WO2022041994A1 - 一种铁浴熔融还原法生产超高纯生铁的方法 - Google Patents

一种铁浴熔融还原法生产超高纯生铁的方法 Download PDF

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WO2022041994A1
WO2022041994A1 PCT/CN2021/102376 CN2021102376W WO2022041994A1 WO 2022041994 A1 WO2022041994 A1 WO 2022041994A1 CN 2021102376 W CN2021102376 W CN 2021102376W WO 2022041994 A1 WO2022041994 A1 WO 2022041994A1
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furnace
iron
slag
smelting reduction
powder
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PCT/CN2021/102376
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English (en)
French (fr)
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张冠琪
王金霞
张晓峰
陈庆孟
韩军义
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山东墨龙石油机械股份有限公司
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Publication of WO2022041994A1 publication Critical patent/WO2022041994A1/zh
Priority to ZA2022/13056A priority Critical patent/ZA202213056B/en

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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/0006—Making spongy iron or liquid steel, by direct processes obtaining iron or steel in a molten state
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/0066—Preliminary conditioning of the solid carbonaceous reductant
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/14—Multi-stage processes processes carried out in different vessels or furnaces

Definitions

  • the application relates to a method for producing ultra-high-purity pig iron by an iron bath smelting reduction method, which belongs to the technical field of smelting reduction metallurgy.
  • ultra-high-purity pig iron can still be produced under the condition of using domestic low-grade raw materials, it will be beneficial to the development of domestic ultra-high-purity pig iron.
  • a method for producing ultra-high-purity pig iron by iron bath smelting reduction method is provided.
  • the method is to pre-oxidize the ore powder with lower grade before sending it into the smelting reduction furnace to reach 50-80%
  • the desulfurization rate and the arsenic removal rate of 30-40% are produced by controlling the production conditions in the smelting reduction furnace and the desulfurization outside the furnace to produce ultra-high-purity pig iron, and the method for producing ultra-high-purity pig iron through the iron bath smelting reduction method, It solves the problem of excessive dependence on high-quality raw materials for domestic production of ultra-high-purity pig iron.
  • the method for producing ultra-high-purity pig iron by the iron bath smelting reduction method comprises the following steps:
  • the raw materials into the furnace include ore powder, coal powder, magnesium-containing flux and limestone powder;
  • the pulverized coal and limestone powder are blown into the smelting reduction furnace through the pulverized coal injection system;
  • the initial molten iron By controlling the slag holding amount, molten iron liquid level, oxidizing gas amount, oxygen enrichment amount, injection depth, slag iron droplet carrying amount, heat load, raw fuel ratio and slag composition in the smelting reduction furnace, the initial molten iron;
  • the conditions for preheating and pre-oxidizing the mineral powder in the step (2) include:
  • the discharge temperature of the preheated and pre-oxidized mineral powder is controlled at 565-750°C.
  • the amount of slag in the step (3) is controlled within ( ⁇ (d/2) 2 ⁇ 3.45) ⁇ ( ⁇ (d/2) 2 ⁇ 5.75), wherein d is the melting point of the smelting reduction furnace
  • d is the melting point of the smelting reduction furnace
  • the cross-sectional diameter of the slag area, the unit of d is meters, and the unit of slag retention is tons.
  • control method of the slag retention includes:
  • the furnace pressure is raised to the second predetermined pressure
  • first predetermined pressure and the second predetermined pressure are both 40-90KPa, and the difference between the first predetermined pressure and the second predetermined pressure is 5-30KPa;
  • the pressure reduction speed is 0.5-2KPa/min;
  • the pressure rise speed is 0.5-1.5KPa/min
  • the condition for judging that the slag can be blocked after the slag discharge is completed is that the interval gasping time is less than 10s;
  • the one slag discharge cycle is from the completion of the previous slag discharge to the completion of the next slag discharge, and the duration of the one slag discharge cycle is 1.5-3.5h.
  • the molten iron level in the step (3) is controlled at 1.0-3.2m;
  • the control method of the molten iron level includes:
  • the distance between the molten iron level of the front furnace and the upper edge of the front furnace mouth is controlled at 0-50 cm, the furnace pressure is raised to the third predetermined pressure, and the third predetermined pressure is maintained for 5-15 minutes , and then reduce the furnace pressure to the fourth predetermined pressure;
  • the third predetermined pressure and the fourth predetermined pressure are both 40-90KPa, and the difference between the third predetermined pressure and the fourth predetermined pressure is 5-30KPa;
  • the pressure increase rate is 0.5-1.5KPa/min
  • the pressure reduction speed is 0.5-2KPa/min
  • the tapping temperature of molten iron is controlled at 1330-1450°C.
  • the amount of the oxidizing gas is controlled at 130000-300000Nm 3 /h, and the temperature of the oxidizing gas entering the furnace is controlled at 800-1280°C;
  • the oxygen-enriched amount includes controlling the proportion of industrial oxygen in the hot air per hour to be 14-24%;
  • the injection depth includes controlling the injection volume of the ore at 120-180t/h, and controlling the inlet pressure of the thermal ore gun at 100-300KPa;
  • the heat load includes controlling the heat load of the water wall at the molten pool slag to be 0.5-8.0MW, controlling the heat load of the water wall at the heat exchange area to be 2-15MW, and controlling the calorific value of the gas in the smelting reduction furnace to be 1.8. -3.5MJ/Nm 3 , control the oxygen distribution coefficient at 0.01-0.5;
  • the raw fuel ratio includes controlling the ratio of ore and pulverized coal to be 1:300-3:1;
  • the slag components include deep dephosphorization slag and deep desulfurization slag
  • the control conditions for the deep dephosphorization slag include controlling the content of ferrous oxide to be 7-10wt%, the content of magnesium oxide to be 7.5-10wt%, and the binary basicity to be controlled.
  • the slag temperature is 1380-1420°C
  • the control conditions of the deep desulfurization slag include controlling the content of ferrous oxide at 0-2wt%, the content of magnesium oxide at 7.5-10wt%, and the binary basicity at 1.30 -1.35, the slag temperature is 1420-1500°C.
  • the amount of iron droplets carried by the furnace gas slag is controlled at 0.75-5.00kg/Nm 3 ;
  • the method for controlling the amount of iron droplets carried by the furnace gas slag includes controlling the oxidation pressure of the upper part of the furnace body, the pressure in the furnace of the smelting reduction furnace, the flow rate of the material spray gun and the viscosity of the slag.
  • the pressure in the furnace is controlled at 40-90KPa
  • the flow rate of the material spray gun is controlled at 15000-35000Nm 3 /h
  • the slag viscosity is controlled at 0.2-0.6Pa ⁇ s.
  • the iron grade in the ore powder is not lower than 58wt%, the phosphorus content is not higher than 0.2wt%, the sulfur content is not higher than 0.05wt%, and the particle size is not higher than 20mm.
  • the content is not higher than 10wt%;
  • the fixed carbon content in the pulverized coal is not less than 75wt%, the volatile matter content is 5-15wt%, the sulfur content is not higher than 0.8wt%, and the particle size is not higher than 10mm.
  • the content is not higher than 10wt%;
  • the content of magnesium oxide in the magnesium-containing flux is not less than 17wt%, and the particle size is not higher than 20mm;
  • the content of calcium oxide in the limestone powder is not less than 75wt%, the activity degree is not less than 200, and the particle size is not higher than 3mm.
  • the iron content in the mineral powder is 58-60wt%
  • the phosphorus content is 0.10-0.12wt%
  • the sulfur content is 0.02-0.05wt%
  • the particle size is not higher than 20mm, and the particle size is not less than 4mm.
  • the content in the total mineral powder is 7-9wt%.
  • the desulfurization outside the furnace includes:
  • a compound desulfurizer is added to the ladle, the compound desulfurizer includes magnesium powder, lime powder and recarburizer, and the consumption of magnesium powder is controlled at 0.7-1.1kg/tHM; the consumption of lime powder is the consumption of magnesium powder 4-6 times of that, the consumption of recarburizer is 1-8kg/tHM, and the temperature of molten iron in the ladle is 1300-1350°C.
  • the chemical composition and weight percentage of the prepared ultra-high-purity pig iron include: C 3.3-4.2%, Si 0.001-0.05%, Mn 0.001-0.003%, P 0.005-0.008%, S 0.0001-0.001%, Ti 0.001-0.002%, Cr 0.0001-0.005%, V 0.0001-0.0008%, Mo 0.001-0.005%, Sn 0.0001-0.0002%, Sb 0.0001-0.0002%, Pb 0.00001-0.0001%, Bi 0.001% As, Bi 0.0000 0.0010%, Te 0.000001-0.00001%, B 0.00001-0.00050%, Al 0.0001-0.0020%, the balance is Fe.
  • the iron bath smelting reduction method is the HIsmelt smelting reduction method.
  • the smelting reduction furnace is an SRV furnace.
  • slag retention amount refers to the amount of slag stored in the molten pool in the smelting reduction furnace
  • Hot iron level means the level of molten iron stored in the iron bath area of the smelting reduction furnace
  • the amount of slag and iron droplets carried by the furnace gas refers to the amount of slag and iron droplets carried in the process of escaping the gas flow from the molten pool of the smelting reduction furnace and then rising again.
  • the iron oxides in the ore powder and the dissolved carbon undergo a reduction reaction to generate CO, which is mixed with the H2 generated by the cracking of the volatiles in the coal and the material injection carrier gas to form an upward airflow.
  • the airflow escaping from the molten pool drives the molten pool slag during the upward process.
  • the iron droplets move upward and have a strong stirring effect on the molten pool;
  • Amount of oxidizing gas means the total amount of oxygen-containing hot air gas
  • “Industrial pure oxygen” means an industrial gas whose oxygen purity is higher than 95%
  • Interval gasping refers to intermittent flashing at 1-6m from the outer edge of the composite slag mouth sleeve, similar to water flow, and the slag discharge process is a continuous jet of slag flow (similar to continuous water flow). gas, forming a discontinuous slag flow, similar to the gasping process, that is, the slag discharge is completed;
  • One slag discharge cycle refers to the completion of the last slag discharge to the completion of the next slag discharge
  • the “tapping interval” refers to the time period from when the furnace pressure is lowered to the fourth predetermined pressure after the last tapping is completed and before the furnace pressure is raised in the next tapping.
  • the method for producing ultra-high-purity pig iron according to the iron bath smelting reduction method of the present application pre-oxidizes the ore powder with a lower grade before sending it into the smelting reduction furnace to achieve a desulfurization rate of 50-80% And the arsenic removal rate of 30-40%, and then by controlling the production conditions in the smelting reduction furnace and the desulfurization outside the furnace, ultra-high-purity pig iron is produced.
  • the method of producing ultra-high-purity pig iron through the iron bath smelting reduction method solves the domestic The problem of excessive dependence on high-quality raw materials for the production of ultra-high-purity pig iron; and the pre-oxidation of mineral powder is conducive to reducing production costs and environmental protection in the production process.
  • magnesium-containing flux in the examples is described with dolomite powder, and the present invention is not limited to this type of magnesium-containing flux.
  • the iron bath smelting reduction method in the examples is the HIsmelt smelting reduction method, and the smelting reduction furnace is an SRV furnace.
  • the production method provided by the application produces ultra-high-purity pig iron.
  • the present embodiment provides a method for producing ultra-high-purity pig iron by an iron bath smelting reduction method, comprising the following steps:
  • the raw materials into the furnace include ore powder, coal powder, dolomite powder and limestone powder
  • the iron grade in the mineral powder is not lower than 58wt%, the phosphorus content is not higher than 0.2wt%, the sulfur content is not higher than 0.05wt%, and the particle size is not higher than 20mm.
  • the content in the powder is not higher than 10wt%;
  • Coal powder Coal is crushed and ground by a coal mill to obtain coal powder.
  • the fixed carbon content in the coal powder is not less than 75wt%, the volatile content is 5-15wt%, the sulfur content is not higher than 0.8wt%, and the particle size is not higher than 10mm , wherein the content of pulverized coal with a particle size of not less than 3mm in the total pulverized coal is not higher than 10wt%;
  • Dolomite powder the content of magnesium oxide in the dolomite powder is not less than 17wt%, and the particle size is not higher than 20mm;
  • Limestone powder the content of calcium oxide in limestone powder is not less than 75wt%, the activity degree is not less than 200, the particle size is not higher than 3mm, and the content of limestone powder with particle size not higher than 500 ⁇ m in the total limestone powder is not less than 80wt% .
  • the ore powder is preheated and pre-reacted in the rotary kiln.
  • the pulverized coal and limestone powder are blown into the smelting reduction furnace through the pulverized coal injection system;
  • the initial molten iron By controlling the slag holding amount, molten iron liquid level, oxidizing gas amount, oxygen enrichment amount, injection depth, slag iron droplet carrying amount, heat load, raw fuel ratio and slag composition in the smelting reduction furnace, the initial molten iron.
  • the furnace pressure is raised to the second predetermined pressure
  • first predetermined pressure and the second predetermined pressure are both 40-90KPa, and the difference between the first predetermined pressure and the second predetermined pressure is 5-30KPa;
  • the pressure reduction speed is 0.5-2KPa/min;
  • the pressure rise speed is 0.5-1.5KPa/min
  • the condition for judging that the slag can be blocked after the slag discharge is completed is that the interval gasping time is less than 10s;
  • the duration of a slag discharge cycle is 1.5-3.5h.
  • the molten iron level is controlled at 1.0-3.2m
  • the control methods of molten iron level include:
  • the distance between the molten iron level of the front furnace and the upper edge of the front furnace mouth is controlled at 0-50cm, the furnace pressure is raised to the third predetermined pressure, the third predetermined pressure is maintained for 5-15 minutes, and then reducing the furnace pressure to a fourth predetermined pressure;
  • the third predetermined pressure and the fourth predetermined pressure are both 40-90KPa, and the difference between the third predetermined pressure and the fourth predetermined pressure is 5-30KPa;
  • the pressure rise speed is 0.5-1.5KPa/min
  • the pressure reduction speed is 0.5-2KPa/min
  • the tapping temperature of molten iron is controlled at 1330-1450°C.
  • control conditions for the amount of oxidizing gas include:
  • the amount of oxidizing gas is controlled at 130000-300000Nm3/h, and the temperature of the oxidizing gas entering the furnace is controlled at 800-1280°C.
  • control conditions for oxygen enrichment include:
  • Control conditions for injection depth include:
  • the injection volume of ore is controlled at 120-180t/h, and the inlet pressure of the thermal ore gun is controlled at 100-300KPa.
  • control conditions for the amount of iron droplets carried by the furnace gas slag include:
  • the amount of iron droplets carried by the furnace gas slag is controlled at 0.20-0.75kg/Nm 3 ;
  • the method for controlling the amount of iron droplets carried by the furnace gas slag includes controlling the oxidation pressure of the upper part of the furnace body, the pressure in the furnace of the smelting reduction furnace, the flow rate of the material spray gun and the viscosity of the slag.
  • the oxidation pressure of the upper part of the furnace body is controlled at 100-300KPa.
  • the internal pressure is controlled at 40-90KPa, the flow rate of the material spray gun is controlled at 15000-35000Nm3/h, and the slag viscosity is controlled at 0.2-0.6Pa ⁇ s.
  • Control conditions for heat loads include:
  • the control conditions of the raw fuel ratio include:
  • control conditions of slag composition include the control conditions of deep dephosphorization slag and the control conditions of deep desulfurization slag:
  • the control conditions of the deep dephosphorization slag include controlling the content of ferrous oxide at 7-10wt%, the content of magnesium oxide at 7.5-10wt%, the binary basicity at 1.30-1.35, and the slag temperature at 1380-1420°C;
  • the control conditions of the deep desulfurization slag include controlling the content of ferrous oxide at 0-2wt%, the content of magnesium oxide at 7.5-10wt%, the binary basicity at 1.30-1.35, and the slag temperature at 1420-1500°C.
  • Out-of-furnace desulfurization includes:
  • the compound desulfurizer includes magnesium powder, lime powder and recarburizer.
  • the consumption of magnesium powder is controlled at 0.7-1.1kg/tHM; the consumption of lime powder is 4-6% of the consumption of magnesium powder. times, the consumption of recarburizer is 1-8kg/tHM, and the temperature of molten iron in the ladle is 1300-1350°C.
  • step (2) the mineral powder is preheated and pre-oxidized to remove the mineral powder. Sulfur and arsenic are preheated and pre-oxidized in the rotary kiln.
  • the conditions of pre-heating and pre-oxidation are as follows:
  • the discharge temperature of the preheated and pre-oxidized mineral powder is controlled at 565-750°C.
  • the above conditions satisfy the decomposition of the main sulfide in the mineral powder and the removal of sulfur combustion, so as to achieve a pre-desulfurization rate of 50-80% and a pre-arsenic removal rate of 30-40%.
  • the desulfurization rate of the initial molten iron smelted by the smelting reduction furnace in this embodiment is 90%-98%.
  • Example 1 the desulfurization rate of the initial molten iron smelted by the smelting reduction furnace is 80%-90%.
  • the pre-oxidation of the mineral powder in this embodiment is conducive to removing sulfur in molten iron, and the removal of sulfur in the rotary kiln is conducive to reducing the production cost of subsequent out-of-furnace desulfurization, and is conducive to protecting the environment.
  • Table 1 Comparison table between the chemical composition of ultra-high-purity pig iron prepared by the method in Example 2 and the chemical composition of ultra-high-purity pig iron produced by a domestic company
  • the content of trace elements in the ultra-high-purity pig iron prepared in this example is comparable to that in the high-purity pig iron produced by a domestic company, and even the content of some trace elements is far It is lower than the corresponding trace element content, but compared with the commonly used domestic method for producing high-purity pig iron from blast furnaces, the present application greatly reduces the production process flow, effectively improves the production efficiency, reduces the dependence on high-quality raw materials, and improves the product quality. quality, reducing pollutant emissions.
  • the present embodiment provides a method for producing ultra-high-purity pig iron by an iron bath smelting reduction method, comprising the following steps:
  • the raw materials into the furnace include ore powder, coal powder, dolomite powder and limestone powder
  • the iron content in the mineral powder is 58-60wt%, the phosphorus content is 0.10-0.12wt%, the sulfur content is 0.02-0.05wt%, and the particle size is not higher than 20mm.
  • the content in the mineral powder is 7-9wt%;
  • Coal powder Coal is crushed and ground by a coal mill to obtain coal powder.
  • the fixed carbon content in the coal powder is not less than 75wt%, the volatile content is 5-15wt%, the sulfur content is not higher than 0.8wt%, and the particle size is not higher than 10mm , wherein the content of pulverized coal with a particle size of not less than 3mm in the total pulverized coal is not higher than 10wt%;
  • Dolomite powder the content of magnesium oxide in the dolomite powder is not less than 17wt%, and the particle size is not higher than 20mm;
  • Limestone powder the content of calcium oxide in limestone powder is not less than 75wt%, the activity degree is not less than 200, the particle size is not higher than 3mm, and the content of limestone powder with particle size not higher than 500 ⁇ m in the total limestone powder is not less than 80wt% .
  • preheating and preoxidizing the ore powder to remove sulfur and arsenic in the ore powder, and preheating and preoxidizing the ore powder in the rotary kiln.
  • the conditions of preheating and preoxidation are as follows:
  • the discharge temperature of the preheated and pre-oxidized mineral powder is controlled at 565-750°C.
  • the above conditions satisfy the decomposition of the main sulfide in the mineral powder and the removal of sulfur combustion, so as to achieve a pre-desulfurization rate of 50-80% and a pre-arsenic removal rate of 30-40%.
  • the pulverized coal and limestone powder are blown into the smelting reduction furnace through the pulverized coal injection system;
  • the initial molten iron By controlling the slag holding amount, molten iron liquid level, oxidizing gas amount, oxygen enrichment amount, injection depth, slag iron droplet carrying amount, heat load, raw fuel ratio and slag composition in the smelting reduction furnace, the initial molten iron.
  • the furnace pressure is raised to the second predetermined pressure
  • first predetermined pressure and the second predetermined pressure are both 40-90KPa, and the difference between the first predetermined pressure and the second predetermined pressure is 5-30KPa;
  • the pressure reduction speed is 0.5-2KPa/min;
  • the pressure rise speed is 0.5-1.5KPa/min
  • the condition for judging that the slag can be blocked after the slag discharge is completed is that the interval gasping time is less than 10s;
  • the duration of a slag discharge cycle is 1.5-3.5h.
  • the molten iron level is controlled at 1.0-3.2m
  • the control methods of molten iron level include:
  • the distance between the molten iron level of the front furnace and the upper edge of the front furnace mouth is controlled at 0-50cm, the furnace pressure is raised to the third predetermined pressure, the third predetermined pressure is maintained for 5-15 minutes, and then reducing the furnace pressure to a fourth predetermined pressure;
  • the third predetermined pressure and the fourth predetermined pressure are both 40-90KPa, and the difference between the third predetermined pressure and the fourth predetermined pressure is 5-30KPa;
  • the pressure rise speed is 0.5-1.5KPa/min
  • the pressure reduction speed is 0.5-2KPa/min
  • the tapping temperature of molten iron is controlled at 1330-1450°C.
  • control conditions for the amount of oxidizing gas include:
  • the amount of oxidizing gas is controlled at 130000-300000Nm 3 /h, and the temperature of the oxidizing gas entering the furnace is controlled at 800-1280°C.
  • control conditions for oxygen enrichment include:
  • Control conditions for injection depth include:
  • the injection volume of ore is controlled at 120-180t/h, and the inlet pressure of the thermal ore gun is controlled at 100-300KPa.
  • control conditions for the amount of iron droplets carried by the furnace gas slag include:
  • the amount of iron droplets carried by the furnace gas slag is controlled at 0.20-0.75kg/Nm 3 ;
  • the method for controlling the amount of iron droplets carried by the furnace gas slag includes controlling the oxidation pressure of the upper part of the furnace body, the pressure in the furnace of the smelting reduction furnace, the flow rate of the material spray gun and the viscosity of the slag.
  • the oxidation pressure of the upper part of the furnace body is controlled at 100-300KPa.
  • the internal pressure is controlled at 40-90KPa, the flow rate of the material spray gun is controlled at 15000-35000Nm 3 /h, and the slag viscosity is controlled at 0.2-0.6Pa ⁇ s.
  • Control conditions for heat loads include:
  • the control conditions of the raw fuel ratio include:
  • control conditions of slag composition include the control conditions of deep dephosphorization slag and the control conditions of deep desulfurization slag:
  • the control conditions of the deep dephosphorization slag include controlling the content of ferrous oxide at 7-10wt%, the content of magnesium oxide at 7.5-10wt%, the binary basicity at 1.30-1.35, and the slag temperature at 1380-1420°C;
  • the control conditions of the deep desulfurization slag include controlling the content of ferrous oxide at 0-2wt%, the content of magnesium oxide at 7.5-10wt%, the binary basicity at 1.30-1.35, and the slag temperature at 1420-1500°C.
  • Out-of-furnace desulfurization includes:
  • the compound desulfurizer includes magnesium powder, lime powder and recarburizer.
  • the consumption of magnesium powder is controlled at 0.7-1.1kg/tHM; the consumption of lime powder is 4-6% of the consumption of magnesium powder. times, the consumption of recarburizer is 1-8kg/tHM, and the temperature of molten iron in the ladle is 1300-1350°C.
  • the desulfurization rate of the initial molten iron smelted by the smelting reduction furnace in this embodiment is 95%-99%.
  • the pre-oxidation of the mineral powder in this embodiment is conducive to removing sulfur in molten iron, and the removal of sulfur in the rotary kiln is conducive to reducing the production cost of subsequent out-of-furnace desulfurization, and is conducive to protecting the environment.
  • Table 2 Comparison table of chemical composition of ultra-high-purity pig iron prepared by the method in this example 3 and chemical composition of ultra-high-purity pig iron produced by a domestic company
  • this example adopts low-grade mineral powder with specific component content, and the content of trace elements in the prepared ultra-high-purity pig iron is equivalent to the content of trace elements in the high-purity pig iron produced by a domestic company.
  • the content of some trace elements is far lower than the corresponding trace element content, but compared with the domestic commonly used method for producing high-purity pig iron in blast furnaces, the present application greatly reduces the production process flow, effectively improves the production efficiency, and reduces the need for high-quality raw materials. Dependence, improve product quality and reduce pollutant emissions.

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Abstract

本申请涉及一种铁浴熔融还原法生产超高纯生铁的方法。该生产超高纯生铁的方法，包括如下步骤：筛选入炉原料，入炉原料包括矿粉、煤粉、含镁熔剂及石灰石粉；将矿粉进行预热及预氧化处理以脱除矿粉中的硫及砷；将预热及预氧化处理后的矿粉及含镁熔剂经矿粉喷吹系统吹入熔融还原炉；将煤粉以及石灰石粉经煤粉喷吹系统吹入熔融还原炉；通过控制熔融还原炉内的生产条件，制得初始铁水；将初始铁水经炉外脱硫，制得超高纯生铁。该方法通过将品位较低的矿粉在送入熔融还原炉之前，先进行预氧化，达到50-80％的脱硫率以及30-40％的脱砷率，再通过控制熔融还原炉内的生产条件及炉外脱硫，生产出超高纯生铁，解决了国内生产超高纯生铁对优质原料过度依赖的问题。

Description

一种铁浴熔融还原法生产超高纯生铁的方法 技术领域
本申请涉及一种铁浴熔融还原法生产超高纯生铁的方法，属于熔融还原冶金技术领域。
背景技术
随着我国由铸造大国向铸造强国转型，国内汽车、风电、船舶、化工、高速列车等行业的发展，对高纯生铁特别是超高纯生铁的需求量日趋增大，但我国的铸造生铁普遍存在钛、磷含量偏高和杂质、微量元素超标的问题，大量优质铸造用高纯生铁及超高纯生铁仍然依赖进口。
在国内，大多数高纯生铁和优质铸造生铁均采用精选炉料、优化高炉冶炼工艺的方法生产，即精心选用P、S等有害杂质元素都很低的优质精矿粉对其烧结。由于通过高炉生产高纯生铁及超高纯生铁对优质原料的依赖性较强，而国内的优质原料有限，我国每年从澳大利亚、巴西等国进口大量铁矿石，严重制约了国内高纯生铁及超高纯生铁的生产与供应关系，而且国内储量丰富的低品位及高磷矿、钒钛矿等没有得到有效的开发利用。
如果在使用国内低品位的原料的条件下，仍能生产出超高纯生铁，将有利于国内超高纯生铁的发展。
发明内容
为了解决上述问题，提供了一种铁浴熔融还原法生产超高纯生铁 的方法，该方法通过将品位较低的矿粉在送入熔融还原炉之前，先进行预氧化，达到50-80％的脱硫率以及30-40％的脱砷率，再通过控制熔融还原炉内的生产条件及炉外脱硫，生产出超高纯生铁，通过该铁浴熔融还原法生产超高纯生铁的方法，解决了国内生产超高纯生铁对优质原料过度依赖的问题。
所述铁浴熔融还原法生产超高纯生铁的方法，包括如下步骤：
(1)筛选入炉原料，入炉原料包括矿粉、煤粉、含镁熔剂及石灰石粉；
(2)将矿粉进行预热及预氧化处理以脱除矿粉中的硫及砷；
(3)将预热及预氧化处理后的矿粉及含镁熔剂经矿粉喷吹系统吹入熔融还原炉；
将煤粉以及石灰石粉经煤粉喷吹系统吹入熔融还原炉；
通过控制熔融还原炉内的炉渣保有量、铁水液面、氧化气体量、富氧量、喷吹深度、炉气渣铁液滴携带量、热负荷、原燃料配比以及炉渣成分，制得初始铁水；
(4)将所述初始铁水经炉外脱硫，制得超高纯生铁。
优选的，所述步骤(2)的矿粉进行预热及预氧化处理的条件包括：
控制燃烧煤气用量占熔融还原炉产出煤气量的15％-35％；
控制富氧热风含氧量在21％-32％；
控制经预热及预氧化处理后的矿粉的出料温度在565-750℃。
优选的，所述步骤(3)中的炉渣保有量控制在(π×(d/2) 2×3.45)～(π×(d/2) 2×5.75)，其中d为熔融还原炉的熔池渣区的横截面直径， d的单位为米，炉渣保有量的单位为吨。
优选的，所述炉渣保有量的控制方法包括：
在一个排渣周期内，在出渣开始后的10min内，将炉压降至第一预定压力；
在出渣结束后的50min内，将炉压升至第二预定压力；
其中，所述第一预定压力和所述第二预定压力均为40-90KPa，且所述第一预定压力与所述第二预定压力的差值为5-30KPa；
将炉压降低至所述第一预定压力时压力降低速度为0.5-2KPa/min；
将炉压升高至第二预定压力时压力升高速度为0.5-1.5KPa/min；
判断出渣完毕可以堵口的条件为间隔喘气时间小于10s；
所述一个排渣周期为上一次出渣完毕至下一次出渣完毕，所述一个排渣周期的时长为1.5-3.5h。
优选的，所述步骤(3)中的铁水液面控制在1.0-3.2m；
所述铁水液面的控制方法包括：
在出渣结束后的50min内，将前置炉铁水液面距离前置炉口上沿的距离控制在0-50cm，将炉压升至第三预定压力，保持所述第三预定压力5-15min，再将炉压降至第四预定压力；
其中，所述第三预定压力和所述第四预定压力均为40-90KPa，且第三预定压力与所述第四预定压力的差值为5-30KPa；
将炉压升高至所述第三预定压力时压力升高速度为0.5-1.5KPa/min；
将炉压降低至所述第四预定压力时压力降低速度为0.5-2KPa/min；
控制出铁间隔在5-10min；
铁水的出铁温度控制在1330-1450℃。
优选的，在所述步骤(3)中，
所述氧化气体量控制在130000-300000Nm 3/h，氧化气体入炉温度控制在800-1280℃；
所述富氧量包括控制每小时热风中工业氧气的配入量在14-24％；
所述喷吹深度包括将矿石的喷吹量控制在120-180t/h，将热矿枪的入口压力控制在100-300KPa；
所述热负荷包括控制熔池熔渣处的水冷壁的热负荷在0.5-8.0MW，控制换热区处的水冷壁的热负荷在2-15MW，控制熔融还原炉内的煤气热值在1.8-3.5MJ/Nm 3，控制氧分配系数在0.01-0.5；
所述原燃料配比包括控制矿石与煤粉的配比在1:300-3:1；
所述炉渣成分包括深脱磷渣及深脱硫渣，所述深脱磷渣的控制条件包括控制氧化亚铁的含量在7-10wt％，氧化镁的含量在7.5-10wt％，二元碱度在1.30-1.35，炉渣温度在1380-1420℃；所述深脱硫渣的控制条件包括控制氧化亚铁的含量在0-2wt％，氧化镁的含量在7.5-10wt％，二元碱度在1.30-1.35，炉渣温度在1420-1500℃。
优选的，所述步骤(3)中炉气渣铁液滴携带量控制在0.75-5.00kg/Nm 3；
所述炉气渣铁液滴携带量的控制方法，包括控制炉体上部氧化压 力、熔融还原炉炉内压力、物料喷枪的流量以及炉渣黏度，炉体上部氧化压力控制在100-300KPa,熔融还原炉炉内压力控制在40-90KPa，物料喷枪的流量控制在15000-35000Nm 3/h,炉渣黏度控制在0.2-0.6Pa·s。
优选的，在所述步骤(1)中，
矿粉中铁品位不低于58wt％，磷含量不高于0.2wt％，硫含量不高于0.05wt％，粒度不高于20mm，其中，粒度不低于4mm的矿粉在总矿粉中的含量不高于10wt％；
煤粉中固定碳含量不低于75wt％，挥发分含量在5-15wt％，硫含量不高于0.8wt％，粒度不高于10mm，其中，粒度不低于3mm的煤粉在总煤粉中的含量不高于10wt％；
含镁熔剂中氧化镁的含量不低于17wt％，粒度不高于20mm；
石灰石粉中氧化钙的含量不低于75wt％，活性度不低于200，粒度不高于3mm，其中粒度不高于500μm的石灰石粉在总石灰石粉中的含量不低于80wt％。
优选的，所述矿粉中铁品位含量为58-60wt％，磷含量为0.10-0.12wt％，硫含量为0.02-0.05wt％，粒度不高于20mm，其中，粒度不低于4mm的矿粉在总矿粉中的含量为7-9wt％。
优选的，在所述步骤(4)中，所述炉外脱硫包括：
向铁水包中添加复合脱硫剂，所述复合脱硫剂包括镁粉、石灰粉和增碳剂，镁粉消耗量控制在0.7-1.1kg/tHM；石灰粉消耗量的消耗量为镁粉消耗量的4-6倍，增碳剂消耗量1-8kg/tHM，所述铁水包内 铁水温度1300-1350℃。
优选的，制得的超高纯生铁的化学组分及重量百分比包括：C 3.3-4.2％，Si 0.001-0.05％，Mn 0.001-0.003％，P 0.005-0.008％，S 0.0001-0.001％，Ti 0.001-0.002％，Cr 0.0001-0.005％，V 0.0001-0.0008％，Mo 0.001-0.005％，Sn 0.0001-0.0002％，Sb 0.0001-0.0002％，Pb 0.00001-0.0001％，Bi 0.000001-0.00001％，As 0.0001-0.0010％，Te 0.000001-0.00001％，B 0.00001-0.00050％，Al 0.0001-0.0020％，余量为Fe。
优选的，铁浴熔融还原法为HIsmelt熔融还原法。
优选的，熔融还原炉为SRV炉。
本申请中，“炉渣保有量”，是指在熔融还原炉内熔池存储的炉渣量；
“铁水液面”，是指在熔融还原炉铁浴区中存储的铁水的高度；
“炉气渣铁液滴携带量”，是指熔融还原炉熔池逸出气流再上升过程中携带的渣铁液滴量。矿粉中铁氧化物与溶解碳发生还原反应产生CO，同煤中挥发分裂解产生的H 2以及物料喷吹载气混合形成上升的气流，逸出熔池的气流在上升过程中带动熔池渣铁液滴向上运动并对熔池起到强烈的搅拌效果；
“氧化气体量”，是指含氧热风气体总量；
“工业纯氧”，是指氧气的纯度高于95％的工业用气体；
“间隔喘气”，是指复合渣口套外沿1-6m处间断性拉闪光，类似于水流，出渣过程为连续性喷射渣流(类似于连续水流)，当出渣末期渣流中混入气体、形成不连续渣流，类似于喘气过程，即为出渣完毕；
“一个排渣周期”，是指上一次出渣完毕至下一次出渣完毕；
“出铁间隔”，是指设定上一次出铁完毕后将炉压降至第四预定压力至下一次出铁开始将炉压升高前的时间段。
本申请的有益效果包括但不限于：
1.根据本申请的铁浴熔融还原法生产超高纯生铁的方法，该方法通过将品位较低的矿粉在送入熔融还原炉之前，先进行预氧化，达到50-80％的脱硫率以及30-40％的脱砷率，再通过控制熔融还原炉内的生产条件及炉外脱硫，生产出超高纯生铁，通过该铁浴熔融还原法生产超高纯生铁的方法，解决了国内生产超高纯生铁对优质原料过度依赖的问题；而且对矿粉进行预氧化有利于降低生产成本，有利于生产过程的环保。
2.根据本申请的铁浴熔融还原法生产超高纯生铁的方法，相较于现有技术的高炉生产超高纯生铁，以较短的工艺生产优质超高纯生铁，有效缩短了工艺流程，减少了生产工序。
3.根据本申请的铁浴熔融还原法生产超高纯生铁的方法，通过控制熔融还原炉内的生产条件，将C、Mn、P、Pb、Sn、As、Sb、Bi等元素控制在超高纯生铁要求的控制范围，极大的提高了铁水纯净度。
具体实施方式
下面结合实施例详述本申请，但本申请并不局限于这些实施例。
实施例中的含镁熔剂以白云石粉进行说明，本发明不限于该类含镁熔剂。
实施例中的铁浴熔融还原法为HIsmelt熔融还原法，熔融还原炉为SRV炉，可以理解的是，通过在SRV炉的基础上对炉体进行改进后的熔融还原炉，也可通过使用本申请提供的生产方法生产超高纯生 铁。
实施例1
本实施例提供了一种铁浴熔融还原法生产超高纯生铁的方法，包括如下步骤：
(1)筛选入炉原料，入炉原料包括矿粉、煤粉、白云石粉及石灰石粉
各原料需要满足的条件如下：
矿粉：矿粉中铁品位不低于58wt％，磷含量不高于0.2wt％，硫含量不高于0.05wt％，粒度不高于20mm，其中，粒度不低于4mm的矿粉在总矿粉中的含量不高于10wt％；
煤粉：煤经磨煤机破碎、研磨得到煤粉，煤粉中固定碳含量不低于75wt％，挥发分含量在5-15wt％，硫含量不高于0.8wt％，粒度不高于10mm，其中，粒度不低于3mm的煤粉在总煤粉中的含量不高于10wt％；
白云石粉，白云石粉中氧化镁的含量不低于17wt％，粒度不高于20mm；
石灰石粉：石灰石粉中氧化钙的含量不低于75wt％，活性度不低于200，粒度不高于3mm，其中粒度不高于500μm的石灰石粉在总石灰石粉中的含量不低于80wt％。
(2)将矿粉进行预热处理
在回转窑内对矿粉进行预热及预反应处理。
(3)将各原料吹入熔融还原炉内，并控制熔融还原炉内的反应 条件
将预热后的矿粉及白云石粉经矿粉喷吹系统吹入熔融还原炉；
将煤粉以及石灰石粉经煤粉喷吹系统吹入熔融还原炉；
通过控制熔融还原炉内的炉渣保有量、铁水液面、氧化气体量、富氧量、喷吹深度、炉气渣铁液滴携带量、热负荷、原燃料配比以及炉渣成分，制得初始铁水。
在本实施例中的炉渣保有量控制在80-200t，由于不同的熔融还原炉其熔池渣区的横截面的直径不同，可以根据公式：炉渣保有量＝(π×(d/2) 2×3.45)～(π×(d/2) 2×5.75)进行计算，d为熔融还原炉的熔池渣区的横截面直径，d的单位为米，炉渣保有量的单位为吨；
熔渣保有量的具体控制方法，如下：
在一个排渣周期内，在出渣开始后的10min内，将炉压降至第一预定压力；
在出渣结束后的50min内，将炉压升至第二预定压力；
其中，第一预定压力和第二预定压力均为40-90KPa，且第一预定压力与第二预定压力的差值为5-30KPa；
将炉压降低至第一预定压力时压力降低速度为0.5-2KPa/min；
将炉压升高至第二预定压力时压力升高速度为0.5-1.5KPa/min；
判断出渣完毕可以堵口的条件为间隔喘气时间小于10s；
一个排渣周期的时长为1.5-3.5h。
在本实施例中，将铁水液面控制在1.0-3.2m；
铁水液面的控制方法包括：
在出渣结束后的50min内，将前置炉铁水液面距离前置炉口上沿的距离控制在0-50cm，将炉压升至第三预定压力，保持第三预定压力5-15min，再将炉压降至第四预定压力；
其中，第三预定压力和第四预定压力均为40-90KPa，且第三预定压力与第四预定压力的差值为5-30KPa；
将炉压升高至第三预定压力时压力升高速度为0.5-1.5KPa/min；
将炉压降低至第四预定压力时压力降低速度为0.5-2KPa/min；
控制出铁间隔在5-10min；
铁水的出铁温度控制在1330-1450℃。
氧化气体量的控制条件包括：
将氧化气体量控制在130000-300000Nm3/h，氧化气体入炉温度控制在800-1280℃。
富氧量的控制条件包括：
控制每小时热风中工业氧气的配入量在14-24％。
喷吹深度的控制条件包括：
将矿石的喷吹量控制在120-180t/h，将热矿枪的入口压力控制在100-300KPa。
炉气渣铁液滴携带量的控制条件包括：
炉气渣铁液滴携带量控制在0.20-0.75kg/Nm 3；
炉气渣铁液滴携带量的控制方法，包括控制炉体上部氧化压力、熔融还原炉炉内压力、物料喷枪的流量以及炉渣黏度，炉体上部氧化压力控制在100-300KPa,熔融还原炉炉内压力控制在40-90KPa，物 料喷枪的流量控制在15000-35000Nm3/h,炉渣黏度控制在0.2-0.6Pa·s。
热负荷的控制条件包括：
控制熔池熔渣处的水冷壁的热负荷在0.5-8.0MW，控制换热区处的水冷壁的热负荷在2-15MW，控制熔融还原炉内的煤气热值在1.8-3.5MJ/Nm3，控制氧分配系数在0.01-0.5。
原燃料配比的控制条件包括：
控制矿石粉与煤粉的配比在1:300-3:1。
炉渣成分的控制条件包括深脱磷渣的控制条件及深脱硫渣的控制条件：
深脱磷渣的控制条件包括控制氧化亚铁的含量在7-10wt％，氧化镁的含量在7.5-10wt％，二元碱度在1.30-1.35，炉渣温度在1380-1420℃；
深脱硫渣的控制条件包括控制氧化亚铁的含量在0-2wt％，氧化镁的含量在7.5-10wt％，二元碱度在1.30-1.35，炉渣温度在1420-1500℃。
(4)将初始铁水经炉外脱硫，制得超高纯生铁。
炉外脱硫包括：
向铁水包中添加复合脱硫剂，复合脱硫剂包括镁粉、石灰粉和增碳剂，镁粉消耗量控制在0.7-1.1kg/tHM；石灰粉的消耗量为镁粉消耗量的4-6倍，增碳剂消耗量1-8kg/tHM，铁水包内铁水温度1300-1350℃。
实施例2
本实施例与实施例1相同的技术特征不再赘述，本实施例与实施例1不同的技术特征在于，步骤(2)中将矿粉进行预热及预氧化处理以脱除矿粉中的硫及砷，在回转窑内对矿粉进行预热及预氧化处理，预热及预氧化的条件如下：
控制燃烧煤气用量占熔融还原炉产出煤气量的15％-35％；
控制富氧热风含氧量在21％-32％；
控制经预热及预氧化处理后的矿粉的出料温度在565-750℃。
上述条件满足矿粉中主要硫化物的分解及硫燃烧的去除，以实现预脱硫率在50-80％，预脱砷率在30-40％。
本实施例经熔融还原炉冶炼后的初始铁水的脱硫率为90％-98％。
实施例1中经熔融还原炉冶炼后的初始铁水的脱硫率为80％-90％。
可见，本实施例的矿粉经预氧化后，有利于去除铁水中的硫，且在回转窑中去除硫有利于降低后序炉外脱硫生产成本，有利于保护环境。
本实施例制得的超高纯生铁的化学成分见表1。
表1：通过本实施例2中的方法制备的超高纯生铁的化学成分与国内某公司生产的超高纯生铁的化学成分的对比表
Figure PCTCN2021102376-appb-000001
Figure PCTCN2021102376-appb-000002
通过表1可以看出，除了微量元素Mo外，本实施例制备的超高纯生铁中微量元素的含量与国内某公司生产的高纯生铁中的微量元素含量相当甚至某些微量元素的含量远低于相应的微量元素含量，但本申请相较于国内常用的高炉生产高纯生铁的方法，大大缩减了生产工艺流程，有效提高了生产效率，且降低了对优质原料的依赖，提高了产品质量，减少了污染物的排放。
实施例3
本实施例提供了一种铁浴熔融还原法生产超高纯生铁的方法，包括如下步骤：
(1)筛选入炉原料，入炉原料包括矿粉、煤粉、白云石粉及石灰石粉
各原料需要满足的条件如下：
矿粉：矿粉中铁品位含量为58-60wt％，磷含量为0.10-0.12wt％，硫含量为0.02-0.05wt％，粒度不高于20mm，其中，粒度不低于4mm的矿粉在总矿粉中的含量为7-9wt％；
煤粉：煤经磨煤机破碎、研磨得到煤粉，煤粉中固定碳含量不低于75wt％，挥发分含量在5-15wt％，硫含量不高于0.8wt％，粒度不高于10mm，其中，粒度不低于3mm的煤粉在总煤粉中的含量不高于10wt％；
白云石粉，白云石粉中氧化镁的含量不低于17wt％，粒度不高于20mm；
石灰石粉：石灰石粉中氧化钙的含量不低于75wt％，活性度不低于200，粒度不高于3mm，其中粒度不高于500μm的石灰石粉在总石灰石粉中的含量不低于80wt％。
(2)将矿粉进行预热及预氧化处理以脱除矿粉中的硫及砷，在回转窑内对矿粉进行预热及预氧化处理，预热及预氧化的条件如下：
控制燃烧煤气用量占熔融还原炉产出煤气量的15％-35％；
控制富氧热风含氧量在21％-32％；
控制经预热及预氧化处理后的矿粉的出料温度在565-750℃。
上述条件满足矿粉中主要硫化物的分解及硫燃烧的去除，以实现预脱硫率在50-80％，预脱砷率在30-40％。
(3)将各原料吹入熔融还原炉内，并控制熔融还原炉内的反应条件
将预热后的矿粉及白云石粉经矿粉喷吹系统吹入熔融还原炉；
将煤粉以及石灰石粉经煤粉喷吹系统吹入熔融还原炉；
通过控制熔融还原炉内的炉渣保有量、铁水液面、氧化气体量、富氧量、喷吹深度、炉气渣铁液滴携带量、热负荷、原燃料配比以及炉渣成分，制得初始铁水。
在本实施例中的炉渣保有量控制在80-200t，由于不同的熔融还原炉其熔池渣区的横截面的直径不同，可以根据公式：炉渣保有量＝(π×(d/2) 2×3.45)～(π×(d/2) 2×5.75)进行计算，d为熔融还原炉的熔 池渣区的横截面直径，d的单位为米，炉渣保有量的单位为吨；
熔渣保有量的具体控制方法，如下：
在一个排渣周期内，在出渣开始后的10min内，将炉压降至第一预定压力；
在出渣结束后的50min内，将炉压升至第二预定压力；
其中，第一预定压力和第二预定压力均为40-90KPa，且第一预定压力与第二预定压力的差值为5-30KPa；
将炉压降低至第一预定压力时压力降低速度为0.5-2KPa/min；
将炉压升高至第二预定压力时压力升高速度为0.5-1.5KPa/min；
判断出渣完毕可以堵口的条件为间隔喘气时间小于10s；
一个排渣周期的时长为1.5-3.5h。
在本实施例中，将铁水液面控制在1.0-3.2m；
铁水液面的控制方法包括：
在出渣结束后的50min内，将前置炉铁水液面距离前置炉口上沿的距离控制在0-50cm，将炉压升至第三预定压力，保持第三预定压力5-15min，再将炉压降至第四预定压力；
其中，第三预定压力和第四预定压力均为40-90KPa，且第三预定压力与第四预定压力的差值为5-30KPa；
将炉压升高至第三预定压力时压力升高速度为0.5-1.5KPa/min；
将炉压降低至第四预定压力时压力降低速度为0.5-2KPa/min；
控制出铁间隔在5-10min；
铁水的出铁温度控制在1330-1450℃。
氧化气体量的控制条件包括：
将氧化气体量控制在130000-300000Nm 3/h，氧化气体入炉温度控制在800-1280℃。
富氧量的控制条件包括：
控制每小时热风中工业氧气的配入量在14-24％。
喷吹深度的控制条件包括：
将矿石的喷吹量控制在120-180t/h，将热矿枪的入口压力控制在100-300KPa。
炉气渣铁液滴携带量的控制条件包括：
炉气渣铁液滴携带量控制在0.20-0.75kg/Nm 3；
炉气渣铁液滴携带量的控制方法，包括控制炉体上部氧化压力、熔融还原炉炉内压力、物料喷枪的流量以及炉渣黏度，炉体上部氧化压力控制在100-300KPa,熔融还原炉炉内压力控制在40-90KPa，物料喷枪的流量控制在15000-35000Nm 3/h,炉渣黏度控制在0.2-0.6Pa·s。
热负荷的控制条件包括：
控制熔池熔渣处的水冷壁的热负荷在0.5-8.0MW，控制换热区处的水冷壁的热负荷在2-15MW，控制熔融还原炉内的煤气热值在1.8-3.5MJ/Nm 3，控制氧分配系数在0.01-0.5。
原燃料配比的控制条件包括：
控制矿石粉与煤粉的配比在1:300-3:1。
炉渣成分的控制条件包括深脱磷渣的控制条件及深脱硫渣的控制条件：
深脱磷渣的控制条件包括控制氧化亚铁的含量在7-10wt％，氧化镁的含量在7.5-10wt％，二元碱度在1.30-1.35，炉渣温度在1380-1420℃；
深脱硫渣的控制条件包括控制氧化亚铁的含量在0-2wt％，氧化镁的含量在7.5-10wt％，二元碱度在1.30-1.35，炉渣温度在1420-1500℃。
(4)将初始铁水经炉外脱硫，制得超高纯生铁。
炉外脱硫包括：
向铁水包中添加复合脱硫剂，复合脱硫剂包括镁粉、石灰粉和增碳剂，镁粉消耗量控制在0.7-1.1kg/tHM；石灰粉的消耗量为镁粉消耗量的4-6倍，增碳剂消耗量1-8kg/tHM，铁水包内铁水温度1300-1350℃。
本实施例经熔融还原炉冶炼后的初始铁水的脱硫率为95％-99％。
可见，本实施例的矿粉经预氧化后，有利于去除铁水中的硫，且在回转窑中去除硫有利于降低后序炉外脱硫生产成本，有利于保护环境。
本实施例制得的超高纯生铁的化学成分见表2。
表2：通过本实施例3中的方法制备的超高纯生铁的化学成分与国内某公司生产的超高纯生铁的化学成分的对比表
Figure PCTCN2021102376-appb-000003
Figure PCTCN2021102376-appb-000004
通过表2可以看出，本实施例采用具有特定组分含量的低品位矿粉，制备的超高纯生铁中微量元素的含量与国内某公司生产的高纯生铁中的微量元素含量相当甚至某些微量元素的含量远低于相应的微量元素含量，但本申请相较于国内常用的高炉生产高纯生铁的方法，大大缩减了生产工艺流程，有效提高了生产效率，且降低了对优质原料的依赖，提高了产品质量，减少了污染物的排放。
以上所述，仅为本申请的实施例而已，本申请的保护范围并不受这些具体实施例的限制，而是由本申请的权利要求书来确定。对于本领域技术人员来说，本申请可以有各种更改和变化。凡在本申请的技术思想和原理之内所作的任何修改、等同替换、改进等，均应包含在本申请的保护范围之内。

Claims (11)

  1. 一种铁浴熔融还原法生产超高纯生铁的方法，其特征在于，包括如下步骤：
    (1)筛选入炉原料，入炉原料包括矿粉、煤粉、含镁熔剂及石灰石粉；
    (2)将所述矿粉进行预热及预氧化处理以脱除矿粉中的硫及砷；
    (3)将预热及预氧化处理后的矿粉及含镁熔剂经矿粉喷吹系统吹入熔融还原炉；
    将煤粉以及石灰石粉经煤粉喷吹系统吹入熔融还原炉；
    通过控制熔融还原炉内的炉渣保有量、铁水液面、氧化气体量、富氧量、喷吹深度、炉气渣铁液滴携带量、热负荷、原燃料配比以及炉渣成分，制得初始铁水；
    (4)将所述初始铁水经炉外脱硫，制得超高纯生铁。
  2. 根据权利要求1所述的铁浴熔融还原法生产超高纯生铁的方法，其特征在于，所述步骤(2)的矿粉进行预热及预氧化处理的条件包括：
    控制燃烧煤气用量占熔融还原炉产出煤气量的15％-35％；
    控制富氧热风含氧量在21％-32％；
    控制经预热及预氧化处理后的矿粉的出料温度在565-750℃。
  3. 根据权利要求1所述的铁浴熔融还原法生产超高纯生铁的方法，其特征在于，所述步骤(3)中的炉渣保有量控制在(π×(d/2) 2×3.45)～(π×(d/2) 2×5.75)，其中d为熔融还原炉的熔池渣区的横截面直径，d的单位为米，炉渣保有量的单位为吨。
  4. 根据权利要求3所述的铁浴熔融还原法生产超高纯生铁的方法，其特征在于，所述炉渣保有量的控制方法包括：
    在一个排渣周期内，在出渣开始后的10min内，将炉压降至第一预定压力；
    在出渣结束后的50min内，将炉压升至第二预定压力；
    其中，所述第一预定压力和所述第二预定压力均为40-90KPa，且所述第一预定压力与所述第二预定压力的差值为5-30KPa；
    将炉压降低至所述第一预定压力时压力降低速度为0.5-2KPa/min；
    将炉压升高至第二预定压力时压力升高速度为0.5-1.5KPa/min；
    判断出渣完毕可以堵口的条件为间隔喘气时间小于10s；
    所述一个排渣周期的时长为1.5-3.5h。
  5. 根据权利要求1所述的铁浴熔融还原法生产超高纯生铁的方法，其特征在于，所述步骤(3)中的铁水液面控制在1.0-3.2m；
    所述铁水液面的控制方法包括：
    在出渣结束后的50min内，将前置炉铁水液面距离前置炉口上沿的距离控制在0-50cm，将炉压升至第三预定压力，保持所述第三预定压力5-15min，再将炉压降至第四预定压力；
    其中，所述第三预定压力和所述第四预定压力均为40-90KPa，且第三预定压力与所述第四预定压力的差值为5-30KPa；
    将炉压升高至所述第三预定压力时压力升高速度为0.5-1.5KPa/min；
    将炉压降低至所述第四预定压力时压力降低速度为0.5-2KPa/min；
    控制出铁间隔在5-10min；
    铁水的出铁温度控制在1330-1450℃。
  6. 根据权利要求1所述的铁浴熔融还原法生产超高纯生铁的方法，其特征在于，在所述步骤(3)中，
    所述氧化气体量控制在130000-300000Nm 3/h，氧化气体入炉温度控制在800-1280℃；
    所述富氧量包括控制每小时热风中工业氧气的配入量在14-24％；
    所述喷吹深度包括将矿石的喷吹量控制在120-180t/h，将热矿枪的入口压力控制在100-300KPa；
    所述热负荷包括控制熔池熔渣处的水冷壁的热负荷在0.5-8.0MW，控制换热区处的水冷壁的热负荷在2-15MW，控制熔融还原炉内的煤气热值在1.8-3.5MJ/Nm 3，控制氧分配系数在0.01-0.5；
    所述原燃料配比包括控制矿石与煤粉的配比在1:300-3:1；
    所述炉渣成分包括深脱磷渣及深脱硫渣，所述深脱磷渣的控制条件包括控制氧化亚铁的含量在7-10wt％，氧化镁的含量在7.5-10wt％，二元碱度在1.30-1.35，炉渣温度在1380-1420℃；所述深脱硫渣的控制条件包括控制氧化亚铁的含量在0-2wt％，氧化镁的含量在7.5-10wt％，二元碱度在1.30-1.35，炉渣温度在1420-1500℃。
  7. 根据权利要求1所述的铁浴熔融还原法生产超高纯生铁的方法，其特征在于，所述步骤(3)中炉气渣铁液滴携带量控制在0.75-5.00 kg/Nm 3；
    所述炉气渣铁液滴携带量的控制方法，包括控制炉体上部氧化压力、熔融还原炉炉内压力、物料喷枪的流量以及炉渣黏度，炉体上部氧化压力控制在100-300KPa,熔融还原炉炉内压力控制在40-90KPa，物料喷枪的流量控制在15000-35000Nm 3/h,炉渣黏度控制在0.2-0.6Pa·s。
  8. 根据权利要求1所述的铁浴熔融还原法生产超高纯生铁的方法，其特征在于，在所述步骤(1)中，
    矿粉中铁品位不低于58wt％，磷含量不高于0.2wt％，硫含量不高于0.05wt％，粒度不高于20mm，其中，粒度不低于4mm的矿粉在总矿粉中的含量不高于10wt％；
    煤粉中固定碳含量不低于75wt％，挥发分含量在5-15wt％，硫含量不高于0.8wt％，粒度不高于10mm，其中，粒度不低于3mm的煤粉在总煤粉中的含量不高于10wt％；
    含镁熔剂中氧化镁的含量不低于17wt％，粒度不高于20mm；
    石灰石粉中氧化钙的含量不低于75wt％，活性度不低于200，粒度不高于3mm，其中粒度不高于500μm的石灰石粉在总石灰石粉中的含量不低于80wt％。
  9. 根据权利要求8所述的铁浴熔融还原法生产超高纯生铁的方法，其特征在于，所述矿粉中铁品位含量为58-60wt％，磷含量为0.10-0.12wt％，硫含量为0.02-0.05wt％，粒度不高于20mm，其中，粒度不低于4mm的矿粉在总矿粉中的含量为7-9wt％。
  10. 根据权利要求1所述的铁浴熔融还原法生产超高纯生铁的方法，其特征在于，在所述步骤(4)中，所述炉外脱硫包括：
    向铁水包中添加复合脱硫剂，所述复合脱硫剂包括镁粉、石灰粉和增碳剂，镁粉消耗量控制在0.7-1.1kg/tHM；石灰粉的消耗量为镁粉消耗量的4-6倍，增碳剂消耗量控制在1-8kg/tHM，所述铁水包内铁水温度1300-1350℃。
  11. 根据权利要求1所述的铁浴熔融还原法生产超高纯生铁的方法，其特征在于，制得的超高纯生铁的化学组分及重量百分比包括：C 3.3-4.2％，Si 0.001-0.05％，Mn 0.001-0.003％，P 0.005-0.008％，S 0.0001-0.001％，Ti 0.001-0.002％，Cr 0.0001-0.005％，V 0.0001-0.0008％，Mo 0.001-0.005％，Sn 0.0001-0.0002％，Sb 0.0001-0.0002％，Pb 0.00001-0.0001％，Bi 0.000001-0.00001％，As 0.0001-0.0010％，Te 0.000001-0.00001％，B 0.00001-0.00050％，Al 0.0001-0.0020％，余量为Fe。
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