Method for preparing sponge iron by biomass char

Abstract

The invention belongs to the technical field of mineral processing of direct reduction of iron oxide, and relates to a preparation of a biomass char and a method for preparing sponge iron by applying the biomass char to the direct reduction of iron oxide. The main technology comprises steps such as the preparation of the biomass char, the sponge iron preparation by using the biomass char to directly reduce iron oxide, ore grinding, low intensity magnetic separation and the like. The method is characterized by comprising the following steps of: heating biomass such as corn straw, pine sawdust, leaves, waste paper and the like in design equipment at 450-650 DEG C and thermally insulating, obtaining the biomass char and collecting tar, recycling exhaust gas, and using the prepared biomass char as a reducing agent at 1150-1250 DEG C to directly reduce iron oxide to prepare the sponge iron. The grade of the sponge iron reaches more than 90%, and the recovery rate of the sponge iron is more than 85%. The biomass char in the method has the advantages of low N and low S, and can reduce the discharge amount of CO2. The method also has good effects to metallic compounds such as manganese, chromium, vanadium and the like.

Description

technical field

[0001] The invention relates to a preparation of biomass coke and a method for directly reducing iron oxides to produce sponge iron, belonging to the technical field of mineral processing. Background technique

[0002] my country's total iron ore reserves are about 46.232 billion tons (excluding Taiwan Province), accounting for 17.86% of the world's total reserves. There are many lean iron ores and few rich iron ores in my country. The average ore grade is low, and lean ores account for 97.5% of the total reserves. The mined ore needs to be processed by beneficiation, and there are many technical problems in the beneficiation field of poor, fine and miscellaneous iron ore, which affects the use of raw materials in the metallurgical industry.

[0003] At present, the beneficiation processes of magnetic iron ore in my country mainly include stage grinding, fine-grained high-gradient magnetic separation, reverse flotation and other processes. High beneficiation ...

Examples

Embodiment 1

[0025] The corn stalks were crushed to 3-5mm and heated in a self-designed gas circulation electric furnace. The temperature was raised to 500°C and kept at a constant temperature for 50 minutes. The yield of the obtained biomass coke was 28%, the fixed carbon was 70-85%, and the ash content was 1.2%. Collect the tar produced in the preparation of biomass coke and mix it into the next batch of crushed corn stalks for secondary carbonization to achieve full utilization of resources; the waste gas produced in the preparation of biomass coke is recycled in the furnace to reduce energy loss and save costs . Mix sulfuric acid slag with an iron grade of 55% and biomass coke, wherein the ratio of sulfuric acid slag, biomass coke, and flux calcium carbonate is 20:5:4, and put it into a tunnel kiln to heat up to 1150°C after mixing. Keep the temperature for 70 minutes, then cool naturally. Two-stage grinding is adopted, the first-stage grinding fineness is -0.074mm, accounting for 70-...

Embodiment 2

[0027] The pine sawdust was heated in a self-designed gas circulation electric furnace, the temperature was raised to 450°C, and the temperature was kept at a constant temperature for 70 minutes. The yield of the prepared biomass char was 32%, the fixed carbon was 70%, and the ash content was 2.0%. The tar produced in the preparation of biomass coke is collected and mixed into the next batch of pine sawdust for secondary carbonization to achieve full utilization of resources; the waste gas produced in the preparation of biomass coke is recycled in the furnace to reduce energy loss and save costs. Mix limonite with an iron grade of 37% and biomass coke, wherein the ratio of limonite, biomass coke, and flux calcium carbonate is 20:6:3, and put it into a rotary kiln to heat up to 1200 °C after mixing. Keep warm at constant temperature for 50 minutes, then cool naturally. Two-stage grinding is adopted, the first-stage grinding fineness is -0.074mm, accounting for 70-80%, the secon...

Embodiment 3

[0029] The leaves were broken to 3-5mm, heated in a self-designed gas circulation electric furnace, the temperature was raised to 550°C, and the temperature was kept at a constant temperature for 40 minutes. The yield of the prepared biomass char was 27.5%, the fixed carbon was 80.6%, and the ash content was 0.94%. The tar produced in the preparation of biomass coke is collected and mixed into the next batch of broken leaves for secondary carbonization to realize full utilization of resources; the waste gas produced in the preparation of biomass coke is recycled in the furnace to reduce energy loss and save costs. Mix the specularite with an iron grade of 35% and biomass coke, wherein the ratio of specularite, biomass coke, and flux calcium carbonate is 20:4:3, and put it into a fluidized bed to heat up to 1200°C after mixing , kept at a constant temperature for 55 minutes, used waste gas from the preparation of biomass coke as reducing gas, and then cooled naturally. Two-stag...

technical field

[0001] The invention relates to a preparation of biomass coke and a method for directly reducing iron oxides to produce sponge iron, belonging to the technical field of mineral processing. Background technique

[0002] my country's total iron ore reserves are about 46.232 billion tons (excluding Taiwan Province), accounting for 17.86% of the world's total reserves. There are many lean iron ores and few rich iron ores in my country. The average ore grade is low, and lean ores account for 97.5% of the total reserves. The mined ore needs to be processed by beneficiation, and there are many technical problems in the beneficiation field of poor, fine and miscellaneous iron ore, which affects the use of raw materials in the metallurgical industry.

[0003] At present, the beneficiation processes of magnetic iron ore in my country mainly include stage grinding, fine-grained high-gradient magnetic separation, reverse flotation and other processes. High beneficiation ...

Examples

Embodiment 1

[0025] The corn stalks were crushed to 3-5mm and heated in a self-designed gas circulation electric furnace. The temperature was raised to 500°C and kept at a constant temperature for 50 minutes. The yield of the obtained biomass coke was 28%, the fixed carbon was 70-85%, and the ash content was 1.2%. Collect the tar produced in the preparation of biomass coke and mix it into the next batch of crushed corn stalks for secondary carbonization to achieve full utilization of resources; the waste gas produced in the preparation of biomass coke is recycled in the furnace to reduce energy loss and save costs . Mix sulfuric acid slag with an iron grade of 55% and biomass coke, wherein the ratio of sulfuric acid slag, biomass coke, and flux calcium carbonate is 20:5:4, and put it into a tunnel kiln to heat up to 1150°C after mixing. Keep the temperature for 70 minutes, then cool naturally. Two-stage grinding is adopted, the first-stage grinding fineness is -0.074mm, accounting for 70-...

Embodiment 2

[0027] The pine sawdust was heated in a self-designed gas circulation electric furnace, the temperature was raised to 450°C, and the temperature was kept at a constant temperature for 70 minutes. The yield of the prepared biomass char was 32%, the fixed carbon was 70%, and the ash content was 2.0%. The tar produced in the preparation of biomass coke is collected and mixed into the next batch of pine sawdust for secondary carbonization to achieve full utilization of resources; the waste gas produced in the preparation of biomass coke is recycled in the furnace to reduce energy loss and save costs. Mix limonite with an iron grade of 37% and biomass coke, wherein the ratio of limonite, biomass coke, and flux calcium carbonate is 20:6:3, and put it into a rotary kiln to heat up to 1200 °C after mixing. Keep warm at constant temperature for 50 minutes, then cool naturally. Two-stage grinding is adopted, the first-stage grinding fineness is -0.074mm, accounting for 70-80%, the secon...

Embodiment 3

[0029] The leaves were broken to 3-5mm, heated in a self-designed gas circulation electric furnace, the temperature was raised to 550°C, and the temperature was kept at a constant temperature for 40 minutes. The yield of the prepared biomass char was 27.5%, the fixed carbon was 80.6%, and the ash content was 0.94%. The tar produced in the preparation of biomass coke is collected and mixed into the next batch of broken leaves for secondary carbonization to realize full utilization of resources; the waste gas produced in the preparation of biomass coke is recycled in the furnace to reduce energy loss and save costs. Mix the specularite with an iron grade of 35% and biomass coke, wherein the ratio of specularite, biomass coke, and flux calcium carbonate is 20:4:3, and put it into a fluidized bed to heat up to 1200°C after mixing , kept at a constant temperature for 55 minutes, used waste gas from the preparation of biomass coke as reducing gas, and then cooled naturally. Two-stag...

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