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Method for recycling gas-base direct reducted tail gas

A direct technology of tail gas recovery, applied in the direction of fluidized bed furnace, etc., can solve the problems of heat loss, affecting natural gas conversion, catalyst poisoning, etc., to achieve the effect of reducing reduction temperature, efficient utilization, and speeding up the reduction process

Inactive Publication Date: 2013-01-09
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, after the furnace top gas is washed and purified, on the one hand, it causes a large amount of heat loss, and on the other hand, the harmful components remaining in the gas that are difficult to remove completely accumulate gradually with the increase of the number of cycles, thus affecting the conversion of natural gas (catalyst poisoning) ) and the normal operation of the shaft furnace

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] Example 1: Take 100g of oxidized pellets (12mm ~ 16mm) and put them into the reduction shaft furnace. 2 , 20%CO 2 , 10%N 2 (Volume percent) After reduction for 30 minutes under the condition, the reduction rate of the obtained pre-reduced pellets was 40.31%, and the amount of carbon precipitation was 5.82% of the total mass. The obtained pre-reduced pellets were mixed with 10% of the total mass of the mixture, and then placed in a microwave oven for reduction (power 1.5kW), the temperature was 1000°C, and the required time was 37 minutes. At this time, the metallization rate of the pellets was 95.34 %, the average compressive strength is 1725N / piece. Compared with Comparative Examples 1 and 2, it can be seen that the heating time in the microwave oven is shortened by nearly half, the metallization rate is 12% to 18% higher than that of the carbon-free pellets, and the compressive strength of the pellets is increased by more than 700N. Compared with the air-based redu...

Embodiment 2

[0036] Example 2: Take 100g of oxidized pellets (8mm ~ 12mm) and put them into the reduction shaft furnace. 2 , 10%CO 2 , 10%H 2 O, 10%N 2 (Volume percent) After reduction for 60 minutes under the condition, the reduction rate of the obtained pre-reduced pellets was 42.01%, and the amount of carbon precipitation was 5.56% of the total mass. The obtained pre-reduced pellets were mixed with 8% coal powder accounting for the total mass of the mixture, and then placed in a microwave oven for reduction (power 1.5kW), the temperature was 1000°C, and the required time was 36min. %, the average compressive strength is 1885N / piece. Compared with Comparative Examples 1 and 2, it can be seen that the heating time in the microwave oven is shortened by nearly half, the metallization rate is 14%-20% higher than that of the carbon-free pellets, and the compressive strength of the pellets is increased by more than 800N. Compared with the air-based reduction of Comparative Example 3, the m...

Embodiment 3

[0038] Take 100g of oxidized pellets (12mm ~ 16mm) and put them into the reduction shaft furnace. 2 , 10%N 2(Volume percentage) After being treated for 60 minutes under the condition, the reduction rate of the obtained pre-reduced pellets was 28.98%, and the amount of carbon precipitation was 4.62% of the total mass. The obtained pre-reduced pellets were mixed with anthracite coal accounting for 15% of the total mass of the mixture, and then placed in a microwave oven for reduction (power 1.5kW), the temperature was 1000°C, and the required time was 39 minutes. At this time, the metallization rate of the pellets was 93.21%. , the average compressive strength is 1522N / piece. Compared with Comparative Examples 1 and 2, it can be seen that the heating time in the microwave oven is shortened by nearly half, the metallization rate is 10%-15% higher than that of the carbon-free pellets, and the compressive strength of the pellets is increased by about 500N. Compared with the air-b...

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Abstract

The invention discloses a method for recycling gas-base direct reduced tail gas. Firstly the gas-base direct reduced tail gas is used for conducting pre-heating and pre-reduction treatment on iron ore pellets, CO in the tail gas has a reaction that two COs are reacted to generate CO2 and C in the above treatment process, separated carbon black is deposited in holes and on surfaces of pre-reduced pellets where gaps are rich, and the pre-reduced pellets containing fine carbon black are formed. The pre-reduced carbon separated pellets are mixed with certain quantity of a reducing agent, and then added into an industrial microwave oven to conduct deep reduction, and then magnetic separating is carried out to obtain direct reduced iron. The method can effectively use tail gas in traditional gas-base direct reduction process and secondary heat reducing gas produced in a metallurgy process to conduct prereduction and carbon separation, and use high-efficient and rapid characteristics of microwave heating and excellent absorbing properties of carbon black to conduct direct reduction on the iron ore pellets so as to achieve a purpose of energy conservation and environmental protection production.

Description

technical field [0001] The invention relates to a tail gas recovery and utilization method, in particular to a method for producing sponge iron by using direct reduction tail gas carbonization-microwave heating reduction. Background technique [0002] Due to its pure texture and stable composition, direct reduced iron (DRI) is an ideal raw material for replacing scrap steel, smelting high-quality steel and special steel. Many special steels that cannot be produced with scrap steel can be produced with sponge iron. In recent years, with the rise of the "short process of electric furnace steelmaking", direct reduced iron, which is a substitute for scrap steel and an indispensable raw material for the production of high-quality special steel, has developed rapidly. At present, more than 75% of the world's direct reduced iron is produced by the gas-based shaft furnace method, of which the typical processes are Midrex and HYL-Ⅲ method (accounting for 59.7% and 14.1% of direct red...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21B13/00
Inventor 黄柱成姜涛易凌云张元波郭宇峰李光辉杨永斌
Owner CENT SOUTH UNIV
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