# Reduction in the blast furnace

> Coke makes the gas that takes the oxygen


## Objectives

- Write the three blast furnace equations with their conditions.
- Identify carbon monoxide as the reducing agent of the ore.
- Explain the role of coke in the blast furnace.

## 1. Iron ores and extraction of iron




## 2. Who takes the oxygen?

Predict: in the book's equations, what takes the oxygen from $\ce{Fe2O3}$?

- Carbon dioxide, $\ce{CO2}$
- Carbon monoxide, CO, made from the coke ✓
- Oxygen from the air
- Solid coke, directly

Carbon monoxide, CO, made from the coke, takes the oxygen: $\ce{3CO + Fe2O3 -> 2Fe + 3CO2}$ above 700 °C. In $\ce{CO2}$ carbon already holds two oxygen atoms, and oxygen from the air would add oxygen instead of removing it.

[ar-EG] الـ carbon monoxide، يعني CO، اللي بيتكوّن من الـ coke، هو اللي بياخد الـ oxygen: $\ce{3CO + Fe2O3 -> 2Fe + 3CO2}$ عند أعلى من 700 °C. في الـ $\ce{CO2}$ الـ carbon شايل خلاص ذرتين oxygen، والـ oxygen اللي في الهوا هيزوّد oxygen بدل ما يشيله.
## 3. Reduction of iron ores

Extraction of iron from its ores: three stages (book p.17-18) Reduction of iron ores The reduction of iron oxides to iron, by one of two methods depending on the reducing agent. Method (a): carbon monoxide from coke, in the blast furnace. Method (b), the Midrex furnace, comes next.


## 4. Coke makes carbon monoxide

Coke A solid fuel made from coal. It is mostly carbon. Coke burns to $\ce{CO2}$. The $\ce{CO2}$ meets more hot coke and becomes CO.


## 5. CO reduces the ore

The book's condition: higher than 700 °C.


## 6. Why 3 CO?

Each CO takes one oxygen atom. Add CO molecules to one $\ce{Fe2O3}$. CO molecules O removed O still on the iron Exactly enough: all 3 O atoms removed. You get 2Fe + 3CO₂. One CO is left over: $\ce{Fe2O3}$ has only 3 O atoms. Now balance it yourself.


## 7. Coke or CO?

Coke itself reduces the ore. Coke is the source; CO takes the oxygen Contrast: $\ce{CO2}$ is not a reducing agent here. Its carbon has already gained all the oxygen it takes in these reactions. Role of coke: a fuel, and the source of carbon monoxide, the reducing agent.


## 8. Check yourself

Exam question: "Explain the role of coke in the blast furnace." Which answer gets full marks?

- It reduces $\ce{Fe2O3}$ directly to iron.
- It removes sulphur and phosphorus from the ore.
- It burns to $\ce{CO2}$; with more coke this gives CO, which reduces the ore. ✓
- It burns to $\ce{CO2}$, which reduces the ore.

Coke burns to $\ce{CO2}$, and $\ce{CO2}$ reacts with more coke to give CO, which reduces the ore: $\ce{3CO + Fe2O3 -> 2Fe + 3CO2}$. So coke is the source of CO, the reducing agent.

[ar-EG] الـ coke بيتحرق ويدي $\ce{CO2}$، والـ $\ce{CO2}$ بيتفاعل مع coke زيادة ويدي CO، والـ CO ده هو اللي بيعمل reduction للـ ore: $\ce{3CO + Fe2O3 -> 2Fe + 3CO2}$. يعني الـ coke هو مصدر الـ CO، اللي هو الـ reducing agent.
## 9. Summary

$\ce{C + O2 -> CO2}$, then $\ce{CO2 + C -> 2CO}$. $\ce{3CO + Fe2O3 -> 2Fe + 3CO2}$, higher than 700 °C. CO is the reducing agent; coke is its source. Role of coke: "a source of carbon monoxide, the reducing agent". Write the three equations. Back to the hook: can you explain why CO, not $\ce{CO2}$, reduces the ore? In $\ce{CO2}$, carbon already holds two oxygen atoms, so it cannot take one more. CO can still gain an oxygen atom: $\ce{3CO + Fe2O3 -> 2Fe + 3CO2}$.



Chapter: Transition Elements (https://yaani.ai/ar/learn/chemistry/chem-s3-en.ch1)
Source: https://yaani.ai/ar/lesson/chem-s3-en.lesson-fe.blast-furnace-reduction