CN115232906A - Preparation method of low-phosphorus high-purity pig iron - Google Patents
Preparation method of low-phosphorus high-purity pig iron Download PDFInfo
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- CN115232906A CN115232906A CN202110437841.9A CN202110437841A CN115232906A CN 115232906 A CN115232906 A CN 115232906A CN 202110437841 A CN202110437841 A CN 202110437841A CN 115232906 A CN115232906 A CN 115232906A
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- iron
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- 229910000805 Pig iron Inorganic materials 0.000 title claims abstract description 56
- 229910052698 phosphorus Inorganic materials 0.000 title claims abstract description 54
- 239000011574 phosphorus Substances 0.000 title claims abstract description 54
- 238000002360 preparation method Methods 0.000 title claims abstract description 17
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 280
- 229910052742 iron Inorganic materials 0.000 claims abstract description 138
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims abstract description 66
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims abstract description 45
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 39
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 36
- 239000000292 calcium oxide Substances 0.000 claims abstract description 36
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims abstract description 36
- 239000000203 mixture Substances 0.000 claims abstract description 29
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims abstract description 22
- 239000010436 fluorite Substances 0.000 claims abstract description 22
- 238000007664 blowing Methods 0.000 claims abstract description 19
- 238000005507 spraying Methods 0.000 claims abstract description 19
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 18
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 18
- 238000007670 refining Methods 0.000 claims abstract description 18
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 17
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 17
- 239000001301 oxygen Substances 0.000 claims abstract description 17
- 238000005266 casting Methods 0.000 claims abstract description 15
- 238000000465 moulding Methods 0.000 claims abstract description 8
- QVQLCTNNEUAWMS-UHFFFAOYSA-N barium oxide Chemical compound [Ba]=O QVQLCTNNEUAWMS-UHFFFAOYSA-N 0.000 claims description 30
- 229960005191 ferric oxide Drugs 0.000 claims description 17
- 238000000034 method Methods 0.000 claims description 17
- 238000006477 desulfuration reaction Methods 0.000 claims description 16
- 230000023556 desulfurization Effects 0.000 claims description 16
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 claims description 14
- 239000003610 charcoal Substances 0.000 claims description 13
- 239000002006 petroleum coke Substances 0.000 claims description 13
- 239000000843 powder Substances 0.000 claims description 13
- 238000001354 calcination Methods 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 claims description 3
- 238000009355 double cropping Methods 0.000 claims 1
- 230000000630 rising effect Effects 0.000 claims 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 abstract description 35
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 abstract description 25
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 abstract description 21
- 239000010703 silicon Substances 0.000 abstract description 21
- 229910052710 silicon Inorganic materials 0.000 abstract description 21
- 229910052717 sulfur Inorganic materials 0.000 description 21
- 239000011593 sulfur Substances 0.000 description 21
- 230000000052 comparative effect Effects 0.000 description 17
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 12
- 229910052799 carbon Inorganic materials 0.000 description 12
- 230000000694 effects Effects 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 7
- 230000003647 oxidation Effects 0.000 description 5
- 238000007254 oxidation reaction Methods 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 3
- 229910001141 Ductile iron Inorganic materials 0.000 description 3
- 229910001882 dioxygen Inorganic materials 0.000 description 3
- 238000003306 harvesting Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- 229910001018 Cast iron Inorganic materials 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 2
- AYJRCSIUFZENHW-UHFFFAOYSA-L barium carbonate Chemical compound [Ba+2].[O-]C([O-])=O AYJRCSIUFZENHW-UHFFFAOYSA-L 0.000 description 2
- 229910001422 barium ion Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Chemical compound O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 235000010755 mineral Nutrition 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 239000013049 sediment Substances 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 240000007594 Oryza sativa Species 0.000 description 1
- 235000007164 Oryza sativa Nutrition 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 230000003009 desulfurizing effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000005496 eutectics Effects 0.000 description 1
- 235000000396 iron Nutrition 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 229910001392 phosphorus oxide Inorganic materials 0.000 description 1
- 229920002401 polyacrylamide Polymers 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 235000009566 rice Nutrition 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- VSAISIQCTGDGPU-UHFFFAOYSA-N tetraphosphorus hexaoxide Chemical compound O1P(O2)OP3OP1OP2O3 VSAISIQCTGDGPU-UHFFFAOYSA-N 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 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
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/02—Dephosphorising or desulfurising
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C1/00—Refining of pig-iron; Cast iron
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/02—Dephosphorising or desulfurising
- C21C1/025—Agents used for dephosphorising or desulfurising
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/04—Removing impurities other than carbon, phosphorus or sulfur
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0025—Adding carbon material
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Abstract
The preparation method comprises the following steps: (1) molten iron desulphurization: blowing active calcium oxide and oxygen into blast furnace molten iron; and (2) desiliconizing molten iron: blowing a mixture of ferrous oxide and fluorite into the desulfurized molten iron in the step (1); and (3) dephosphorization of molten iron: blowing a dephosphorization agent and a carburant into the molten iron subjected to desiliconization in the step (2), and spraying carbon dioxide; and (4) molten iron refining: carrying out deslagging treatment on the dephosphorized molten iron in the step (3), adding a carburant after deslagging, refining at 1500-1600 ℃ for 30-60min; (5) casting and forming: and casting and molding the refined molten iron to obtain the high-purity pig iron. By adopting the preparation method, the elemental sulfur, silicon and phosphorus in the molten iron can be effectively removed by adopting a reasonable sequence, so that the quality of the high-purity pig iron is improved.
Description
Technical Field
The application relates to the field of smelting processes, in particular to a preparation method of low-phosphorus high-purity pig iron.
Background
The high-purity pig iron generally refers to cast pig iron, and along with the development of economy and society, the requirements of castings required by equipment are higher and higher, the requirements of high quality are higher and higher, and the requirements of high-quality cast iron materials are continuously increased. Therefore, the demand for high purity pig iron for the production of superior quality castings is increasing. Phosphorus has a great influence on low-temperature toughness of cast iron, and generally exists in iron ore in the form of phosphorus oxide and phosphate, and is reduced into elemental phosphorus entering pig iron in the blast furnace smelting process, and after molten iron with high phosphorus content is solidified, the phosphorus in the molten iron can be aggregated in a eutectic form at a grain boundary, so that the mechanical property of ductile iron is poor, and the ductility and toughness of ductile iron (particularly ductile iron with special requirements on performance under low-temperature conditions) are greatly influenced, so that the phosphorus is one of harmful elements strictly controlled in high-purity pig iron.
At present, in the production of high-purity pig iron, the content of harmful substance phosphorus is relatively high, and the performance of the high-purity pig iron is influenced. Therefore, it is urgently needed to develop a high-purity pig iron with low phosphorus.
Disclosure of Invention
In order to reduce the phosphorus content of high-purity pig iron, the application provides a method for preparing low-phosphorus high-purity pig iron.
The application provides a preparation method of low-phosphorus high-purity pig iron, which adopts the following technical scheme:
a preparation method of low-phosphorus high-purity pig iron comprises the following steps:
(1) Molten iron desulfurization: blowing active calcium oxide and oxygen into blast furnace molten iron at 1400-1500 ℃, wherein 0.5-1.5kg of the active calcium oxide is added into each ton of molten iron, and 2-6m of oxygen is added for carrying out harvesting;
(2) Desiliconizing molten iron: blowing a mixture of ferrous oxide and fluorite into the desulfurized molten iron in the step (1), wherein 1-3kg of the mixture of the ferrous oxide and the fluorite is added into each ton of molten iron;
(3) Dephosphorization of molten iron: spraying a mixture of a dephosphorizing agent and a carburant into the molten iron subjected to desiliconization in the step (2), and spraying carbon dioxide, wherein 10.5-17kg of the mixture of the dephosphorizing agent and the carburant is added into each ton of molten iron, and carbon dioxide is added for carrying out thin film plantation by 3-5 m;
(4) Refining molten iron: deslagging the dephosphorized molten iron obtained in the step (3), adding a carburant after deslagging, heating to 1500-1600 ℃ for refining, and refining for 30-60min, wherein 3-8kg of the carburant is added into each ton of molten iron;
(5) Casting and molding: and casting and molding the refined molten iron to obtain the high-purity pig iron.
By adopting the technical scheme, the steps of the method are adopted, firstly, the molten iron is subjected to desulfurization treatment and then desilicication treatment, the desulfurization rate of the molten iron can be improved and the sulfur in the molten iron can be reduced due to the existence of silicon in the desulfurization process, and the desulfurization efficiency can be further improved by adopting the activated calcium oxide and the oxygen for desulfurization, so that the subsequent dephosphorization is facilitated; carbon dioxide is introduced during dephosphorization, and the phosphorus can be favorably formed into precipitates, and other components introduced into the dephosphorization agent form precipitates, so that the impurity content is reduced, the phosphorus content in the high-purity pig iron is reduced, the recarburizing agent is introduced during dephosphorization, the recarburizing agent can provide carbon for molten iron, the activity coefficient of the phosphorus can be increased due to the increase of the carbon, and the dephosphorization is favorably carried out.
Optionally, the preparation method of the activated calcium oxide in the step (1) comprises the following steps: calcining calcium oxide at 1500-2000 deg.C for 60-120 min.
By adopting the technical scheme, the active calcium and the ferrous oxide are calcined, the content of the active calcium oxide in the calcium oxide can be increased, and a sulfur simple substance in the molten iron can be oxidized, so that the desulfurization is facilitated.
Optionally, the blowing speed of the activated calcium oxide in the step (1) is 5-10kg/min, the flow rate of the sprayed oxygen is 10-20 m/min, the spraying pressure is 1-5MPa, and the temperature of the molten iron is controlled at 1350-1500 ℃.
By adopting the technical scheme, the active calcium oxide can be better contacted with the molten iron, the oxidation of sulfur in the molten iron is facilitated, and the injection of oxygen can further improve the oxidation of sulfur in the molten iron, so that the desulfurization rate of the molten iron is improved.
Optionally, the weight ratio of the ferrous oxide to the fluorite in the step (2) is (3-6): 1.
by adopting the technical scheme, the ferrous oxide and the fluorite are reasonable in proportion, the oxidation of silicon in the molten iron can be further improved, and the desilication rate of the molten iron is improved.
Optionally, in the step (2), the blowing speed of the mixture of the ferrous oxide and the fluorite is 15-20kg/min, and the temperature of the molten iron is controlled at 800-1000 ℃.
By adopting the technical scheme, the ferrous oxide and the fluorite can be fully contacted with the silicon in the molten iron, and the silicon in the molten iron can be oxidized by selecting the temperature of 800-1000 ℃, so that the silicon content in the molten iron is reduced.
Optionally, the dephosphorizing agent in the step (3) is a mixture of barium oxide and ferric oxide, wherein the weight ratio of the barium oxide to the ferric oxide is (2-6): 1.
Through adopting above-mentioned technical scheme, adopt barium oxide and ferric oxide as the dephosphorization agent, can oxidize the simple substance phosphorus in the molten iron, generate the sediment, reach the effect of dephosphorization, and barium ion in the barium oxide can also react with the carbon dioxide that lets in and generate barium carbonate sediment to reach and get rid of the purpose of introducing into impurity, and behind the ferric oxide phosphorus simple substance, it can also increase the iron content in the molten iron, thereby improve the purity of molten iron.
Optionally, the carburant in step (3) and step (4) is a mixture of graphitized petroleum coke and charcoal powder, and the weight ratio of the graphitized petroleum coke to the charcoal powder is (5-8): 1.
by adopting the technical scheme, the graphitized petroleum coke and the charcoal powder are used as the carburant, so that the carbon content in the molten iron can be increased, the carbon content of the carburant is higher, the harmful impurities are less, the dephosphorization rate of the molten iron can be further improved, and the performance of the prepared high-purity pig iron can be improved.
Optionally, the weight ratio of the dephosphorizing agent to the carburant in the step (3) is (10-20): 1.
by adopting the technical scheme, the dephosphorization agent and the carburant are reasonable in proportion, and the dephosphorization effect on molten iron can be improved.
Optionally, in the step (3), the blowing speed of the dephosphorization agent and the recarburization agent is 30-50kg/min, the flow rate of the carbon dioxide injection is 15-30 m/min, and the injection pressure is 0.5-3MPa.
By adopting the technical scheme, the dephosphorization agent and the recarburization agent can be fully mixed with the molten iron, so that the removal rate of phosphorus in the molten iron is improved, and the content of phosphorus in the molten iron is reduced.
Optionally, the temperature rise speed in the step (4) is 10-20 ℃/min.
By adopting the technical scheme, the temperature of the molten iron can be uniformly increased from inside to outside, so that the temperature inside and outside the molten iron is consistent, and the uneven heating inside and outside the molten iron can be prevented.
In summary, the present application has the following beneficial effects:
1. according to the method, the desulfurization treatment, the desilication treatment and the dephosphorization treatment are carried out firstly, so that sulfur and silicon in the molten iron can be fully removed, and phosphorus can be removed easily, and the phosphorus content in the finally prepared high-purity pig iron is up to below 0.010%, the sulfur content is below 0.019%, the silicon content is below 0.115%, and the carbon content is about 3.8%.
2. Because the calcium oxide and the ferrous oxide are calcined at high temperature, the content of active calcium oxide in the calcium oxide is improved, so that the oxidation performance of the calcium oxide can be improved, and the sulfur in the molten iron can be effectively removed.
3. As the barium oxide and the ferric oxide are adopted as the desulfurizing agent and the carbon dioxide is introduced, the reduction of phosphorus in the molten iron can be improved, and the introduced barium ions can be further removed, so that the purity of the prepared high-purity pig iron is improved.
Detailed Description
The present application will be described in further detail with reference to examples.
Raw materials
Calcium oxide: the manufacturer: the manufacturing model of the environmental protection material company of Luoyang ice Qian is as follows: BQ-106;
ferrous oxide: the manufacturer: tianjin cast letter metal materials Co., ltd, production model: 0058;
fluorite: the manufacturer: lingshou county flourishing mineral processing factory, production model: ys-58;
barium oxide: the manufacturer: beijing Rockwell technologies, inc., production model number: HK3218;
iron oxide: the manufacturer: the Tuomalin mineral products of the Shijiazhuang, inc., produces the model: sjz441;
graphitized petroleum coke: the manufacturer: nanyang jinping mining ltd, particle size: 1-3mm;
charcoal powder: the manufacturer: linzhang county antenna carbon industry limited company, fixing carbon amount: 90 to 94 percent.
Examples
Example 1
Preparation of activated calcium oxide: calcining 3kg of calcium oxide at 2000 ℃ for 60min to obtain active calcium oxide.
A preparation method of low-phosphorus high-purity pig iron comprises the following steps:
(1) Molten iron desulphurization: carrying out blowing on the prepared activated calcium oxide by 1.5kg at the speed of 5kg/min in each ton of blast furnace molten iron at the temperature of 1400 ℃, and carrying out thin film rice transformation by spraying oxygen by 6m at the pressure of 1MPa and the speed of 20 m/min;
(2) Desiliconizing molten iron: blowing 1kg of a mixture of ferrous oxide and fluorite into the molten iron subjected to desulfurization in the step (1) at a speed of 20kg/min, wherein the weight ratio of the ferrous oxide to the fluorite is 3;
(3) Dephosphorization of molten iron: blowing 17kg of a mixture of a dephosphorizing agent and a recarburizing agent into the molten iron subjected to desiliconization in the step (2) at a speed of 30kg/min, and spraying carbon dioxide at a flow rate of 30 m/min under the pressure of 0.5MPa for 3m year, wherein the weight ratio of the dephosphorizing agent to the recarburizing agent is 10;
(4) Refining molten iron: deslagging the dephosphorized molten iron in the step (3), adding 3kg of a recarburizer after deslagging, refining at 1500 ℃, and refining for 30min, wherein the recarburizer is a mixture of graphitized petroleum coke and charcoal powder with the weight ratio of 5;
(5) Casting and molding: and casting and molding the refined molten iron to obtain the high-purity pig iron.
Example 2
A preparation method of low-phosphorus high-purity pig iron comprises the following steps:
(1) Molten iron desulfurization: spraying the prepared activated calcium oxide at a speed of 8kg/min to each ton of blast furnace molten iron at 1450 ℃, and spraying oxygen at a pressure of 3MPa and a speed of 15 m/min for 4m harvesting;
(2) Desiliconizing molten iron: blowing 2kg of a mixture of ferrous oxide and fluorite into the molten iron desulfurized in the step (1) at a speed of 18kg/min, wherein the weight ratio of the ferrous oxide to the fluorite is 3;
(3) Dephosphorization of molten iron: spraying 13kg of a mixture of a dephosphorizing agent and a recarburizing agent into the molten iron subjected to desiliconization in the step (2) at a speed of 30kg/min, and spraying carbon dioxide at a flow rate of 20 m/min under a pressure of 2MPa for 4m year, wherein the weight ratio of the dephosphorizing agent to the recarburizing agent is 15;
(4) Refining molten iron: adding 3kg of nonionic polyacrylamide into the dephosphorized molten iron obtained in the step (3), stirring for 50min, performing deslagging treatment, adding 5kg of carburant after deslagging, refining at 1550 ℃ for 40min, wherein the carburant is a mixture of graphitized petroleum coke and charcoal powder in a weight ratio of 5;
(5) Casting and forming: and casting and molding the refined molten iron to obtain the high-purity pig iron.
Example 3
A preparation method of low-phosphorus high-purity pig iron comprises the following steps:
(1) Molten iron desulfurization: carrying out 2m high-speed transformation by blowing 0.5kg of the prepared active calcium oxide at a speed of 15kg/min in each ton of blast furnace molten iron at 1500 ℃, and carrying out 2m high-speed transformation by spraying oxygen at a pressure of 5MPa and a speed of 10 m/min;
(2) Desiliconizing molten iron: blowing 2kg of a mixture of ferrous oxide and fluorite into the molten iron desulfurized in the step (1) at a speed of 15kg/min, wherein the weight ratio of the ferrous oxide to the fluorite is 3;
(3) Dephosphorization of molten iron: blowing 15kg of a mixture of a dephosphorizing agent and a recarburizing agent into the molten iron subjected to desiliconization in the step (2) at a speed of 50kg/min, and spraying carbon dioxide at a flow rate of 15 m/min under the pressure of 3MPa for 5m for carrying out the production of manganese dioxide, wherein the weight ratio of the dephosphorizing agent to the recarburizing agent is 15;
(4) Refining molten iron: carrying out deslagging treatment on the dephosphorized molten iron in the step (3), adding 8kg of a recarburizer after deslagging, refining at 1600 ℃, and refining for 60min, wherein the recarburizer is a mixture of graphitized petroleum coke and charcoal powder with the weight ratio of 5;
(5) Casting and forming: and casting and molding the refined molten iron to obtain the high-purity pig iron.
Example 4
Differences from example 2: step (1) molten iron desulphurization: 0.5kg of active calcium oxide is added into each ton of molten iron.
Example 5
Differences from example 2: step (1) molten iron desulphurization: 1.5kg of active calcium oxide is added into each ton of molten iron.
Example 6
Differences from example 2: step (1) molten iron desulphurization: and 2m oxygen is added into each ton of molten iron for harvesting.
Example 7
Differences from example 2: step (1) molten iron desulphurization: and 6m for adding oxygen into each ton of molten iron.
Example 8
Differences from example 2: step (2) molten iron desiliconization: the weight ratio of ferrous oxide to fluorite added into each ton of molten iron is 5.
Example 9
Differences from example 2: step (2) molten iron desiliconization: the weight ratio of ferrous oxide to fluorite added into each ton of molten iron is 6.
Example 10
Differences from example 8: dephosphorization of molten iron in step (3): the dephosphorizing agent is a mixture of barium oxide and ferric oxide, and the weight ratio of the barium oxide to the ferric oxide is (2).
Example 11
Differences from example 8: dephosphorizing molten iron in step (3): the dephosphorization agent is a mixture of barium oxide and ferric oxide, and the weight ratio of the barium oxide to the ferric oxide is 4.
Example 12
Differences from example 8: and (3) the dephosphorizing agent in the molten iron dephosphorization in the step (3) is a mixture of barium oxide and ferric oxide, and the weight ratio of the barium oxide to the ferric oxide is 6.
Example 13
Differences from example 11: the recarburizing agent in the molten iron dephosphorization in the step (3) and the molten iron refining in the step (4) is a mixture of graphitized petroleum coke and charcoal powder with the weight ratio of 6.
Example 14
Differences from example 11: the recarburizer in the molten iron dephosphorization in the step (3) and the molten iron refining in the step (4) is a mixture of graphitized petroleum coke and charcoal powder with the weight ratio of 8.
Example 15
Differences from example 13: the active calcium oxide is: calcining calcium oxide at 2000 deg.C for 120min to obtain active calcium oxide.
Example 16
Differences from example 13: the active calcium oxide is: calcining calcium oxide at 2000 deg.C for 80min to obtain active calcium oxide.
Example 17
Differences from example 13: the active calcium oxide is: calcining calcium oxide at 1800 deg.C for 80min to obtain active calcium oxide.
Example 18
Differences from example 13: the active calcium oxide is: calcining at 1500 deg.C for 80min to obtain active calcium oxide.
Comparative example
Comparative example 1
Differences from example 2: step (1) molten iron desulphurization: oxygen was not introduced.
Comparative example 2
Differences from example 2: and (2) replacing active calcium oxide with calcium oxide in molten iron desulphurization in the step (1).
Comparative example 3
Differences from example 2: molten iron desiliconization treatment is not carried out.
Comparative example 4
Differences from example 2: dephosphorization of molten iron in step (3): no carburant was added.
Comparative example 5
Differences from example 2: dephosphorization of molten iron in step (3): no carbon dioxide was added.
Comparative example 6
Differences from example 2: dephosphorizing molten iron in step (3): no carburant and no carbon dioxide were added.
Performance test
The contents (wt.%) of carbon, silicon, sulfur and phosphorus in the molten irons of examples 1 to 18 and comparative examples 1 to 6 were measured, wherein the lower the contents of silicon, sulfur and phosphorus, the better the high purity pig iron prepared.
Detection method
The contents (wt.%) of carbon, silicon, sulfur and phosphorus in molten iron were determined according to the method for detecting "JB-T11994-2014 high purity pig iron for casting". The results are detailed in Table 1.
TABLE 1 detection results of the components in molten iron
| C/wt.％ | Si/wt.％ | S/wt.％ | P/wt.％ | |
| Example 1 | 3.825 | 0.113 | 0.018 | 0.009 |
| Example 2 | 3.837 | 0.112 | 0.016 | 0.007 |
| Example 3 | 3.816 | 0.115 | 0.019 | 0.010 |
| Example 4 | 3.828 | 0.114 | 0.018 | 0.009 |
| Example 5 | 3.832 | 0.113 | 0.018 | 0.009 |
| Example 6 | 3.826 | 0.115 | 0.017 | 0.010 |
| Example 7 | 3.829 | 0.113 | 0.019 | 0.008 |
| Example 8 | 3.841 | 0.110 | 0.015 | 0.006 |
| Example 9 | 3.836 | 0.112 | 0.018 | 0.007 |
| Example 10 | 3.839 | 0.110 | 0.015 | 0.006 |
| Example 11 | 3.845 | 0.109 | 0.013 | 0.005 |
| Example 12 | 3.842 | 0.110 | 0.014 | 0.006 |
| Example 13 | 3.851 | 0.107 | 0.012 | 0.004 |
| Example 24 | 3.848 | 0.109 | 0.014 | 0.006 |
| Example 15 | 3.850 | 0.110 | 0.013 | 0.007 |
| Example 16 | 3.854 | 0.108 | 0.011 | 0.005 |
| Example 17 | 3.851 | 0.106 | 0.010 | 0.003 |
| Example 18 | 3.853 | 0.109 | 0.012 | 0.006 |
| Comparative example 1 | 2.854 | 0.315 | 0.218 | 0.087 |
| Comparative example 2 | 2.763 | 0.452 | 0.326 | 0.093 |
| Comparative example 3 | 2.935 | 0.837 | 0.526 | 0.218 |
| Comparative example 4 | 2.553 | 0.115 | 0.018 | 0.132 |
| Comparative example 5 | 2.663 | 0.114 | 0.017 | 0.146 |
| Comparative example 6 | 2.546 | 0.118 | 0.019 | 0.193 |
It can be seen from the combination of examples 1-3 and table 1 that changing the additive amounts and process parameters of the substances for desulfurization, desilicication and dephosphorization during the preparation of high purity pig iron can affect the contents of carbon, silicon, sulfur and phosphorus in the molten iron finally prepared, whereas the content of harmful elements silicon, sulfur and phosphorus in the high purity pig iron prepared by the technical scheme of example 2 in the present application is low, so that the purity and quality of the prepared high purity pig iron can be improved.
In the present application, the content of harmful elements silicon, sulfur and phosphorus in the prepared high-purity pig iron is low by adopting the active calcium oxide added in the embodiment 2 of the present application, which is beneficial to improving the purity and quality of the high-purity pig iron.
It can be seen from the combination of the embodiment 2 and the embodiments 6 to 7 and the combination of table 1 that different oxygen gases introduced into molten iron desulphurization all affect the finally prepared high purity pig iron, because the introduced oxygen gas oxidizes the elemental sulfur in the molten iron, and too little oxygen gas can result in insufficient oxidation of the elemental sulfur in the molten iron, thereby affecting the subsequent desiliconization and dephosphorization, and too much oxygen gas can generate titanium oxide with the titanium in the molten iron, thereby increasing the slag viscosity, making the gas escape difficult, causing the molten iron to splash, affecting the preparation of the molten iron, and further affecting the proceeding of the molten iron desulphurization, desiliconization and dephosphorization. By adopting the technical scheme in the embodiment 2 of the application, the effect of removing sulfur, silicon and phosphorus can be achieved well.
It can be seen from the combination of example 2 and examples 8-9 and table 1 that different proportions of ferrous oxide and fluorite added in the desilication of the molten iron all affect the sulfur, silicon and phosphorus contents of the finally prepared high purity pig iron, because in the desilication of the molten iron, a part of the remaining sulfur which is not oxidized is oxidized, and the elemental sulfur in the molten iron is further removed. In the present application, the amounts of ferrous oxide and fluorite used in example 8 of the present application can be used to further reduce the sulfur, silicon and phosphorus content in the molten iron.
It can be seen from the combination of example 8 and examples 10-12 and table 1 that changing the ratio of barium oxide to ferric oxide in the dephosphorizing agent has an effect on the content of carbon, sulfur, silicon and phosphorus in the finally prepared high-purity pig iron. According to the embodiment of the application, the quality of the prepared high-purity pig iron can be further improved by adopting the dephosphorizing agent in the embodiment 11 of the application.
It can be seen from the combination of example 11 and examples 13-14 and table 1 that, changing different proportions of the graphitized petroleum coke and the charcoal powder as the carburant has an influence on the final dephosphorization effect, and the final dephosphorization effect is the best when the graphitized petroleum coke and the charcoal powder are used in the carburant of example 13.
In the present examples, the activated calcium oxide obtained in example 17 was used, which is advantageous in improving the quality of high-purity pig iron, as it can be seen from the combination of example 13 and examples 15 to 18 with Table 1 that the contents of carbon, sulfur, silicon and phosphorus in the high-purity pig iron finally obtained were also affected by changing the preparation method of activated calcium oxide.
It can be seen from the combination of example 2 and comparative examples 1-2 and table 1 that the absence of oxygen and the selection of calcium oxide during the desulfurization of molten iron not only affect the desulfurization effect, but also affect the subsequent desilication and dephosphorization, and thus affect the sulfur, silicon and phosphorus content of the prepared high-purity pig iron.
Combining example 2 and comparative example 3 with table 1, it can be seen that, without desiliconization, not only the silicon content but also the sulfur and phosphorus content of the high purity pig iron produced increased.
In the case of combining example 2 and comparative examples 4 to 6 with table 1, it can be seen that the phosphorus content of the finally obtained high purity pig iron is affected by adding no carburant and carbon dioxide during dephosphorization of molten iron, and the phosphorus content is significantly increased compared with the phosphorus content of the finally obtained high purity pig iron by adding the carburant and carbon dioxide, so that the dephosphorization of molten iron can be more facilitated under the condition of introducing carbon dioxide and adding the carburant in the present application.
The specific embodiments are only for explaining the present application and are not limiting to the present application, and those skilled in the art can make modifications to the embodiments without inventive contribution as required after reading the present specification, but all the embodiments are protected by patent law within the scope of the claims of the present application.
Claims (10)
1. A preparation method of low-phosphorus high-purity pig iron is characterized by comprising the following steps:
(1) Molten iron desulfurization: blowing active calcium oxide into blast furnace molten iron at 1400-1500 ℃, and spraying oxygen, wherein 0.5-1.5kg of the active calcium oxide is added into each ton of the molten iron, and oxygen is added for carrying out the double cropping by 2-6 m;
(2) Desiliconizing molten iron: blowing a mixture of ferrous oxide and fluorite into the desulfurized molten iron in the step (1), wherein 1-3kg of the mixture of ferrous oxide and fluorite is added into each ton of molten iron;
(3) Dephosphorization of molten iron: spraying a mixture of a dephosphorizing agent and a carburant into the molten iron subjected to desiliconization in the step (2), and spraying carbon dioxide, wherein 10.5-17kg of the mixture of the dephosphorizing agent and the carburant is added into each ton of molten iron, and carbon dioxide is added for 3-5m for carrying out the plantation;
(4) Refining molten iron: deslagging the dephosphorized molten iron obtained in the step (3), adding a carburant after deslagging, heating to 1500-1600 ℃ for refining, and refining for 30-60min, wherein 3-8kg of the carburant is added into each ton of molten iron;
(5) Casting and forming: and casting and molding the refined molten iron to obtain the high-purity pig iron.
2. The method for preparing low-phosphorus high-purity pig iron according to claim 1, characterized in that: the preparation method of the active calcium oxide in the step (1) comprises the following steps: calcining calcium oxide at 1500-2000 deg.C for 60-120 min.
3. The method for preparing low-phosphorus high-purity pig iron according to claim 1, characterized by comprising the following steps: the spraying speed of the activated calcium oxide in the step (1) is 5-10kg/min, the flow of the sprayed oxygen is 10-20m for carrying out the high-speed transportation and the spraying pressure is 1-5MPa.
4. The method for preparing low-phosphorus high-purity pig iron according to claim 1, characterized in that: the weight ratio of the ferrous oxide to the fluorite in the step (2) is (3-6): 1.
5. the method for preparing low-phosphorus high-purity pig iron according to claim 1, characterized by comprising the following steps: and (3) in the step (2), the blowing speed of the mixture of the ferrous oxide and the fluorite is 15-20kg/min.
6. The method for preparing low-phosphorus high-purity pig iron according to claim 1, characterized by comprising the following steps: the dephosphorizing agent in the step (3) is a mixture of barium oxide and ferric oxide, wherein the weight ratio of the barium oxide to the ferric oxide is (2-6) to 1.
7. The method for preparing low-phosphorus high-purity pig iron according to claim 1, characterized by comprising the following steps: the recarburizing agent in the step (3) and the step (4) is a mixture of graphitized petroleum coke and charcoal powder, and the weight ratio of the graphitized petroleum coke to the charcoal powder is (5-8): 1.
8. the method for preparing low-phosphorus high-purity pig iron according to claim 1, characterized in that: the weight ratio of the dephosphorizing agent to the carburant in the step (3) is (10-20): 1.
9. the method for preparing low-phosphorus high-purity pig iron according to claim 1, characterized in that: and (3) blowing the dephosphorizing agent and the carburant at a speed of 30-50kg/min, spraying carbon dioxide at a flow rate of 15-30m for carrying out high-speed transportation/min and spraying pressure of 0.5-3MPa.
10. The method for preparing low-phosphorus high-purity pig iron according to claim 1, characterized in that: the temperature rising speed in the step (4) is 10-20 ℃/min.
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