Large copper- nickel smelting electric furnaces generally use a rectangular electric furnace, which is composed of an electric furnace body and ancillary equipment.
1) The main components of the rectangular electric furnace body of the furnace body are: furnace base and furnace bottom, furnace wall, furnace top, steel skeleton, feeding device, melt discharge port, smoke exhaust system, temperature measuring device and power supply system, etc. Shown.
(1) Furnace base and furnace bottom. The temperature of the bottom of the mine electric furnace is relatively high and requires good ventilation and cooling. Therefore, the electric furnace base consists of several heat-resistant reinforced concrete pillars (96 in a domestic factory). The pillars are generally higher than 1.7 m, which is convenient for air circulation cooling and observation furnace. Bottom situation. The surface of the pillar is inclined to the side of the safety pit to ensure that the high temperature melt smoothly flows into the safety pit when the furnace is in an accident. Laying the beam above the beam strut pairs, the layer thickness which laid a steel sheet (# 40 using domestic factory beam, plate thickness of 40mm), magnesium deposits on the steel sheet masonry clay bricks hearth furnace The bottom is inverted arched to prevent the bottom of the furnace from floating up after the melt intrusion. The bottom of the furnace is raised by 100 to 200 mm per meter. The bottom of the furnace is mainly composed of clay brick layer and magnesia brick, and a 30-50 mm magnesia layer is left between the two layers. [next]
(2) Furnace wall. The outer shell of the furnace wall is generally made of steel plate of 30 to 40 mm thick, and refractory brick is built inside. Due to the high temperature zone furnace concentrated near the electrode, the bath common zone of the furnace wall or chromium magnesite brick masonry magnesia brick, chamotte brick outermost layer, over the whole slag line refractory brick, masonry furnace wall are wet The wall has a certain expansion joint. In order to extend the life of the furnace, in recent years, some factories have not installed a cooling water jacket around the furnace wall, and the effect is very good. Since there is no melt discharge port at both ends of the furnace, the furnace lining is easily damaged, so the end wall is thicker than the side wall. The working walls and explosion-proof holes are provided on both sides of the wall, which is convenient for opening and stopping the furnace and observing the high-pressure gas in the furnace of the furnace.
(3) The top of the furnace. Because the furnace space temperature is not high iron furnace, generally arch roof with 300mm thick wedge into high aluminum refractory brick. The top of the furnace is provided with an electrode insertion hole and a return hole of the converter slag along the center line of the furnace. There are also feeding holes and exhaust holes on both sides of the center line. Due to the large number of holes in the top of the furnace, these parts are constructed of shaped bricks. After the top brick is built, the aluminum steel fiber low cement castable is poured and poured.
2) Steel skeleton and fastening device In order to make the furnace wall have the necessary rigidity, a steel shell plate with a thickness of 30 to 40 mm is applied to the outside of the brick body. The outside of the panel is reinforced with a skeleton.
The bottom plate of the electric furnace bottom is a reinforced steel plate, which is mounted on the bottom beam, and the bottom beam is supported on the column base.
The inner frame of the electric furnace is composed of a plurality of columns, and the distance between the columns is 1.5 to 20. m. The opposite poles on both sides are tensioned by tie rods, which are respectively passed from above the top of the furnace and under the bottom of the furnace. The ends of the rods are pressed against the beams of the clamped columns by nuts and pin nuts, between the beams and the nuts. It is equipped with a spring to buffer the horizontal thrust generated when the furnace wall and the furnace roof are heated and expanded. The tie rod is connected by a joint made of round steel with a diameter of 50-70 mm.
3) Smoke exhaust system In order to uniformly discharge the flue gas from the furnace, a plurality of smoke holes are usually arranged on the top of the furnace, and the arrangement is determined by the arrangement of the electrodes. After the flue gas passes through a series of purification equipments of flue, cyclone dust collector and electric dust collector, it is sent to acid or empty according to the concentration of flue gas SO 2 .
4) The electric furnace feeding device material is added to the furnace from the mine silo on the top of the furnace. Generally, the scraper transporter on both sides of the top of the furnace is used to transport the material to the small silo, and then the feeding tube is added to the furnace. Material feeding and dosing are carried out using an electric vibrator.
5) Melting product discharge port There are 2 to 4 low-cut nickel ports at one end of the furnace, which are located at different elevations of 200-500mm above the bottom of the furnace. The low nickel bismuth that is smelted in an electric furnace is usually slightly superheated (1200 Â° C). When the superheated nickel crucible is released, when the superheated nickel crucible is released, the brick body near the discharge port is saturated with the low nickel crucible, and the discharge port itself becomes larger in diameter due to corrosion. In order to have a certain diameter of the discharge opening, a refractory bushing is placed on the outside of the hole. The refractory bushing is made of sorghum-resistant chrome-magnesium material and also has a graphite bushing with a hole diameter of 30 mm. Cone bushing fitted detachably discharge outlet, to make a low nickel matte port center and the center of the bush hole brick coincide, and the liner is fixed to the center of it, the tool used was the largest cast iron Rings, long ferrules and wedges, and detachable venting plates are attached to the furnace casing with slats or wedges. [next]
The slag discharge port is generally 2 to 4, and is disposed on the other end of the furnace, and the height from the bottom of the furnace is 1450 to 1750 mm. The elevation of the slag port is lower than the slag surface, which is the lowest part of the slag containing nickel.
6) Temperature measuring device In order to facilitate the observation of the working condition of the furnace, thermocouples are installed in different parts of the furnace wall and the top of the furnace and different depths of the molten pool to measure the change of the greenhouse degree of each part.
7) Cooling of the equipment and dust prevention of the short net (1) Cooling of the bottom of the furnace. The electric furnace bottom and the conductive copper row are provided with ventilation and cooling. Due to the overheating of the nickel crucible, the bottom of the electric furnace may cause leakage of nickel crucible at the bottom of the furnace, and the central part is forced to be ventilated for cooling. Each electric furnace is supplied with a fan for air supply. The operation of the hearth fan depends on the height of the bottom of the furnace. When the temperature is normal (400 ~ 500 Â° C), the cooling air can not pass; if the temperature is too high (more than 600 Â° C), it must be ventilated.
(2) Power supply short net (copper row) cooling. There are two types of conductive copper bars drawn from the transformer side: one is a water-cooled tubular copper tube using circulating water cooling, and the other is a sheet-shaped copper row using ventilation cooling. The sheet-like copper row is externally provided with a sealing cover, so the conductive copper bar must be sealed to prevent short circuit between the pieces due to dust accumulation. The sealing cover is made of a steel plate having a thickness of 1.5 to 2 mm, and is cooled by a cooling air supply to the inside of the cover.
8) Electrode device In order to supply power to the electrodes, each electrode has a set of devices for clamping, supplying power and moving the electrodes. Device for electrode activity. The components held by the electrodes are mainly copper tiles and are supplied to the electrodes by copper tiles. The copper tile is a long-shaped water jacket cooled by a copper curved hollow or a pre-embedded copper tube, and its arc shape coincides with the outer circle of the electrode. At the same level, it is arranged around the electrode shell, generally 6-8 pieces. The upper and lower movable mechanisms of the electrode can be divided into two types: mechanical type and hydraulic type. The mechanical method is to drive the electrode up and down by the hoisting device. The hydraulic method is to lift and lower the plunger of the hydraulic cylinder fixed on the floor. The pressing of the electrodes can also be accomplished by mechanical and hydraulic methods, the former being continued by the steel strip, and the latter being accomplished by multiple sets of hydraulic equipment. Gold-company furnace electrode pressure release systems have been employed laundry hydraulically, from the previous four vertical friction ring, intermediate cylinder, two friction rings and the copper tile wedge from the cylinder to complete, reducing the intermediate cylinder, making the device more For the sake of simplicity. An important problem with electrode devices (including clamping systems, lifting and lowering pressure systems) is the insulation of the electrodes, which should be given adequate attention. It should be ensured that the insulation is safe and reliable under all circumstances.
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