UA5198U - A mechanism for blowing metal with gases - Google Patents

Abstract

A mechanism for blowing metal with gases contains working layer of refractory material, linear gastight zones. The mechanism is made of monolith refractory concrete in the form of a block with gastight linear zones with thickness of no more than 2 mm, diameter of capillaries of 0.2-0.3 mm and distance between them of 1.0-2.0 mm and distance between zones of 20-40 mm.

Description

A useful model refers to the field of metallurgy, in particular to the refining of liquid metal with gases in a metallurgical vessel.

A known device for blowing metal containing a lined ladle, in the bottom of which a porous insert made of refractory material is installed (AS USSR, Me349729, M.Kl.2 С21С 7/00, 1970, | However, blowing through a porous insert, which is proposed in the known device, it is not very effective, due to its low resistance when in contact with molten steel.

A well-known device for blowing metal (A.S. USSR Mo532478, M.Kl.2 C21С 7/00, 1977 | holding a porous insert embedded in the lining of the bottom of the ladle to a depth of 0.01-0.25 of the thickness of the lining. The recess is filled with refractory mass with a gas permeability coefficient of 15-90 nanopores and an area of 1.5-20 areas of the porous insert.

The known device has disadvantages: - with the existing trend in the metallurgical industry of introducing linings made of refractory concrete, the resistance of which is significantly superior to linings made of bricks, the use of porous fillings with relatively low resistance (4-6 pours) is not technological. To replace the porous refractory mass, it is necessary to cool the container (approximately 8-16 hours), clean the worn mass and stuff a new one (approximately 3 hours), warm up the ladle (10-12 hours), the full cycle of repairing the porous insert is from 21 to 36 hours. The durability of concrete is equal to the order of pours, that is, 9-12 repairs, which in terms of time is 100-200 hours (4-9 days). With modern technologies of working with a hot ladle, the ladle cycle is up to 10 pours per day, therefore, when using a known device, the ladle is set aside for repair every 12-14 hours. This makes it necessary to increase the fleet of buckets by 2 times.

Therefore, the use of the known device is not profitable; - currently, to increase the stability of the lining of the bottom of the bucket, hot intermediate repairs are used, which consist in the restoration of worn areas of the lining with the help of shotcrete or pouring with fire-resistant non-porous concrete. The use of the known device with this technology of intermediate repairs is impossible because the porous refractory mass will be monolithized and will lose its functional capacity; the throughput of porous plugs and inserts is no more than 1.3 m3/min, at a pressure of more than wattm. However, the necessary gas consumption to obtain tangible results is more than 0.3 m3/ per ton of steel. For conditions of use 150t. steel ladle, the total minimum gas consumption will be 150-0.3-:45m3, which will take 36 minutes of purging. This duration of purging is technologically impossible without the use of special measures (intermediate heating by overheating the metal at the outlet). In addition, increasing the residence time of the liquid metal in the ladle significantly reduces its stability and increases the time of the technological cycle, which leads to the need to increase the fleet of ladles and, ultimately, the cost of the smelted metal.

The closest in terms of technical essence is a ladle for blowing metal with gas (Patent Mo49775 Metallurgical container for processing molten metal with gas) a metal casing that includes wall and bottom lining. The lining of the bottom consists of a reinforcing layer and a working layer. Between them is a gas distribution cavity with a supply fitting. Above the gas distribution cavity is a working layer of brickwork with gas-permeable seams.

The disadvantage of such a bucket is the mandatory use of refractory bricks in the area of the blowing zone.

The use of refractory bricks means the use of a refractory gas-permeable solution. Masonry and service properties of the mortar depends on many reasons: fractional composition, ratio of viscous components to the main fraction, ratio of fractions, microadditives of plasticizers and floaters. One of the main reasons is the amount of water in the solution. On the one hand, the increase in water leads to an increase in plasticity, which causes better filling of seams. On the other hand, an increase in water leads to a decrease in the strength of the resulting seam. During drying, there is excessive shrinkage of the solution, the formation of shrinkage cracks and looseness, which unpredictably distorts the shape and dimensions of the exit of gas channels, therefore, unpredictable gas permeability and the type of gas flows exiting the melt. In addition, the appearance of cracks will lead to slagging and metallization of seams and will unexpectedly change the gas permeability of seams. In addition, the quality of masonry depends significantly on subjective reasons: the mason's qualification, the quality of the preparation of the material for masonry, the filling of seams, the beginning or end of the shift, whether the masonry is done in one shift or with a change, etc. The next disadvantage is the impossibility of obtaining the necessary configuration of the blowing zones due to the rectangularity of the bricks used in laying the flat bottoms of metallurgical containers, for example, a steel ladle. When restoring the worn lining of the bottom by the method of pouring fire-resistant concrete, with minimal porosity, there is a complete loss of gas permeability of the seams of the working area and loss of functional purpose. Currently, there is an active application of technologies for the production of monolithic linings from refractory concrete. The durability of the lining made of concrete is much higher than that of brick. Therefore, the use of bricks leads to uneven wear of the lining of the bottom, and the use of high-refractory concrete loses its meaning due to the anticipatory wear of bricks (the durability of concrete is at least 40 pours, and for bricks this indicator is no more than 15). Repair of brickwork with gas-permeable seams requires complete cooling of the container, knocking out the remains of the masonry, clearing and laying new bricks with gas-permeable seams. After finishing the work, they dry and warm up the containers. The duration of the production cycle of repair works is from 24 to 36 hours. It is necessary to make three intermediate repairs of the blown zone for one bucket made of a monolithic lining made of refractory concrete. In addition, the service properties of monolithic linings significantly depend on the temperature difference. Each cooling leads to the appearance of microcracks and a violation of the integrity and strength of the refractory, therefore, its service life.

The distance between the seams of the brickwork is mainly 80mm along the thickness of the brick and 300mm along its length.

Studies on transparent models have shown that such distances between gas-permeable seams are overestimated by approximately 2.5 times. That is, the gas flow is too loose, the ratio of the working volume of gas to the volume of the processed melt decreases in the cubic degree, therefore the cycle time of mass transfer processes increases sharply.

Anticipatory wear of brick masonry compared to monolithic masonry leads to the formation of depressions and potholes in the plane of the bottom or metallurgical container. This leads to the fact that washouts appear on the surface of the gas-permeable zone, in which the solidified metal will form a floor, which leads to the termination of the functioning of the blowing device. In addition, reducing the thickness of the masonry in the area of the blowing zone leads to faster heat removal, which in turn contributes to the freezing of metal and slag on it

The useful model is based on a technical task: increasing the efficiency and reliability of the blowing device with compliance with the conditions of stability of the lining of the entire bottom of the metallurgical container, reducing the production time of repair works, as well as increasing the specific gas permeability of the working area.

The essence of the useful model is that the device containing the working layer of refractory material, linear gas-permeable zones is made of monolithic refractory concrete in the form of a block with gas-permeable linear zones no more than 2 mm thick, the diameter of capillaries 0.2-0.3 mm and the distance between with them 1.0-2.0 mm and the distance between zones 20-40 mm.. It can have a collector layer 20-30 mm thick. made of concrete of the same composition as the working layer, but additionally diluted with 5095 refractory crushed stone with a fraction of 5-15 mm. The device can be made in the form of a truncated pyramid with the aspect ratio: lower base 1; height 1; upper 0.52 and 120-200 mm thick. or in the form of a parallelepiped with a ratio of sides that is a multiple of refractory artificial brick

Common features of the useful model with the prototype are: - working lining of the bottom of the metallurgical container; - working layer with linear gas-permeable areas; - collector gas distribution layer.

Distinctive from the prototype are: - monolithicity of the blowing section of the device; - absence of masonry seams; - reducing the distance between blowing zones; - projected dimensions and location of capillaries for the exit of gas into liquid metal; - uniform strength of the lining of the device and the entire bottom of the metallurgical container.

The set of essential features are necessary and sufficient for all cases covered by the scope of the proposed device for blowing metal with gases.

Between the essential features of a useful model and the technical result - the use of refractory concrete for the manufacture of blocks of a certain shape, with a certain arrangement of blowing zones and precisely located capillaries of a given size for blowing metal with gases - there is a causal - investigative relationship, which is established when describing the design of the device and his works.

The useful model is explained by the drawings, which show the devices in plan with the pointers of the porous zones, as well as the cross-section with the pointers of the working and gas distribution layers.

The device is made of refractory concrete in the form of a monolithic block, with a gas distribution layer, and linear gas-permeable areas.

Gas-permeable linear sections are a discontinuous or continuous strip 1.5-2.0 mm wide with the best location perpendicular to the axis of symmetry of the block and the distance between them is 20-40 mm

In Figure 1, the block for blowing metal with gases is represented by a two-layer plate 1.

Gas-permeable rows are located in the form of non-intersecting linear sections 2, which represent a system of 1.5-2.0 mm thick vertical capillaries through the thickness of the block. The distance between rows is 20-40 mm.

The block is made of refractory mass, from which the lining of the bottom of the metallurgical container is made.

For uniform distribution of gas under the block, a second layer C is located below the block, which performs the function of a gas distribution manifold. The thickness of the collector layer is 20-30 mm. (see Fig. 3). The collector layer is made of diluted, approximately 5095, refractory crushed stone with a fraction of 3...15 mm. refractory concrete.

Distances between rows of 20-40mm are determined by the following considerations when reducing the distance to less than 20mm. the gas flow does not cause a noticeable increase in mass transfer processes; moreover, an excessive increase causes bubbling of the metal mirror and, as a rule, its exposure. At the same time, a number of undesirable processes develop, and the main ones are intensive secondary oxidation, increased and unpredictable carbon dioxide emissions, large heat losses, and high-speed flows accelerate the erosion of the lining. A blurred lining contaminates the metal with non-metallic inclusions. In addition, when making such blocks, the distance between rows of capillary formers is less than 20 mm. significantly complicates the technology of laying and uniform compaction of refractory concrete, therefore, the factor of obtaining a low-quality refractory block increases.

When the distance between the rows is more than 40 mm, the gas flow is loosened too intensively, this leads to the fact that the number of bubbles decreases, correspondingly, the area of mass exchange processes decreases. Thus, when the number of bubbles decreases by 2 times, the area of interaction between gas and metal decreases by 22, that is, by 4 times, when the number of bubbles decreases by 4 times, the area of interaction decreases by 16 times by this value, accordingly, the rate of mass transfer processes decreases. In addition, a decrease in the density of the gas flow leads to a decrease in the lifting force of high-speed metal flows, and therefore, its rate of ascent. This is the main factor in the need for homogenization of the melt in terms of temperature and chemical composition (the driving force of the convective flow is the difference in the specific gravity of the liquid metal filled with gas bubbles and without them, the greater this value, the higher the velocity vector). The removal of non-metallic inclusions occurs, mainly, on the surface of gas bubbles, therefore, the rate of refining depends directly on their number and the quadratic degree on their total area. Thus, the chosen interval between rows is the most optimal

Execution example 1.

The refractory concrete block has the dimensions of the lower base (a) equal to 423 mm, the upper base (c) - 220 mm, and the height (p) - 423 mm. The thickness of the first layer is 120 mm and the second, collector layer is 3 mm. Gas-permeable zones are made of 2 layers of kapron mesh with a cell of 2xX1.5 mm. and the thread diameter is 0.25 mm. Distance between rows ZOmm.

A total of 14 rows. In this way, the total length is 4500 mm. or 6,000 capillaries, their gas-permeable area will be 294.4 mm?, which is significantly greater than the area of slotted and blowable capillary purge plugs and blocks. Yes, IC plugs) with 24 radially located slits have a total blown area of 77.76 mm.

MNAFZB-25 - 33.bmm?, And 2-88 the blowing zone consists of 32 slits 15x0.15, that is, the total area is 72mm".

Moreover, the blowing zones in the proposed block are distributed over an area equal to 136,000 mm, while the zones of traffic jams that are blown out are concentrated on an area of 5,278 mm? (MNA5B-25) up to 1266 mm: (I C).

The shape of the blocks allows you to stack them along a circle with a radius of 808 mm coaxially with the bottom of the container (see Fig. 5), therefore, the proposed block allows you to blow metal through half of the area of the bottom of the container with its diameter of 2000 mm. This purging technology, according to numerous publications in scientific literature and industrial tests, is the most rational from the point of view of hydrodynamic processes, and the area of mass transfer processes is maximal.

Example of specific execution 2.

The block for blowing metal with gas has dimensions of 300x160x150mm. with a working surface of 300x16b0mm. There are gas-permeable areas along the block every 20 mm. etc. 8 sections across the entire length and width of 1.5-2.0 mm. Thus, the total length of gas-permeable areas is 2400 mm. Capillaries formed using a double layer of nylon mesh with a cell of 2.0 x 1.5 mm and a thread diameter of 0.25 mm will form 3200 capillaries with a blown area of 157 mm.

The block is made of refractory concrete with a resistance exceeding that of artificial refractories by 2-4 times.

This will make it possible to make intermediate repairs to the bottom without complete cooling of the entire container by the method of pouring the worn artificial masonry with refractory concrete.

The dimensions of the block are multiples of artificial refractories (80x300x150mm; 160x300x150; 240x300x150;). Exceeding the dimensions of 240x300x150 is not rational because difficulties arise in the manufacture of the blowing zone of the required configuration (see Fig. 4). For example, when stacking blocks 5 together with brickwork 4 of the bottom of the container to form a ring configuration, it is most rational to use blocks no larger than 160x300x150. When using blocks with dimensions of 80x300x150, the production time of masonry work increases significantly due to the increase in the number of seams. In addition, the quality of the lining decreases due to the appearance of a subjective factor - the skill and professionalism of masons, the quality of the masonry mortar, increased wear of the lining due to erosion of the seams (one of the advantages of monolithic linings is the absence of seams, because the wear of linings occurs mainly at the seams). The proposed blocks are more universal because they can be used not only in linings made of artificial refractories, but also monolithic ones. Stacking of blocks is done according to traditional technologies of laying artificial refractories on the collector bulk layer, or the collector layer made together with the block. 1 fneteatyakya, B 2

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Claims (4)

1. A device for blowing metal with gases, containing a working layer of refractory material, linear gas-permeable zones, which is distinguished by the fact that the device is made of monolithic refractory concrete in the form of a block with gas-permeable linear zones no more than 2 mm thick, with a capillary diameter of 0.2- 0.3 mm and the distance between them 1.0-2.0 mm, and the distance between zones 20-40 mm. 2. The device according to claim 1, which differs in that the device has a collector layer with a thickness of 20-30 mm, made of concrete of the same composition as the working layer, but additionally diluted with 50 95 refractory crushed stone with a fraction of 5-15 MM. 3. The device according to claim 1, which differs in that the device is made in the form of a truncated pyramid with an aspect ratio: lower base 1, height 1, upper side 0.52 and a thickness of 120-200 mm. 4. The device according to claim 1, which is characterized by the fact that the device is made in the form of a parallelepiped with an aspect ratio that is a multiple of the sides of a refractory artificial brick.