The cause and treatment of the main trench fractur

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The reason and treatment of the fracture of the main ditch of blast furnace

the iron storage main ditch is a container for holding iron. It must bear not only the thermal stress, but also the pressure of molten iron. After the steel shell of the main ditch cracks, the pressure of molten iron is borne by the lining. Once the permanent layer masonry is damaged and the molten iron leaks, it will cause a major production accident. The main reasons for the fracture of the main ditch are as follows:

1. Mechanical punching of high-temperature slag iron. The reason for this description is that the electronic scale weighs the steady-state signal brush and chemical erosion

the slag iron with high temperature and high pressure flows out of the iron mouth quickly, which will scour the main ditch violently. In addition, the alkaline substances such as MgO and Cao in the furnace slag and the SiO2 sculpture in the iron ditch material are based on the extraction of painting and the chemical reaction of Al2O3 to produce low melting point compounds, It slags and dissolves the main ditch material, destroys the overall strength of the main ditch, makes the working lining of the main ditch thinner and thinner, and breaks under the action of bending stress

2. Design problem

the brick lining of the main ditch is relatively thin, especially the upper part of the main ditch is not bricked. When the working lining of the upper part of the main ditch is eroded to a certain extent, it will crack first because there is no brick layer protection

3. Installation problems

due to the overall size of the main trench, it is generally installed by two-stage manufacturing on-site welding. When the material of the weld at the junction of the main trench fails to reach the strength of the base metal, it becomes a weak point under stress and generates tension fracture

the treatment measures are:

1. Reinforce the old main ditch

lay bricks at the crack on the upper part of the main ditch; The side fracture at the air duct of the side wall of the main ditch is connected with a stiffener plate; Reinforce the bottom of the main ditch; Wrap a box at the joint of the main ditch air duct and the main ditch bricklaying to ensure the thermal load stress release of the experimental shell for measuring the impact load resistance of metal materials by the main ditch steel, and do not affect the cracking of the welded junction

2. The weld treatment of new main ditch

shall be carried out in sections. The steel shell of the main trench is designed according to the drawing of the steel shell of the main trench. The welds at the sections are staggered with each other, and the on-site welding is carried out according to the equipment requirements, so that the strength of the on-site weld is not lower than that of the base metal. In addition, at the inner side of the main ditch, the on-site welds of the main ditch shall be strengthened by sticking plates

3. Daily protection

strengthen the production operation, do a good job in the maintenance of the iron mouth, avoid the big spray of the iron mouth, and reduce the mechanical scouring of the main ditch, especially the side wall; Select good quality castables for main ditch; The main trench working lining shall be controlled not to be overused, so that the main trench working lining before trench repair can maintain a certain thickness, reduce the thermal load of the main trench steel shell, and protect the main trench steel shell

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