CN-115537561-B - Method for recycling nano titanium dioxide and metal from waste LED device and application thereof

Abstract

The invention discloses a method for recycling nanometer titanium dioxide and metal bracket iron copper nickel from waste LED electronic devices, which is characterized in that waste gallium arsenide LEDs are treated by a hydrothermal-ammonia water-oxidation system, so that organic resin in the waste LEDs can be removed by oxidation, and inorganic matter in the rest LEDs is recycled. The inorganic matter is mainly iron, copper and nickel and titanium dioxide of the metal bracket of the LED. A screen is then used to separate the titanium dioxide from the metal support according to the dimensional differences between the two. And then filtering to recover the nano titanium dioxide. And finally, respectively putting the two materials into an oven for drying to finally obtain the nano titanium dioxide with the purity higher than 97% and the metal bracket iron copper nickel of the LED without impurities. The invention also discloses application of the method in recycling nano titanium dioxide and metal bracket iron, copper and nickel from waste LED electronic devices.

Inventors

• ZHAN LU
• XU ZHENMING
• ZHANG YONGLIANG

Assignees

• 上海交通大学

Dates

Publication Date

20260508

Application Date

20220916

Claims (6)

1. 1. A method for recycling nano titanium dioxide and metal support iron copper nickel from waste LED electronic devices is characterized in that hydrothermal liquid obtained after waste LEDs are treated by a hydrothermal-ammonia water-oxidation system is treated by a screen, titanium dioxide in the hydrothermal liquid is separated from the metal support, then nano titanium dioxide is recycled by filtration; the method specifically comprises the following steps: (1) Placing the abandoned LEDs into a liner of a reaction kettle, and then adding water, ammonia water and an oxidant to form a hydrothermal-ammonia water-oxidation system; (2) Placing the inner liner of the reaction kettle into the reaction kettle, sealing the reaction kettle, setting experimental parameters, starting a heating key, and waiting for the end of the reaction; (3) Sieving the hydrothermal solution obtained in the step (2) to separate iron, copper and nickel of the metal bracket from the hydrothermal solution; (4) Filtering the residual hydrothermal solution obtained in the step (3) by adopting a filtering method, and separating and enriching nano titanium dioxide from water; (5) Putting the metal bracket iron copper nickel obtained in the step (3) and the nano titanium dioxide obtained in the step (4) into an oven for drying treatment to finally obtain the metal bracket iron copper nickel without impurities and the high-purity nano titanium dioxide; In the step (1), the ammonia water is selected from industrial ammonia water containing 25% -28% of ammonia, the oxidant is selected from one or more of ozone, oxygen and hydrogen peroxide, the water is selected from one or more of deionized water, ultrapure water, tap water and groundwater, and the mass ratio of the waste LED, the ammonia water, the water and the oxidant is (0.2-4): 1-13) (100-250): 1-25; In the step (2), the reaction temperature is 180-350 ℃, the reaction time is 5-60 min, and the rotating speed of the reaction kettle is 800r/min.
2. 2. The method of claim 1, wherein in the step (3), the mesh number of the screen is 10 to 200 mesh.
3. 3. The method of claim 1, wherein in step (4), the filtering is performed by vacuum filtration.
4. 4. The method of claim 1, wherein in the step (5), the drying treatment is performed at a drying temperature of 50 to 150 ℃ for 50 to 600 minutes.
5. 5. The method of claim 1, wherein in the step (5), the impurity-free metal stent iron copper nickel has an impurity content of less than 0.1%, and the high-purity nano titanium dioxide has a purity of more than 97%.
6. 6. Use of the method according to any one of claims 1-5 for recovering nano titanium dioxide and metallic scaffolds iron copper nickel from waste LEDs.

Description

Method for recycling nano titanium dioxide and metal from waste LED device and application thereof Technical Field The invention belongs to the technical field of recovery, reuse and recycling of nanoscale inorganic fillers and metals in electronic wastes, and particularly relates to a method for recovering nanoscale titanium dioxide and metals from waste LEDs and application of the method. Background LEDs, also known as light emitting diodes, are a common type of electronic component that converts electrical energy into light energy. Its use has risen drastically in the last decade due to its energy-saving, long-life, mercury-free properties. LEDs are widely used in display screens, liquid crystal displays, cell phone backlights and general lighting. More importantly, for reasons of energy conservation, etc., legislation is being implemented in many countries and regions, incandescent lamps are phased out, and LED lamps are popularized and used, which means that the usage of LEDs in the future is inevitably increased rapidly. The waste LED mainly comprises white resin, transparent epoxy resin, a metal bracket, a metal lead and a chip. It contains noble metals such as gold and silver and strategic metals such as gallium indium, and is mainly concentrated in chips and metal leads. Meanwhile, as a new type of electronic waste, LEDs are listed as dangerous waste in parts of the european union, canada, united states, etc. As can be seen, LEDs have a potential environmental pollution risk as well as a recycling side. Therefore, it is necessary to dispose of LED waste in a green and harmless manner. There have been some studies on the recovery of metals from LEDs. Some methods of recycling waste LEDs may be referred to, such as mechanical separation, vacuum metallurgical separation, pyrometallurgy, hydrometallurgy, and bioleaching. Among the above methods, none of the other methods provides an environmentally friendly solution for decomposing the organic resin in the waste LEDs, except for pyrometallurgy. Pyrometallurgy also risks the formation of dioxins and the release of toxins during the processing of organic resins. In the past, the research on recycling of waste LEDs has mainly focused on recycling of metals, but removal of harmful substances such as organic packaging materials has been omitted. Recovery of non-metallic inorganic materials, such as inorganic fillers in resins, is also ignored. The filler TiO 2, which is a significant proportion of the LED package material, was omitted from the previous recycling process. TiO 2 is widely used as a filler material in polymer composites due to its high thermal conductivity (about 11.7W/m-K), low coefficient of thermal expansion (8.6 ppm/°C), high electrical resistivity, and non-toxic properties. The addition of TiO 2 can improve the mechanical properties and thermal stability of the polymeric material, such as tensile, flexural and dielectric strength. TiO 2 in the LED packaging material can not only improve the thermal conductivity of the resin, but also improve the reflection effect and enhance the output of LED light. Therefore, in recycling waste LEDs, a large proportion of filler titanium dioxide filler should be paid enough attention to while recycling metals. Disclosure of Invention The invention aims to solve the problems of resource waste and environmental pollution caused by improper treatment of waste LEDs, and provides a method for efficiently and environmentally recycling nano titanium dioxide and metal in LEDs and application thereof. Realizes the harmless treatment of the organic resin in the waste LEDs and the recycling recovery of the nano titanium dioxide and the metal. The hydrothermal method uses water as solvent in a closed reaction container, and is a green, nontoxic and pollution-free method. Hydrothermal processes are used to create cleaner, safer, more environmentally friendly chemical processes. It can support ionic, polar nonionic and free radical reactions. More importantly, individual water molecules can participate in the reaction as reactants or catalysts. The invention innovatively provides a method for recovering nano titanium dioxide with purity higher than 97% and metal support iron copper nickel of an LED without impurities from waste LEDs through treatment of a hydrothermal-ammonia water-oxidation system under certain conditions. According to the invention, the organic resin in the waste LEDs is removed through hydrolysis-oxidation of the hydrothermal-ammonia water-oxidation system, so that inorganic matter in the residual LEDs is partially removed. The inorganic matter is mainly the metal bracket iron copper nickel and titanium dioxide of the LED. A screen is then used to separate the titanium dioxide from the metal support according to the dimensional differences between the two. And then filtering to recover the nano titanium dioxide. And respectively placing the metal bracket iron copper nickel and titanium dioxide into