CN103866129B - A kind of recovery method of CdTe solar module - Google Patents

Abstract

A method for recovering CdTe solar cell components, characterized in that: after the CdTe solar cell glass components from which the EVA encapsulation glue has been removed are fully etched in sulfuric acid/hydrogen peroxide solution, magnetic polymer microspheres are used to directly and rapidly remove the CdTe solar cell components Cd and Te elements are enriched in the acid etching solution, and the obtained high concentration Cd and Te etching solution can be further used in the electrolysis process. This recovery process has the characteristics of high enrichment and separation efficiency, simple process and easy realization of scale-up, and the magnetic polymer microspheres can be recycled.

Description

A kind of recovery method of CdTe solar cell module

technical field

The invention relates to the recycling technology of photovoltaic modules, in particular to a method for recycling and processing cadmium telluride thin-film solar cells.

Background technique

Cadmium telluride (CdTe) is a commercially available semiconductor material for solar energy conversion, with excellent light-absorbing properties and excellent module performance at high temperatures. In recent years, with the continuous improvement of CdTe battery technology, the conversion efficiency of its components has increased to 16.1% (0.72m ² components), occupying the second largest market share of solar cells after crystalline silicon cells, and its component production capacity in 2012 Has reached _1.8GWp . EPIA predicts that by 2020, the market share of CdTe solar cells will exceed 10%. However, the rapid growth of production capacity will inevitably lead to two major problems: first, the potential harm of the toxic Cd element to the environment; second, the insufficient supply of Te as a scarce element in the future. Therefore, it will be particularly important to develop a suitable recycling method for waste CdTe battery components.

A series of recycling techniques for CdTe solar cells have been reported and implemented. Among them, the combination of acid etching solution dissolution and hydrometallurgy technology is not only suitable for various types of waste CdTe solar cells, but also easy to realize commercial application in a short period of time. FirstSolar Company of the United States uses sulfuric acid/hydrogen peroxide system to acid-etch the CdTe layer in the module, and then adopts the method of sodium hydroxide step-by-step precipitation to enrich Cd and Te elements; since the compound type and solubility of Te element are greatly affected by the change of solution pH value, This results in an unavoidable large amount of Te element remaining in the solution, and it is difficult to control the pH value of the solution. World Patent No.WO2006/130715A2 describes the separation and recovery of Cd and Te elements in the CdTe etching solution by means of ion exchange column separation, but the column pressure will limit the treatment capacity of the acid etching solution; and the resin pollution caused by the ion exchange process and A clogged exchange column makes the exchange column renewal process cumbersome. US Patent No. US005997718A describes the separation of Te elements from CdTe etching solution by electrolysis, but the electrolysis efficiency is low and the economy is poor for low concentration etching solution. Therefore, it is urgent to develop an efficient and large-capacity enrichment and separation method that can directly enrich Cd and Te ions from the CdTe etching solution.

Contents of the invention

The purpose of the present invention is to overcome the disadvantages of using a large amount of chemical precipitant in the existing recovery technology, the ion exchange column is easy to pollute and block, and the treatment efficiency of low-concentration acid etching solution is low, and proposes a recovery process for cadmium telluride solar cell components method.

The present invention uses magnetic polymer microspheres to directly and rapidly enrich Cd and Te elements from the CdTe acid etching solution, and then sequentially obtains a solution containing high concentrations of Cd and Te through magnetic separation and dilute acid washing. Can be used for further electrolytic separation of Cd elements. The magnetic polymer microspheres can be reused in the above adsorption separation process after being regenerated with NaOH solution.

Firstly, the CdTe solar cell glass assembly from which the EVA encapsulant was removed was immersed in an acid etching solution containing sulfuric acid and hydrogen peroxide, and then the Cd and Te elements were enriched from the CdTe acid etching solution using magnetic polymer microspheres, and sequentially A solution containing Cd and Te was obtained by magnetic separation and dilute acid washing.

Concrete recovery process step of the present invention is as follows:

(1) First, immerse the CdTe solar cell glass assembly from which the EVA encapsulant has been removed in a compound acid etching solution of sulfuric acid/hydrogen peroxide and etch fully, and obtain an acid etching solution containing Cd and Te elements after solid-liquid separation; the obtained acid The etching solution can be used again to etch the CdTe solar cell glass assembly from which the EVA encapsulant has been removed. Among them, the dosage ratio of the CdTe solar cell glass module with the EVA encapsulant removed, sulfuric acid solution with a concentration of 1.0mol/L and hydrogen peroxide is 1kg: 478mL: 4.8mL;

(2) Next, add the magnetic polymer microspheres to the acid etching solution prepared in step (1), and after fully stirring for 10 minutes, use a magnetic separation device to separate the magnetic polymer microspheres with Cd and Te elements adsorbed on the surface, and separate The treated solution contains only Te element. The specific structure of magnetic polymer microspheres is as follows: Fe ₃ O ₄ SiO ₂ is used as the magnetic core, which is embedded in styrene-divinylbenzene copolymer microspheres, and the surface of the microspheres has sodium sulfonate groups;

(3) Finally, the magnetic polymer microspheres with Cd and Te elements adsorbed on the surface are washed sequentially with 0.1M dilute acid solution and 0.1M NaOH solution to obtain a solution containing Cd and Te elements, and the magnetic polymerization of Cd and Te elements is adsorbed After pickling and regenerating, the microspheres can be used again in the adsorption process, that is, they can be used to adsorb CdTe acid etching solution again. The above adsorption-regeneration process is repeated several times to obtain a high-concentration elution solution containing Cd and Te elements, which can be used for further electrolytic separation of Cd;

(4) In short, this process adopts the magnetic separation method to separate Cd and Te elements from the acid etching solution.

Compared with the prior art, the advantages of the present invention are: 1) The Cd and Te elements are directly enriched and removed from the CdTe acid etching solution, avoiding the difficulty in controlling the pH value of the solution and the large amount of acid and alkali solution used in the stepwise sedimentation process of the alkaline solution Disadvantages; 2) The magnetic separation process has a fast separation speed, and the metal ions can be separated from the acid etching solution in a few seconds. The regeneration process of the magnetic polymer microspheres is convenient, and the exchange column blockage in the form of an ion exchange column is avoided, and the processing capacity is small. Disadvantages; 3) Various concentrations of CdTe acid etching solutions can be repeatedly enriched by this process before the electrolytic separation process, and the process is simple and easy to scale up.

Description of drawings

Figure 1 The relationship between the concentration of Cd and Te and the etching time during the two acid etching processes of CdTe;

The influence of the amount of magnetic polymer microspheres on the removal of Cd and Te elements in CdTe acid etching solution in Fig. 2;

The removal ability of Cd and Te elements in CdTe acid etching solution by magnetic polymer microspheres in Fig. 3;

The infrared spectrum of Fig. 4 magnetic polymer microsphere;

Scanning electron micrograph and energy spectrum analysis of Fig. 5 magnetic polymer microsphere;

Fig. 6 Hysteresis loops of magnetic polymer microspheres.

detailed description

1) Immerse 1 kg of CdTe solar cell glass assembly from which the EVA encapsulant has been removed in an acid etching solution containing sulfuric acid and hydrogen peroxide. The equilibrium concentrations of Cd and Te after two times of acid etching are 2274ppm and 2720ppm, respectively, as shown in Figure 1.

2) Add the magnetic polymer microspheres into the secondary acid etching solution of CdTe, and after fully stirring for 10 minutes, use a magnetic separation device to separate the magnetic polymer microspheres whose surface has adsorbed Cd and Te elements. Investigating the removal ability of magnetic polymer microspheres to Cd and Te in 5mL CdTe secondary acid etching solution, it can be seen that: with the increase of the amount of adsorbent, the removal rate of Cd and Te is significantly improved; 100% Cd and 80% Te can be adsorbed Separation, as shown in Figure 2. After diluting the 5mL CdTe secondary acid etching solution 5 times with deionized water, add 2.5g magnetic polymer microspheres and stir for 10min to reach adsorption equilibrium; add 2.5g magnetic polymer microspheres again to the solution obtained after magnetic separation, and The process was repeated five times, and finally 100% Cd and 80% Te could be separated by adsorption, as shown in Figure 3. The treated solution only contains Te element, which can be used for re-enrichment;

There are sulfonic acid groups on the surface of the magnetic polymer microsphere, as shown in Fig. 4 and Fig. 5 . The magnetic saturation strength of the magnetic polymer microspheres can reach 8.2emu/g, as shown in Figure 6. As shown in Fig. 4, in the infrared spectrum of magnetic polymer microspheres, a group of peaks at 3033 cm ^-1 and 1596, 1500, and 1447 cm ^-1 correspond to the stretching of CH on the benzene ring in styrene-divinylbenzene Vibration peaks, two peaks at 1195 and 1045 cm ^-1 correspond to sulfonic acid groups. From the scanning electron microscope photos and energy spectrum analysis results of the magnetic polymer microspheres in Figure 6, it can be seen that the surface of the microspheres has Fe, S, Si, C, O and Na elements, which further confirms that the magnetic polymer microspheres contain Fe ₃ O ₄ SiO ₂ Core-shell structure magnetic particles, styrene-divinylbenzene polymer resin base and sodium sulfonate group.

3) Pour the magnetic polymer microspheres with Cd and Te elements adsorbed on the surface into a storage tank containing a 0.1M dilute acid solution, stir for 10 minutes and magnetically separate the regenerated polymer microspheres, and then activate the magnetic polymerization with a 0.1M NaOH solution The material microspheres are then used for the secondary acid etching solution for the next adsorption and separation of CdTe. In the dilute acid solution storage tank used to regenerate magnetic polymers, as the number of adsorption-magnetic separation-pickling regeneration increases, the concentration of Cd and Te ions contained in the eluent continues to increase, which can be used as a mother solution for further electrolytic separation of Cd elements.

Claims (2)

1. the recovery method of a CdTe solar module, it is characterized in that first the CdTe solar battery glass assembly eliminating EVA packaging plastic being immersed in the pickling solution containing sulfuric acid and hydrogen peroxide, adopt the magnetic polymer microballoon of tool enrichment Cd and Te element from the pickling solution of CdTe subsequently, and obtain by the method for Magneto separate and weak acid scrubbing the solution containing Cd and Te successively; The structure of described magnetic polymer microsphere is: with Fe ₃o ₄siO ₂for magnetic core, magnetic core is embedded in styrene diethylene benzene copoly mer microballoon, and microsphere surface has sodium group.

2. the recovery method of CdTe solar module according to claim 1, is characterized in that: the step of described recovery method is as follows:

(1) the CdTe solar battery glass assembly eliminating EVA packaging plastic is immersed in abundant acid etching in the compound pickling solution of sulfuric acid/hydrogen peroxide, after solid-liquid separation, obtains the pickling solution containing Cd and Te element; In pickling solution, eliminate the CdTe solar battery glass assembly of EVA packaging plastic, amount ratio that concentration is 1.0mol/L sulphuric acid soln and hydrogen peroxide is 1kg:478mL:4.8mL;

(2) magnetic polymer microsphere is joined in the obtained pickling solution of step (1), after abundant stirring 10min, magnetic separating device release surface is adopted to adsorb the magnetic polymer microsphere of Cd and Te element, only containing Te element in the pickling solution after separating treatment;

(3) 0.1M dilute acid soln and the 0.1MNaOH solution washing surface adsorption magnetic polymer microsphere of Cd and Te element is adopted successively; Obtain the solution containing Cd and Te element;

(4) magnetism separate method is adopted to be separated from pickling solution by Cd with Te element;

Above-mentioned absorption-Magneto separate-acid cleaning process can obtain for several times the higher elute soln of concentration containing Cd and Te element repeatedly;

Magnetic polymer microsphere in described step (3) can be recycled and reused for adsorption process after NaOH solution manipulation of regeneration.