CN116855667A - Recycling method of solid waste generated in pretreatment of molten iron - Google Patents
Recycling method of solid waste generated in pretreatment of molten iron Download PDFInfo
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- CN116855667A CN116855667A CN202310879501.0A CN202310879501A CN116855667A CN 116855667 A CN116855667 A CN 116855667A CN 202310879501 A CN202310879501 A CN 202310879501A CN 116855667 A CN116855667 A CN 116855667A
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 66
- 238000000034 method Methods 0.000 title claims abstract description 46
- 229910052742 iron Inorganic materials 0.000 title claims abstract description 33
- 238000004064 recycling Methods 0.000 title claims abstract description 18
- 239000002910 solid waste Substances 0.000 title claims abstract description 16
- 239000002893 slag Substances 0.000 claims abstract description 109
- 238000006477 desulfuration reaction Methods 0.000 claims abstract description 44
- 230000023556 desulfurization Effects 0.000 claims abstract description 44
- 238000003723 Smelting Methods 0.000 claims abstract description 40
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 31
- 239000011593 sulfur Substances 0.000 claims abstract description 30
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims abstract description 29
- 238000007670 refining Methods 0.000 claims abstract description 18
- 238000005275 alloying Methods 0.000 claims abstract description 16
- 229910000915 Free machining steel Inorganic materials 0.000 claims abstract description 9
- 229910000831 Steel Inorganic materials 0.000 claims description 91
- 239000010959 steel Substances 0.000 claims description 91
- 238000010079 rubber tapping Methods 0.000 claims description 27
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 21
- 229910052760 oxygen Inorganic materials 0.000 claims description 21
- 239000001301 oxygen Substances 0.000 claims description 21
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 14
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 14
- 239000004571 lime Substances 0.000 claims description 14
- 229910052799 carbon Inorganic materials 0.000 claims description 13
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 10
- 238000007599 discharging Methods 0.000 claims description 10
- 229910000514 dolomite Inorganic materials 0.000 claims description 10
- 239000010459 dolomite Substances 0.000 claims description 10
- 239000005997 Calcium carbide Substances 0.000 claims description 7
- 229910000616 Ferromanganese Inorganic materials 0.000 claims description 7
- 229910000720 Silicomanganese Inorganic materials 0.000 claims description 7
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 7
- DALUDRGQOYMVLD-UHFFFAOYSA-N iron manganese Chemical compound [Mn].[Fe] DALUDRGQOYMVLD-UHFFFAOYSA-N 0.000 claims description 7
- 229910052710 silicon Inorganic materials 0.000 claims description 7
- 239000010703 silicon Substances 0.000 claims description 7
- CLZWAWBPWVRRGI-UHFFFAOYSA-N tert-butyl 2-[2-[2-[2-[bis[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]amino]-5-bromophenoxy]ethoxy]-4-methyl-n-[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]anilino]acetate Chemical compound CC1=CC=C(N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)C(OCCOC=2C(=CC=C(Br)C=2)N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)=C1 CLZWAWBPWVRRGI-UHFFFAOYSA-N 0.000 claims description 7
- 229910045601 alloy Inorganic materials 0.000 claims description 6
- 239000000956 alloy Substances 0.000 claims description 6
- 238000005266 casting Methods 0.000 claims description 6
- 238000009749 continuous casting Methods 0.000 claims description 6
- 238000005070 sampling Methods 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 5
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 4
- 229910004261 CaF 2 Inorganic materials 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- MBMLMWLHJBBADN-UHFFFAOYSA-N Ferrous sulfide Chemical compound [Fe]=S MBMLMWLHJBBADN-UHFFFAOYSA-N 0.000 claims description 3
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims 3
- CADICXFYUNYKGD-UHFFFAOYSA-N sulfanylidenemanganese Chemical compound [Mn]=S CADICXFYUNYKGD-UHFFFAOYSA-N 0.000 abstract description 10
- 238000009628 steelmaking Methods 0.000 abstract description 9
- 239000002699 waste material Substances 0.000 abstract description 6
- 230000000052 comparative effect Effects 0.000 description 7
- 239000003795 chemical substances by application Substances 0.000 description 5
- 238000011084 recovery Methods 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 230000003009 desulfurizing effect Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 229910001341 Crude steel Inorganic materials 0.000 description 2
- 230000003111 delayed effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000007885 magnetic separation Methods 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000013589 supplement Substances 0.000 description 2
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000010881 fly ash Substances 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0068—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 by introducing material into a current of streaming metal
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0075—Treating in a ladle furnace, e.g. up-/reheating of molten steel within the ladle
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
- C22C33/06—Making ferrous alloys by melting using master alloys
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
-
- 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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- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Multimedia (AREA)
- Treatment Of Steel In Its Molten State (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
Abstract
The invention belongs to the technical field of steelmaking, and particularly relates to a recycling method of solid waste generated in molten iron pretreatment, in particular to a method for applying KR desulfurization slag generated in KR molten iron pretreatment to smelting of sulfur-containing free-cutting steel. According to the invention, after normal smelting deoxidation and alloying of the converter, KR desulfurization slag is added during LF refining, and the combined use of the KR desulfurization slag, a converter deoxidation product and a converter final slag is fully utilized, so that sulfur in the KR desulfurization slag is successfully recovered, the recycling of waste slag is realized, the consumption of steelmaking sulfur and iron is reduced, the smelting cost is reduced, the pollution and harm of the waste slag to the environment are reduced, and the spindle rate of manganese sulfide is improved. The method provided by the invention does not need to change the smelting process flow of the sulfur-containing free-cutting steel, is convenient for treating the desulfurization slag, and is convenient for popularization in the whole industry.
Description
Technical Field
The invention belongs to the technical field of steelmaking, in particular to the field of solid waste recovery steelmaking, and particularly relates to a recycling method of molten iron pretreatment solid waste.
Background
Steelmaking produces a large amount of solid waste including molten iron pretreatment slag, converter slag, LF refining slag, fly ash, etc., with KR desulfurization slag being one of the representative solid wastes. KR desulfurization is a process for pretreating molten iron outside a converter before converter steelmaking, has the characteristics of simple operation, low cost, high desulfurization efficiency and the like, and is widely adopted by domestic iron and steel enterprises. The desulfurizing agent used for KR desulfurization is lime-based, calcium carbide-based, soda-based, magnesium-based and the like, wherein the lime-based desulfurizing agent is easy to obtain and low in cost, and is the most common desulfurizing agent. The KR desulfurization slag is a byproduct generated by the desulfurization process, the yield of the KR desulfurization slag is about 7-9 kg/ton of steel, and about one third of the crude steel is calculated by using the KR desulfurization process molten iron pretreatment according to the annual crude steel yield of 10 hundred million tons in China, and the generated KR desulfurization slag exceeds 200 ten thousand tons/year.
At present, the main treatment mode of the KR desulfurization slag in China is to recycle iron in the slag by magnetic separation, the desulfurization slag is changed into solid waste to be accumulated and discarded, along with the continuous increase of the steel yield, the accumulation amount of the KR desulfurization slag is continuously increased, and the pollution and the harm of sulfur-containing substances to the environment are large, so that the KR desulfurization slag has become a serious environmental protection problem. How to recycle sulfur in KR desulfurization slag, realizes the recycling of waste slag, reduces smelting cost, reduces pollution and harm of waste slag to environment, promotes the green development of iron and steel enterprises, and becomes a problem to be solved by iron and steel enterprises. In the method for smelting sulfur-containing steel by using desulfurization slag, sulfur in the desulfurization slag can be replaced by S in an oxidation mode, and the S element can be stably introduced into molten steel by optimizing a smelting process. Based on the above, the desulfurization slag can be recycled. The desulfurization slag is added into a ladle in advance before converter tapping, and the converter smelting deoxidation and alloying are required to be carried out in a delayed mode, so that a certain influence is caused on the normal process flow of the converter smelting, and special deoxidizers similar to SiC are required to be used for ensuring the recovery efficiency of sulfur. CN202110201652.1 is a process method for producing high-sulfur steel by recycling slag, which adds KR desulphurized slag at the beginning of converter smelting tapping, thus the operation can affect normal smelting, such as converter smelting deoxidation and alloying are delayed, and the special steelmaking product of slag is recycled by blending with cord steel. Still, special raw materials and auxiliary materials such as a special deoxidizer, cord steel refining recycling slag and the like are required to be matched, which is not beneficial to popularization in the whole industry. And how the effect of recovery of KR desulfurization slag was brought to the spindle ratio of manganese sulfide was not studied.
Therefore, the invention aims to solve the technical problem of how to improve the recovery efficiency of sulfur in the desulfurization slag and the spindle rate of manganese sulfide without adding special slag, and does not cause any influence on the smelting process.
Disclosure of Invention
In order to solve the problems, the invention adds the desulphurized slag during LF refining after deoxidation and alloying of normal converter smelting, and utilizes converter final slag to effectively improve SiO in LF refined slag 2 The content of the sulfur in the desulfurized slag is improved, a special deoxidizer is not needed, the sulfur in the KR desulfurized slag is successfully recovered through the combined use of the KR desulfurized slag, the deoxidized product of the converter and the final slag of the converter, the recycling of the waste slag is realized, the consumption of steelmaking sulfur and iron is reduced, the smelting cost is reduced, the pollution and the harm of the waste slag to the environment are reduced, the spindle rate of the manganese sulfide is improved, and the industrial popularization is facilitated.
A recycling method of solid waste of molten iron pretreatment is characterized in that KR desulfurization slag is subjected to hot disintegrating, crushing, magnetic separation and drying to obtain residual tailings, and the residual tailings are recycled to smelting of sulfur-containing free-cutting steel, so that sulfur increase of molten steel is realized.
The method for smelting the sulfur-containing free-cutting steel of the present invention will be described in detail.
Step one: smelting in a converter: the converter furnace burden structure is 90% of molten iron and 10% of scrap steel, the charging amount is 120 tons, wherein the scrap steel is common social scrap steel, and no special requirement exists. The converter adopts lime and light burned dolomite to produce low-alkalinity slag, wherein the addition amount of slag-making lime is 18-20 kg/ton steel, the addition amount of light burned dolomite is 10-15 kg/ton steel, and the slag alkalinity is controlled to be 1.2-1.6. The smelting end temperature of the converter is controlled to 1600-1630 ℃ and the end carbon content is controlled to 0.05-0.08%.
Step two: tapping by a converter: deoxidizing and alloying in the tapping process, wherein the deoxidizing and alloying addition alloy comprises the following steps: silicomanganese (4.6-5.0 kg/ton steel), low-carbon ferromanganese (17.8-18.0 kg/ton steel), ferrophosphorus (1.50-1.52 kg/ton steel), and no ferrosulfur is needed to be added; manually discharging slag in the tapping process, wherein the slag discharging amount is 600 kg/furnace; the silicon content of the tapping end point is controlled to be less than or equal to 0.03 percent.
Step three: LF refining: after the molten steel reaches LF refining, the temperature is raised to a small extent (the temperature raising rate is less than or equal to 0.05 ℃/s and the temperature raising range is less than or equal to 30 ℃), slag charge is not supplemented, the treated KR desulfurization slag is firstly added to serve as slag charge and sulfur is added to the molten steel, and the using amount of the KR desulfurization slag is 100 kg/ton of steel. And then sampling and analyzing the active oxygen of the molten steel, controlling the active oxygen content of the free-cutting steel to be 30-40 ppm, and after the oxygen determination is completed, using calcium carbide to deoxidize the slag surface according to the oxygen content, and adjusting the active oxygen content to a required range. Before LF smelting is finished, adding ferrosulfur (5.0 kg/ton of steel), and then suspending into a continuous casting process for normal casting.
The KR desulfurization slag treated in the invention comprises the following components in percentage by weight: caO:52.5 to 61.8 percent of SiO 2 ：9.1～12.5％、CaS：4.4～5.6％、CaF 2 ：1.0～3.8％、Al 2 O 3 : less than or equal to 3.5 percent, mgO: less than or equal to 3.0 percent, less than or equal to 0.5 percent of water and the balance of impurities.
In the invention, sulfur in KR desulfurization slag is mainly in the form of CaS and needs to be chemically reacted in order to enter molten steelSulfur should be reduced. According to the chemical reaction mechanism, the chemical reaction needs to be promoted to be carried out in the opposite direction of the formation of CaS by KR desulfurization, and the SiO in the slag needs to be increased 2 The content of Si in molten steel is reduced, and the temperature of the molten steel is properly reduced, so that the reverse reaction efficiency is improved. The invention uses a large amount of silicomanganese to deoxidize molten steel, and uses the converter final slag to effectively improve SiO in LF refining slag 2 The content of silicon at the tapping end point of the converter is controlled, and the full progress of the reverse reaction is ensured.
Advantageous effects
The recycling method of molten iron pretreatment solid waste is applied to sulfur-containing free-cutting steel smelting, the desulfurization slag is added during LF refining, the recovery rate of S in the desulfurization slag is improved by utilizing the final slag of the converter, and the sulfur in the KR desulfurization slag is successfully recycled by fully utilizing the combination of KR desulfurization slag, converter deoxidization products and converter final slag, so that the recycling of the slag is realized, the consumption of steelmaking sulfur iron is reduced, the smelting process is not influenced, the smelting cost is reduced, the pollution and harm of the slag to the environment are reduced, and the spindle rate of manganese sulfide is improved.
Detailed Description
Taking the example of producing sulfur-containing free-cutting steel Y1215 by the company, the smelting process flow of Y1215 is as follows: the method comprises the following specific chemical components in percentage by weight: less than or equal to 0.09%, si: less than or equal to 0.08 percent, mn:1.10 to 1.40 percent, P:0.04 to 0.09 percent, S:0.33 to 0.42 percent, less than or equal to 0.20 percent of Cr, ni and Cu, and the balance of iron and unavoidable impurities.
Example 1
1. Smelting in a converter: the converter furnace burden structure is 90% of molten iron and 10% of scrap steel, the charging amount is 120 tons, wherein the scrap steel is common social scrap steel, and no special requirement exists. The converter adopts lime and light burned dolomite to manufacture low-alkalinity slag, wherein the addition amount of slag-making lime is 18 kg/ton steel, the addition amount of light burned dolomite is 14 kg/ton steel, and the slag alkalinity is controlled at 1.3. The smelting end temperature of the converter is controlled to 1612 ℃, and the end carbon content is controlled to be 0.06%.
2. Tapping by a converter: deoxidizing and alloying in the tapping process, wherein the deoxidizing and alloying addition alloy comprises the following steps: silicomanganese (4.8 kg/ton steel), low carbon ferromanganese (17.9 kg/ton steel), ferrophosphorus (1.5 kg/ton steel), without adding ferrosulfur; manually discharging slag in the tapping process, wherein the slag discharging amount is 600 kg/furnace; the silicon content of the tapping end point is controlled to be 0.02 percent.
3. LF refining: after the molten steel reaches LF refining, the temperature is raised to a small extent (the temperature raising rate is less than or equal to 0.05 ℃/s and the temperature raising range is less than or equal to 30 ℃), slag charge is not supplemented, the treated KR desulfurization slag is firstly added to serve as slag charge and sulfur is added to the molten steel, and the using amount of the KR desulfurization slag is 100 kg/ton of steel. The KR desulfurization slag comprises the following components in percentage by weight: caO: 52.5-61.8%, siO2: 9.1-12.5%, caS:4.4 to 5.6 percent of CaF 2 ：1.0～3.8％、Al 2 O 3 : less than or equal to 3.5 percent, mgO: less than or equal to 3.0 percent, less than or equal to 0.5 percent of water and the balance of impurities. And then sampling and analyzing the active oxygen of the molten steel, and after the oxygen determination is completed, carrying out slag surface deoxidation by using calcium carbide, and adjusting the active oxygen content to 35ppm. Before LF smelting is finished, adding ferrosulfur (5.0 kg/ton of steel), and then suspending into a continuous casting process for normal casting.
Example 2
1. Smelting in a converter: the converter furnace burden structure is 90% of molten iron and 10% of scrap steel, the charging amount is 120 tons, wherein the scrap steel is common social scrap steel, and no special requirement exists. The converter adopts lime and light burned dolomite to manufacture low-alkalinity slag, wherein the addition amount of slag-making lime is 20 kg/ton steel, the addition amount of light burned dolomite is 15 kg/ton steel, and the slag alkalinity is controlled at 1.5. The smelting end temperature of the converter is controlled to be 1622 ℃, and the end carbon content is controlled to be 0.07%.
2. Tapping by a converter: deoxidizing and alloying in the tapping process, wherein the deoxidizing and alloying addition alloy comprises the following steps: silicomanganese (5.0 kg/ton steel), low carbon ferromanganese (17.8 kg/ton steel), ferrophosphorus (1.51 kg/ton steel), without adding ferrosulfur; manually discharging slag in the tapping process, wherein the slag discharging amount is 600 kg/furnace; the silicon content of the tapping end point is controlled to be 0.01 percent.
3. LF refining: after the molten steel reaches LF refining, the temperature is raised to a small extent (the temperature raising rate is less than or equal to 0.05 ℃/s and the temperature raising range is less than or equal to 30 ℃), slag charge is not supplemented, the treated KR desulfurization slag is firstly added to serve as slag charge and sulfur is added to the molten steel, and the using amount of the KR desulfurization slag is 100 kg/ton of steel. The KR desulfurization slag comprises the following components in percentage by weight: caO:52.5 to 61.8 percent of SiO 2 ：9.1～12.5％、CaS：4.4～5.6％、CaF 2 ：1.0～3.8％、Al 2 O 3 : less than or equal to 3.5 percent, mgO: less than or equal to 3.0 percent, less than or equal to 0.5 percent of water and the balance of impurities. And then sampling and analyzing the active oxygen of the molten steel, and after the oxygen determination is completed, carrying out slag surface deoxidation by using calcium carbide, and adjusting the active oxygen content to 37ppm. Before LF smelting is finished, adding ferrosulfur (5.0 kg/ton of steel), and then suspending into a continuous casting process for normal casting.
Comparative example 1
Smelting by adopting a conventional process:
1. smelting in a converter: the converter furnace burden structure is 90% of molten iron and 10% of scrap steel, the charging amount is 120 tons, wherein the scrap steel is common social scrap steel, and no special requirement exists. The converter adopts lime and light burned dolomite to produce low-alkalinity slag, wherein the addition amount of slag-making lime is 35 kg/ton steel, and the alkalinity of slag is controlled at 2.0. The smelting end temperature of the converter is controlled to be 1640 ℃, the end carbon content is controlled to be 0.04%, and the end silicon content is controlled to be 0.05%.
2. Tapping by a converter: deoxidizing and alloying in the tapping process, wherein the deoxidizing and alloying addition alloy comprises the following steps: low aluminum ferroaluminum (1.75 kg/ton steel), low carbon ferromanganese (21.7 kg/ton steel), ferrophosphorus (1.5 kg/ton steel), and ferrosulfur (10.2 kg/ton steel).
3. LF refining: after the molten steel reaches LF refining, the temperature is quickly raised (the temperature raising rate is more than or equal to 0.10 ℃/s and the temperature raising range is more than or equal to 50 ℃), a small amount of slag melting agent is added to supplement slag, then sampling is carried out to analyze the active oxygen of the molten steel, calcium carbide is used for carrying out slag surface deoxidation after the oxygen determination is completed, the active oxygen content is adjusted to 36ppm, and then the molten steel is hung into a continuous casting process for normal casting.
Comparative example 2
1. Smelting in a converter: the converter furnace burden structure is 90% of molten iron and 10% of scrap steel, the charging amount is 120 tons, wherein the scrap steel is common social scrap steel, and no special requirement exists. The converter adopts lime and light burned dolomite to produce low-alkalinity slag, wherein the addition amount of slag-making lime is 35 kg/ton steel, and the alkalinity of slag is controlled at 2.0. The smelting end temperature of the converter is controlled to be 1640 ℃, the end carbon content is controlled to be 0.04%, and the end silicon content is controlled to be 0.04%.
2. Tapping by a converter: deoxidizing and alloying in the tapping process, wherein the deoxidizing and alloying addition alloy comprises the following steps: silicomanganese (4.9 kg/ton steel), low carbon ferromanganese (17.7 kg/ton steel), ferrophosphorus (1.51 kg/ton steel), ferrosulfur (10.1 kg/ton steel); and during tapping, manual slag discharging is carried out, and the slag discharging amount is 600 kg/furnace.
3. LF refining: after the molten steel reaches LF refining, the temperature is quickly raised (the temperature raising rate is more than or equal to 0.10 ℃/s and the temperature raising amplitude is more than or equal to 50 ℃), a small amount of slag melting agent is added to supplement slag, then sampling is carried out to analyze the active oxygen of the molten steel, calcium carbide is used for carrying out slag surface deoxidation after the oxygen determination is completed, the active oxygen content is adjusted to 39ppm, and then the molten steel is hung into a continuous casting process for normal casting.
Comparative example 3
The procedure of example 1, step 2, in which "manual slag tapping during tapping in a converter was performed, was omitted, and 600 kg/furnace tapping was performed, and the other procedures were the same as in example 1. Under the influence of the influence, in order to ensure that the sulfur content meets the requirement, the quantity of added sulfur and iron is increased to 8.5 kg/ton of steel before LF smelting is finished.
The sulfur free-cutting steel Y1215 produced using the examples and comparative examples of the present invention had iron and sulfur consumption and manganese sulfide spindle ratios as shown in table 1 below:
TABLE 1
| Scheme numbering | Consumption of iron and sulfur (kg/ton steel) | Manganese sulfide spindle Rate (%) |
| Example 1 | 5.0 | 38 |
| Example 2 | 5.0 | 36 |
| Comparative example 1 | 10.2 | 16 |
| Comparative example 2 | 10.1 | 19 |
| Comparative example 3 | 8.5 | 21 |
Remarks: 1. the higher the spindle ratio of manganese sulfide in the steel, the better the turning workability of the steel.
2. The manganese sulfide was examined by an optical microscope, wherein the length/width of 5 or less was regarded as spindle-shaped manganese sulfide.
Claims (6)
1. A recycling method of solid waste of molten iron pretreatment is characterized by comprising the following steps: the method comprises the following specific steps:
step one: smelting in a converter: the converter furnace burden is molten iron and scrap steel, the converter adopts lime and light burned dolomite to produce low-alkalinity slag, the slag alkalinity is controlled to be 1.2-1.6, the smelting end temperature of the converter is controlled to be 1600-1630 ℃, and the end carbon content is controlled to be 0.05-0.08%;
step two: tapping by a converter: deoxidizing and alloying in the tapping process, wherein the deoxidizing and alloying addition alloy comprises the following steps: silicomanganese, low-carbon ferromanganese and ferrophosphorus are not needed to be added; manually discharging slag in the tapping process, wherein the silicon content of the tapping end point is controlled to be less than or equal to 0.03%;
step three: LF refining: after the molten steel reaches LF refining, the temperature is raised slightly, slag charge is not supplemented, KR desulfurization slag is added to serve as slag charge and to sulfur the molten steel, then sampling and analyzing active oxygen of the molten steel are carried out, after oxygen determination is completed, calcium carbide is used for slag surface deoxidation according to the oxygen content, the active oxygen content of free-cutting steel is controlled to be 30-40 ppm, ferrosulfur is added before LF smelting is finished, and then continuous casting is carried out in a hanging mode for normal casting.
2. The recycling method of solid waste of molten iron pretreatment according to claim 1, which is characterized in that: the furnace burden of the first step is 90% of molten iron and 10% of scrap steel, the lime addition amount is 18-20 kg/ton steel, and the light burned dolomite addition amount is 10-15 kg/ton steel.
3. The recycling method of solid waste of molten iron pretreatment according to claim 1, which is characterized in that: the adding amount of the silicomanganese in the second step is 4.6-5.0 kg/ton of steel, the adding amount of the low-carbon ferromanganese is 17.8-18.0 kg/ton of steel, the adding amount of the ferrophosphorus is 1.50-1.52 kg/ton of steel, and the slag discharging amount is 600 kg/furnace.
4. The recycling method of solid waste of molten iron pretreatment according to claim 1, which is characterized in that: the KR desulfurization slag comprises the following components in percentage by weight: caO:52.5 to 61.8 percent of SiO 2 ：9.1～12.5％、CaS：4.4～5.6％、CaF 2 ：1.0～3.8％、Al 2 O 3 : less than or equal to 3.5 percent, mgO: less than or equal to 3.0 percent, less than or equal to 0.5 percent of water and the balance of impurities.
5. The recycling method of solid waste of molten iron pretreatment according to claim 1, which is characterized in that: the third small-amplitude heating means that the heating rate is less than or equal to 0.05 ℃/s and the heating amplitude is less than or equal to 30 ℃.
6. The recycling method of solid waste of molten iron pretreatment according to claim 1, which is characterized in that: the consumption of KR desulfurization slag is 100 kg/ton of steel; and adding sulfur iron before LF smelting is finished, wherein the dosage of the sulfur iron is 5.0 kg/ton of steel.
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