MXPA99006921A - Operation management method of iron carbide production process - Google Patents

Abstract

An operation management method of a production process for obtaining an iron carbide having a target composition in two stages of reaction procedures, comprising conducting a second reaction operation for executing remaining reduction and carburization operations after a first reaction operation for partly reducing an iron-containing raw material for producing iron, collecting a solidified sample at an outlet of a reaction furnace after the first reaction operation, measuring a reaction rate of the solidified sample, and controlling an IC rate after the second reaction operation by controlling parameters capable of changing the reduction rate of the first reaction operation.

Description

METHOD FOR HANDLING AN OPERATION OF THE IRON CARBIDE PRODUCTION PROCESS TECHNICAL FIELD The present invention relates to a method for establishing the appropriate process conditions in the production of iron carbide suitable for a raw material for the manufacture of iron and for the manufacture of steel which comprises iron carbide (Fe3C) as the component principal, for example, a raw material for the manufacture of steel that is used in an electric furnace and the like.

ANTECEDENTS OF THE TECHNIQUE Steel production typically involves the steps of converting iron ore to pig iron using a blast furnace, and subsequently converting pig iron to steel using an open hearth furnace or converter. Such a traditional method requires large amounts of energy and equipment on a large scale, and has a high cost. Therefore, a small-scale steel fabrication, has been used a method that comprises the steps of directly converting the iron ore into raw materials used in the steelmaking furnace, and of converting the raw material into steel using a electric oven and similar. With respect to the direct steelmaking process, a direct reduction process has been used to convert iron ore into reduced iron. However, the reduced iron produced by the direct reduction process is highly reactive and reacts with the oxygen in the air to generate heat. Therefore, it is necessary to seal the reduced iron with an inert gas, or by some other measures, during transport and storage of the reduced iron. According to this, iron carbide (Fe3C) which contains a comparatively high amount of iron (Fe), which has a low reaction activity and which can be easily transported and stored, has recently been used as the material containing iron for the manufacture of steel in an electric furnace and the like. In addition, a material for the manufacture of iron or for the manufacture of steel containing iron carbide as the main component is not only easy to be transported and stored, but also has the advantage that the coal combined with the iron element it can be used as a source of fuel in a furnace for iron making or steelmaking, and can be used as a source to generate microbubbles that accelerate the reaction in the steelmaking furnace. Therefore, the raw materials for the manufacture of iron and for the manufacture of steel containing iron carbides as the main component have recently attracted special interest. According to a conventional method for producing iron carbide, fine-sized iron ore is charged into a fluidized-bed reactor or the like, and is reacted with a gas mixture comprising a reduction gas (e.g., gas). hydrogen) and a carburization gas (e.g., methane gas and the like) at a predetermined temperature. In this way, iron oxides (for example hematite (Fe203), magnetite (Fe304), wustite (FeO)) in iron minerals are reduced and carburized in a simple process (which means a process carried out by introducing in a way, simultaneously a reduction gas and a carburization gas to a simple reactor). The prior art in the field of the present invention has been described, for example, in the publication Number 6-501983 of the Japanese translation of the International Patent Application (PCT / US91 / 05198). The process for producing iron carbide can be expressed by the following general reaction formula. 3Fe203 + 5H2 + 2CH4 > 2Fe3C + 9H20 However, in the simple process the reduction reaction and the carburization reaction must be taken together into consideration. Additionally, a reaction gas composition and a reaction gas temperature that are suitable for each reaction can not be applied. As a result, a reaction time (the one that is required for the conversion into iron carbide) becomes longer. As compared to a conventional method, it takes a longer time to obtain a constant amount of raw materials for steelmaking. For this reason, there is a disadvantage in that the scale of the equipment must be increased to increase the production per unit of time. The inventors of the present have filed a patent application (Japanese Patent Application Number 8-30985) relating to novel technology for a method and apparatus for producing iron carbide, which can perform various actions for each operation, increase flexibility as a process, shorten a reaction time and reduce an amount of a reaction gas that is used. This invention relates to a method for producing iron carbide comprising the steps of performing a first step reaction process to carry out a portion of the iron ore reduction reaction comprising hematite as the main component and then performing a second stepwise reaction process to carry out the further reduction and carburization reaction and which has eliminated all the disadvantages of the conventional method for producing iron carbide and which is a transcendental manufacturing method for producing iron carbide. However, also in the case where the iron carbide is produced in the two-step reaction process, it is not always possible to obtain an iron carbide product having an objective composition. The reason is as follows. Many of the reaction parameters such as a reaction gas composition, a reaction temperature, a reaction pressure and the like are related to the generation of the iron carbide. In some cases, the reaction parameters are slightly changed in such a way that unwanted products (which have a low conversion rate to iron carbide, for example) are obtained. If the reaction parameters come out of a constant range, free carbon is sometimes generated. A method has been proposed to control the quality of an iron carbide product characterized in that if the composition of a product obtained can be allowed or not, it is verified by the Móssbauer analysis method in order to control a composition of a product. of iron carbide within a constant range, and the reaction parameters are changed if the composition is not maintained within a tolerance. (For example, see U.S. Patent Number 5073194, PCT / US91 / 05188). However, the Móssbauer analyzer has a disadvantage that takes a longer time (1 to 4 hours) to perform the measurement in order to increase the accuracy. Therefore, there has been a problem that it is impossible to take the appropriate actions that correspond to the conditions in a reactor which are momentarily changed. In consideration of the aforementioned problems of the state of the art, it is an object of the present invention to provide a method for handling an operation of a production process to obtain an iron carbide product having a target composition in a reaction process. of two stages.

BRIEF DESCRIPTION OF THE INVENTION In order to obtain the aforementioned object, the present invention is characterized in that a reduction ratio obtained after a first process by reaction steps is changed on the basis of the knowledge that the reduction ratio obtained after the first process of step reaction and a proportion of iron carbide (hereinafter referred to as a proportion of CH) obtained after a second stepwise reaction process has a correlation between them, thereby regulating the proportion of CH obtained after the second process of reaction in stages. The present invention provides a method for managing an operation of a process for producing iron carbide, comprising the steps of performing a first step reaction process to partially reduce several of the iron-containing materials for the manufacture of iron, and then carrying out a second stepwise reaction process to carry out the reduction and further carburization, is characterized in that a solid sample at the outlet for the first stepwise reaction process is taken to measure a reduction ratio of the sample solid, and a parameter capable of changing the reduction ratio of the first stage reaction process is adjusted to adjust a proportion of CH obtained after the second reaction process per stage. In general, if the reduction ratio of the first step reaction process is decreased, the time required to generate iron carbide in the second stage reaction process is increased. On the other hand, if the reduction ratio of the first step reaction process is increased, the time required for the iron carbide generation in the second stage reaction process is shortened. More specifically, in the case where a material containing iron predetermined for the manufacture of iron is reduced and carburized in the two-step reaction process, assuming that a reaction time is established constant, the proportion of CH obtained after the second process reaction rate per stage is decreased if the reduction ratio of the first step reduction process of the reaction process decreases, and the proportion of CH obtained after the second step reaction process increases if the reduction ratio of the first process of reaction in stages. According to this, the proportion of CH obtained after the second stage reaction process can be controlled by regulating the parameters capable of changing a reduction ratio of the reaction process in stages, ie a reaction temperature, a reaction pressure , a composition of the gas, a bed height of a fluidized bed and the like as described above. Examples of a safe method for measuring a reduction ratio of a solid sample include a method for analyzing a composition of a solid. However, X-ray diffraction or the like takes a long time to perform the measurement. Therefore, it is preferable that a ratio between the magnetic permeability and a reduction ratio must be previously obtained and a magnetic permeability must be measured on the basis of the ratio, whereby a reduction ratio is conveniently and quickly obtained . Also, the solid sample can be taken between the last and middle chambers of the reactor for the first stepwise reaction process instead of the solid sample at the reactor outlet for the first stepwise reaction process, and the parameter capable of changing the reduction ratio of the first stage reaction process corresponding to the correlation between the reduction ratio of the solid sample and the reduction ratio obtained after the first stage reaction process, thus adjusting the proportion of CH obtained after the second stage reaction process. In the case where the interior of a reactor for the first stage reaction process is divided into several chambers, a change in the conditions of a material containing feed iron can be detected early (for example, a change in the preheating temperature caused by a fluctuation of the water content in the iron ore) if a reduction ratio is measured by taking a solid sample between the middle and last chambers of the reactor for the first stepwise reaction process, as described above. Properly regulating the operating conditions of the reactor for the first stepwise reaction process (a reaction temperature, a reaction pressure, a bed height of a fluidized bed and the like) corresponding to a correlation between the reduction ratio of the sample After the solid reaction and the reduction ratio obtained after the first stepwise reaction process, the reduction ratio obtained after the first stepwise reaction process can be changed. As a result, you can control the proportion of CH obtained after the second step reaction process. Also, the solid sample can be taken between the middle and last chambers of a reactor for the second stepwise reaction process instead of the solid sample at the reactor outlet for the first stepwise reaction process, and the parameter capable of changing the proportion of CH obtained after the second stage reaction process can be regulated, corresponding to the correlation between a CH ratio of the solid sample and the proportion of CH obtained after the second stage reaction process, thus adjusts the proportion of CH obtained after the second stepwise reaction process. In the case where the interior of a reactor for the second stage reaction process is divided into several chambers, a change in the conditions of an iron-containing feedstock can be detected early (for example, a change in temperature of preheating caused by a fluctuation of the water content in the iron ore) if a proportion of CH is measured by taking a solid sample between the middle and last chambers of the reactor for the second stepwise reaction process, as described above. Properly regulating the operating conditions for the reactor of the second stepwise reaction process (a reaction temperature, a reaction pressure, a bed height of a fluidized bed and the like) corresponding to a correlation between the CH proportion of the solid sample and the proportion of CH obtained after the second reaction process by stages, the proportion of CH obtained after the second stage reaction process can be controlled. In the chambers upstream to the middle chamber of the reactor (which are closer to a reactor inlet), the reaction does not progress uniformly. Therefore, a fluctuation of a composition of the solid sample taken is greater. For this reason, the front chambers to the middle chamber of the reactor are not suitable for the positions in which the solid sample is taken. As described above, it is preferable that the solid sample must be taken between the last and middle chambers of the reactor. Alternatively, the reduction ratio of the solid sample is not measured, but an exit gas composition is measured after mixing at the outlet of the reactor and is compared to an inlet gas composition. Therefore, a degree of progress in the reaction can be decided. Then, a sample of discharge gas can be taken for each chamber between the first and last chambers of the reactor for the first stepwise reaction process instead of the solid sample at the reactor outlet for the first stepwise reaction process, and a gas composition of the reactor can be regulated for the first stepwise reaction process corresponding to a correlation between the gas composition of the discharge gas and the reduction ratio obtained after the first stage reaction process, thus adjusting the proportion of CH obtained after the second stepwise reaction process. In the case where the interior of the reactor for the first stage reaction process is divided into many chambers, it is preferable that the gas composition of each chamber must be measured to perceive a change in the reaction of each chamber. As described above, a composition of a discharge gas from each chamber is measured in such a way that the degree of progress in the reaction of the solid can be estimated with high precision and the abnormalities in the reactor can be detected early. Therefore, the gas composition of the reactor for the first stage reaction process is appropriately regulated corresponding to a correlation between the composition of the discharge gas and the reduction ratio obtained after the first stage reaction process, thus changing the reduction ratio obtained after the first stage reaction process. As a consequence, the proportion of CH obtained after the second stepwise reaction process can be controlled. In addition, a sample of discharge gas can be taken for each chamber between the first and last chambers of a reactor for the second stepwise reaction process instead of the solid sample at the reactor outlet for the first stepwise reaction process , and a gas composition of the reactor can be regulated for the second stepwise reaction process corresponding to a correlation between the gas composition of the discharge gas and the proportion of CH obtained after the second stage reaction process, adjusting thus the proportion of CH obtained after the second stepwise reaction process. In the case where the interior of the reactor for the second stage reaction process is divided into many chambers, a gas composition of each chamber can be measured to estimate the degree of progress in the reaction of the solid with high precision and can be detect early abnormalities in the reactor, as described above. Therefore, the gas composition of the reactor for the second stage reaction process is suitably regulated corresponding to a correlation between the composition of the discharge gas and the proportion of CH obtained after the second stage reaction process.

Accordingly, the proportion of CH obtained after the second stepwise reaction process can be controlled. According to the present invention having the aforementioned constitution, by producing the carbide within the fluidized bed reactor, the two-step reaction process can be performed to carry out the further reduction and carburization reaction after the partial reaction of reduction after the partial reduction reaction, under the appropriate operating conditions. Therefore, the iron carbide product having an objective composition can be produced efficiently. Also, according to the present invention, in the case where the composition of the product leaves the range of the objective composition of the product, the appropriate operating conditions are selected corresponding to the state in the fluidized bed reactor in such a way that the operation of the Fluidized bed reactor can be easily handled. Furthermore, in the case where the present invention is applied to a rectangular mobile bed reactor (cross flow) as well as the fluidized bed reactor, the same effects can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a view showing an example of a schematic structure of an experimental apparatus for applying a method for producing iron carbide in accordance with the present invention; Figure 2 is a view showing a schematic structure of an apparatus for producing iron carbide to apply the method for producing iron carbide in accordance with the present invention; and Figure 3 is an enlarged view showing a gas sampling portion of a fluidized bed rector.

BEST WAY TO CARRY OUT THE INVENTION One embodiment of the present invention will be described below with reference to the drawings. 1) Experimental Apparatus An example of an experimental apparatus for applying a method for producing iron carbide in accordance with the present invention comprises the fluidized bed reactor 1 and the peripheral apparatus thereof as shown in Figure 1. The bed reactor fluidized 1 generally has a cylindrical shape and was provided with an electric heater 2 at the outlet thereof to set a predetermined temperature. A 50A tube (nominal size, external diameter of 60.5 mm) was used as a main part of the fluidized bed reactor 1. In addition, the temperature detecting sensors 3a, 3b, 3c, 3d, 3e and 3f were placed throughout of the length of the fluidized bed reactor 1 to 127 mm, 187 mm, 442 mm, 697 mm and 1707 mm from the bottom of the fluidized bed reactor 1, and in the dome of the fluidized bed 1, respectively in order to measure the temperature of the interior of the fluidized-bed reactor 1. The feeder tank 4 was connected to the upper portion of the fluidized-bed reactor 1 by line 7 by the antechamber of the feeder tank 6 having valves 5 provided on the front and rear. Consequently, a fine-sized feed (eg, an iron ore material comprising hematite (Fe203) as the main component) can be flowed from the feed tank 4 to the fluidized bed reactor 1 in a pressurized state. Additionally, the line 9 having the cooler 8 attached thereto, was connected to the bottom of the fluidized bed reactor 1 to cool and discharge the feed (raw material) into the fluidized bed reactor 1. The bottom of the bed reactor fluidized 1 was connected to the gas container 10 by lines 11 and 12 to allow a flow of a reaction gas having the predetermined gas composition in the gas container 10 inside the fluidized bed reactor 1. In addition, the saturator 13 between lines 11 and 12 to saturate the reaction gas with water. Lines 14, 15 and 16 were connected in series to the upper portion of the fluidized bed reactor 1 to direct a discharge gas obtained after the reaction to an incineration apparatus (not shown). further, a feed powder contained in the discharge gas was removed by a dust collector 17 provided between lines 14 and 15 and the filter 18 was installed on line 15. The discharge gas was cooled by the gas cooler 19 installed on line 15 to condense water. The condensed water can be separated by the drain separator 19a. 2) Experimental Conditions and Results An experiment to convert iron ore containing mainly hematite (Fe203) into iron carbide, that is, an experiment according to the present invention that is divided into partial reduction reaction and reduction and carburization reactions Further, it was carried out by carrying out a process to subject the iron ore to the first stepwise reaction process using a reduction gas comprising mainly hydrogen, and then carrying out a process to subject the iron ore to the second reaction process by stages using a gas mixture containing a reduction gas and a carburization gas comprising mainly hydrogen and methane. The iron ore had a composition of 97.3% by weight of Fe203, 1.4% by weight of FeO, and 1.3% by weight of Fe, and had a particle size of 1.0 mm or less. 3.52 kg of iron ore was supplied to the fluidized bed reactor 1. The interior of the fluidized bed reactor had a pressure of 3 to 4 kgf / cm2 G (G representing a pressure gauge), and had a temperature of 590 to 650 ° C. The feed compositions (iron ore as raw material) and the reaction gas are changed as set forth in Table 1 below. In Table 1 (outlet side - side) indicating the change in the composition of the reaction gas represents subtracting (a mean value at the inlet side of the fluidized bed reactor 1 during the period) from (a mean value in the output side of the fluidized bed reactor 1 during the period) §, which are measured by the online gas chromatography method. That is, output side = an average value on the outlet side of the fluidized bed reactor 1 during the period; input side = an average value on the inlet side of the fluidized bed reactor 1 during the period. In Table 1, an initial stage means the first stage reaction process, and middle and last stages mean the second stage reaction process.

TABLE 1 Initial stage Average stage Stage Last 0 0.5 hr 1.25 hr 2.25 hr 5.25 hr 6.25 hr Fe203 97.3 0.2 1.4 0.6 0.0 0.0 Fe304 0.0 59.2 18.8 13.3 5.8 5.1 e 0 o FeO 1.4 29.5 34.7 19.6 2.6 1.7 c o > o o Faith 1.3 11.1 45.1 22.6 0.0 0.0? o y e Fe3C 0.0 0.0 0.0 44.2 91.6 93.2 < _ > a, (Output side (Output side (Output side - Input side) - Input side) - Input side) 268 NmVhr you cu CH4 + 1 .8 - 0 .3 - 3 .1 -H O xa tí • H m • H U H2 - 9 .9 - 4 .3 + 2 .9 0 rH °? or 0 Ti or H20 - 9 .1 + 4 .3 + 3 .0 (Output side (Output side (Output side - Input side) - Input side) - Input side) 90 NmVhr m CH4 + 1. 1 - 4. 8 + 2 . 0 c or -H? ra -H tí H2 11. 5 - 1. 8 + 1 . 1 ü £ o or u H20 + 10. 9 + 6 7 + 3 . 1 u • you As clearly shown in Table 1, the feed is partially reduced in the first stage reaction process, and the further reduction and carburization is carried out in the second stage reaction process. It takes around 6.25 hours to get a conversion ratio of 93% or higher, which is convenient for an iron carbide process. More specifically, in the case where the feed (raw material) shown in Table 1 is subjected to the first stepwise reaction process using a reduction gas that mainly comprises hydrogen already to the second stepwise reaction process using a mixture of gas containing a reducing gas and a carburizing gas comprising mainly hydrogen and methane at a pressure of 3 to 4 kgf / cm2 G and a temperature of 590 to 650 ° C, it is predicted that an iron carbide product having a conversion ratio of 93.2% in iron carbide can be obtained when 6.25 hours pass after the reaction begins (which will hereafter be referred to as batch reaction data). In the case where the operating conditions such as a supply amount of the raw material, a composition of the raw material, a composition of a reaction gas, a flow rate of the reaction gas, a reaction pressure, a temperature of reaction and by the like are set at predetermined values in a specific fluidized-bed reactor, a residence time distribution in each chamber within the reactor has a constant value. By carrying out many experiments, it is possible to previously seize a transfer state under the predetermined operating conditions of a specific fluidized bed. The distribution of residence time means the following. Within the fluidized bed reactor having many chambers, the raw material in each chamber comprises a combination of several different residence times in the reactor. The combination becomes constant if the operating conditions are determined. For example, if 25% of the raw material in some chamber has a residence time in the reactor of 1 to 1.5 hours, 50% of the raw material has a residence time in the reactor of 1.5 to 2 hours and 25 % of the raw material has a residence time in the reactor of 2 to 2.5 hours, this combination is referred to as the residence time distribution. Accordingly, if the batch reaction data mentioned above is obtained by running experiments previously for various types of iron ore materials, it is possible to predict a composition of an output side product when an iron ore material is loaded. it has a certain composition within the fluidized bed reactor that has a transfer state known as a sum of the product of the residence time distribution and the data of the batch reaction within the specific fluidized bed reactor. Selecting the operating conditions of the first step reaction process and the second step reaction process such that a predicted product composition of the output side is maintained, within the range of an objective composition of the product, it is possible to obtain an iron carbide product having an objective quality. When the target quality interval has to be changed or the target quality of the same interval has left, it is possible to control the quality by correcting the operating conditions (the amount of supply of the raw material, the composition of the raw material, the composition of the reaction, the flow rate of the reaction gas, the reaction pressure, the reaction temperature and the like). Taking into consideration that an established value which can be detected in a sufficiently short time for a response time under the operating conditions, and that has a great gain for the correction and a high astringency, is effective in the control of the quality under the operating conditions, the present inventors have found a method. An example of the method will be described below. As a method for measuring a reduction ratio of a solid sample, a method for estimating the reduction ratio by measuring a magnetic permeability is preferable, because it can be performed conveniently and quickly. More specifically, if a relationship between the composition and the magnetic permeability of an iron carbide product is obtained in advance, effective countermeasures can be taken using a ratio such as a test curve. For example, the magnetic permeability of the solid sample at an output of a reactor is measured for the first stepwise reaction process or from a middle position at the reactor outlet for the first stepwise reaction process (in order to control a degree of the partial reduction of the output side product at the reactor outlet for the first stepwise reaction process), or the magnetic permeability of the solid sample at a reactor outlet of the second stage reaction process is measured or from a middle position at the exit of the reactor for the second stepwise reaction process (in order to control the quality (CH ratio) of the product obtained after the second stepwise reaction process). If the magnetic permeability leaves a preferred range in the test curve, the composition of the reaction gas or the reaction temperature is changed in the following manner. Accordingly, it is possible to obtain an iron carbide product having an objective composition. By adding methane to the reduction gas in the first stepwise reaction process, a proportion of hydrogen composition can be changed. As a consequence, it is possible to control the reaction time required to obtain the reduction ratio in the first step reaction process and a predetermined reduction ratio.

By adding hydrogen or methane to the reducing gas and the carburizing gas in the second stepwise reaction process, a ratio of the composition of hydrogen to methane can be changed. Therefore, it is possible to control the reaction time required to obtain a carburization ratio (iron carbide conversion ratio) in the second step reaction process and a predetermined carburization ratio. In this case, if a sample is obtained in the middle position of the reactor in each reaction process, a variation in the magnetic permeability is great and a state of operation can clearly be reached. By detecting the quality of the reactor output early, one can expect the effects of quality control to increase. Moreover, it is possible to control the carburization ratio of a final product, and the shape and amount of the residual iron oxide by carrying out the reaction processes mentioned above. It is preferable that the reaction temperature in the first step reaction process should be set at 550 to 750 ° C. If the reaction temperature is lower than 550 ° C, the reaction rate is lower and the reaction time increases. If the reaction temperature is higher than 750 ° C, there is a problem with a structure that can resist the heat of the reactor. There is a possibility that the hematite reduction reaction could cause sintering within the range of about 600 ° C to about 700 ° C and reaction time could be increased. For this reason, the reaction has been carried out conventionally at a temperature of about 590 ° C, which is lower than the previous temperature range. According to the present invention, the reduction reaction is divided into two stages, and the reduction ratio in the first stepwise reaction process is not greatly increased. Therefore, even if the reaction temperature is increased, sintering is not caused and the reaction rate does not decrease. The second stage reaction process performs the reduction and additional carburization at the same time. The sintering is caused with greater difficulty than in the case where only the reduction is carried out. Therefore, it is preferable that the reaction temperature should be set a little higher, ie, at around 610 to 750 ° C in order to shorten the time of the reaction process. Sometimes it is desirable that portions other than iron carbide in the iron carbide product should comprise Fe304, which is more stable. In this case, the reaction can be carried out by setting a temperature of about 575 ° C or less where a slightly unstable FeO is not present, for example, by setting the temperature of the second stepwise reaction process at about 550 to 570 ° C, and the residual iron may only contain Fe304. As expressed by the general reaction formula, it is assumed that an amount of H20 in the reaction gas is increased if the reduction reaction and the carburization reaction progress. If a change in the amount of H20 in the reaction gas is known, a degree of the progress of the reaction can be detected. If the amount of H20 in the reaction gas is measured by the on-line gas chromatography method, for example, several actions can be taken to detect the degree of progress in the reaction by a value of H20 to monitor the progress of the reaction. reaction. In some cases, the reaction proceeds more rapidly or slowly than in Table 1 depending on the type of iron ore as set forth in Table 2 below. In Table 2, the reaction progresses rapidly ^ means the case where a composition obtained after 1.25 hours in Table 1 was set at an initial value and a reaction of 2 hours was completed in 1 hour, and if the reaction progresses slowly - ^ means the case where the composition obtained after 1.25 hours in Table 1 was set at an initial value and the 0.5 hour reaction required 1 hour.

TABLE 2 The reaction progresses The reaction progresses rapidly slowly Early stage of the early stage reaction reaction Fe203 01.4 - > 00.0 01.4 - > 01.0. cti Fe304 18.8 - > 10.3 18.8 - > 14.9 Or 0 a? FeO 34.7 - > 10.6 34.7 - > 26.3 or rtí 0 u 0? Faith 45.1 - > 00.0 45.1 - > 35.7 a e u 0 o e Fe3C 00.0 - > 79.1 00.0 - > 22.1 Side of Side of Side of exit - entrance Exit - entrance 268 NmVhr ¡3 tí CH4 4.8 3.6 vO in cd? H2 0.3 0.2 a e 0 O < ¡) H20 + 5.0 + 3.8 or i 90 NmVhr Side of Side of Side of exit - entrance exit - entiada to CH4 8.1 - 4.9 o? - or H2 to + 0.6 + 0.2 or ¡? 0 H20 + 9.1 + 5.1 or a > d Table 2 can also be used to detect the degree of progress in the reaction in the same manner as Table 1. 3) Summary of the Production Apparatus Figure 2 is a view showing a schematic structure of an iron carbide producing apparatus for applying the method for producing iron carbide in accordance with the present invention. The production apparatus comprises the portion 20 of the first stepwise reaction process for performing the partial reduction of an iron-containing material for manufacturing, and a portion 40 of the second stepwise reaction process for performing the reduction and additional carburization reaction. . Portion 20 of the first step reaction process includes lines 21 and 22, compressor 23, line 24, heat exchanger 25, line 26, heater 27, line 28, fluidized bed reactor 28, line 30, heat exchanger 25, line 31, gas cleaner 32 and line 33 which form a cycle. A reaction gas is supplied to a lower gas inlet of the fluidized bed reactor 29 through line 22, compressor 23, line 24, heat exchanger 25, line 26, heater 27, and line 28, and flows from an upper gas outlet of fluidized bed reactor 29 to line 30, heat exchanger 25, line 31, gas cleaner 32, line 33, line 21 and line 22 in order . In this way, a cycle is formed to cause a first reaction gas to circulate. Although the pressure drops while the gas circulates in each device, the pressure is appropriately elevated by the compressor 23 such that the reaction gas can circulate in the cycle. The reaction gas flowing inside the fluidized bed reactor 29 exchanges heat with a reacted gas flowing out of the reactor 29 through the heat exchanger 25, and is further heated by the heater 27 at a suitable reaction temperature. The gas cleaner 32 comprises the hollow body 34, the line 35 for injecting water into the gas, and the line 36 for discharging the water in the body 34, and serves to cool the gas flowing out of the reactor 29, and condenses and remove the current in the gas. Moreover, a gas having predetermined composition is supplied to a circulation path through the line 37 connected to a portion where the lines 21 and 22 are coupled to each other. In addition, a predetermined composition of the gas can be discharged from the circulation path by the line 38 connected to a portion where the lines 33 and 21 are coupled together. By regulating the amount of the gas supplied and the discharge gas, the composition of the reaction gas flowing in the reactor 29 and a change in the gas composition are set and it can be prevented that a decrease in the reaction rate is caused by the reaction. A flow of the reaction gas in the portion 40 of the second stepwise reaction process is also the same as in the portion 20 of the first step reaction process. Therefore, common portions are indicated in reference numbers having 20 attached to the reference numbers of the portion 20 of the first step reaction process, and the description will be omitted. A flow of the feed (raw material) into the reactors is as follows: the fine-sized iron ore is stably supplied in an upper portion of the fluidized-bed reactor 29 of the portion 20 of the first step-wise reaction process in there through line 60. The fine-sized iron ore which has been completely subjected to the partial reduction reaction is continuously supplied from a lower portion of the fluidized bed reactor 29 to the fluidized bed reactor 49 of the portion 40 of the second stepwise reaction process through line 61. The reduction reaction and the further carburization reaction are carried out in the fluidized bed reactor 49, and the converted iron carbide is discharged continuously through line 62. It is sufficient that only the reduction reaction be taken into consideration for the first step reaction process as the composition of the reaction gas used in each process. Therefore, the first step reaction process is carried out using the reaction gas containing mainly hydrogen. For this reason, a concentration of hydrogen and a reaction rate of the reduction reaction can be increased, and the reaction time can be shortened more than in the state of the art. Because the reduction reaction and the carburization reaction must be taken into consideration for the second step reaction process, a gas mixture containing hydrogen and methane is used. However, the reduction reaction progresses partially in the first stepwise reaction process. Therefore, importance can be attached to the carburization reaction. Accordingly, a methane concentration can be raised to increase the speed of the carburization reaction and to shorten the reaction time. A constant amount of methane can be added to the reduction gas comprising mainly hydrogen in the first stepwise reaction process to lower the concentration of hydrogen and to control the rate of the reduction reaction. By regulating the methane concentration of the reaction gas in the second stepwise reaction process, the speed of the carburization reaction can be controlled, the deposition of the free carbon can be decreased and the reaction time can be controlled to obtain a of predetermined carburization. Figure 3 is an enlarged view showing a gas sampling portion of a fluidized bed reactor. In Figure 3, the suction portion 71 is fixed in a lower position than the upper part 74 of the partition wall 73 of the fluidized bed reactor diagonally with respect to the side wall 72 of the fluidized bed reactor. It is preferable that a gradient (angle?) Of the suction pipe 75 for insertion into the suction portion 71 must be sufficiently greater than an angle of repose of the feed (raw material). It is preferable that not much air should be extracted and that a flow rate should be set without fine particles having a size of 10 μ or more.

Preferably, a distance L between the valve 76 attached to the suction pipe 75 and the suction portion 71 increases comparatively and a temperature of the valve 76 is decreased by heat radiation between them. The filter 78 made of glass wool is attached to the interior of the dust separator 77 installed on a rear face of the valve 76, thereby removing a powder. The valve 79 is fixed to a lower part of the dust separator 77, and a dust container 80 is provided. It is preferable that the gas must be discharged in an amount of approximately 100 milliliters / seconds from the valve 81 installed in a part upper of the dust separator 77. In order to prevent the generation of drainage, it is preferable that the dust separator 77, other accessory valves and the like should be placed in a thermostatic box. Using a gas sampling apparatus having the structure mentioned above, a sample of discharge gas is taken for each chamber from the inlet to the last outlet chamber in the reactor for the first stepwise reaction process (in order to control the degree of partial reduction of the product from the outlet side to the exit of the reactor for the first stage reaction process), or a sample of the discharge gas is taken for each chamber from the entrance of the last chamber to the exit of the reactor for the second stepwise reaction process (in order to control the quality (CH ratio) of the product obtained after the second stepwise reaction process) to measure those gas compositions by the gas chromatography method or the like. If the gas composition leaves the preferable range, the quality (CH ratio) of the product can be controlled by changing the gas compositions in the first step reaction process and the second step reaction process as described above.

INDUSTRIAL APPLICABILITY Because the present invention has the aforementioned constitution, the present invention is suitable for an apparatus for obtaining an iron carbide product having a target composition in a two-step reaction process.

Claims (5)

1. A method for managing an operation of a process for producing iron carbide, comprising the steps of: performing a first stage reaction process to partially reduce several iron-containing materials for the manufacture of iron, and then performing a second process of step reaction to carry out the reduction and further carburization; taking a solid sample at the outlet of a reactor for the first stepwise reaction process to measure a reduction ratio of the solid sample; and regulating a parameter capable of changing the reduction ratio of the first stepwise reaction process to adjust a proportion of iron carbide obtained after the second stage reaction process.

2. The method for handling an operation of a process for producing iron carbide according to claim 1, wherein the solid sample is taken between the middle and last chambers of the reactor for the first stepwise reaction process instead of the solid sample at the reactor outlet for the first stage reaction process; and the parameter capable of changing the reduction ratio of the first stage reaction process is regulated, corresponding to the correlation between the reduction ratio of the solid sample and the reduction ratio obtained after the first stage reaction process; thus adjusting the proportion of iron carbide obtained after the second stage reaction process.

3. The method for handling an operation of a process for producing iron carbide according to claim 1, wherein the solid sample is taken between the middle and last chambers of a reactor for the second stepwise reaction process instead of the solid sample at the reactor outlet for the first stepwise reaction process; and the parameter capable of changing the proportion of iron carbide obtained after the second stage reaction process is regulated, corresponding to a correlation between a ratio of iron carbide of the solid sample and the proportion of iron carbide obtained after the second process of reaction by stages; whereby the proportion of iron carbide obtained after the second stage reaction process is adjusted.

4. The method for handling an operation of a process for producing iron carbide according to claim 1, wherein a sample of discharge gas is taken for each chamber between the first and last chambers of the reactor for the first reaction process step by step instead of the solid sample at the exit of the reactor for the first stepwise reaction process; and a gas composition of the reactor is regulated for the first stepwise reaction process, corresponding to a correlation between the gas composition of the discharge gas and the reduction ratio obtained after the first stage reaction process; so the proportion of iron carbide obtained after the second stage reaction process is adjusted.

5. The method for handling an operation of a process for producing iron carbide according to claim 1, wherein a sample of discharge gas is taken for each chamber between the first and last chambers of a reactor for the second process of step reaction in place of the solid sample at the exit of the reactor for the first step reaction process; and a gas composition of the reactor is regulated for the second stepwise reaction process corresponding to a correlation between the gas composition of the discharge gas and the proportion of iron carbide obtained after the second stage reaction process; so the iron carbide obtained after the second stepwise reaction process is adjusted.