Non-ferrous metal scrap pretreatment refers to non-ferrous scrap and scrap state becomes possible to effectively process subsequent metallurgical processes. This process includes: achieving various physical dimensions and weight standards for various waste materials and waste materials; separating non-ferrous metals from ferrous metals; removing non-metallic inclusions, moisture, oil, and the like. Fine and high-quality preparation of waste non-ferrous metals, suitable for metallurgical processes, can reduce the loss of non-ferrous metals to a minimum, reduce the unit consumption of fuel, electricity and flux, and make efficient use of metallurgical equipment and transportation tools. And improve labor productivity and the quality of non-ferrous metals and alloy products.
Pretreatment of non-ferrous metal scraps and scraps includes the following main processes: sorting, cutting, packing, briquetting, crushing, grinding, magnetic separation, drying, degreasing, etc. Special recycled raw material (waste battery, motor waste, scrap wire, scrap iron horse) pretreatment, using a special production line.
The All-Russian Recycling Non-Ferrous Metals Scientific Research Institute has studied the general process flow of waste non-ferrous metal pretreatment (Fig. 1), starting from non-ferrous scrap and scrap into the workshop, and until the finished product is sent to the customer's plant.
Waste chip processing
Waste chips are produced by metal cutting machines that process non-ferrous metals and alloys. The chemical composition of the alloy is different from the cutting tool used, and the shape and size of the individual particles of the nonsense chip are also very different. Waste chips are divided into loose chips and rolled (spiral) chips, coarse and fine chips, homogeneous chips and mixed chips. In the process of machining the blank, there will be mechanical inclusions of iron in the scrap, and the iron content can reach 30%. The processing of waste non-ferrous metals and alloys on machine tools using lubricated coolants also results in the storage of emulsions and oils in the waste chips. If waste chips are stored in the open air, the moisture and oil content can reach 20-30%. The wet chips will corrode quickly and the alkaline emulsion will accelerate the corrosion process. In order to achieve high technical and economical indicators in the metallurgical processing of waste chips, mechanical impurities of iron and moisture, oil and sand must be removed from the chips. To this end, the waste chips must be crushed, dried, and then sieved and magnetically selected.
The crumb breaking is performed by a chip unit based on a hammer crusher . The chip unit (Fig. 1) consists of a modified CM-2 hammer crusher (Fig. 2) and a feeding device, a tearing device and a belt conveyor. The rolling debris is towed from the receiving bin to the belt conveyor by the claw wheel of the tearing device. During this process, the crumbs are torn into small bundles and partially broken. Next, the coiled chips are fed into the loader of the crusher by the belt conveyor, and are pulverized and sprinkled under the impact of the rotary hammer into the hopper of the belt discharge conveyor. The claw wheel of the tearing device was rotated at 18 rpm, and the rotor speed of the crusher was 750 rpm. The processing capacity of the CДA-7 chip unit can reach 10 tons/hour.
Figure 1 CДA-7 type chip unit
1-receiving bin; 2-tear device; 3-claw wheel; 4-belt conveyor;
5-hammer crusher; 6-grid sieve; 7-hammer; 8-cover; 9-block leak nozzle; 10-rotor
Figure 2 CM-2 hammer crusher
1-chamber; 2-rotor; 3-hammer wheel; 4-armored plate; 5-pitch adjuster; 6-grid screen
(Previously) Many regenerative non-ferrous metallurgical enterprises in the Soviet Union used the assembly line equipped with (former) West Germany Becker equipment (Fig. 3) to process waste chips. The line includes: a drum screen with a diameter of 3000 mm, a length of 6000 mm and a screen diameter of 50 mm, a drum screen for sorting magnetic components, measuring 700 × 3000 mm, and a cutting machine (tearing Device). The cutting of the rolling chips is carried out in batches by the cutting machine (the maximum size of the cutting chamber is 2800×2000×1000 mm, the stroke of the piston is 2800 mm, the thrust is 2500 kN), and a batch of coiled chips is up to 600 mm long and 400 mm wide. 250 mm. After the cutting process, unsmashed large pieces of material must be manually picked from each batch of waste chips and collected into separate bins.
Figure 3 Schematic diagram of the waste chip processing line using Becker equipment
1-grab; 2-roller screen; 3-magnetic plate; 4-cutting machine (tear device);
5-hammer crusher; 6-belt conveyor; 7, 8-plate conveyor
The waste chips were fed by a slab conveyor into a hammer crusher with a rotor speed of 16.3 rpm. The crushed waste chips have a particle size of 0 to 40 mm. Treatment of the aluminum alloy of the pipeline capacity is 3-5 tons / hr. Such pipeline processing is also applicable to a copper base rolled alloy chip.
The subsequent treatment of the waste chips after the crushing is carried out on the degreasing and drying lines. Degreasing can be carried out by water chemistry, mechanical methods and thermal methods.
The water chemical method removes oil, and the waste chips are washed in a spiral mixer or a centrifuge with an alkaline solution of heat (60 to 80 ° C). After removal of the solution, the moisture and oil in the crumb did not exceed 0.2%. After separating the solid particles from the oil, the solution is returned to the process for use. The waste chips that have been degreased can be sent for metallurgical treatment.
The water chemical degreasing process has not yet been widely used, and the method is suitable for treating valuable waste chips which are produced in a small amount.
Mechanical degreasing is carried out using a variety of intermittent and continuous motion centrifuges. In a circulating centrifuge, waste chips are loaded when the rotor rotates at a falling frequency or a stopped state. After the loading is completed, it is automatically changed to high speed. Automatically switch to high speed. After the oil is removed, the rotor is braked, and the waste chips are discharged into the feeder by gravity, and then the rotor is under-washed by the compressed air. The waste chip handling capacity of the centrifuge is 1.0 to 1.5 tons per hour.
In a continuous centrifuge, waste chips are thrown onto the rotor wall and squeezed. At the same time, the centrifugal force moves the waste chip particles along the rotor wall to the discharge end. The processing capacity of such a centrifuge can reach 7.5 tons / hour, and the lubrication in the chips makes the residual content of the liquid below 2 to 4%.
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