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CN-121976032-A - Method for reducing small fraction proportion of sinter

CN121976032ACN 121976032 ACN121976032 ACN 121976032ACN-121976032-A

Abstract

The invention relates to the technical field of iron-making sintering, in particular to a method for reducing the proportion of small size fractions of sintered ores. The method comprises the steps of increasing material layers at two side edges of a sintering trolley by 80-150 mm, performing enhanced ignition on the increased side edges to enable the surface temperature of the increased side edges to be 20-150 ℃ higher than that of a central area, adding at least one of lump ore, return ore powder or finished pellets into a mixture in the central area as an air permeability adjusting material, and controlling the adding proportion and granularity of the mixture. According to the invention, through a three-step cooperative process, the influence of edge air leakage is effectively compensated, the air permeability is improved and the sintering speed is improved while the strength of the sintered ore drum is improved and the proportion of small particle fraction (< 5 mm) is reduced, so that the synchronous optimization of quality and efficiency is realized, and the method is easy to implement and low in cost.

Inventors

  • REN WEI
  • JIN XUN
  • WANG LIANG
  • LI JINLIAN
  • HAN ZIWEN
  • LIU JIE
  • LIU SHUAI
  • GAO HONGZHUANG
  • DUAN LIXIANG
  • CHEN BOJIAN

Assignees

  • 鞍钢股份有限公司

Dates

Publication Date
20260505
Application Date
20260209

Claims (8)

  1. 1. The method for reducing the proportion of the small size fraction of the sinter is characterized by comprising the following steps of: 1) The material layer of the side material layer is heightened and distributed, namely, the height of the mixed material layers of the side areas on two sides is heightened in the width direction of the sintering trolley to be higher than the height of the material layer of the central area, and the height difference delta H between the height of the side material layer and the height of the central material layer is more than or equal to 80mm and less than or equal to 150mm; 2) The enhanced ignition of the edge material layer area after the increase in the step 1) is performed, the ignition intensity is higher than that of the central area, and the ignition temperature of the surface of the edge material layer is 20-150 ℃ higher than that of the central area; 3) The air permeability of the central area is regulated by adding an air permeability regulating material into a mixture in the central area of the sintering trolley, wherein the air permeability regulating material is at least one of lump ore, return ore powder or finished pellets, the adding proportion of the lump ore is 5% -15% based on the total mass of the mixture, the adding proportion of the return ore powder is 3% -8%, and the adding proportion of the finished pellets is 5% -10%.
  2. 2. The method according to claim 1, wherein in the step 1), the edge region is a strip region extending inward from edges of both sides of the trolley, and the width is 5% -10% of the total width of the trolley.
  3. 3. The method for reducing the proportion of small size fractions of sintered ores according to claim 1, wherein in the step 1), the difference delta H between the height of the side material layer and the height of the center material layer is 100mm < delta H < 130mm.
  4. 4. The method for reducing the proportion of small size fractions of sintered ores according to claim 1, wherein in the step 2), the intensified ignition is realized by increasing the number of ignition burners in an edge area, wherein the number of ignition burners in the edge area is 1.5-2 times that of ignition burners in a central area.
  5. 5. The method for reducing the proportion of small size fractions of sintered ores according to claim 1, wherein in the step 3), the particle size of the air permeability adjusting material satisfies the following conditions, namely, the particle size is 10-30 mm when lump ore is added, the particle size is <3mm when return ore powder is added, and the particle size is 8-16 mm when finished pellets are added.
  6. 6. The method according to claim 5, wherein in the step 3), when the added air permeability adjusting material is lump ore, the lump ore is subjected to a preheating drying process before being added.
  7. 7. The method of reducing the fraction of agglomerate according to claim 6, wherein the pre-heat drying process is heating the agglomerate to a temperature above 700 ℃.
  8. 8. The method according to claim 1, wherein in the step 3), when lump ore is added and the sinter mixture basicity R m satisfies 1.8≤R m ≤2.4, the central lump ore addition ratio R b (%) satisfies R b =0.25×(R m -1.6) 2 +5.

Description

Method for reducing small fraction proportion of sinter Technical Field The invention relates to the technical field of iron-making sintering, in particular to a method for reducing the proportion of small size fractions of sintered ores. Background Sinter is one of the most main iron-containing furnace materials for modern blast furnace ironmaking, and the quality (including chemical components, metallurgical performance and physical granularity composition) of the sinter directly influences the running state, production efficiency, energy consumption and pig iron quality of the blast furnace. The ideal sinter should have good cold strength, hot strength and uniform and suitable particle size composition. Wherein, too high a proportion of small size fraction (usually <5 mm) sinters worsens the air permeability of the blast furnace charge column, increases the resistance in the furnace, leads to an increase in fuel ratio, a decrease in yield, and may cause operational problems such as pipe strokes. Therefore, reducing the proportion of small size fraction in the sinter is one of the core goals of continuous optimization of the sintering process. In order to control the fraction of small particles, the prior art has been largely explored from (1) raw material pretreatment, for example, preheating limonite by microwaves to reduce the powder produced by bursting of its crystal water, or adding nano-coatings to enhance inter-particle bonding. Such processes have specific requirements on the raw materials and may increase process complexity and cost. (2) The cooling process is optimized, for example, the annular cooler is subjected to multi-section air quantity regulation so as to avoid the breakage of the sinter caused by thermal stress in the cooling process. Such methods focus mainly on the "end" treatment after sintering is completed. (3) Physical protection, for example, a buffer device is additionally arranged at a transfer point of a sinter conveying system so as to reduce mechanical pulverization caused by collision and drop. However, the above prior art have the common limitation that none of them do an effective and direct process intervention against the "sintering trolley edge air leakage" which is a fundamental problem in the sintering process. Because of the inherent gaps of the equipment, the air leakage of the edge area is serious, so that the effective air quantity of the area is insufficient, the thermal field is uneven, the sintering reaction is insufficient, and finally the produced edge sinter is low in strength and fragile, and becomes a main source of small size fraction. The existing method is focused on front-end raw materials or on rear-end treatment, and cannot systematically solve the problem of uneven quality of the sintering ore caused by air leakage at the edge from the core links (material distribution, ignition and air permeability equalization) of the sintering process. Disclosure of Invention In order to overcome the defects in the prior art, the invention provides a method for reducing the proportion of small size fractions of sinter. On the premise of not remarkably increasing equipment investment and process complexity, the proportion of small particle size grades (especially <5mm part) in the sintered ore product is systematically reduced, and the drum strength and the overall uniformity of the sintered ore are improved, so that higher-quality furnace burden is provided for a blast furnace, and the quality improvement and synergy of the sintering process are realized. In order to achieve the above purpose, the invention is realized by adopting the following technical scheme: the method for reducing the proportion of the small size fraction of the sinter comprises the following steps: (1) And (3) heightening the material layer at the edge part, namely lifting the height of the mixed material layers at the edge part areas at the two sides in the width direction of the sintering trolley to be higher than the height of the material layer at the central area, wherein the height difference delta H between the height of the material layer at the edge part and the height of the material layer at the central part meets the condition that delta H is more than or equal to 80mm and less than or equal to 150mm. (2) And (3) edge ignition strengthening, namely strengthening ignition is carried out on the edge material layer area after the height is increased in the step (1), the ignition intensity is higher than that of the central area, and the ignition temperature of the surface of the edge material layer is 20-150 ℃ higher than that of the central area. (3) The air permeability of the central area is regulated by adding an air permeability regulating material into a mixture in the central area of the sintering trolley, wherein the air permeability regulating material is at least one of lump ore, return ore powder or finished pellets, the adding proportion of the lump ore is 5% -15% bas