KR100309782B1 - Fabrication method of sintered ore using iron-laden dust generated during ironmaking process - Google Patents

Abstract

PURPOSE: A fabrication method of sintered ore is provided to prevent environmental pollution by recycling waste iron-laden dust after removing alkali and zinc from the iron-laden dust generated during ironmaking process. CONSTITUTION: The method is characterized in that after hazardous alkali and zinc are separated from blast furnace sludge and iron dust emitted from Dwight Lloyd sintering machine by wet cyclone, the blast furnace sludge and iron dust are added in raw material for sintering process in an amount of 0.5 to 1.0 wt.%.

Description

Sintered ore manufacturing method using steelmaking-generated dust

The present invention relates to a method for manufacturing a sintered ore as a raw material for steelmaking blast furnace using a DL (Dwight Lloyd) type sintering machine, and more particularly to the blast furnace sludge and sintered dust dust generated as waste resources in the blast furnace process and sintering process Sintered ore that efficiently removes harmful zinc and alkali components in the dust by wet cyclone treatment and recycles waste resources and improves sintering productivity and quality by using de-zinc and alkali-treated dust as sintering raw materials. It relates to a manufacturing method.

Generally, in the DL type sintering process, powdered iron ore, secondary raw materials, and powdered coke, which is a heat source, are put into a drum mixer, mixed and squeezed (raw material weight ratio of about 6-7%) to form a sintered blended raw material, which is made into a sintering machine. It is charged to a height, and the sintered compound raw material is fired by forcibly sucking air from below after surface ignition by an ignition furnace to produce a sintered ore.

In the granulation process of sintered blended raw materials, pseudo-particles are prepared by attaching fine particles of 1 mm or less around nuclear particles of 1 mm or more using moisture and binder (mainly quicklime, about 1.0-1.5% of total raw material). A method of increasing the particle size and decreasing the fine powder is used.

In addition, the sintering productivity is greatly influenced by the air permeability of the sintered blended raw material before the sintered blended raw material is ignited in the sintered trolley, and the air permeability is improved by improving the pseudo granulation of the sintered blended raw material.

The blast furnace sludge (approximately 5.6 tons / year: 96 records) generated in the blast furnace process is collected in a wet manner in the process of cleaning the flue gas discharged from the blast furnace, and contains a large amount of useful components (iron and carbon). many. However, due to the harmful components (especially zinc) contained in the blast furnace sludge, 69% of the generated amount cannot be recycled in the steelmaking process, and 31% of Nagi is sold as low-cost cement raw materials.

Zinc content in blast furnace charges causes lead damage and rust relief due to the formation of blast furnace wall attachments, which limits zinc content in the blast furnace industry to 0.1kg / T-p.

The blast furnace sludge contains about 36% and 31.4% of iron and carbon, and about 1.05% of zinc, a harmful component, and 60% of iron ore and 60% of coke with fixed carbon. It is an enormous potential resource worth 5.2 million tonnes.

In addition, in the sintering process, during the sintering process of the powdered iron ore, the flux and the powdered coke, dust is differentiated by the air flowing in at high speed or decomposed and evaporated at a high temperature to generate dust, which is dry collected in the electrostatic precipitator.

Sintered dust dust (generating amount of 140,000 tons / year: 96 records) is composed of extremely fine powder of less than 0.25mm, and the iron component of dust is about 40 to 50% by weight, mainly in the form of iron oxide and calcium ferrite. .

On the other hand, alkali compounds in dust are rapidly generated in the latter part of the sintering machine due to the structure of the sintering machine packed layer, and some of them are oxidized to exist in the form of K ₂ O, Na ₂ O, mainly KCl, NaCl, (K, Na) It is known to present about 10% by weight of dust in the form of water-soluble chlorides and lactates such as ₂ SO ₄ . It is also known that the alkali compound source in the sintered raw material is due to the alkali feldspar {(K ₂ O, Na ₂ O) Al ₂ O ₃ 6SiO ₂ } present in the iron ore gangue.

As such, when sintered dry dust dust with high alkali content and extremely fine powder is used directly as a steelmaking raw material, sinter productivity and reduction differentiation are deteriorated, sintering electric dust collection efficiency is deteriorated, sinter productivity is deteriorated due to deterioration of sinter productivity and formation of blast furnace wall attachments. Since it is a cause of over-exploitation, the current situation has been completely disposed of landfill, which is a cause of environmental pollution.

The present invention has been made to solve the problems of the prior art described above, blast furnace sludge and sintering generated as waste resources in the blast furnace process and sintering process in the production of sintered ore as a raw material for steel blast furnace using DL (Dwight Lloyd) type sintering machine The wet cyclone treatment removes dust and zinc, which are harmful components in dust, and recycles waste resources and improves sintering productivity and quality by using de-zinc and de-alkaline treated dust as sintering raw materials. Its purpose is to provide a sintered ore manufacturing method.

1 is a view schematically showing a wet classification treatment system used for wet classification of blast furnace sludge and sintered dust dust in the present invention.

The sintered ore manufacturing method using the steel-making iron-containing dust of the present invention for achieving the above object, when manufacturing the sintered ore as a raw material for the blast furnace blast furnace using DL (Dwight Lloyd) type sintering machine, resource recycling and sintering productivity and quality is improved In order to make blast furnace sludge and sinter dust collecting dust generated from waste resources in blast furnace process and sintering process with wet cyclone, it removes harmful components of zinc and alkali from dust, and de-zinc and de-alkaline treated dust is sintered raw material. To 0.5-1.0% level.

Hereinafter, the present invention will be described in detail with reference to the preferred embodiments.

In the present invention, the blast furnace sludge and sintered dust dust generated as waste resources in the sintering ore manufacturing in the sintering ore manufacturing process by the wet cyclone treatment to efficiently remove the zinc and alkali components of dust toxic components, de-zinc and de The sintering pot test was conducted to confirm the effect on the sinterability when using alkali treated dust as the sintering raw material.

The chemical composition of the blast furnace sludge and sintered dust dust used in the present invention is shown in Table 1, Zn of blast furnace sludge is 1.62%, Na ₂ O in the sintered dust dust, 0.16%, K ₂ O is 1.61% It was. Their particle size distribution is shown in Table 2.

division Chemical composition (% by weight) T.Fe FeO CaO SiO ₂ Al ₂ O ₃ MgO Na ₂ O K ₂ O C S Zn Blast furnace sludge 23.03 2.86 2.15 5.13 2.42 0.52 0.11 0.14 52.00 1.5 1.62 Sintered Dust 51.50 3.92 7.20 6.67 1.70 1.12 0.16 1.61 3.88 0.42 0.01

division Particle size distribution (% by weight) +0.25 mm +0.125 mm +0.10 mm +0.05 mm +0.025 mm -0.025 mm Blast furnace sludge 1.7 14.2 11.9 25.5 20.1 26.6 Sintered Dust Collector 2.4 5.6 15.3 31.2 17.5 28.0

Through the following examples will be described in detail the present invention.

Example 1

Table 3 shows the chemical composition of blast furnace sludge and sintered dust dust used in the present invention.

division Chemical composition (% by weight) T.Fe Na ₂ O K ₂ O C Zn High loss sludge +71 μm 26.0 - - 56.8 0.84 +36 ㎛ 27.9 34.3 1.56 + 20㎛ 37.6 26.1 2.94 -20㎛ 15.8 23.5 6.71 Sintered Dust +71 μm 41.7 0.04 0.18 - - +36 ㎛ 50.8 0.03 0.17 + 20㎛ 50.6 0.60 2.21 -20㎛ 44.2 1.26 4.36

In the case of blast furnace sludge, the zinc component is ubiquitous in the finely divided part of 20 μm or less, while the carbon component is ubiquitous in the granulated part of 20 μm or more.

Also in the case of sintered dust dust, Na ₂ O and K ₂ O components are localized in the finely divided part of 20 µm or less. In view of the fact that the zinc and alkaline components in the dust are unevenly distributed according to the particle size, the harmful components can be efficiently removed during the particle size classification process using a wet cyclone.

Therefore, in the present invention, a wet classification process using a wet cyclone was performed to efficiently remove zinc and alkali components of blast furnace sludge and sintered dust dust, and to recover dezinc and dealkali treated dust. 1 is shown.

In the wet classification process, as shown in FIG. 1, water, blast furnace sludge, and sintered dust dust are adjusted to about 15% of the concentration of mineral liquid in the stirrer 1 containing the mineral liquid 3, and the pressure gauge 4 is applied to the slurry pump 2. ) Was supplied to the installed wet cyclone (5) and the wet classification treatment, the equipment specifications and operating conditions of the wet cyclone (5) used in the present invention are shown in Table 4.

Item Specification and operating condition Wet Cyclone Dose 0.1 ㎥ / min Exterior 76 mm Supply pipe diameter 25 A Overflow Pipe Diameter 25 A Vortex Finder Diameter 20 mm Apex valve diameter 10 mm

The size of the wet cyclone (5) is cylindrical diameter 76mm, Apex valve diameter 10mm, Vortex finder diameter 20mm, mineral liquid supply pressure 2.0kg / ㎠ It was. The wet cyclone (5) is cylindrical in the upper part and conical in the lower part, and the mineral liquid is pushed through the sharpening port so that it can be rotated at a very high speed in the cylinder. The centrifugal force causes the granulated particles to descend to the cone by the centrifugal force. The particulates are ejected upward through the inner vortex finder.

The low zinc, low alkali dust (6) obtained through the above method was completely dried (105 ° C., 4 hours), and the content of zinc and alkali was examined by gravimetric and wet analysis. The recovery rates of low zinc, low alkali dust, dezinc and dealkali ratio were calculated by the following equation.

Recovery rate (%) = (underflow dust weight / pre-classified dust weight) × 100

● De-Zn, alkali rate (%) = [1- (Zn in alkali, alkali content / Zn in dust before classification, alkali content)] × 100

The chemical composition of the dust obtained after the wet classification treatment of blast furnace sludge and sintered dust dust by using a wet cyclone is shown in Table 5, and the de-zinc rate, de-alkali rate and recovery rate are shown in Table 6.

division Chemical composition (% by weight) T.Fe FeO CaO SiO ₂ Al ₂ O ₃ MgO Na ₂ O K ₂ O C S Zn Blast furnace sludge 25.23 2.76 2.23 5.30 2.38 0.60 0.07 0.09 52.2 0.39 0.14 Sintered Dust 56.1 4.31 6.33 6.60 1.55 1.12 0.07 0.10 2.07 0.06 0.01

division Dezincation rate (%) Dealkali rate (%) % Recovery Blast furnace sludge 88.5 - 72.5 Sintered Dust Collector - 93.3 70.0

After wet cyclone treatment, the blast furnace sludge decreased zinc content from 1.62% to 0.14%, resulting in 88.5% denitrification and 72.5% recovery.In case of sintered dust, Na ₂ O 0.16%, K ₂ O 1.61 % → Na ₂ O 0.07%, K ₂ O 0.09% was reduced to a de-alkali rate of 93.3%, recovery was 70.0%. In this embodiment, it was confirmed that blast furnace sludge and sintered dust dust can be efficiently removed from zinc and alkaline components during the wet classification process using a wet cyclone.

Example 2

In the present invention, the sintering test was performed to check the effect on the sinterability when using de-zinc and de-alkali dust obtained by wet cyclone treatment of blast furnace sludge and sintered dust dust.

The chemical composition and blending conditions of the sintered raw materials used in the present invention are shown in Table 7 and Table 8.

Sintered Fuel / Raw Material Chemical composition (% by weight) T.Fe FeO Al ₂ O ₃ SiO ₂ CaO MgO ironstone A 62.87 0.25 2.28 3.87 0.03 0.05 B 67.60 0.32 0.86 1.31 0.03 0.04 C 67.22 0.19 0.89 0.71 0.01 0.02 D 58.82 0.23 1.28 4.80 0.03 0.06 E 66.28 7.14 0.17 4.34 0.26 0.20 flux quicklime 0.29 - 0.37 1.08 83.49 3.55 Limestone 0.60 - 0.99 2.43 46.98 3.24 Serpentine 7.45 - 2.73 39.55 2.44 31.67 Quartz sand 0.93 - 3.19 96.20 0.76 0.17 Half light 56.24 8.42 1.75 6.17 9.74 0.19 Bunk coke 0.88 - 2.74 5.78 0.61 0.11

Sintered Fuel / Raw Materials Conventional example Inventive Example Mouth dildo Blast furnace sludge Sintered Dust Collector Iron ore and dust (%) ABCDE blast furnace sludge sintered dust dust 24.210.010.015.03.0-- 23.7 to 23.210.010.015.03.00.5 to 1.0- 23.7 to 23.210.010.015.03.0-0.5 to 1.0 -8 flux(%) Quicklime limestone serpentine 1.511.31.20.8 1.511.31.20.8 1.511.31.20.7 -1-3-1-1 Half glow (%) 19.2 19.2 19.2 -5 Bunkers (%) 3.8 3.8 3.8 -3 Sum 100 Target composition (%) SiO ₂ 5.46 MgO 1.40 CaO 9.91 Al ₂ O ₃ 1.85 Slag amount 18.6 C / S 1.82

Iron ore was used as three kinds of hematite spectroscopy (A, B, C), a hematite spectroscopy (D), and magnetite spectroscopy (E). Limestone, lime sludge, quicklime, serpentine, silica sand, and semi-ore were used as side materials, and buncoke was used as fuel. In addition, the compounding ratio of dezinc and dealkali dust was 0.5 to 1.0%.

In the sintering pot test, the sintered blended raw materials having the mixing conditions shown in Table 8 were uniformly mixed, loaded into a small drum mixer, mixed, added with water, and granulated. Was added.

The sintering pot used in this experiment was 200mm in diameter and 600mm in height. The assembled raw material was loaded with 3kg (30 ~ 35mm thickness) of top light first and loaded to the top of the pot. Was moved to the top of the pot for ignition (2 minutes), and at the same time as the ignition, the blower was operated to maintain the negative pressure at 1000 mmAq, and after ignition, the sintering was performed at a negative pressure of 1500 mmAq.

After sintering, the rotating strength (TI: Tumbling Index) drops once at 2m height and rotates 30 times at 24rpm in the tumbler tester. After crushing, the 15kg of the sintered ore of 10-50mm is put into the tumbler tester and rotated 200 times. It is expressed as a weight percentage of +6.3 mm sintered ore.

Reduction Degradation Index (RDI) of sintered ore was reduced by using 30g of 30% CO and 15Nl / min of N ₂ 70% at 550 ℃ using 500g of 15-20mm sintered ore. It was rotated at 30 rpm for 30 minutes and then expressed as a weight percentage of -2.83 mm sintered ore after crushing.

The reduction index (RI) of the sintered ore was reduced by using 500 g of 15-20 mm sintered ore at a temperature of 900 ° C for 120 minutes using 15 Nℓ / min of mixed gas of 30% CO and N ₂ 70%. Calculated by T.Fe and FeO content, the formula for calculating the rotational strength, reduction rate, low temperature reduction differentiation rate, sintering productivity and sinter recovery rate of sintered ore is as follows.

Table 9 shows the results of the sintering pot test according to the present invention.

division Conventional example Foot honor Blast furnace sludge Sintered Dust Collector 0.5% 1.0% 0.5% 1.0% Average particle diameter (mm) Wetting 3.69 3.73 3.83 3.75 4.11 dry 2.53 2.71 2.85 2.75 2.87 Average firing wind speed (m / s) 2.55 2.70 2.75 2.60 2.65 Sintering time (minutes) 34.8 34.4 34.2 34.0 33.5 Sintered Productivity (T / D / ㎥) 26.8 27.3 28.5 27.2 28.3 % Recovery 71.8 74.6 75.1 73.0 73.6 burglar(%) 77.9 78.5 79.1 78.3 78.8 Reduction Differentiation Rate (%) 43.7 43.0 42.5 43.5 42.2 Reduction rate (%) 75.5 76.5 75.3 75.5 75.1

As a result of adding 0.5-1.0% of de-zinc-treated blast furnace sludge, the sintered ore strength increased from 77.9% to 79.1% and the recovery rate from 71.8% to 75.1% compared to the conventional sintered ore manufacturing method. → improved to 28.5 (T / d / m ² ). The improvement of the strength and recovery rate of sintered ore is due to the fact that a large amount of carbon components (about 52.2%) contained in the dezinc-treated blast furnace sludge act as a supply heat source to increase the amount of fusion produced during firing. This is because the plastic breathability is improved by increasing the average particle diameter (3.69 → 3.83㎜).

Also, when 0.5-1.0% of de-alkali treated sintered dust was added, the sintered ore strength increased from 77.9% to 78.8%, and the recovery rate was increased from 71.8% to 73.6%, compared to the conventional sintered ore manufacturing method. Improved to 28.3 (T / d / m ² ).

As described above, according to the present invention, the blast furnace sludge and sintered dust dust generated as waste resources in the sintering process and the sintering process in the sintering ore manufacturing process by the wet cyclone treatment to efficiently remove the harmful components zinc and alkali components in the dust Use of de-zinc and de-alkaline treated dust as sintered raw materials can provide useful effects such as resource recycling and sintering productivity and quality.

Claims (1)

When manufacturing sintered ore as raw materials for steelmaking blast furnace using DL (Dwight Lloyd) type sintering machine, blast furnace sludge and sinter dust collecting dust generated from waste resources in blast furnace process and sintering process to improve resource recycling and sintering productivity and quality Sintered ore using iron-containing iron-containing dust, which is characterized in that it is treated with a wet cyclone to remove zinc and alkali components, which are harmful components in the dust, and de-zinc and de-alkaline treated dust is added to the sintered material at a level of 0.5-1.0%. Manufacturing method.

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