Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
  • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B47/00—Obtaining manganese
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B5/00—General methods of reducing to metals
  • C22B5/02—Dry methods smelting of sulfides or formation of mattes
  • C22B5/12—Dry methods smelting of sulfides or formation of mattes by gases
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/20—Recycling

Definitions

• the present invention relates to a method for producing manganese carbide by reducing and carbonizing manganese ore, and to a method for producing manganese-containing steel using the produced manganese carbide.
• the unit of volume "L” represents 10 -3 m 3
• the symbol "N" added before the unit of gas volume represents the standard state of the gas.
• the standard state is a temperature of 0°C and an atmospheric pressure of 1 atm.
• the pressure unit of 1 atm is 1.01325 x 10 5 Pa.
• the T.Mn (total Mn) in a substance represents the total content of manganese in the substance, regardless of its form.
• Manganese contained in steel is added to molten steel in the steelmaking process to improve the toughness and wear resistance of the steel.
• Manganese-containing substances added in the steelmaking process include metallic manganese, ferromanganese, silicon manganese, etc.
• Ferromanganese is generally produced by charging manganese ore, iron ore, and reducing material into a melting furnace and melting and reducing the manganese ore and iron ore. Since this method involves handling high-temperature molten material, it requires a transport container to contain and transport the molten material and a casting device to cool and solidify the molten material. This raises concerns about the increased size of the equipment and the deterioration of the handleability of ferromanganese products. There is also concern about a decrease in product yield due to the molten material scattering during the reduction process and remaining in the melting furnace.
• Patent Documents 1 and 2 only partially reduce the highly oxidized manganese oxides ( MnO2 , Mn2O3 , etc. ) contained in manganese ore to obtain a less oxidized manganese oxide (MnO).
• MnO2 , Mn2O3 , etc. highly oxidized manganese oxides
• Patent Document 4 a suitable range for the particle size of manganese ore is not disclosed, and in the case of a fine granular or powdered form, there is a concern that the handling property may be deteriorated and the yield of manganese carbide obtained after processing may be reduced. On the other hand, there is a concern that the reaction efficiency of the reduction and carbonization process may be reduced if the particle size is too large.
• the present invention aims to propose a method for producing manganese carbide that can reduce and carbonize manganese ore efficiently in a relatively short time without using multiple reduction treatment devices or needing to finely grind manganese ore, thereby reducing CO2 emissions. Furthermore, the present invention proposes a method for producing manganese-containing steel using the obtained manganese carbide.
• the inventors brought manganese ore into contact with hydrogen gas or hydrocarbon gas at the processing temperature at which the ore is unmolten, thereby carrying out a reduction and carbonization process for the manganese ore, and completed the present invention.
• the method for producing manganese carbide according to the present invention which advantageously solves the above problems, is characterized in that manganese ore is heated to a processing temperature at which it is in an unmolten state, and is brought into contact with a mixed gas of hydrogen gas and hydrocarbon gas under atmospheric pressure, thereby carrying out a reduction and carbonization process on the manganese ore.
• the method for producing manganese carbide according to the present invention is as follows: a. setting the partial pressure of the hydrocarbon gas in the mixed gas to 10.0 kPa or more, and setting the number of hydrogen atoms in the mixed gas to 12 times or more the number of carbon atoms; b.
• the treatment temperature is in the range of 800° C. or higher and lower than the melting temperature Tm ; c. Furthermore, the particle size of the manganese ore is adjusted in advance to 3 mm or more and 100 mm or less; d.
• the reduction and carbonization treatment is carried out in a rotary kiln; e. Supplying the mixed gas from a position where the temperature inside the rotary kiln is 700° C. or higher; f.
• the partial pressure of the hydrocarbon gas in the mixed gas is 10.0 kPa or more, and the number of hydrogen atoms in the mixed gas is 12 times or more the number of carbon atoms; g.
• the maximum temperature inside the rotary kiln is in the range of 800 ° C. or higher and lower than the melting temperature Tm ; etc. may be more preferred embodiments.
• the melting temperature Tm is the temperature at which a solid sample changes into a liquid, and is preferably determined by any one of the following first to third methods because it is easy to do so, but is not limited to these methods.
• the first method is to place a solid sample in a container such as a crucible, and in the target gas atmosphere, use an electric resistance furnace or the like to raise the temperature at a rate of 5°C per minute, preferably 1°C per minute or less, while continuously observing the sample inside the container, and determine the melting point as the temperature at which the gaps between the grains of the solid sample disappear and a smooth surface appears on the surface.
• the second method is to measure the temperature by differential thermal analysis in a target gas atmosphere at a rate of 5°C per minute, preferably 1°C per minute or less, and to determine the melting point as the temperature of the minimum point of the endothermic peak.
• the measurement is stopped at the temperature at which each endothermic peak occurs, the appearance of the measured sample is observed, and the melting point is determined as the lowest temperature of the minimum point of the endothermic peak at which the gaps between the grains of the solid sample disappear and a smooth surface appears on the surface.
• the third method is to use a thermodynamic calculation software on a computer, input the sample composition, change the temperature and calculate the liquid phase ratio, and define the temperature at which the calculated liquid phase ratio exceeds 95% as the melting point.
• the method for producing manganese-containing steel according to the present invention is characterized by including a step of adding manganese carbide produced by any of the above production methods to molten steel.
• the present invention when manganese ore is reduced and carbonized, it is possible to efficiently reduce and carbonize the manganese ore in a relatively short time without using multiple reduction treatment devices, without the need to finely grind the manganese ore, and without melting the manganese ore. Furthermore, it is possible to reduce CO2 emissions during the reduction and carbonization.
• manganese carbide refers to a manganese compound in which manganese ore is reduced, the oxygen concentration in the manganese compound falls to a predetermined value or lower, and the carbon concentration is within a predetermined range.
• Mn in manganese ore exists mainly in the form of MnO2 . Therefore, when only hydrogen gas is used, MnO2 is only reduced to MnO, as shown in the following chemical formula 1 (1) to (3). It is thermodynamically difficult to reduce manganese ore to metal using only hydrogen gas.
• the composition of the mixed gas of hydrogen gas and hydrocarbon gas to be contacted with the manganese ore is preferably within the following range.
• the partial pressure of the hydrocarbon gas in the mixed gas is set to 10.0 kPa or more.
• the partial pressure of the hydrocarbon gas in the mixed gas supplied there is no upper limit on the partial pressure of the hydrocarbon gas in the mixed gas supplied.
• the number of hydrogen atoms in the mixed gas is set to 12 times or more the number of carbon atoms. If the number of hydrogen atoms in the mixed gas contacted with the manganese ore is less than 12 times the number of carbon atoms, the hydrogen gas concentration in the mixed gas may be too low. Therefore, as described above, the ratio of hydrocarbon gas consumed in the reduction reaction from MnO2 to MnO increases, which may lead to an increase in CO2 emissions.
• the ratio of the number of hydrogen atoms to the number of carbon atoms in the mixed gas there is no upper limit on the ratio of the number of hydrogen atoms to the number of carbon atoms in the mixed gas, but the higher this value, the lower the ratio of hydrocarbon gas in the mixed gas, which may make it difficult for the carbonization reaction of MnO to proceed. Therefore, it is more preferable to set the number of hydrogen atoms in the mixed gas to 22 times or less the number of carbon atoms.
• Patent Document 3 discloses that the carbonization start temperature of MnO by a mixed gas of hydrogen gas and methane gas is 1870°C. However, as a result of the inventors repeatedly carrying out the reduction and carbonization treatment of manganese ore by hydrogen gas and hydrocarbon gas, they found that manganese carbide can be obtained even at a temperature lower than 1870°C.
• the carbonization reaction of MnO by hydrocarbon gas starts from about 750°C.
• the higher the treatment temperature the more the reduction reaction of MnO2 and the carbonization reaction of MnO are promoted. Therefore, it is more preferable to set the temperature at 1100°C or higher. If the treatment temperature is higher than the melting temperature Tm of the manganese ore, the air permeability will deteriorate due to melting, and there is a risk of inhibiting the reduction and carbonization reaction. From the viewpoint of energy saving, the treatment temperature of the reduction and carbonization treatment is more preferably 1200° C. or less.
• the manganese carbide obtained by the above method is added to molten steel in any step in the manufacturing process of molten steel.
• ferromanganese is used in the steelmaking process in the manufacturing process of molten steel.
• Ferromanganese is classified into high carbon-, medium carbon-, low carbon-, and very low carbon-ferromanganese according to the carbon content, and is used according to the steel component standard and manufacturing process.
• high carbon-ferromanganese contains about 7 mass% C, and C in ferromanganese exists in the form of manganese carbides such as Mn 7 C 3 and Mn 5 C 2.
• Manganese carbide obtained by the manufacturing method of manganese carbide conforming to the present invention mainly contains Mn 7 C 3 and Mn 5 C 2.
• Manganese carbide conforming to the present invention can be used as a manganese source in the primary refining and secondary refining of molten steel, similar to high carbon-ferromanganese.
• the manganese ore used as the raw material is charged into a reaction vessel for reduction and carbonization treatment.
• a continuous reaction vessel such as a blast furnace or a batch reaction vessel such as a rotary kiln can be used.
• a particle size of the manganese ore there are no restrictions on the particle size of the manganese ore, but since there are concerns that fine granular or powdered manganese ore may reduce the addition yield and make handling difficult, a particle size of 3 mm or more is preferable. If the particle size is too large, there are concerns that the reaction efficiency of the reduction and carbonization treatment may decrease, so a particle size of 100 mm or less is preferable.
• the properties of the manganese ore are not limited. Hydrogen gas and hydrocarbon gas are supplied as reducing gas into the reaction vessel, and the supply amount of each gas is controlled so that the desired gas composition is obtained in the reaction vessel.
• the gas supply method is not limited, and a mixed gas of hydrogen gas and hydrocarbon gas may be used, or hydrogen gas and hydrocarbon gas may be supplied from independent blowing ports.
• a method of blowing reducing gas from a tuyeres installed on the bottom or side of the reaction vessel, or a method of blowing reducing gas using a lance from above the manganese ore layer filled in the reaction vessel can be applied.
• the inside of the reaction vessel is heated to a predetermined processing temperature within a range in which the manganese ore does not melt.
• the method of heating the manganese ore and the reaction vessel is not limited, and burner heating, electric resistance heating, induction heating, etc. can be applied.
• the manganese ore reduced and carbonized in the above process becomes a manganese carbide product.
• the use of the manganese carbide product is not limited, but for example, it can be added to molten steel as a manganese source in the molten steel manufacturing process.
• Mn concentration in molten steel can be adjusted by adding manganese during ladle refining after steel is tapped from a converter, for example during arc heating or vacuum degassing.
• the molten steel with the adjusted composition can be made into steel billets by continuous casting or the like, and can be subjected to surface treatments such as hot rolling, heat treatment, cold rolling, annealing, and plating as necessary to produce manganese-containing steel.
• Example 1 An example in which manganese ore A in Table 1 was reduced and carbonized using a 10 kg electric resistance furnace will be described. After adjusting the output of the electric resistance furnace to raise the temperature inside the electric resistance furnace to a predetermined temperature, 10 kg of a sample of manganese ore A with a particle size of 1 to 5 mm was charged into the electric resistance furnace. Various conditions are shown in Table 2. The T.Mn concentration in manganese ore A before reduction and carbonization was 51.2 to 55.8 mass%. The T.Mn concentration is the total manganese concentration in the manganese ore. Next, in the levels of treatment No.
• samples of manganese ore A with particle sizes of 1 mm and 3 mm were prepared by crushing samples of manganese ore A with particle sizes of 5 mm with a roll crusher.
• a manganese ore sample with a particle size of 5 mm was used, and only hydrogen gas (treatment No. 13) or only methane gas (treatment No. 14) was supplied.
• treatment No. 15 the reduction and carbonization treatment was carried out using coke as a solid carbon-containing material. When coke was used, the amount of coke charged was 5 kg, and Ar gas was supplied at a flow rate of 30 NL/min from a tuyere installed on the side of the reaction vessel.
• a manganese ore A sample with a particle size of 5 mm was used, and reduction and carbonization treatment was carried out using a mixed gas of hydrogen gas and methane gas while maintaining the temperature inside the electric resistance furnace at 1300° C.
• a gas chromatograph analyzer was installed in a part of the gas exhaust system of the electric resistance furnace, and the CO concentration and CO2 concentration in the gas discharged outside the electric resistance furnace were measured.
• the manganese ore sample is removed from the electric resistance furnace and cooled in air, and the oxygen and carbon concentrations in the sample are analyzed by a combustion method, and the concentrations of elements other than oxygen and carbon in the sample are analyzed by a fluorescent X-ray analysis method to investigate the reduction state of the sample.
• the reduction and carbonization treatment conditions of the manganese ore and the reduction rate of the manganese ore are shown in Table 2.
• the reduction rate of the manganese ore in Table 2 is expressed as a percentage of the ratio of the difference between the oxygen concentration of manganese oxide in the manganese ore before reduction and carbonization treatment and the oxygen concentration of manganese oxide in the manganese compound after reduction and carbonization treatment.
• the oxygen concentration of manganese oxide in the manganese ore is the difference between the analytical value of the oxygen concentration of the entire manganese ore sample and the calculated total value of the oxygen concentration of oxides other than manganese in the manganese ore.
• the CO2 concentration in the exhaust gas in Table 2 is the sum of the average value of the CO2 concentration measured during the reduction and carbonization treatment and the average value of the CO2 concentration measured during the reduction and carbonization treatment converted to CO2 concentration.
• H2 represents the hydrogen gas concentration
• CH4 represents the hydrocarbon gas concentration
• PCH4 represents the partial pressure of the hydrocarbon gas
• H/C represents the ratio of the number of hydrogen atoms to the number of carbon atoms in the mixed gas.
• T.Mn represents the total manganese concentration
• O represents the oxygen concentration
• C represents the carbon concentration.
• Tr represents the treatment temperature of the reduction and carbonization treatment
• tr represents the treatment time of the reduction and carbonization treatment.
• d represents the particle size of the manganese ore sample
• tb represents the processing time of the pretreatment of the manganese ore sample, that is, the processing time required to prepare manganese ore samples with particle sizes of 1 mm and 3 mm.
• Example 2 An example will be described in which manganese-containing molten steel was produced in a 50 kg-scale induction melting furnace using manganese carbide obtained in the process Nos. 1 to 12 of Example 1. After 50 kg of high-purity electrolytic iron was charged into the induction melting furnace, the output of the induction melting furnace was adjusted to melt the high-purity electrolytic iron in the induction melting furnace. With the temperature of the molten steel in the induction melting furnace maintained at 1600 to 1620°C, manganese-containing molten steel was produced by adding manganese carbide obtained in the process Nos. 1 to 12 of Example 1 to the molten steel to produce manganese-containing molten steel. As a reference example, high carbon-ferromanganese was added (process No.
• the molten steel was taken from the induction melting furnace and cooled with water to prepare steel samples.
• the carbon concentration in the samples was analyzed using the combustion method, and the concentrations of elements other than carbon were analyzed using ICP atomic emission spectrometry to investigate the composition of the samples.
• the Mn concentration in the molten steel was 0.95 mass%
• the C concentration was 0.095 mass%
• the Si concentration and sol. Al concentration were both less than 0.01 mass%. Therefore, it was confirmed that the composition was similar to that of manganese-containing molten steel produced using a method conforming to the present invention.
• Example 3 An example will be described in which manganese ore B in Table 1 was reduced and carbonized using a rotary kiln with a processing capacity of 100 kg/hr. After the maximum temperature in the rotary kiln was raised to a predetermined temperature using a propane gas burner, 100 kg of a sample of manganese ore B with a particle size of 1 to 120 mm was charged into the rotary kiln. Various conditions are shown in Table 4-1. The flow rate of propane gas for the burner was 20 NL/min, and the flow rate of oxygen gas for the burner was 100 NL/min. The T.Mn concentration in manganese ore B before reduction and carbonization was 50.3 to 54.7 mass%.
• the T.Mn concentration is the total manganese concentration in the manganese ore.
• treatment No. In the levels 21 to 31 and 35 to 37, a lance was inserted into a predetermined position in the rotary kiln, and a mixed gas of hydrogen gas (H 2 ) and methane gas (CH 4 ) was supplied at a flow rate of 2000 NL/min using the lance. After that, the reduction and carbonization treatment was performed by holding for a predetermined time. At this time, the particle size of the manganese ore, the insertion position of the lance, the composition of the supply gas, and the maximum temperature in the rotary kiln were variously changed to perform the reduction and carbonization treatment.
• a manganese ore sample with a particle size of 10 mm was used, and the lance was inserted into a position where the temperature in the rotary kiln was 650°C, and only hydrogen gas (treatment No. 32) or only methane gas (treatment No. 33) was supplied.
• treatment No. 34 the reduction and carbonization treatment was performed using coke as a solid carbon-containing material.
• the amount of coke charged was 25 kg, a lance was inserted at a position where the temperature in the rotary kiln was 650 ° C, and Ar gas was supplied at a flow rate of 2000 NL / min using the lance.
• a manganese ore sample with a particle size of 10 mm was used, a lance was inserted at a position where the temperature in the rotary kiln was 650 ° C, and a reduction and carbonization treatment was performed using a mixed gas of hydrogen gas and methane gas, and the maximum temperature in the rotary kiln was maintained at 1300 ° C.
• a gas chromatograph analyzer was installed at the lance insertion position of the rotary kiln and in a part of the gas exhaust system, and the H2 concentration and CH4 concentration at the lance insertion position in the treatment equipment, and the CO concentration and CO2 concentration in the gas discharged outside the treatment equipment were measured.
• the manganese ore sample was removed from the treatment facility and cooled in air, and the oxygen and carbon concentrations in the sample were analyzed by a combustion method, and the concentrations of elements other than oxygen and carbon in the sample were analyzed by a fluorescent X-ray analysis method to investigate the reduction state of the sample.
• the manganese ore reduction and carbonization treatment conditions and the reduction rate of the manganese ore are shown in Table 4-2.
• the reduction rate of the manganese ore in Table 4-2 is expressed as a percentage of the ratio of the difference between the oxygen concentration of manganese oxide in the manganese ore before reduction and carbonization and the oxygen concentration of manganese oxide in the manganese compound after reduction and carbonization to the oxygen concentration of manganese oxide in the manganese ore before reduction and carbonization.
• the oxygen concentration of manganese oxide in the manganese ore is the difference between the analytical value of the oxygen concentration of the entire manganese ore sample and the calculated total value of the oxygen concentration of oxides other than manganese in the manganese ore.
• Y Mn in Table 4-2 represents the total manganese yield, and represents the percentage of the ratio of the product of the weight of the manganese ore sample after reduction and carbonization and the total manganese concentration to the product of the weight of the manganese ore sample before reduction and carbonization and the total manganese concentration.
• the CO 2 concentration in the exhaust gas in Table 4-2 is the sum of the average value of the CO 2 concentration measured during reduction and carbonization and the average value of the CO concentration measured during reduction and carbonization converted to CO 2 concentration.
• H 2 " in the "reducing gas flow rate” column represents the hydrogen gas flow rate
• CH 4 " represents the hydrocarbon gas concentration
• H 2 " in the "gas composition at the lance insertion position” column represents the hydrogen gas concentration
• CH 4 " represents the hydrocarbon gas concentration
• P CH4 " represents the partial pressure of the hydrocarbon gas
• H/C represents the ratio of the number of hydrogen atoms to the number of carbon atoms in the mixed gas.
• T.Mn represents the total manganese concentration
• O represents the oxygen concentration
• C represents the carbon concentration.
• Tg represents the temperature at the position where the reducing gas or Ar gas is supplied
• Tr represents the maximum temperature in the reduction and carbonization treatment
• tr represents the treatment time of the reduction and carbonization treatment
• d represents the particle size of the manganese ore sample.
• the temperature at the insertion position of the lance was 650°C
• the particle size of the manganese ore sample was 10 mm
• the maximum temperature in the rotary kiln was the same as that of 750°C.
• the reduction rate of the manganese ore was improved to 89% or more, as compared with the treatment No. 22 and 28.
• the partial pressure of the hydrocarbon gas in the mixed gas was 10.0 kPa or more
• the number of hydrogen atoms in the mixed gas was 12 times or more the number of carbon atoms.
• the ratio of the number of hydrogen atoms to the number of carbon atoms in the mixed gas became too small, and it was confirmed that the CO2 concentration of the exhaust gas increased, as compared with the treatment No. 22 and 27.
• Example 4 An example will be described in which manganese-containing molten steel was produced in a 50 kg-scale induction melting furnace using manganese carbide obtained in the process Nos. 21 to 31 of Example 3. After 50 kg of high-purity electrolytic iron was charged into the induction melting furnace, the output of the induction melting furnace was adjusted to melt the high-purity electrolytic iron in the induction melting furnace. With the temperature of the molten steel in the induction melting furnace maintained at 1600 to 1620°C, manganese-containing molten steel was produced by adding manganese carbide obtained in the process Nos. 21 to 31 of Example 3 to the molten steel to produce manganese-containing molten steel. As a reference example, high carbon ferromanganese was added (process No.
• the molten steel was taken from the induction melting furnace and cooled with water to prepare steel samples.
• the carbon concentration in the samples was analyzed using the combustion method, and the concentrations of elements other than carbon were analyzed using ICP atomic emission spectrometry to investigate the composition of the samples.
• the Mn concentration in the molten steel was 0.97 mass%
• the C concentration was 0.091 mass%
• the Si concentration and sol. Al concentration were both less than 0.01 mass%, and it was confirmed that these were approximately the same as the composition of manganese-containing molten steel produced by a method conforming to the present invention.
• the technology disclosed in the present invention can easily produce manganese carbide and can also be applied to the production of high-carbon ferromanganese.

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