Low carbon ferro manganese refers to the carbon content of less than 0.7% ferro manganese alloy, low carbon ferro manganese is smelting high-quality pure steel alloy additives, each production of a ton of high-quality pure steel consumption of low carbon ferro manganese 20Kg, the national annual output of high quality pure steel about 50 million tons, a year about 1 million tons of low carbon ferro manganese.
The traditional low carbon ferro manganese production process is two steps. Two-step production of low-carbon ferro manganese, will be produced by the hot spot furnace of high silicon low carbon silicon manganese alloy silicon as a reducing agent, cold loaded in the refining furnace to reduce manganese oxide in manganese ore, that is, low carbon ferro manganese. The process is a two-step process, the first step is to produce silicon manganese alloy, the second step is to produce low-carbon ferro manganese. The advantages of the two-step method are simple process operation, intermittent process production, one-furnace smelting, easy to control; Its disadvantages are: the utilization rate of silicon is low, 75%; The recovery rate of main element manganese was 80%. Impurity phosphorus content is high.
One step smelting process of low-carbon ferro manganese, that is, slag smelting, shaking, refining three smelting processes into one, concentrated in a furnace body to complete, direct use of manganese ore using electric silicon thermal method, one step to produce low-carbon ferro manganese process. The advantages of one-step method are high thermal energy utilization, the unit power consumption of the product can reduce the power consumption by 30% compared with the two-step method, and the silicon utilization rate is high, which is 95%. The recovery rate of main element manganese is 90%, and the content of impurity phosphorus is less than 0.1%. Its disadvantage is that the smelting furnace affects each other, and the production process control needs to be strict.
Smelting method of low carbon ferro manganese
The slag melting, shaking and refining process is completed in an electric furnace, including the following steps:
1) Slag: the ratio of good manganese ore and lime as the charge (1) add into the electric furnace, power melting charge, wait for the charge to melt into liquid, slag end;
2) Shaking: when the charge in step 1 is turned into a liquid state and the slag temperature reaches 1400°C, stop the power supply, shake the furnace body, add ferro silicon powder to the furnace while shaking, and shake, after the end of the shaking, the slag in the furnace is exhausted, and the micro-carbon silicon manganese generated by shaking is left in the furnace;
3) Refining: After the end of shaking, add manganese ore and lime with a good ratio as the charge, send electricity for production, and start refining. After the charge is basically melted, the alloy ferric water sample is taken from the furnace to determine the silicon content of the alloy. When the silicon in the alloy is less than 1%, the refining is finished and low-carbon ferric manganese is obtained.
One step smelting method of low carbon ferro manganese, in an electric furnace to complete the slag, shaking, refining process, the electric furnace must have the function of refining furnace, but also have the function of shaking furnace, the electric furnace body should be able to tip over, the electric furnace is both refining furnace, but also shaking furnace, but also can tip over.
Low carbon ferro manganese production process control:
① Accurate operation: according to the characteristics of one-step production, it is required to be refined and accurate in the electric furnace smelting operation process; The addition of the charge must be strictly in accordance with the prescribed amount and procedure, and the smelting time of the electric furnace and the load of power transmission must be strictly in accordance with the prescribed amount.
② Shaking operation: Shaking operation is the most important link in the one-step production cycle, and the operation of this link directly affects the smoothness of the subsequent links. When shaking operation, the addition of ferro silicon should be strictly carried out in accordance with the prescribed amount and procedure, the speed of the shaking furnace is controlled at 55-60r/min, and the shaking time is controlled at about 10-15 minutes.
③ Furnace size requirements: the diameter and depth of the furnace have a greater impact on the shaking, and the ratio of depth to diameter should be about 0.8.
(4) Refining desiliconization control: Desiliconization is the main process of refining, when the silicon in the alloy is reduced to 1%, the smelting is over; When refining and desiliconization, we should grasp several links: first, control the appropriate slag manganese; The second is to control the appropriate alkalinity; The third is to expand the reaction contact surface appropriately.
⑤ Slag basicity control: The lining material of one-step smelting of low-micro-carbon ferro manganese is preferably magnesian material, which is alkaline material, so the basicity of the slag liquid must always be kept greater than 1 in the process of one-step smelting of low-carbon ferro manganese.
Iron, slag outlet maintenance: iron, slag outlet is the weakest place in the furnace lining, using tar mud ball protection, blocking iron, slag outlet, can effectively maintain iron, slag outlet.
Safety and environmental protection: safety and environmental protection is the guarantee of production, the main measures to ensure safety are: first, to ensure that the dry material into the furnace, the water content of the charge shall not be greater than 3%; The second is to ensure that the furnace body around dry, no water or damp, the third is to build the furnace to build a circle of safety and leak-proof permanent layer to ensure that the hot metal will not penetrate the furnace. In terms of environmental protection, it is preferable to install a cloth bag dust collector of 15,000 cubic meters to collect flue gas and dust in the smelting process.
The method of smelting low-carbon ferro manganese is characterized by concentrating the three steps of traditional process slag, shaking furnace smelting and electric furnace refining in a furnace to complete, and the three processes of slag, shaking furnace smelting and electric furnace refining are mature to do separately, and the three processes together have become a new process. The three processes together form a relationship of mutual connection, mutual influence and mutual restriction, which is a new production process control method. It has the characteristics of low energy consumption, low carbon ferro manganese main element recovery rate, high effective element utilization rate, low product impurity content, is the innovation of traditional technology, is the technical upgrade of traditional industry, worthy of affirmation and promotion.
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