Slag pot introduction
Slag pot is the place where iron and slag are produced. The modern blast furnace iron extraction field is equipped with mud gun (plugging machine), opening machine, swing flow groove, crane, iron tank, slag tank and other equipment. The mud cannon was pneumatic, then electric. In the 1970s, the hydraulic mud gun was used, which is small in size, large in thrust, long in life and easy to maintain. There are two kinds of opening machine: electric and pneumatic. After the blast furnace molten iron flows into the iron tank, it is sent to the steel mill by train. The blast furnace above 2000 meters uses 150-600 tons of iron water tank (torpedo type mixed iron car), each time 2 to 3 cans of iron. The inclination Angle of swinging flow iron trough is 1°~4°, and the inclination Angle of swinging flow slag trough is 3°~6°. Modern blast furnace slag, take in front of the furnace water slag or set up dry slag pit (see the utilization of high furnace slag). Smoke permeates the drawing yard when iron is drawn. After the 1970s, most of the use of exhaust fan and cloth bag dust, furnace dust after recovery of lead, zinc, can be used as sintering or pellet raw material. Some blast furnaces also set cast iron machine, cast iron machine has roller type and fixed wheel type two, cast iron capacity is generally 200~300 tons/hour.
Folding edit this section using principle
Slag pot is mainly used for bearing converter slag, refining slag and continuous casting of large bales and so on. Under the condition of steel slag in converter smelting process temperature is higher than the temperature of the liquid steel (because the steel slag is located in the high temperature of oxygen blowing reaction area), after the smelting in converter slag splashing process, the composition such as falls or furnace slag, such as operation, can make cover on the surface of the liquid steel, a drop in the temperature of the liquid steel slag, in theory, such a high temperature molten steel slag have to wear the risk of slag pot. But the slag film once formed, combined with cast steel material possesses the advantages of fast heat fast, thermal conductivity, slag pot body surface to convection, will therefore not be slag pot red deformation caused by the temperature too high, the temperature of the tank of liquid steel slag and slag is gradually reduced, so the slag film is hard to melt, it is fully guarantee the safety of slag tank has enough. Of course, if the high temperature molten steel continues to enter the slag tank before the steel slag, its impact kinetic energy and high temperature are likely to cause the slag tank penetration accident; On the other hand, if the slag enters the slag tank first, then the risk of wearing the tank is much smaller, which is also the technical principle of casting steel slag pot can safely carry high temperature steel slag.
Fold edit this section life influencing factors
1. Influence of abnormal slag of converter:
Although it is safe to carry steel slag in the cast steel slag tank, there is still a risk for abnormal slag of converter. The abnormal slag of converter is mainly the slag of washing furnace before dismantling and the slag of high temperature and high oxide produced by smelting special steel. Furnace washing is to dissolve the splashing slag layer and the adherent slag and charging material on the converter lining through the high temperature slag, so as to facilitate the subsequent furnace dismantling work. The temperature of steel slag produced is higher than that of conventional slag, the content of iron oxide in slag is higher, and the fluidity is good. In the slag tank after the iron oxide slag and slag tank body chemical reaction, coupled with the slag body temperature load impact, it is likely to cause tank accident.
2. Influence of continuous casting of large bale casting:
Continuous casting bag besides part of steel slag, still contain liquid steel, the temperature is higher than or close to the melting point of cast steel, if the slag pot to do special processing, when casting allowance is bigger, direct contact with the molten steel slag pot body possible corrosion slag pot body cause wear tank cast steel materials, the cooled or partial corrosion adhesion sex cohere with the slag pot, It is easy to damage the slag tank when it is turned over.
3, external impact on slag pot damage:
When the slag pot and the steel slag loaded in it have bonded, leading to the normal can not turn over the tank, need to use the gun car to continuously hit to help pour out the slag in the slag tank, the mechanical force in the process of beating in the form of wave transfer in the slag tank, and in the local formation of superposition, resulting in the damage of the slag tank.
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In production practice, there are mainly the following problems when using slag tank in ferroalloy smelting:
(1) Due to the design of the overflow mouth of the slag tank, the center of gravity of the slag tank is offset, which causes tilt in the lifting process, and the slag liquid is easy to overflow, which has great hidden trouble.
(2) The overall structure of the slag pot is unreasonable, and it is easy to crack after being subjected to thermal stress, which will lead to the breaking of the bag.
(3) The design uses one lined molten iron bag and three slag bags. Sometimes too much molten iron will overflow into the slag tank, resulting in a sharp rise in the temperature at the bottom of the slag tank, which will cause damage to the slag tank.
Fold edit this section to improve measures
1. Thicken the slag pot wall inside the back of the slag pot, so that the center of gravity can be balanced after the slag tank is lifted.
2. The improvement part is to cancel the strengthening edge of the upper part of the slag tank, the bottom and the middle and upper parts of the slag tank are thin and uniform, the expansion seam is reserved at the strengthening edge of the bottom, and the strong reinforcement is added at the bottom
3, change the structure of the iron car, from the original combination of three slag POTS with a lined molten iron bag to two lined molten iron bags and two slag POTS, can effectively prevent iron water flow into the slag tank, causing local high temperature damage to the slag pot.
Folding edit this section of slag can spray technique
1. The implementation of slag can spraying technology can effectively eliminate the smoke pollution of steel slag can be turned over:
After the converter steel, most of the residual part of molten steel in the furnace, especially in the late furnace service, the lining erosion is serious, convex and concave uneven. More steel remains. When the slag is poured into the converter, the molten steel is followed by the slag into the slag tank. The temperature of the molten steel is mostly above 1500℃. The part of a slag tank that is scoured by molten steel. The slag shell is corroded and the cast iron slag tank is in direct contact with molten steel. Melted by molten steel, after cooling molten steel and cast iron slag tank welding together, resulting in sticky tank. The high temperature resistant coating layer formed on the inner wall of the slag tank can isolate the residual molten steel and the corrosion of the slag tank, so as to avoid or reduce the steel slag sticking to the tank, so as to cancel the slag mat measures, and effectively eliminate the smoke pollution caused by the slag mat. When the spraying slag tank is turned over, it does not produce black smoke, and the white smoke is very little, and disappears quickly. The amount of smoke and dust is more than 90% less than that when the slag is deposited, so that the slag field can maintain a better environment.
2, the implementation of slag tank spraying technology can improve the slag pot removal rate, conducive to slag tank turnover:
A strong heat-resistant coating layer is formed on the inner wall of the slag tank to avoid the contact between the slag and the slag tank and the steel strip water, and the spray material has good slag erosion resistance, so as to significantly reduce the probability of the steel slag sticking to the tank. The surface of the dumped slag is smooth, which proves that the technology can prevent the steel slag from sticking to the tank. The improvement of the one-time removal rate of slag tank accelerates the turnover of slag tank and creates favorable conditions for high production of steel making.
3, the implementation of slag pot spraying technology can reduce the loss of slag pot:
On the one hand, the probability of steel slag sticking to the tank is reduced, and the heavy hammer strike after sticking to the tank is reduced, which is beneficial to improve the service life of the slag tank; On the other hand, it is related to the thermal conductivity of spray coating layer. The thermal conductivity of spray coating is poor, and it has the function of heat insulation. It can reduce the temperature of the slag tank after the slag is canned, reduce the temperature gradient between the slag tank and the surrounding environment, reduce the thermal stress caused by rapid cooling and rapid heating, and prolong the life of the slag tank; Because of the poor thermal conductivity of spray coating, it has the function of heat insulation, which can reduce the heating temperature of the inner wall of the slag tank and avoid the corrosion of the inner wall of the slag tank at high temperature.