JPH10330851A - Formation of zinc-removed agglomerate from zinc-containing iron-making dust - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain sintered ore having low zinc content at high yield by specifying a packing height of dust and superficial gas flowing speed passed through a packing layer in a sintering machine and sintering zinc-containing iron-making dust. SOLUTION: At the time of producing the sintered ore for blast furnace by executing zinc-removal sintering to the zinc-containing dust produced in iron-making process of secondary ash in the blast furnace, fine granular dust in a converter, dust in an electric furnace, an upward suction type sintering machine is used to sinter these dusts into bulky state. In such a case, the raw material obtd. by mixing the fine grain dust in the converter and the secondary ash in the blast furnace to 1; 1 ratio, is packed to the height of 200-400 mm in the upward suction type sintering machine and the flowing speed of the air passed through the packing layer is regulated to <=0.4 Nm/sec to suck the air upward, and the zinc-removal sintering is executed. The zinc removing ratio of the zinc-containing dust in the raw material is drastically improved and the consumption of the sintered ore as the product in the blast furnace is drastically increased and recycled using ratio of the zinc-containing iron-making dust is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for dezincifying and agglomerating zinc-containing dust generated in an iron-making process such as secondary ash of a blast furnace, converter dust, and electric furnace dust by a sintering machine.

[0002]

2. Description of the Related Art Hitherto, as a method for dezincing zinc-containing iron dust, a reduction volatilization method using a kiln (Wurtz method) has been widely used. On the other hand, Japanese Patent Application Laid-Open No. 7-157829 concerning the method of blending the raw material dust, Japanese Patent Application Laid-Open No. 7-90395 regarding the particle size of the raw material, Japanese Patent Application Laid-Open No. 7-188786 regarding the ventilation gas composition and the calcination temperature, and the capture of coarse zinc oxide dust JP-A-9-41048 concerning a collecting method and JP-A-7-17-1 concerning a method for stabilizing firing.
No. 38661, JP-A-8-127821 and Japanese Patent Application No. 7-344379 disclose a dezincification agglomeration method using a sintering machine which is simpler, cheaper and more suitable for a location in a steelworks. ing.

[0003]

However, even in the above method, the dezincing rate (the ratio of the concentration of zinc in the raw material and the concentration of zinc remaining in the agglomerate after treatment to the zinc concentration in the raw material) is 5 to 5. In the case of a blast furnace with a strict zinc input limit of 70%, there was a case where there was still a restriction on the complete recycling of the agglomerate after treatment.

Therefore, an object of the present invention is to further reduce the residual amount of zinc in the agglomerated ore, increase the amount used in a blast furnace, and further promote the recycling of zinc-containing dust in steelworks.

[0005]

According to the present invention, there is provided a method for agglomerating zinc-containing iron dust using an upward suction type sintering machine, wherein the height of the packed bed of the dust is set to 200 to 400 mm, and the passing of the packed bed is performed. This is a method for dezincification of zinc-containing iron dust, characterized in that the hollow cylinder gas flow rate is 0.4 Nm / sec or less and suction is performed upward for firing.

According to the present invention, the best sintering conditions, that is, the best sintering conditions, ie, sintering, are used to ensure a sufficient high-temperature holding time of 1200 ° C. or more at which the reduction of zinc oxide by metallic iron in dust proceeds to promote the dezincification reaction. , The wind speed and the packed layer thickness conditions.

[0007] Zinc-containing iron dust refers to converter dust, blast furnace secondary ash, electric furnace dust, and mixtures thereof. Among them, the converter dust contains 10% or more of metallic iron from the viewpoint of promoting dezincification. In addition, the mixing ratio when mixing the electric furnace dust is preferably limited to 20% from the viewpoint of preventing a reduction in the amount of the reducing agent (metallic iron and carbon) in the mixture.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an upward suction type blower will be described. The agglomeration rate of the lower suction type blower and the upper suction type blower generally used in the iron ore sintering method in the raw material in which the converter fine dust and the blast furnace secondary ash are mixed at a ratio of 1: 1,
Table 1 shows the results of comparing the production rate and the dezincification rate. It can be seen that the upward suction type blowing can increase the dezincing rate by about 20% without changing the yield and the production speed. This is because, as shown schematically in FIG. 1, the sintering progress of the two is quenched while the melt generated in the melting zone is dropped onto the lower cold raw material layer in the case of the downward suction type. In contrast, in the case of the upper suction type, zinc oxide is formed by dropping on the previously formed lower lump and isolated from ventilation from the lower part, so that it is gradually cooled. This is because a high-temperature holding time of 1200 ° C. or more in which the reduction proceeds is sufficiently secured to promote the dezincification reaction.

[0009]

[Table 1] [Note] * 1) The time from the ignition start time to the time when the exhaust gas temperature reaches the maximum temperature. * 2) The burning progress rate calculated from the time when the thermocouple inserted into the sintered packed bed at 10 cm intervals shows the peak temperature.

[0010] In the upper suction type air blowing, since a large sinter cake mass is formed in the lower layer, the sintering of the upper portion to be subsequently fired is likely to be unstable, and the excessive layer thickness is caused by the unsintered portion in the upper portion. The dezincing rate as a whole decreases as a result. Therefore, in order to maintain a good zinc removal rate, it is necessary to properly control the layer thickness. FIG. 2 shows the effect of the layer thickness on the dezincing rate.
It can be seen that mm is the best.

Finally, regarding the passing cylinder gas flow velocity, when the passing cylinder gas flow velocity is reduced, as shown in FIG.
The dezincing rate is improved by increasing the high-temperature holding time and increasing the maximum temperature in proportion to the decrease of S (Frame Front Speed), and a high dezincing rate can be achieved at a flow rate of 0.4 Nm / sec or less.

[0012]

EXAMPLE A raw material consisting of 50% converter dust and 50% blast furnace secondary ash, and a circular table type sintering machine (effective sintering area 1)
The results of comparing the conventional method and the method of the present invention using m ² ) are shown. Table 2 shows the operating conditions and main operating results adopted in the conventional method and the method of the present invention. As the operating conditions of the conventional method, general conditions usually performed in iron ore sintering were adopted.

As a result of measuring the temperature in the sintered layer during firing, 1
The portion where the high-temperature holding time of 200 ° C. or more is secured for 2 minutes or more is about １ ／ of all layers in the conventional method,
It was confirmed that the method of the present invention covers almost all layers. As a result, the dezincing rate of the agglomerate ore, which was conventionally 50 to 60%, is 8
It was improved to 0% or more. Although the productivity slightly decreased with the decrease in the wind speed, the productivity was within an acceptable range.

[0014]

[Table 2]

[0015]

According to the present invention, the dezincing rate can be drastically improved. As a result, the amount of product agglomerate ore used in the blast furnace can be increased, and the recycling of zinc-containing dust in steel works can be further promoted.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing the progress of sintering of a downward suction type blow and an upward suction type blow.

FIG. 2 is a graph showing a change in a dezincing rate depending on the thickness of a filling layer.

FIG. 3 is a diagram showing a change in a dezincing ratio and the like depending on a flow velocity of a passing cylinder gas.

[Explanation of symbols]

 1 packed bed

Claims (1)

[Claims] 1. A method for agglomerating zinc-containing iron dust with an upward suction type sintering machine, wherein the height of the packed bed of the dust is 20 or less.
A method for dezincification of zinc-containing iron dust, wherein the pressure is 0 to 400 mm, and the gas flow rate of the hollow cylinder passing through the packed bed is 0.4 Nm / sec or less, and the powder is sucked upward and fired.