A recycling method for waste varistors

Abstract

The invention discloses a resourceful treatment method for a waste piezoresistor and belongs to the technical field of resource utilization of electronic waste. According to the technical scheme, the resourceful treatment method for the waste piezoresistor comprises the steps of removing insulating paint skin with solvent mixed flow; removing nickel-iron alloy wires and soldering tin through low-temperature liquid nitrogen refrigeration and mechanical collision; and recycling silver scraps through high-temperature scraping and reciprocating sieving. In the resourceful treatment process of the waste piezoresistor, no incineration pollutant or acid-containing waste water or waste water containing heavy metal ions or waste residue is discharged; in addition, fuel combustion for energy supply is not needed in the whole process; energy conservation and environment protection are achieved to a greater extent; in addition, the refining degree, the comprehensive output value and the input-output of the process are far above those of traditional treatment processes.

Description

technical field [0001] The invention belongs to the technical field of resource utilization of electronic waste, and in particular relates to a method for resource recovery of waste varistors. Background technique [0002] A varistor is a resistive device with nonlinear volt-ampere characteristics. Its structure is usually silver-plated on both sides of a smooth high-temperature sintered ceramic substrate, and then copper-plated iron-nickel alloy wires are welded on both sides by electronic soldering tin, and then painted. Apply a layer of polymer insulating paint. Due to its good nonlinear volt-ampere characteristics, the varistor has no discharge gap. When the overvoltage is applied, the resistance drops sharply, and the overvoltage energy is released to achieve the protective effect. [0003] Varistors are disposable consumables for power electronic components. Since their invention, they have been widely used in power supply systems, motor protection systems, automotive...

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Problems solved by technology

[0005] There are many disadvantages in the above process: the method of incineration to remove insulating paint has long been banned by the environmental law enforcement department of our country, and a large number of incineration operations are illegal or even criminal; the removal of solder at high temperature is usually done by direct heating, baking or even burning and frying. This method is simple and extensive, the removal of solder is insufficient, and silver is also lost; silver pickling is carried out with waste nitric acid from the factory, and sodium chloride is used as the precipitant. The crude silver obtained is filtered through the plate frame and then burned to obtain Coarse silver, this process will produce a certain amount of acid wastewater containing heavy metal ions, nitrogen oxides, hydrogen chloride, etc., which will endanger the health of operators and seriously pollute the surrounding environment

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