Graphite electrode is an important high-temperature conductive material for electric furnace steelmaking. With the development of electric furnace steelmaking technology, new requirements are put forward for the variety and quality of graphite electrodes. It is an important task for China’s carbon industry to produce high-quality, large-size UHP Graphite Electrode with a diameter of 600-700mm as soon as possible. Free to get the price of the UHP graphite electrodes from Rongsheng Supplier.
Development of High Power and Ultra High Power Steelmaking Technology
The large-scale electric furnace is manifested in the increase of the average furnace capacity of the electric furnace. Many foreign electric furnace steel plants have dismantled old small and medium-sized electric furnaces through technological transformation and set a modern large electric furnace of 80-150t in a steelmaking workshop as the standard. And most steelmaking workshops separate melting and refining. In addition, a refining furnace (also an electric arc furnace) with a corresponding capacity is added, and the molten steel is poured into the refining furnace for composition adjustment after melting, so the production efficiency is greatly improved.
In the mid-1980s, ordinary power electric furnaces in industrially developed countries were basically eliminated. In the United States, Japan, Britain, Germany, and Italy, ultra-high power electric furnaces account for more than 50%. The rest are high-power electric furnaces. The capacity of transformers per furnace capacity has been continuously improved. In the early 1980s, foreign ultra-high power electric furnaces reached 600-800kV·A/t. In the mid-1980s, it was increased to 1000kV·A/t. In the late 1980s, ultra-high power electric furnaces of 1100～1200kV·A/t appeared. Therefore, the melting time of each furnace is continuously shortened, the power consumption is reduced, and the unit consumption of the graphite electrode is correspondingly reduced.
Specifications of UHP Graphite Electrodes
In terms of variety, electric furnace steel mills will gradually reduce their demand for RP graphite electrodes, and the demand for HP and UHP graphite electrodes will increase accordingly. By the Rongsheng Manufacturer, From the point of view of specifications, the demand for small and medium specifications, that is, the demand for graphite electrodes with a diameter of 400mm and below has been continuously reduced. The demand for graphite electrodes with large specifications, that is, 450mm in diameter and above, will increase year by year. After 1995, the proportion of UHP Graphite Electrode with a diameter of 600-700mm will increase significantly.
Application of UHP Graphite Electrode
Graphite electrodes are not only widely used in electric furnace steelmaking. Some ferroalloys (such as low-carbon ferrochrome) are also produced in electric arc furnaces. There is also a considerable part of graphite electrodes used in the production of industrial silicon, yellow phosphorus, abrasives, and other industries. In particular, the production of yellow phosphorus in electric furnaces in China has developed rapidly, and some electric furnaces that produce yellow phosphorus also use large-scale HP or UHP Graphite Electrode. The production of cemented carbide quartz glass also consumes a certain amount of graphite electrodes.
Inspection Index of UHP Graphite Electrode
HP and UHP Graphite Electrodes pass a higher current density when used, and the electrodes operate under more severe conditions. At present, the current density of large-size electrodes is between 18~24A/cm2, which is called an HP graphite electrode. The electrode passing the current above 24A/cm2 is called the UHP Graphite Electrode. Therefore, the physical properties of ultra-high-power graphite electrodes must be better than those of ordinary power graphite electrodes. Among the seven analysis and inspection indexes of graphite electrodes, resistivity, flexural strength, and elastic modulus are listed as quality evaluation indexes. Ash content, true density, bulk density, and compressive strength are four reference indicators. In addition, the oxidation resistance, thermal expansion coefficient, and thermal conductivity of the graphite electrode are measured as the supplier to accumulate data.
Annual Consumption of UHP Graphite Electrodes
The growth in demand for high-power graphite electrodes is closely related to the development of electric furnace steelmaking. This requires the carbon industry to provide large-scale high-power and UHP Graphite Electrodes. Due to the continuous improvement of the quality of graphite electrodes and the development of direct current furnaces, the total demand for graphite electrodes will not increase significantly.
If the annual output of electric furnace steel reaches 30 million tons, the average unit consumption is 5kg, and the annual consumption of graphite electrodes is 15 million tons. When the average unit consumption is 4.5kg, the annual consumption of graphite electrodes is 135,000 tons. In Japan in the late 1980s, the electrode consumption of electric furnace steel was reduced to about 3kg. However, due to the increasing proportion of high-power and ultra-high-power electric furnace steelmaking. Therefore, it is estimated that 40,000 to 50,000 tons of high-power graphite electrodes, 30,000 to 35,000 tons of UHP Graphite Electrodes, and large-size electrodes with a diameter of 500-600mm will rise to about 35% each year. Large electrodes with a diameter of 700 to 800 mm required for an ultra-high power DC electric furnace of about 150 tons will also be used. In addition to the electric furnace steel industry, the total annual consumption of graphite electrodes in other industries is estimated to be 60,000 to 80,000 tons, of which some are high-power graphite electrodes.
Problems Encountered in the Use of Graphite Electrodes
In the actual use process, the product quality of graphite electrodes is not satisfactory, mainly in:
(1) The joint is easy to break. As a result, the furnace shutdown time in the operation of the electric furnace is increased, and the unit consumption of the graphite electrode also increases;
(2) Poor quality stability. Not only is the deviation of the physical and chemical indicators in each batch of products large, but also the yield of the production plant fluctuates greatly. UHP Graphite Electrodes with a diameter of over 600mm are gradually being produced and applied to steel plants in China with the advancement of technology. Solved the problem that China’s high-quality electrode production lags behind the development needs of electric furnace steelmaking.
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Rongsheng Graphite Electrode Supplier
Because HP and UHP Graphite Electrodes require higher bulk density, graphite electrode manufacturers are required to use coal pitch with higher coking residual carbon value as a binder. However, the coal tar pitch with high coking residue value also has a higher softening point, which requires a higher mixing temperature, and the process parameters of forming and roasting should be adjusted accordingly. HP and UHP Graphite Electrode need to be dipped 1 to 2 times, and the joints need to be dipped 2 to 3 times. The performance of the impregnant has a great influence on the impregnation effect (infiltration and weight gain). With the advancement of science and technology, domestic carbon factories have accumulated certain experience in the production of UHP graphite electrodes, and the yield of UHP graphite electrodes that can reach the international advanced level has been greatly improved.
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