KR20030037748A - method of manufacturing the sinter reducing the Zn content - Google Patents

Abstract

The present invention mixes and assembles steelmaking sludge, blast furnace sludge, blast furnace dust catcher dust and quicklime, embeds sintered environment dust and quicklime and contains about 2-4% of quicklime and has a size of 4- The sintered ore manufacturing method which reduces the content of zinc in the sintered ore by producing and reacting mini-pellets of 6 mm is the main point.

Description

Sintered ore manufacturing method with reduced zinc content {method of manufacturing the sinter reducing the Zn content}

The present invention relates to a sintering and manufacturing method with a reduced zinc content, and in particular, a method for reducing Zn in the final sintered ore by removing Zn, which is one of the harmful elements, in recycling various by-products generated in the steelmaking process in the production of sintered ore. It is about.

In particular, the by-products generated in the steelmaking process in the present invention is manufactured in a mini-pellet (Mini-Pellet), but through the structural design to reduce the Zn content in the sintered ore.

In the steelmaking process, various kinds of gun dust and wet dust (sludge) are generated in each unit process. Recently, due to tightening regulations on environmental pollutants, the amount of dust generated by the expansion of facilities for collecting various dusts and the increase of dust collection efficiency is increasing. Generated dust is extremely fine powder with particle size of less than 1mm and contains a large amount of harmful components (Zn, S, Alkali, etc.), especially in case of gun dust, it causes secondary pollution due to dust scattering during transportation. Dust has a problem in handling because of its high moisture content.

However, since these dusts contain useful components such as iron and carbon, iron needs to be recovered, and carbon and low-cost iron oxides (Metal Fe, FeO, Fe 3 O 4) generate heat during combustion, and thus are expected to contribute as calories.

As mentioned above, these dusts contain a large amount of harmful elements, and among them, Zn is removed during sintering to reduce the Zn content in the final sintered ore.

When the Zn component is charged into the blast furnace due to its low volatility point (approximately 900 degrees), it volatilizes in the lower part but solidifies again in the upper part where the temperature is low, forming deposits in the furnace to change the flow of hanging and gas flows. It adversely affects and erodes the softening of the furnace furnace walls. Therefore, in a blast furnace using a large amount of sintered ore, Zn in the sintered ore should be managed as low as possible.

Conventional techniques for removing Zn components in dust include a method of removing dust in a rotary kiln and rotary hearth furnace (RHF) by reducing gas, and adding chloride (eg, CaCl _2, etc.). And baking at high temperature.

However, the above methods have the advantage of recovering the high purity Zn removed from the dust, while the operating temperature is high because the temperature in the furnace must be maintained at 1000 degrees or more, and the disadvantage of CO ₂ gas generated by the oxidation of the reducing gas. There is this. In addition, there is a method of blowing fine dust into the coke-filled layer through a tuyere, a method of using sensible heat of molten iron, and a method of leaching Zn using chemicals. There must be a water treatment plant.

In the method of reducing the Zn in the sintered ore during the sintering process, the current sintering process is ignited on the surface of the sintered layer by using an ignition furnace, and then sucked downward to produce Zn ore, and thus, Zn can be reduced by suctioning from the lower part to the upper part in the reverse direction. Although the results of the study have been reported, it is very difficult to suck up and down from the sintering machine structure that is currently used worldwide, and the equipment itself needs to be changed or supplemented.

The present invention has been made to solve the conventional problems as described above, by reducing the Zn content in the sintered ore by controlling the reaction mechanism by designing the structure of the particles during the production of dust-mini-pellet (Mini-Pellet) The purpose is to provide a way to.

Hereinafter, the present invention will be described in more detail.

In order to achieve the object as described above, mini-combined blast furnace sludge with high Zn content, steelmaking sludge and blast furnace dust catcher (D / C) dust with high C component and sintering environment (R-EP) dust In the manufacture of pellets (Mini-Pellet) and the structure of the various design and additives to improve the strength of the mini-pellets (Mini-Pellet), and the experiment was considered in consideration of the reaction mechanism.

Hereinafter, embodiments of the present invention will be described.

(Example)

Chemical compositions and compounding ratios of the various dusts used for this experiment are shown in Tables 1 and 2. And as an additive was used quicklime having a particle size of less than 1mm.

First, since dusts are extremely fine powders, when used in sintering in the form of powder, the air permeability of the sintered layer is deteriorated, thereby lowering the sintering productivity. Therefore, dust was prepared and used as a mini-pellet (Mini-Pellet). In terms of mini-pellets alone, the most important thing in sintering use is the strength of the mini-pellets. Therefore, in order to determine the strength according to the quicklime blending ratio of the mini-pellet, various dusts and quicklime ratios were varied and mixed, and then rotational strength was measured. In the experimental conditions, the particle size of the mini-pellets was fixed at 4-6 mm, and the quicklime mixture ratio was divided into 0, 2, 4, and 6%, respectively, and the preparation of the mini-pellets was performed using a pelletizer. The prepared mini-pellets were completely dried in a drying furnace at 100 ± 5 ° C. for at least 24 hours, and then placed in a tumbler having an inner diameter of 150 mm and a length of 200 mm, rotating at 900, and obtaining a ratio of 1 mm or less. The rotational strength of the mini-pellets according to the quicklime blending ratio is shown in Table 3.

Table 3 is a table showing the rotational strength of the mini-pellet quicklime blending ratio, the 2-4% quicklime blending ratio was found to be advantageous in terms of mini-pellet strength since the fraction of 1 mm or less after 900 rotations. In this experiment, the fraction (%) of 1 mm or less can be obtained as ((1 mm or less after 900 rotation (g) / gross weight of sample before rotation) × 100).

Meanwhile, various dusts (see Table 1) were mixed together and 2% of quicklime was mixed to prepare mini-pellets, and the content of Zn in the sintered ores according to the particle size of mini-pellets was investigated. Experimental equipment and conditions were used as a sintering test equipment (Sintering Test Equipment), as shown in Figure 2, because of the large amount of C and inexpensive iron oxide in the dust is expected to over-melt 3-5mm size to correct the calories Hematite was used together. Experimental conditions were charged while placing alumina balls up and down on the sintering simulation test tube and alternating mini-pellets and hematite in five layers, respectively. Ignition temperature was 1100 degrees. After sintering was completed, the sintered ore was crushed to 200 mesh or less to analyze the Zn content. The results are shown in Table 4.

The size of mini pellet was 4-6mm, the lowest Zn content in the sintered ore after sintering was 0.231%, and the removal rate was the lowest as 15.4%. Some studies have reported the reduction of Zn because the addition of metal Fe or C is advantageous in creating a reducing environment rich in CO gas. In other words, it can be said that the effect of reducing Zn increases when the reducing atmosphere is lengthened. For this reason, the Zn removal effect is reduced when the particle size is small (2-4mm) due to the rapid combustion rate. When the particle size is 6-8mm, the unbaked part exists inside the mini-pellet. It is judged that the volatilization of Zn was not easy due to the difference in thermal history at.

In the Zn reduction experiment according to the mini-pellet particle structure design, 4-6 mm size mini-pellets with 2% quicklime blending ratio were used.

The particle structure of the mini-pellet was divided into three types.

The first is a case of mixing and assembling various dusts and quicklime together, and the second is a combination of steelmaking sludge with high Zn content and blast furnace sludge, and a mixture of blast furnace dust catcher dust and sintering environment dust. The third case is the case where steelmaking sludge, blast furnace sludge and blast furnace dust catcher dust are embedded and the sintering environment dust is embedded.

In the present experiment, the Zn content in the sintered ore was 0.203% and the Zn removal rate was also high as 25.4% in Experiment 1 (B) compared to the comparative example (A). In general, Zn is removed by volatilization by the following reaction in a reducing environment.

ZnO (s) + CO (g) = Zn (g) + CO ₂ (g)

In order for the above reaction to occur, the amount of CO generated must be increased to create a reducing environment. To this end, it is necessary to lower the reactivity with oxygen by embedding C, which is the result of blast furnace sludge with high C content. On the other hand, Experiment 2 (C) had the lowest Zn content of 0.156% and the lowest Zn removal rate of 42.7%. This is also because the high C content of the blast furnace dust catcher dust is embedded together to further increase the amount of CO generated.

brand Compounding cost Steelmaking sludge 10.0 Blast furnace sludge 20.0 Blast furnace dust catcher dust 45.0 Sintered Environment Dust 23.0 quicklime 2.0

T.Fe FeO Metal fe SiO ₂ CaO Al ₂ O ₃ MgO Zn Steelmaking sludge 62.8 46.4 10.4 1.7 7.8 0.6 1.7 1.24 Blast furnace sludge 51.1 4.0 0.4 4.9 3.2 1.8 0.6 0.45 Blast Furnace D / C Dust 46.2 4.0 0.4 5.9 4.0 2.5 0.8 0.12 Sintered Environment Dust 49.2 1.7 0.05 or less 6.9 13.5 2.1 2.1 0.02

Quicklime Compounding Ratio (%) Fraction less than 1mm after 900 revolutions (%) 0 12.1 2 6.5 4 7.6 6 9.8

*% Fraction of 1mm or less = (weight of 1mm or less after 900 revolutions (g) / gross weight of sample before rotation) × 100

Particle size Zn content in sintered ore (%) Zn removal rate (%) 2-4mm 0.249 8.7 4-6mm 0.231 15.4 6-8mm 0.245 10.3

* Zn removal rate (%) = ((Zn content in sample before test-Zn content in sample after test) / Zn content in sample before test) × 100

Particle size Zn content in sintered ore (%) Zn removal rate (%) Comparative Example (A) 0.231 15.4 Experiment 1 (B) 0.203 25.4 Experiment 2 (C) 0.156 42.7

As described above, the present invention can reduce the Zn content in the sintered ore by stabilizing the blast furnace operation by removing the Zn which is one of the harmful components in the sintering process in recycling by-products generated in the steelmaking process, furthermore, such dusts There is an advantage in that it is possible to manufacture a sintered ore that is componently stable even in large amounts.

Claims (1)

Steel sludge, blast furnace sludge, blast furnace dust catcher dust and quicklime are mixed and assembled, and the sintered environment dust and quicklime are externally enclosed and contain 2-4% quicklime and 4-6mm in size Sintered ore manufacturing method characterized by reducing the zinc content in the sintered ore by producing and reacting pellets.