Method for preparing oxidated pellets from pure hematite concentrate

Abstract

A method for preparing oxidated pellets from pure hematite concentrate includes the following steps: after the hematite concentrate is preprocessed until the specific surface area is larger than or equal to 1300cm2.g-1, compound additive which accounts for 0.5 to 1.6 percent by weight of the total amount of hematite concentrate is added, damp milling is then carried out, pelletizing, drying, preheating and roasting are sequentially carried out after damp milling, and thereby the finished oxidated pellet product is obtained. The compound additive is the mixture of humic acid, calcium peroxide and paigeite, the mixture is ground to the grain size of negative 0.074mm after mixing, and the percentage by weight is not lower than 95 percent. The method solves the problems in the preparation of oxidated pellets from the hard-to-pelletize, hard-to-roast hematite concentrate, such as poor pellet quality, high preheating and roasting temperatures, long time, low finished pellet product strength. The method is simple, the quality of the prepared hematite concentrate pellets is high, the preheating and roasting temperatures are low, the time is short, and the method is suitable for the preparation of the oxidated pellets from the hematite concentrate, particularly the preparation of the oxidated pellets from hard-to-pelletize, hard-to-roast spiegeleisen concentrate. The method can realizeindustrialized production.

Description

technical field [0001] The invention relates to a method for preparing iron ore oxidized pellets, in particular to a method for preparing oxidized pellets from whole hematite concentrate. The invention belongs to the technical field of iron and steel metallurgy pellet preparation. Background technique [0002] In recent years, in order to implement the "concentrate" policy of blast furnace ironmaking, the proportion of acid oxidized pellets in most domestic blast furnaces has been increasing year by year. Magnetite concentrate is a recognized high-quality raw material for the production of oxidized pellets, but with the increase in demand for acidic pellets, the supply of high-quality magnetite resources for iron ore pellet production is becoming increasingly tight. The use of imported high-quality iron ore resources is a necessary way to alleviate the shortage of raw materials for pellet production in my country. However, most of the imported high-quality iron concentrate...

AI Technical Summary

Problems solved by technology

When it is used to produce oxidized pellets, there are mainly two problems as follows: one is that the raw material has poor ball forming ability, so more bentonite has to be added to ensure the quality of the green pellets. Generally, the amount of bentonite added is 2% to 3%, so that the grade of finished pellets is significantly reduced; second, the required preheating and roasting temperature is high, and Fe can only be observed when the roasting temperature exceeds 1300°C 2 o 3 When the crystal grains grow obviously, the connecting bridges will be formed between the grains; the crystal grains can only recrystallize at 1350°C, thus ensuring the strength of the pellets

Although this method has a certain effect, there are problems such as low processing capacity, high energy consumption and high steel consumption in lubricating grinding, and the power consumption of high-pressure roller milling is also high; 2) use modified bentonite or pure organic binder (CMC, Palido, etc.) replace bentonite in whole or in part, and the spheroidization and green pellet quality of raw materials are improved to a certain extent, but there are problems such as low pellet strength and TFe grade, or lower bursting temperature of green pellets; 3) adding carbon Substances can improve the preheating roasting performance of specularite or hematite pellets to a certain extent, but the strength of green pellets is not significantly improved, and the burst temperature will decrease due to internal carbon; 4) internal Adding magnetite can significantly improve the preheating roasting performance of specular (red) iron ore, but the addition of magnetite must reach more than 30% to show better results. When using specular iron ore with magnet When producing pellets, the proportion of magnetite is required to reach more than 70%. This method requires the pelletizing plant to purchase a large amount of magnetite; It is good to improve the preheating and roasting performance of mirror (red) iron ore, but the products produced are mostly flux pellets, and the structure and properties of the charge will change significantly when added to blast furnace smelting, thus affecting the technical and economic indicators of blast furnace ironmaking

[0005] Therefore, in order to effectively solve the problems of difficulty in forming pellets when Quanjing (red) iron ore is used in the production of oxidized pellets, and the problems of high preheating roasting temperature and long time in the preheating roasting process, the development of Quanjing (red) iron ore ) an effective method for preparing oxidized pellets from iron ore concentrates, which alleviates the shortage of magnetite raw materials for domestic iron ore pellet production, and proposes the present invention