TWI568855B - Compounded slag controlling method of producing carbothermic reaction of iron at tall pellets bed - Google Patents

Description

Slag control method for producing high-layer carbon-thermal reduced iron

The present invention relates to a slag-containing slag control method, and more particularly to a slag-containing slag control method for producing a high-layer carbon-based reduced iron.

The traditional blast furnace iron making method is to add sinter, coke and flux into the blast furnace, and the reduction reaction is carried out by hot air and pulverized coal injection. The process must first prepare the sinter and coke. Sinter ore is a block-shaped raw material that is sintered from fine-grained iron ore raw materials into a suitable physicochemical property through a sintering process, and coke is produced by metallurgical coal through a coking process. The raw materials required for the two processes are iron ore and metallurgical coal of higher grade, which are generally called raw materials for blast furnace. Due to the vigorous development of the steel industry in recent years, the use of blast furnace materials is large, and the production is increasingly short, making the price high. In addition, with the development of ironmaking technology in the 21st century towards environmental protection, energy conservation and waste recycling, the coking and sintering processes are seriously polluted, making the steel industry constantly seeking new ways to eliminate the coking and sintering process.

Therefore, it is necessary to provide a slag control method for producing high-layer carbon-thermal reduced iron to solve the problems of the conventional technology.

The main object of the present invention is to provide a slag control method for producing high-layer carbon-carbo-reduced iron, which is obtained by mixing iron-containing composition, coal carbon and a binder into a mixture, and then forming the mixture into a plurality of pellets. Stacking into a multi-layer pellet stack, then reducing the iron component of the iron-containing composition in the multilayer pellet stack to iron by means of carbothermal reduction, and allowing the high-layer layer of the multilayer pellet stack (ie, the multilayer sphere) The uppermost layer of the cluster has a high metallization rate of over 80%, which is not required to be known. The coking and sintering process can obtain the reduced iron, thereby reducing the manufacturing cost and moving toward environmental protection and energy saving.

A secondary object of the present invention is to provide a slag-controlling method for producing high-layer carbothermic reduced iron, which utilizes a ferrous composition having a specific composition to maintain a substantially complete spherical shape after the carbothermal reduction of the pellets. And the pellet has a good shrinkage rate and a high overall metallization rate and an upper metallization rate.

In order to achieve the above object, the present invention provides a slag controlling method for producing a high-layer carbothermic reduced iron, comprising the steps of: providing an iron-containing composition comprising 0.2 to 11.5 parts by weight of SiO ₂ , 0.2 to 16.2 parts by weight of Al ₂ O ₃ and 72.3 to 85.4 parts by weight of FeO or Fe ₂ O ₃ , wherein the weight ratio of SiO ₂ to Al ₂ O ₃ of the iron-containing composition ranges from 0.71 to 7; a mixing step of adding coal and 0.1 to 1 part by weight of a binder to the iron-containing composition to form a mixture in which the molar amount of carbon contained in the coal is in FeO or Fe ₂ O ₃ The ratio of the molar number of oxygen contained is in the range of from 1.0 to 1.1; the mixture is subjected to a pellet forming step to form the mixture into a plurality of pellets, wherein the diameter of each of the pellets The range is from 5 mm to 30 mm; a pellet stacking step is performed, the pellets are stacked on each other to form a multilayer pellet stack; and the multilayer pellet stack is subjected to a carbothermal reduction step, wherein the carbon The heating temperature of the thermal reduction step ranges from 1400 ° C to 1550 ° C, and The thermal time ranges from 50 to 70 minutes such that the overall metallization rate of the multilayer pellet stack ranges from 74.8% to 89.8% and the metallization of the uppermost pellets in the multilayer pellet stack Rates range from 82.9% to 87.3%.

In an embodiment of the invention, the iron-containing composition further comprises 0.1 to 1.0 part by weight of CaO and 0.1 to 1.0 part by weight of MgO.

In an embodiment of the invention, the iron-containing composition comprises iron concentrate, hematite, magnetite or limonite.

In one embodiment of the present invention, wherein the step of adjusting further comprises a step of providing the iron-containing composition, the addition of purified through or pure Al ₂ O ₃ to SiO ₂ of the iron-containing composition of SiO ₂ and the Al ₂ The range of the weight ratio of O ₃ is adjusted to be between 0.71 and 7.

In an embodiment of the invention, the weight ratio of SiO ₂ to Al ₂ O ₃ of the iron-containing composition ranges from 0.71 to 1.65.

In an embodiment of the invention, the weight ratio of SiO ₂ to Al ₂ O ₃ of the iron-containing composition ranges from 1.97 to 7.

In an embodiment of the invention, the binder is bentonite.

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Fig. 1 is a flow chart showing a method for controlling a slag containing high-layer carbon-thermal reduced iron according to an embodiment of the present invention.

The above and other objects, features and advantages of the present invention will become more <RTIgt; Furthermore, the directional terms mentioned in the present invention, such as upper, lower, top, bottom, front, rear, left, right, inner, outer, side, surrounding, central, horizontal, horizontal, vertical, longitudinal, axial, The radial, uppermost or lowermost layers, and the like, are merely illustrative and understanding of the invention and are not intended to limit the invention.

Referring to FIG. 1, FIG. 1 is a schematic flow chart showing a method 10 for controlling a slag containing high-layer carbon-thermal reduced iron according to an embodiment of the present invention. The slag control method 10 for producing high-layer carbothermic reduced iron according to an embodiment of the present invention mainly comprises the following steps 11 to 15: providing an iron-containing composition comprising 0.2 to 11.5 parts by weight of SiO ₂ , 0.2 to 16.2 parts by weight of Al ₂ O ₃ and 72.3 to 85.4 parts by weight of FeO or Fe ₂ O ₃ , wherein the weight ratio of SiO ₂ to Al ₂ O ₃ of the iron-containing composition (hereinafter referred to as S/A) Is from 0.71 to 7 (step 11); performing a mixing step of adding coal and 0.1 to 1 part by weight of a binder to the iron-containing composition to form a mixture in which carbon contained in the coal The ratio of the molar number to the molar number of oxygen contained in FeO or Fe ₂ O ₃ ranges from 1.0 to 1.1 (step 12); the mixture is subjected to a pellet formation step to form the mixture into a plurality of a pellet, wherein each of the pellets has a diameter ranging from 5 mm to 30 mm (step 13); performing a pellet stacking step of stacking the pellets to each other to form a multilayer pellet stack (Step 14); and performing a carbon thermal reduction step on the multilayer pellet stack, wherein the heating temperature of the carbon thermal reduction step The range is from 1400 ° C to 1550 ° C, and the heating time ranges from 50 to 70 minutes, so that the overall metallization ratio of the multilayer pellet stack ranges from 74.8% to 89.8% and the multilayer pellet stacking The metallization rate of the uppermost pellet in the body ranges from 82.9% to 87.3% (step 15).

Referring to FIG. 1 , a method for controlling slag forming high-layer carbon-thermal reduced iron according to an embodiment of the present invention is first performed in step 11 : providing an iron-containing composition comprising 0.2 to 11.5 by weight. Parts SiO ₂ , 0.2 to 16.2 parts by weight of Al ₂ O ₃ and 72.3 to 85.4 parts by weight of FeO or Fe ₂ O ₃ (ie, the total combined parts by weight of FeO and/or Fe ₂ O ₃ is 72.3 to 85.4 parts by weight) Wherein the weight ratio of SiO ₂ to Al ₂ O ₃ of the iron-containing composition ranges from 0.71 to 7. In this step, the iron-containing composition may be derived from a single iron ore or multiple iron ore, such as iron concentrate, hematite, magnetite or limonite. In other words, because the composition ratio of various iron ore is not the same, or the iron ore is based on the company/origin (such as Australian iron ore company Atlas, Western Australia iron ore Citic, Zhonghong company, Luobohe iron ore company ROBE RIVER, Brazilian fresh water The different proportions of the different components produced by the river iron ore company CVRD, the western Australian mine Karara, and the Canadian iron ore company Alderon can make the composition of the iron-containing composition fall above by matching the proportions of various iron ore. Among the ingredients. Therefore, the slag control method for producing high-layer carbon-thermal reduced iron of the present invention can be flexibly used in accordance with the existing iron ore.

In one embodiment, the iron-containing composition may be composed of low grade or high grade iron ore, which contains, in addition to a specific ratio of SiO ₂ , Al ₂ O ₃ and FeO or Fe ₂ O _{3 .} In addition, it may contain CaO, MgO, and other unavoidable components or impurities, which are components derived from iron ore sources. In an exemplary embodiment, the iron-containing composition contains 0.1 to 1.0 part by weight of CaO and 0.1 to 1.0 part by weight of MgO.

In one embodiment, if the existing iron ore cannot be combined with the weight ratio of SiO ₂ to Al ₂ O ₃ of the iron-containing composition from 0.71 to 7, an adjustment step can be performed by adding pure Al _{2 .} O ₃ or pure SiO _{2 is} used to adjust the range of the weight ratio of SiO ₂ to Al ₂ O ₃ of the iron-containing composition to be between 0.71 and 7. It is worth mentioning that if the weight ratio is less than 0.71 or greater than 7, the pellets which are disadvantageous for the subsequent carbothermal reduction step remain substantially intact. In another embodiment, the weight ratio of SiO ₂ to Al ₂ O ₃ of the iron-containing composition ranges from 0.71 to 1.65. In still another embodiment, the weight ratio of SiO ₂ to Al ₂ O ₃ of the iron-containing composition ranges from 1.97 to 7.

The slag control method for producing high-layer carbothermic reduced iron according to an embodiment of the present invention is followed by step 12: performing a mixing step of adding coal and 0.1 to 1 part by weight of a binder to the ferrous composition, To form a mixture in which the ratio of the number of moles of carbon contained in the coal to the number of moles of oxygen contained in FeO or Fe ₂ O ₃ ranges from 1.0 to 1.1. In one embodiment, the binder is bentonite. In yet another embodiment, the coal may be from North Korean anthracite or Rio Tinto. In another embodiment, the ratio of the number of moles of carbon contained in the coal to the number of moles of oxygen contained in FeO or Fe ₂ O ₃ may be equal to or slightly greater than 1.0 because In the carbothermal reduction reaction of iron, the theoretical molar number is measured by reacting one mole of carbon with one mole of oxygen to reduce iron. Therefore, the range of the ratio of the number of moles of carbon contained in the coal to the number of moles of oxygen contained in FeO or Fe ₂ O ₃ is controlled to be between 1.0 and 1.1, or equal to or slightly greater than 1.0. It can reduce the amount of coal used to reduce manufacturing costs.

A slag control method for producing high-layer carbothermic reduced iron according to an embodiment of the present invention is followed by a step 13 of performing a pellet formation step on the mixture to form a plurality of pellets, wherein the pellets Each of the diameters ranges from 5 mm to 30 mm. In this step 13, the ball can be formed into a ball shape by a machine, or can be manually formed into a ball shape by a human hand.

The slag control method 10 for producing high-layer carbothermic reduced iron according to an embodiment of the present invention is followed by step 14 of performing a pellet stacking step of stacking the pellets to each other to form a multilayer pellet stack. In this step, it is mainly to conform to the stacking configuration performed by the heating zone of a commercially available heating device. Generally used on the market When the heating device performs the carbothermal reduction step, the heating device usually has a bell-shaped heating space, and the shape of the multi-layer pellet stack can be formed correspondingly according to the bell-shaped heating space. The heat source of the heating device is usually located above the bell jar type heating space, and the bell jar type heating space can pass around the side wall through the heat insulating wall to prevent heat energy from being dissipated. In general, since the uppermost pellet is closest to the heat source and has a better metallization rate, the upper metallization rate is higher than the overall metallization rate, but the overall metallization rate may be higher than the upper metallization rate. opportunity.

The slag control method for producing high-layer carbothermic reduced iron according to an embodiment of the present invention is finally provided in step 15: performing a one-carbon thermal reduction step on the multilayer pellet stack, wherein the range of heating temperatures of the carbon thermal reduction step It is from 1400 ° C to 1550 ° C, and the heating time ranges from 50 to 70 minutes, so that the overall metallization ratio of the multilayer pellet stack ranges from 74.8% to 89.8% and the multilayer pellet stack The metallization rate of the uppermost pellet in the range is from 82.9% to 87.3%.

It is to be noted that the slag-controlling method for producing high-layer carbothermic reduced iron according to an embodiment of the present invention is at least selected by selecting the iron-containing composition having a specific composition so that the pellet after the carbothermal reduction step is carried out. The substantially complete spherical shape is maintained, and the pellets have a good shrinkage ratio and a high overall metallization ratio and an upper metallization ratio.

It is to be noted that the slag-controlling method for producing high-layer carbothermic reduced iron according to the embodiment of the present invention is at least a specific weight ratio of the weight ratio of SiO ₂ to Al ₂ O ₃ of the iron-containing composition. In the range, the pellets after the carbothermal reduction step are maintained in a substantially intact spherical shape, and the pellets have a good shrinkage ratio and a high overall metallization ratio and an upper metallization ratio.

It is to be noted that the iron-containing composition having a specific composition selected in the present invention, when subjected to the carbothermal reduction step, the original composition of the iron-containing composition may be changed to a new one due to the carbothermal reduction step. Composition, the liquid phase temperature of the new composition can be observed from the phase diagram to be at a higher liquidus temperature. For example, when the S/A is 1.65, the eutectic of Al ₆ Si ₂ O ₁₃ is generated in the new composition. The liquefaction temperature is 1850 ° C; when S / A is 0.71-1.04, a eutectic of FeAl ₂ O ₄ is produced in the new composition, and the liquefaction temperature is 1780 ° C. These eutectics (also referred to as slag phases) with a high liquefaction temperature help the pellets to maintain a substantially intact sphere after the carbothermal reduction step. In other words, the iron-containing composition having a specific composition selected in the present invention is subjected to a reaction mixture by various experimental instruments such as a scanning electron microscope and an energy dispersive X-ray spectroscopy apparatus (hereinafter referred to as SEM/EDS). Qualitative measurement and observation were carried out, and the slag phase region was verified by a ternary phase diagram of FeO _n -SiO ₂ -Al ₂ O ₃ (where FeO _n refers to FeO and/or Fe ₂ O ₃ ). It can be seen that the present invention has taken into consideration the high liquid phase temperature of the new composition which is generated when the carbothermal reduction step is carried out, and then reverses the original composition to obtain the specific composition of the iron-containing composition to be selected and the obtained composition thereof. The pellets have the advantages of good shrinkage and high overall metallization and upper metallization.

The following are a number of comparative examples and examples to demonstrate that the slag control method for producing high-layer carbothermally reduced iron in the embodiment of the present invention can indeed make the pellets subjected to the carbothermal reduction step have a good shrinkage rate and a high overall The advantages of metallization rate and upper metallization rate.

First, the first set of experimental examples A1-A4 and comparative examples A5-A9 were based on the use of a single iron ore (Western iron ore Citic) with pure SiO ₂ and/or Al ₂ O ₃ agents, North Korean anthracite and soap. Soil (adhesive), the weight of which is shown in Table 1 below, wherein the molar number of carbon contained in the North Korean anthracite coal and the oxygen contained in FeO or Fe ₂ O ₃ in the Western Australian iron ore Citic The ratio of the number is 1. All of the above compounds, iron ore, coal and binder are uniformly mixed to obtain a mixture which is kneaded into a pellet. Further, based on SiO ₂ and Al ₂ O ₃ and the weight ratio of iron contained in and added together with the pure SiO ₂ and / or Al ₂ O ₃ and SiO ₂ calculated agents Al ₂ contained in the mixture The weight percentage of O ₃ is shown in Table 1 below. Thereafter, the pellet was placed in a heating device, and a carbothermal reduction reaction was carried out at 1400 ° C for 60 minutes. It should be mentioned that the main components described in the following Table 1 are FeO or Fe ₂ O ₃ (ie FeO _n ) contained in iron ore, SiO 2 and Al ₂ O ₃ , and pure SiO ₂ added thereto. / or Al ₂ O ₃ agent is counted, and the total amount of the three compounds FeO _n , SiO ₂ and Al ₂ O ₃ is taken as 100% by weight, and the weight percentage of each compound is calculated separately.

Examples A1 to A4 and Comparative Examples A5 to A9 were analyzed by the following analytical methods after carrying out the carbothermal reduction reaction.

First, the degree of integrity of the pellet is observed with the naked eye, and it is judged as A when the substantially complete spherical shape is maintained, but it is judged as B when there is still a part of the solid matter, and C when only the powder is left. Please refer to Table 2 below for the results. Thereafter, the metallization rate and the residual carbon ratio of the pellets were analyzed by wet chemical analysis; and the diameter of the pellets before and after the reaction was measured and the volume of the pellets was converted to calculate the shrinkage ratio before and after the reaction (by the volume before the reaction) As 100%), the results are shown in Table 2 below.

As can be seen from the analysis in Table 2 above, when the S/A is in the range of 0.71 to 1.65, good pellet integrity, metallization ratio, residual carbon ratio and shrinkage ratio can be obtained. However, when S/A was in the range of 8-40.1 (Comparative Example A5-A8), not only good pellet integrity was not obtained, but also the metallization ratio was lower than that of Examples (A1-A4). Further, Examples A1 to A4 had stable residual carbon ratios, and the residual carbon ratios of Comparative Examples A5 to A9 were excessively widened, which was disadvantageous for industrial applications. It is worth mentioning that although Comparative Example A9 has a substantially complete spherical shape, substantially the metallization ratio of Comparative Example A9 is too low, and the residual carbon ratio is too high, which is disadvantageous for industrial applications.

Further, the above Examples A1 to A4 and Comparative Examples A5 to A9 were analyzed by SEM/EDS. In Comparative Example A6-A8, a eutectic containing Fe ₂ SiO ₄ (low liquefaction temperature, 1205 ° C), according to a ternary phase diagram of FeO _n -SiO ₂ -Al ₂ O ₃ (not shown), its liquid phase The area is wider, so the surface area of the gas-solid reduction reaction in the pellet is reduced, which not only reduces the reduction rate, but also causes the pellet to collapse easily. On the other hand, in Comparative Example A9, since SiO ₂ was contained, the liquidus temperature was high and the liquid phase region was narrow, so that Comparative Example A9 could be kept in a relatively complete spherical shape. Further, in Example A1, a eutectic of Al ₆ Si ₂ O ₁₃ was contained (liquidus temperature was high, 1850 ° C); and in Examples A2 to A4, a eutectic of FeAl ₂ O ₄ was contained (the liquidus temperature was high, 1780 ° C). Since the liquidus temperatures of the two eutectics are high, the pellets can maintain a complete spherical shape and have a narrow liquid phase, which contributes to the gas-solid reduction reaction in the pellets. It can be seen that when the S/A is controlled within a certain range (for example, 0.71-1.65), the composition inside the pellet can be moved from the initial component to the high-temperature liquid region, so that the interior is not easily liquefied or partially in the carbothermal reduction reaction. Slag. Under the barrier of no liquid slag, it is easier to carry out the complete gas-solid reduction reaction, so that the iron phase in the pellet is formed earlier, and then there is a chance to carry out the sintering reaction to become a continuous metal phase, so the pellet strength is sufficient and it is not easy to collapse.

Continuing, a second set of embodiments is carried out which, according to the results of the first set of examples, adjusts the composition of Al ₂ O ₃ in the pellet by single or multiple iron ore furnishing, so in the second The experimental examples of the group do not additionally contain pure SiO ₂ and/or Al ₂ O ₃ agents. The iron ore batch and coal mine ingredients used in the examples in the second group are shown in Table 3 below, wherein the molar number of carbon contained in the coal carbon source and the molar number of oxygen contained in FeO or Fe ₂ O ₃ The ratio of the ratio is 1.1. After the iron ore batch and coal mine ingredients are prepared, add an appropriate amount of binder (for example, 100 parts by weight of the main component of the iron ore compound, 0.1 to 1 part by weight of the binder may be added) and uniformly mixed to obtain a Mix and pour into multiple pellets. Thereafter, the pellets were stacked on each other to form a multilayer pellet stack, and placed in a heating zone of a heating device, and a carbothermal reduction reaction was carried out at 1500 ° C for 60 minutes.

It is worth mentioning that in Table 3 above, the total weight percentage of iron ore source and coal carbon source is calculated separately. In other words, for example, in example B1, the source of iron ore is 100% from the iron of Zhonghong Company. Mine, coal source is 100% from the carbon of RioTinto. The main components in the second group of examples refer to FeO or Fe ₂ O ₃ (ie, FeO _n ), SiO ₂ and Al ₂ O ₃ contained in iron ore, and the total amount of the three compounds is regarded as 100% by weight. Thereafter, the weight percentage of each compound was calculated separately.

Examples B1 to B5 after the carbothermal reaction, similar to the first The analysis was carried out in the manner of the group examples, and the analysis results are shown in Table 4 below. It is worth mentioning that, since in the embodiments B1 to B5, the multilayer pellet stack, there will be a difference between the upper layer and the whole in the metallization rate and the shrinkage ratio, wherein the upper layer refers to the most in the multilayer sphere stack. The analysis of the upper pellets, as a whole, refers to the analysis of the entire multilayer sphere stack.

As can be seen from the above Table 4, in addition to having good pellet integrity, Examples B1 to B5 have an upper metallization ratio of 80% or more, and an average metallization ratio of 80% or more. On the other hand, the upper layer shrinkage ratio and the overall shrinkage ratio can further verify the correctness of the upper metallization ratio and the overall metallization ratio.

In summary, the slag control method for producing high-layer carbon-carbo-reduced iron of the present invention is to mix iron-containing composition, coal carbon and binder into a mixture, and then form the mixture into a plurality of pellets and stack them into a mixture. a multi-layer pellet stack, which is then reduced by carbon to the iron component of the iron-containing composition in the multilayer pellet stack, and the high-layer layer of the multilayer pellet stack (ie, the multilayer pellets stacked) The uppermost layer of the body has a high metallization rate of 80% or more, and it is not necessary to undergo a conventional coking and sintering process to obtain reduced iron, thereby reducing manufacturing costs and moving toward environmental protection and energy saving. In addition, the slag control method for producing high-layer carbon-thermal reduced iron of the present invention A ferrous composition of a particular composition is also utilized to maintain the substantially spherical shape of the pellet after carbothermal reduction, and the pellet has a good shrinkage and a high overall metallization rate and an upper metallization ratio.

The present invention has been disclosed in its preferred embodiments, and is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

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Claims (7)

A slag controlling method for producing high-layer carbothermic reduced iron, comprising the steps of: providing an iron-containing composition comprising 0.2 to 11.5 parts by weight of SiO ₂ and 0.2 to 16.2 parts by weight of Al ₂ O ₃ and 72.3 to 85.4 parts by weight of FeO or Fe ₂ O ₃ , wherein the iron composition has a weight ratio of SiO ₂ to Al ₂ O ₃ ranging from 0.71 to 7; performing a mixing step of adding coal and 0.1 And 1 part by weight of a binder in the iron-containing composition to form a mixture, wherein the molar amount of carbon contained in the coal and the molar number of oxygen contained in FeO or Fe ₂ O ₃ The ratio ranges from 1.0 to 1.1; the mixture is subjected to a pellet formation step to form the mixture into a plurality of pellets, wherein each of the pellets has a diameter ranging from 5 mm to 30 mm; Performing a pellet stacking step of stacking the pellets to form a multilayer pellet stack; and performing a carbothermal reduction step on the multilayer pellet stack, wherein the range of heating temperatures of the carbothermal reduction step is From 1400 ° C to 1550 ° C, and heating time range from 50 to 70 minutes So that the range of the whole of metallization stack of the multilayer pellet from and ranges from 74.8 to 89.8% of metallization uppermost pellet of the multilayer pellet stack is from 82.9 to 87.3%. The slag controlling method for producing high-layer carbothermic reduced iron according to claim 1, wherein the iron-containing composition further contains 0.1 to 1.0 part by weight of CaO and 0.1 to 1.0 part by weight of MgO. Producing high-layer carbon-thermal reduced iron as described in item 1 of the patent application scope A slag control method, wherein the iron-containing composition comprises iron concentrate, hematite, magnetite or limonite. The method for controlling slag forming high-layer carbothermally reduced iron according to claim 3, wherein the step of providing the iron-containing composition further comprises an adjusting step of adding pure Al ₂ O ₃ or pure SiO ₂ iron to make the composition of the SiO ₂ to Al ₂ O ₃ weight ratio range of between 0.71 to 7 is adjusted. The method for controlling slag formation for producing high-layer carbothermic reduced iron according to claim 1, wherein the weight ratio of SiO ₂ to Al ₂ O ₃ of the iron-containing composition ranges from 0.71 to 1.65. A method for controlling a slag which produces high-layer carbothermic reduced iron as described in claim 1, wherein the weight ratio of SiO ₂ to Al ₂ O ₃ of the iron-containing composition ranges from 1.97 to 7. The method for controlling slag production for producing high-layer carbothermal reduced iron according to claim 1, wherein the binder is bentonite.