CN111748670A - Method for improving chromium ore reduction by bottom blowing oxygen-lime powder - Google Patents
Method for improving chromium ore reduction by bottom blowing oxygen-lime powder Download PDFInfo
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- CN111748670A CN111748670A CN202010529370.XA CN202010529370A CN111748670A CN 111748670 A CN111748670 A CN 111748670A CN 202010529370 A CN202010529370 A CN 202010529370A CN 111748670 A CN111748670 A CN 111748670A
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- 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
- C21C5/005—Manufacture of stainless steel
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C33/06—Making ferrous alloys by melting using master alloys
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Abstract
The invention provides a method for improving chromium ore reduction by bottom blowing oxygen-lime powder, belonging to the technical field of stainless steel smelting. In the stainless steel smelting process, oxygen is used as carrier gas, lime powder is blown into a steel-making molten pool from the bottom of a smelting furnace through a spray gun, the oxygen is directly and fully contacted with the steel-making molten pool, the utilization rate is high, the reaction effect is good, the specific surface area of the lime powder blown together is large, and the slagging speed is high. The oxygen flow and the lime powder injection speed are adjusted in real time in different smelting stages, the slag alkalinity can be flexibly controlled, the molten pool stirring is effectively improved, the melting and reduction processes of the chromium ore in the slag are accelerated, the metal yield and the lime utilization rate of the chromium ore are improved, the stainless steel smelting period is shortened, and the production cost is reduced.
Description
Technical Field
The invention mainly belongs to the technical field of stainless steel smelting, and particularly relates to a method for improving chromium ore reduction by bottom blowing oxygen-lime powder.
Background
The chromium ore is the main raw material for smelting stainless steel, and is composed of various spinel phases including some SiO2And phosphide and sulfide. The spinel phase mainly comprises iron chromium spinel (FeO. Cr)2O3) Magnesium chromium spinel (MgO. Cr)2O3) And magnesium aluminate spinel (MgO. Al)2O3) And the melting point of the chromium ore is very high, the chromium ore cannot be quickly melted in the smelting process, and most of the chromium ore is suspended in slag in a solid phase form, so that the reduction speed of the chromium ore is low, the stainless steel smelting period is long, and the metal loss rate is high.
The smelting reduction of chromium ore is divided into two stages: (1) melting the chromium ore in the slag; (2) the molten chromium ore undergoes a reduction reaction at the slag-gold interface. The two stages have different requirements on the basicity of the slag, the lower basicity of the slag is beneficial to the melting of chromium ore, and the higher basicity of the slag can improve Cr2O3The activity of (2) is favorable for the reduction of chromium ore. The traditional method for adding lime into stainless steel smelting is that lime is all put into a steel-making molten pool in a blocky form from a furnace mouth at one time at the stage of adding slag-making materials, so that early-stage slag alkalinity is too high, chromium ore is not easy to melt, the blocky lime is low in melting speed in the whole smelting process and cannot be completely melted, the utilization rate of the lime is reduced, and resource waste is caused.
In the stainless steel smelting process, bottom blowing is a small-flow inert gas in most of the time, so that the stirring of a molten pool is insufficient, and FeO in slag is high. The low stirring strength causes the decomposition of MgO and Al in the process of melting the chromium ore2O3The chromium ore can be covered with the protective layer to form a compact protective layer, which prevents the further melting of the chromium ore. The high FeO content can increase Cr2O3The reduction temperature of (2) is not favorable for the decarbonization and chromium retention reaction.
Disclosure of Invention
Aiming at the problems, the invention provides a method for improving chromium ore reduction by bottom blowing oxygen-lime powder, which takes oxygen as carrier gas in the stainless steel smelting process, and blows the lime powder into a steelmaking molten pool from the bottom of a stainless steel smelting furnace through a spray gun, the oxygen is directly and fully contacted with the steelmaking molten pool, the utilization rate is high, the reaction effect is good, the specific surface area of the lime powder blown together is large, and the slagging speed is high. The oxygen flow and the lime powder injection speed are adjusted in real time in different smelting stages, the slag alkalinity can be flexibly controlled, the molten pool stirring is effectively improved, the melting and reduction processes of the chromium ore in the slag are accelerated, the metal yield and the lime utilization rate of the chromium ore are improved, the stainless steel smelting period is shortened, and the production cost is reduced.
The invention is realized by the following technical scheme:
a method for improving chromium ore reduction by bottom blowing oxygen and lime powder is characterized in that oxygen is used as carrier gas in a stainless steel smelting process, lime powder is blown into a steel-making molten pool from the bottom of a stainless steel smelting furnace through a spray gun, and oxygen flow and lime powder blowing speed in different smelting stages are adjusted in real time, so that the aim of quickly, continuously and efficiently reducing chromium ore is fulfilled. In the chromium ore melting period, spraying oxygen with a larger flow and lime powder with a smaller spraying speed into a molten pool of a stainless steel smelting furnace, controlling the alkalinity of lower slag, ensuring the rapid temperature rise of the molten pool, and accelerating the melting of chromium ore; in the initial reduction period, spraying oxygen with larger flow and lime powder with larger spraying speed into a molten pool of the stainless steel smelting furnace, properly increasing the alkalinity of the slag and promoting the reduction reaction of the chromium ore; in the continuous reduction period, spraying oxygen with a small flow and lime powder with a small spraying speed into a molten pool of the stainless steel smelting furnace, stabilizing the alkalinity of the slag and ensuring that chromium ore is continuously reduced; and in the deep reduction period, stopping spraying oxygen and lime powder into the molten pool of the stainless steel smelting furnace, spraying argon with larger flow, strengthening the stirring of the molten pool, and further promoting the deep reduction of the chromium ore.
Further, the specific parameters of the oxygen flow and the lime powder injection rate in different periods of stainless steel smelting are as follows:
the melting period of the chromium ore: controlling the oxygen flow to be 1000-3000 Nm3The lime powder injection rate is 10-100 kg/min, oxygen with larger flow can promote silicon and manganese elements to carry out oxidation reaction and release heat, the temperature rise of a molten pool of the stainless steel smelting furnace is accelerated, the stirring of the molten pool is promoted, and meanwhile, the lime powder with smaller injection rate can ensure that the alkalinity of the slag rises slowly and is maintained at a lower level in the beginning smelting period, so that chromium ore can be rapidly melted in the slag layer;
initial reduction period: controlling the oxygen flow to be 1000-3000 Nm3The lime powder injection rate is 100-300 kg/min, the oxygen with larger flow can promote the carbon element to carry out oxidation reaction and release heat, and continuously supplement heat for a molten pool, and meanwhile, the lime powder with larger injection rate can quickly increase the alkalinity of the slag to meet the alkalinity requirement suitable for chromium ore reduction;
and (3) a continuous reduction period: controlling the oxygen flow to be 500-1500 Nm3The lime powder injection rate is 10-100 kg/min, the small oxygen flow can reduce the oxidation loss of chromium in molten steel, the oxidation reaction of carbon is ensured to be continuously carried out, the molten pool is sufficiently stirred, the FeO content in slag is not too high, and meanwhile, the lime powder with the small injection rate can be continuously dissolved with chromium ore to generate SiO2Reacting, namely maintaining the alkalinity of the slag in a stable range, and ensuring the continuous reduction of the chromium ore;
deep reduction stage: stopping blowing in oxygen and lime powder, switching the oxygen into argon, and controlling the flow of the argon to be 1000-3000 Nm3And/h, the argon with larger flow reduces the CO partial pressure in the furnace, promotes the decarbonization and chromium protection reaction to occur in the positive direction, and further reduces the chromium ore.
Further, the spray gun is installed in stainless steel smelting furnace stove bottom refractory material, guarantees that the spray gun uses safely, according to the difference of stainless steel smelting furnace capacity and specification, the quantity of spray gun is 1 ~ 6.
Further, the smelting raw materials for stainless steel smelting are molten iron, chromium ore, ferrochrome and other chromium-containing metal materials, and the chromium ore comprises chromium ore, pre-reduced chromium ore and chromium ore powder.
Further, the stainless steel smelting adopts an AOD furnace, a K-OBM-S furnace, a GOR furnace, a TSR furnace or a traditional top-bottom combined blown converter, and the capacity of the stainless steel smelting furnace is 50-300 t.
Further, the particle size of the lime powder is 50-300 meshes.
The invention has the beneficial technical effects that:
in the invention, oxygen is taken as carrier gas in the stainless steel smelting process, lime powder is blown into a steel-making molten pool from the bottom of a smelting furnace through a spray gun, the oxygen flow and the lime powder blowing speed in different smelting stages are adjusted in real time, strong molten pool stirring is provided in the whole smelting process, lower slag alkalinity is controlled in the initial smelting stage, higher slag alkalinity is controlled and stabilized in the chromium ore reduction stage, good thermodynamic and kinetic conditions are provided for the chromium ore smelting reduction smelting, the metal yield of chromium ore and the utilization rate of slagging lime are improved, the stainless steel smelting period is shortened, and the production cost is reduced.
Drawings
FIG. 1 is a schematic view of a stainless steel smelting furnace according to the present invention;
FIG. 2 is a diagram showing blowing parameters of the spray gun in example 1 of the present invention;
FIG. 3 shows blowing parameters of the lance in example 2 of the present invention.
The reference signs are: 1. the bottom blowing gas source 2, the gas flow controller 3, the powder spraying tank 4, the bottom blowing gas pipeline 5, the powder rate controller 6, the bottom blowing spray gun 7 and the stainless steel smelting furnace.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further 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.
On the contrary, the invention is intended to cover alternatives, modifications, equivalents and alternatives which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, certain specific details are set forth in order to provide a better understanding of the present invention. It will be apparent to one skilled in the art that the present invention may be practiced without these specific details.
Example 1
The invention is applied to smelting stainless steel in a 70t TSR furnace, and the smelting raw materials are molten iron, chromium ore and ferrochrome. 2 bottom blowing spray guns are installed and symmetrically distributed on the central line of a trunnion at the bottom of the furnace, the carrier gas for conveying lime powder by the spray guns is oxygen, and the flow of a single gun is 600-1200 Nm3The argon is injected in the later stage of smelting, and the single-gun flow is 400-1200 Nm3And h, the single-gun blowing speed of the lime powder is 20-60 kg/min, and the granularity of the lime powder is 200 meshes. The blowing parameters of the lance are as shown in fig. 2.
The specific smelting process comprises the following steps:
(1) controlling the oxygen flow to be 1200Nm in the melting period of the chromium ore 0-20 min after the feeding3The lime powder blowing rate is 35 kg/min;
(2) 20-35 min, initial reduction period, and controlling the oxygen flow to be 1200Nm3The lime powder blowing rate is 60 kg/min;
(3) 35-58 min, continuous reduction period, and controlling oxygen flow at 600Nm3The lime powder blowing rate is 20 kg/min;
(4) 58-85 min, in the deep reduction period, stopping blowing oxygen and lime powder, and switching oxygen into argon at a flow rate of 1200Nm3/h；
(5) Tapping in 85min, and regulating the argon flow to 400Nm3And h, until tapping is finished.
By adopting the method, the yield of the chromium ore reaches more than 92%, and the production cost of each ton of steel is reduced by 20-30 yuan.
Example 2
The invention is applied to smelting stainless steel mother liquor in a 150t top-bottom combined blown converter, and the smelting raw materials are molten iron and chromium ore. 2 bottom blowing spray guns are installed and symmetrically distributed on the central line of a trunnion at the bottom of the furnace, the carrier gas for conveying lime powder by the spray guns is oxygen, and the flow of a single gun is 900-1500 Nm3The argon is injected in the later stage of smelting, and the single-gun flow is 500-1500 Nm3And h, the single-gun blowing speed of the lime powder is 60-110 kg/min, and the granularity of the lime powder is 200 meshes. The blowing parameters of the lance are as shown in fig. 3.
The specific smelting process comprises the following steps:
(1) controlling the oxygen flow to be 1500Nm in the melting period of the chromium ore 0-20 min after the feeding3The lime powder blowing rate is 60 kg/min;
(2) 20-35 min, initial reduction period, and oxygen flow rate controlled to 1500Nm3The lime powder blowing rate is 110 kg/min;
(3) 35-50 min, continuous reduction period, and controlling the oxygen flow to be 900Nm3The lime powder blowing rate is 80 kg/min;
(4) 50-55 min, in the deep reduction period, stopping blowing oxygen and lime powder, and switching oxygen into argon at a flow rate of 1500Nm3/h；
(5) Tapping for 55min, and regulating the argon flow to 500Nm3And h, until tapping is finished.
By adopting the method, the yield of the chromium ore reaches over 90 percent, and the production cost of each ton of steel is reduced by 15-25 yuan.
Claims (6)
1. A method for improving chromium ore reduction by bottom blowing oxygen-lime powder is characterized in that oxygen is used as carrier gas in a stainless steel smelting process, lime powder is blown into a steelmaking molten pool from the bottom of a stainless steel smelting furnace through a spray gun, and oxygen flow and lime powder blowing speed in different smelting stages are adjusted in real time, so that the aim of reducing chromium ore quickly, continuously and efficiently is fulfilled; in the chromium ore melting period, spraying oxygen with a larger flow and lime powder with a smaller spraying speed into a molten pool of a stainless steel smelting furnace, controlling the alkalinity of lower slag, ensuring the rapid temperature rise of the molten pool, and accelerating the melting of chromium ore; in the initial reduction period, spraying oxygen with larger flow and lime powder with larger spraying speed into a molten pool of the stainless steel smelting furnace, properly increasing the alkalinity of the slag and promoting the reduction reaction of the chromium ore; in the continuous reduction period, spraying oxygen with a small flow and lime powder with a small spraying speed into a molten pool of the stainless steel smelting furnace, stabilizing the alkalinity of the slag and ensuring that chromium ore is continuously reduced; and in the deep reduction period, stopping spraying oxygen and lime powder into the molten pool of the stainless steel smelting furnace, spraying argon with larger flow, strengthening the stirring of the molten pool, and further promoting the deep reduction of the chromium ore.
2. The method for improving chromium ore reduction by bottom blowing oxygen-lime powder according to claim 1, wherein specific parameters of oxygen flow and lime powder injection rate in different periods of stainless steel smelting are as follows:
the melting period of the chromium ore: controlling the oxygen flow to be 1000-3000 Nm3The lime powder injection rate is 10-100 kg/min, oxygen with larger flow can promote silicon and manganese elements to carry out oxidation reaction and release heat, the temperature rise of a molten pool of the stainless steel smelting furnace is accelerated, the stirring of the molten pool is promoted, and meanwhile, the lime powder with smaller injection rate can ensure that the alkalinity of the slag rises slowly and is maintained at a lower level in the beginning smelting period, so that chromium ore can be rapidly melted in the slag layer;
initial reduction period: controlling the oxygen flow to be 1000-3000 Nm3The lime powder injection rate is 100-300 kg/min, the oxygen with larger flow can promote the carbon element to carry out oxidation reaction and release heat, and continuously supplement heat for a molten pool, and meanwhile, the lime powder with larger injection rate can quickly increase the alkalinity of the slag to meet the alkalinity requirement suitable for chromium ore reduction;
and (3) a continuous reduction period: controlling the oxygen flow to be 500-1500 Nm3The lime powder injection rate is 10-100 kg/min, the small oxygen flow can reduce the oxidation loss of chromium in molten steel, the oxidation reaction of carbon is ensured to be continuously carried out, the molten pool is sufficiently stirred, the FeO content in slag is not too high, and meanwhile, the lime powder with the small injection rate can be continuously dissolved with chromium ore to generate SiO2Reacting to maintain the alkalinity of the slag in a stable range and ensure thatThe reduction of the chromium ore is continuously carried out;
deep reduction stage: stopping blowing in oxygen and lime powder, switching the oxygen into argon, and controlling the flow of the argon to be 1000-3000 Nm3And/h, the argon with larger flow reduces the CO partial pressure in the furnace, promotes the decarbonization and chromium protection reaction to occur in the positive direction, and further reduces the chromium ore.
3. The method for improving chromium ore reduction by bottom blowing oxygen-lime powder according to claim 1, wherein the spray guns are installed in the bottom refractory material of the stainless steel smelting furnace to ensure safe use of the spray guns, and the number of the spray guns is 1-6 according to different capacities and specifications of the stainless steel smelting furnace.
4. The method for improving the reduction of the chromium ore by bottom blowing the oxygen and the lime powder according to claim 1, wherein the smelting raw materials for stainless steel smelting are molten iron, chromium ore and ferrochrome and other chromium-containing metal materials, and the chromium ore comprises chromium ore, pre-reduced chromium ore and chromium ore powder.
5. The method for improving chromium ore reduction by bottom blowing oxygen-lime powder according to claim 1, wherein the stainless steel smelting adopts an AOD furnace, a K-OBM-S furnace, a GOR furnace, a TSR furnace or a traditional top-bottom combined blown converter, and the capacity of the stainless steel smelting furnace is 50-300 t.
6. The method for improving chromium ore reduction by bottom blowing oxygen-lime powder according to claims 1-2, wherein the particle size of the lime powder is 50-300 meshes.
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Cited By (2)
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| CN112853030A (en) * | 2021-01-04 | 2021-05-28 | 北京科技大学 | TSR furnace top bottom combined blowing CO2Method for smelting stainless steel |
| CN114807497A (en) * | 2022-03-28 | 2022-07-29 | 邯郸钢铁集团有限责任公司 | Method for smelting high-silicon molten iron by using bottom oxygen blowing and lime powder combined blowing converter |
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| CN114807497A (en) * | 2022-03-28 | 2022-07-29 | 邯郸钢铁集团有限责任公司 | Method for smelting high-silicon molten iron by using bottom oxygen blowing and lime powder combined blowing converter |
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