Sintering operation procedures, sintering process

Sintering: It is the process of mixing various powdered iron-containing raw materials, mixing with an appropriate amount of fuel and flux, adding an appropriate amount of water, and making a series of physical and chemical changes in the material on the sintering equipment after mixing and balling, so as to bond the mineral powder particles into a lump.

But it seems that they were all found somewhere.

The first floor of the process is the correct solution.

Sintering is a method of heating powdery materials (such as fines and concentrates) at high temperatures to sinter them into lumps under incomplete melting conditions. The resulting product is called sinter and is irregular and porous in shape. The heat energy required for sintering is provided by the carbon in the sintered material and the excess air through combustion, so it is also called oxidative sintering.

Sinter mainly relies on liquid phase bonding (also known as melt sintering), and solid-phase bonding plays only a minor role.

Modern sintering production is a kind of exhaust sintering process, the mixture (iron ore powder, fuel, flux and ore return) with an appropriate amount of water, mixing, granulating, spread on the grate of the belt sintering machine, after ignition with a certain negative pressure pumping, so that the sintering process from top to bottom. The sinter is unloaded from the sintering trolley, crushed, cooled, granulated, screened, and the finished sinter, returned ore and bottom material are separated.

The typical sintering production process can be divided into 8 process systems:

1) The receiving process system mainly includes the dumper system, the receiving trough, the concentrate warehouse, the flux warehouse, the combustion warehouse, etc., and its task is to be responsible for the acceptance, transportation and storage of incoming raw materials.

2) The raw material preparation process system includes the neutralization of ferrous raw materials, the crushing of fuel, the crushing and screening of flux, and its task is to prepare raw materials, fluxes and fuels that meet the production requirements for the batching process;

3) The batching process system includes the ore trough between the batching room, the disc feeder, the weighing facility, etc.; According to the specified sinter chemical composition and the type of raw materials used, each raw material is fed according to the calculated weight through calculation, so as to ensure the stability of the chemical composition of the mixture and sinter and the adjustment of fuel quantity.

4) The mixing and granulation process system mainly includes cold and hot ore return to the disc, and one-time mixing; Mixing material trough, secondary mixing and other processes. Its task is to add water, wet the mixture, and then use a mixer to mix the mixture, and the secondary mixer preheats the balls.

5) The sintering process system includes primer, cloth, ignition, sintering, etc. The main task is to sinter the mixture into a qualified sinter.

6) The exhaust process system includes a bellows, dust collection pipes, dust collectors, and patting fans. chimneys, etc.

7) The finished product processing process system includes hot crushing, hot screening, cooling, cold crushing, cold screening, and finished product transportation system. The task of this process is to separate: 5 50 mm of finished sinter, 10 20 mm of primer, less than 5 mm of cold return.

8) The environmental protection dust removal process system is mainly to use the electric precipitator system to unload the tail of the sintering machine, hot screen, cooling, ore return and the exhaust gas of the dust point of the whole grain system, after the dust collector purification, the exhaust gas is discharged into the atmosphere, and the dust is added to the sintering mixture after wetting and then sintered. Its mission is to protect the environment in sintering production.

In some sintering plants in China, the process is not perfect, and some have no cooling, cold crushing, and cold screening operations (called hot ore plants); Although some have cooling, they do not have the function of cold breaking, cold sieving and bottoming. In the more advanced Baosteel sintering process, the raw material is accepted and the flux is crushed, screened and neutralized in the raw material yard, and the iron-containing raw material is mixed into a single chemically stable mixture directly to the sintering batching tank.

Sintering machine system: including raw fuel input, batching, mixing, sintering, crushing, screening, and priming.

The flow chart of the sintering process is shown in the attached drawing.

Brief description of the sintering process:

1) Raw material preparation and batching.

Sintering raw materials include ferrous raw materials (raw ore and concentrate fines), fluxes (quicklime, limestone), fuels (coke or anthracite), additives (steel scales, steel plant dust) and ore return. In addition to a certain chemical composition, these raw materials also require a certain chemical composition stability.

After mechanical forced mixing, the material forms small balls of different particle sizes, so that the material has good air permeability.

The addition of ore return is conducive to increasing the air permeability of the mixture.

2) Mixed Fabric:

Mix and granulate all kinds of powder to ensure that the quality of the sinter is relatively uniform, add the necessary water in the mixing process to fully moisten the sintered material, so as to improve the air permeability of the sintered material, we use the secondary mixing process, in the first mixing is mainly to mix well and add appropriate water to moisten, and the secondary mixing is supplemented to the appropriate moisture to make the fine powder in the mixture cause small balls.

The wide belt feeder is used to evenly distribute the material along the width of the trolley to ensure consistent air permeability, and at the same time ensure that the material surface is flat and has a certain looseness.

3) Ignition control.

The materials on the sintering trolley are ignited on the material surface through the ignition furnace, and the sintering starts from the material surface, and the fuel mixed in the mixture is burned from top to bottom to achieve the purpose of sintering under the condition of forced ventilation. The ignition furnace is ignited by blast furnace gas, which saves the energy consumption of the sinter and reduces the cost.

4) Treatment of sinter:

The sinter is crushed and screened, so that the sinter particle size is uniform and part of the raw material is removed, so as to create favorable conditions for blast furnace smelting, and the sieve is double-layer screen, of which the less than 6mm is used as the return ore into the batching, 6-20mm as the bottom material, and more than 20mm into the blast furnace silo.

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Flaring, batching, mixing, sintering, cooling, finished product screening.

Raw materials: 1. Iron-containing raw materials, ore powder with high iron content and particle size greater than 5 mm, iron concentrate, blast furnace dust, steel scale, steel slag, etc.;

2. The flux requires a high content of effective CAO in the flux, less impurities, stable composition, about 3% water content, and more than 90% of the particle size less than 3 mm. A certain amount of dolomite is added to the sinter material to make the sinter contain appropriate MGO, which has a good effect on the sintering process and can improve the quality of the sintering source.

3. Fuel, mainly coke powder and anthracite. The requirements for fuel are high fixed carbon content, low ash content, low volatile matter, low sulfur content, stable composition, water content less than 10%, particle size less than 3 mm accounting for more than 95%;

Ingredients & Mixing:

1. Batching, batching purpose, to obtain sinter with stable chemical composition and physical properties, to meet the requirements of blast furnace smelting;

2. Mixing, mixing purpose: to make the composition of the sintered material uniform, suitable moisture, easy to ball, so as to obtain a sintered mixture with good particle size composition, in order to ensure the quality of the sinter and improve the output, mixing operation, water wetting, mixing and balling. According to the different properties of raw materials, two processes can be used: primary mixing or secondary mixing.

The purpose of a mixture, wetting and mixing, when heating and returning to ore, can also make the material preheated. For the purpose of secondary mixing, continue to mix and pellet to improve the air permeability of the sintered material layer.

The process flow of sintering production.

At present, belt extraction sintering machine is widely used in production to produce sinter. The process flow of sintering production is shown in Figure 2-4. It mainly includes the preparation of sintered materials, batching and mixing, sintering and product processing.

Exhaust sintering process.

Preparation of sintered raw materials.

Iron-containing raw materials. Ore powder with high iron content and particle size of <5mm, iron concentrate, blast furnace dust, rolled steel scale, steel slag, etc.

Generally, iron-containing raw materials are required to be of high grade, stable composition and less impurities.

Flux. It is required that the effective CAO content in the flux is high, the impurities are less, the composition is stable, the water content is about 3, and the particle size is less than 3mm, accounting for more than 90.

A certain amount of dolomite is added to the sinter material to make the sinter contain appropriate MGO, which has a good effect on the sintering process and can improve the quality of the sinter.

Fuel. Mainly coke powder and anthracite.

The requirements for fuel are high fixed carbon content, low ash content, low volatile matter, low sulfur content, stable composition, water content less than 10, and particle size less than 3mm, accounting for more than 95.

General requirements for raw materials for incoming knots.

Ingredients & Mixing:

Ingredient. The purpose of batching: to obtain sinter with stable chemical composition and physical properties to meet the requirements of blast furnace smelting.

Commonly used batching methods: volumetric batching method and mass batching method.

The volumetric batching method is based on the condition that the bulk density of the material remains unchanged and the mass of the raw material is proportional to the volume. Poor accuracy.

The quality batching method is based on the quality of the raw materials. The specific volume method is accurate and easy to automate.

Mix. Mixing purpose: to make the composition of the sinter uniform and suitable moisture, easy to pelletize, so as to obtain a sinter mixture with good particle size composition, so as to ensure the quality of the sinter and improve the output.

Mixing operation: add water to moisten, mix and pelletize.

Depending on the nature of the raw materials, two processes can be used: primary mixing or secondary mixing.

The purpose of a mixture, wetting and mixing, when heating and returning to ore, can also make the material preheated.

For the purpose of secondary mixing, continue to mix and pellet to improve the air permeability of the sintered material layer.

When sintering with rich ore powder with a particle size of 10 omm, because its particle size has reached the need for pelletizing, a mixing time of about 50s is used.

When sintering with finely ground concentrate powder, because the particle size is too fine, the air permeability of the material layer is poor, in order to improve the air permeability, it is necessary to make balls in the mixing process, so the secondary mixing is adopted, and the mixing time is generally not less than 2 5 3min.

On this basis, in order to achieve the stability of raw material conditions and reduce the standard deviation of silica and iron grades in raw materials, a raw material mixing process (i.e., pre-batching) is added before batching, and the sintering process can increase the process of laying the bottom material, using hot air sintering and double-layer material knot to improve the reaction heat effect in the sintering process, improve the physical and chemical properties of sintering by improving the phase change in the reaction process, and reasonably select different sizes of sieves in the cooling and classificationFirst, it can classify part of the bottom material, and secondly, it can create good conditions for the grading of the next process.

The batching method, the weight batching method that is basically used at present, uses electronic scales to achieve the purpose of automatic control, and the central control room specifically operates the given value of each material under different proportions. In the batching process, the current hot spots and difficulties are: the digestion of quicklime and the removal of dust in its area.

An important step. PTFE preforms must be sintered to become a useful product. Sintering is to heat the preform to above the melting point (327) and hold it at this temperature for a certain period of time, so that the polymer molecules gradually change from crystalline shape to amorphous, so that the dispersed resin particles are bonded into a continuous whole through mutual melting and diffusion.

The sintered preform is cooled from a transparent colloidal body into a strong, milky opaque product.

The sintering process refers to the processing program and sintering process system selected according to the characteristics of the raw materials. It has a direct and important impact on the yield and quality of sintering production. This bright process selects the appropriate process flow and operation system according to the internal law of the sintering process, and uses the scientific and technological achievements of the current generation to strengthen the sintering production process, which can obtain advanced technical and economic indicators to ensure high yield, high quality and low consumption.