How is iron ore processing done?

Ore processing

For technical and economic reasons, ores have to be processed before being smelted.

This is done by:

  • Shredding large pieces

  • Compression of fine-grained dust

  • To reduce

  • Enrich

The question is::
What is the cheapest way of getting the mountain into the furnace piece by piece?



Enrichment means the separation of ore-containing and mineral rocks (the so-called gangue).

The production of pig iron is made difficult by a high proportion of mineral components. These have to be melted together with the ore with a high expenditure of energy. Enrichment can also make ores with a lower iron content economically smeltable.

Enrichment can be done in different ways. Some methods are described below to help you understand.

Magnetic separation of iron ores:

In this process, the ore-free, deaf rock is magnetically separated from the ferrous rock.

Magnetic iron stone is easy to magnetize. In terms of process technology, weak magnetic fields from permanent magnets (permanent magnets) are sufficient. The ore has to be ground to grain sizes of 0.01 ... 2mm for separation.

Roteisenstein is a weakly magnetizable ore. It is ground to grain sizes of 0.02 ... 1mm and separated from electromagnets with strong magnetic fields.

If the magnetic fields are strong enough, it is also possible to separate titanium, chromium, manganese and nickel compounds from the gangue.

Wet processing of iron ores:

The chemical compound (oxide, sulfide) contained in the metal is heavier than the gangue. A certain liquid is prepared for the separation, in which the gangue swims and the heavy ore sinks under.

Flotation (Swimming pool treatment)

This method makes use of the property of water that not all substances can be wetted in the same way. This behavior can be intensified by chemicals.

The finely ground ore is kept in suspension in the water by the agitator. Air is blown in from below. The rising air bubbles carry the particles not wetted by the water upwards. The chemicals cause foam to form on the surface, which holds the particles in place. The foam can be pulled off with the particles.



Roasting is the heating of the ground ores with a controlled access of air. Depending on the ore, roasting has different tasks:

Sulphides are roasted to convert them into oxides. The sulfur burns to sulfur dioxide (SO2). This is processed into sulfuric acid.

Spateisenstein is roasted into Roteisenstein.

Magneteisenstein and Roteisenstein are roasted to make them crack. This promotes the blast furnace process.

Roasting turns SO2, CO2 and also expelled water. This reduces the weight of the ores by up to 30%. If the ore is roasted at the place of discovery, the freight costs to the steelworks can be reduced considerably.


Production of the cheapest grain size

Sieving and breaking

Enrichment and smelting require certain grain sizes. Dust and fine ores have to be sieved off, large chunks have to be crushed. For the blast furnace process, grain sizes of approx. 30mm have proven to be favorable.

Making lumpy

For smelting, fine ores have to be brought to a certain grain size so that they do not clog the furnace.


Sintering is the heating of the fine material to temperatures of 900 ... 1350 ° C. In doing so, the gangue begins to partially melt and the fines are baked together. Porous and therefore gas-permeable pieces are created. These can be reduced very well.

Pelletizing (pellet)

Pelletizing has proven to be beneficial for fine ores with grain sizes below 0.2mm. In this process, the fine ores are mixed with binding substances and rolled into pellets. The soft pellets have to be sintered in shaft or rotary kilns so that they can withstand the high pressure of the weight in the blast furnace.