Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
  • C21C1/00—Refining of pig-iron; Cast iron
  • C21C1/02—Dephosphorising or desulfurising
  • C21C1/025—Agents used for dephosphorising or desulfurising
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
  • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
  • C21C7/04—Removing impurities by adding a treating agent
  • C21C7/064—Dephosphorising; Desulfurising
  • C21C7/0645—Agents used for dephosphorising or desulfurising
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/10—Reduction of greenhouse gas [GHG] emissions
  • Y02P10/134—Reduction of greenhouse gas [GHG] emissions by avoiding CO2, e.g. using hydrogen

Definitions

• the invention relates to an agent for the treatment of molten metals, in particular molten pig molten metals, to a process for the preparation of an agent for the treatment of molten metals, and to the use of a composition for the treatment of molten metals.
• the pig iron and foundry iron produced in blast furnaces, in cupolas or in other aggregates contains sulphurous and phosphorus contents due to operational and process conditions, which must be reduced before processing into steel or cast iron in order to be able to set the required contents in the end product. Frequently, S levels ⁇ 0.0020% (20 ppm) and P contents ⁇ 0.005% (50 ppm) are required.
• a desulfurizing agent is known, which is composed of a mixture of 40 to 90 wt .-% technical calcium carbide and calcium carbonate, and 2 to 20% by weight of carbon dispersed therein, wherein the finely divided calcium carbonate / carbon Mixture under the trade name Diamidkalk is known.
• these mixtures have the disadvantage that the slags produced by the desulphurisation treatment after the injection process involve considerable amounts of iron, which leads to considerable iron losses. In view of the risk of desulfurization, some overdosage must be made to compensate for this effect.
• the metallurgical efficiencies of these mixtures with diamide lime are limited to about 25%.
• particularly reactive metals such as calcium, magnesium, aluminum or rare earth metals and alloys of reactive metals and alkaline compounds such z.
• the funds should be easy to handle and have a good flow and pneumatic conveying behavior.
• the object is achieved by a means for the treatment of molten metals, in particular for the desulfurization of pig iron melts, at least containing calcium oxide, optionally at least one further element in elemental and / or bound state, selected from the group of alkali metals, alkaline earth metals or earth metals and bitumen in an amount of 1 to 30 wt .-% or a mineral and / or paraffinic oil, in an amount of 1 to 25 wt.%.
• a petroleum derivative in particular the addition of bitumen and / or of mineral and / or paraffinic oil to an element in elemental and / or bound state, selected from the group of alkali metals, alkaline earth metals or earth metals, preferably to calcium oxide, CaO, a very effective desulphurising agent.
• a petroleum derivative in particular the addition of bitumen and / or of mineral and / or paraffinic oil to an element in elemental and / or bound state, selected from the group of alkali metals, alkaline earth metals or earth metals, preferably to calcium oxide, CaO, a very effective desulphurising agent.
• the inventive agent for the treatment of molten metal in particular for the desulfurization of pig iron melts, is not carried by the natural buoyancy or the expanding carrier gas bubbles to the surface of the melt, where it burns unused, or in the slag evolved from the smelting unit or from the treatment.
• the agent according to the invention for the treatment of molten metals is preferably mixed with an element in elemental and / or bound state selected from the group of alkali metals, alkaline earth metals or earth metals, more preferably with calcium oxide, CaO and / or Ca (OH) 2 . and is to the respectively required grain size, in particular from ⁇ 0, 1 to 1 mm, milled.
• the hydrogen released from the petroleum derivatives, in particular from bitumen and mineral and / or paraffinic oil is present atomically or in statu nascendi for a certain time after pyrolysis. This hydrogen is more intense in its overall effect than gases, for example from the steam-reforming process.
• the released carbon from the pyrolysis of the hydrogen carrier is probably atomic.
• Paraffins and / or paraffin oils can be added to the compositions according to the invention during their preparation, in particular during the milling. They not only bring about an increase in the desired metallurgical effects, but are also distinguished as flow improvers for the composition according to the invention.
• the inventive agent for the treatment of molten metals in particular for the desulfurization of pig iron melts, at least calcium oxide, optionally at least one further element in elemental and / or bound state, selected from the group of alkali metals, alkaline earth metals or earth metals (first Component) and bitumen in an amount of 1 to 30 wt .-%.
• the agent contains at least one further element in elemental and / or bound state selected from the group calcium carbide, calcium cyanamide, calcium hydroxide, calcium carbonate, calcium sulfate, dolomite, barium oxide, barium sulfate and alkali carrier (second component).
• at least one further element in elemental and / or bound state selected from the group calcium carbide, calcium cyanamide, calcium hydroxide, calcium carbonate, calcium sulfate, dolomite, barium oxide, barium sulfate and alkali carrier (second component).
• alkali metal carbonates and alkali metal sulfates selected from sodium and potassium carbonate or sulfate may also be mentioned by way of example, as well as minerals of the Foid group, such as, for example, albite, nepheline syenite or sodalite.
• bitumen unlike other carbonaceous compounds, such as coal, carbon, graphite, urea or rubber, bitumen does not present any safety risks, and that a desulfurizing agent of the prior art readily mixes with bitumen or cakes, and these Mixture or the plate can finally be crushed to a blowable or vibratable grain.
• an improved desulphurising effect of an element in the elemental and / or bound state selected from the group of alkali metals, alkaline earth metals or earth metals, which optionally contains at least one further element in the elemental and / or bound state selected from the group Caiciumoxids, Calcium carbide, calcium cyanamide, calcium hydroxide, calcium carbonate, calcium sulfate, dolomite, barium oxide, barium sulfate and alkali carriers.
• calcium oxide has a very good desulfurizing effect for a short time only at the beginning of a blowing-in treatment, since a layer (for example as CaSiO 4 ) forms around the calcium oxide grain which inhibits the diffusion of sulfur to the calcium oxide.
• a hydrogen phase from the pyrolysis (decomposition) of the petroleum derivative is formed around the calcium oxide grain during the desulfurization with the agent according to the invention.
• the released hydrogen and carbon steadily reduce the calcium sulfide layer on the calcium oxide grain, so that exposed calcium oxide or calcium can strongly desulfurize.
• the bitumen disintegrates not only calcium from calcium oxide but also barium from barite and strontium from celestine at the temperatures of the molten pig iron.
• bitumen is understood to mean a heavy, dark-colored multi-substance mixture of organic substances consisting of high molecular weight, long-chain, aliphatic and aromatic hydrocarbon compounds, produced by vacuum distillation from crude oil.
• the properties of the different types of bitumen are determined by special test methods. These are defined in the DIN standards (Europanorm EN 12591) for road bitumen (softening point RuK (EP RuK), the breaking point after Fraigne, Nadelpenetration). By adding additional components, the physical properties can be changed in a targeted manner.
• Bitumen grades are preferably used for this metallurgical work, which contain a low sulfur content, in particular less than 1, 5 wt .-%.
• the invention also relates to a process for the preparation of an agent for the treatment of molten metals, in particular for the desulfurization of pig iron melts, which is characterized in that an element in elemental and / or bound state, selected from the group of alkali metals, alkaline earth metals or earth metals (First component) and optionally at least one further element in the elemental and / or bound state selected from the group of calcium oxide, calcium carbide, calcium cyanamide, calcium hydroxide, calcium carbonate, calcium sulfate, dolomite, barium oxide, barium sulfate and alkali carriers mixed with bitumen and then to the size of a shaking grain crushed or blowable grain are ground.
• an element in elemental and / or bound state selected from the group of alkali metals, alkaline earth metals or earth metals (First component) and optionally at least one further element in the elemental and / or bound state selected from the group of calcium oxide, calcium carbide, calcium cyanamide, calcium hydrox
• These temperatures are achieved by a common grinding by the grinding work. It has been shown that at these temperatures a particularly good adhesion between the individual components and bitumen arises.
• first, optionally already ground component, and optionally a further (first and / or second) component with liquefied bitumen using suitable stirrers (for example twin-shaft machines), in order finally to produce the following Discharge from the mixing machine and the cooling plates formed to break or grind.
• suitable stirrers for example twin-shaft machines
• the components will preferably be ⁇ 1.0 mm.
• a grain size of ⁇ 1, 0 mm in bitumen composite has good flow properties.
• a first blowable component for example, Caiciumoxid
• a further component or other slag components for example, a further component or other slag components
• blasstoryem granular bitumen in the lance.
• a first component such as Caiciumoxid or mixtures thereof comes from a, usually larger container (dispenser) and the blowable, fine-grained bitumen from a second blower.
• bitumen and optionally a further first or second component as a blowable grain
• an agent according to the invention containing calcium oxide and bitumen and optionally one further first or second component as a blowable grain, and on the other side an alkali carrier, such as, for example, albite or nepheline syenite.
• a particularly preferred embodiment of the agent for the treatment of molten metal in particular for the desulfurization of pig iron melts and for the reduction of ores, contains bitumen in an amount of 1 to 30 wt .-% and Caiciumoxid.
• the preparation of the agent according to the invention is advantageously carried out similarly to the production of asphalt, characterized in that a first component, for example, Caiciumoxid, optionally with the addition of a second component, for example, nepheline syenite, liquid bitumen is added and stirred. Subsequently, plates are poured and then crushed or ground.
• a first component for example, Caiciumoxid
• a second component for example, nepheline syenite
• bitumen Since only limited amounts of bitumen are added, it is also conceivable a first component, such as a metallurgically active component z.
• a first component such as a metallurgically active component z.
• Caiciumoxid to mix with a correspondingly fine-grained bitumen granules.
• the introduction into the molten metal can then be carried out by the mono process, i. it is only worked with a blower.
• the invention further relates to the use of an agent for treating molten metals, in particular pig iron melts, for desulfurization by blowing, stirring or adding a small-sized mold into a treatment vessel.
• an inventive composition comprising a first component, for example, Caiciumoxid, another component, in particular an alkali carrier with 10 - 15 wt .-%, for example, Na 2 0 and bitumen with 2 - 30 wt .-%.
• the invention further relates to the use of the agent according to the invention for the treatment of molten metals, in particular pig iron melts, for dephosphorization by blowing, stirring or adding a small-sized mold into a treatment vessel.
• the agent according to the invention for the treatment of molten metals contains at least calcium oxide, optionally at least one further element in elemental and / or bound state, selected from the group of alkali metals, alkaline earth metals or earth metals (first component) and a mineral and / or paraffinic oil, in an amount of 1 to 25 wt .-% (oil content).
• the agent contains at least one further element in the elemental and / or bound state selected from the group of calcium carbide, calcium cyanamide, calcium hydroxide, calcium carbonate, calcium sulfate, dolomite, barium oxide and barium sulfate.
• mineral oils are oils derived from petroleum or coal. These include in particular normal, light and extra light fuel oil, diesel fuel and kerosene. According to the invention, a high proportion of saturated alkanes is preferred since, in particular for the pig iron treatment, a high proportion of hydrogen is desired and an additional introduction of carbon into the melt is undesirable.
• Paraffinic oils are understood to mean pure saturated hydrocarbons having the general empirical formula C n H 2 n + 2. Since means for the treatment of molten metal usually discharged by way of a so-called mono-injection from a bucket and are blown with a transport gas through a refractory injection lance into the molten iron melt, the agent according to the invention must be vaporizable, lubricious and free-flowing. Therefore, it is essential that the agent is fine-grained and capable of blowing. This is accomplished by including at least a majority of the mineral and / or paraffinic oil from the ceria oxide in a capillary surface structure and optionally in the surface structure of another calcium or alkali containing component. Caicium oxide in particular serves as adsorbent for mineral and / or paraffinic oils (adsorbate).
• the optimum proportion of oil must be determined for each inventive agent for the treatment of molten metal. This is the skill of a professional. As a result, after the addition of oil, the agent according to the invention must be capable of blowing, free-flowing and lubricious, based on the selected type of oil and the state of the calcium oxide and the other components.
• the oil content to be used is therefore dependent on at least two parameters, namely the composition of the agent consisting of Caiciumoxid as Weichbranntkalk, Mittelbranntkalk or Hartbranntkalk, and optionally a further calcium or alkaline component and the nature and viscosity of the oil or the oil mixture.
• the particular adsorbent ie with calcium oxide and optionally a further component containing calcium, magnesium or alkali
• the saturation value ie the Langmuir adsorption isotherm, can be determined for a particular oil or oil mixture.
• a guideline for example Weichbranntkalk as adsorbent and heating oil HEL as adsorbate are 3.5 to 1 1, 5 wt .-%.
• calcium oxide has a short-term very good desulfurizing effect only at the beginning of a blow-in treatment, because granulated quicklime can sinter at the prevailing temperatures. This means that the active surface area decreases.
• An inventive agent does not show such sintering, whereby the long-lasting desulfurization as well as the lower or missing tendency to desulfurize the agent according to the invention can be explained.
• the preparation of a composition according to the invention is carried out, for example, by mixing or spraying CaO and optionally a further calcium and / or alkaline component with a mineral and / or paraffinic oil.
• the agent according to the invention is then further sieved in order to achieve a uniform grain size.
• Mineral oils with a kinematic viscosity of approximately 2.0 to 4.5 mm 2 / s proved to be particularly suitable.
• This addition is particularly preferred for soft lime, since the dust is significantly reduced and the absorption capacity of the lime is very pronounced.
• Spraying Weichbranntkalk with mineral and / or paraffinic oil immediately after firing also proves to be particularly advantageous since this prevents hydration of the CaO.
• CaO with this oil addition immediately after emptying it allows this lime for treatments in ladle metallurgy to use without risking an increase in water content. If necessary, the oil content is subsequently increased in a mixer.
• the invention further relates to the use of an agent for the treatment of metal melts, in particular pig iron melts, for desulfurization by blowing, stirring or adding a small-sized mold into a treatment vessel or transfer ladle.
• alpha-relationship provides an illustrative value by indicating the amount of treatment agent in kg per tonne of pig iron needed to reduce the sulfur content by 0.010% by weight.
• Example 2 - Bitumen In an experiment, 4.2 kg / t of calcium oxide containing 5.0 wt .-% bitumen by means of the carrier gas nitrogen were injected via a lance by mono-injection into an open pan with 170 t of pig iron. The agent containing ceria and bitumen was previously milled to the size of a blowable grain at a temperature of 60 ° C. The sulfur content (S (start)) determined before treatment was 0.040% by weight. After the treatment, a sulfur content (S (end)) of 0.0030% by weight was determined, resulting in an ⁇ value of 1.07.
• the performance of the composition according to the invention becomes clear.
• the ⁇ -value can be reduced by 60 to 85%, which is reflected directly in the spent desulfurization and thus in the costs.
• the agent according to the invention is suitable for the treatment of molten metals, in particular of pig iron melts, by the mono-, co- or multi-injection process, but after stirring, for example according to the KR stirring system.
• Example 5 - Bitumen
• bitumen About 5 wt .-% bitumen was added in the solid state to Caiciumoxid with 10 wt .-% albite. This mixture was ground to a blowable granulation. The desired S content was ⁇ 70 ppm in the conventional use of the lime-fluorspar mixture. With the addition of the bitumen, 20-30 ppm sulfur was obtained in the treated pig iron. In this series of experiments it was examined how far the injection quantity can be reduced in order nevertheless to reach the demanded 70 ppm. This is achieved by reducing the planned injection quantity by approx. 20%.
• a composite of nepheline syenite and bitumen and possibly with lime can break down via blowing, preferably with air effectively the phosphorus content in pig iron.
• Particularly effective is the use of water glass Na 2 O Si0 2 in the ratio 1: 1 in conjunction with bitumen and lime (CaO);
• This complex with 3 - 5 wt .-% bitumen results in pig iron but also in cast iron a quiet course of treatment.
• the decrease in the phosphorus content is 50 to 80% in the treatment in the transfer ladle; the specific consumption figures were between 5 and 10 kg / t, depending on the starting content and the desired final content.
• bitumen to inoculants for spheroidal cast iron or vermicular cast iron can reduce the decay effect of the inoculant.
• inoculants containing rare earths in addition to the usual components extends bitumen vaccine effect. Additions of 0.3 to 1 .0 wt .-% are sufficient, depending on the size of the casting.
• the seed effect can be further increased if the bitumen is added to a sulphate, carbonate and / or oxide of the seeded metals, such as barium, strontium, magnesium, calcium or aluminum, in particular barium sulfate (barium) calcium sulfate (gypsum), strontium sulfate (celestin).
• barium sulfate barium calcium sulfate (gypsum)
• strontium sulfate celestin
• 1, 0 to 1, 5 wt .-% which are preferably incorporated in the liquid bitumen.
• the metallurgical relationships for this reinforcement or extension of the vaccine effect are not known.
• the experiments have surprisingly shown that the metal compounds can be used solely for the seeding of cast iron when they are coated with bitumen (in the liquid state) or adhere to one another by mechanical treatment (grinding).
• the decisive factor is the preparation for the appropriate grain size, which can vary from 0.2 mm to 6 mm
• petroleum or petroleum processing derivatives may be used instead of bitumen.
• the choice of which oil or which C-H compound from the coke recovery or other welding processes is used must be determined individually.
• a mixture of calcium oxide and bitumen is very well suited for the desulphurisation of flue gases, such as from the coking of coal or sulfur-rich fuels, such as oil, in annealing furnaces.
• the bitumen immediately releases calcium at the appropriate temperature, which binds sulfur from the flue gas.
• the agent according to the invention can also be used for the desulfurization of flue gases according to the invention.
• the pre-treatment sulfur content S a was 0.042% by weight of the pre-treatment phosphorus content P a was 0.072% by weight.
• the injection rate was 49 kg / t.
• the performance of the composition according to the invention becomes clear.
• the a-value can be lowered by 76, 73, 71 or 68%, which is directly in the consumed desulfurizing agent and thus reflected in the cost.
• the composition according to the invention is suitable for the treatment of metal melts, in particular of pig iron melts, preferably according to the mono-process, but also for stirring in accordance with the KR stirring system.
• the agent according to the invention with a paraffinic oil content is suitable for the desulfurization and deoxidation and seeding of steel and cast iron.
• the disadvantageous threshold of the fine ore in direct reduction processes is suppressed or at least suppressed;
• the decay of the ore grains during reduction is avoided or reduced.
• the "baking" in the reduction region on the wall of the treatment chamber is avoided or suppressed. This can also be prevented by simultaneously introduced into the pan lime, or other combination of slag formers.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Treating Waste Gases (AREA)
• Manufacture Of Iron (AREA)

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• 2012
  • 2012-01-11 WO PCT/EP2012/050397 patent/WO2012095471A2/fr not_active Ceased
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  • 2012-01-11 CA CA2829030A patent/CA2829030C/fr active Active
  • 2012-01-11 US US13/978,963 patent/US9187792B2/en active Active
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