Different types of iron ore and their drying techniques

Drying is important in iron ore processing. By reducing the moisture content, it ensures the permeability of the ore, and provides convenience for later processing and transportation. There are many kinds of of iron ore, because of their differences in moisture, mineral morphology, and uses, it is necessary to choose the most suitable iron ore drying technique. Below, I will introduce the differences in drying techniques for magnetite, pyrite, hematite, and limonite.

Types of iron ore and drying requirements

1. Magnetite

Characteristics: Strong magnetism, wide particle size range (from coarse ore to powder).

Drying requirement: It is usually used for drying concentrate after dry magnetic separation, so it needs to be dried thoroughly to avoid affecting the magnetic separation efficiency.

2. Pyrite

Characteristic: Sulfide, often accompanied by organic matter, easily generates dust.

Drying requirement: Due to its dust problem, the drying process needs to have dust-proof capabilities; Used for pellet or roasting after drying.

3. Hematite

Characteristics: Weak magnetic or non-magnetic, containing a large amount of crystalline water.

Drying requirement: Drying is mainly used for pre drying before roasting to remove crystal water and prevent cracking during the roasting process.

4. Limonite

Characteristics: Contains crystalline water (loose water), with high viscosity.

Drying requirement: Drying processes are extremely sensitive to temperature control and are usually combined with roasting processes for treatment.

Comparison of drying technologies for various iron ores

1. Drying technology for magnetite

Rotary dryer: used for continuous drying of coarse-grained magnetite, with fast drying speed, suitable for large-scale production.

Vacuum drying: used for high-purity magnetite powder, using vacuum to reduce boiling point and protect powder activity. Mainly used in laboratories or high value-added magnetic materials fields, with less application in the mineral processing industry.

Microwave drying: suitable for fine magnetite powder, can be heated from the inside, but it is necessary to prevent powder agglomeration caused by thermal stress. At present, it is mostly for scientific research or small-scale experiments, and has not yet been widely applied in industry.

2. Drying technology for pyrite

Rotary hot air drying: Before conducting dry magnetic separation on pyrite, the moisture content needs to be reduced to the allowable range through drying to ensure the accuracy of magnetic separation.

Dehydration and concentration+drying: Due to the high moisture content of pyrite concentrate, it needs to be preliminarily dehydrated through a concentrator before entering the dryer.

3. Drying technology for hematite

Hot air pre drying: Hematite needs to be pre dried before magnetization roasting to avoid material cracking caused by water evaporation during the roasting process.

Rotary low-temperature drying: Hematite is usually pre dehydrated by setting up a low-temperature drying section or independent drying equipment before rotary kiln roasting.

4. Drying technology for limonite

Microwave drying: Due to the high moisture content of brown iron ore, traditional drying rates are slow. Research has found that microwave drying rates are 2-3 times faster than traditional drying, and the drying temperature is uniform. But energy consumption and scale are still limiting factors

Hot air circulation drying: commonly used for concentrated drying of concentrate after beneficiation of brown iron ore. It is currently the mainstream solution for beneficiation of brown iron ore

For different types of iron ore, drying technology must be closely integrated with beneficiation and subsequent metallurgical processes. When selecting a drying technology, factors such as the iron ore's magnetism, water content, and product form need to be considered. If you are interested in iron ore drying technology, please feel free to contact us for more technical information.