Medium and low carbon ferromanganese production method and its smelting principle

In a low carbon manganese iron production methods are silicon thermal power, and the following three Oxygen Furnace shaking method, intermittent operations are used.
1. The electric smelting silicon thermal silicon thermal substance of low-carbon ferromanganese in the submerged arc furnace is produced in the silicon-silicon manganese alloy as a reducing agent, the reduction in the refining furnace manganese oxide ore, and the alloy to be After the silicon is reduced to the specified limit, its product is medium and low carbon ferromanganese.
During the heating process of the manganese ore blended into the charge, the high-valence oxide of manganese gradually decomposes with the increase of temperature to become a low-oxide.

After the manganese ore is thermally decomposed to form Mn ₃ O ₄ , while the temperature rise continues, some of the high-valent oxides directly react with silicon to form low-oxide and manganese metal, and the reaction is 2Mn ₃ O ₄ +Si===6MnO+SiO ₂ ( 1)
Mn ₃ O ₄ +2Si===3Mn+2SiO ₂ (2)
Without reduction of Mn ₃ O ₄ , it thermally decomposes to form MnO and is melted into the slag. Continue to be reduced by silicon in the alloy melt. Its reaction formula is 2MnO+Si===2Mn+SiO ₂ (3)
Due to the formation of (MnO•SiO ₂ ) by the combination of SiO ₂ and MnO, the activity of the reactant MnO is lowered, and the forward reaction becomes difficult. In order to improve the reduction effect of MnO and increase the recovery rate of manganese, it is necessary to A certain amount of lime is added to the furnace to displace MnO from the silicate. The reaction formula is CaO+MnO•SiO ₂ ===MnO+CaO•SiO ₂ (4)
2CaO+MnO•SiO ₂ ===MnO+2CaO•SiO ₂ (5)
The relationship between slag basicity and MnO activity coefficient is shown in the table below.

2. Shaking furnace method Smelting medium-low-carbon ferromanganese is a new energy-saving smelting technology developed after the 1970s. The method of using the furnace for medium-low carbon ferromanganese pre-refining is called electric furnace. The method of using a shaker for directly producing low-carbon ferromanganese is used as a furnace silicon thermal method.
(1) Shaker electric furnace method Shake furnace electric furnace method is the main method of smelting and smelting application. The basic premise of implementing the electric furnace electric furnace method is the linkage of three furnaces. The production process is shown in Figure 1.

First, the manganese slag in the by-product of the refining furnace is fed into the shaker, and the liquid manganese-silicon alloy produced by the submerged arc furnace is then fed into the shaker.
The kiln is shaken at a speed of 55~60r/min. Under good kinetic conditions, the MnO in the manganese slag is reduced by silicon in the manganese-silicon alloy, and the chemical heat released by the reverse switching ensures that the smelting proceeds normally. See the chemical reaction equation. Reaction (3). The MnO in the slag is depleted to the specified requirements, and the poured slag is used for the production of building materials after water quenching. The liquid alloy is poured into the refining furnace until the qualified medium carbon ferromanganese is refined; in the refining furnace The chemical reaction is the same as the electrothermal method. [next]
(2) Shake Silicon Thermal Method The low-carbon ferromanganese produced by the furnace silicon thermal method was firstly produced and put into normal production by Japan's Mizushima Ferroalloy. Two ferroalloy plants in China have also been tested and succeeded. It is to first put the manganese ore and lime preheated in the shaft furnace to 600~800 °C into the shaker, then into the liquid manganese-silicon alloy produced by the submerged arc furnace, and start the shaker at a rock speed of 1~65r/min. During operation, the shaking speed is gradually increased depending on the severity of the chemical reaction in the furnace. The main reduction reaction formula of manganese oxide is 2Mn ₂ O ₃ +Si===4MnO+SiO ₂
2MnO+Si===2MnO+SiO ₂
Most of the desiliconization reaction is completed in the process of heat-for-manganese-silicon alloy, and a small part is continued by the full agitation of the shaker. After the silicon in the alloy is substantially oxidized, the reaction tends to be calm when the furnace is tilted, and the poured slag liquid is condensed and then crushed for use in the ore furnace to smelt the manganese silicon alloy. After the liquid alloy is cast, the grades are neatly stacked.
3. Oxygen blowing method (1) Oxygen decarburization method, oxygen decarburization method, production of medium and low carbon ferromanganese, liquefied high-carbon ferromanganese smelted by blast furnace or ore electric furnace as raw material, heat to the converter, blown by oxygen lance Into oxygen, oxidizing the smelting process of carbon in high carbon ferromanganese. Industrial tests were successfully carried out in China from 1975 to 1978.
When the ambient temperature is lower than 1300 °C, the oxide stability of each element of high carbon ferromanganese is arranged in the order of Si, Mn, C, P, Fe. As the temperature increases, the order of the order changes; the oxygen decarburization method is When the temperature is higher than 1670 ° C or higher, the stability of CO is greater than that of Si, Mn, Fe. On the basis of inhibiting the excessive oxidation of Mn element, carbon dioxide is removed and manganese is produced to produce medium-low carbon ferromanganese.
The main chemical reaction formula of oxygen blowing decarburization method is

The relationship between the change of free energy of each element and the temperature is shown in Fig. 2.

Reasonable temperature control during the blowing process is the key. When the bath temperature is lower than 1550 °C, the carbon and manganese elements are mainly oxidized into the slag; when the bath temperature is higher than 1850 °C, the manganese element volatilizes above 4%, especially at the center. The liquid temperature in the oxygen flame zone is as high as 2200~2700 °C, causing a large amount of manganese to volatilize. The actual production requires that the bath temperature be controlled within the range of 1650~1850 °C. When the temperature is too high, the coolant (medium carbon ferromanganese) should be added. At the end of the blowing, the amount of manganese oxidized into the slag accounts for about 30% of the manganese content of the high-carbon ferromanganese. The manganese-silicon alloy needs to be added for post-treatment. The baked alloy is cooled after cooling, and the slag is crushed after cooling. Return to the manganese silicon alloy smelting workshop for use.
(2) Oxygen desiliconization method The oxygen desiliconization method is based on the liquid manganese-silicon alloy produced by the ore-heating electric furnace as the raw material, and is heated into the converter, and the silicon in the manganese-silicon alloy is oxidized by the oxygen lance to obtain the medium-low carbon. Ferromanganese. The operating process is similar to the oxygen decarburization process. In 1978, the experiment of low-carbon ferromanganese in the process of liquid oxygen-manganese alloy blowing oxygen desiliconization was successfully carried out. The furnace temperature during the blowing process needs to be controlled at 1500~1600°C. The alkalinity of the slag liquid is 1.5~1.6. Therefore, it is necessary to continuously add dry manganese ore, calcined lime and fluorite to the slag to control the temperature. After the sample is filled with silicon, the furnace is cast and cast, and the high alkalinity manganese slag is discharged. abandoned.

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