The size of a reverberatory furnace is generally expressed by the area of the furnace bed (the area at the surface of the slag line), and there are also some that express its size according to the amount of metal added (t). Reverberatory furnaces are designed into various sizes as needed, with a small area of only a few square meters and a large area of 360m².
The reverberatory furnace is heated by end burners, and the fuel is mainly pulverized coal or heavy oil. The temperature in the furnace can reach about 1500℃. Due to the strong penetration of the melt and the severe erosion of the slag, the furnace bottom, furnace wall, furnace top and parts in direct contact with the flame are generally built with alkaline refractory materials such as sintered magnesia bricks, magnesia-chrome bricks and magnesia-alumina bricks. The smelting reverberatory furnace generally adopts a hanging furnace roof, while the large smelting reverberatory furnace roof adopts a hanging pressure arch structure. In order to prevent the furnace bottom masonry from floating up, the top layer of furnace bottom bricks is built into an anti-arch. On the anti-arch, a layer of magnesia iron ramming material is used, which is rammed with metallurgical magnesia sand and iron oxide powder and brine. After baking and high-temperature sintering at about 1600℃, an integral magnesia sintering furnace bottom is formed.
1. Conditions that should be met before the construction of the reverberatory furnace:
The elevation and flatness of the surface of the refractory castable foundation meet the requirements of the design and specifications;
The furnace structure is installed and its size meets the design requirements;
The water cooling device is installed and the pressure test is qualified.
2. Masonry of the furnace bottom
Before construction, use the theodolite to measure the center line of the furnace and re-measure the foundation elevation; at the same time, mark the elevation of the first layer of bricks on the furnace column or furnace shell, and mark one point every 5m or so. Then, draw the layer height line in the vertical direction in sequence as the benchmark for masonry of the furnace bottom and furnace wall.
Before the construction of the furnace bottom of the smelting reverberatory furnace without furnace shell, the furnace bottom wall should be wet-laid with clay bricks. When laying, pull the line according to the elevation on the column. After the furnace bottom wall is built, the brick layer line of the furnace bottom is drawn on its inner surface to control the layer height. All the bricks of the furnace bottom are dry-laid.
First, lay the asbestos board on the basis of the refractory castable, and the joints should be neat and tight. Then, lay the quartz sand. The main function of the laying material is to level the first layer of bricks (clay insulation refractory bricks) of the furnace bottom, so the laying material should be carried out at the same time as the masonry of the first layer of bricks. The thickness of the laying layer is about 40mm. In order to minimize the moisture contained in the masonry of the furnace bottom, quartz sand with a particle size of less than 2mm should be used.
The furnace bottom bricks are reversed (113mm thick). The upper surface of the first layer of bricks must be laid flat. When laying, draw the lines vertically and horizontally, starting from the middle to both ends, and the expansion joints are concentrated in sections.
The ramming layer is set under the anti-arch to form the arc surface required for the masonry of the anti-arch bricks. Therefore, the curvature should be accurate. After ramming, check with an arc template. The gap between the ramming layer surface and the template shall not be greater than 3mm. The ramming is generally carried out from the middle to both ends, and the concave formwork is supported at 2m sections. When supporting the formwork, it should be accurately positioned according to the elevation line drawn on the furnace bottom wall. The joints of each section are naturally rammed. Since the solitary ramming layer is thin and the thickness is inconsistent, it only needs to be compacted with a wooden slap. The surface is scraped along the curved surface of the concave formwork with a wooden scraper, and the material is scraped flat while being rammed.
After the ramming layer is completed, it should be dried or dried naturally, and then covered with linoleum to prevent dirt and damage.
The anti-arch bricks start from the longitudinal center line of one end of the furnace and are laid on both sides at the same time. During construction, one ring is laid first, and then this ring is used as the standard for laying in sequence. The brick ring of the first ring of bricks must be flat and vertical, and close to the furnace end wall. The longitudinal and transverse expansion joints should be dispersed according to the design. When there is a sintering layer on the anti-arch of the copper smelting reverberatory furnace, a concentrated expansion joint can be left at the junction of the two sides of the anti-arch with the furnace wall, and the joint is filled with quartz sand about 2/3 of the depth. When there is no sintering layer on the counter-arch, the counter-arch should be staggered and wet-laid, and the arch feet on both sides of the counter-arch connected to the furnace wall must be carefully built into the wall. After the counter-arch is built, it should be covered with tarpaulin.
3. Masonry of furnace wall
When building a vertical wall, it should start from the four corners and the middle of the wall at the same time, and pull the line layer by layer. The middle brick layer should meet the corresponding layer height line marked on the column to ensure that the wall is horizontal and vertical.
The size and position of the expansion joint should be accurate, avoid the stress-bearing parts, the furnace frame and the holes in the masonry, stagger inside and outside, cross up and down, and keep it uniform and straight. The seam should be clean, and mud and other debris should not fall into it, and thick cardboard should be filled as required.
The masonry of the slag return port, matte port, siphon copper release port and other parts should be pre-built. For parts with holes in the masonry, masonry should be started from the hole position to both sides. The size of the hole should be accurate. The top bricks of the stepped masonry at the material slope shall not be laid in a straight line.
4. Masonry of the furnace roof
The furnace roof has a large span, and the arch support must be firm. Before supporting the arch, a level should be used to measure the horizontal elevation slightly lower than the arch foot, and the design elevation line of the arch should be returned based on this. When supporting the arch, it should be positioned strictly according to this line. The spacing between the arch frame pieces is 450~500mm, and the load-bearing beam must be supported on the node of the arch frame piece. The longitudinal distance between the pillars shall not be greater than 800mm, the vertical and horizontal diagonal braces between the pillars shall be nailed firmly, and the lower part of the pillars shall be wedged with wooden wedges, and a 30mm wide gap can be left between the arch and the furnace wall. After the full-hall arch is supported, supports should be added at both ends to fix it.
First, two corresponding positioning arch foot bricks are set at both ends of the furnace roof at the same time, and their angles and positions meet the design requirements, and then a through line is drawn along the upper and lower edges of the arch foot surface, and the arch foot bricks on both sides are masonry based on this.
The arch foot bricks and arch foot beams of the hanging vault must be tightly bricked. The expansion joints of the arch foot brick masonry should be concentrated, and their positions are generally at the joints of the arch foot beams.
The masonry of the furnace roof in the charging port area is staggered and wet-laid. The charging port is located between the two columns, and its sealing brick layer should be laid from the sealing brick. In addition, one side of the sealing brick must be embedded in the upper and lower brick layers, and no straight seams should be left. The expansion joints of the masonry in the charging port area can be set in accordance with the expansion joints of the arch foot brick masonry.
The brick ring of the hanging vault. The first layer of bricks of the hanging vault and the last layer of bricks of the charging port should be wet-laid without pins. Note that the side should maintain a 1~1.5mm brick joint, which should not be too close, and concentrated expansion joints should be set in sections according to the design, and the joints should be filled with aluminum silicate fiberboard.
When laying the hanging vault, it is generally started from the middle and laid symmetrically from the arch feet on both sides to the center. First try to build a ring, strictly adjust the brick ring to be straight according to the regulations, and use this as a reference to build other brick rings in sequence. Pins and 0.5mm thick steel gaskets are inserted between bricks, and 1mm thick cardboard is also inserted between every two bricks. The hanging arch should be locked in rings, and the locking degree of each ring should be consistent. After the bricks are locked, the hanging long pin should be inserted immediately.
When the furnace roof is built, the arch tire can only be removed after the hanging steel parts are installed and the tie rods between the columns are tightened.
5. Masonry of inclined flue
An expansion joint should be left at the junction of the inclined flue wall and the main wall of the furnace body, and the joint should be filled with aluminum silicate fiberboard.
The expansion joints of the front and rear arch sections of the water-cooled gate should be dispersed. The masonry at the junction with the water-cooled frame must be close.
The hanging brick group must be firmly bonded and the surface must be flat. When constructing the hanging arch, the elevation line should be pulled and masonry should be built layer by layer. The closing bricks at the joints of the vertical hanging vault bricks and the hanging vault bricks must be suspended in the same supporting way as the hanging vault bricks. When the vertical hanging vault is completed, magnesium mud should be poured on it.