CN115232894A - Method for extracting pure iron from iron oxide hot slag by using AOD furnace or ladle - Google Patents
Method for extracting pure iron from iron oxide hot slag by using 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 254
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 title claims abstract description 208
- 239000002893 slag Substances 0.000 title claims abstract description 189
- 229910052742 iron Inorganic materials 0.000 title claims abstract description 125
- 238000000034 method Methods 0.000 title claims abstract description 54
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 91
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 39
- 230000009467 reduction Effects 0.000 claims abstract description 34
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 32
- 239000010959 steel Substances 0.000 claims abstract description 32
- 239000011261 inert gas Substances 0.000 claims abstract description 26
- 238000003756 stirring Methods 0.000 claims abstract description 21
- 238000007664 blowing Methods 0.000 claims abstract description 14
- 239000000470 constituent Substances 0.000 claims abstract description 10
- 238000007599 discharging Methods 0.000 claims abstract description 10
- 238000010079 rubber tapping Methods 0.000 claims abstract description 10
- 238000000746 purification Methods 0.000 claims abstract description 9
- 238000003723 Smelting Methods 0.000 claims description 23
- 230000008569 process Effects 0.000 claims description 23
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 20
- 238000007670 refining Methods 0.000 claims description 19
- 229910000519 Ferrosilicon Inorganic materials 0.000 claims description 16
- 229910052759 nickel Inorganic materials 0.000 claims description 13
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 11
- 239000000571 coke Substances 0.000 claims description 10
- UGKDIUIOSMUOAW-UHFFFAOYSA-N iron nickel Chemical compound [Fe].[Ni] UGKDIUIOSMUOAW-UHFFFAOYSA-N 0.000 claims description 7
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 6
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 6
- 239000004571 lime Substances 0.000 claims description 6
- 229910000863 Ferronickel Inorganic materials 0.000 claims description 4
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical group [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 2
- 239000010436 fluorite Substances 0.000 claims description 2
- 238000009991 scouring Methods 0.000 claims description 2
- 238000013019 agitation Methods 0.000 claims 1
- 239000002994 raw material Substances 0.000 abstract description 17
- -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
- 238000004519 manufacturing process Methods 0.000 description 14
- 239000000956 alloy Substances 0.000 description 12
- 239000011651 chromium Substances 0.000 description 11
- 229910045601 alloy Inorganic materials 0.000 description 10
- 239000010935 stainless steel Substances 0.000 description 10
- 229910001220 stainless steel Inorganic materials 0.000 description 10
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 9
- 239000000463 material Substances 0.000 description 9
- 229910052799 carbon Inorganic materials 0.000 description 8
- 229910052804 chromium Inorganic materials 0.000 description 8
- 238000012360 testing method Methods 0.000 description 8
- 239000011573 trace mineral Substances 0.000 description 7
- 235000013619 trace mineral Nutrition 0.000 description 7
- 229910052757 nitrogen Inorganic materials 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
- 230000008901 benefit Effects 0.000 description 4
- 238000005266 casting Methods 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 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
- 239000007789 gas Substances 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 229910004298 SiO 2 Inorganic materials 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 238000010891 electric arc Methods 0.000 description 3
- 238000009847 ladle furnace Methods 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910001018 Cast iron Inorganic materials 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 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
- 238000004064 recycling Methods 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- 229910001021 Ferroalloy Inorganic materials 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
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
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- 229910001172 neodymium magnet Inorganic materials 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 238000011112 process operation Methods 0.000 description 1
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Classifications
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- 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 extracting pure iron from iron oxide hot slag by using an AOD furnace or a ladle. Adding a slagging agent into the bottom of the AOD furnace or the bottom of a steel ladle, and then adding iron oxide hot slag; blowing inert gas into the AOD furnace or the ladle for stirring; adding a reducing agent and a slagging agent into the AOD furnace or the ladle for multiple times to ensure that the iron temperature in the furnace reaches 1600-1650 ℃, discharging slag, taking a slag sample and/or an iron sample, analyzing the alkalinity of the slag sample and the iron content in the slag sample and/or the iron sample, and if the iron content in the furnace reaches more than 99 percent and the alkalinity is between 2 and 3, achieving the tapping requirement; otherwise, continuously adding the reducing agent and the slagging constituent for reduction and purification. The invention uses the hot iron oxide slag as a raw material, and uses the AOD furnace or the steel ladle to directly reduce and refine to obtain pure iron, thereby solving the problem of difficult treatment of a large amount of iron oxide slag.
Description
Technical Field
The invention belongs to the technical field of metallurgical iron group metals, and particularly relates to a method for extracting pure iron from hot iron oxide slag by using an AOD furnace or a ladle.
Background
Iron is the most widely used raw material in the current industrial production and the iron ore with the most abundant productivity is an international large commodity, strategic material and belongs to economic life, and the production of iron by using the iron ore is also one of the main means.
Refining pure iron in the metallurgical industry at the present stage is mainly produced by using an electric arc furnace, an oxygen converter and external refining and other methods, the pure iron produced by the method is mainly industrial pure iron, and the production raw materials are mainly iron ore, scrap iron return materials and other alloy materials; in the same field, a process method for producing pure iron by using iron oxide slag as a raw material and adding a reducing agent is not used temporarily.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a method for extracting pure iron from hot iron oxide slag by using an AOD furnace or a ladle, which solves the problem of recycling the iron oxide slag to the maximum extent and improves the self-derived value of the iron oxide slag.
In order to achieve the aim, the invention provides a method for refining pure iron from iron oxide slag by using an AOD furnace or a ladle, which comprises the following steps:
(1) Adding a slagging agent: adding a slag former into the bottom of the AOD furnace or the bottom of a steel ladle to ensure the alkalinity in the smelting process and avoid scouring a furnace lining when adding hot iron oxide slag;
(2) Adding hot iron oxide slag: adding hot iron oxide slag into the AOD furnace or the steel ladle added with the slagging agent at the bottom in the step (1); blowing inert gas into the AOD furnace or the ladle for stirring;
(3) Adding a reducing agent and a slagging agent in batches: adding a reducing agent and a slagging agent into the AOD furnace or steel ladle obtained in the step (2) for multiple times, blowing inert gas into the AOD furnace or steel ladle, stirring, adding the reducing agent and the slagging agent, keeping the temperature of iron in the furnace to 1600-1650 ℃, discharging slag, taking a slag sample and/or an iron sample, analyzing the alkalinity of the slag sample and the iron content in the slag sample and/or the iron sample, and if the iron content in the furnace reaches more than 99% and the alkalinity is between 2 and 3, achieving the tapping requirement; otherwise, continuously adding the reducing agent and the slagging constituent to carry out reduction purification.
Preferably, the weight of the slag former added in the step (1) is 0.8-1.2% of the capacity of the AOD furnace or the ladle.
Preferably, the hot iron oxide slag obtained in the step (2) is hot iron oxide slag which is an associated product of refining high nickel matte or high nickel iron.
Preferably, the step (2) directly collects the hot iron oxide slag discharged when the high nickel matte or high nickel iron is refined and then mixes the hot iron oxide slag into the AOD furnace or the ladle; the temperature of the hot iron oxide slag is not lower than 1400 ℃ during the blending, and is further preferably not lower than 1500 ℃.
Preferably, the iron oxide hot slag comprises the following components in percentage by mass: siO2 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 the AOD furnace, step (2) uses side lance side blowing inert gas for stirring; and (3) stirring the ladle by using inert gas blown from the bottom of a bottom gun in the step (2).
Preferably, the supply amount of the inert gas in the step (2) is 90-110m 3 Min; the supply amount of the inert gas in the step (3) is 90-110m 3 /min。
Preferably, the mass ratio of the reducing agent and the slag former added for the first time in the step (3) is 1.
Preferably, the reducing agent and the slag former are continuously added in the step (3) for reduction and purification, and the method specifically comprises the following steps:
when the alkalinity in the furnace is between 2 and 3, the content of iron oxide in the slag sample is higher than 15 percent or the content of iron in the iron sample is less than 99 percent, adding the reducing agent and the slag former again according to the mass ratio of 1:2.5-3.2, 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 to 3.1 to 3.3, wherein the added reducing agent accounts for 75 to 85 percent of the mass of the reducing agent added for the first time;
when the alkalinity in the furnace is more than 3, simultaneously adding the reducing agent and the slagging constituent again according to the mass ratio of 1.3 to 2.6 to 2.8, wherein the mass of the added reducing agent is 1.2 to 1.4 times of that of the reducing agent added for the first time.
Preferably, the slagging agent is fluorite lime; 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 and more of the mass of the mixed reducing agent.
The method for extracting pure iron from the hot iron oxide slag by using the AOD furnace or the ladle has no precedent in the same industry, breaks through innovation, reduces smelting reduction time, improves the recycling efficiency of the iron oxide slag, and has simple equipment and process operation and low smelting cost.
Generally, compared with the prior art, the technical scheme conceived by the invention has the following beneficial effects:
(1) The invention provides a method for extracting pure iron from hot iron oxide slag by using an AOD furnace or a steel ladle. In the preferred embodiment, a large amount of hot iron oxide slag generated by refining the high nickel iron is used as a raw material, so that the problem of difficult treatment of a large amount of hot 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 utilizes the technological innovation of reducing the hot iron oxide slag discharged by smelting high-nickel iron by the AOD furnace, greatly shortens the time for refining pure iron and the production cost compared with the production period of an electric arc furnace and a converter, can be operated and finished on the basis of the existing equipment, has the average time of refining pure iron of 80min, greatly reduces the smelting time compared with the original process in the industry by inquiry, only generates the cost of a reducing agent and a slag former by utilizing the associated product slag iron oxide slag as a raw material for purification, and has no prior benefit in the same industry.
(3) In the early stage of the process, the team members rely on the development spirit of old innovation, from the beginning to the end, use the AOD furnace to provide sufficient reducing atmosphere, use coke to reduce the use cost of the reducing agent, and through one-time test, spectral analysis of a finished product sample and test analysis of a process slag sample, a proper material proportion and a reduction rule are obtained, and the internal control range of C and Si elements in the finished product components cannot be controlled within the ultra-pure iron components.
(4) According to test production summary, the control of the reduction temperature is the main point of operation, which is also the main reason for adding the reducing agent in batches, the excessive addition of the reducing agent at one time causes the over-sufficient exothermic reaction, the temperature is higher than the bearing range of refractory materials, the reduction temperature is controlled within the range of 1600-1650 ℃, and the excessively low temperature is not beneficial to the Fe in the reduction slag 2 O 3 And the yield of iron in the slag is low, the temperature is too high, the corrosion to the AOD furnace refractory is serious, the whole furnace life is reduced, and the smelting cost is increased.
(5) The traditional method has high requirements on smelting equipment, the smelting cost of the VOD furnace is increased, the process adopts the AOD furnace for direct reduction, the pig casting machine is used for casting pure iron as a raw material, if continuous casting production is needed, the continuous casting production can be met by directly tapping steel and packaging into the LF furnace for calcium treatment and deoxidation, and the production flow is easier to operate than that of the traditional production process.
(6) The average slag amount produced by smelting the high-nickel iron each time is about 350 tons, and the hot iron oxide slag can produce about 30 percent of pure iron blended with the slag amount by adopting the process for smelting, thereby reasonably utilizing the produced resources and improving the slag treatment problem.
(7) Refining pure iron in the metallurgical industry at the present stage is mainly produced by using an electric arc furnace, an oxygen converter and external refining or a VOD furnace and the like, the pure iron produced by the method is mainly an industrial pure iron production raw material and mainly comprises iron ore, scrap iron return materials and other alloy materials, the requirement of the pure iron on harmful elements S is high, the traditional process is difficult to process the S element, and compared with the process, the process has the advantages that the reaction gas stirring force of the AOD furnace is sufficient, the basic furnace slag is matched, and the S removing effect is obvious; in the same field, a process method for producing pure iron by using iron oxide slag as a raw material and adding a reducing agent is not used temporarily, the process is innovated, the problem of difficult treatment of a large amount of iron oxide slag generated in the production of high-nickel iron is solved by using the AOD furnace reaction, and the slag is changed into iron after reduction.
(8) The invention uses a large amount of iron oxide hot slag generated by refining ferronickel blowing as a raw material to be reduced into pure iron in an AOD furnace or a ladle, and the pure iron obtained by reduction can be used as an important raw material 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 the method for refining pure iron from iron oxide slag by using AOD furnace or ladle according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention provides a method for extracting pure iron from iron oxide slag by using an AOD furnace or a ladle, which comprises the following steps as shown in figure 1:
(1) Adding a slagging agent: adding a slagging agent into the bottom of the AOD furnace or the bottom of the ladle furnace; according to the invention, the slagging agent is added into the AOD furnace bottom or the ladle furnace bottom in advance, on one hand, sufficient time is needed for melting the slagging agent, and on the other hand, sufficient time can be provided for melting the slagging agent by adding the slagging agent in advance so as to ensure the alkalinity in the smelting process; meanwhile, the washing 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 the steel ladle obtained in the step (1); blowing inert gas into the AOD furnace or the ladle for stirring;
(3) Adding a reducing agent and a slagging agent in batches: adding a reducing agent and a slagging agent into the AOD furnace or steel ladle obtained in the step (2) for multiple times, blowing inert gas into the AOD furnace or steel ladle, stirring, adding the reducing agent and the slagging agent, keeping the temperature of iron in the furnace to 1600-1650 ℃, discharging slag, taking a slag sample and/or an iron sample, analyzing the alkalinity of the slag sample and the iron content in the slag sample and/or the iron sample, and meeting the tapping requirement if the iron content in the furnace reaches more than 99% and the alkalinity is between 2 and 3; otherwise, continuously adding a reducing agent and a slag discharging agent for reduction and purification.
Before the hot iron oxide slag is added into the furnace, in order to prevent the bottom of the AOD furnace or the ladle from being washed, a slagging agent is added into the furnace in advance to carry out bottom padding. However, too much bedding should not be added, otherwise the temperature of the iron oxide hot slag is greatly reduced. In some embodiments, the amount of slag former added in step (1) is 0.8% -1.2% of the capacity of the AOD furnace or ladle bath. For example, the capacity of a melting bath of a certain AOD furnace is 100 tons, and 1 ton of slag former can be added in advance.
The iron oxide slag which can be added in the step (2) of the invention is not more than the holding capacity of the AOD furnace or the ladle molten pool. In some embodiments, the iron oxide slag of step (2) is iron oxide slag as an associated product of refining nickel matte or ferronickel. Directly collecting iron oxide slag discharged during refining high nickel matte or high nickel iron, and adding the iron oxide slag into the AOD furnace or the steel ladle; the temperature of the iron oxide slag is not lower than 1400 ℃ during the blending, and is preferably not lower than 1500 ℃. The invention directly collects and utilizes the iron oxide slag discharged when refining the high nickel iron, and the iron oxide slag is received by a metallurgical container and added into an AOD furnace or a steel ladle for reduction operation. If the slag yield of the upstream hot iron oxide slag cannot fully fill the AOD furnace or the ladle molten pool at one time, the hot iron oxide slag can be added in stages to be reduced and refined according to the method of the invention.
In some embodiments, the iron oxide slag comprises, by mass: siO2 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 (chromium) component 2 O 3 : preferably less than 1 percent, and in order to ensure that other trace elements of the pure iron do not exceed the standard, the lower the other trace elements are, the better the trace elements are.
For the AOD furnace, the step (2) can be performed by side gun side blowing of inert gas for stirring; for the ladle, the step (2) may be performed with stirring using bottom-blown inert gas of a bottom lance. The supply amount of the inert gas in the step (2) is 90-110m 3 Min; the supply amount of the inert gas in the step (3) is 90-110m 3 /min。
According to the amount of the added iron oxide slag, a proper reducing agent is prepared, and the AOD furnace side gun or the ladle bottom gun is used for supplying inert gas to fully reduce the iron oxide in the slag; by using the principle of reduction and heat release, the reducing agent is added in batches, so that the problem that the temperature in the furnace cannot be controlled due to rapid temperature rise caused by adding a large amount of reducing material at one time and the furnace lining and furnace bricks are seriously corroded due to overhigh temperature is avoided. In some embodiments, the mass ratio of the reducing agent and the slag former added for the first time in the step (3) is 1. 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 slagging agent into the AOD furnace or the ladle for multiple times, after adding the reducing agent and the slagging agent in the step (3), enabling the iron temperature in the furnace to reach 1600-1650 ℃, discharging slag, taking a slag sample and an iron sample, analyzing the alkalinity of the slag sample and the iron content in the slag sample and/or the iron sample, and if the iron content in the furnace reaches more than 99 percent and the alkalinity is between 2 and 3, achieving the tapping requirement; otherwise, the reducing agent and the slagging constituent are continuously added for reduction purification, and in order to better control the furnace temperature and achieve the reduction expectation as soon as possible, the method can be carried out according to the following steps in the preferred embodiment:
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, the reducing agent and the slag former are added again according to the mass ratio of 1:2.5-3.2, and 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 to 3.1 to 3.3, wherein the added reducing agent accounts for 75 to 85 percent of the mass of the reducing agent added for the first time;
when the alkalinity in the furnace is more than 3, simultaneously adding the reducing agent and the slagging constituent again according to the mass ratio of 1.3 to 2.6 to 2.8, wherein the mass of the added reducing agent is 1.2 to 1.4 times of that of the reducing agent added for the first time.
After the reducing material and the slag former are fed in batches, in small amount and for many times, and the inert gas is fully stirred, a slag sample or an iron sample is taken to analyze and confirm that the content of iron oxide in slag or the content of iron in molten iron and the alkalinity in slag can carry out slag discharge operation, the waste slag is discharged, and the molten iron is left in the furnace. Repeating the above operations, adding the hot iron oxide slag for the second time, adding the reducing agent into nitrogen, stirring and fully reducing to enable the temperature of iron in the furnace to reach about 1600-1650 ℃, discharging slag, taking a slag sample and/or an iron sample, and testing and analyzing to confirm whether the content of iron in the furnace reaches more than 99 percent so as to meet the tapping requirement. By adopting the reduction method, the reducing agent with the weight of about 20 percent of the original iron oxide hot slag is generally used for fully reducing the iron oxide content of 60 to 70 percent of the original iron oxide hot slag to meet the tapping requirement.
The invention mixes the reducing agent and the slagging constituent by batches: adding a reducing agent and a slagging agent into an AOD furnace or a steel ladle added with hot iron oxide slag for multiple times, blowing inert gas into the AOD furnace or the steel ladle, stirring, adding the reducing agent and the slagging agent, then adjusting the usage amount of ferrosilicon in the reducing agent according to the initial temperature of the hot iron oxide slag to ensure that the temperature of iron in the furnace reaches 1600-1650 ℃, discharging slag, taking a slag sample and/or an iron sample, analyzing the alkalinity of the slag sample and the iron content in the slag sample and/or the iron sample, and meeting the tapping requirement if the iron content in the furnace reaches more than 99% and the alkalinity is between 2 and 3; otherwise, continuously adding the reducing agent and the slagging constituent for reduction and purification. The iron content in the furnace can be indirectly judged according to the iron oxide content in the slag sample or directly judged 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 iron oxide on the one hand, and on the other hand, the ferrosilicon releases heat violently in the reduction process, and the reaction temperature in the reduction process is favorably maintained. The ratio of the ferrosilicon to the coke can be determined according to the temperature of the hot slag of the iron oxide, and generally, if the temperature of the hot slag of the iron oxide is higher than or equal to 1500 ℃, the mass ratio of the ferrosilicon to the mixed reducing agent is 1/4; if the temperature of the hot slag of iron oxide is lower than 1500 ℃, the ratio of ferrosilicon to the mixed reducing agent can be increased appropriately, for example, to 1/3.5 to 1/3.9, or adjusted according to the initial temperature of the hot slag of iron oxide.
AOD furnaces are commonly used for refining stainless steel by blowing O into the steel during smelting 2 Ar or N 2 And (3) decarbonizing the molten steel by using mixed gas, simultaneously adding a reducing agent, a desulfurizing agent, an iron alloy or a coolant and the like into a feeding system to adjust the components and the temperature of the molten steel, smelting qualified stainless steel, discharging the molten steel into a steel ladle, and refining the qualified stainless steel in the steel ladle to provide finished molten steel of a continuous casting machine. The AOD furnace and the steel ladle are mature operating systems, and have the advantages of simple equipment, convenient operation, strong adaptability, investment saving, low production cost and the like, and both the AOD furnace and the steel ladle can provide strong stirring force of Ar gas and N2 gas, so that the AOD furnace and the steel ladle can be used as the equipment for reducing and refining pure iron by hot iron oxide slag.
The AOD furnace is generally used for injecting blast furnace molten iron and alloy melted on an intermediate frequency furnace into the AOD furnace through a steel ladle, oxygen, ar or nitrogen mixed gas is blown in during smelting to decarbonize molten steel, and meanwhile, a reducing agent, a desulfurizing agent, ferroalloy or a coolant and the like are added into a feeding system to adjust the components and the temperature of the molten steel, so that qualified stainless steel is smelted for a continuous casting machine. The method firstly reduces and refines pure iron by using the AOD furnace in the iron oxide hot slag associated with the ferronickel smelting, thereby changing waste into valuable.
Because other trace elements are added into the iron oxide slag, the process divides the product into 3 types:
(1) the content of iron reaches 99 percent, other trace elements exceed the requirements of raw material pure iron and industrial pure iron and are classified into inferior pure iron, and the inferior pure iron can be used for smelting stainless steel to adjust components after being cast iron;
(2) the iron content reaches more than 99.5 percent, and other trace elements meet the requirements of raw material pure iron, so that the method is divided into the alloy smelting and stainless steel smelting in the application field of raw material pure iron, and is mainly used for producing products such as neodymium iron boron, aluminum nickel cobalt, electrical alloy, high temperature and precision alloy and the like;
(3) the iron content reaches 99.6-99.8% and above, the total impurity content is less than 0.2%, and other elements meet the requirement of the internal control range of industrial pure iron, and the iron is divided into industrial pure iron which can be used for smelting important raw materials such as precision alloy, high-temperature alloy, ultra-low carbon stainless steel, electrothermal alloy and the like after being continuously cast into square billets.
The chemical reaction equation and process alkalinity control condition of the reduced iron of the process are as follows:
3C+Fe 2 O 3 = high temperature =2Fe +3CO ← ℃ +
Si +2FeO = high temperature = SiO 2 +2Fe
The process alkalinity is required to be controlled at ρ =2-3.
The following are examples:
example 1
Adding slag amount and components: in the embodiment, the slag is added once, the slag adding amount is 45T, and the component is 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 ℃.
1 ton of slag former is added before slag adding operation to fill the furnace bottom for spare reducing agents (ferrosilicon and coke) and slag former (lime) in an AOD high-level bunker;
is mixed inAfter the iron slag is oxidized, the AOD furnace side gun supplies inert gas (nitrogen gas), and the supply amount of the inert gas is 100m 3 Min, fully providing stirring force;
confirming that the reducing agent and the slagging agent are added from an overhead bin at the same time after the proper stirring strength is achieved, adding the reducing agent and the slagging agent according to the proportion of 1; 485kg of ferrosilicon, 2890kg of coke and 8930kg of lime are used in total, 4 batches of reducing agents and slagging agents are added, and then 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 percent. The specific reduction process data are shown in table 1:
TABLE 1
The slag discharge of the converter needs to be ensured to be clean, the iron can be discharged, the subsequent cast iron can be used, and the converter is used for fine adjustment of stainless steel smelting components.
Comparative example 1
Comparative example 1 is the same as the example, only the iron oxide slag is added once for reduction, but the iron content of the reduced product is less than 99 percent, and the component added with the 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 operation is the same as that of the example 1, the reduction time and the reduction temperature are basically the same, but the reducing agent is added in a small amount in the example, the ratio of the reducing agent added twice to the slag former is not as low as 1.5, and experiments show that the iron content of the corresponding reduction effect is not achieved, and the specific adding amount and the reduction condition are as shown in the following table 2:
TABLE 2
And (3) not knowing that iron oxide in the slag still has reduction allowance before the test, stirring for 5min after the last material is added, sampling and selecting tapping, wherein the final reduced 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 content of the reduced iron in the comparative example is less than 99 percent, and the possible reasons for the subsequent summary are that the total amount of the reducing agent is insufficient and the reducing agent is not sufficient and Fe in the slag is not sufficient 2 O 3 Reacting, wherein the content of Fe in the reduced molten iron does not reach saturation, and the ratio of the reducing agent to the slagging constituent is 1:2.36 is low and can not meet the requirements of target components, and is subsequently applied to stainless steel smelting fine adjustment components.
Example 2
Adding slag amount and components: the first stage iron oxide slag comprises the following components: siO2 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 percent; 40 tons of iron oxide slag are added in the first stage; since the slag yield of the upstream hot iron oxide slag cannot fill the AOD furnace molten pool at one time, the hot iron oxide slag is added in two stages in the embodiment. The second stage iron oxide slag comprises the following components: siO2 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 percent; in the second stage, 32 tons of iron oxide slag are added; the temperature of the iron oxide slag is 1500 ℃.
Reducing agents (ferrosilicon and coke) and slagging agents (lime) are put into a high-level bin of the AOD furnace in advance for standby, and 1 ton of the slagging agents are added before slag mixing operation to fill the furnace bottom;
after adding iron oxide slag, supplying inert gas (nitrogen) to the side gun of the AOD furnace, wherein the supply amount of the inert gas is 100m 3 Min, fully providing stirring force;
confirming that a reducing agent and a slagging agent are added from an overhead bunker at the same time after reaching a proper stirring strength, adding the reducing agent and the slagging agent according to the proportion of 1; the amounts added and the process iron oxide content are given in table 3 below.
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 the second reduction, and repeating the steps of adding the reducing agent and the slag forming agent; the last slag sample component of the first stage: siO2 2 ：27.05％，Al 2 O 3 ：1.78％，CaO：57.22％，MgO：6.46％，Fe 2 O 3 :6.10%, iron-like component: fe:97.46%, C:0.148%, P:0.004%, S:0.028 percent. At this time, the iron oxide in the slag is fully reduced and can be added into the second iron oxide slag for the second stage of reduction;
repeating the above operations to perform second stage reduction, wherein the slag sample components in the last time in the second stage are as follows: siO2:26.91%, al2O3:1.80%, caO:51.60%, mgO:2.76%, fe2O3:15.07%, iron sample of finished product: fe:99.76%, C:0.003%, P:0.004%, S:0.02%, si:0.01%, cr:0.1%, ni:0.05 percent;
the slag can be discharged after the components are qualified, the slag discharging operation needs to be clean without leaving slag, the slag is conveyed to a pig casting machine for casting, and the furnace can be used as raw material pure iron.
Comparative example 2
The comparison example is added with the iron oxide slag twice, because the iron oxide slag is added twice for the first time for testing, the iron content caused by the fact that the iron oxide slag components are not selected is not up to the standard in the early stage of testing, and other elements exceed the standard, and the specific components are the iron oxide slag components in the first stage: siO2 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 percent; the second stage iron oxide slag comprises the following components: siO2 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％；
Carrying out reduction operation according to the operation process requirements of the embodiment 2, adding the reducing agent and the slag former according to the ratio of 1.5-3.1, keeping the process alkalinity as rho =2-3, adding the materials in 4 batches in the reduction process, controlling the reduction time to be stirred for 4-6min by nitrogen, and showing the specific process indexes as the following table 4:
TABLE 4
Compared with the previous test, the case reduction process has no abnormity, and the finished product iron sample is as follows: 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, the Cr element component exceeds the standard, the possible reason is that the chromium sesquioxide is easy to reduce and cannot be removed, and the follow-up selection of the hot slag of the ferrous oxide needs to select the one with refined high-nickel iron as much as possibleThe early-stage slag is used as a raw material, the Cr element in the molten iron in the early-stage slag is oxidized to cause the content of chromium sesquioxide in the slag to be higher, so that the early-stage slag is not selected to be used for pure iron reduction, and the iron oxide slag in the following range is obtained to be suitable for reducing pure iron: siO2 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 proper; cr (chromium) component 2 O 3 : preferably less than 1%.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A method for extracting pure iron from iron oxide slag by using an AOD furnace or a ladle is characterized by comprising the following steps:
(1) Adding a slagging agent: adding a slag former into the bottom of the AOD furnace or the bottom of a steel ladle to ensure the alkalinity in the smelting process and avoid scouring a furnace lining when adding hot iron oxide slag;
(2) Adding hot iron oxide slag: adding hot iron oxide slag into the AOD furnace or the steel ladle added with the slagging agent at the bottom in the step (1); blowing inert gas into the AOD furnace or the ladle for stirring;
(3) Adding a reducing agent and a slagging agent in batches: adding a reducing agent and a slagging agent into the AOD furnace or steel ladle obtained in the step (2) for multiple times, blowing inert gas into the AOD furnace or steel ladle, stirring, adding the reducing agent and the slagging agent, keeping the temperature of iron in the furnace to 1600-1650 ℃, discharging slag, taking a slag sample and/or an iron sample, analyzing the alkalinity of the slag sample and the iron content in the slag sample and/or the iron sample, and if the iron content in the furnace reaches more than 99% and the alkalinity is between 2 and 3, achieving the tapping requirement; otherwise, continuously adding the reducing agent and the slagging constituent for reduction and purification.
2. The method of claim 1, wherein the amount of slag former added in step (1) is 0.8% to 1.2% of the AOD furnace or ladle volume.
3. The method of claim 1, wherein the hot iron oxide slag of step (2) is hot iron oxide slag that is an associated product of refining nickel matte or ferronickel.
4. The method according to claim 1, wherein in the step (2), the hot iron oxide slag discharged when refining high grade nickel matte or high grade nickel iron is directly collected and added into the AOD furnace or the ladle; the temperature of the iron oxide hot slag is not lower than 1400 ℃ during the adding.
5. The method of claim 3, wherein the iron oxide hot slag comprises, by mass: siO2 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％。
6. The method of claim 1, wherein for the AOD furnace, step (2) uses side lance side blowing inert gas for agitation; and (3) stirring the ladle by using bottom lance bottom blowing inert gas in the step (2).
7. The method of claim 1, wherein the inert gas is supplied in an amount of 90 to 110m in step (2) 3 Min; the supply amount of the inert gas in the step (3) is 90-110m 3 /min。
8. The method according to claim 1, wherein the mass ratio of the reducing agent and the slag former added for the first time in the step (3) is 1.
9. The method of claim 1, wherein the reducing agent and the slag former are continuously added in the step (3) for reduction and purification, and the method comprises the following steps:
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, the reducing agent and the slag former are added again according to the mass ratio of 1:2.5-3.2, and 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 to 3.1 to 3.3, wherein the added reducing agent accounts for 75 to 85 percent of the mass of the reducing agent added for the first time;
when the alkalinity in the furnace is more than 3, simultaneously adding the reducing agent and the slagging constituent again according to the mass ratio of 1.3 to 2.6 to 2.8, wherein the mass of the added reducing agent is 1.2 to 1.4 times of that of the reducing agent added for the first time.
10. The method of claim 1, wherein the slagging agent is fluorite lime; the reducing agent is ferrosilicon and/or coke.
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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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