CA2398344C - Method for treating slags or slag mixtures on an iron bath - Google Patents
Method for treating slags or slag mixtures on an iron bath Download PDFInfo
- Publication number
- CA2398344C CA2398344C CA 2398344 CA2398344A CA2398344C CA 2398344 C CA2398344 C CA 2398344C CA 2398344 CA2398344 CA 2398344 CA 2398344 A CA2398344 A CA 2398344A CA 2398344 C CA2398344 C CA 2398344C
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- slags
- bath
- weight
- steel
- carbon
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- 239000002893 slag Substances 0.000 title claims abstract description 84
- 238000000034 method Methods 0.000 title claims abstract description 46
- 239000000203 mixture Substances 0.000 title claims abstract description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims description 24
- 229910052742 iron Inorganic materials 0.000 title claims description 12
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 65
- 239000010959 steel Substances 0.000 claims abstract description 65
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims abstract description 37
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 37
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 31
- 239000000969 carrier Substances 0.000 claims abstract description 13
- 229910052751 metal Inorganic materials 0.000 claims abstract description 13
- 239000002184 metal Substances 0.000 claims abstract description 13
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 24
- 239000000126 substance Substances 0.000 claims description 19
- 229910000805 Pig iron Inorganic materials 0.000 claims description 16
- 229910052681 coesite Inorganic materials 0.000 claims description 15
- 229910052906 cristobalite Inorganic materials 0.000 claims description 15
- 229910052682 stishovite Inorganic materials 0.000 claims description 15
- 229910052905 tridymite Inorganic materials 0.000 claims description 15
- 239000007788 liquid Substances 0.000 claims description 11
- 238000007670 refining Methods 0.000 claims description 10
- 239000006004 Quartz sand Substances 0.000 claims description 5
- 239000000654 additive Substances 0.000 claims description 5
- 229910001570 bauxite Inorganic materials 0.000 claims description 5
- 238000001816 cooling Methods 0.000 claims description 4
- 230000002378 acidificating effect Effects 0.000 claims description 3
- 230000000996 additive effect Effects 0.000 claims description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 3
- 229910052760 oxygen Inorganic materials 0.000 claims description 3
- 239000001301 oxygen Substances 0.000 claims description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims 4
- 229910052593 corundum Inorganic materials 0.000 claims 4
- 239000000377 silicon dioxide Substances 0.000 claims 4
- 235000012239 silicon dioxide Nutrition 0.000 claims 4
- 229910001845 yogo sapphire Inorganic materials 0.000 claims 4
- 238000006722 reduction reaction Methods 0.000 description 13
- 235000013980 iron oxide Nutrition 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 5
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- 238000007664 blowing Methods 0.000 description 2
- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- 230000004907 flux Effects 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 229920001296 polysiloxane Polymers 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000005187 foaming Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B5/00—Treatment of metallurgical slag ; Artificial stone from molten metallurgical slag
- C04B5/06—Ingredients, other than water, added to the molten slag or to the granulating medium or before remelting; Treatment with gases or gas generating compounds, e.g. to obtain porous slag
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B3/00—General features in the manufacture of pig-iron
- C21B3/04—Recovery of by-products, e.g. slag
- C21B3/06—Treatment of liquid slag
-
- 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
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/36—Processes yielding slags of special composition
-
- 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
- C21C7/0025—Adding carbon material
-
- 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
- C21C7/0087—Treatment of slags covering the steel bath, e.g. for separating slag from the molten metal
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/04—Working-up slag
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B2400/00—Treatment of slags originating from iron or steel processes
- C21B2400/02—Physical or chemical treatment of slags
- C21B2400/022—Methods of cooling or quenching molten slag
- C21B2400/028—Methods of cooling or quenching molten slag with the permanent addition of cooled slag or other solids
-
- 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
- Y02P10/20—Recycling
-
- 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
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
Abstract
In a method for treating slags or slag mixtures having iron oxide contents of > 5 wt.%, in particular steelworks slags, in which the steel slags optionally mixed with other slags are charged onto a metal bath, a steel bath having a carbon content of < 1.5 wt.%, preferably < 0.5 wt.%, is used as the metal bath and the steel bath, after the charging of the steel slags, is carburized to above 2.0 wt.% C, preferably > 2.5 wt.% C, by introducing carbon or carbon carriers.
Description
i METHOD FOR TREATING SLAGS OR SLAG MIXTURES ON AN IRON BATH
The invention relates to a method for treating slags or slag mixtures having iron oxide contents of >5 wt.%, in particular steelworks slags, in which the steel slags optionally mixed with other slags are charged onto a metal bath.
From EP 666 930 Bi, a method for producing steel and hydraulically active binders has already been known, by which steel slags are reduced using pig iron and, in particular, the carbon content present in the pig iron, thus causing the refining of the pig iron bath and the reduction of the carbon content of the bath to, for instance, below half of the carbon content present in the pig iron, on the one hand while, -at the same time, causing the iron oxide from the steel slag to be reduced to iron and get into the metal bath. The known method was optimized substantially with a view to enabling the at least partial reduction of large quantities of steel slags using slight amounts of molten pig iron. A substantial curtailment of the method by using larger quantities of molten pig iron is not readily feasible with that known method, wherein, for one part, molten pig iron is usually present at comparatively low temperatures thus eventually rendering problematic. the rheological properties of slags and, for the other part, when charging liquid steel slags onto large quantities of molten pig iron, extremely vigorous reactions will be observed, which, in the event of unfavourable rheological properties of the slags, may provoke the formation of undesired foamed slags or the occurrence of slag spittings.
The formation of such foamed slags, as a result, will cause a retardation of the reaction such that relatively long treatment times will become necessary.
The invention aims to further develop a method of the initially defined kind to the extent that with a relatively short reaction time the method heat formed in the course of the method can be optimally utilized and a highly fluid steel slag can be maintained during the reduction, which will persistently impede the formation of foamed slags and, at the same time, prevent local overreactions involving undesired liquid slag spittings.
To solve this object, the method according to the invention essentially consists in that a steel bath having a carbon content of <1.5 wt.%, preferably <0.5 wt.$ , is used as said metal bath and that the steel bath, after the charging of the steel slags, is carburized to above 2.0 wt.% C, preferably >2.5 wt.% C, by introducing carbon or-carbon carriers. By providing a metal bath having a comparatively low carbon content, i.e. a steel bath, at the onset of the slag reduction, local overreactions and vigorous reactions causing large amounts of gas to be formed will be prevented such that the formation of foamed slag will no longer be observed. In order to conduct such a method in an economical and largely autothermical manner, it is particularly advantageous if the method heat forming in the method is used immediately.
Therefore, the method according to the invention advantageously is carried out in a manner that a pig iron bath isprovided and refined with oxygen to a carbon content of <0.5 wt.% , whereby a bath temperature of above 1570 C, in particular about 1620 C, is adjusted, that liquid steel slag is charged onto the refined steel bath and carbon is introduced into the bath after a temperature equalization, wherein SiOZ-containing corrective substances such as, e.g., blast furnace slag, quartz sand and/or A1203-containing corrective substances such as, e.g., bauxite are added in order to lower the basicity to <1.5 and to adjust an A1203 content of >10 wt.% , respectively. By ensuring the formation of a steel bath onto which the steel slags are subsequently charged,- immediately as a prestage within the same method by means of a refining procedure, the method heat forming during refining, by which the original pig iron bath is substantially heated, can be directly utilized for a temperature equalization with the steel slag to be applied, wherein it is feasible, due to the high temperature, to immediately melt down, and introduce into the slag, also corrective substances and, in particular, Si02-containing corrective substances as are required for the adjustment of the desired basicity. Onto the steel bath which is appropriately heated to temperatures of above 1570 C by the refining procedure is, thus, immediately added either at least a portion of the Si02-containing corrective substances required for basicity adjustment so as to cause these corrective substances to be heated and at least partially melted, or the steel slag, wherein it is feasible to add the Si02-containing corrective substances together with the liquid steel slag. Due to the addition of such Si02-containing corrective substances and, in particular, the opportunity to simultaneously charge additives such as, for instance, cooling scrap or fine ore, the high latent heat of the refined steel bath is directly used in the process and it is feasible, by the addition of iron oxide carriers, to effect an efficient temperature control by which iron oxides are largely reduced at the same time and a high amount of molten iron is, thus, formed of such iron oxide carriers which are usually difficult to process, such as, for instance, fine ores.
Following steel slag charging, the carbon content of the steel bath is then continuously raised and the desired reduction work is performed while blowing carbon carriers into the steel bath. The carbon monoxide formed may subsequently be afterburned such that the method, in the main, can be operated in a largely autothermical manner and the introduction of additional energy can be obviated. Advantageously, the method according to the invention in that case is carried out in a manner that the basicity is adjusted to 1.1. to 1.4 and the carbon content of the bath is adjusted to >2.5 wt.% .
The method according to the invention advantageously is carried out in a manner that the steel slag is added to the steel bath at a weight quantity ratio of 1:3 to 1:6, preferably about 1:4, whereby the melting heat required for fluxes will be immediately available due to the relatively large quantity of metal bath charged and exhibiting a high temperature level after the refining procedure. In particular, it is feasible in an advantageous manner to add quartz sand in amounts ranging from 150 to 250 kg/ton steel slag, and bauxite in amounts ranging from 200 to 300 kg/ton steel slag, whereby the selected way of addition causes the fluxes to be sufficiently homogenized and hence completely melted and reacted in the slag so as to directly yield a cement-technologically usable product.
In a particularly advantageous manner, the liquid slag mixtures are supplemented with fine ores or iron oxide carriers in order to adjust an iron oxide content of above 8 wt.% , whereby it is feasible, simultaneously with the desired reduction of the steel slag, to reduce even hardly processible ores by the same method and use this admixture for controlling the desired reaction temperatures. For the same purpose, additives such as, e.g., cooling scrap or fine ores may advantageously be melted down in the metal bath during or after refining.
In a particularly advantageous manner, acidic-gangue iron oxide carriers may be added, thus enabling the appropriate lowering of the basicity to cement-technologically desirable target basicities simultaneously with the reduction of metallic iron from such iron oxide carriers. In doing so, it is advantageously proceeded such that the addition of iron oxide carriers such as, e.g., acidic gangue weak ores or fine ores, after the addition of the molten slags or slag mixtures onto the steel bath, at least partially is effected at the same time as the carburization of the steel bath, corrective substances containing CaO, A1203 and/or Si02, in general, being advantageously added to the molten slags or slag mixtures.
The invention relates to a method for treating slags or slag mixtures having iron oxide contents of >5 wt.%, in particular steelworks slags, in which the steel slags optionally mixed with other slags are charged onto a metal bath.
From EP 666 930 Bi, a method for producing steel and hydraulically active binders has already been known, by which steel slags are reduced using pig iron and, in particular, the carbon content present in the pig iron, thus causing the refining of the pig iron bath and the reduction of the carbon content of the bath to, for instance, below half of the carbon content present in the pig iron, on the one hand while, -at the same time, causing the iron oxide from the steel slag to be reduced to iron and get into the metal bath. The known method was optimized substantially with a view to enabling the at least partial reduction of large quantities of steel slags using slight amounts of molten pig iron. A substantial curtailment of the method by using larger quantities of molten pig iron is not readily feasible with that known method, wherein, for one part, molten pig iron is usually present at comparatively low temperatures thus eventually rendering problematic. the rheological properties of slags and, for the other part, when charging liquid steel slags onto large quantities of molten pig iron, extremely vigorous reactions will be observed, which, in the event of unfavourable rheological properties of the slags, may provoke the formation of undesired foamed slags or the occurrence of slag spittings.
The formation of such foamed slags, as a result, will cause a retardation of the reaction such that relatively long treatment times will become necessary.
The invention aims to further develop a method of the initially defined kind to the extent that with a relatively short reaction time the method heat formed in the course of the method can be optimally utilized and a highly fluid steel slag can be maintained during the reduction, which will persistently impede the formation of foamed slags and, at the same time, prevent local overreactions involving undesired liquid slag spittings.
To solve this object, the method according to the invention essentially consists in that a steel bath having a carbon content of <1.5 wt.%, preferably <0.5 wt.$ , is used as said metal bath and that the steel bath, after the charging of the steel slags, is carburized to above 2.0 wt.% C, preferably >2.5 wt.% C, by introducing carbon or-carbon carriers. By providing a metal bath having a comparatively low carbon content, i.e. a steel bath, at the onset of the slag reduction, local overreactions and vigorous reactions causing large amounts of gas to be formed will be prevented such that the formation of foamed slag will no longer be observed. In order to conduct such a method in an economical and largely autothermical manner, it is particularly advantageous if the method heat forming in the method is used immediately.
Therefore, the method according to the invention advantageously is carried out in a manner that a pig iron bath isprovided and refined with oxygen to a carbon content of <0.5 wt.% , whereby a bath temperature of above 1570 C, in particular about 1620 C, is adjusted, that liquid steel slag is charged onto the refined steel bath and carbon is introduced into the bath after a temperature equalization, wherein SiOZ-containing corrective substances such as, e.g., blast furnace slag, quartz sand and/or A1203-containing corrective substances such as, e.g., bauxite are added in order to lower the basicity to <1.5 and to adjust an A1203 content of >10 wt.% , respectively. By ensuring the formation of a steel bath onto which the steel slags are subsequently charged,- immediately as a prestage within the same method by means of a refining procedure, the method heat forming during refining, by which the original pig iron bath is substantially heated, can be directly utilized for a temperature equalization with the steel slag to be applied, wherein it is feasible, due to the high temperature, to immediately melt down, and introduce into the slag, also corrective substances and, in particular, Si02-containing corrective substances as are required for the adjustment of the desired basicity. Onto the steel bath which is appropriately heated to temperatures of above 1570 C by the refining procedure is, thus, immediately added either at least a portion of the Si02-containing corrective substances required for basicity adjustment so as to cause these corrective substances to be heated and at least partially melted, or the steel slag, wherein it is feasible to add the Si02-containing corrective substances together with the liquid steel slag. Due to the addition of such Si02-containing corrective substances and, in particular, the opportunity to simultaneously charge additives such as, for instance, cooling scrap or fine ore, the high latent heat of the refined steel bath is directly used in the process and it is feasible, by the addition of iron oxide carriers, to effect an efficient temperature control by which iron oxides are largely reduced at the same time and a high amount of molten iron is, thus, formed of such iron oxide carriers which are usually difficult to process, such as, for instance, fine ores.
Following steel slag charging, the carbon content of the steel bath is then continuously raised and the desired reduction work is performed while blowing carbon carriers into the steel bath. The carbon monoxide formed may subsequently be afterburned such that the method, in the main, can be operated in a largely autothermical manner and the introduction of additional energy can be obviated. Advantageously, the method according to the invention in that case is carried out in a manner that the basicity is adjusted to 1.1. to 1.4 and the carbon content of the bath is adjusted to >2.5 wt.% .
The method according to the invention advantageously is carried out in a manner that the steel slag is added to the steel bath at a weight quantity ratio of 1:3 to 1:6, preferably about 1:4, whereby the melting heat required for fluxes will be immediately available due to the relatively large quantity of metal bath charged and exhibiting a high temperature level after the refining procedure. In particular, it is feasible in an advantageous manner to add quartz sand in amounts ranging from 150 to 250 kg/ton steel slag, and bauxite in amounts ranging from 200 to 300 kg/ton steel slag, whereby the selected way of addition causes the fluxes to be sufficiently homogenized and hence completely melted and reacted in the slag so as to directly yield a cement-technologically usable product.
In a particularly advantageous manner, the liquid slag mixtures are supplemented with fine ores or iron oxide carriers in order to adjust an iron oxide content of above 8 wt.% , whereby it is feasible, simultaneously with the desired reduction of the steel slag, to reduce even hardly processible ores by the same method and use this admixture for controlling the desired reaction temperatures. For the same purpose, additives such as, e.g., cooling scrap or fine ores may advantageously be melted down in the metal bath during or after refining.
In a particularly advantageous manner, acidic-gangue iron oxide carriers may be added, thus enabling the appropriate lowering of the basicity to cement-technologically desirable target basicities simultaneously with the reduction of metallic iron from such iron oxide carriers. In doing so, it is advantageously proceeded such that the addition of iron oxide carriers such as, e.g., acidic gangue weak ores or fine ores, after the addition of the molten slags or slag mixtures onto the steel bath, at least partially is effected at the same time as the carburization of the steel bath, corrective substances containing CaO, A1203 and/or Si02, in general, being advantageously added to the molten slags or slag mixtures.
In the main, the refining procedure carried out in the first stage yields a particularly favourable energy balance with the high energy amounts released during the refining of the pig iron bath being directly usable within the process.
Any desired slags rich in Si02 are basically suitable for the adjustment of the desired target basicity and Si02-containing corrective substances may optionally be charged.
In the following, the invention will be explained in more detail by way of an exemplary embodiment.
In a converter, 8 tons of molten pig iron were converted into a steel bath by the introduction of 280 Nm3 oxygen through bottom tuyeres. The directional analysis of the molten pig iron showed a carbon content of 3.9 wt.% , a silicone content of about 0.3 wt.% and residual iron. After refining, during which, departing from a bath temperature of 1470 C, a final temperature of 1620 C was reached due to the exothermic reaction occurring, the liquid steel bath had a carbon content of 0.3 wt.% =, a silicone content of 0.003-% and residual iron.
After this, 2 tons of liquid steel slag were charged onto that liquid steel bath. The steel slag was characterized by the following analysis:
Steel slag wt.%
CaO 48.6 Si02 19.1 A1203 2.2 M O 3.2 Ti02 1.5 FeO 22.7 MnO 2.7 CaO/Si02 2.5 Due to the relatively low bath carbon content of the steel bath present, the reduction reaction of the metal oxides contained in the steel slag involves substantially fewer mass conversions immediately upon the addition of the liquid steel slag. If pig iron were directly charged in the respective quantitative ratios, high amounts of CO would be released quickly, which might lead to intensive slag foaming or slag spitting.
After the charging of the steel slag onto the steel bath, temperature equalization between slag and metal bath is effected so as to enable possibly solid slag portions to be completely reconverted into the liquid state. Temperature equalization results in temperatures of about 1500 C.
After temperature equalization had been completed, 580 kg coal were blown into the steel bath at a blowing rate of 25 kg/min;
additionally introduced were 370 kg quartz sand at a rate of 24 kg/min and 535 kg bauxite at a rate of 28 kg/min.
A metal bath containing 4.5 wt.% dissolved carbon at a temperature of about 1490 C remained at the end of the desired reduction reaction. Depending on the corrective substances selected and the composition of the steel slag, the pig iron thus formed back naturally also may contain respective other metals than iron.
By means of the corrective substances, the desired target basicity as appears desirable for the cement-technological further use of the treated slag was adjusted, on the one hand, while, at the same time effecting a reduction of the metal oxides to the following directional analysis of the treated steel slag.
Any desired slags rich in Si02 are basically suitable for the adjustment of the desired target basicity and Si02-containing corrective substances may optionally be charged.
In the following, the invention will be explained in more detail by way of an exemplary embodiment.
In a converter, 8 tons of molten pig iron were converted into a steel bath by the introduction of 280 Nm3 oxygen through bottom tuyeres. The directional analysis of the molten pig iron showed a carbon content of 3.9 wt.% , a silicone content of about 0.3 wt.% and residual iron. After refining, during which, departing from a bath temperature of 1470 C, a final temperature of 1620 C was reached due to the exothermic reaction occurring, the liquid steel bath had a carbon content of 0.3 wt.% =, a silicone content of 0.003-% and residual iron.
After this, 2 tons of liquid steel slag were charged onto that liquid steel bath. The steel slag was characterized by the following analysis:
Steel slag wt.%
CaO 48.6 Si02 19.1 A1203 2.2 M O 3.2 Ti02 1.5 FeO 22.7 MnO 2.7 CaO/Si02 2.5 Due to the relatively low bath carbon content of the steel bath present, the reduction reaction of the metal oxides contained in the steel slag involves substantially fewer mass conversions immediately upon the addition of the liquid steel slag. If pig iron were directly charged in the respective quantitative ratios, high amounts of CO would be released quickly, which might lead to intensive slag foaming or slag spitting.
After the charging of the steel slag onto the steel bath, temperature equalization between slag and metal bath is effected so as to enable possibly solid slag portions to be completely reconverted into the liquid state. Temperature equalization results in temperatures of about 1500 C.
After temperature equalization had been completed, 580 kg coal were blown into the steel bath at a blowing rate of 25 kg/min;
additionally introduced were 370 kg quartz sand at a rate of 24 kg/min and 535 kg bauxite at a rate of 28 kg/min.
A metal bath containing 4.5 wt.% dissolved carbon at a temperature of about 1490 C remained at the end of the desired reduction reaction. Depending on the corrective substances selected and the composition of the steel slag, the pig iron thus formed back naturally also may contain respective other metals than iron.
By means of the corrective substances, the desired target basicity as appears desirable for the cement-technological further use of the treated slag was adjusted, on the one hand, while, at the same time effecting a reduction of the metal oxides to the following directional analysis of the treated steel slag.
Treated steel slag wt.%
CaO 44.7 Si02 34.6 A-1203 14.8 M90 2.9 Ti02 1.8 FeO 0.9 MnO 0.3 CaO/Si02 1.3 The thus recovered treated steel slag could be granulated in water and used as a grinding additive in composite cements.
The heat formed during decarburization, i.e. burning of carbon, enables the heating and melting of the corrective substances required for the adjustment of the desired target basicity and the adjustment of the desired composition aimed at a cement-technologically usable grinding additive. An undesiredly high temperature level optionally developing may again be reduced to the desired reduction temperature by the addition of cooling scrap, fine ores or charging substances derived from the direct reduction of iron (DRI, HBI), thus allowing additional iron to be introduced into the metal bath.
To the extent it appears necessary, the carbon monoxide formed in the reduction may be afterburned above the slag bath, thus enabling the simultaneous processing of an elevated amount of acidic fine ores without any additional introduction of energy.
CaO 44.7 Si02 34.6 A-1203 14.8 M90 2.9 Ti02 1.8 FeO 0.9 MnO 0.3 CaO/Si02 1.3 The thus recovered treated steel slag could be granulated in water and used as a grinding additive in composite cements.
The heat formed during decarburization, i.e. burning of carbon, enables the heating and melting of the corrective substances required for the adjustment of the desired target basicity and the adjustment of the desired composition aimed at a cement-technologically usable grinding additive. An undesiredly high temperature level optionally developing may again be reduced to the desired reduction temperature by the addition of cooling scrap, fine ores or charging substances derived from the direct reduction of iron (DRI, HBI), thus allowing additional iron to be introduced into the metal bath.
To the extent it appears necessary, the carbon monoxide formed in the reduction may be afterburned above the slag bath, thus enabling the simultaneous processing of an elevated amount of acidic fine ores without any additional introduction of energy.
Claims (18)
1. A method for treating slags having iron oxide contents of greater than 5 percent by weight to form iron by reduction, comprising the steps of:
charging the slags having iron oxide contents of greater than 5 percent by weight onto a steel bath having a carbon content of less than 1.5 percent by weight; and adding carbon or carbon carriers, or a combination thereof, into said steel bath, whereby said steel bath is carburized to above 2.0 percent carbon by weight.
charging the slags having iron oxide contents of greater than 5 percent by weight onto a steel bath having a carbon content of less than 1.5 percent by weight; and adding carbon or carbon carriers, or a combination thereof, into said steel bath, whereby said steel bath is carburized to above 2.0 percent carbon by weight.
2. A method according to claim 1, wherein the slags are steel works slags.
3. A method according to claim 1 or 2, wherein the slags are mixed with other slags.
4. A method according to any one of claims 1 to 3, wherein said slags are charged onto a steel bath having a carbon content of less than 0.5 percent carbon by weight.
5. A method according to any one of claims 1 to 4, wherein said steel bath is carburized to above 2.5 percent carbon by weight.
6. A method according to any one of claims 1 to 5, wherein a pig iron bath is provided and refined with oxygen to a carbon content of less than 0.5 percent carbon by weight, whereby a bath temperature of above 1570° C. is provided, liquid steel slag is charged onto the refined steel bath, and carbon is introduced into the bath after a temperature equalization, wherein at least one SiO2-containing corrective substance and/or at least one Al2O3-containing corrective substance are added in order to lower the basicity to a value less than 1.5, and to adjust an Al2O3 content of greater than ten percent by weight, respectively.
7. A method according to claim 6, wherein said at least one SiO2-containing corrective substance is at least one of the group consisting of blast furnace slag and quartz sand.
8. A method according to claim 6, wherein said Al2O3-containing corrective substance is bauxite.
9. A method according to claim 6, wherein said bath temperature is adjusted to about 1620° C.
10. A method according to any one of claims 1 to 9, wherein the basicity, defined as the ratio CaO/SiO2, is adjusted to 1.1 to 1.4 and the carbon content of the steel bath is adjusted to greater than 2.5 percent carbon by weight.
11. A method according to any one of claims 1 to 10, wherein the slags are added to the bath at a weight quantity ratio, defined as weight of slags/weight of the steel bath, of 1:3 to 1:6.
12. A method according to claim 11, wherein the weight of slags/weight of the steel bath is about 1:4.
13. A method according to any one of claims 1 to 12, wherein quartz sand in amounts ranging from 150 to 250 kg/ton steel slag, and bauxite in amounts ranging from 200 to 300 kg/ton steel slag, are added.
14. A method according to any one of claims 1 to 13, wherein fine ores or iron oxide carriers are added to the molten slag mixtures in order to adjust the iron oxide content to greater than 8 percent by weight.
15. A method according to any one of claims 1 to 14, wherein the addition of iron oxide carriers after the addition of the molten slags or slag mixtures onto the steel bath, at least partially is effected at the same time as the carburization of the steel bath.
16. A method according to claim 15, wherein the iron oxide carriers comprise of acidic gangue weak ores or fine ores, or any combination thereof.
17. A method according to any one of claims 1 to 16, wherein corrective substances containing CaO, Al2O3, and/or SiO2 are added to the molten slags or slag mixtures.
18. A method according to any one of claims 1 to 17, wherein an additive comprising cooling scrap, fine ores or sponge iron, or any combination thereof, is melted down in the metal bath during or after refining.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ATGM65/2000 | 2000-01-28 | ||
| AT652000 | 2000-01-28 | ||
| PCT/AT2001/000010 WO2001055459A1 (en) | 2000-01-28 | 2001-01-18 | Method for treating slags or slag mixtures on an iron bath |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2398344A1 CA2398344A1 (en) | 2001-08-02 |
| CA2398344C true CA2398344C (en) | 2008-04-08 |
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ID=3480585
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2398344 Expired - Fee Related CA2398344C (en) | 2000-01-28 | 2001-01-18 | Method for treating slags or slag mixtures on an iron bath |
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| Country | Link |
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| US (1) | US6843828B2 (en) |
| EP (1) | EP1252343B1 (en) |
| JP (1) | JP4249417B2 (en) |
| KR (1) | KR100580347B1 (en) |
| CN (1) | CN1292080C (en) |
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| CZ (1) | CZ297883B6 (en) |
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| ES (1) | ES2203588T3 (en) |
| HU (1) | HUP0203820A2 (en) |
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| PT (1) | PT1252343E (en) |
| RU (1) | RU2238331C2 (en) |
| SK (1) | SK286013B6 (en) |
| TW (1) | TW533243B (en) |
| UA (1) | UA74810C2 (en) |
| WO (1) | WO2001055459A1 (en) |
| ZA (1) | ZA200205111B (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT412283B (en) * | 2003-05-16 | 2004-12-27 | Voest Alpine Ind Anlagen | METHOD FOR RECYCLING SLAG |
| AT412723B (en) * | 2003-06-30 | 2005-06-27 | Patco Engineering Gmbh | METHOD FOR CONDITIONING SLAGS AND DUST FROM STAINLESS STEEL PRODUCTION |
| CA2554805A1 (en) * | 2004-01-30 | 2005-08-11 | Technological Resources Pty. Limited | Ironmaking and steelmaking |
| ATE378429T1 (en) * | 2004-05-18 | 2007-11-15 | Holcim Ltd | METHOD FOR REDUCING CR FROM METALLURGICAL SLAGS CONTAINING CR |
| CN102019286B (en) * | 2010-12-13 | 2011-11-09 | 济南鲍安环保技术开发有限公司 | Method for treating steel slag tailings subjected to magnetic separation |
| KR101257054B1 (en) | 2011-06-28 | 2013-04-22 | 현대제철 주식회사 | Method for manufacturing scrap of electric furnace using sludge |
| EP2759606B1 (en) | 2012-06-27 | 2016-11-16 | Nippon Steel & Sumitomo Metal Corporation | Steel slag reduction equipment and steel slag reduction system |
| BR112016001146B1 (en) | 2013-07-24 | 2020-03-03 | Nippon Steel Corporation | EXHAUST GAS TREATMENT METHOD AND EXHAUST GAS TREATMENT INSTALLATION |
| WO2015011911A1 (en) * | 2013-07-25 | 2015-01-29 | Ｊｆｅスチール株式会社 | Granulated blast furnace slag for use as cement starting material and screening method for same |
| CN103710480B (en) * | 2013-12-06 | 2016-01-20 | 济南鲍德炉料有限公司 | A kind of production method of liquid steel slag waste heat reducing iron ore |
| KR102186375B1 (en) | 2016-12-16 | 2020-12-03 | 닛폰세이테츠 가부시키가이샤 | Electric furnace |
| EP3557170A4 (en) | 2016-12-16 | 2020-05-13 | Nippon Steel Corporation | Electric furnace |
| DE102017119675B4 (en) * | 2017-08-28 | 2019-07-04 | Voestalpine Stahl Gmbh | Process for the treatment of slag |
| CN111440918A (en) * | 2020-04-07 | 2020-07-24 | 包头钢铁（集团）有限责任公司 | Method for defoaming dephosphorization residues by utilizing recycled resources |
| JP7128602B1 (en) | 2022-03-11 | 2022-08-31 | 山田 榮子 | Scrap metal melting method with less industrial waste |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA993661A (en) * | 1972-02-15 | 1976-07-27 | Nils F. Tiberg | Method of environment-protective and economic recovery of metallurgical slags |
| US4304598A (en) * | 1980-09-19 | 1981-12-08 | Klockner-Werke Ag | Method for producing steel from solid, iron containing pieces |
| NZ271025A (en) * | 1993-09-07 | 1997-01-29 | Holderbank Financ Glarus | Process for making steel and hydraulically active binders using slags rich in iron oxide |
| HRP970303B1 (en) * | 1996-06-05 | 2002-06-30 | Holderbank Financ Glarus | Method for making pozzolans, synthetic blast-furnance slag, belite or alite clinkers, and pig-iron alloys, from oxidic slag and a device for implementing this method |
| ATE377659T1 (en) | 1997-09-15 | 2007-11-15 | Holcim Ltd | METHOD FOR PROCESSING STEEL SLAG AND IRON CARRIERS TO OBTAIN PIG IRON AND ENVIRONMENTALLY FRIENDLY SLAG |
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2001
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- 2001-01-18 JP JP2001554488A patent/JP4249417B2/en not_active Expired - Fee Related
- 2001-01-18 DE DE50100439T patent/DE50100439D1/en not_active Expired - Lifetime
- 2001-01-18 ES ES01901010T patent/ES2203588T3/en not_active Expired - Lifetime
- 2001-01-18 TW TW90101178A patent/TW533243B/en not_active IP Right Cessation
- 2001-01-18 MX MXPA02007083A patent/MXPA02007083A/en active IP Right Grant
- 2001-01-18 HU HU0203820A patent/HUP0203820A2/en unknown
- 2001-01-18 CN CNB018042724A patent/CN1292080C/en not_active Expired - Fee Related
- 2001-01-18 RU RU2002123053A patent/RU2238331C2/en not_active IP Right Cessation
- 2001-01-18 KR KR1020027009591A patent/KR100580347B1/en not_active IP Right Cessation
- 2001-01-18 PT PT01901010T patent/PT1252343E/en unknown
- 2001-01-18 EP EP01901010A patent/EP1252343B1/en not_active Expired - Lifetime
- 2001-01-18 CA CA 2398344 patent/CA2398344C/en not_active Expired - Fee Related
- 2001-01-18 US US10/182,057 patent/US6843828B2/en not_active Expired - Lifetime
- 2001-01-18 AU AU26522/01A patent/AU778627B2/en not_active Ceased
- 2001-01-18 CZ CZ20022782A patent/CZ297883B6/en not_active IP Right Cessation
- 2001-01-18 UA UA2002075481A patent/UA74810C2/en unknown
- 2001-01-18 SK SK956-2002A patent/SK286013B6/en not_active IP Right Cessation
- 2001-01-18 WO PCT/AT2001/000010 patent/WO2001055459A1/en active IP Right Grant
- 2001-01-18 PL PL356415A patent/PL194977B1/en not_active IP Right Cessation
- 2001-01-25 AR ARP010100315 patent/AR027285A1/en not_active Application Discontinuation
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| WO2001055459A1 (en) | 2001-08-02 |
| CZ20022782A3 (en) | 2003-03-12 |
| CN1292080C (en) | 2006-12-27 |
| CZ297883B6 (en) | 2007-04-18 |
| US6843828B2 (en) | 2005-01-18 |
| RU2002123053A (en) | 2004-02-20 |
| AR027285A1 (en) | 2003-03-19 |
| AU778627B2 (en) | 2004-12-16 |
| CN1401009A (en) | 2003-03-05 |
| US20030140732A1 (en) | 2003-07-31 |
| JP2003520899A (en) | 2003-07-08 |
| PL356415A1 (en) | 2004-06-28 |
| JP4249417B2 (en) | 2009-04-02 |
| SK9562002A3 (en) | 2003-04-01 |
| MXPA02007083A (en) | 2004-09-06 |
| KR20020090212A (en) | 2002-11-30 |
| DE50100439D1 (en) | 2003-09-04 |
| UA74810C2 (en) | 2006-02-15 |
| BR0107801B1 (en) | 2009-01-13 |
| EP1252343B1 (en) | 2003-07-30 |
| PT1252343E (en) | 2003-12-31 |
| RU2238331C2 (en) | 2004-10-20 |
| AU2652201A (en) | 2001-08-07 |
| HUP0203820A2 (en) | 2003-04-28 |
| ZA200205111B (en) | 2003-12-31 |
| TW533243B (en) | 2003-05-21 |
| PL194977B1 (en) | 2007-07-31 |
| CA2398344A1 (en) | 2001-08-02 |
| ES2203588T3 (en) | 2004-04-16 |
| BR0107801A (en) | 2002-10-22 |
| SK286013B6 (en) | 2008-01-07 |
| EP1252343A1 (en) | 2002-10-30 |
| KR100580347B1 (en) | 2006-05-16 |
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