# Ore dressing: crushing, sintering, concentrating

> Getting the ore ready for the furnace


## Objectives

- State that ore dressing improves the ore's physical and mechanical properties (and its chemical properties).
- Give the purpose of crushing, sintering and concentrating.
- Explain that impurities mixed with the ore are separated by surface tension, magnetic or electric separation.

## 1. Iron ores and extraction of iron




## 2. Straight from the mine

Predict: why are the rocks crushed first?

- Crushing turns the iron oxide into iron
- To get pieces of a suitable size, so the ore is easily reduced ✓
- Crushing removes all the impurities

Crushing breaks the rocks into pieces of a suitable size, so the ore is easily reduced. Breaking the rock does not remove the impurities or turn the iron oxide into iron.

[ar-EG] الـ crushing بيكسّر الصخور لحتت بحجم مناسب، عشان الـ ore يتختزل بسهولة. وتكسير الصخرة مش بيشيل الشوائب ولا بيحوّل الـ iron oxide لـ iron.
## 3. What ore dressing does

Ore dressing The processes that prepare iron ore for reduction, by improving its physical, mechanical and chemical properties. This lesson covers the three processes of part 1.


## 4. a- Crushing

Crushing gives the ore a **suitable size**, so it is easily reduced. Pieces along each edge of the rock Pieces Surface exposed Smaller pieces expose more surface to the substance that reduces them. But crushing also makes very fine particles. Too fine is a problem too: see the next step.


## 5. b- Sintering

Crushing and cleaning the furnace leave a huge amount of fine particles. They cannot be used directly in the blast furnace (where the ore is reduced). Sintering Treating the fine ore particles to collect them into larger lumps that are similar and homogeneous. Sintering means melting the ore.


## 6. c- Concentrating

Concentrating Increasing the percentage of iron in the ore by removing most of the impurities, which are chemically combined or mixed with the ore. Impurities mixed with the ore are separated by surface tension, magnetic or electric separation. Made-up sample: 100 kg of ore holding 50 kg of iron. Remove impurities and watch. Impurities removed Iron in the sample Iron %


## 7. Which process?

Each ore sample has one problem. Which process fixes it?


## 8. Apply: concentrate it

Crushed magnetite ore is mixed with sand. Which method best concentrates it?

- Melting the ore
- Magnetic separation ✓
- Sintering

Magnetite has magnetic properties and sand does not, so magnetic separation removes the mixed sand and concentrates the ore. Sintering joins fine particles into lumps without removing the sand, and melting does not sort the sand out.

[ar-EG] الـ magnetite ليه خواص مغناطيسية والرمل لأ، فالـ magnetic separation بيشيل الرمل المخلوط ويركّز الـ ore. الـ sintering بيجمّع الحبيبات الناعمة في كتل من غير ما يشيل الرمل، والصهر مش بيفصل الرمل.
## 9. Summary

**Crushing**: gives a suitable size, so the ore is easily reduced. **Sintering**: collects fine particles into larger, similar, homogeneous lumps. No melting. **Concentrating**: raises the iron % by removing most of the impurities. Mixed impurities go by surface tension, magnetic or electric separation. Part 1 of ore dressing; roasting (part 2) comes next Can you explain why both crushing and sintering are needed? Give reasons: sintering is needed. Fine particles from crushing and furnace cleaning cannot be used directly in the blast furnace.



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