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Structural Composition Of Smelting Copper Reverberatory Furnace And Refractory Brick Configuration
Jan 22, 2019

The reverberatory furnace is a traditional thermal equipment for copper concentrate smelting. The reverberatory furnace is a horizontal rectangular furnace, and the structure of the copper reversing furnace is shown in Fig. 1. The reverberatory furnace body is composed of a furnace base, a furnace bottom, a furnace wall, a furnace top and a reinforcing bracket, and further includes a converter slag injection port, a matte copper discharge port, a slag discharge port, and a flue gas passage. The refractory bricks used in the lining are also different depending on the location.

 

(1) Furnace base


The reverberatory furnace is a cumbersome device with a total mass of 1500~3000t, and the furnace charge and melt weight vary with the furnace capacity. The load on the ground is very large, and there must be a good foundation to spread the load evenly to the ground. Otherwise, the furnace may partially sink and crack the brickwork.


The furnace base is generally constructed of coarse stone, block stone concrete or brick concrete. It is the most solid with slag or furnace and concrete. The depth of the furnace base is 2~3m.


The surface of the furnace base is either flush with the ground or above the ground level. If it is flush with the ground, in order to release and transport the copper and slag, there must be an underground road. The choice of the elevation of the base surface of the furnace depends on the method of releasing the melt. For example, the heat transfer slag method is used to increase the elevation of the base surface of the furnace; if the water slag method is used, the elevation can be reduced accordingly.


(2) Bottom


The furnace bottom is under high temperature for a long time, and it is under great pressure and is constantly being washed and chemically attacked by the melt. Therefore, appropriate refractory materials should be selected to build the bottom of the furnace to extend the life of the reverberatory furnace and increase productivity.


The bottom of the furnace is usually sintered with quartz, that is, with ground quartz stone or natural river sand, the particle size is not more than 2 mm, and the SiO2 content is not less than 92% to 96%.


The thickness of the hearth is generally 0.6~1.2m. Firstly, the refractory mud with a thickness of 50~100mm is laid on the furnace base and separated from the furnace base so as to be free to expand when heated. Then, the quartz sand is mixed into the refractory mud which accounts for 5%~8% of its weight, and 5%~7% water is added to wet the mixture. The mixture is smashed on the refractory mud layer by 100~120mm, and then laid again. Shop 5~7 layers. After that, it is heated and sintered, and the temperature rises from low to high according to the heating curve, and rises evenly. When it reaches 1773~1873K, the bottom of the furnace is fired into a whole, which is called the sintering bottom.


The bottom of the furnace can also be built with reversed arches of silica bricks, and can also be sintered by crushing converter slag and waste slag.


When smelting low-grade bronze, the bottom of the silicon furnace is easily eroded due to the large amount of Fe3O4, so the bottom of the magnesia sintered furnace is used. The bottom of the magnesium iron sintering furnace is mixed with a magnesia containing more than 80% of MgO, an iron oxide powder, that is, Fe3O4, Fe203, etc., mixed with brine, layered and compacted, and then heated and sintered. The bottom of the furnace is not only not eroded by Fe3O4 in the melt, but a protective layer of Fe3O4 is formed on the bottom surface of the furnace to extend the life of the furnace bottom.


(3) furnace wall


The furnace wall is directly built on the furnace base, and is usually made of silicon brick. Since the silica brick is susceptible to slag erosion, the inside of the furnace wall below the slag line is lined with magnesia brick, chrome-magnesia brick or magnesium-aluminum brick, and clay brick or silica brick. The furnace wall above the slag line is made of silicon brick, magnesia brick, chrome-magnesium brick or magnesium-aluminum brick. Generally, the slag line is formed into a straight wall, and the slag line is formed into a stepped material slope to enhance the corrosion resistance of the furnace wall to the melt. The thickness of the wall portion of the furnace is generally 500 to 1000 mm, and the thickness of the lower portion is 750 to 1500 mm. When the furnace wall inside the furnace is built, an expansion joint with a width of 25 to 30 mm is left every 300 mm to allow the brick masonry to expand freely when heated. The front wall of the reverberatory furnace is provided with a rectangular channel with a burner installed, and a copper-copper discharge channel is arranged in the middle of the side wall of the furnace tail. The slag discharge channel is arranged at the end wall of the furnace or the side wall of the furnace tail. The converter slag is placed at the end of the furnace. Wall or side wall.


(4) Top of the furnace


The top of the reverberatory furnace has two types: an arched top and a suspended top.


The arched roof is generally composed of several arch sections of 3~7m length. The arch section near the burner head is short and thick because it is in the high temperature zone; the tail section of the furnace is longer than the head arch section, and there are 50 between each arch section. ~70mm expansion joint. The arch height is usually 1/9 to 1/10 of the width of the furnace, and the radius of curvature of the arch is usually 1.2 to 1.3 times the width of the furnace. The arched roof is built on the arched brick in the channel steel beam of the furnace side wall, and the channel steel is fixed on the vertically fastened column next to the furnace. Therefore, the weight of the roof does not fall on the side wall.


The arched roof is generally made of silicon brick. The weight of the silicon brick roof is lighter and the cost is lower than that of the magnesia brick. However, silica bricks are susceptible to erosion by alkaline dust, thus limiting the width of the reverberatory furnace.


The hanging top is embedded with 2~3mm thick iron plates between 4~8 bricks to form a brick group. When the top of the furnace is heated, the iron plate melts, so that the bricks stick to each other. The brick group is made of magnesia brick, chrome-magnesia brick or magnesia-aluminum brick with heavy weight and high refractoriness. All the brick groups are independently hung on the horizontal iron frame, and the width of the furnace is wider than the arched top.


The roof of the thrust type ceiling structure is actually a combination of a dome top and a suspended roof. The arch height is 1140 mm and the radius of curvature of the dome is 7790 mm. Since the rails of the hanging brick group are fixed by the clamps and the pressure beams, the top of the furnace is restrained during thermal expansion and contraction, so that the deformation of each brick group is not large, thereby reducing the undulation of the furnace roof and prolonging the life.


1-arch beam; 2-magnesium-aluminum brick; 3-pressure beam; 4-hanger; 5-cross tie rod; 6-beam; 7-beam


(5) Reinforced bracket


The reinforcing bracket of the reverberatory furnace consists of a strut standing around the furnace and a tie rod that runs over the top of the furnace and below the reverberatory furnace. The I-beam or channel steel pillars are combined in pairs, the spacing of the pillars is 1~1.2mm, and the round steel of 38~50mm is used as the tie rod, and the two ends are threaded and fixed on the pair of pillars. When the reverberatory furnace is heated, the nut on the rod is rotated in time to adjust the tension to avoid deformation of the pillar and the brickwork. A gap of 25 mm is usually left between the pillar and the furnace wall for the thermal expansion of the brick masonry.


(6) Converter slag injection port


The converter slag injection population is located on the side of the furnace end wall or the side wall is at the end of the furnace head, and the size is 300mm*390mm. When the converter slag is injected, it generally enters the receiving vessel and then flows into the injection port through the launder. The inclination of the flow cell is generally 3° to 5°.


(7) Bronze and copper outlet


The matte outlet is usually located at the back of the side wall, and there are two types of straight and siphon. Straight-type type leaves a small hole at the boundary between the side wall and the bottom of the furnace. The inner wall of the small hole is made of aluminum-magnesia brick, and the outer wall is pressed with a cast iron plate. A small hole with a diameter of 45 mm is left on the plate to align with the brickwork. When the ice copper is not placed, it is blocked with refractory mud, and the hole is opened when the copper is placed. Generally set 2 to 3 ice-copper discharges, used in turn.


In order to reduce the trouble of getting through and blocking, use the siphon to put ice copper. The ice absorbing copper is easy to operate, and the labor intensity is small, and it is inspected once a year.


(8) slag outlet


The slag outlet is generally located at the rear wall of the furnace and also at the side wall of the tail. The position of the slag outlet should be above the matte surface, generally 0.8~1.2m from the bottom of the furnace, and the section is 0.5mX0.9m. The lining near the slag opening is made of aluminum-magnesia brick, magnesia brick or chrome-magnesia brick. A slag dam is built with refractory mud under the slag outlet to adjust the level of the slag surface.


(9) exhaust flue


The flue duct is located at the end of the furnace and has two forms: a direct flue and a diagonal flue. The latter has less resistance to airflow, where soot can settle and reduce the smoke rate. The side walls of the flue are made of refractory bricks, and the top is also useful for ceilings. To reduce flue failure, the flue is usually made wide and short. In order to regulate the air flow, a gate is provided in the flue.


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