it was found that a nitric acid (HNO ₃ ) aqueous solution was suitable as the second stripping agent, and when the second stripping agent was added in an amount of 3M or more, aluminum could be quantitatively stripped.

Simple modifications or changes of the present invention can be easily implemented by those of ordinary skill in the art, and all such modifications or changes can be considered to be included in the scope of the present invention.

Claims (11)

Preparing a leachate containing silver (Ag) and aluminum (Al) by contacting the waste solar cell with an acid solution;
Preparing a mixture comprising the leachate and an extractant;
Separating an organic phase containing silver and an aqueous phase containing aluminum from the mixture; And
Including; by contacting the organic phase and the first stripping agent to obtain a first treatment liquid and a filtrate containing silver; and
The method of recovering silver from waste solar cell leachate, characterized in that the extractant contains trioctyl phosphine oxide.
The method of claim 1, wherein the concentration of the acid solution is 0.5M or less.
The method of claim 1, wherein the extractant comprises trioctylphosphine oxide mixed with a hydrocarbon-based solvent at a concentration of 0.05 to 1M.
The waste solar cell of claim 3, wherein the hydrocarbon-based solvent comprises at least one of kerosene, toluene, xylene, benzene, and cyclohexane. How to recover silver from leachate.
The method of claim 1, wherein the leachate and extractant are contained in a volume ratio of 1:0.2 to 1:5.
The method of claim 1, wherein the organic phase and the aqueous phase are contained in a volume ratio of 1:0.2 to 1:5.
The method of claim 1, wherein the first stripping agent comprises thiourea,
Silver recovery method from waste solar cell leachate, characterized in that the concentration of the first stripping agent is 0.05M or more.
The method of claim 1, wherein the organic phase and the first stripping agent are in contact with each other in a volume ratio of 1:0.2 to 1:5.
The method of claim 1, further comprising: contacting the filtrate with a second stripper to remove aluminum contained in the filtrate and regenerating an extractant; .
9. The method of claim 8, wherein the concentration of the second stripping agent is 3M or more.
The method of claim 8, wherein the filtrate and the second stripping agent are in contact with each other in a volume ratio of 1:0.2 to 1:5.

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