Because dolomite clinker is crushed when it meets water, anhydrous binder is needed to make bricks. Generally tar, asphalt, anthracene oil, etc. organic
This combination prevents hydration, and when it is cracked by heat in the brick, the remaining carbon will greatly improve the performance of the brick. In oxygen
All kinds of attempts to apply asphalt-free brick in gas-alkali furnace are disappointing. It can be said that residual carbon and
It is also an important part of dolomite brick.
When making bricks, asphalt is added (or impregnated), and the asphalt is thermally cracked and separated in an alkaline oxygen converter, so that a small amount of carbon is in the pores of the bricks.
Formed "carbon residue", which exists in many forms, but in most cases, it is compressed at one end of the pore. from
At present, all known conditions show that any form of carbon does not play a role in the combination of refractory particles, but only plays a role.
It is just a filler that exists in the pores of the brick. The size, shape and continuity of residual carbon particles are mainly related to the closed pore form.
Size has little to do with asphalt properties.
However, the good effect of a small amount of carbon is certain. Basic oxygen top-blown converter contains carbon, but does not.
Compared with carbon bricks (Figure 9), it can be clearly seen that a small amount of carbon reduces the infiltration and infiltration of iron oxide into bricks.
Transfer.
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The second chapter is the optimization design of dolomite refractory production formula.
The obvious difference in air permeability between carbon-containing bricks and carbon-free bricks is also reflected in the use. The erosion rate of carbon-containing bricks is uniform and slow.
Slow, there is an increasing trend in the later period. The non-carbon brick near the working face forms metamorphic layer, and presents considerable thickness uncertainty.
Structural spalling. Due to the absorption of iron oxide and silicon dioxide, the composition of the original brick is changed,
Thermal expansion and density vary with depth. Compared with this, the properties of carbon-containing bricks have little change along the depth, showing strong resistance.
Tissue shedding.
The ability of carbon to inhibit the deep penetration of slag is the result of several factors. Generally speaking, this is related to the residue in the pores.
Carbon will reduce the wettability of slag. If there is no substance with poor wettability such as carbon in the pores, the slag will directly invade.
The depth of the pore until it solidifies. If there are disordered graphite particles in the pores, slag intrusion is limited to hot surfaces.
Nearby. In addition, the pressure generated by carbon oxidation is also a factor to prevent slag infiltration.
The important role of carbon can also be explained from the melting relationship. For dolomite brick, its phase diagram is as shown in the figure.
The reducing atmosphere caused by carbon can make dolomite bricks (such as those containing adsorbed iron oxide) contain no liquid.
Stage. When there is no carbon in the brick, that is, in the air atmosphere, only the iron oxide absorbed by the brick begins to melt.
A lot of research has been done on the problem of carbon content. When the carbon content is. The penetration of slag increases rapidly. Therefore,
In order to reduce the penetration of slag, the residual carbon content should not be less than.
Figure Periclase with and without asphalt
Comparison of chemical constituents in Shi Zhuan.
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The fourth part is the optimization design of the production formula of alkaline and spinel refractories.
Figure —— Isothermal Cross Section of Iron Oxide System
-reducing atmosphere (01; 2- In the air; 3- magnesium-rich body; 4- magnesium ferrite; 5- liquid phase
The carbon in brick mainly comes from organic binder or impregnating material (tar or asphalt). Its carbon content is related to the softening point of asphalt.
And carbonization temperature (figure 6. It is best to choose asphalt with high softening point and pay attention to the appropriate carbonization temperature. in addition
Increasing the carbon content can increase the amount of asphalt, and add an appropriate amount of carbon, such as carbon black.
It is not enough to increase the carbon content, because the structure of carbon has a great influence on the corrosion resistance of lining bricks. Oil-immersed brick
Generally speaking, the pore structure and porosity of brick are mainly considered. Of course, bricks with fine pore structure and uniform carbon distribution have slag resistance.
Permeation is more favorable than macroporous structure and coarse carbon.
Influence of softening point and carbonization temperature of asphalt on carbon content.
Four, the production process of tar dolomite brick
Tar dolomite brick is made of sintered dolomite as the main raw material or adding appropriate amount of magnesium oxide and tar pitch or wax.
Made into adhesive. Brick-making process is shown in the figure.
The quality of raw materials, chemical composition and sintering degree of sintered dolomite are related to the performance and properties of products.
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Chapter II Optimization Design of Dolomitic Refractory Production Formula 79
Service life. In order to meet the requirements of oxygen top-blown converter lining, dolomite clinker should be a material with high purity and good sinterability.
And impurities, and the bulk density should be greater than .01.0234.
56, preferably greater than 03456.
The components of tar dolomite products composed of 0 particles are relatively simple, and a single component is generally used, sometimes in order to improve its resistance.
Hydration performance, fine powder can be partially or completely replaced by magnesium oxide fine powder.
The compactness and hydration resistance of the product should be considered when the particles are mixed, which also varies with different molding methods. Cooked coarse dolomite
The material has small specific surface area, small contact area with air and strong hydration resistance. Experimental research and production practice have proved that coarse particle mixing
It is beneficial to improve the density, hydration resistance and erosion resistance of tar dolomite brick. Currently, more critical particle sizes are used.
It is 7.366 or 27366.
Although fine powder has the disadvantage of easy hydration, it can fill the gap between large and medium particles, which is beneficial to improve the bulk density and the use of bricks
When sintering, and ensure that the brick surface boundary is neat. At the same time, fine powder can make the adhesive film around large particles thinner, so tar can be used.
Burn it in the process to avoid leaving too many pores in the future.
Fig. 8.873 process flow chart of machine-made tar dolomite brick
In the process of mechanical compression molding, particles are subjected to strong external pressure. If the particle sizes are very different, the stress on large particles cannot be very fast.
And the uniform transmission will cause the crushing of large particles.
In order to prevent the particles from breaking, reduce the stress on the particles, and quickly and evenly transfer the pressure on the particles to the base of the machine, the machine is pressed.
The molding material should contain enough small and medium particles.
During vibration molding, particles are not subjected to one-way pressure, but are subjected to forces in different directions between particles, resulting in effects.
It is not the extrusion between particles, but the looseness, so there will not be too many restrictions on the composition of particles in the process of fixing the particle arrangement.
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The fourth part is the optimization design of the production formula of alkaline and spinel refractories.
System. It is not necessary to follow the structure of mechanical brick pressing, but should be similar to the structure of concrete in buildings. According to the brick particle knot
According to the characteristics of this structure, it can be seen that high dispersion and uniformity are formed by using particles much larger than the mechanically pressed brick material and eliminating intermediate particles.
The particle structure is reasonable and feasible.
Blank preparation
Dry the sand. So as to avoid the heated asphalt and dolomite clinker from being sucked by the cold dolomite clinker during the mixing process.
The fluidity of binder is reduced by heating, and dolomite sand should be heated to a high enough temperature. Drying sand is heated dolomite sand.
If the temperature of dry sand is too low, the viscosity of tar will increase and the mixing will be uneven. If the temperature is too high, some substances in the adhesive will be evaporated.
Volatilization changes the composition and pollutes the operating environment. In general, the temperature of clinker sand should be controlled within 100℃, and it can only be baked at medium and large temperatures.
Granular and fine powder can be baked or not. Shougang's dry sand temperature is (machine-made brick, (vibration molding brick.
Materials; Tang Gangwei; Shanghai iron and steel co., ltd. No.1 factory has 0 coarse particles and 0 fine powder.
Sand drying equipment mainly adopts reverberatory furnace and vertical heating furnace.
Adhesive and its preparation. Dolomite sand is poor material, and suitable binder must be added during modeling. Coal is usually used.
Tar asphalt, petroleum asphalt, coal tar, anthracene oil, etc. The properties of various adhesives are shown in the table. Function of magnesia-carbon brick magnesia-carbon brick magnesia-carbon brick
Magnesium-carbon refractories were successfully developed in the United States in the mid-1960s. In 1970s, the Japanese steelmaking industry began to use magnesia-carbon bricks in water-cooled electric arc furnace steelmaking. At present, magnesia-carbon brick has been widely used in steelmaking all over the world and has become the traditional use of graphite. In the early 1980 s, magnesia-carbon bricks began to be used as lining of oxygen top-blown converter. At present, the lining materials used in oxygen top-blown steelmaking in Britain are mostly magnesia-carbon bricks, and the lining life is 1000-1500 times, while that in Japan is 2000 -2500 times. alumina carbon brick
Aluminum-carbon refractories are mainly used in the protective cover of continuous casting and flat slab self-positioning pipelines, underwater nozzles and oil well blasting barrels. In Japan, steel produced by continuous casting accounts for more than 90% of the total output, while in Britain it accounts for 60%. The function of clay brick Clay brick, the function of clay brick, what are the functions of clay brick? Product features of Peninsula Brick Machine: 1. The fuselage of the whole machine adopts standard high-strength steel and advanced carbon dioxide gas shielded welding to ensure the durability of the fuselage. 2. The senior technician makes it carefully to ensure the accuracy of raw material blanking, parts processing and assembly of the whole machine, so as to ensure the fast, stable and reliable operation of the whole machine. 3. Guide post: After rough machining, finish machining, normalizing and tempering, cylindrical grinding, chromium plating and other technological treatments, it ensures high strength, high torsion resistance and high wear resistance. 4. Mold: made of precision cast manganese steel, with carburized surface to ensure long service life. One-step molding and single-chip assembly greatly reduce the damage probability and replacement cost. 5. Hydraulic and control system: the main components are made of well-known brands to prevent pressure release and leakage. Ensure the long-term stable operation of the whole machine. 6. Molding system: The internationally advanced high-frequency directional vibration technology is adopted to ensure that concrete products of various materials and specifications can achieve the best compaction effect and ensure the compactness of the products. 7. Distribution system: a unique fork-shaped 360-degree forced distribution system can feed quickly and evenly, effectively shortening the distribution time and improving production efficiency.