CN115232894B - Method for extracting pure iron from iron oxide hot slag by utilizing AOD furnace or ladle - Google Patents
Method for extracting pure iron from iron oxide hot slag by utilizing AOD furnace or ladle Download PDFInfo
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 261
- 239000002893 slag Substances 0.000 title claims abstract description 233
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 title claims abstract description 189
- 229910052742 iron Inorganic materials 0.000 title claims abstract description 129
- 238000000034 method Methods 0.000 title claims abstract description 50
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 100
- 230000009467 reduction Effects 0.000 claims abstract description 34
- 239000011261 inert gas Substances 0.000 claims abstract description 25
- 238000007670 refining Methods 0.000 claims abstract description 23
- 238000003756 stirring Methods 0.000 claims abstract description 23
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 claims abstract description 18
- 238000007664 blowing Methods 0.000 claims abstract description 12
- 238000000746 purification Methods 0.000 claims abstract description 9
- 238000010079 rubber tapping Methods 0.000 claims abstract description 9
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 22
- 238000003723 Smelting Methods 0.000 claims description 22
- 230000008569 process Effects 0.000 claims description 22
- 229910000519 Ferrosilicon Inorganic materials 0.000 claims description 20
- 239000000571 coke Substances 0.000 claims description 15
- 239000003795 chemical substances by application Substances 0.000 claims description 14
- 229910052759 nickel Inorganic materials 0.000 claims description 14
- UGKDIUIOSMUOAW-UHFFFAOYSA-N iron nickel Chemical compound [Fe].[Ni] UGKDIUIOSMUOAW-UHFFFAOYSA-N 0.000 claims description 13
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 11
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 10
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 10
- 239000004571 lime Substances 0.000 claims description 10
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 2
- 239000010436 fluorite Substances 0.000 claims description 2
- 238000011010 flushing procedure Methods 0.000 claims description 2
- 239000002994 raw material Substances 0.000 abstract description 18
- 229910000831 Steel Inorganic materials 0.000 abstract description 12
- 239000010959 steel Substances 0.000 abstract description 12
- -1 iron group metals Chemical class 0.000 abstract description 3
- 229910052751 metal Inorganic materials 0.000 abstract description 2
- 239000002184 metal Substances 0.000 abstract description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 14
- 239000000956 alloy Substances 0.000 description 12
- 238000004519 manufacturing process Methods 0.000 description 11
- 229910045601 alloy Inorganic materials 0.000 description 10
- 239000011651 chromium Substances 0.000 description 10
- 239000000463 material Substances 0.000 description 9
- 229910052799 carbon Inorganic materials 0.000 description 8
- 229910052757 nitrogen Inorganic materials 0.000 description 8
- 239000010935 stainless steel Substances 0.000 description 7
- 229910001220 stainless steel Inorganic materials 0.000 description 7
- 229910052804 chromium Inorganic materials 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- 229910052698 phosphorus Inorganic materials 0.000 description 5
- 238000011946 reduction process Methods 0.000 description 5
- 229910052717 sulfur Inorganic materials 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 239000011573 trace mineral Substances 0.000 description 5
- 235000013619 trace mineral Nutrition 0.000 description 5
- 238000009749 continuous casting Methods 0.000 description 4
- QDOXWKRWXJOMAK-UHFFFAOYSA-N dichromium trioxide Chemical compound O=[Cr]O[Cr]=O QDOXWKRWXJOMAK-UHFFFAOYSA-N 0.000 description 4
- 238000007599 discharging Methods 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 3
- 238000003556 assay Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000005070 sampling Methods 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- 229910001018 Cast iron Inorganic materials 0.000 description 2
- 229910000640 Fe alloy Inorganic materials 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 241001062472 Stokellia anisodon Species 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 239000002826 coolant Substances 0.000 description 2
- 230000003009 desulfurizing effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- 238000009847 ladle furnace Methods 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 239000011819 refractory material Substances 0.000 description 2
- 238000009991 scouring Methods 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- PMVSDNDAUGGCCE-TYYBGVCCSA-L Ferrous fumarate Chemical compound [Fe+2].[O-]C(=O)\C=C\C([O-])=O PMVSDNDAUGGCCE-TYYBGVCCSA-L 0.000 description 1
- QJVKUMXDEUEQLH-UHFFFAOYSA-N [B].[Fe].[Nd] Chemical compound [B].[Fe].[Nd] QJVKUMXDEUEQLH-UHFFFAOYSA-N 0.000 description 1
- 239000011449 brick Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010891 electric arc Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- XWHPIFXRKKHEKR-UHFFFAOYSA-N iron silicon Chemical compound [Si].[Fe] XWHPIFXRKKHEKR-UHFFFAOYSA-N 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910001172 neodymium magnet Inorganic materials 0.000 description 1
- 238000011112 process operation Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000010183 spectrum analysis Methods 0.000 description 1
Classifications
-
- 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
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B11/00—Making pig-iron other than in blast furnaces
-
- 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
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
The invention belongs to the technical field of metallurgical iron group metals, and particularly relates to a method for refining pure iron from iron oxide hot slag by utilizing an AOD furnace or a ladle. Adding a slag former into the bottom of an AOD furnace or the bottom of a steel ladle, and then adding ferric oxide hot slag; blowing inert gas into the AOD furnace or the ladle for stirring; adding a reducing agent and a slag former into an AOD furnace or a ladle for multiple times to ensure that the iron temperature in the furnace reaches 1600-1650 ℃, deslagging, taking slag samples and/or iron samples, analyzing the alkalinity of the slag samples and the iron content in the slag samples and/or the iron samples, and if the iron content in the furnace reaches more than 99% and the alkalinity is between 2 and 3, obtaining the tapping requirement; otherwise, reducing agent and slag former are added for reduction and purification. The invention uses ferric oxide hot slag as raw material, and uses AOD furnace or ladle to directly reduce and refine to obtain pure iron, thus solving the problem of difficult treatment of a large amount of ferric oxide slag.
Description
Technical Field
The invention belongs to the technical field of metallurgical iron group metals, and particularly relates to a method for refining pure iron from iron oxide hot slag by utilizing an AOD furnace or a ladle.
Background
Iron is the most widely used raw material and the most abundant iron ore of productivity in the industrial production at present, is an international commodity, strategic material, belongs to the economic pulse and the like, and is one of the main means for producing iron by utilizing iron ore.
The refined pure iron in the metallurgical industry at the present stage is mainly produced by methods such as an arc furnace, an oxygen converter, external refining and the like, the pure iron produced by the methods is mainly industrial pure iron, and the production raw materials are mainly alloy materials such as iron ore, scrap iron return materials and the like; in the same field, the process method for producing pure iron by adding a reducing agent by using iron oxide slag as a raw material is not used for a while.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a method for refining pure iron from iron oxide hot slag by utilizing an AOD furnace or a ladle, which solves the recycling problem of the iron oxide slag to the maximum extent and improves the self-derived value of the iron oxide slag.
In order to achieve the above object, the present invention provides a method for refining pure iron from iron oxide slag using an AOD furnace or ladle, comprising the steps of:
(1) Adding slag former: adding a slag former into the bottom of an AOD furnace or the bottom of a ladle to ensure the alkalinity in the smelting process and simultaneously avoid flushing a furnace lining when adding hot slag of ferric oxide;
(2) Hot slag of iron oxide is added: adding hot iron oxide slag into an AOD furnace or a ladle of a slag former at the bottom of the step (1); blowing inert gas into the AOD furnace or the ladle for stirring;
(3) Adding reducing agent and slag forming agent in batches: adding a reducing agent and a slag former into the AOD furnace or the ladle obtained in the step (2) for multiple times, blowing inert gas into the AOD furnace or the ladle for stirring, and after the reducing agent and the slag former are added, making the iron temperature in the furnace reach 1600-1650 ℃, deslagging, taking slag samples and/or iron samples, analyzing the alkalinity of the slag samples and the iron content in the slag samples and/or the iron samples, and if the iron content in the furnace reaches more than 99% and the alkalinity is between 2 and 3, obtaining the iron tapping requirement; otherwise, reducing agent and slag former are added for reduction and purification.
Preferably, the mass of the slag former added in the step (1) is 0.8% -1.2% of the capacity of the AOD furnace or ladle.
Preferably, the iron oxide hot slag in the step (2) is an associated product iron oxide hot slag for refining high nickel matte or high nickel iron.
Preferably, in the step (2), hot iron oxide slag discharged during the refining of the high nickel matte or the high nickel iron is directly collected and then is added into the AOD furnace or the ladle; the temperature of the iron oxide hot slag at the time of blending is not lower than 1400 ℃, and more preferably not lower than 1500 ℃.
Preferably, the iron oxide hot slag comprises the following components in percentage by mass: siO (SiO) 2 ：2％-7％；Al 2 O 3 ：0.01％-1.5％；CaO：15％-35％；MgO：2％-8％；Fe 2 O 3 ：≥50％；Cr 2 O 3 ：＜1％。
Preferably, for an AOD furnace, step (2) is stirred using a side lance side blown inert gas; and (3) stirring the ladle by using a bottom gun to blow inert gas.
Preferably, the inert gas is supplied in an amount of 90-110m in step (2) 3 A/min; the inert gas supply amount in the step (3) is 90-110m 3 /min。
Preferably, the mass ratio of the reducing agent added for the first time in the step (3) to the slag former is 1:2.5-3.2, and the reducing agent added for the first time accounts for 2% -3% of the mass of the hot slag of the ferric oxide added in the step (3).
Preferably, in the step (3), the reducing agent and the slag former are continuously added for reduction and purification, specifically:
when the alkalinity in the furnace is between 2 and 3, the iron oxide content in the slag sample is higher than 15 percent or the iron content in the iron sample is less than 99 percent, adding the reducing agent and the slag forming agent again according to the mass ratio of 1:2.5-3.2, wherein the mass of the added reducing agent is 88-92 percent of the mass of the reducing agent added last time;
when the alkalinity in the furnace is less than 2, simultaneously adding the reducing agent and the slag former again according to the mass ratio of 0.8:3.1-3.3, wherein the added reducing agent is 75-85% of the mass of the reducing agent added for the first time;
when the alkalinity in the furnace is greater than 3, simultaneously adding the reducing agent and the slag former again according to the mass ratio of 1.3:2.6-2.8, wherein the added reducing agent is 1.2-1.4 times of the mass of the reducing agent added for the first time.
Preferably, the slag former is lime fluorite; the reducing agent is ferrosilicon and/or coke; further preferred is a mixed reducing agent of ferrosilicon and coke, wherein ferrosilicon accounts for 1/4 or more of the mass of the mixed reducing agent.
The method for extracting the pure iron from the iron oxide hot slag by utilizing the AOD furnace or the ladle has no precedent in the industry, breaks through innovation, reduces smelting reduction time, improves recycling efficiency of the iron oxide slag, and has simple equipment and process operation and low smelting cost.
In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:
(1) The invention provides a method for extracting pure iron from iron oxide hot slag by utilizing an AOD furnace or a ladle, which uses the iron oxide hot slag as a raw material to reduce the iron into pure iron in the AOD furnace or the ladle. In the preferred embodiment, a large amount of iron oxide hot slag generated by blowing refined high nickel iron is used as a raw material, so that the problem of difficult treatment of a large amount of iron oxide slag generated by producing high nickel matte/high nickel iron is solved, and the slag is changed into iron after reduction.
(2) The invention uses the process reform of reducing the ferric oxide hot slag discharged by smelting high nickel iron by an AOD furnace, compared with the production cycle of an electric arc furnace and a converter, the process greatly shortens the refining time and the production cost of pure iron, the process can be operated and completed on the basis of the existing equipment, the refining time of pure iron is 80 minutes on average, the smelting time is greatly reduced compared with the original process in the industry through inquiry, and the high nickel matte is purified by using the slag of the slag material of the associated product as the raw material, only the cost of a reducing agent and a slag former is generated, and the same industry is not favored.
(3) The invention is characterized in that the early-stage group members of the process are in line with the development spirit of the old innovation, the AOD furnace is utilized to provide sufficient reducing atmosphere, the coke is utilized to reduce the use cost of the reducing agent, through one-time test and the spectrum analysis of the finished product sample, the assay analysis of the process slag sample is carried out, the proper material proportion and the reduction rule are searched out, and the C, si element in the finished product component is required to be controlled so as not to be capable of controlling the inner control range of the ultra-pure iron component.
(4) The invention is summarized by test production, the control of the reduction temperature is the key point of operation, which is the main reason of adding the reducing agent in batches, the excessive addition of the reducing agent at one time causes the exothermic reaction to be too high in temperature above the bearable range of the refractory material, the reduction temperature is controlled within the range of 1600-1650 ℃, and the too low temperature is unfavorable for reducing Fe in slag 2 O 3 The iron yield in the slag is low, the temperature is too high, corrosion to the refractory material of the AOD furnace is serious, the overall furnace life is reduced, and the smelting cost is increased.
(5) The traditional method has high requirements on smelting equipment, the smelting cost of a VOD furnace is increased, the process adopts an AOD furnace for direct reduction fully, the casting of a pig machine is utilized as raw material pure iron, if continuous casting production is required, the direct tapping of a ladle into an LF furnace for calcium treatment and deoxidation can meet the continuous casting production, and the production flow is easier to operate than the traditional production process.
(6) The average slag yield of high nickel iron produced by each smelting is about 350 tons, and the pure iron accounting for about 30 percent of the slag yield can be produced by adopting the process to smelt the partial iron oxide hot slag, so that the produced resources are reasonably utilized and the slag treatment problem is solved.
(7) The pure iron produced by the method is mainly an industrial pure iron production raw material mainly an alloy material such as iron ore, waste iron return material and the like, the pure iron has high requirements on harmful element S element, and the traditional process has difficult treatment on the S element, and compared with the process which utilizes an AOD furnace to react with sufficient stirring force of gas and is matched with alkaline slag, the S removal effect is obvious; the process for producing pure iron by adding the reducing agent is innovative, and solves the problem of difficult treatment of a large amount of iron oxide slag generated by producing high-nickel iron by utilizing an AOD furnace reaction.
(8) The invention uses a large amount of ferric oxide hot slag generated by refining high nickel iron blowing as raw materials to be reduced into pure iron in an AOD furnace or a ladle, and the pure iron obtained by reduction can be used as important raw materials for smelting precision alloys, high-temperature alloys, ultra-low carbon stainless steel, electrothermal alloys and the like.
Drawings
FIG. 1 is a flow chart of a method of refining pure iron from iron oxide slag using an AOD furnace or ladle according to the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
The invention provides a method for refining pure iron from iron oxide slag by utilizing an AOD furnace or a ladle, which is shown in figure 1 and comprises the following steps:
(1) Adding slag former: adding a slag former into the bottom of an AOD furnace or the bottom of a ladle; according to the invention, the slag former is added into the AOD furnace bottom or the ladle furnace bottom in advance, so that on one hand, the slag former needs to be melted for a sufficient time, and the sufficient time can be provided for melting the slag former in advance to ensure the alkalinity in the smelting process; meanwhile, the scouring damage of the AOD furnace lining or the ladle furnace lining caused by directly adding the iron oxide slag can be avoided.
(2) Adding iron oxide slag: adding iron oxide slag into the AOD furnace or ladle obtained in the step (1); blowing inert gas into the AOD furnace or the ladle for stirring;
(3) Adding reducing agent and slag forming agent in batches: adding a reducing agent and a slag former into the AOD furnace or the ladle obtained in the step (2) for multiple times, blowing inert gas into the AOD furnace or the ladle for stirring, and after the reducing agent and the slag former are added, making the iron temperature in the furnace reach 1600-1650 ℃, deslagging, taking slag samples and/or iron samples, analyzing the alkalinity of the slag samples and the iron content in the slag samples and/or the iron samples, and if the iron content in the furnace reaches more than 99% and the alkalinity is between 2 and 3, obtaining the iron tapping requirement; otherwise, reducing agent and slag discharging agent are continuously added for reduction and purification.
Before the hot slag of iron oxide is added into the furnace, in order to prevent scouring of the bottom of the AOD furnace or the ladle, in particular, a slag former is added into the furnace in advance for bottom filling. However, too many bedding pieces are not needed, otherwise the temperature of the hot slag of the ferric oxide is greatly reduced. In some embodiments, step (1) is performed with a slag former in an amount of 0.8% to 1.2% of the AOD furnace or ladle bath capacity. For example, the capacity of a molten pool of an AOD furnace is 100 tons, and 1 ton of slag former can be added in advance.
The amount of the ferric oxide slag which can be added in the step (2) is not more than the accommodating amount of an AOD furnace or a ladle molten pool. In some embodiments, the iron oxide slag of step (2) is an associated product of refining high nickel matte or high nickel iron. The method comprises the following steps of (2) directly collecting iron oxide slag discharged during the refining of high nickel matte or high nickel iron, and then adding the iron oxide slag into the AOD furnace or ladle; the temperature of the iron oxide slag is not lower than 1400 ℃, preferably not lower than 1500 ℃ when blended. The invention directly collects and utilizes the iron oxide slag discharged during refining the high nickel iron, receives the iron oxide slag by a metallurgical vessel, and then adds the iron oxide slag into an AOD furnace or a ladle for reduction operation. If the slag yield of the upstream iron oxide hot slag can not be increased by filling the AOD furnace or the ladle molten pool at one time, the iron oxide hot slag can be added in stages for reduction and refining according to the method of the invention.
In some embodiments, the iron oxide slag comprises, by mass: siO (SiO) 2 ：2％-7％；Al 2 O 3 ：0.01％-1.5％；CaO：15％-35％；MgO：2％-8％；Fe 2 O 3 : more than or equal to 50 percent and less than 100 percent; cr (Cr) 2 O 3 : the content of the trace elements is less than 1%, so that the other trace elements of the pure iron are not out of standard, and the lower the other trace elements are, the better.
For an AOD furnace, the step (2) can be carried out by using a side gun to blow inert gas for stirring; for the ladle, the step (2) can use a bottom gun to blow inert gas for stirring. The supply amount of the inert gas in the step (2) is 90-110m 3 A/min; the inert gas supply amount in the step (3) is 90-110m 3 /min。
According to the amount of the added ferric oxide slag, a proper reducing agent is proportioned, inert gas is supplied by utilizing an AOD furnace side gun or a ladle bottom gun, and the ferric oxide is fully reduced in the slag; the reducing agent is fed in batches by utilizing the principle of reducing heat release, so that the problem that the temperature in the furnace cannot be controlled due to rapid temperature rise caused by feeding a large amount of reducing materials at one time is avoided, and the furnace bricks of the furnace lining are seriously corroded due to the fact that the temperature is too high. In some embodiments, the mass ratio of the reducing agent added for the first time in the step (3) to the slag former is 1:2.5-3.2, and the reducing agent added for the first time is 2% -3% of the mass of the iron oxide slag added in the step (3). The slag making material and the reducing agent are added together, so that the alkalinity in the furnace can be balanced, and other trace elements in the molten iron can be taken away.
Adding a reducing agent and a slag former into an AOD furnace or a ladle for multiple times, after the reducing agent and the slag former are added in step (3), enabling the iron temperature in the furnace to reach 1600-1650 ℃, deslagging, taking slag samples and iron samples, analyzing the alkalinity of the slag samples and the iron content in the slag samples and/or the iron samples, and if the iron content in the furnace reaches more than 99% and the alkalinity is between 2 and 3, obtaining the tapping requirement; otherwise, the reducing agent and the slag former are continuously added for reduction and purification, and in order to better control the furnace temperature and reach the reduction expectation as soon as possible, in the preferred embodiment, the method can be carried out as follows:
when the alkalinity in the furnace is between 2 and 3, the iron oxide content in the slag sample is higher than 15 percent or the iron content in the iron sample is less than 99 percent, adding the reducing agent and the slag forming agent again according to the mass ratio of 1:2.5-3.2, wherein the mass of the added reducing agent is 88-92 percent of the mass of the reducing agent added last time;
when the alkalinity in the furnace is less than 2, simultaneously adding the reducing agent and the slag former again according to the mass ratio of 0.8:3.1-3.3, wherein the added reducing agent is 75-85% of the mass of the reducing agent added for the first time;
when the alkalinity in the furnace is greater than 3, simultaneously adding the reducing agent and the slag former again according to the mass ratio of 1.3:2.6-2.8, wherein the added reducing agent is 1.2-1.4 times of the mass of the reducing agent added for the first time.
After the raw materials and the slag forming agent are fed in batches, a small amount and a plurality of times, inert gas is fully stirred, a slag sample or an iron sample is taken for analysis to confirm that the iron oxide content in slag or the iron content in molten iron and the alkalinity in slag can be subjected to slag discharging operation, the waste slag is discharged, and the molten iron is left in the furnace. Repeating the above operation, adding iron oxide hot slag for the second time, adding nitrogen into the reducing agent, stirring and fully reducing to ensure that the iron temperature in the furnace reaches about 1600-1650 ℃, discharging slag, taking slag samples and/or iron samples, and testing and analyzing to confirm whether the iron content in the furnace reaches more than 99% or not, thus reaching the tapping requirement. By adopting the reduction method, the iron oxide content of 60-70% in the original iron oxide hot slag generally needs to be fully reduced by using about 20% of the reducing agent by weight, so as to meet the requirement of tapping.
The invention adds reducing agent and slag former in batches: adding a reducing agent and a slag forming agent into an AOD furnace or a ladle into which iron oxide hot slag is added for multiple times, blowing inert gas into the AOD furnace or the ladle for stirring, adjusting the use amount of ferrosilicon in the reducing agent according to the initial temperature of the iron oxide hot slag after adding the reducing agent and the slag forming agent, enabling the iron temperature in the furnace to reach 1600-1650 ℃, deslagging, sampling slag and/or iron samples, analyzing the alkalinity of the slag samples and the iron content in the slag samples and/or iron samples, and if the iron content in the furnace reaches more than 99% and the alkalinity is between 2-3, obtaining the iron tapping requirement; otherwise, reducing agent and slag former are added for reduction and purification. The iron content in the furnace can be judged indirectly according to the iron oxide content in the slag sample or directly according to the iron content in the molten iron.
In some embodiments, the slag former is lime; the reducing agent is ferrosilicon and/or coke. Preferably, a mixed reducing agent of ferrosilicon and coke is adopted, and the ferrosilicon is used as a strong reducing agent, so that the ferrosilicon can play a role in reducing ferric oxide on one hand, and is strongly exothermic in the reduction process on the other hand, thereby being beneficial to maintaining the reaction temperature in the reduction process. The proportion of ferrosilicon and coke can be determined according to the temperature of the iron oxide hot slag, and generally if the temperature of the iron oxide hot slag is higher than or equal to 1500 ℃, the mass ratio of ferrosilicon in the mixed reducing agent is 1/4; if the temperature of the iron oxide hot slag is below 1500 ℃, the ratio of ferrosilicon in the mixed reducing agent can be suitably increased, such as to 1/3.5 to 1/3.9, or adjusted according to the initial temperature of the iron oxide hot slag.
AOD furnaces are commonly used for refining stainless steel by blowing O during smelting 2 Ar or N 2 And (3) decarburizing the molten steel by using the mixed gas, adding a reducing agent, a desulfurizing agent, an iron alloy or a cooling agent and the like into a charging system to adjust the components and the temperature of the molten steel, smelting qualified stainless molten steel, discharging the stainless molten steel into a ladle, and refining the stainless molten steel in the ladle to qualified molten steel to provide finished molten steel of the continuous casting machine. The AOD furnace and the steel ladle are mature operating systems, have the advantages of simple equipment, convenient operation, strong adaptability, investment saving, low production cost and the like, can provide strong stirring force of Ar gas and N2 gas, and can be used as equipment for refining pure iron by reducing iron oxide hot slag.
The AOD furnace is generally used for pouring molten iron of a blast furnace and alloy melted on an intermediate frequency furnace into the AOD furnace through a ladle, blowing oxygen, ar or nitrogen mixed gas during smelting to decarbonize molten steel, and simultaneously adding a reducing agent, a desulfurizing agent, iron alloy or a cooling agent and the like into a charging system to adjust the composition and the temperature of the molten steel, so as to smelt qualified stainless molten steel for a continuous casting machine. The invention applies the AOD furnace to directly reduce and refine the pure iron from the iron oxide hot slag associated with high-nickel iron smelting for the first time, thereby changing waste into valuables.
Because of the variable addition of other trace elements in the iron oxide slag, the current technology classifies the output into 3 categories:
(1) the iron content reaches 99 percent, other microelements exceeding the requirements of raw material pure iron and industrial pure iron are divided into inferior pure iron, and the inferior pure iron can be used for smelting stainless steel adjusting components after cast iron;
(2) the iron content reaches more than 99.5%, other microelements reach the requirement of raw material pure iron, and the method is divided into alloy smelting and stainless steel smelting in the application field of the raw material pure iron, and is mainly used for producing products such as neodymium iron boron, aluminum nickel cobalt, electrical alloy, high-temperature and precise alloy and the like;
(3) the iron content reaches 99.6 to 99.8 percent or more, the total impurity content is less than 0.2 percent, and other elements reach the requirement of the internal control range of industrial pure iron, and the method is divided into industrial pure iron, and can be used for smelting important raw materials such as precise alloy, high-temperature alloy, ultra-low carbon stainless steel, electrothermal alloy and the like after being continuously cast into square billets.
The process reduces the iron chemical reaction equation and the process alkalinity control condition:
3C+Fe 2 O 3 =high temperature=2fe+3co+.
Si+2feo=high temperature=sio 2 +2Fe
Process basicity is required to be controlled at ρ=2-3.
The following are examples:
example 1
Adding slag amount and components: the slag is added in the example at one time, the slag adding amount is 45T, and the components are SiO 2 ：3.97％，Al 2 O 3 ：0.89％，CaO：16.89％，MgO：4.22％，Ni：0.028％，Cr 2 O 3 ：0.75％，Fe 2 O 3 :72.58 percent and the temperature of the iron oxide slag is 1525 ℃.
The AOD high-level bin is used for standby reducing agent (ferrosilicon and coke), slag former (lime) and 1 ton slag former is added to the bottom of the furnace before slag adding operation;
after adding iron oxide slag, the AOD furnace side gun supplies inert gas (nitrogen) with the supply amount of 100m 3 And/min, fully providing stirring force;
adding the reducing agent and the slagging agent from a high-level bin at the same time after the proper stirring strength is confirmed, adding the reducing agent and the slagging agent according to the proportion of 1:3, adding 45 tons of slag, wherein the adding amount of the first reducing agent ferrosilicon is 285kg of coke, the adding amount of the first reducing agent ferrosilicon is 1300kg, the adding amount of lime is 4000kg, at the moment, the assay alkalinity rho=2.55, nitrogen is fully stirred for 4-6min, then pouring the furnace to measure the temperature (1650 ℃), taking a slag sample, adding 150kg of the second reducing agent ferrosilicon into 800kg of coke, measuring the temperature (1610 ℃) to obtain the slag sample after the same inert gas is stirred for 4-6min, adding 50kg of the third reducing agent ferrosilicon into 550kg of coke, and measuring the lime to 1600kg, wherein the adding amount of the reducing agent ferrosilicon is properly reduced because the slag amount is reduced, reducing nitrogen is reduced for 5min, taking the slag sample at the temperature (1643 ℃) and carrying out the last reducing agent adding, 240kg of coke and 650kg of lime after stirring is finished; 485kg of ferrosilicon, 2890kg of coke and 8930kg of lime are used in total, 4 batches of reducing agent and slag former are added, and sampling is carried out to confirm the iron content, wherein the components are Fe:99.51%, C:0.004%, P:0.005%, S:0.05%, si:0.01%, cr:0.16%, ni:0.15%. Specific reduction process data are shown in table 1:
TABLE 1
The slag of the inverted fire grate needs to be discharged cleanly, the iron can be discharged, the subsequent cast iron can be used, and the furnace is used for finely adjusting the components of smelting stainless steel.
Comparative example 1
Comparative example 1 is the same as example in that only one iron oxide slag is added for reduction, but the iron content of the reduced product is less than 99%, and the added iron oxide slag is SiO 2 ：2.97％，Al 2 O 3 ：0.87％，CaO：19.73％，MgO：4.04％，Ni：0.037％，Cr 2 O 3 ：0.63％，Fe 2 O 3 :70.68 percent and the temperature of the iron oxide slag is 1495 ℃.
The same operation as in example 1, the reduction time and temperature are basically the same, but the addition amount of the reducing agent in this example is less and the ratio of the two times of addition of the slag former is not as low as 1:2.5, and experiments find that the iron content does not reach the target of the corresponding reduction effect, and the specific addition amount and reduction conditions are as shown in the following table 2:
TABLE 2
The iron oxide in the slag is unknown before the test, the reduction allowance is also reserved, the mixture is stirred for 5min after the last material is added, sampling is carried out, the iron is selected, and the final reduction pure iron comprises the following components: fe:98.18%, C:0.003%, P:0.004%, S:0.05%, si:0.01%, cr:0.18%, ni:0.79%;
the reduced iron content of the comparative example is less than 99%, and the possible reasons for the follow-up summary are that the total addition amount of the reducing agent is insufficient, and Fe in slag is not fully contained 2 O 3 The reaction, the Fe content in the reduced molten iron is not saturated, and the ratio of the reducing agent to the slag former is 1:2.36 is lower, so that the requirement of target components is not met, and the method is subsequently applied to stainless steel smelting fine tuning components.
Example 2
Adding slag amount and components: first stage iron oxide slag composition: siO (SiO) 2 ：4.59％，Al 2 O 3 ：0.88％，CaO：26.71％，MgO：3.88％，Ni：0.045％，Cr 2 O 3 ：0.98％，Fe 2 O 3 :62.69%; the first stage is to mix 40 tons of iron oxide slag; since the upstream hot iron oxide slag yield cannot fill the AOD furnace bath at a time, this embodiment adds the hot iron oxide slag in two stages. The second stage iron oxide slag comprises the following components: siO (SiO) 2 ：4.72％，Al 2 O 3 ：0.81％，CaO：18.02％，MgO：5.73％，Ni：0.050％，Cr 2 O 3 ：0.68％，Fe 2 O 3 :69.90%; the second stage adds 32 tons of iron oxide slag; the temperature of the iron oxide slag was 1500 ℃.
Reducing agent (ferrosilicon and coke), slag former (lime) is put into a high-level bin of an AOD furnace in advance for standby, and 1 ton of slag former is added to be filled into the bottom of the furnace before slag adding operation;
after adding iron oxide slag, the AOD furnace side gun supplies inert gas (nitrogen) with the supply amount of 100m 3 And/min, fully providing stirring force;
after the proper stirring strength is confirmed, the reducing agent and the slag former are added from a high-level bin at the same time, the ratio of the reducing agent to the slag former is about 1:2.5, the slag adding amount in the first stage is 40 tons, the adding amount of the silicon iron in the first batch is 200kg, the adding amount of coke is 830kg, the adding amount of lime is 2950kg, the assay analysis alkalinity is ρ=2.91, the stirring time is about 5 minutes, the furnace is cooled down to obtain a slag sample after full reduction, the second batch of reducing agent and the slag former are added in the same proportion, the adding amount is properly reduced by 90% of the first batch, 8 batches of reducing agent and slag former are added for 4 times in the first stage and 4 times in the second stage; the amount and process iron oxide content are shown in Table 3 below.
TABLE 3 Table 3
Adjusting the addition amount of the reducing agent according to the reduction degree of the iron oxide content (shown in the table) of the slag sample and the measured temperature, preparing for secondary reduction, and repeating the steps of adding the reducing agent and the slag forming agent; slag sample components of the last time in the first stage: siO (SiO) 2 ：27.05％，Al 2 O 3 ：1.78％，CaO：57.22％，MgO：6.46％，Fe 2 O 3 :6.10%, iron-like components: fe:97.46%, C:0.148%, P:0.004%, S:0.028%. At the moment, the ferric oxide in the slag is fully reduced, and the second-time ferric oxide slag can be added for second-stage reduction;
repeating the operation to perform second-stage reduction, wherein the last slag sample component in the second stage: siO2:26.91%, al2O3:1.80%, caO:51.60%, mgO:2.76%, fe2O3:15.07%, the finished iron sample comprises: fe:99.76%, C:0.003%, P:0.004%, S:0.02%, si:0.01%, cr:0.1%, ni:0.05%;
the slag can be discharged after the components are qualified, the slag discharge operation is required to be clean without leaving slag, the slag is conveyed to a pig machine for casting, and the furnace can be used as raw material pure iron for use.
Comparative example 2
The comparative example is the same as adding the iron oxide slag twice, because the iron oxide slag is not selected for the first time of adding the iron oxide slag twiceThe iron content caused by the separation does not reach the standard, and other elements exceed the standard, and the specific components are the iron oxide slag components in the first stage: siO (SiO) 2 ：4.72％，Al 2 O 3 ：0.81％，CaO：18.02％，MgO：4.73％，Ni：0.097％，Cr 2 O 3 ：2.77％，Fe 2 O 3 :68.02%; the second stage iron oxide slag comprises the following components: siO (SiO) 2 ：6.04％，Al 2 O 3 ：0.73％，CaO：21.79％，MgO：4.55％，Ni：0.10％，Cr 2 O 3 ：0.84％，Fe 2 O 3 ：65.14％；
Reduction operation is carried out according to the operation process requirements described in example 2, the ratio of the reducing agent to the slag former is about 1:2.5-3.1, the process alkalinity is kept at rho=2-3, the reduction process is carried out in 4 batches of materials, the reduction time is controlled to be 4-6min under nitrogen stirring, and the specific process indexes are shown in the following table 4:
TABLE 4 Table 4
The case reduction process is compared with the previous test, and the finished iron sample is: fe:98.66%, C:0.003%, P:0.003%, S:0.021%, si:0.01%, cr:1.12%, ni:0.09%; the iron content of the finished product does not reach the standard of pure iron components, cr element components exceed the standard, the following summary shows that the possible reason is the particularity that chromium sesquioxide is easy to reduce and can not be removed, the follow-up selection of ferrous oxide hot slag needs to be used as raw materials by selecting the later slag for refining high nickel iron as far as possible, the Cr element in the molten iron in the earlier slag is oxidized to cause the higher chromium sesquioxide content in the slag, the earlier slag is not selected for pure iron reduction, and the iron oxide slag in the following range is obtained to be suitable for reducing pure iron to use: siO (SiO) 2 ：2％-7％；Al 2 O 3 ：0.01％-1.5％；CaO：15％-35％；MgO：2％-8％；Fe 2 O 3 : more than or equal to 50 percent is preferable; cr (Cr) 2 O 3 : preferably less than 1%.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (7)
1. A method for refining pure iron from iron oxide slag by using an AOD furnace or ladle, comprising the steps of:
(1) Adding slag former: adding a slag former into the bottom of an AOD furnace or the bottom of a ladle to ensure the alkalinity in the smelting process and simultaneously avoid flushing a furnace lining when adding hot slag of ferric oxide;
(2) Hot slag of iron oxide is added: adding hot iron oxide slag into an AOD furnace or a ladle of a slag former at the bottom of the step (1); blowing inert gas into the AOD furnace or the ladle for stirring; the iron oxide hot slag comprises the following components in percentage by mass: siO (SiO) 2 ：2%-7%；Al 2 O 3 ：0.01%-1.5%；CaO：15%-35%；MgO：2%-8%；Fe 2 O 3 ：≥50%；Cr 2 O 3 ：＜1%；
(3) Adding reducing agent and slag forming agent in batches: adding a reducing agent and a slag former into the AOD furnace or the ladle obtained in the step (2) for multiple times, blowing inert gas into the AOD furnace or the ladle for stirring, and after the reducing agent and the slag former are added, making the iron temperature in the furnace reach 1600-1650 ℃, deslagging, taking slag samples and/or iron samples, analyzing the alkalinity of the slag samples and the iron content in the slag samples and/or the iron samples, and if the iron content in the furnace reaches more than 99% and the alkalinity is between 2 and 3, obtaining the iron tapping requirement; otherwise, continuously adding a reducing agent and a slag former for reduction and purification;
the mass ratio of the reducing agent added for the first time to the slag former in the step (3) is 1:2.5-3.2, and the reducing agent added for the first time is 2% -3% of the mass of the hot slag of the ferric oxide added in the step (2);
continuously adding a reducing agent and a slag former to carry out reduction purification, wherein the reduction purification comprises the following steps:
when the alkalinity in the furnace is between 2 and 3 and the iron content in the iron sample is less than 99 percent, adding the reducing agent and the slag former again according to the mass ratio of 1:2.5 to 3.2, wherein the mass of the added reducing agent is 88 to 92 percent of the mass of the reducing agent added last time;
when the alkalinity in the furnace is less than 2, simultaneously adding the reducing agent and the slag former again according to the mass ratio of 0.8:3.1-3.3, wherein the added reducing agent is 75-85% of the mass of the reducing agent added for the first time;
when the alkalinity in the furnace is greater than 3, simultaneously adding the reducing agent and the slag former again according to the mass ratio of 1.3:2.6-2.8, wherein the added reducing agent is 1.2-1.4 times of the mass of the reducing agent added for the first time.
2. The method of claim 1, wherein the mass of the slag former charged in step (1) is 0.8% -1.2% of the AOD furnace or ladle capacity.
3. The method of claim 1, wherein the iron oxide hot slag of step (2) is an associated product of refining high nickel matte or high nickel iron.
4. The method of claim 1, wherein the step (2) is to collect the hot slag of iron oxide discharged during the refining of high nickel matte or high nickel iron directly and mix the hot slag into the AOD furnace or ladle; the temperature of the ferric oxide hot slag is not lower than 1400 ℃ when the ferric oxide hot slag is mixed.
5. The method of claim 1, wherein for the AOD furnace, step (2) is performed with stirring using a side gun side blown inert gas; and (3) stirring the ladle by using a bottom gun to blow inert gas.
6. The method according to claim 1, wherein the inert gas is supplied in the amount of 90 to 110m n/min in step (2); the supply amount of the inert gas in the step (3) is 90-110 and m W/min.
7. The method of claim 1, wherein the slag former is lime fluorite; the reducing agent is ferrosilicon and/or coke.
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| CN104789724A (en) * | 2015-03-19 | 2015-07-22 | 中南大学 | Method for extracting iron through reduction smelting of lead slag |
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| CN1365396A (en) * | 2000-04-10 | 2002-08-21 | 株式会社神户制钢所 | Method for producing reduced iron |
| CN101220413A (en) * | 2008-01-30 | 2008-07-16 | 郭长庆 | Technique for smelting ferroferrite with sponge iron |
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