RU2567947C1 - Process line for production of iron ore pellets - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: line contains the furnace charge mixer for crude pellets, the furnace charge moistening system with nozzles, the furnace charge pelletiser for obtaining of crude pellets and the device for drying, screening, calcination and cooling of pellets, which are installed in process sequence and connected by vehicles. The line is fitted with the undersized coke batcher, the slack lime batcher and the batcher of slime and/or dust of gas purifications of domain, martin, converter or electrosteel-smelting productions or their mixes connected to the furnace charge mixer for green pellets. The furnace charge pelletiser for obtaining of green pellets is implemented in the form of dish-shaped granulator, the nozzles of furnace charge moistening system are located over the poppet of the dish-shaped granulator, the device for drying of pellets is implemented in the form of tape dryer, the device for screening of pellets is implemented in the form of the double-deck screen, the device for calcination of pellets is implemented in the form of the drum of calcination counterflow furnace, and the device for cooling of pellets is implemented in the form of the drum or mine refrigerator.

EFFECT: improvement of efficiency of recycling of metallurgical production.

3 cl, 2 dwg

Description

The inventive object relates to the field of preparation of raw materials for metallurgical redistribution and can be used in the production of iron ore pellets using sludge and / or dust from gas purification of a blast furnace, or open-hearth furnace, or converter, or electric steel-smelting production, or a mixture thereof.

The closest set of features to the claimed object is a pellet production line selected as a prototype, which contains a batch mixer for raw pellets installed in the technological sequence, a batch wetting system, a pelletizer for producing raw pellets, a device for drying, sieving, roasting and cooling the pellets. The raw material mixture mixer is adapted for mixing iron ore materials. The device for firing and cooling pellets is made in the form of a firing conveyor machine with technological zones for drying, heating, firing, recovery and cooling of fired pellets. In this case, the collector of the cooling zone is divided into three sections. A cooling agent with a temperature of 200-300 ° C is supplied to the first section, an agent with a temperature of 80-150 ° C to the second section, and outdoor air to the third section (RF Patent No. 2353676, published on 04.24.2012).

The claimed technological line for the production of iron ore pellets and the prototype have the following essential features. Both lines contain a batch mixer for raw pellets installed in a technological sequence and connected by vehicles, a batch wetting system, a pelletizer for producing raw pellets, and devices for drying, screening, roasting and cooling pellets.

Analysis of the technical properties of the prototype, due to its features, shows that the following reasons hinder the receipt of the expected technical result when using the prototype. In the production of iron ore pellets, such metallurgical wastes are not used, such as sludge and dust from gas blast cleaners, or open-hearth, or converter, or electric steel smelting, or a mixture thereof. In addition, the production of iron ore pellets does not capture such a valuable product as zinc concentrate, which contains zinc oxide.

The claimed object is based on the task of creating such a technological line for the production of iron ore pellets in which an improvement through the introduction of new elements would make it possible to use the inventive object to achieve a technical result consisting in increasing the efficiency of utilization of metallurgical waste by using such metallurgical waste in the production of iron ore production, such as sludge and dust gas blast furnace, or open-hearth o or converter or electric steel production or mixtures thereof. In addition, in the production of iron ore pellets, it is necessary to capture such a valuable product as zinc oxide, which is formed during the reduction of zinc, which is contained as an impurity in iron-containing sludges and dust from gas purifications.

The inventive iron ore pellet production line installed in a technological sequence and connected by vehicles, a batch mixer for raw pellets, a mixture wetting system, a pelletizer for producing raw pellets, a device for drying, screening, roasting and cooling pellets.

A distinctive feature of the claimed object is the following. The production line is equipped with a coke screener, slaked lime meter and a sludge and / or dust meter for blast furnace or open-hearth furnace or converter or electric steelmaking plants or their mixtures, which are connected by a vehicle to a charge mixer for raw pellets. The pelletizer for the preparation of raw pellets is made in the form of a plate granulator. The nozzles of the mixture wetting system are located above the plate of a disk granulator. A device for drying pellets is made in the form of a belt dryer. The device for screening pellets is made in the form of a two-screen screen. The device for firing pellets is made in the form of a drum firing countercurrent furnace, which is connected to a gas purification system equipped with bag filters. A device for cooling the pellets is made in the form of a drum or shaft refrigerator.

In particular cases, the claimed technological line for the production of iron ore pellets is characterized in that:

- nozzles of the mixture wetting system are located diametrically opposite above the plate of the disk-shaped granulator;

- the line is equipped with a ball mill for grinding screened pellets of substandard size and means for transferring the obtained powder to the mixture mixer for raw pellets.

By using the inventive iron ore pellet production line, a technical result is achieved consisting in increasing the efficiency of utilization of metallurgical waste due to the use of metallurgical waste in the production of iron ore pellets, such as sludge and dust from gas blast cleaners, or open-hearth furnaces, or converter or electric steel furnaces or mixtures thereof. In addition, the production of iron ore pellets ensures the capture of such a valuable product as zinc concentrate containing zinc oxide.

Between the totality of the essential features of the claimed object and the achieved technical result, there is the following causal relationship.

Supply of the production line with a coke screener, slaked lime meter and sludge and / or dust meter for blast furnace or open hearth furnace or converter or electric steel melting plants or mixtures thereof, which are connected by a vehicle to a charge mixer for raw pellets, pelletizing of the charge to produce raw pellets in the form of a plate granulator, the location of the nozzles of the mixture wetting system above the plate of a disk granulator, a device for drying pellets in the form of a tape drying apparatus, the implementation of the device for sifting pellets in the form of a two-sieve screen, the implementation of the device for firing pellets in the form of a rotary rotary kiln countercurrent kiln, which is connected to a gas cleaning system equipped with bag filters, the implementation of the device for cooling pellets in the form of a drum or shaft cooler provides high-quality iron ore pellets using metallurgical waste such as sludge and dust from blast-furnace or open-hearth gas cleaners, if the converter or electric steel production or mixtures thereof.

These iron-containing metallurgical wastes always contain zinc compounds. In the production of pellets from these iron-containing wastes of metallurgical production, zinc will be intensively sublimated and restored in the process of firing pellets, which is carried out at 950-1050 ° C. During the sublimation process, reduced zinc easily interacts with oxygen to form zinc oxide. The direction of the dusty gases containing zinc oxide exhausted from the kiln to the cooling and bag filters of the gas purification system ensures the collection and collection of such a valuable product as technical zinc concentrate containing zinc oxide.

In addition, the quality of iron ore pellets made from a mixture containing coke screenings, slaked lime and iron-containing material is improved, which is used as a slurry and / or dust from gas blast cleaners, or open-hearth furnaces, or converter or electric steel melting plants or a mixture thereof. The improvement in the quality of iron ore pellets is due to the following. If zinc is not removed from the pellets before they are loaded into the main production furnace units to produce cast iron and steel, metallic zinc sublimated from the charge can destroy the lining of the melting unit — a blast furnace, open-hearth furnace, converter, or electric furnace. In addition, zinc oxide deposits can form on the surfaces of the exhaust ducts, which complicates the operation of the exhaust ducts and their repair, shortens the overhaul period and increases the labor costs and the cost of repair work.

The location of the nozzles of the charge humidification system is diametrically opposite above the plate of the dish-shaped granulator, which means that at the maximum distance of one nozzle from the other, it provides more uniform moistening of the charge when pelletizing raw pellets, which move sequentially from the nozzle to the nozzle, while rolling around the surface of the dish-shaped granulator, which contributes to an increase in the yield of conditioned pellets due to improved adhesion properties of uniformly moistened components of the charge on the granule plate ilyator.

Equipping the technological line for the production of iron ore pellets with a ball mill for grinding screened pellets of substandard size and means for transferring the obtained powder to the mixer of the mixture for raw pellets allows the maximum use of metal-containing waste from metallurgical industries, such as sludge and dust from gas purification in collecting and collecting such a valuable product, as a technical zinc concentrate containing zinc oxide.

The essence of the claimed object is illustrated by graphic materials, which depict:

in FIG. 1 is a block diagram of a production line for the production of iron ore pellets;

in FIG. 2 is a plan view of a plate granulator plate.

The following notation is used on the graphic materials presented:

1 - batch mixer for raw pellets;

2 - coke screening dispenser;

3 - slaked lime dispenser;

4 - dispenser of iron-containing material;

5 - charge moistening system;

6 - plate granulator;

7 - a device for drying pellets;

8 - a device for sifting pellets;

9 - ball mill;

10 - device for firing pellets;

11 - gas cleaning system;

12 - a device for cooling pellets;

13 - nozzle;

14 - nozzle;

15 - plate;

16 - charge feeder;

17 - removable knife.

In a specific exemplary embodiment, the iron ore pellet production line comprises devices installed in a technological sequence and connected by vehicles. Above the batch mixer for raw pellets 1, a coke screener 2, slaked lime batcher 3 and iron-containing material batcher 4 are installed, which are connected by a vehicle to the batch mixer for raw pellets 1. Next, a charge moistening system 5, a plate granulator 6, and a device for drying pellets are installed 7, a device for sifting pellets 8, a ball mill 9, a device for firing pellets 10, a gas cleaning system 11 and a device for cooling pellets 12.

The mixture mixer for raw pellets 1 is adapted to mix screenings of coke, slaked lime and iron-containing material, which is used as a slurry and / or dust from gas purification blast furnace, or open-hearth furnace or converter or electric steel production or a mixture thereof.

The pelletizer for producing raw pellets is made in the form of a dish-shaped granulator 6. In this case, the nozzles 13 and 14 of the moistening system of the charge 5 are located diametrically opposite over the dish-shaped granulator 15 between the charge feeder 16 and the removable knife 17.

A device for drying pellets 7 is made in the form of a belt dryer. A device for sifting pellets 8 is made in the form of a two-sieve screen. A device for firing pellets 10 is made in the form of a drum rotating firing countercurrent kiln, which is connected to a gas cleaning system 11, equipped with bag filters. A device for cooling the pellets 12 is made in the form of a drum refrigerator.

In a specific example, the production line of iron ore pellets works as follows.

For the charge, components are used, in particular, screenings of coke and slaked lime, with a particle size not exceeding 300 microns.

In a specific example, a mixture of blast furnace gas treatment sludge, production and open-hearth dust, converter and electric steelmaking is used as the iron-containing material. Sludge gas treatment blast furnace, production pre-dried up to 16 wt.%. For the iron-containing material used, the total amount of iron and zinc in it is determined. For example, in this iron-containing material, iron is 56.75 mass%, zinc is 3.32 mass%, and in total 60.07 mass%. This means that 100.07 kg of iron-containing material contains 60.07 kg of iron and zinc. In this case, the screening amount of metallurgical coke for the charge is taken to be 1.3 times greater than the total amount of iron and zinc in the iron-containing material, i.e. 60.07 × 1.3 = 78.09 kg. The total amount of iron-containing material and screenings of metallurgical coke is 100.00 + 78.09 = 178.09 kg. The amount of slaked lime used as a binder is 0.16 of the total screening of metallurgical coke and iron-containing material, i.e. 178.09 × 0.16 = 28.5 kg. In this example, when preparing a mixture for raw pellets in a mixer, 100.00 kg of iron-containing material, 78.09 kg of sifting of metallurgical coke and 28.5 kg of slaked lime should be mixed.

The components of the charge in the required quantity are loaded into the batch mixer for raw pellets 1 through weight batchers: coke screener 2, slaked lime meter 3 and iron-containing material 4. In a hermetically sealed mixer, the mixture for raw pellet 1 mixes coke screenings, lime and iron-containing material. The resulting mixture is sent to a disk granulator 6. On a plate 15 of a disk granulator 6, the lumps of the mixture fall from the dispenser 16. Above the plate 15, water is sprayed to the mixture through the diametrically arranged nozzles 13 and 14 of the charge moistening system 5 to moisten the charge to a moisture content of 12-16 wt.%. On a dish-shaped granulator 6, the mixture is pelletized to obtain raw pellets, which are removed from the plate 15 with a removable knife 17.

The obtained pellets are dried in a belt dryer of the device for drying pellets 7 at 200 ° C for 2 hours. Then, on a two-screen screen in the device for sieving pellets 8, sieving of dry pellets is carried out into fractions of conditioned and substandard pellets in size. Conditioned pellets are sent for firing into a rotary rotary firing countercurrent kiln of a device for firing pellets 10. The pellets are fired at 1000 ° C. for 2.5 hours. Dusty gases containing zinc oxide leaving the kiln are sent to the gas cleaning system 11 to collect zinc concentrate in bag filters. In the gas cleaning system 11, the dusty gases in front of the bag filters are cooled to an acceptable value by suction of atmospheric air into the gas duct through a control valve.

The calcined metallized iron ore conditioning pellets are cooled in a drum refrigerator of a device for cooling pellets 12.

The sieved pellets of substandard size are crushed in a ball mill 9 to particles whose size does not exceed 300 microns. The resulting powder using a conveyor is transferred as an additive to the mixture in the mixer of the mixture for raw pellets 1.

When the zinc content in the iron-containing material is less than 1 wt.%, Sieving of dry pellets on a two-sieve screen before firing is carried out to a size of 3-20 mm. And conditional pellets of 3-20 mm in size are sent for firing.

When the zinc content in the iron-containing material is more than 1 wt.%, The sieving of dry pellets on a two-sieve screen before firing is carried out to a size of 3-10 mm for a more complete extraction of zinc from the deep layers of the pellets during firing.

Technical zinc concentrate collected from bag filters of the gas treatment system 11 contains 72-75% zinc oxide.

Claims (3)

1. A technological line for the production of iron ore pellets, comprising a charge mixer for raw pellets installed in a technological sequence and connected by vehicles, a humidification system of a charge with nozzles, a pelletizer to produce raw pellets and a device for drying, screening, roasting and cooling pellets, characterized in that it is equipped with a coke screener, slaked lime meter and a sludge and / or dust meter for gas treatment of blast furnace, open-hearth, converter or electric steel production plants or mixtures thereof, connected by a vehicle with a batch mixer for raw pellets, wherein the pelletizer for producing raw pellets is made in the form of a plate granulator, the nozzles of the charge moistening system are located above the plate of a granulator, the device for drying pellets is made in the form of a belt dryer, the device for screening pellets is made in the form of a two-screen screen, the device for burning pellets is made in the form of a drum firing countercurrent furnace connected to systems th gas purification equipped with bag filters, and for cooling pellets device is a silo or drum cooler. 2. The production line according to claim 1, characterized in that the nozzles of the mixture wetting system are located diametrically opposite above the plate of the disk granulator. 3. The production line according to claim 1, characterized in that it is equipped with a ball mill for grinding screened pellets of substandard size and means for moving the resulting powder into a batch mixer for raw pellets.

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