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2022
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11
Technology of Coal-based Direct Reduction Iron(1)
Keywords:
DRI,RHF
Source: internal company
1. Background Technique
1.1 Basic introduction
At present, there are mainly the following technical routes for direct reduced iron. Coal-based direct reduced iron and gas-based direct reduced iron, among them, gas-based reduction technologies include: COREX, Midrex, FINEX, HIsmelt, etc.Among them, coal-based reduction technologies include: tunnel kiln, RHF, rotary kiln, etc. Gas-based reduction technology can achieve large-volume industrial production. The comprehensive economic indicators are good, but the investment is relatively large. Coal-based reduction technology generally has low output and relatively low investment.
Based on the above reasons and according to the current actual situation, we believe that coal-based reduction technology should be selected first.
1.2 The advantages and disadvantages of several coal-based reduction processes
Process Category |
Advantages |
Disadvantages |
Tunnel kiln |
1. Mature technology |
1. Low degree of automation |
RHF |
1. Mature technology |
1. necessary laboratory research is required for specific raw materials |
Rotary kiln |
1. Mature technology |
1. Need to prepare oxidized pellets first |
Based on the above analysis, we believe that the RHF process should be more suitable.
1.3 Comparison of different direct iron reduction processes
Note: The following information is from a university in China
1.3.1 Comparison of energy consumption of different processes
Process method |
Energy consumption in kind |
Equivalent energy consumption,kgce/t |
Natural gas shaft furnace (HYL-ZR) |
300~350Nm3 Natural gas /t, 10.4~11.5GJ/t |
355.3~392.9 |
Natural gas shaft furnace (MIDREX) |
350~400 Nm3 Natural gas /t, 11.0~12.5 GJ/t |
375.8~427.1 |
Coal to gas - shaft furnace |
600~750kgThermal coal/t, 11.0~12.5 GJ/t |
375.8~427.1 |
Rotary kiln |
850~950kg lignite/t,17.8~21.3GJ/t |
650.0~750.0 |
Tunnel kiln |
250~400kg Burning coal+460~600kg Reduced coal/t |
700.0~800.0 |
1.3.2 Comparison of energy consumption and production capacity of existing main direct reduction processes
Name |
Reducing agent |
Energy consumption (GJ/t) |
Converted standard coal energy consumption (kg/t DRI) |
MIDREX |
Natural gas/ syngas |
11 |
342 |
HYL-Ⅲ |
Natural gas/ syngas |
11 |
342 |
RHF |
coal/Natural gas |
15 |
410 |
SL/RN Rotary kiln |
coal |
18 |
683 |
Tunnel kiln |
coal |
25~30 |
854~1025 |
1.3.3 Productivity index comparison of existing main direct reduction processes
Name |
HYL-Ⅲ shaft furnace |
MIDREX shaft furnace |
SL/RN Rotary kiln |
Tunnel kiln |
RHF |
Pressure of work |
0.8MPa |
0.3 MPa |
-25±15Pa |
|
3000Pa (Air pressure before burner) |
Maximum utilization factor (t/m3d) |
162 |
112 |
0.43 |
|
1.33 |
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