1. chemical method: the process of extracting metals by using the stability of various chemical components in waste circuit boards.
Incineration method: organic components are incinerated at high temperature, and then the remaining metal substances are recovered, but a large amount of organic waste gas and toxic substances will be produced, which will pollute the environment.
Microwave treatment: the waste circuit board is heated to about 1400℃ by microwave. After cooling, metals such as gold and silver will be automatically separated in the form of beads, and the remaining glass can be used as building materials.
Hydrometallurgy: Using the characteristic that metals can be dissolved in acidic solutions such as sodium cyanide, hydrochloric acid, sulfuric acid, etc., metal substances in waste circuit boards can be recovered, but the chemical waste agent produced in the process will pollute the environment.
2. Dry physical method: firstly, the waste circuit board is crushed into powder, and then it is sorted according to the weight and conductivity of metal and nonmetal, which has high treatment efficiency and no pollution to the environment.
3. Biological method: The other metals in precious metal alloy are oxidized into soluble substances and dissolved in the solution by the oxidation of ferric ions, and the exposed precious metals are recovered. However, bioleaching takes a long time and has low efficiency, so it has not really been put into use at present.
Recovery and treatment method of waste circuit board
Among them, mechanical treatment is a common method in the industry. Mechanical treatment is an effective method to pre-separate different components of waste circuit boards. The process is divided into three steps: disassembly, crushing and classification.
(1) Dismantling is mainly to remove the electronic components on the circuit board.
(2) Crushing is to crush the circuit board substrate into particles or powder, and the particle size varies according to different crushing methods.
(3) The main method of sorting is to use the differences of physical properties between substances, such as density, magnetism, electricity, surface properties and optical properties.