# Reduction in the Midrex furnace

> Natural gas gives two reducing agents


## Objectives

- Write the equation that turns natural gas into water gas.
- Write the reduction equation of the ore by CO and H₂.
- Explain the role of natural gas and compare with the blast furnace.

## 1. Iron ores and extraction of iron




## 2. Iron without coke?

Predict: in the Midrex furnace, what reduces the iron oxide?

- A mixture of CO and $\ce{H2}$ made from natural gas ✓
- Oxygen gas
- Methane, $\ce{CH4}$, directly
- Coke, as in the blast furnace

In the Midrex furnace a mixture of CO and $\ce{H2}$ (water gas), made from natural gas, reduces the iron oxide. Methane is changed into these gases first, no coke is used, and oxygen would add oxygen instead of removing it.

[ar-EG] في الـ Midrex furnace، خليط من الـ CO والـ $\ce{H2}$ (الـ water gas) جاي من الـ natural gas هو اللي بيعمل reduction للـ iron oxide. الـ methane بيتحوّل للغازين دول الأول، ومفيش coke بيُستخدم، والـ oxygen هيزوّد oxygen بدل ما يشيله.
## 3. Natural gas becomes water gas

Water gas A mixture of carbon monoxide and hydrogen. Natural gas (93% methane) is changed into water gas: $\ce{3CO + 5H2}$. Atoms are conserved


## 4. Two reducing agents

Both CO and $\ce{H2}$ take oxygen from the ore. So both are reducing agents.


## 5. Share the oxygen

Two $\ce{Fe2O3}$ hold 6 O atoms. Each CO or $\ce{H2}$ takes one. Set the mix. CO molecules H₂ molecules O removed O still on the iron This is the book's mix: 3CO + 3H₂ remove all 6 O atoms.


## 6. Balance it

The reducing gases are given. Fill in the iron oxide and the iron. Complete the Midrex reduction equation.


## 7. Blast furnace vs Midrex

Methane reduces the ore.


## 8. Check yourself

Exam question: "Explain the role of natural gas in the Midrex furnace." Which answer gets full marks?

- It burns coke to make CO.
- Methane reduces $\ce{Fe2O3}$ directly to iron.
- It is the source of water gas (CO + $\ce{H2}$), which reduces the iron oxide. ✓
- It dries the ore and expels humidity.

Natural gas (93% methane) is the source of water gas, CO + $\ce{H2}$: $\ce{2CH4 + CO2 + H2O -> 3CO + 5H2}$. These two gases reduce the iron oxide: $\ce{2Fe2O3 + 3CO + 3H2 -> 4Fe + 3CO2 + 3H2O}$.

[ar-EG] الـ natural gas (93% methane) هو مصدر الـ water gas، يعني CO + $\ce{H2}$: $\ce{2CH4 + CO2 + H2O -> 3CO + 5H2}$. والغازين دول هما اللي بيعملوا reduction للـ iron oxide: $\ce{2Fe2O3 + 3CO + 3H2 -> 4Fe + 3CO2 + 3H2O}$.
## 9. Summary

$\ce{2CH4 + CO2 + H2O -> 3CO + 5H2}$ (water gas). $\ce{2Fe2O3 + 3CO + 3H2 -> 4Fe + 3CO2 + 3H2O}$. Blast furnace: CO from coke. Midrex: CO + H₂ from natural gas. Role of natural gas: "a source of the reducing mixture of carbon monoxide and hydrogen (water gas)". Back to the hook: can you explain how the Midrex furnace reduces the ore with no coke? Natural gas is changed into water gas, a mixture of CO and $\ce{H2}$: $\ce{2CH4 + CO2 + H2O -> 3CO + 5H2}$. Both gases take oxygen from the ore: $\ce{2Fe2O3 + 3CO + 3H2 -> 4Fe + 3CO2 + 3H2O}$.



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