Method for improving compressive strength of alkali pellets prepared with limestone

Abstract

The invention relates to a method for improving the compressive strength of alkali pellets prepared with limestone. The method comprises the following steps of: grinding the limestone into superfine particle size of less than 3 microns, adding the limestone powder of superfine particles into pellet concentrate powder with the particle size of less than 74 microns, adding water, and mixing uniformly in a mixer, wherein an adhesive is not used in proportioning; and pelletizing the uniform mixture, and roasting the screened fresh pellets. The roasting process comprises drying, preheating, roasting, soaking and cooling; and oxygen enrichment is performed in the preheating and roasting processes, the oxygen content in the preheating process is kept between 12 and 15 percent, and the oxygen content in the roasting process is kept between 10 and 12 percent. The problem that the compressive strength of the alkali pellets prepared with the limestone obviously declines is effectively solved through the measures of grinding of the limestone, oxygen enrichment in the roasting process and the like.

Description

technical field

[0001] The invention relates to the technical field of iron ore pellet production for blast furnace ironmaking, in particular to a method for increasing the compressive strength of pellets mixed with limestone. Background technique

[0002] Pellets are one of the main raw materials for blast furnace ironmaking. At present, my country's pellet production capacity has reached 200 million tons, but the main production is ordinary acid pellets. Acid pellets are pellets of natural alkalinity, SiO 2 and Al 2 o 3 The content of other elements is relatively high, while the content of alkaline substances such as calcium and magnesium is low, so it can only be used in conjunction with high-basic sintered ore in blast furnaces. Pellets with binary alkalinity above 0.6% are called alkaline pellets. Alkaline pellets have the advantages of high reducibility and good droplet performance, but it is difficult to improve the compressive strength of alkaline pellets, especi...

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