Converter steelmaking is widely adopted by domestic and foreign steel smelting industry for its high productivity, variety, good quality, high thermal efficiency, good adaptability of raw materials, low consumption, low cost, low infrastructure investment, fast construction speed, etc. It has become one of the main methods of modern steelmaking. The refractory materials for furnace lining are mainly magnesium carbon bricks, sintered magnesium bricks, castables, etc. The construction sequence and methods are as follows.
The masonry is carried out in five parts, namely, furnace bottom, melt pool, furnace body, steel outlet and furnace cap, and the masonry is done in an upward manner. Since the furnace shell steel plate in order for the permanent layer, the working layer, the permanent lining using fired magnesium bricks, the working lining using magnesium carbon bricks. Magnesium bricks and magnesium carbon bricks are dry-laid, and the key parts of the permanent layer can be wet-laid.
Construction method
1.Masonry of furnace bottom
The permanent layer is constructed of magnesium bricks, with two layers of standard bricks laid flat. Masonry using “a word” masonry way, the requirements of the bottom of the furnace close to the steel shell, staggered brick seams. The center line of the second permanent layer of brick should be perpendicular to the center line of the first layer. Masonry to the outside, with pounding material to fill the gap between the brick and the steel plate tightly, with a hand hammer or wooden board for pounding. Each layer of brick masonry to the bottom of the blowing gas supply element position reserved openings, to the bottom of the furnace steel shell on the center of the opening as the center of the base point, to ensure that the breathable bricks are installed with a margin of adjustment to reduce the amount of cut bricks. After each layer of masonry, with magnesium fire clay dry powder evenly spread a layer, fill the brick joints with a broom after sweeping. After building the magnesium brick at the bottom of the furnace, build the working layer at the bottom of the furnace, and install the center brick at the center of the furnace bottom. Setting the starting line: take the center of the center brick as the starting point, the whole furnace bottom takes the ring masonry, total 12 rings (excluding the center brick), masonry to the gas supply brick pre-drilled holes when installing the gas supply brick.
2.Installation of breathable tiles
This service of 12 ladle purging plug of the service of the refractory part of its external dimensions are the same, installation, should try to install the breathable bricks in the center of the furnace shell aperture position, if the position is not suitable for the situation, even through the position of the position adjustment can not be installed in place, can be used in the following three ways to deal with:
① Processing of bricks around the breathable bricks, requiring the processing of bricks shall not be used around the breathable bricks, and the size of the processed bricks need to meet the masonry requirements.
② Expand the openings on the furnace shell to ensure that the bottom blowing breathable bricks are placed in the ring, as little as possible to process the bottom of the furnace bricks.
③ Use the breathable brick wood model for trial swing before installing ladle breathable brick, after the installation of the gap position, be sure to use refractory materials to fill tightly. The installation process must be careful to ensure that the breathable brick tail pipe is not damaged, requiring the breathable brick bottom blowing pipe and the upper surface before masonry with tape paper for protection.
3.Masonry of dissolving pools
The furnace bottom is designed as a spherical bottom, with a circular transition between the molten pool and the furnace bottom. The gap between the working lining and the permanent lining is filled with tamping material and smoothed with a wind hammer. Refractory brick masonry should be strictly operated to ensure that as far as possible after 12 layers of masonry level, to lay a good foundation for the body of the furnace masonry. Ensure that each layer of brick masonry ring level, and with the bottom of the furnace brick against the tight and solid. The total number of brick layers of the melting pool is 12, according to the design drawings and brick type. Each layer needs to be cut when closing the door. Requirements for the cut brick type to ensure that the outside is large and the inside is small, and the size of the cut brick is greater than 1/2 the thickness of the brick. The bricks of the upper and lower layers are staggered by more than 60°.
4.Masonry of the furnace body
The masonry body of the furnace is laid first with permanent layer, adopting side masonry, the thickness of the permanent lining is 115mm, and the total number of layers is 18. Furnace body working lining a total of 25 layers, staggered between the layers, each section of masonry according to clockwise, counterclockwise alternating masonry, hinged door bricks measure the size of the cutting process, the processing requirements and the melting pool of brick masonry requirements are the same. The design of the charging side, the steel side and the trunnion are made of different materials, therefore, the masonry in this area should be strictly according to the identification of the brick masonry respectively, to avoid the wrong masonry of bricks made of different materials.
5.Masonry of steel outlet
Sleeve bricks and seat bricks are assembled and installed, the assembly should ensure that the sleeve bricks and seat bricks are concentric, and the gap is pounded solid with pounding material. In the placement of the whole ladle nozzle well block, and then masonry around the other cap brick. Seat brick around the use of wet masonry, the outlet around the 1m range without leaving expansion joints. After the cap bricks are laid to 2-3 layers above the outlet, the periphery of the outlet will be filled with pounding materials and pressed firmly.
6.Masonry of furnace cap and opening
The permanent lining of the furnace cap and the steel plate are tightly plugged with magnesium filler, and there is no permanent lining after 53-55 layers of working lining. Work lining masonry is completed after the furnace water cooling plate left under the 50-80mm gap, this gap is filled with dry thick magnesium castable material, and with wooden wedges tightly plugged to prevent shaking the furnace loose, is strictly prohibited with magnesium-carbon bricks top dead, to prevent the expansion of water-cooled pieces of deformation.
7.Expansion joints
In order to compensate for the expansion of refractory materials in the process of heating up the kiln, the expansion paper is inserted into the brick body, different parts of the furnace bricklaying work, the insertion of different parts of the placement and distribution of the expansion material used is 1mm thick ceramic fiber paper. Furnace body vertical expansion joints for every 3 layers (starting from 13 layers) increase 1 layer of 1mm ceramic fiber paper, horizontal for each ring every 6 blocks using 1 layer of 1mm ceramic fiber paper. The vertical expansion joint of the furnace cap is to add 1 layer of 1mm ceramic fiber paper for every 3 layers (until the end after 46 layers), and the horizontal expansion joint is to use 1 layer of 1mm ceramic fiber paper for every 6 blocks of every ring (until the end after 44 layers).
8.Masonry finishing work
After the masonry work is completed, the masonry platform will be lifted out according to the sequence, taking care not to touch the furnace lining bricks. After the platform is lifted out, clean up the debris in the furnace and do not leave residual bricks in the furnace. After masonry, the bottom of the furnace and the corner area of the melting pool are protected by pounding a furnace slope with pounding material.