First, the iron ore varieties
1. PB Fines/Pb Lumps: Produced in Australia, also known as Pilbara mixed mine (manufactured by BHP Billiton), the grade of powder is about 61.5%, and some lignite has good sintering performance; The grade is about 62.5%, which is limonite, with good reduction and heat intensity. PB powder and blocks can be mixed by powder mines from mines such as Tom Price, Parabude, Malandu, Brookman, Naddi and Xi'an Gilas.
2, Yandi Fines (Yandi Fines): produced in Australia (BHP Billiton company), grade is about 58%, low aluminum content, is limonite, high crystal water, high moisture requirements for mixed materials, because Its structure is loose, sintering assimilation and reactivity are good, so it can partially replace Newman Mountain Powder Mine or Brazilian Powder Mine. It contains relatively low Al2O3, and both of these mineral powders are coarser than Hamersley ore. They all have reasonable smelting properties, but the sintering performance is not good.
3, Mac Fines (Mac Fines): MAC powder's normal grade is about 61.5%, currently supplying about 58% of the Chinese market, some are limonite, good sintering performance, containing about 5% of crystal water, When the iron is ironed, the burning loss is higher, and as the ratio is increased, the firing rate of the sintered ore is gradually decreased. According to the steel mill research, when the MAC powder ratio is 15%-20%, the sintered ore is lower than the 5mm level, and the ratio of 20% is the highest.
4. Newman Fines/Newman Lumps: Newman Mountain Mine in Newman Town, East Pilbara, Australia. It is a hematite with good sintering performance and a grade of 62.5%. The grade is around 65% and is produced by BHP Billiton, Western Australia.
5, Robe River Fines/Robe River Lumps: produced in Australia's Rob River Iron Ore Joint Company; grade is about 57.5%, containing 3%-5% of compound water, which leads to high fuel rate And low productivity; belongs to limonite, the sintering performance is not good, but the smelting performance of its sinter is very good.
6, rocket powder: also known as FMG (Fortescue Metal Group (Fortescue me tal Group (FMG) )) powder from Australia's third largest iron ore producer FMG company; allegedly used as a fuel in a rocket engine The composition, so called rocket powder, its grade is about 58.5%, silicon about 4, aluminum 1.5 or so, belongs to limonite, good sintering performance, large reserves and high single-burning grade, crystal water is about 8%. The chemical composition of FMG powder ore is worse than that of Yandi powder, but the sintering performance and pelleting performance are not as good as Yandi powder.
7. Rocket special powder: Rocket powder of about 57.5% grade produced by FMG company, about 5 silicon, 2 aluminum, and other smelting performance with rocket powder. The grade of super special powder is lower than that of rocket special powder, which is about 56.5%, about 6 silicon, about 3 aluminum, and about 8.5% crystal water. Other smelting performance is similar.
8. Atlas powder: iron ore at the Pilbara mine in Australia, produced by Australia's fourth largest iron ore producer Atlas Iron, with a grade of 57.5%, is a limonite, and crystal water is 9%. Left and right, the silicon content is high, at around 8%, the physical and chemical properties and smelting performance are similar to those of the rocket powder.
9. KMG powder: Produced by Australian private mining company KMG, which is located in Perth, Australia, is the closest Western Australia mine to China, close to the northernmost port of Western Australia. The mine is expected to produce 67 million tons of ore within two years, which is 58-59% of low grade coarse powder hematite, 8% silicon, 3% aluminum, 0.08% phosphorus and 0.03% sulfur. The performance is similar to rocket powder, but much higher than the rocket powder.
10, CSN powder, block: Brazil's CSN company (full name is Brazil's state-owned ferrous metal company) produced iron ore, iron content of more than 65%, silicon content of 1% -2%.
11. SSFT powder: Sintered powder specially prepared by the Brazilian Vale Company for the Chinese market. The iron content of SSFT is about 65%, and the silicon content is about 4.4%.
12, card powder: the abbreviation of Caragas powder, the English abbreviation SFCJ powder, the full name of SINTER FEED CArajas, iron content of more than 65% (65-67%), silicon content of 1% -2%. Aluminum is about 1%, phosphorus is 0.033-0.045%, burned about 1.6%, and moisture is 8-9%. It is produced in iron ore from the Caragas mine in Brazil. Because the quality of the fine ore in this place is excellent, it will not be like the southern mine. That kind of difference, so it is very popular in the international market, and the price is higher than the southern mining source.
13. Southern Brazil Powder: The mine is located in the southern part of Brazil, the “iron four cornersâ€, also known as the southern Brazilian powder. The main mines in the southern mining area are Itabira, Mariana, Mihas Centrals, ParaopeBAl, VarGEm Grande, Itabiritos, all located in the four corners of Brazil. The main mining method in the southern mining area is open pit mining. This zone is dominated by iron ore, with high hematite content and iron content of around 66%. Mainly includes SSFG powder (standard sinter powder in southern Brazil, iron grade 65%, silicon 3.2-3.8%, aluminum 1.2-1.8%, phosphorus 0.049-0.065%, manganese 0.25-0.40%, water 6.5-8.5%, burn loss 1.7% Left and right), SFOT powder, etc.
14. Barley: refers to the Brazilian coarse-grained powder mine, which is the collective name of Brazilian coarse powder, including card powder, SSFT powder, CSN powder, southern powder and so on. The grades range from 65% to 58%, and the smelting performance of the ore powder produced by the iron horn in the southeast is the best.
15. Printing powder: refers to Indian fine particle powder ore, but does not meet the graininess standard of printing. The grade ranges from 40% to 63.5%. It belongs to hematite. It has excellent high-grade smelting performance, high-grade silicon-aluminum composition and high smelting value.
Second, iron ore particle size classification
1. Granularity of ore: The size of the ore and the size of the porosity have a great influence on the progress of blast furnace smelting. When the particle size is too small to affect the air permeability of the material column within the furnace, the coal gas increased resistance is increased. 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 center portion of the ore is not easily reduced, so that the reduction rate is lowered and the coke ratio is increased.
2, coarse powder: basically 0-10 mm, but generally not more than 10% above 10 mm, the maximum not more than 35% below 0.15 mm.
3, fine powder: basically domestic production, below 200 mesh. The domestic general use of minerals is coarse powder, and now also imported fine powder, such as Russian fine powder, Ukrainian fine powder and Brazilian SSFT powder. Fine powder requires not less than 70% of 0.074mm or less.
4, lump ore: There are two, one is a standard block, particle size 6-40 mm. The other is a mixing block, which usually needs to be screened and broken before it can be used.
5. Raw ore: The original ore is mined from the mine without ore processing or other technical processing, but the ore size is preferably not more than 300 mm. A small number of ore can be directly applied, and most of the ore needs to be processed by mineral processing or other techniques. In ore dressing, the ore that has been crushed into the sorting operation is called the ore.
6, powder ore: powder ore, English name: fine ore; mine smalls; ore fines; smalls; its grade is lower than the lump ore, need to be sorted by crushing grinding, the block into powder, in order to meet the grade requirements Generally, 60-67% is required, and the grade of Panzhihua Steel can be 57%.
Third, iron ore smelting types
1. Acid sinter:
A sintered ore having a basicity (CaO/SiO2) of less than 0.5 is formed by sintering iron concentrate or rich ore powder without or with a flux. Its iron-bearing minerals are magnetite and hematite. The main binder phase minerals are fayalite (2FeO SiO2) and calcium olivine (CaOFeOSiO2). The red hot acid sinter does not naturally pulverize during the cooling process. The mechanical strength is high, but the FeO is high, the reducing property is poor, and the reflow temperature is low; when the ore is used for furnace smelting alone, a large amount of limestone is added; and the reducing property is poor, resulting in low blast furnace output and high coke ratio. In modern blast furnaces, such sinter is not used except in certain special cases.
2, iron ore concentrates (iron ore concentrates):
Iron ore fines with fine iron grades obtained by fine grinding and selection. Iron concentrate is a steel and metallurgical raw material for the production of man-made ore. Iron concentrates are classified according to different iron-bearing minerals, such as magnetite concentrate, hematite concentrate and brown iron concentrate. According to different ore dressing methods, they can be divided into weak magnetic concentrate, strong magnetic concentrate and flotation. Concentrates and re-election of concentrates. Usually, magnetite concentrate is obtained by magnetic separation of magnetite ore; hematite concentrate is treated by re-election method, flotation method, strong magnetic separation method, magnetization roasting-magnetic separation method, or combined process for treating hematite ore The obtained; the limonite concentrate is obtained by treating the limonite ore by a re-election method, a strong magnetic separation method or a magnetization roasting-magnetic separation method.
There are generally 4 requirements for iron concentrates:
(1) The amount of iron is high. The iron concentrate of the magnet concentrate should be above 65%, the hematite concentrate should be above 60%, and the brown iron concentrate should be above 50%. The fluctuation of iron content is less than ±0.5%.
(2) The moisture should be low. Moisture has a great impact on storage and transportation, ore mixing, and pelleting. Generally, the water content of the magnet concentrate should be less than 10%, and the moisture of the hematite concentrate and the brown iron concentrate should be less than 12%.
(3) The particle size is suitable. The iron concentrate used for the production of pellets requires a fraction of less than 0.074 mm to be more than 70%, and a specific surface area of ​​1200 to 2000 cm 2 /g.
(4) The lower the content of impurities (such as sulfur, phosphorus, lead , arsenic , zinc , copper and other harmful elements), the better, generally requires s ≤ 0.10% ~ 0.19%, P ≤ 0.05% ~ 0.09%, Pb ≤ 0.1% , As ≤ 0.04% to 0.07%, Zn ≤ 0.1% to 0.2%, and Cu ≤ 0.1% to 0.2%.
The acidity and alkalinity of iron concentrate (including iron ore) refers to the pH of the gangue component in the ore, specifically the ratio of calcium oxide to silica. If CaO/SiO2 is greater than 1, it is alkaline ore, and CaO/SiO2 is less than 1. It is an acid mine. If the magnesium oxide ore, high alumina content, but also the (CaO + MgO) / (SiO2 + Al2O3) is greater than 1 as the alkaline mineral, and vice versa for acid mine.
The pH of iron concentrate is related to the ironmaking index of the blast furnace. If the blast furnace uses alkaline smelting (for better desulfurization), it is desirable to use alkaline ore; if the blast furnace is acid smelting (in order to improve the utilization coefficient of the blast furnace and reduce the coke consumption) ) I hope to use acid mines. At present, the domestic blast furnace generally uses alkaline ore, that is, it is desirable that the alkalinity of the iron ore (the value of CaO/SiO2) is higher.
The pH of iron fine powder is calculated by the following formula:
(CaO+MgO)/(SiO2+Al2O3)>1.2; alkaline ore;
(CaO+MgO)/(SiO2+Al2O3)=0.8~1.2; autolyzed ore;
(CaO+MgO)/(SiO2+Al2O3)=0.5~0.8; semi-auto-dissolved ore;
(CaO+MgO)/(SiO2+Al2O3)<0.5; acid ore;
It can also be simplified to evaluate the CaO/SiO2 ratio.
Most of the domestic iron ore is low CaO, MgO, high SiO2, Al2O3 acid ore
Fourth, the impact of harmful elements
Harmful elements generally refer to sulfur (S), phosphorus (P), potassium (K), sodium (Na), lead (Pb), Zn (zinc), As (arsenic), Cu. Usually the requirements for iron ore in blast furnace smelting are as follows:
1), Pb < 0.1%, Zn < 0.1%, As < 0.07%, Cu < 0.2%, and K2O + Na2O ≤ 0.25%.
2) Sulfur (S): Sulfur is the most harmful component to steel, which makes the steel "hot brittle". The iron content in the iron ore is high, and the cost of desulfurization in the blast furnace is increased, so the less sulfur in the iron ore entering the furnace, the better.
3) Phosphorus (P): Phosphorus is also one of the most common harmful elements in steel, which makes the steel "cold and brittle". Phosphorus in iron ore is 100% into pig iron during smelting of blast furnace, and can not be dephosphorized by sintering. The phosphorus content of pig iron is mainly controlled by controlling the phosphorus content of iron ore. Dephosphorization can only be carried out by steelmaking, which increases the dephosphorization cost of steelmaking. Therefore, the lower the phosphorus content of iron ore, the better.
3), alkali metals: alkali metals mainly have potassium and sodium. The effect of potassium and sodium on the blast furnace is not proportional to the nature. The blast furnace itself has a certain ability to discharge alkali, and the alkali metal has little effect on the blast furnace within the control range. However, the alkali metal content of the iron ore in the furnace is too much, and the alkali metal enrichment is formed beyond the capacity of the blast furnace to discharge alkali, resulting in the alkali metal content of the upper charge in the blast furnace greatly exceeding the original level of the charge. The iron ore contains more alkali metal, which is easy to cause the softening temperature to decrease, and the soft melt zone moves up, which is not conducive to the development of indirect reduction, resulting in an increase in coke ratio. The inclusion of an alkali metal in the pellet causes an abnormal expansion of the pellet to cause severe chalking and deteriorate the gas permeability of the pellet. Alkali metal coke performance damage is also very serious. In addition, the alkali metal compound in the upper part of the blast furnace adheres to the furnace wall, causing the furnace wall to thicken, nodule and destroy the brick lining. Therefore, the lower the alkali metal content of the iron ore, the better.
4) Lead (Pb): Lead is almost completely reduced in the blast furnace. Because the density is as high as 11.34t∕m3, it sinks under the dead iron layer and easily breaks the brick bottom seam, which may cause the bottom of the furnace to burn through.
5), zinc (Zn): zinc is easily vaporized, zinc vapor easily enters the brick joint, oxidizes into ZnO and expands, destroying the refractory brick lining on the furnace body.
6) Arsenic (As): Arsenic is also one of the harmful elements for steel. It makes the steel cold and brittle, which makes the welding performance of the steel worse. The arsenic in iron ore is basically reduced into pig iron, which affects the quality of pig iron. In addition, arsenic volatilizes during the sintering process, which has a great impact on the environment.
7), copper (Cu): copper will make the steel "hot brittle", steel is not easy to roll and weld. A small amount of copper can improve the corrosion resistance of steel. In blast furnace smelting, all copper is reduced into pig iron.
8) Titanium (titanium): It can improve the wear resistance and corrosion resistance of steel. However, in the smelting of the blast furnace, the properties of the slag deteriorate, and about 90% of the titanium enters the slag. When the content of titanium is low, it has little effect on the slag and the smelting process. When the content is high, the slag will become thicker and the fluidity is poor, which has great influence on the smelting process and is easy to form a furnace. Titanium has a role in protecting the furnace. Many blast furnaces specialize in buying titanium ore to join the blast furnace.
V. Introduction to the four major iron ore indices
There are four influential iron ore spot indices in the international market, one is Platts' Platts Index, the other is Global Steel (SBB)'s TSI index, and the third is the Metal Guide (MB). The MBIO index, the fourth is the China Iron Ore Price Index. Due to the different methods of compiling the four indexes, the quotations are not the same, and even the trend direction is different.
The Platts Index is to use mines, traders, steel mills, freight forwarders, financial institutions, etc. as inquiry objects. Every day, Platts editors will contact them to inquire about the trading situation on the day and how to look at the price. Think of the most competitive price on the day as "assessed price."
The TSI index pays more attention to the actual transaction price every day. Steel mills, mines and traders are their inquiry objects, and they account for the basic three-three system. They upload the actual transaction price every day, and TSI analysts calculate and give The same weights of steel mills, mines and traders are finally summarized into the CIF price of imported iron ore from two grades (62% and 58%) to Tianjin Port.
The MBIO index is based on 62% grade iron ore from China Qingdao Port (CFR), which converts all 56% to 68% grade iron ore to 62% grade.
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