Iron ore size classification
1. Granularity of ore: The granularity and porosity of ore have a great influence on the process of blast furnace smelting. Too small particle size affects the gas permeability of the material column in the blast furnace and increases the gas rising resistance. Excessive particle size will affect the heating of the charge and the reduction of the ore. Due to the large particle size, the contact area between the gas and the ore is reduced, and the central part of the ore is not easy to be reduced, thereby reducing the reduction speed and increasing the coke ratio.
2. Coarse powder: basically 0-10 mm, but generally no more than 10% above 10 mm, and no more than 35% below 0.15 mm.
3. Fine powder: basically domestically produced, below 200 mesh. Generally, foreign ore in China is coarse powder, and now imported fine powder is also used, such as Russian fine powder, Ukrainian fine powder and Brazilian SSFT powder. The fine powder requires no less than 70% below 0.074mm.
4. Lump ore: There are two types, one is standard lump, with a particle size of 6-40 mm. The other is a mixed block, which generally needs to be screened and broken before it can be used.
5. Raw ore: The raw ore is mined from the mine without beneficiation or other technical processing, but the particle size of the raw ore is preferably not more than 300 mm. A small number of raw ore can be directly used, and most of the raw ore can only be used after beneficiation or other technical processing. In beneficiation, the ore that has been crushed to enter the separation operation is called the selected ore.
6. Fine ore: powder ore, English name: fine ore; mine smalls; ore fines; smalls; its grade is lower than lump ore, it needs to be crushed\grinding\sorting to turn the lump into powder to achieve the grade The general requirement is 60-67%, and the grade of Panzhihua Iron and Steel is 57%.
Types of iron ore smelting
1. Acid sinter:
Sintered ore with alkalinity (CaO/SiO2) less than 0.5 is sintered from iron concentrate or rich ore powder without or with less flux. Its iron-containing minerals are magnetite and hematite, and the main binding phase minerals are iron olivine (2FeO SiO2) and calcium iron olivine (CaOFeOSiO2). The red hot acidic sinter does not naturally pulverize during the cooling process. It has high mechanical strength, but high FeO, poor reducibility, and low reflow temperature; using this ore alone for smelting requires a large amount of limestone; and poor reducibility, resulting in low blast furnace output and high coke ratio. Except for some special circumstances, modern blast furnaces no longer use this kind of sinter.
2. Iron ore concentrates:
High-grade iron ore powder obtained by fine grinding and selection of lean iron ore. Iron concentrate is a raw material for iron and steel metallurgy to produce man-made rich ore. According to different iron-containing minerals, iron concentrates are divided into magnetite concentrates, hematite concentrates and limonite concentrates; according to different beneficiation methods, they can be divided into weak magnetic concentrates, strong magnetic concentrates, and flotation. Concentrates and heavy separation concentrates, etc. Magnetite concentrate is usually obtained by processing magnetite by magnetic separation; hematite concentrate is processed by gravity separation, flotation, strong magnetic separation, magnetized roasting-magnetic separation, or combined process to treat hematite ore Obtained; limonite concentrate is obtained by processing limonite ore by gravity separation, strong magnetic separation, or magnetic roasting-magnetic separation.
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