Smelting operation of the furnace production process

First, shake stove - electric furnace production of low-carbon ferromanganese law of the Act on the basis of the development of our country from abroad, "Niigata Law" (thermal loading) and "Bohlen Law" (Perrin) on the production of low-carbon manganese iron New Technology. Several domestic manufacturers have conducted industrial tests and achieved remarkable results in the country. In summary the manufacturers test the empirical data on the basis of the Beijing Iron and Steel Design Institute designed a rocking furnace - electric furnace method carbon ferromanganese production line, and in 1990 put into operation in Zunyi ferroalloy plant. The production line is designed with a 16500KVA closed reduction furnace for the production of liquid helium manganese silicon alloy, an 8m ³ shaker and a 3500KVA furnace rotary refining furnace. The annual output of medium and low carbon ferromanganese is 20,000t. China's current production of the medium and low carbon ferromanganese production line.
(1) Process principle of shaker pre-refining

The furnace body sits on a cradle. When the cradle is shaken, the kiln is eccentrically moved, and it is tumbling up and down, which produces strong mixing and agitation (see Figure 1), which expands the reaction boundary between the slag and iron. The diffusion rate of the product and the product are increased, so that the reduction oxidation reaction between MnO in the slag and [Si] in the alloy proceeds rapidly.
The shaker-electric furnace method is to convert the liquid manganese-silicon alloy and the liquid medium-manganese slag into a shaker, and perform strong mixing and stirring in the shaker to react the silicon of the manganese-silicon alloy with the MnO in the slag to perform desiliconization and Reduction of manganese. Then, the liquid manganese-silicon alloy after taking off part of the silicon is fed into the refining furnace and smelted together with the preheated manganese ore and lime to produce medium-low carbon ferromanganese. The content of manganese in the slag treated by the shaker is greatly reduced, and it becomes lean slag. It can be used for smelting of manganese-silicon alloy, replacing dolomite, partially replacing silica , or water quenching for building materials.
After pre-refreshing in the furnace, the manganese content in the alloy is increased and the silicon content is reduced. The composition is shown in the table below. This has created favorable conditions for reducing the desiliconization task in refining furnace smelting, shortening the smelting time, and reducing the unit power consumption of the product.

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The production practice data shows that the initial slag basicity R ₁ has a significant effect on the final slag MnO content during the furnace pre-refining process (see Figure 2). The relationship between the two can be expressed by the following formula:
[MnO]=21.45-14.05R ₁ -0.1R ² ₁ +1.6R ³ ₁

As can be seen from Fig. 2, the final slag [MnO] decreases as the initial slag alkalinity increases. The final slag basicity R ₂ also has an effect on the MnO content in the final slag (see Figure 3). The relationship between the two is:
1 When 11% < w(Si) ≤ 12% [MnO] = 29.67-37.24R ₂ + 14.35R ² ₂
2 when 12% < w (Si) ≤ 13%
[MnO]=36.63-48.19R ₂ +18.14R ² ₂
Figure 3 shows that the final slag MnO content decreases as the final slag basicity R ₂ increases.
In order to give full play to the advantages of high desiliconization efficiency of the shaker, it is also possible to add some dry manganese ore to the lower part of the alloy during the pre-refining, which is more advantageous for the subsequent refining furnace refining. [next]
Second, the characteristics of the furnace-electric furnace smelting
A large number of product practices have proved that the production of medium-low carbon ferromanganese by the shaker-electric furnace method has the following advantages compared with the conventional electric silicon thermal method:
(1) The task of desiliconization in the concentrate furnace is alleviated. When using the silicon thermal method, the silicon in the manganese silicon alloy should be reduced from 18% to less than 2%. After pre-refining in the furnace, it only needs to be in the refining furnace. The silicon content in the alloy is reduced from 6% to 12% to less than 2%.
(2) As the desiliconization task is reduced, the amount of SiO ₂ produced in the refining furnace and the amount of added manganese ore and lime are correspondingly reduced, and the amount of slag, power consumption, and manganese content in the slag are reduced.
(3) After pre-mixing with the shaker, the manganese content of the slag in the refining furnace can be appropriately relaxed, and the excess manganese ore can be used for smelting to further accelerate the desiliconization speed.
(4) The liquid manganese-silicon alloy after the pre-refining of the shaker has a large amount of physical sensible heat, which saves the time for the country to re-use electricity and its corresponding power consumption, and the volatilization loss of manganese in the charge is also reduced;
(5) The slag discharged from the refining furnace is pre-refined by the shaker. When it is disposed, the manganese content in the slag is reduced from 12% to 18% to less than 6%, which greatly improves the recovery rate of manganese.
Third, the operation points
The operation process is:
(1) After the previous furnace iron is finished and the eyes are blocked, the electrode is lifted, and then the furnace body is rotated. At the same time, manganese ore and lime are added into the furnace, so that the charge is distributed in a double-peak shape in the furnace. After the charge is added, the furnace stops. The furnace body rotates to allow the charge to preheat in the furnace.
(2) The slag discharged from the refining furnace at a temperature of 1350 to 1400 ° C is metered and then fed into a furnace.
(3) The liquid manganese-silicon alloy slag is taken from the reduction furnace at about 1300 ° C, sampled, weighed, and then poured into a shaker, and mixed with the slag.
(4) Start the shaker rotation mechanism and gradually increase the rotation speed to 55~60r/min. When the solution wave in the furnace reaches the maximum, add appropriate amount of dry manganese ore and lime to the furnace through the hopper, and flexibly control the shaking according to the furnace temperature. time.
(5) After the shaker is shaken for 8 minutes, the iron rod is inserted into the furnace to take the slag sample. When the slag on the iron rod is glass-like and the section is light brown, the rotation speed can be reduced until the shaking is stopped.
(6) Pour the shaker, use the transition trough to pour the liquid slag and molten iron into the slag package heat, and shake the slag as the lean residue.
(7) After pre-refining, the liquid manganese-silicon alloy is slag, metered and transported to the refining furnace for hot exchange. At the same time, the sample is quickly analyzed for silicon content, and the adjustment material is supplemented accordingly.
(8) When the liquid manganese-silicon alloy is heated to the refining furnace, the furnace body should be rotated, so that the alloy melt is distributed along the peaks and valleys of the furnace surface.
(9) After the alloy heat is completed, the furnace body stops rotating and the power is supplied for refining.
(10) When the charge is melted to 70%~80%, the furnace body is started to rotate, and the charge around the furnace wall is manually pushed to the periphery of the electrode and the core to promote rapid melting.
(11) After the furnace material is completely melted, stop rotating the furnace body, sample and test the silicon, and then pass the power out of the furnace after passing the test.
The furnace condition control and tap casting in the refining process are referred to the relevant part of the electric silicon heat method.
The production of medium-low carbon ferromanganese by the shaker-electric furnace method has a short cycle, high production efficiency, low power consumption (400~700 kWh/t), and high recovery rate of manganese (the recovery rate of alkaline slag manganese is about 80%). The low alkalinity slag is more than 90%). This method was quickly promoted in domestic ferroalloy plants. The production of low-carbon ferromanganese produced by this method has already accounted for the total production of low-carbon ferromanganese in China. About half of the time, in order to make full use of manganese ore resources and improve the economic benefits of smelting, we will create a new road.
Fourth, the furnace silicon thermal production of low-carbon ferromanganese manganese ore and quicklime with a particle size of less than 3mm and preheated to 600~800 °C in the shaft furnace is added to the shaker, and then into the liquid manganese-silicon alloy produced by the reduction furnace. High-quality manganese ore and liquid manganese-silicon alloy can smelt qualified medium-low carbon ferromanganese only in the shaker process. In the process of heat exchange of manganese-silicon alloy, at the moment when the alloy is in contact with manganese ore, the silicon in the alloy is in direct contact with Mn ₂ O ₃ in the ore, spontaneously undergoing a redox exothermic reaction, and 60% to 70% of silicon is present. When the heat is completed, it is taken off, and 20%~30% of the silicon is removed after shaking for 20 minutes in the shaker. This method makes full use of the heat released by the reaction of silicon and manganese oxide, and does not require an external heating source, thus saving a lot of energy. After the silicon in the alloy is substantially oxidized, the reaction tends to be calm, and the poured slag liquid is condensed and then crushed for use in the reduction furnace to smelt the manganese silicon alloy. After the liquid alloy is cast, the grades are finely packed.

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