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Method for improving compressive strength of alkali pellets prepared with limestone

A technology of alkaline pellets and compressive strength, which is applied in the field of improving the compressive strength of pellets mixed with limestone, which can solve the problems such as the decrease of compressive strength of pellets, and achieve the effect of increasing oxidation and improving compressive strength

Active Publication Date: 2015-03-25
SHOUGANG CORPORATION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In order to solve the above technical problems, the present invention provides a method for improving the compressive strength of alkaline pellets mixed with limestone, which effectively overcomes the problem that the compressive strength of pellets decreases significantly after mixing limestone

Method used

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  • Method for improving compressive strength of alkali pellets prepared with limestone

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Comparison scheme
Effect test

Embodiment 1

[0023] Firstly, the limestone is ground to a particle size of 3 μm, and then the ultra-fine limestone powder is mixed into the concentrate powder with a particle size below 74 μm and an iron content of 86%, and the mass percentage is 8:92, and then mixed evenly after mixing. The moisture content of the mixture is controlled at 8.0%. Then carry out pelletizing in disc pelletizing machine, pelletizing time is 10 minutes. After pelletizing, sieve green pellets with a particle size of 8-16mm and dry them at 450°C for 7 minutes, then preheat at 650°C for 15 minutes, and enrich the oxygen during the preheating process, and keep the oxygen content at 14% , the preheated pellets were roasted at a temperature of 1260°C for 15 minutes, the oxygen content was controlled at 12% during the roasting process, and then soaked at a temperature of 1150°C for 3 minutes. After soaking, cool the pellets with air at room temperature to below 150°C to obtain alkaline pellets with a compressive stre...

Embodiment 2

[0025] Firstly, the limestone is ground to 2.5μm, and then the fine-grained limestone powder is added to the concentrate powder with a particle size below 74μm and an iron content of 85%. The mass percentage of limestone powder and concentrate powder is 3:97. Carry out mixing then, the moisture content of mixture is controlled at 7.8%.

[0026] The well-mixed material is pelletized with a disc pelletizer, and the pelletizing time is controlled for 10 minutes. Then use a sieve to sieve green balls with a particle size of 8 to 16 mm for roasting.

[0027] The roasting process includes drying, preheating, roasting, soaking and cooling. The prepared green pellets are first dried at 350°C for 7 minutes, and then preheated at 750°C for 15 minutes. During the preheating process, oxygen is enriched and the oxygen content is kept at 12%. The preheated pellets are heated at 1250°C Calcined at a temperature of 15 minutes, the oxygen content was controlled at 10% during the roasting pro...

Embodiment 3

[0029] Firstly, the limestone is ground to 2μm, and then the superfine limestone powder is mixed into the concentrate powder with a particle size below 74μm and an iron content of 80%. The mass percentage of limestone powder and concentrate powder is selected as 5: 95, then mix and add water, the moisture is controlled at 8.0%.

[0030] The well-mixed material is pelletized with a disc pelletizer, and the pelletizing time is 10 minutes. After pelletizing, use a sieve to sieve green pellets with a particle size of 8 to 16 mm for roasting.

[0031] The roasting process includes drying, preheating, roasting and cooling. The prepared green pellets are first dried at 400°C for 7 minutes, and then preheated at 800°C for 15 minutes. During the preheating process, oxygen is enriched and the oxygen content is kept at 14%. The preheated pellets are heated at 1250°C Calcined at low temperature for 15 minutes, the oxygen content was controlled at 11%, and the calcined pellets were soake...

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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...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22B1/00C22B1/16
Inventor 青格勒马丽田筠清马泽军刘洪松
Owner SHOUGANG CORPORATION
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