Composite additive for preparing hematite concentrate pellet and application thereof

Abstract

A composite additive for preparing hematite concentrate pellets comprises the following components: humic acid, calcium peroxide, and paigeite. During application, the composite additive is added which has a mass percent of 0.5%-1.6% of the total mass of the hematite concentrates, and the finished product pellets are obtained by pelletization, preheating, and roasting. Compared with pellets prepared by traditional technology, the hematite pellets prepared by the composite additive of the invention have improved falling strength of the green pellets, and compression strength of the finished product pellets; the preheating temperature and roasting temperature suitable for the pellets are reduced; both the preheating time and roasting time are shortened; the TFe grade is increased by 0.8%-1.2%. The composite additive of the invention has reasonable component ratios, is easy to process and manufacture, has a low using amount and a low residual amount, can significantly improve the pelletability of hematite concentrates which are difficult to be palletized, can improve the green pellet quality, has good heat stability, and can effectively reduce the preheating and roasting temperatures and shorten the preheating and roasting time of hematite concentrates. The composite additive of the invention is applicable to the production of oxidized pellets by hematites, and is especially applicable to the production of oxidized pellets by specularites. The composite additive of the invention is applicable to large-scale industrial production.

Description

technical field [0001] The invention relates to an additive for producing iron ore pellets and its application, in particular to a composite additive for preparing hematite pellets and its application. The invention belongs to the technical field of iron and steel metallurgy pellet preparation. Background technique [0002] Production practice has proved that magnetite concentrate is a high-quality raw material for producing oxidized pellets. Since the 21st century, with the rapid development of my country's iron and steel industry, major domestic iron and steel enterprises are vigorously developing the iron ore oxide pellet production process based on the grate-rotary kiln method. According to reports, in 2010, the domestic production of oxidized pellets reached over 110 million tons. The vigorous development of the oxidation pellet industry has led to an increasing shortage of high-quality magnetite concentrate raw materials for pellet production. Therefore, the product...

AI Technical Summary

Problems solved by technology

When hematite and specularite are used to produce oxidized pellets, there are mainly two problems: one is that the raw materials have poor ball forming properties, so more bentonite has to be added to ensure the quality of the green pellets. The amount of bentonite added in the preparation of oxidized pellets is generally 2% to 3%, so the grade of the finished pellets is significantly reduced; second, the required preheating and roasting temperature is high, and only when the roasting temperature exceeds 1300 ° C, can it be Fe was observed 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