rp 450 graphite electrode
Frequently asked questions in the production of rp 450 graphite electrode
The production process of rp 450 graphite electrode in my country has been developed for more than half a century, but there is still a big gap compared with advanced foreign companies. This has resulted in an oversupply of low-end rp 450 graphite electrode on the one hand, and malicious competition from rp 450 mm graphite electrode manufacturers, which led to many rp 450 mm graphite electrode manufacturers struggling to survive; on the other hand, more than 80% of my country’s Large-scale ultra-high-power rp 450 graphite electrode used in large-scale DC electric arc furnaces have to be imported from abroad at a high price.
The development of the production industry of rp 450 graphite electrode in Ulan Qab lags far behind the requirements of the industry using rp 450 graphite electrode. Even with ordinary power rp 450 graphite electrode, there are still many problems in the production process, such as low yield, high production cost, and poor use effect. Especially when the rp 450 graphite electrode industry is at a low point, it is necessary to explore the problems and improvement measures in the production process. This article mainly analyzes and summarizes the problems existing in the production process of some small and medium-sized enterprises. 1 Problems and gaps 1.1 Raw materials There is objectively a gap in the raw materials used in the production of ultra-high power rp 450 graphite electrode in China. In foreign countries, whether it is Japan or the United States, the source of raw materials for the production of stone rp 450 graphite electrode is stable. reliable quality.
Due to the supply of needle coke in China, manufacturers of rp 450 graphite electrode have to frequently change suppliers and raw material ratios. Moreover, there is still a certain quality gap between domestic needle coke and imported needle coke. From a subjective point of view, domestic manufacturers of ultra-high-power rp 450 graphite electrode, from the perspective of reducing costs, mix lower-priced Daqing petroleum coke or Fushun petroleum coke, and even other petroleum coke. What’s more, individual manufacturers do not use granular needle coke when producing ultra-high-power rp 450 graphite electrode. At best, it increases the number of dipping. Using such rp 450 graphite electrode to pretend to be ultra-high-power rp 450 graphite electrode is inevitable. This leads to price chaos in the market, seriously jeopardizing the interests of many manufacturers. The production of ordinary power rp 450 graphite electrode also has raw material problems.
Especially for the production of rp 450 graphite electrode with steps of 500mm and less than 600mm, when selecting raw materials, Daqing or Fushun petroleum coke, which is easy to graphitize, is usually selected. However, in order to reduce costs, many domestic small and medium-sized enterprises choose Huludao coke or worse petroleum coke as raw materials, and a large amount of waste products will appear in the production process, which will eventually cause problems such as high consumption and dropout when users use it. 1.2 Adhesives rp 450 graphite electrode produced abroad use special rp 450 graphite electrode asphalt. Domestic asphalt manufacturers have also produced modified asphalt with continuous efforts. Many manufacturers have used rp 450 graphite electrode to achieve the quality of rp 450 graphite electrode. Improve, but there is still a process to popularize and promote. Many manufacturers do not pay much attention to the binder, and some manufacturers only stay at the softening point of coal tar pitch, and do not check other indicators. In the production process, the binder only melts, and there is no standing process, so a lot of waste products will inevitably appear in the molding and roasting process.
(1) Due to problems in the selection of vibrating screens or screens, the purity of the particles is very low. Many manufacturers have only 50% ~ 60% of the particle purity, so there is a big difference in the particle material between the pan and the pan, and it is difficult to guarantee the paste. The stability.
(2) Many manufacturers have not yet used electronic scales for ingredients, and there are too many artificial factors in the ingredients, resulting in large differences in the plasticity and particle size composition of the paste between the pan and the pan.
(3) The amount of ingredients is too large. Because workers are paid according to output, many manufacturers blindly add more ingredients regardless of the optimal output of the kneading pot and the maximum output of the kneading pot. During the production, the material on the kneading pot does not move, and the dry material is mixed in the middle when the paste is discharged. The quality of the green body is of course not guaranteed.
(4) The powder is too fine. Many manufacturers still use powder with a purity of 75% or even 80% or more; the powder is not standardized during sieving analysis, and the powder samples taken are not dried. Some manufacturers even use glass balls for sieving. No, these will cause the powder used in production to be too fine. Moreover, it is difficult for domestic kneading pots to mix the fine powder uniformly. The use of fine powder not only has a low yield in the molding process, but also has a low yield in roasting and graphitization, and ultimately consumes a lot of money when used by users.
(5) Unreasonable use of dust collection powder. First, the dust collection powder is too fine, and the other is the content of impurities. Many large factories use dust collection powder for other purposes in the production process, especially not in ultra-high power and high power; even if it is used in ordinary rp 450 graphite electrode, it should be added uniformly instead of added. If it’s gone, don’t add it, or directly discharge the dust collection powder into the powder. The powder and dust collection powder are mixed together very unevenly; if the amount of dust collection powder exceeds 7%, the quality of the green body will be affected. .
(6) The rationality of the granularity of the formula. In recent years, domestic professional and technical personnel have done a lot of work on the particle size composition of the formula, and the concept of the large-particle formula is highly respected. Industry groping summary.
(1) Mixing of wet materials. Even if the needle coke that has just come in by many foreign manufacturers, the 800T secondary calcination is carried out to discharge the water in the needle coke. However, many domestic manufacturers do not have warehouses and silos for storing dry materials. Dry materials are stacked in the open air, which will not only absorb moisture in the air, but will get severely exposed to rain. During dry mixing, there are obvious water vapor and water droplets in the observation port on the top of the kneading pot. It is more difficult to drain all the moisture in the raw materials only by dry mixing. If water remains in the raw materials, the penetration of asphalt will be affected when asphalt is added, and the kneading effect will be greatly reduced.
(2) Unreasonable heat transfer oil pipe network system and mixing temperature. In order to save money, many small and medium-sized enterprises do not hire professionals to design the production process, but design, manufacture, and install themselves. In particular, the heat-conducting oil pipe network system simply connects the pipes for granted, and the heat-conducting oil runs in the pipes, which cannot directly reflect the temperature distribution in the entire pipe network. It is inevitable that the temperature of several kneading pots is different, and the temperature is constantly changing, and the kneading time is consistent according to the process requirements, which will inevitably lead to a large difference in the temperature of the paste. Individual companies do not set the process temperature first, but the process temperature adapts to the production conditions. The heat-conducting oil furnace is too small, the calcining residual heat is too little, etc. The outlet temperature of the heat-conducting oil is only about 150T, and even lower ones, which are also forced to produce. The paste temperature is only about 120T, but the asphalt softening point is 87~90X. , The plasticity of the paste must be very poor.
(3) The dry mixing time is too long, and the particle size composition of the raw materials is destroyed. The importance of dry material heating is recognized by more and more people, but the dry material heating must be under the premise that the particle size of the material is not broken. . In order to increase the dry mixing temperature, many companies do not add a dry material heater to the kneading pot, but rely on extending the dry mixing time, and some even extend the dry mixing time to more than 1 h. Although the dry material temperature has been increased to a certain extent, At the same time, the particle size composition of the raw materials is also destroyed.
(4) The distance between the stirring knife and the bottom of the pot is too large or too small. The distance between the stirring knife and the liner should be determined according to the particle size of the product produced, not more than 30mm as generally stated in many books. Many companies bought the kneading pot for four or five years, and did not check the wear of the stirring knife and the liner. Because the distance between the stirring knife and the liner was too large, the kneading effect became smaller, causing uneven mixing and pinching. Dry material phenomenon; when some companies repair the kneading pot, the distance between the stirring knife and the liner is smaller than the maximum particle size of the ingredients, and the large particles are ground, which changes the particle size composition of the material.
(5) The raw fragments are too large. Many companies have only one-stage jaw crushing during raw crushing. After crushing, the particle size of the raw crushed pieces is about 50mm. It is difficult to integrate them with the paste during the mixing and kneading process, and eventually they will fall off when the product is used.
(6) Add too much adhesive. Although increasing the amount of binder, the fluidity of the paste becomes better, and the molding process is easy to shape, but the rate of roasting waste also increases. Not only will the roasting process bring hidden dangers of empty and deformed waste products, it will also cause the bulk density and strength of the final product to decrease.
(1) Cylindrical cooling material, large and small spheres are formed in the cooling material process, and the interface between the ball and the ball will always appear during the molding process. If the blanking temperature is lower, there will be many structural cracks inside the rp 450 graphite electrode. There are even spherical blocks in the finished rp 450 graphite electrode, and the blocks will eventually fall off when the user uses them.
(2) Disc cooling material, the longer the cooling material process time, the greater the temperature difference, and the poorer the plasticity of the paste. However, the bitumen flue gas cannot be discharged after the time is short, resulting in increased opportunities for product defects in the subsequent process.
(1) Extrude large-size products with a small press. Because some small and medium-sized enterprises do not have large presses, they use small presses to forcibly produce large-size products. Everyone knows that in the production of a large press, a part of the mouth with a bad structure should be cut off, while a small press has a small material chamber, and a total of one or two products can be produced, so basically two pots of paste are connected. The internal structure of the product and the green body is also relatively poor, and it is inevitable that the product will break in the later process and when the user uses it.
(2) No vacuuming. Vacuuming is beneficial to exhaust the bituminous gas in the paste, so the temperature can be slightly higher when the material is cooled, which is convenient for forming and increasing the bulk density of the green body. The presses used by many companies are too simple and do not require vacuum.
(3) No synchronization cut. There are many small cracks in the produced product from 300mm to 500mm from the end. The rp 450 graphite electrode are processed into finished products, which are just at the bottom of the rp 450 graphite electrode. The rp 450 graphite electrode are often used here. fracture.
(4) The inner lining was not replaced in time after it was worn out. After several years of use of the press, the inner lining has worn out, and the distance between the pressing ring and the inner lining has increased. During pre-pressing, the paste is extruded from between the pressing ring and the inner lining, and the thickness may reach 30-50 mm. The machine is difficult to maintain pressure, and the paste is difficult to be compacted in the chamber.