CN-115852076-B - Device and method for improving graphite precipitation amount in molten iron

CN115852076BCN 115852076 BCN115852076 BCN 115852076BCN-115852076-B

Abstract

The invention relates to the field of comprehensive utilization of resources, in particular to a device and a method for improving graphite precipitation in molten iron. The device comprises a blast furnace molten iron channel, wherein a plurality of injection pipelines are arranged at the bottom of the blast furnace molten iron channel, and the other ends of the injection pipelines are connected with a pulverized coal feeding system through conveying pipelines. The method comprises the steps of injecting pulverized coal into a molten iron runner of a blast furnace through an injection pipeline to improve the carbon content in molten iron, cooling along with the molten iron, supersaturating carbon in the molten iron, and precipitating graphite. The invention sprays coal powder into the molten iron channel, utilizes the stirring kinetic energy generated by higher molten iron temperature and molten iron flow to promote the coal powder to be quickly and efficiently dissolved, increases the carbon content in the molten iron, adopts the proper blast furnace molten iron cooling speed, obviously improves the precipitation proportion of the subsequent graphite under the same condition, finally precipitates the carbon sprayed into the molten iron in the form of the coal powder in the form of the graphite, greatly improves the added value of ferrous metallurgy, has obvious economic benefit and also has obvious influence on the development of new graphite resources.

Inventors

WANG NIANXIN
YUAN YUHAO
ZENG HUI
WANG YUMIN
WANG XING
CHEN WANFU
SUN ZONGHUI
ZHANG GE
LUAN JIYI
DONG HONGZHUANG

Assignees

山东钢铁股份有限公司

Dates

Publication Date: 20260505
Application Date: 20221101

Claims (1)

1. A method for improving graphite precipitation amount in molten iron is characterized by using a device for implementing the method, wherein the device comprises a blast furnace molten iron channel, a plurality of injection pipelines are arranged at the bottom of the blast furnace molten iron channel, and the other ends of the injection pipelines are connected with a pulverized coal feeding system through conveying pipelines; The pulverized coal feeding system comprises a coal bunker, the output end of the coal bin is communicated with a carrier gas source; the length direction of the injection pipeline and the length direction of the blast furnace molten iron runner form an acute angle, and the inclination angle of the injection pipeline is consistent with the flowing direction of molten iron in the blast furnace molten iron runner; the injection pipeline is made of magnesium high-temperature resistant material, the diameter of the injection pipeline is 8mm, and the interval between adjacent injection pipelines is 1-1.5m; The diameter of the conveying pipeline is 80-100mm; The method comprises the steps of injecting pulverized coal into a molten iron runner of a blast furnace to improve carbon content in molten iron, cooling the molten iron, supersaturating carbon in the molten iron, precipitating graphite, conveying the pulverized coal by adopting nitrogen as carrier gas, wherein the flow rate of the nitrogen is 2000-3500Nm 3 /h, the pressure is 1.1-1.2MPa, the particle size of the pulverized coal is 1-2mm, the dosage is 1-1.5kg/min, the temperature of the molten iron discharged from the blast furnace is 1520 ℃ when the pulverized coal is injected, the carbon content of the molten iron is higher than 4.3% after the pulverized coal is injected, the cooling mode of the molten iron is air cooling, and the cooling speed of the molten iron is 0.5-50 ℃.

Description

Device and method for improving graphite precipitation amount in molten iron Technical Field The invention relates to the field of comprehensive utilization of resources, in particular to a device and a method for improving graphite precipitation in molten iron. Background Graphite is a nonmetallic mineral resource, and a large amount of large scale graphite can be produced in the production process of ferrous metallurgy industry in China. The carbon-containing molten iron of the blast furnace can cause supersaturation of carbon elements in the molten iron due to temperature change of the molten iron to separate out aggregated large-scale graphite, and the aggregated large-scale graphite has the same performance as natural large-scale graphite after being collected and purified. However, at present, the problem of graphite precipitation is basically not considered in the ferrous metallurgy industry, so that the amount of graphite precipitation in molten iron is small, and the economic benefit is low. Disclosure of Invention Aiming at the technical problem of lower graphite precipitation amount in molten iron in the prior art, the invention provides a device and a method for improving the graphite precipitation amount in molten iron, and the recovery ratio of graphite is improved by utilizing the principle that the higher the carbon content of molten iron is, the earlier the graphite precipitation is and the more the precipitation ratio is. In a first aspect, the invention provides a device for improving graphite precipitation in molten iron, which comprises a blast furnace molten iron channel, wherein a plurality of injection pipelines are arranged at the bottom of the blast furnace molten iron channel, and the other ends of the injection pipelines are connected with a pulverized coal feeding system through conveying pipelines. Further, the pulverized coal feeding system comprises a coal bunker, and the output end of the coal bunker is communicated with a carrier gas source. Further, the length direction of the injection pipeline is an acute angle with the length direction of the blast furnace molten iron runner, the inclination angle of the injection pipeline is consistent with the flowing direction of molten iron in the blast furnace molten iron runner, the injection pipeline is made of magnesia high-temperature resistant materials, the diameter of the injection pipeline is 8mm, and the interval between adjacent injection pipelines is 1-1.5m. Further, the diameter of the conveying pipeline is 80-100mm. In a second aspect, the present invention provides a method for increasing the graphite precipitation amount in molten iron, wherein pulverized coal is injected into a molten iron runner of a blast furnace to increase the carbon content in the molten iron, and then the molten iron is cooled, so that carbon in the molten iron is supersaturated and graphite is precipitated. Further, the coal dust is conveyed by adopting nitrogen as carrier gas, the flow rate of the nitrogen is 2000-3500Nm 3/h, and the pressure is 1.1-1.2MPa. Further, the grain diameter of the pulverized coal is 1-2mm, and the dosage is 1-1.5kg/min. Further, the temperature of the molten iron discharged from the blast furnace when pulverized coal is injected is 1520 ℃. Further, after pulverized coal is injected, the carbon content of molten iron is higher than 4.3%. Further, the cooling mode of the molten iron is air cooling, such as transferring and radiating cooling, and the cooling speed of the molten iron is 0.5-50 ℃ per minute. The quantity and the geometric dimension of the plate graphite are influenced by the cooling speed of molten iron, when the cooling speed is higher than 50 ℃ per minute, the quantity of the plate graphite is smaller, the geometric dimension is smaller, the quantity of the plate graphite is larger due to the slower cooling speed, and the geometric dimension is relatively larger, so that the proper cooling speed (0.5-50 ℃ per minute) is a sufficient condition for the mass precipitation of the plate graphite. The invention has the beneficial effects that: The invention sprays coal powder into the molten iron channel, and utilizes the stirring kinetic energy generated by the higher molten iron temperature and the molten iron flow to promote the rapid and efficient dissolution of the sprayed coal powder, increases the carbon content in the molten iron, adopts the proper blast furnace molten iron cooling speed, obviously improves the precipitation proportion of the subsequent graphite under the same condition, finally precipitates the carbon sprayed into the molten iron in the form of the coal powder in the form of graphite, greatly improves the added value of ferrous metallurgy, has obvious economic benefit, and has obvious influence on the recovery and high-valued application of byproducts in the steel industry and the development of the emerging graphite resources. Drawings In order to more clearly illustrate the embo