Preparation method for boron-magnesium composite additive for pellets and product

Abstract

The invention discloses a preparation method for a boron-magnesium composite additive for preparing pellets and a product. The method is characterized by comprising the following steps: crushing and drying magnesium ore serving as a raw material; roasting at the temperature of between 750 and 900DEG C for 30 to 120 minutes, taking out of a furnace, cooling, and grinding to obtain magnesium ore powder; grinding a boron-containing material of which the B2O3 grade is 5to 15 percent to obtain boron powder, mixing the two kinds of powder in a ratio to obtain the boron-magnesium composite additive comprising the following chemical compositions in percentage by weight: more than or equal to 58 and less than or equal to 70 percent of MgO, more than or equal to 11 and less than or equal to 23 percent of SiO2, more than or equal to 3 and less than or equal to 6 percent of B2O3, less than 1 percent of Al2O3 and more than or equal to 14 and less than or equal to 18 percent of burning loss; and adding the composite additive in an amount which is 1 to 2 percent of pellet raw material into the pellet raw material for pelletizing, and roasting at the temperature of between 1,200 and 1,300DEG C for 20 to 60 minutes to obtain the pellets. By the additive, the metallurgical properties of the pellets, such as decrepitation temperature, compressive strength, drop strength, low temperature reduction degradation index, medium temperature reducibility and reduction swellability can be obviously improved.

Description

technical field [0001] The invention relates to a preparation method and a product of an additive used for preparing metallurgical pellets, especially an additive used to improve the quality and metallurgical performance of metallurgical pellets. Background technique [0002] As we all know, the pellets used in ironmaking mainly use bentonite as an additive. Because of its good cohesiveness, it has better strength after being added to the green balls of the pellets. However, the main component of bentonite is SiO 2 and Al 2 o 3 , for every 1% of bentonite added, the grade of pellets will decrease by about 0.7%. If the amount is too large, not only will the SiO in the pellet 2 The content increases, and fayalite is easy to be produced during the high-temperature reduction process, which is not conducive to the effective reduction of iron elements in pellets. In addition, when producing flux-type pellets such as MgO pellets and CaO pellets, if adding bentonite on the basi...

AI Technical Summary

Problems solved by technology

[0003] In order to overcome the reduction of pellet grade due to existing binders and additives, SiO 2 The content is too high, and the pellets have poor reducibility at high temperature. The present invention provides a boron-magnesium composite additive, which is used as a binder and flux for pellets. In terms of its use effect, it can not only comprehensively improve the metallurgical properties and To meet the requirements of blast furnace slagging on MgO content, and at the same time reduce the range of pellet grade decline caused by the use of additives, especially effectively reduce SiO 2 content, improve the high temperature reduction performance of pellets

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