Waste PCB board crushing and recycling production line
A new type of waste circuit board recycling process and equipment with strong applicability and high environmental protection. The production line is a fully automatic production line and adopts advanced physical recycling technology. It can effectively carry out mechanical crushing and recycling of all kinds of waste printed circuit boards, processing waste, waste electrical appliances, etc. The metal recovery rate is high, and the purity of the recycled metal is as high as 98%.
Waste printed circuit boards are a mixture of glass fiber reinforced fat and various metals, which are typical electronic waste. The metal grade in the circuit board is equivalent to tens to hundreds of the metal grade in ordinary minerals, and the metal content is high. Up to 40%, most of them are copper, in addition to gold, aluminum, nickel, lead, silicon, etc., among which there are many rare metals; and the content of rich ore metals in nature is only 3%-5%. If it is not properly handled and disposed of, it will not only cause a large loss of useful resources, but also contain a large number of teratogenic, mutagenic, and carcinogenic substances such as cadmium brominated flame retardants, which will cause serious environmental and human health. A highly environmentally friendly and efficient fully automated recycling and processing waste circuit board production line suitable for my country’s national conditions.
Whole line composition and process flow
The circuit board recycling and processing production line is mainly composed of conveyors, primary crushers, secondary crushers, magnetic separators, crushers, sorters and other auxiliary equipment. Its technological process is shown as in Fig. 1. After the discarded circuit boards are manually dismantled, the harmful electrical components such as batteries, transformers, etc. and reusable parts are removed, and the remaining part is sent to the first-stage crusher via a scraper conveyor to crush the material to less than 20mm , And then sent to the secondary crusher to crush the material to less than 5mm, the iron-containing material is separated by the magnetic separator, and the remaining material is crushed to the powder of about 2mm by the crusher, so that the copper in the multilayer machine board can be separated , The light dust is separated first by winnowing, and the materials with larger specific gravity are sent to the electrostatic separator to separate and recover about 20% of the non-ferrous metals (copper, etc.).
The circuit board has high hardness and good toughness: it has good bending resistance; most of it is flat, it is difficult to separate metal and non-metal through one-time crushing; it contains many kinds of substances, and the metal is entangled after dissociation, etc. . The first-stage crusher uses a double-roller shearing method to cut large pieces of discarded circuit boards. It is mainly composed of driving body, spline shaft (knife shaft), blade, sparse plate, frame and other components. Among them, the spline shaft (knife shaft) and the blade are the key components to ensure the coarse crushing process. The PCB is crushed to 20 mm and sent to the secondary crushing. The spline shaft (knife shaft) can optimize the power transmission of the blade. Through special heat treatment and ultrasonic testing, the blade and the distance ring can be easily removed for easy replacement of the blade. The blade is made of forged high-alloy steel material and is made through multiple heat treatments and finishing. The sparse plate is made of highly wear-resistant stainless steel. It plays a role in guiding materials, cleaning the blades, and preventing material recovery after crushing.
Secondary crushing (fine crushing) process:
The secondary crusher (fine crusher) crushes materials with a particle size of 20 mm. The technology used is a mixed crushing method of rotary shearing and hammering to perform secondary crushing of materials of a certain size. Whether the particle size after crushing meets the technological requirements depends on the structural shape of its rotating body, movable knife, static knife, sieve plate, frame and other components. The movable knife is connected with the revolving body and adopts special tool steel with surface treatment, which is convenient for replacement and maintenance. The static knife is connected with the frame, and the particle size of the crushed material is restricted by adjusting the distance between the moving knife. The sieve plate is made of wear-resistant steel plate, and the sieve holes on the sieve plate can define the particle size of the discharged material.
Magnetic separation process:
The machine is mainly composed of magnets (coils, outer iron yokes), a sorting box equipped with magnetic media and supporting structures, and material flow distribution. Equipped with a variety of vibrating feeders suitable for uniform feeding of thin layers of different materials. It is used for the abundance of the magnetic separator in the electrical waste sorting process. Its main process is to separate the iron parts from the waste. The magnetic circuit design of the equipment is novel, the sorting efficiency is high, the sorting magnetic field strength is not less than 1.2T, the magnetic field strength can be adjusted freely, and the iron-containing parts in the garbage can be effectively sorted out. The magnetic roller is protected by the transmission separation belt, and it is not easy to demagnetize without wear. The surface of the cylinder adopts special wear-resistant materials as a protective layer to avoid the wear of the cylinder: simple and practical self-weight flat tape tension and correction mechanical device: high-strength ultra-thin (l mm) conveying and sorting tape.
Density screening process
In the case of the same material particle size, the materials with different densities in the mixture can be separated by the vibration and air separation process. The sorting is carried out in a closed cavity, so there is little environmental pollution, and the technology is mature, and the sorting effect is good.
Pulverizer crushing process
The pulverizer is to pulverize materials with a particle size of about 5mm into fine particles of about 2 mm, which can separate the pot in the multilayer machine board, and lay a good foundation for effectively sorting out the non-ferrous metal copper in the waste circuit board. . The process is similar to that of the =-grade crusher, except that the screen is more dense. The number and wear resistance of movable knives and static knives are better than those of the secondary crusher.
Electrostatic separation process
It uses the principle that substances with different conductivity enter the electric field and all obtain negative charges, but their behavior in the electric field is different to realize the sorting. The material with good conductivity quickly transfers the negative charge to the positive electrode without being affected by the positive electrode. Materials with poor conductivity transfer charges very slowly and are attracted by the positive electrode. Thus the material is divided into three parts: conductor, semiconductor, non-conductor. The realization of its craft depends on its special structure. The maximum outer diameter of the roller is selected. The size of the outer diameter directly affects the sorting quality. The larger outer diameter has a good sorting effect, and the larger outer diameter affects the leveling of the roller. Usually, the outer diameter of the roller is 300mm. The selection and matching of high-voltage power supplies are the key.
The quality and reliability of the electrostatic sorting machine directly affect the overall performance of the corona electric field. The center distance of the electrodes is about 150 mm, and the voltage is (35-50) kV, which can form a wide corona electric field. The arc electrode power supply It is a negative high voltage power supply. The power supply adopts self-adaptive regulation technology, always working in the critical state of driving, providing corona power and obtaining good efficiency. The sorting rate depends on the quality of the electric field and the particle size and humidity of the materials. The dry loose materials with a particle size of (2 -0.2) mm are sorted through experiments. Through one sorting, 20% of metal conductors and 60% of non-metallic materials can be obtained. conductor.