What are the main inputs for producing 1 ton of cast iron in a blast furnace?
1.5 - 1.8 tons of iron ores (lumps, sinters, or pellets), 0.5 tons of coke, and 0.15 tons of flux (limestone or dolomite).
How can one calculate the Enthalphy change from the heat capacity?
multiplied by the amount of mols
for a linear change:
ΔH = m * C * ΔT
with c being the heat capacity
What is the role of coke in a blast furnace?
Coke serves as a source of heat (through combustion) and as a reducing agent (producing CO), and it sustains the furnace structure.
What is the purpose of a 'moist blast' in a blast furnace?
It involves pre-heating air in a cowper at 900 - 1260°C under 3 - 4 atm pressure, possibly with oxygen enrichment, to improve the furnace's efficiency.
Moisture is added for temeperature control, gasificaion aid for the carbon and reduced dust emissions.
What is the typical composition of pig iron produced in a blast furnace?
Approximately 3-4% carbon, 3-4% manganese, 1-2% silicon, 0.1% phosphorus, and 0.05% sulfur.
What is the typical output of slag per ton of cast iron produced?
Approximately 290 kg of slag per ton of cast iron.
What are 'Cowpers' in a blast furnace?
Cowpers, or regenerative 'hot blast stoves', pre-heat the air for the blast furnace to increase efficiency.
How is the reaction volume in a blast furnace calculated?
Based on the daily production and the unit material volume required for producing 1 ton of pig iron.
P=daily production
t=retention time (dependant on the reduceability)
v=unit material volume (around 2m^3)
What factors influence the retention time of materials in a blast furnace?
The reducibility of the ores, which typically ranges around 4 - 6 hours.
What are the key chemical reactions in a blast furnace?
Combustion (C + O2 → CO2), reduction with CO (CO2 + C → 2CO), and reduction of various oxides (e.g., MnO, SiO2) with carbon. The reduction of iron oxides.
What is the 'Boudouard reaction' in the context of a blast furnace?
The reaction 2CO ↔ C + CO2, which is important in the internal gas balance and reduction processes.
What are the main components of the top gas in a blast furnace and their amount per ton of pig iron?
Approximately 25% CO, with a volume of 1500-1600 Nm3 per ton of pig iron.
How high is the approximate heat loss?
7-15 %
How is the amount of coke determined for a blast furnace operation?
Based on the desired production of cast iron, quality of iron ores, and other process parameters.
What is the significance of oxygen enrichment in a blast furnace?
It controls the temperature and improves the efficiency of the reduction reactions.
What are the current trends in reducing slag production in blast furnaces?
Using autofluxing minerals
How has the use of sinter changed in modern blast furnace operations?
There's a tendency to use more than 90% of sinter due to its better size distribution and autofluxing properties.
What are the alternate fuels used in blast furnaces to reduce coke consumption?
Less expensive fuels like fuel oils are being increasingly used.
How is the temperature controlled in a blast furnace?
Through control of oxygen enrichment, typically up to 20%.
What is the significance of the mass and heat balance in a blast furnace?
It helps in optimizing the inputs (ores, coke, flux) and understanding the furnace efficiency.
Describe the temperature distribution in a blast furnace.
Describe the heat balance of the blast furnace.
What is the purpose of tuyeres in a blast furnace?
Tuyeres inject the hot air (blast) into the furnace, aiding combustion and the reduction process.
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