Steel quality role of secondary refining and continuous. Epa452f03034 air pollution control technology fact sheet epacica fact sheet flue gas desulfurization1 name of technology. Sulphur is a desirable element in steel when good machinability is required from the steel product. Desulphurization of steel at ladle furnace depends on temperature, amount of oxygen and sulphur in the steel, but mainly on chemical composition and physical.
To determine the influence, on the desulphurisation process, of the titanium oxide added in calcium aluminate slag, we experimented, in the. Desulphurization of stainless steel by using caoal2o3 based. Role of slag in the steel refining process in the ladle. The higher chromium, molybdenum and nitrogen contents result in a pitting resistance equivalent number pren of 40.
It follows from the results figures 1 and 2 that the main part of desulphurisation of steel took place during the treatment of steel in the ladle furnace, lf, and in the vacuum unit, vd. Recent progress in internal hot metal desulphurization by multiinjection at thyssenkrupp stahl ags tks steelworks. Nov 12, 2019 hot metal desulphurisation serves as the main unit process for removing sulphur in blast. At this stage the oxidizing slag is removed and then lime flux is added to form basic slag with high cao content. An example process flow diagram is shown with material and energy balance for plant capacity 1mmtpa. Kr hot metal desulfurization system steel plantech. Demand for high purity steel is becoming stronger as quality demands for steel become higher. Desulfurization refers to the industrial process of removing sulfur from a mineral resource mixture such as crude oil. Flue gas desulphurisation in industrial plants, power plants or waste incineration plants depends on nozzles that guarantee precise operation over a long period of time and withstand extremely aggressive environmental conditions. Dec, 2016 the desulphurisation rate of steel melts increases if the specific stirring energy is enhanced by increasing the gas flow rate or reducing the pressure on the bath surface.
Thermodynamic and kinetic aspects of the desulphurisation. That development was driven by the introduction of hot metal and steel desulphurization in integrated steelmaking plants. Yield improvements during iron desulfurization when. Desulfurization is the removal of sulfur or sulfur compounds as from coal or flue gas, mostly from fuels.
Desulphurization characteristics of ladle furnace slags of a low sulphur steel article pdf available in canadian metallurgical quarterly 464. Desulphurisation is a chemical process for the removal of sulfur from a material. Removal of sulphur from hot metal is called desulphurization of hot metal. Pdf desulphurization characteristics of ladle furnace slags. Sm is the last possibility to influence the steels chemistry. Thermodynamics of desulphurization of liquid steel there are four aspects which are important during the desulphurization of liquid steel. Flue gas desulphurisation plant purpose the flue gas desulphurisation fgd plant removes sulphur dioxide from the flue gas before it is released into the atmosphere and hence reduces our impact on the environment. Fluegas desulfurization fgd is a set of technologies used to remove sulfur dioxide so 2 from exhaust flue gases of fossilfuel power plants, and from the emissions of other sulfur oxide emitting processes such as waste incineration. Desulphurization of stainless steel by using caoal2o3. Desulphurization definition of desulphurization by the. In case of the steel slag the value of the sulphur partition coefficient usually rises with the increased activity of cao, which represents the exact. Sulphide capacity it is the ability of liquid slag to adsorb sulphur. A study of desulphurization process improvement in steel making. Thus, desulfurization sulfur removal from liquid steel is needed as a key process that is mainly achieved in ladles during secondary steelmaking.
A summary of corrosion tests in flue gas desulfurization. Desulphurization of steels is effective with rare earths at low oxygen contents. Desulphurisation and inclusion behaviour of stainless steel. The principles that must be met in order to obtain low sulphur content in steel can be summarized into the following. The work includes thermodynamic calculations of the slagmetal equilibrium, cfd modelling of slagmetal reactions, and plant trials. For the traditional fgd units the construction materials options were very little. It is known that impurities such as free sulphur, sulphur dioxide, marketers, finding materials etc. These are i sulphide capacity, ii sulphur distribution ratio, iii desulphurization potential, and iv rate of desulphurization. The desulphurisation effect was discussed based on the. Specific attention has been given to the desulphurisation behaviour and steel cleanliness. Sulphur removal in ironmaking and oxygen steelmaking frank nicolaas hermanus schrama. A caoal 2o 3caf 2based desulphuriser with high sulphide capacity was developed by laboratory experiments of steel desulphurisation and by considering the floatation of al 2o.
Desulphurization characteristics of ladle furnace slags of a low sulphur steel. Desulphurisation definition of desulphurisation by the free. One effective desulfurizer is a calciumsilicon alloy containing 30 percent calcium. To determine the influence, on the desulphurisation process, of the titanium oxide added in calcium aluminate slag, we experimented, in the laboratory phase, the steel treatment with a. This involves either the removal of sulfur from a molecule e. A robust, energy saving solution was sourced from unifrax. Flue gas desulfurization fgd wet, spray dry, and dry scrubbers type of technology.
Special alloys for flue gas desulfurization systems. Liquid steel at the end of the bof process has a high oxygen content. The sulphur removal rate in molten steel was found to be accelerated with increasing temperature and initial sulphur content in the steel. The deep desulphurisation behaviour and steel cleanliness of stainless steel refining in the low sulphur content period below 45 ppm %s by using the current limefluorspar based slag and an optimized limealumina slag have been studied and compared. Flue gas desulphurisation system manufacturer engineering.
For low sulphur steel grades desulfurization may be effectively conducted in the reducing slag stage of the steel making process in electricarc furnace. Scribd is the worlds largest social reading and publishing site. Materials to simulate the secondary stainless steel refining process, austenitic stainless steel ingots were collected after the aod process from a steel plant and used in the laboratory experiments. The paper focuses on an evaluation of the slag regime and steel desulphurisation in a ladle with the help of synthetic slags based on al2o3 containing various mass amounts of cr2o3 varying from 0.
Nov 11, 2017 desulfurization is the removal of sulfur or sulfur compounds as from coal or flue gas, mostly from fuels. The most commonly required desulfurization process is in natural gas, but it is also required for flue gas, coal and oil. Jul 30, 2016 thermodynamics of desulphurization of liquid steel there are four aspects which are important during the desulphurization of liquid steel. Desulphurization of steel and pig iron received prispjelo. However it is an unwanted element in most of the applications of steel due to the following reasons.
Control device absorption and reaction using an alkaline reagent to. Deep desulfurization by slags may be achieved in ladle. Desulfurization may be effectively conducted in the reducing slag stage of the steel making process in electricarc furnace. This paper examines the extent of sulphur removal from scrap metal charges when. Alloy 32750 is a super duplex stainless steel supplied in the hot worked and solution annealed condition. Combining force of manganese with oxygen and sulfur is higher than that of iron, so manganese can change feo and fes into mno and mns respectively and stay in the steel slag. To meet the restrictions on the environmental impact of sulphur oxide emissions, some coals need a degree of sulphur removal. By enhancing efficiency and limiting costs, sda lets you comfortably balance regulatory and financial ambitions. One of the main criteria was to maintain hot metal temperatures during the desulphurisation process. Available formats pdf please select a format to send.
For low sulphur steel grades steel desulphurisation is inevitable. Two steel structures were designed, incorporating moveable. The desulfurization reaction by powder blowing during the rh vacuum treatment is considered to be controlled by mass transfer of sulfur in molten steel to the surface of flux particle. Some of these corrosion test data have been reported previously. Dry flue gas desulphurisation lime spray drying fgd systems lsd is a dry scrubbing process that is generally used for lowsulfur coal. Flue gas desulphurisation economic solutions for the iron. Hot metal desulphurisation serves as the main unit process for removing sulphur in blast. The desulphurisation capability of optimized limealumina based slag was found to be similar. The desulphurisation rate of steel melts increases if the specific stirring energy is enhanced by increasing the gas flow rate or reducing the pressure on the bath surface. Removal of hydrogen sulphide h 2 s and carbon dioxide co 2 from natural gas is necessary to remove toxic gases, and conform to pipeline entry requirements. Sulfur is one of the most unwanted and detrimental impurities within the steel that undesirably affects the properties and the quality of the steel. This study introduces the desulphurisation process in rh vacuum recycling degassing degasser developed for the softkilled ultralowcarbon electrical steels. The fgd systems have been upgraded over the past 35 years from coated carbon steel to clad stainless steels and high nickel alloys.
Pdf desulphurization strategies in oxygen steelmaking. Desulphurisation and inclusion behaviour of stainless. Study of lf slag composition and its correlation with the. And when the content is low less than 1%, it can improve the strength of steel and has little influence on plasticity and toughness. Diesel hydro desulphurisation process flow diagram youtube. A twin ladle desulphurisation unit was designed by a leading engineering company based in eastern europe. Understanding the corrosive conditions of damped limestone fgd many analyses were done and several new corrosion resistant alloys were developed and used for the fgd systems. This process is used to upgrade the octane rating of.
This report aimed at determining the presence and removal of mercaptan sulphur in kerosene using colour indicator method. Pdf desulphurization of molten steel in rhdegasser by. Flue gas desulfurization fgd wet, spray dry, and dry scrubbers. Within several cooperative projects, kth royal institute of technology, ovako steel ab, and mefos have investigated the desulphurisation of bearing steel during vacuum degassing. Therefore, in this study, innovative approach in triz was applied to improve the desulphurization.
Refractories used in steel making or melting that are compatible with rare earths as deoxidizers are compounds such as magnesia. It does not include normal alloying prac tice in the furnace or at the ladle during tapping. Duplex and superduplex stainless steel grades for wet flue gas desulphurisation systems volume 105 issue 5 j. Pdf desulphurization characteristics of ladle furnace. Flue gas with high sulphur content from boiler is tapped off from the last heat trap after the economiser air preheaters by mixing the gas stream concurrently with lime slurry droplets for chemical treatment. Research on desulphurization of steel with calcium.
The removal process consumes large amounts of energy. As a super duplex stainless steel, it combines the desirable aspects of both austenitic and ferritic grades. Amine contactors and similar systems burn large amounts of fuel gas in order to heat the rich amine stream and regenerate the amine ready for reinjection. Yield improvements during iron desulfurization when utilizing flow aided compounds for modifying slag characteristics larry wolfe and lance olson, carmeuse lime 11 stanwix street, pittsburgh, pa 15222. Type 316l stainless steel is sometimes subject to localized corrosive attack in scrubber environments with certain combinations of ph and chloride content. Desulphurisation process in rh degasser for softkilled. When it comes to flue gas desulphurisation fgd, gea niros spray drying absorption sda process can give you an edge. This paper is a summary of 59 separate corrosion tests in nine fgd processes at 14 plant locations as shown in table i. The paper presents the results of laboratory experiments on steel desulphurisation with slag from the system caosio2tio2. 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. Sulphur removal in ironmaking and oxygen steelmaking. Desulphurization definition of desulphurization by the free. Metallic calcium desulfurizes by forming the very stable compound calcium sulfide cas, and it is alloyed with silicon because pure calcium reacts instantaneously with water and.
It predominantly involves a gaspurification industrial procedure used to remove hydrogen sulfide h 2 s and carbon dioxide co 2 from a given mineral resource. Research on desulphurization of steel with calcium aluminate. The process of removing impurities from steel is the most. Desulfurization of steel free download as powerpoint presentation. During the treatment of steel in the ladle furnace, lf. In this thesis work, some basic concepts about desulphurization of hot metal have been done based on a. A cohort of drivers including favourable government regulations supporting the production process of calcium formate to achieve gas desulphurization and its niche applications in tile adhesives and textiles industry have been determining the growth of the calcium formate market.
Hydrodesulfurization hds is a catalytic chemical process by which sulfur s is removed from natural gas and from refined petroleum products like petrol, jet fuel, kerosene, diesel fuel and fuel oils in the form of hydrogen sulfide or sulfur dioxide. Desulphurisation process in rh degasser for softkilled ultra. Stainless steel 316 was often the common and alone corrosion resistant alloy for consideration. George of tg associates on the flowability of powder materials. This is especially true for sulfur content, and there is now a need to make strict adjustments to the amount contained in the manufactured steel. Mar 27, 2018 sulfur content in diesel fuel is reduced by hydrodesulfurization process.
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