CN109929957B - Device and method for producing molten iron by high-temperature smelting of pre-reduced iron ore - Google Patents
Device and method for producing molten iron by high-temperature smelting of pre-reduced iron ore Download PDFInfo
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Abstract
A device and a method for producing molten iron by high-temperature smelting of pre-reduced iron ore, wherein the device comprises a furnace body, an electrode and a coal-fired spray gun, and a raw material conveying pipeline is inserted into the furnace body; the upper layer space is provided with a high-temperature flue gas outlet, an electrode and a coal-fired spray gun, the bottom end of the electrode is positioned in the slag layer area, a slag discharging port is positioned in the slag layer space, and a molten iron outlet is communicated with the molten iron layer area; the method comprises the following steps: (1) mixing and conveying pre-reduced iron ore and a flux into a device, (2) starting a power supply and spraying coal powder, and melting the pre-reduced iron ore and the flux to form a melt; (3) iron oxide reacts with coal powder to generate molten iron and slag, and the molten iron is further heated by electric arc generated by the molten iron; (4) and when the smelting is carried out, the temperature is 1350-1550 ℃, after the smelting is finished, the slag discharging port is opened to discharge slag, and then the molten iron outlet is opened to discharge molten iron. The method realizes the synergistic utilization of energy consumption, greatly reduces the loss of energy consumption and improves the utilization efficiency of energy.
Description
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to a device and a method for producing molten iron by smelting pre-reduced iron ore at a high temperature.
Background
At present, blast furnace ironmaking, namely, coke, iron-containing ore (natural rich lump ore, sinter ore or pellet ore) and flux (limestone and dolomite) are adopted to continuously produce liquid pig iron in a vertical reactor-blast furnace, which is a main method for modern ironmaking, the output of the method accounts for more than 95 percent of the total output of the pig iron in the world, and the environmental pollution problem caused by coke production is still in a deepening state continuously; in order to solve the problem, related personnel should increase the research and application of non-blast furnace ironmaking technology so as to improve the industrial structure of the development of the steel industry in China.
Non-blast furnace ironmaking is different from blast furnace ironmaking, and has certain advantages in energy consumption; particularly, the non-blast furnace ironmaking can greatly reduce the usage amount of coking coal, so that the pollutant discharge amount generated by high-furnace ironmaking processes such as pelletizing, sintering and coking processes is reduced; the HIsmelt process is a typical non-blast furnace ironmaking method, and the method adopts a smelting reduction furnace (SRV furnace) to carry out smelting reduction on pre-reduced iron ores to obtain qualified molten iron; however, the smelting reduction furnace has a large coal consumption, so that the research and development of novel low-consumption non-blast furnace ironmaking technology and equipment are urgently needed.
Disclosure of Invention
The invention aims to provide a device and a method for producing molten iron by smelting pre-reduced iron ore at high temperature, which synchronously realize the smelting reduction of iron ore and the smelting and layering separation of ore by adopting a special smelting device to smelt the pre-reduced iron ore, synergistically utilize electric energy and coal energy and reduce the production cost.
The device for producing molten iron by smelting the pre-reduced iron ore at high temperature comprises a furnace body, electrodes and a coal-fired spray gun, wherein a raw material conveying pipeline is inserted into the furnace body; the furnace body is internally provided with an upper space, a slag layer area and a molten iron layer area from top to bottom in sequence, the upper space is provided with a high-temperature flue gas outlet, an electrode and a coal-fired spray gun, the bottom end of the electrode is positioned in the slag layer area, the outlet of the coal-fired spray gun and the outlet of a raw material conveying pipeline are positioned in the upper space, a slag discharging port is positioned in the slag layer space, and the molten iron outlet is communicated with the molten iron layer area.
The method for producing molten iron by smelting the pre-reduced iron ore at high temperature adopts the device and comprises the following steps:
1. uniformly mixing the pre-reduced iron ore and the flux, and conveying the mixture to a device for producing molten iron by high-temperature smelting of the pre-reduced iron ore through a pipeline, wherein the iron grade TFe of the pre-reduced iron ore is not less than 55%, the MFe mass percentage is 35-60%, and the granularity is not more than 12 mm; the flux is limestone and/or calcium oxide, the addition amount of the flux is 1.00-2.30 according to the alkalinity of the mixture of the pre-reduced iron ore and the flux, and the alkalinity is CaO + MgO and SiO2+Al2O3The mass ratio of (a);
2. starting a three-phase power supply connected with the electrode, simultaneously spraying coal powder by taking air as carrier gas through a coal-fired spray gun, and melting the pre-reduced iron ore and the flux by means of electrode heating and coal powder combustion in the device to form a melt;
3. in the smelting process of the melt, iron oxide in the slag reacts with the pulverized coal to generate molten iron and form slag, the molten iron sinks to the bottom of the device under the action of gravity and density difference, and the molten slag floats above the molten iron; after the molten iron is formed, electric arcs are generated between the electrodes through the molten iron to further heat the molten iron and the molten slag;
4. when smelting is carried out, the time from the time when the pre-reduced iron ore enters the device to the time when the pre-reduced iron ore is melted is controlled to be 1.5-2.5 h, the temperature in the device is 1350-1550 ℃, and finally the molten iron is filled in the molten iron layer space; and after the smelting is finished, opening a slag discharge port to discharge slag, and then opening a molten iron outlet to discharge molten iron.
The TFe of the molten iron obtained by the method is more than or equal to 90 percent.
The mass content of the fixed carbon in the coal powder adopted by the method is more than or equal to 60 percent, and the granularity of the coal powder is less than or equal to 1 mm.
In the method, the injection amount of the pulverized coal is 50-300 kg/t according to the coal ratio (the mass ratio of the pulverized coal to the pre-reduced iron ore).
The principle of the invention is as follows: after the pre-reduced iron ore is heated by an electrode and is combusted, heated and melted by pulverized coal, the melting reduction and the liquid iron slag layer separation are synchronously realized; the material heating mode adopts the uniquely designed electric arc heating and is assisted with the spray gun coal-fired heating, so that the energy is utilized cooperatively, the energy consumption loss is greatly reduced, and the energy utilization efficiency is improved.
Drawings
FIG. 1 is a schematic view showing the construction of an apparatus for manufacturing molten iron by high-temperature smelting of pre-reduced iron ore according to the present invention;
in the figure, 1, an electrode, 2, a coal-fired spray gun, 3, slag, 4, a molten iron outlet, 5, molten iron, 6, a slag discharge port, 7, a raw material conveying pipeline, 8, a high-temperature flue gas outlet, 9 and a furnace body.
Detailed Description
The pre-reduced iron ore in the embodiment of the invention is generated by directly reducing iron ore through a rotary kiln or a tunnel kiln.
In the embodiment of the invention, the part with the granularity of-0.074 mm in the coal powder accounts for 40-60% of the total mass of the coal powder.
The pre-reduced iron ore in the embodiment of the invention is pellet ore, the iron grade TFe is not less than 55 percent, MFe is 35-60 percent, and SiO is contained according to the mass percentage23～8％，Al2O33～8％，CaO 0.1～1.5％，MgO 1～11％，P≤0.1％，S≤0.05％。
The molten iron in the embodiment of the invention contains 93-96% of Fe, 3.5-4.2% of C, less than or equal to 0.04% of P, less than or equal to 0.02% of S, less than or equal to 0.5% of Si and less than or equal to 0.05% of Al in percentage by mass.
The coal powder adopted in the embodiment of the invention contains 60-78% of fixed carbon by weight percent, and the part with the granularity of-0.074 mm accounts for 40-60% of the total weight.
The metallization rate of the pellet in the embodiment of the invention is 70-85%.
The following are preferred embodiments of the present invention.
Example 1
The structure of the device for producing molten iron by smelting pre-reduced iron ore at high temperature is shown in figure 1, and comprises a furnace body 9, an electrode 1 and a coal-fired spray gun 2; the raw material conveying pipeline 7 is inserted into the furnace body; an upper layer space, a slag layer area and a molten iron layer area are sequentially arranged in the furnace body 9 from top to bottom, the upper layer space is provided with a high-temperature flue gas outlet 8, an electrode 1 and a coal-fired spray gun 2, the bottom end of the electrode 1 is positioned in the slag layer area, an outlet of the coal-fired spray gun 2 and an outlet of a raw material conveying pipeline 7 are positioned in the upper layer space, a slag discharge port 6 is positioned in the slag layer space, and a molten iron outlet 4 is communicated with the molten iron layer area;
the pellet ore of certain pre-reduced iron ore is adopted and comprises TFe 55.62%, MFe 38.93% and SiO in percentage by weight23.01％，Al2O37.28 percent of CaO, 0.10 percent of CaO, 10.2 percent of MgO, 0.08 percent of P, 0.03 percent of S and the granularity of less than or equal to 12 mm;
the adopted reducing agent coal dust contains 60 percent of fixed carbon by weight percent, and the part with the granularity of 0.074mm accounts for 40 percent of the total weight;
uniformly mixing the pre-reduced iron ore and a flux, and conveying the mixture to a device for producing molten iron by high-temperature smelting of the pre-reduced iron ore through a pipeline, wherein the flux is limestone and/or calcium oxide, and the addition amount of the flux is 1.00 according to the alkalinity of the mixed pre-reduced iron ore and flux;
starting a three-phase power supply connected with the electrode, simultaneously spraying coal powder by taking air as carrier gas through a coal-fired spray gun, and melting the pre-reduced iron ore and the flux by means of electrode heating and coal powder combustion in the device to form a melt; the blowing amount of the pulverized coal is 100kg/t according to the coal ratio
In the smelting process of the melt, iron oxide in the slag reacts with the pulverized coal to generate molten iron, the rest of the molten iron forms slag, the molten iron sinks to the bottom of the device under the action of gravity and density difference, and the molten slag floats above the molten iron; after the molten iron forms, electric arcs are generated between the electrodes through the molten iron to further heat the molten iron and the slag;
when smelting is carried out, the time from the time when the pre-reduced iron ore enters the device to the time when the pre-reduced iron ore is melted is controlled to be 2.5h, the temperature in the device is 1350 ℃, and finally the molten iron layer space is filled with the molten iron; after the smelting is finished, opening a slag discharge port to discharge slag, and then opening a molten iron outlet to discharge molten iron;
the obtained molten iron contains 93% of Fe, 3.5% of C, 0.04% of P, 0.02% of S, 0.5% of Si and 0.05% of AlC by mass percent.
Example 2
Pellets of a pre-reduced iron ore powder comprising, by weight, TFe 57.73%, MFe 46.18%, SiO27.55％，Al2O33.42 percent of CaO, 1.32 percent of MgO, 2.36 percent of P, 0.09 percent of S and the granularity of less than or equal to 12 mm;
the reducing agent coal dust contains 78 percent of fixed carbon by weight, and the part with the granularity of 0.074mm accounts for 40 percent of the total weight;
the device structure is the same as that of embodiment 1; the method is the same as example 1, except that:
(1) the adding amount of the flux is 1.80 according to the alkalinity of the pre-reduced iron ore and the flux after mixing;
(2) the blowing amount of the coal powder is 200kg/t according to the coal ratio;
(3) controlling the time from the time of entering the device to the time of melting the pre-reduced iron ore to be 1.5h, and controlling the temperature in the device to be 1550 ℃;
the obtained molten iron contains 93% of Fe, 4.2% of C, 0.03% of P, 0.01% of S, 0.4% of Si and 0.04% of AlO by mass percent.
Example 3
Pellets of certain pre-reduced powdered iron ore are adopted and comprise, by weight, 62.83% of TFe, 50.55% of MFe and SiO23.53％，Al2O37.81％，CaO 0.10％，MgO 1.22％，P 0.09％，S 0.04％
The adopted reducing agent coal dust contains 63 percent of fixed carbon by weight percent, and the granularity of-0.074 mm accounts for 60 percent;
the device structure is the same as that of embodiment 1; the method is the same as example 1, except that:
(1) the adding amount of the flux is 2.30 according to the alkalinity of the pre-reduced iron ore and the flux after mixing;
(2) the blowing amount of the coal powder is 300kg/t according to the coal ratio;
(3) controlling the time from the time of entering the device to the time of melting the pre-reduced iron ore to be 2 hours, and controlling the temperature in the device to be 1400 ℃;
the obtained molten iron contains 96 percent of Fe, 3.5 percent of C, 0.04 percent of P, 0.01 percent of S, 0.3 percent of Si and 0.03 percent of All according to mass percentage.
Example 4
The pellet of pre-reduced powdered iron ore contains TFe 65.67 wt%, MFe 55.82 wt% and SiO24.21％，Al2O32.36％，CaO 0.10％，MgO 0.16％，P 0.09％，S 0.04％
The adopted reducing agent coal dust contains 78 percent of fixed carbon by weight percent, and the granularity of-0.074 mm accounts for 55 percent;
the device structure is the same as that of embodiment 1; the method is the same as example 1, except that:
(1) the adding amount of the flux is 1.50 according to the alkalinity of the pre-reduced iron ore and the flux after mixing;
(2) the blowing amount of the coal powder is 150kg/t according to the coal ratio;
(3) controlling the time from the time of entering the device to the time of melting the pre-reduced iron ore to be 1.5h, and controlling the temperature in the device to be 1500 ℃;
the obtained molten iron contains, by mass, 94% of Fe, 4.1% of C, 0.03% of P, 0.02% of S, 0.5% of Si and 0.04% of Al.
Claims (1)
1. A method for producing molten iron by smelting pre-reduced iron ore at high temperature is characterized in that a device for producing molten iron by smelting pre-reduced iron ore at high temperature is adopted, the device comprises a furnace body, electrodes and a coal-fired spray gun, and a raw material conveying pipeline is inserted into the furnace body; the furnace body is internally provided with an upper space, a slag layer area and a molten iron layer area from top to bottom in sequence, the upper space is provided with a high-temperature flue gas outlet, an electrode and a coal-fired spray gun, the bottom end of the electrode is positioned in the slag layer area, the outlet of the coal-fired spray gun and the outlet of a raw material conveying pipeline are positioned in the upper space, a slag discharge port is positioned in the slag layer space, and the molten iron outlet is communicated with the molten iron layer area;
the method comprises the following steps:
(1) uniformly mixing pre-reduced iron ore and flux, and conveying the mixture to a device for producing molten iron by smelting the pre-reduced iron ore at high temperature through a pipeline, wherein the pre-reduced iron ore contains 55.62-65.67% of iron grade TFe and 35-60% of MFe according to mass percentage and contains SiO23～8%，Al2O33-8%, CaO 0.1-1.5%, MgO 1-11%, P is less than or equal to 0.1%, S is less than or equal to 0.05%, and granularity is less than or equal to 12 mm; the flux is limestone and/or calcium oxide, the addition amount of the flux is 1.00-2.30 according to the alkalinity of the mixture of the pre-reduced iron ore and the flux, and the alkalinity is CaO + MgO and SiO2+Al2O3The mass ratio of (a);
(2) starting a three-phase power supply connected with the electrode, simultaneously spraying coal powder by taking air as carrier gas through a coal-fired spray gun, and melting the pre-reduced iron ore and the flux by means of electrode heating and coal powder combustion in the device to form a melt; the pulverized coal contains 60-78% of fixed carbon by weight percent, and the part with the granularity of-0.074 mm accounts for 40-60% of the total weight; the injection amount of the pulverized coal is 50-300 kg/t according to the coal ratio;
(3) in the smelting process of the melt, iron oxide in the slag reacts with the pulverized coal to generate molten iron and form slag, the molten iron sinks to the bottom of the device under the action of gravity and density difference, and the molten slag floats above the molten iron; after the molten iron is formed, electric arcs are generated between the electrodes through the molten iron to further heat the molten iron and the molten slag;
(4) when smelting is carried out, the time from the time when the pre-reduced iron ore enters the device to the time when the pre-reduced iron ore is melted is controlled to be 1.5-2.5 h, the temperature in the device is 1350-1550 ℃, and finally the molten iron is filled in the molten iron layer space; after the smelting is finished, opening a slag discharge port to discharge slag, and then opening a molten iron outlet to discharge molten iron; the molten iron contains 93-96% of Fe, 3.5-4.2% of C, less than or equal to 0.04% of P, less than or equal to 0.02% of S, less than or equal to 0.5% of Si and less than or equal to 0.05% of Al in percentage by mass.
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