Medium and low carbon ferromanganese smelting process
Cold loading method is the traditional method for the production of low carbon ferromanganese, and the furnace used is tilting graphite arc furnace. The smelting process of medium and low carbon ferromanganese includes furnace filling, arc starting, feeding, melting, refining and iron extraction.
Refining furnace: furnace lining with magnesium materials: lining in the smelting high temperature, by the slag and metal erosion and arc high temperature, furnace bottom and furnace refractory material gradually thin, more easily damaged iron mouth, after the completion of the furnace iron, to immediately block the iron mouth and filling furnace.
Arc starting, feeding and melting: after the completion of filling furnace, first lay a layer of lime extracted from the batch at the bottom of furnace, then add part of manganese silicon alloy for arc starting, and then add the rest of the mixture into the furnace at one time. After the charge is added, the power is fed to full load. In order to reduce the heat loss and shorten the melting period, the charge at the edge of the furnace should be pushed to the electrode and the furnace center in time, but to prevent slag turning and splashing: after the basic melting of the charge (at this time the alloy silicon content has been reduced to 3%-6%, the basicity and manganese content of the slag are also close to the final slag), it will enter the refining period.
Refining: As the slag temperature at the end of melting has reached 1500-1600℃, the desilication reaction has basically ended, so the desilication speed in the refining period slows down. In order to speed up desilication and shorten the refining time, the molten pool should be stirred for several times, and the silicon content of the alloy should be determined by regular sampling to determine the iron time. The silicon content of the alloy is generally controlled within the range of 1. 5%-2.0%. When refining for a period of time, the alloy silicon content is still high, can be added to the furnace some manganese ore and lime, continue refining to silicon content qualified before the furnace: prolong the refining time, can make the manganese content in the slag reduced, but will lead to the loss of manganese volatilization and the increase of electrical energy consumption. Therefore, the manganese content in slag should not be overemphasized.
Iron: when the silicon content of the alloy basically meets the requirements, the power can be cut off for sedation, so that the metal particles in the slag fully settlement, and then iron. When the iron is discharged, the alloy and slag flow into the molten iron ladle together. Due to the mixing effect between the slag and the alloy when the iron is discharged, 0.2%-1.0% silicon can be removed outside the furnace. Hot iron temperature is high, and mixed with slag, not immediately pouring, to prevent burning ingot mold and slag inclusion in the iron, should be calm and cool for a certain time after pouring, using thermal insulation casting covered with slag. The mold depth for casting should not exceed 300mm, otherwise it will cause segregation in the center of the alloy due to too slow cooling, resulting in impurities enrichment, and the product will be scrapped in serious cases.
