They feature a vacuum chamber equipped with two snorkels that is mounted to the ladle. Therefore, samples were taken before and after vacuum treatments in a steelmaking plant. Processtime optimization of vacuum degassing using a genetic. The liquid steel ladle is placed in a vacuum tank, which is connected to a vacuum pump system.
Au653294b2 process for vacuum degassing molten steel. Linzaustria, october 2006 secondary steelmaking session paper no. In large integrated steelmaking facilities, typically equipped with basic. Stage 1 and 2 with roots pumps, stage 3 with screw pump your advantages total process repeatability consistent degassing thanks to a dynamic vacuum module mastering any process condition.
Rh processes in large integrated steelmaking facilities, typically equipped with basic oxygen converters, secondary metallurgical processing is carried out mainly in ruhrstahl heraeus rh systems. Alternatively, in some processes, a reactive gas may be introduced. The vacuum degassing has been studied earlier by combining computational fluid dynamics cfd and thermodynamics 1517. Burgmann steelmakers who want to go for quality improvement by vacuum treatment in secondary metallurgy often have only a rough idea regarding the kind of vacuum pump to be selected, the needed suction capacity, the pump down time and the essential selection criteria. In steelmaking, impurities such as nitrogen, silicon, phosphorus, sulfur and excess carbon most important impurity are removed from the sourced iron, and alloying elements such as manganese, nickel, chromium, carbon and vanadium are added to produce different grades of steel. Applied vacuum engineering manufacture and supply a large range of professional quality vacuum chambers, vacuum pumps, complete degassing kits and accessories for businesses, individuals, schools and universities around the world. Utmost efficiency vd process the vacuum system must handle the complete gasflow and the significant amount of dust, created by metal. Edwards leads the way in vacuum for secondary metallurgy by a considerable. Fidol f filer8591 nma r united states patent process and apparatus for vacuum degassing 0f metal adolf sickbert, wattenscheideppendorf, germany, assignor to heppenstall company, pittsburgh, pa. Reducing hydrogen content to avoid embrittlement of steel. Investigation of slagrefractory interactions for the ruhrstahl heraeus rh vacuum degassing process in steelmaking. Our vacuum systems for mechanical steel degassing have been successfully applied to many secondary metallurgy processes at customers production facilities around the world. Introduction of japans first ld converter steelmaking process yawata, former yawata steel. If there is a rapid rise in the level of the degassing material close the vacuum isolation valve and allow a little air back into the chamber with the vent valve.
Rh rurhstahl heraeus versus vtd vacuum tank degasser. Abstractvacuum degassing processes are now an integral part of secondary steelmaking operations and besides the more obvious benefits of steel chemistry control to precise specifications, they also reduce the number of nonmetallic inclusions. Refining practice and application of the ladle furnace lf process. The ladle is equipped with porous plugs through which inert gas is injected into the melt in order to promote stirring. Author links open overlay panel munkyu cho a mariealine van ende b taehee eun a inho.
Vacuum degassing is a procedure that is used to improve the internal cleanliness of steel after the initial melt has occurred. Degassing technical vacuum degassing chambers and vacuum. During the vd process, the metallurgical work takes place in the steel ladle. Seamless pipe, flanges and castings can all suffer from hic if the manufacturing activities leave them in a susceptible state. That will collapse the degassing material and will break a lot of the surface air bubbles. Vacuum degassing, like other industrial processes, may be improved by computer modeling.
Vacuum degassing vacuum chambers laco technologies. The basic bessemer process is used a great deal on the continent for making, from a very suitable pig iron, a cheap class of steel, e. Oxygen steelmaking bos vessel or electric arc furnace eaf to the casting bay where the steel was cast into ingots. As the market leader with the largest installed base of dry pumps in the global steel industry, our understanding of steel degassing processes is unrivalled. During the primary steelmaking process, gases like oxygen o2, hydrogen h2 and nitrogen n2 dissolve in the liquid steel. Us3211545a process and apparatus for vacuum degassing of.
The analysis of the steel deoxidation process in a vacuum installation. Vacuum tank degassing is one of the oldest degassing techniques in use in the steel industry for improving steel quality. Au653294b2 au4478993a au4478993a au653294b2 au 653294 b2 au653294 b2 au 653294b2 au 4478993 a au4478993 a au 4478993a au 4478993 a au4478993 a au 4478993a au 653294 b2 au653294 b2 au 653294b2 authority au australia prior art keywords molten steel vacuum oxygen gas injecting treatment prior art date 19920826 legal status. Secondary refining for purposes of this article, secondary refining or secondary metallurgy is defined as any post steelmaking process performed at a separate station prior to casting and hot metal desulfurizaion. Deaeration of pastes and moist materials food production. Its advanced vacuum technology is suitable for rh plants, which demand higher suction capacity at low pressure xlpro vacuum installed on site. Steelmaking is the removal of excessive carbon, sulfur, phosphorus and other impurities from raw materials molten iron and the addition of appropriate alloy components. In the 1950s the first attempts were made to remove hydrogen by vacuum degassing. The principle of the process is to reduce the atmospheric pressure above the liquid steel in the vacuum remelt furnace. The vacuum degassing process is intended to reduce the amount of dissolved gases i. Vacuum degassing plays a critical role in the manufacture of steel. Mechanical vacuum systems for secondary metallurgy steel. The vacuum chamber is equipped with a hopper so as to make additions of.
A teeming ladle is placed in a vacuum tank, which is connected to a vacuum pump system. The vacuum degassing process allows the production of high quality, low carbon, and ultralow carbon steels and stainless steels, with minimal oxygen, hydrogen, and nitrogen contamination. The first two ways have not a practical importance for steelmaking, instead the third. Vacuum degassing processes for liquid steel ispatguru. Vacuum degassing yields stronger steelprocessors are. Secondary steelmaking is the processing of liquid steel after it has left the basic oxygen furnace bof or the electric arc furnace eaf and before the steel is poured into ingots or processed through a continuous caster. Recent advances and future prospects of refining technology. Vacuum metallurgy is that field of materials technology that deals with making, shaping, or treating metals in a controlled atmosphere, at pressures significantly less than normal atmospheric pressure. The hydrogen content after this degassing cycle is measured and if the metals hydrogen content is higher than the. Reductionelimination of dissolved gases, especially hydrogen and nitrogen. Vacuum degassing for steel making processthe degassing is the finest option for removing the gases and the air with the help o liquefied material.
With decades of experience providing vacuum solutions for vacuum degassing vd, vacuum oxygen decarburising vod and ruhrstahl heraeus rh processes, we can help you to improve productivity and reduce your operational. One of the most important goals of vacuum degassing is to reduce nitrogen content in the metal bath 2. After the vacuum degassing process is complete, the gas is removed from the vessel, and the pressure is returned to normal. The air pressure over the molten steel is reduced to approximately 1mm of. Vacuum degassing process for seamless pipes, forgings and. Quick pump down and pressure control in vacuum steel. Deoxidation is the metallurgical process for removing oxygen from molten steel. However, no attempt was made to optimize the vacuum. First of all, why choose vacuum pump for iron steel degassing. Process and apparatus for vacuum degassing 0f metal filed april 17, 1963 i 2 sheetssheet 2 jn venzor. Steelmaking is the process of producing steel from iron ore andor scrap. The purpose of vacuum metallurgy is to prevent contamination of metal by gases in the atmosphere. This process covers all functions in reduction period. With the proven modular system design we enable degassing and decarburising melt sizes up to 200 tonnes in electric steelmaking facilities.
By reducing the system pressure, the melt rises into the vacuum vessel where decarburization, degassing, and other degassing reactions take place. Quick pump down and pressure control in vacuum steel degassing w. Here you can get the latest information of the vacuum degassing process. Improving low carbon steel production in specialty steel. Argon gas is blown from the sides of one of the snorkels, circulating the molten steel into the vacuum chamber using the buoyancy of the blown gas and removing. Specific reactions are achieved with the inert gas by using basic slags flushing with inter gas causes turbulence and thus larger reaction surfaces between the slag, metal and vacuum atmosphere. In these studies the process was analyzed and a detailed understanding was gained, e. Investigation of slagrefractory interactions for the. In the present study, a dynamic model for the vtd has been developed. A vacuum degassing system or degasser is used in the secondary refining of steel subjecting molten metal to a vacuum to remove oxygen, hydrogen and nitrogen to produce ultralow carbon steel for the automotive, electrical, construction, and rail markets.
Vacuum degassing is normally performed in the ladle and the removal of dissolved gases. These include the temperature of the system, pressure in the vacuum chamber and chemical composition of the bath. Vacuum degassing process has been studied in the recent years by some. This paper demonstrates the use of a new model consisting of a genetic algorithm in combination with thermodynamic calculations and analytical process models to minimize the processing time during a vacuum degassing treatment of liquid steel. For example, bethlehem steel is using fluid dynamics analysis package f idap software developed by fluent in c. Rh degassers rh are suitable for quickly degassing from large quantities of molten steel.
Vacuum degassing of liquid steel is one of many secondarysteelmaking practices that can be used by todays steelmakers. This process was originally used for hydrogen removal from the liquid steel but presently it is also being used for secondary refining and has become increasingly important process of secondary steel making. Vacuum degassing is an important secondary steel making process. Steelmaking process an overview sciencedirect topics. Reduction of dissolved carbon for more ductile steel. Slags, vacuum degassing, steelmaking, steel cleanliness, inclusion removal. Vacuum for degassing busch vacuum solutions united states. These processes operate at varying vacuum levels, with different process gas loads, and in differing types of vacuum vessels, including tank, lid. Repeat that process so that you progressively pump the chamber down. Vacuum degassing of steel takes place after the molten steel has left the furnace and before the steel is poured into ingots or processed through a caster. Only crude composition and temperature control were possible by this route. Vacuum tank degassing vtd is widely used as a secondary steelmaking process to achieve very low concentrations of nitrogen, hydrogen, carbon, sulphur, and other elements in steel. If not removed before the material cures, gas bubbles will cause defects such as nodules, cavities, or hollows in. Vacuum degassing to remove carbon not only reduces imperfections, but also makes metals more ductile, or easily.
In order to clarify the effect of some parameters of the vacuum degassing process on the inclusion removal, an approach was taken whereby population and chemical composition of inclusions were related to the effective. Rh vacuum degassing processes and the hot metal desulphuriz. Aker solutions offers a complete range of services necessary to realize global projects including the provision of process technology integration, design, engineering, projectprogram management, procurement and construction. Care has to be taken, however, that the change in steel composition through loss of c, o, mn, etc. D of ladles with inert gas as the flushing and stirring medium is an easily handled process that asks for low investment cost. Vacuum degassing removes trapped gases from compounds such as resins or epoxies which become entrapped in the mixture when mixing the components. These facilities process steels in ladle sizes of over. Secondary refining american iron and steel institute. However through continued eaf process development, improved. The vacuum degassing process is applied during the steelmaking, not the finished item manufacturing process. Examples for the use of busch vacuum technology in degassing. The rh ruhrstahl heraeus process is carried out in a refractorylined vessel, equipped with two snorkels which are immersed in the steel bath. Vaccume degassing steelmaking industrial processes. About 95% of energy for an integrated steelmaking plant comes from solid fuel mainly coal, 34% from gaseous fuel and 12% from liquid fuel.
The acid bessemer suffered a decline in favour of the acid open hearth steel process, mainly due to economic factors which in turn has been ousted by the basic electric arc furnace coupled with vacuum degassing. Effective viscosity of slag and kinetic stirring parameter. These gases have a harmful effect on the mechanical and physical properties of steel. Generally speaking, energy constitutes a significant portion of production cost, from 20% to 40%, according to the estimation from world steel association 7. Assessment of inclusion analysis via manual and automated. Processtime optimization of vacuum degassing using a. Depending on the technical requirements of your degassing process, r 5 rotary vane vacuum pumps, mink claw vacuum pumps or cobra screw vacuum pumps are the most suitable models.
546 1442 140 729 55 1037 72 886 869 106 220 331 1117 395 405 429 1084 471 244 790 186 1034 538 1141 571 33 1459 780 765 695 660 470 267 31 1467 829 932 937 192 331 505 350 1106 1119