In the iron and steel smelting process, due to improper ingredients or improper loading and excessive decarburization, the carbon content in steel or iron sometimes fails to meet the expected requirements, and carbon is added to steel or molten iron. The main substances commonly used for carbon addition are anthracite powder, carbon-increasing pig iron, electrode powder, petroleum coke powder, pitch coke, charcoal powder and coke powder. The requirement for recarburizer is that the higher the fixed carbon content, the better, and the lower the content of harmful impurities such as ash, volatile matter and sulfur, the better, so as not to contaminate the steel.
The smelting of castings uses high-quality recarburizer after high-temperature burning of petroleum coke with little impurities. It is also the calcined coke that I often say, which is the most important part of the carbon-increasing process. The quality of the recarburizer determines the quality of the molten iron and determines whether it can achieve good graphitization. In short, reducing the shrinkage of the molten iron recarburizer plays a pivotal role.
In the smelting of the whole scrap electric furnace, the graphitized recarburizer is preferred. After the high-temperature graphitization of the rebcarurizer, the carbon atoms can be changed from the original disordered arrangement to the sheet-like arrangement, and the flake graphite can become the best of the graphite nucleus. The core is to promote graphitization. Therefore, in pursuit of high quality requirements, we should use a high-temperature graphitized recarburizer. Because of the high temperature graphitization treatment, sulfur is reduced by the generation of S02 gas. Therefore, the graphitized rebcarburizer has a very low sulfur content, w(s) is generally less than 0.05%, and better w(s) is even less than 0.03%. At the same time, this is also an indirect indicator of whether or not high temperature graphitization and graphitization are good. If the selected recarburizer is not subjected to high temperature graphitization, the nucleation ability of graphite is greatly reduced, the graphitization ability is weakened, and even if the same amount of carbon can be achieved, the result is completely different.
The so-called rebcarurizer is to increase the carbon content in the molten iron after the addition, so the fixed carbon content of the recarburizer must not be too low, otherwise it is necessary to add more than the high-carb recarburizer to achieve a certain carbon content. The sample, which undoubtedly increases the amount of other unfavorable elements in the recarburizer, does not allow the molten iron to obtain better yields.
The low content of sulfur, nitrogen and hydrogen is the key to prevent the formation of nitrogen pores in the casting, so that the lower the nitrogen content of the recarburizer, the better. Other indicators of recarburizer, such as the lower the amount of moisture, ash, and volatile matter, the higher the fixed amount of damage, so the high fixed carbon content, the content of these harmful components must not be high. It is also important to select the appropriate recarburizer particle size for different melting methods, furnace types and size of the melting furnace. It can effectively increase the absorption rate and absorption rate of the recarburizer by the molten iron, and avoid the increase due to too small particle size. The agent is oxidized and burned. The particle size is preferably: 100 kg furnace is less than 10 mm, 500 kg furnace is less than 15 mm, 1.5 ton furnace is less than 20 mm, and 20 ton furnace is less than 30 mm. In converter smelting, when high carbon steel is used, a recarburizer containing little impurities is used.
The requirement for recarburizer for top-blown converter steelmaking is that the fixed carbon is high, the ash, volatiles and sulfur, phosphorus, nitrogen and other impurities are low, dry, clean and moderately sized. Its fixed carbon C>97%, volatile matter <1.0%, S<0.5%, moisture <0.5%, particle size in l-5mm. The particle size is too fine to be easily burned, and when it is too thick, it floats on the surface of the molten steel and is not easily absorbed by the molten steel. For the induction furnace, the particle size is 0.2-6mm, wherein the steel and other ferrous metals have a particle size of 1.4-9.5mm, the high carbon steel requires low nitrogen, the particle size is 0.5-5mm, etc., and the specific need to smelt the workpiece according to the specific furnace type. The specific types and details of the specific judgment and selection.
The mainstream prices of China's carburizing products are stable and the market is better. The market commencement rate of the universal calcining agent is still low, and the environmental supervision group in Ningxia area has not been evacuated in the main production area. The enterprises are mostly building the closed raw material warehouse and upgrading the environmental protection equipment, actively realizing the emission standards, and the heavy rain raids, the market shipment is limited, but the market price is affected by the acceptance degree and demand of the next tour. Fluctuation. The market price of calcined coke and graphitized carburizing agent changed little, and the whole was relatively stable.
Coal carburizing agent of common calcined coal: this week, the mainstream price of China's universal carburant market is stable, environmental pressure in Ningxia is dependent, market start rate is low, enterprise shipping transportation is better than that of heavy rain weather last week. At present, enterprises are mostly in maintenance, environmental protection equipment upgrading and upgrading, and the control of dust leakage is more strict in the area. However, the price of raw material calcined anthracite is stable, the price of carburizing agent is no good support, the second carburizing agent in the lower reaches of the market is normal, the enterprises are many old customers, the market demand is stable, and the price is stable this week. The production in Hebei area is normal, but the local truck management is strict.
Calcined coke coke increased: this week, the market price of calcined coke carburant is stable and the market is stable. The price of high sulfur calcined coke in raw materials is stable, and enterprises have no intention to adjust. Enterprises in Henan have not yet started operation because of environmental protection. Jiangsu area is still limited by 50% in this week. One enterprise has stopped working this week; most of the Hebei regions signed a monthly contract. This week the enterprises started to start smoothly. The enthusiasm of the steel plant is general, the calciner is produced by a few negative enterprises, and the individual steel plants choose the low price of the universal calcining agent, and the calcining carburizing agent is reduced to the foreign supply. Commonly used specifications for calcined coke coke increasing enterprises.
Graphitized petroleum coke carburizer: This week, the price of graphitized petroleum coke carburizer is stable, the market is abundant, the shipment situation is general. In addition, the graphitization of negative materials in the market will be put into production in the second half of the year, and the output is expected to be released in succession, affecting the overall supply of the graphitized carburizing agent market.
The concentration of negative enterprises in Inner Mongolia area is high, and the graphitization carburizing processing enterprises are also gradually switching to the market, and the market concentration is increasing. Jiangsu started normal operation, good delivery, orders are mainly old customers. Negative material processing enterprises in Qinghai, Lanzhou, Ningxia, Inner Mongolia and other regions have higher activity and higher output. It is understood that at present, the demand for foreign goods is increasing and demand is increasing. Graphite carburizing agent to Tianjin port price C>98.5; S<0.05; <0.8%, VM<0.7% 1-5mm, if Ningxia area environmental protection continues to force, the market start rate is declining, and spot stock consumption to low, or will drive the market price of carburized carburizing agent. It is estimated that the market price of general calcined carburizing agent may be upward, and it is expected to increase at 100 yuan / ton.
Name: Owen Zhang
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