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US20130074654A1 - Process for producing granular metal - Google Patents

Process for producing granular metal Download PDF

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Publication number
US20130074654A1
US20130074654A1 US13/702,409 US201113702409A US2013074654A1 US 20130074654 A1 US20130074654 A1 US 20130074654A1 US 201113702409 A US201113702409 A US 201113702409A US 2013074654 A1 US2013074654 A1 US 2013074654A1
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Prior art keywords
agglomerates
hearth
average diameter
spread
furnace
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US13/702,409
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English (en)
Inventor
Shuzo Ito
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Kobe Steel Ltd
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Kobe Steel Ltd
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Assigned to KABUSHIKI KAISHA KOBE SEIKO SHO (KOBE STEEL, LTD.) reassignment KABUSHIKI KAISHA KOBE SEIKO SHO (KOBE STEEL, LTD.) ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ITO, SHUZO
Publication of US20130074654A1 publication Critical patent/US20130074654A1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
    • B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
    • B22F9/20—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/10—Making spongy iron or liquid steel, by direct processes in hearth-type furnaces
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B11/00—Making pig-iron other than in blast furnaces
    • C21B11/08—Making pig-iron other than in blast furnaces in hearth-type furnaces
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/0046—Making spongy iron or liquid steel, by direct processes making metallised agglomerates or iron oxide
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C21B13/10—Making spongy iron or liquid steel, by direct processes in hearth-type furnaces
    • C21B13/105—Rotary hearth-type furnaces
    • 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
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
    • C22B1/16—Sintering; Agglomerating
    • 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
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
    • C22B1/24—Binding; Briquetting ; Granulating
    • C22B1/242—Binding; Briquetting ; Granulating with binders
    • C22B1/244—Binding; Briquetting ; Granulating with binders organic
    • C22B1/245—Binding; Briquetting ; Granulating with binders organic with carbonaceous material for the production of coked agglomerates
    • 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
    • C22B1/00—Preliminary treatment of ores or scrap
    • C22B1/14—Agglomerating; Briquetting; Binding; Granulating
    • C22B1/24—Binding; Briquetting ; Granulating
    • C22B1/248—Binding; Briquetting ; Granulating of metal scrap or alloys
    • 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
    • C22B5/10—Dry methods smelting of sulfides or formation of mattes by solid carbonaceous reducing agents

Definitions

  • the present invention relates to a process for producing granular metal by feeding agglomerates configured by a raw material mixture containing a metal oxide and a carbonaceous reducing agent onto a hearth, and by heating the same thereon to reduce and to melt the metal oxide in the raw material mixture.
  • the present invention is not limited to the above but can be effectively utilized also to a case of heating and reducing chromium-containing ore or nickel-containing ore, for example, to produce ferrochromium, ferronickel, or the like.
  • the term “granular” in the present invention does not necessarily mean a perfectly spherical shape, but also includes elliptical and ovoidal shapes, as well as any shapes obtained by slightly flattening these shapes, and the like.
  • the reduced iron obtained by said heating step is carburized, melted, and then coalesced in the form of granules while being separated from sub-generated slag, and the granules are cooled and solidified to obtain granular metallic iron.
  • the carbonaceous reducing agent is blended at an amount in consideration of the stoichiometric amount required to the reduction of iron oxide and the solution C content into the metallic iron to be generated, and the heating temperature is appropriately controlled in consideration of the melting point of the metallic iron upon the solution of C.
  • the carbonaceous reducing agent of the minimum amount required at the heating temperature as low as possible.
  • the present invention was made in consideration of the above circumstances, and an object thereof is to provide a technique that further improves the process for producing granular metal by heating agglomerates containing a metal oxide and a carbonaceous reducing agent, and reducing and melting the metal oxide included in the agglomerates.
  • a process for producing granular metal, according to the present invention is characterized by comprising the steps of:
  • agglomerates having an average diameter of not smaller than 17.5 mm are fed onto the hearth when the agglomerates are heated at a spread density of not lower than 0.5 on the hearth.
  • a carbonaceous material is spread on the hearth and then the agglomerates are fed on the carbonaceous material to form a single layer.
  • Iron oxide or steelmaking dust is, for example, used as the metal oxide.
  • a rotary hearth furnace is, for example, used as the moving hearth-type reduction melting furnace.
  • the moving hearth-type reduction melting furnace comprises a upstream area having a temperature controlled to be from 1300° C. to 1450° C. and a downstream area having a temperature controlled to be from 1400° C. to 1550° C.
  • downstream area is set to have a temperature higher than that of the upstream area in the moving hearth-type reduction melting furnace.
  • the average diameter of the agglomerates fed onto the hearth and the spread density of the agglomerates heated on the hearth are appropriately controlled, which improves the productivity of the granular metal.
  • FIG. 1 is a plan view schematically showing agglomerates spread on a hearth.
  • FIG. 2 includes pictures in substitution for drawings, which show states where agglomerates having the average diameter of 18.2 mm are spread.
  • FIG. 3 is a graph indicating the relationship between the distance “r” of adjacent agglomerates and the projected area ratio or spread density.
  • FIG. 4 is a graph indicating the relationship between the spread density and the amount of agglomerates fed to a furnace.
  • FIG. 5 is a graph indicating the relationship between an average diameter (Dp) of a test material (i.e., agglomerates) and reaction time.
  • Dp average diameter
  • FIG. 6 is a graph indicating the relationship between the average diameter of agglomerates and the productivity index in a case where granular metallic iron is produced from the agglomerates spread at a constant density.
  • FIG. 7 is a graph indicating the relationship between the average diameter of agglomerates and the productivity index when granular metallic iron is produced from the agglomerates (i.e., a test material) apart from each other at the constant distance “r” in the hearth.
  • the inventor of the present application conducted diligent investigations to improve the process for producing granular metal by feeding onto a hearth of a moving hearth-type reduction melting furnace and heating thereon agglomerates containing a metal oxide and a carbonaceous reducing agent to reduce and to melt the metal oxide included in the agglomerates.
  • the inventor finally found out that the productivity of the granular metal can be improved by:
  • the inventor of the present application investigated in more detail on the relationship between the size of the agglomerates and the productivity to find a new fact that the productivity of granular metal can be better improved with use of agglomerates having an average diameter of not smaller than 17.5 mm. This new finding is described with reference to FIG. 7 .
  • FIG. 7 is a graph referred to in an example to be described later, indicating the relationship between the average diameter of agglomerates and the productivity index.
  • the productivity index is a relative value to the productivity that is set to 1.00 in a case where granular metallic iron is produced with use of agglomerates having the average diameter of 17.5 mm (i.e., 1.75 cm).
  • This productivity represents a quantity of granular metallic iron produced per unit area of the effective hearth per unit time (to be detailed later).
  • the productivity index is larger and the productivity of granular metallic iron is improved by using agglomerates having an average diameter of not smaller than 17.5 mm (more specifically, an average diameter from 17.5 to 32.0 mm) in comparison to the case of using agglomerates having the average diameter of 16.0 mm (i.e., 1.60 cm).
  • FIG. 7 indicates a result of re-evaluation (i.e., simulation), on the basis of the results of various experiments, of the relationship in the cases where the distance “r” between the adjacent agglomerates on the hearth is kept constant (in other words, when the agglomerates are spread on the hearth at different spread density).
  • the spread density is the density of filled agglomerates that are spread per unit area of the effective hearth, and can be calculated from the projected area of the agglomerates on the hearth (to be detailed later).
  • FIG. 7 indicates the result of re-evaluation on the basis of the result indicated in FIG. 5 .
  • each of the actual measurement values is slightly varied. Therefore, there was applied the normalization of the relationship between by the approximation thereof with a curve that is used in the re-evaluation. This is one of the approaches of scientific analyses.
  • the most important factors in the evaluation of the productivity of granular metal are the reaction time and the yield rate (in other words, the product recovery rate). Accordingly, these properties are particularly normalized in accordance with the experimental data to conduct the re-evaluation. It is noted that the apparent density of agglomerates is another important factor that influences the productivity. However, it is preliminarily evaluated that agglomerates having a diameter from 16.0 to 32.0 mm, for example, have small variations in the apparent density as long as the agglomerates are prepared by using an identical agglomeration method, and that the apparent density can be therefore regarded as being substantially constant in the comprehensive evaluation. According to FIG.
  • the spread density of agglomerates is increased as the average diameter of the agglomerates is larger (see Table 6 below). Therefore, it is understood from FIG. 7 that the productivity of granular metallic iron can be improved by appropriately controlling the spread density, as well as by the control of the average diameter of agglomerates. Consequently, the present invention clarifies that the productivity of granular metallic iron can be improved by the control of the spread density as well as the average diameter of agglomerates.
  • Prepared in the present invention are agglomerates having an average diameter of not smaller than 17.5 mm.
  • the agglomerates are prepared by agglomerating a mixture containing a metal oxide and a carbonaceous reducing agent.
  • the metal oxide may be an iron oxide-containing material, chromium-containing ore, nickel-containing ore, or the like.
  • the iron oxide-containing material is iron ore, iron sand, steelmaking dust, nonferrous smelting residue, steelmaking waste, or the like.
  • the carbonaceous reducing agent may be a carbon-containing material such as coal or coke.
  • the mixture may be blended with an additional component such as a binder, an MgO-containing material, or a CaO-containing material.
  • the binder may be a polysaccharide (e.g., starch such as flour).
  • the MgO-containing material may be powdered MgO, those extracted from natural ore, seawater, or the like, magnesium carbonate (i.e., MgCO 3 ), or the like.
  • the CaO-containing material may be quicklime (i.e., CaO), limestone (i.e., composed mostly of CaCO 3 ), or the like.
  • the agglomerates are prepared to have an average diameter of not smaller than 17.5 mm. If the average diameter of the agglomerates is smaller, the time required to the heat transfer in the furnace is shortened in general, which also shorten the reaction time. However, when the average diameter of the agglomerates is small, it is difficult to spread the agglomerates evenly on the carbonaceous material laid on the hearth. Moreover, the particle diameter and unit mass of granular metal are inevitably decreased, which granular metal is obtained by heating the agglomerates. Such small granular metal obtained by said heating step needs to be handled with special care, which results in the difficulty in feeding the granular metal into a finery such as an electric furnace or a converter.
  • the present invention uses agglomerates having an average diameter of not smaller than 17.5 mm.
  • the average diameter of the agglomerates is preferably not smaller than 18.5 mm, more preferably not smaller than 19.5 mm, and further preferably not smaller than 20 mm.
  • the larger average diameter of agglomerates tends to deteriorate the granulation efficiency. Therefore, the agglomerates are preferably prepared to have an average diameter of not more than 31 mm.
  • the average diameter of the agglomerates is more preferably not more than 28 mm.
  • agglomerates which may be in the shape of pellets, briquettes, or the like.
  • the average diameter of the agglomerates is obtained by measuring and averaging the diameters of at least 20 particles with use of the vernier caliper. In a case where the average diameter of the agglomerates is equal to ⁇ mm, the diameters (absolute values) of the agglomerates are preferably distributed in the range of ⁇ 5 mm.
  • agglomerates need to be spread at the density of not lower than 0.5.
  • the spread density is desirably set to be as large as possible, and is preferably not lower than 0.6.
  • the spread density of agglomerates is preferably set to have the upper limit of 0.8, and is more preferably not more than 0.7.
  • the spread density of agglomerates is described in detail below.
  • the spread density of agglomerates is calculated from the projected area ratio, relative to the hearth, of the agglomerates spread on the hearth. Described below is the method of calculating the spread density with reference to FIG. 1 .
  • FIG. 1 is a plan view schematically showing agglomerates spread on the hearth.
  • the projected area ratio of the agglomerates onto the hearth can be calculated by equation (1).
  • Projected area ratio(%) [projected area of all agglomerates on hearth/effective hearth area] ⁇ 100 (1)
  • the agglomerates are assumed to have a perfectly spherical shape, and the average diameter of the agglomerates and the distance of the adjacent agglomerates are expressed by Dp and r, respectively, the projected area ratio of the agglomerates onto the hearth can be calculated by the following equation (2):
  • the projected area ratio has the maximum value and the maximum projected area ratio has a constant value (i.e., 90.69%).
  • the present invention defines, as the spread density, a relative value of the projected area ratio that is calculated in accordance with equation (2) from the average diameter Dp of the agglomerates and the distance “r” between the adjacent agglomerates.
  • FIG. 2 shows states where agglomerates having the average diameter of 18.2 mm are spread in containers each in a flat plate shape of approximately 61 cm square.
  • Case (a) in FIG. 2 shows an example of filling in a container agglomerates weighing 9.3 kg per unit area of 1 m 2 , in which case the spread density was equal to 0.4.
  • the theoretical amount of agglomerates filled at the spread density of 0.4 weighs 9.33 kg per unit area of 1 m 2 . It is therefore found out that the filled amount and the spread density in Case (a) is substantially equal to the theoretical values.
  • Case (b) in FIG. 2 shows an example of filling in a container agglomerates weighing 13.9 kg per unit area of 1 m 2 , in which case the spread density was equal to 0.6.
  • the theoretical amount of agglomerates filled at the spread density of 0.6 weighs 14.0 kg per unit area of 1 m 2 . It is therefore found out that the filled amount and the spread density in Case (b) is substantially equal to the theoretical values.
  • Case (c) in FIG. 2 shows an example of filling in a container agglomerates weighing 18.5 kg per unit area of 1 m 2 , in which case the spread density was equal to 0.8.
  • the theoretical amount of agglomerates filled at the spread density of 0.8 weighs 18.66 kg per unit area of 1 m 2 . It is therefore found out that the filled amount and the spread density in Case (c) is substantially equal to the theoretical values.
  • Case (d) in FIG. 2 shows an example of filling in a container agglomerates weighing 23.2 kg per unit area of 1 m 2 , in which case the spread density was equal to 1.0.
  • the theoretical amount of agglomerates filled at the spread density of 1.0 weighs 23.33 kg per unit area of 1 m 2 . It is therefore found out that the filled amount and the spread density in Case (d) is substantially equal to the theoretical values.
  • FIG. 3 indicates the relationship between the distance “r” of adjacent agglomerates and the projected area ratio or spread density.
  • the marks ⁇ indicate the results of projected area ratios, while the marks ⁇ indicate the results of spread densities.
  • the distance “r” between the adjacent agglomerates is increased, both the projected area ratio and the spread density of the agglomerates are reduced. There is recognized a favorable correlation between the projected area ratio and the spread density relative to the distance “r” between the adjacent agglomerates.
  • FIG. 4 indicates the relationship between the spread density and the amount of agglomerates fed to the furnace in a case where the average diameter of the agglomerates is changed in the range from 14.0 to 32.0 mm.
  • the amount of the fed agglomerates is indicated by the mass of the fed agglomerates in the effective hearth area.
  • a straight line connecting a point (A) and a point (B) indicates a range of the amount of agglomerates fed to the furnace in a case where the agglomerates have an average diameter of not smaller than 17.5 mm and are spread at the density of 0.5.
  • a straight line connecting a point (C) and a point (D) indicates a range of the amount of agglomerates fed to the furnace in a case where the agglomerates have an average diameter of not smaller than 17.5 mm and are spread at the density of 0.8.
  • the average diameter of the agglomerates and the amount of agglomerates to be fed to furnace may be adjusted to control the spread density of the agglomerates on the hearth to not lower than 0.5.
  • the agglomerates are heated in a moving hearth-type reduction melting furnace to reduce and to melt a metal oxide in the agglomerates so as to manufacture granular metal.
  • the moving hearth-type reduction melting furnace and the heating condition in the furnace are not particularly limited in the present invention, and there can be adopted a known condition.
  • the above moving hearth-type reduction melting furnace there can be used, for example, a rotary hearth furnace.
  • a rotary hearth furnace There is no particular limitation to the width of the hearth of the moving hearth-type reduction melting furnace. According to the present invention, it is possible to improve the productivity of granular metal under an economically advantageous condition even with use of an actual machine having a hearth width of not smaller than 4 m.
  • the bed material serves as a carbon resource in a case where the carbon included in the agglomerates is not sufficient, and also serves as a hearth protective material.
  • the thickness of the bed material is preferably not less than 3 mm. More specifically, in a case where the moving hearth-type reduction melting furnace is actually used, the hearth width will have several meters. Accordingly, it is difficult to spread evenly the bed material across the width direction and there may be caused variations in thickness from about 2 to 8 mm. It is preferable to spread the bed material so as to have a thickness of not less than 3 mm in order to cause no portion on the hearth not covered with the bed material.
  • the thickness of the bed material is more preferably not less than 5 mm, and further preferably not less than 10 mm.
  • the bed material having a larger thickness is particularly effective in a case of using agglomerates that have an average diameter of not less than 20 mm.
  • the thickness of the bed material is preferably not more than 30 mm, more preferably not more than 20 mm, and further preferably not more than 15 mm.
  • the carbonaceous material used as the bed material can be selected from those exemplified as the carbonaceous reducing agent.
  • the carbonaceous material desirably has a particle diameter of not more than 3.0 mm, for example. If the particle diameter of the carbonaceous material is more than 3.0 mm, the molten slag may flow down through the spaces in the carbonaceous material to reach the surface of the hearth and erode the hearth.
  • the particle diameter of the carbonaceous material is more preferably not more than 2.0 mm.
  • the proportion of the particles having a diameter of smaller than 0.5 mm is too large in the carbonaceous material, the agglomerates will be buried in the bed material to lead to the deteriorations in heating efficiency as well as in productivity of granular metal, which is not preferable.
  • the agglomerates are preferably fed onto the hearth so as to form a single layer over the bed material that is spread on the hearth.
  • One general idea for the increase in the production quantity of granular metallic iron will be increasing the amount of agglomerates to be fed to the furnace.
  • the agglomerates are stacked into two or more layers on the hearth.
  • the upper agglomerates receive sufficient heat from a furnace body to be reduced and melted, while sufficient heat is not fed to the lower agglomerates, which are likely to cause residual portions not having been reduced.
  • a pellet leveler or the like may be used to control the agglomerates to be spread on the hearth so that the agglomerates are evenly spread over the effective hearth across the width direction thereof before the agglomerates fed to the furnace enter a thermal reaction zone.
  • the agglomerates are heated in a moving hearth-type reduction melting furnace to reduce and to melt the metal oxide included in the agglomerates. More specifically, the agglomerates are fed onto the hearth, reduced in the solid state at a predetermined temperature, and further continuously heated until being melted, so as to obtain manufactured slag (i.e., oxide) comprising impurities and granular metallic iron.
  • the agglomerates on the hearth receive heat from combustion flames of a plurality of burners installed in an upper portion in the furnace (e.g., on a ceiling) or on a side wall, or radiation heat from a refractory material in the furnace, which is heated to a high temperature. The received heat is transferred from the peripheral portions to the inner portions of the agglomerates so as to progress the reduction reaction in the solid state.
  • the reduction reaction progresses while the agglomerates being kept in the solid state.
  • microscopic particles of reduced iron in the agglomerates which have been already reduced in the solid state, are carburized and then coalesced to each other in the process of being melted, so as to form granular metallic iron while being separated from the impurities (i.e., slag components) in the agglomerates.
  • the temperature of the upstream area in the furnace is preferably controlled to be at approximately 1300° C. to 1450° C. so as to cause the iron oxide in the agglomerates to be reduced in the solid state.
  • the temperature of the downstream area in the furnace is preferably controlled to be at approximately 1400° C. to 1550° C. so as to cause the reduced iron in the agglomerates to be carburized, melted, and coalesced. If the furnace is heated to be higher than 1550° C., heat is excessively applied to the agglomerates to exceed the rate of the heat transferred into the agglomerates. In this case, the agglomerates are partially melted before being completely reduced in the solid state. As a result, the reaction progresses rapidly to cause a molten reduction reaction, which generates abnormal slag formation.
  • the downstream area in the furnace may be set to a temperature higher than that in the upstream area in the furnace.
  • the productivity of the case where the agglomerates are heated to reduce and to melt the metal oxide to produce granular metal is evaluated by the production quantity (ton) of the granular metal per unit area (m 2 ) of the effective hearth per unit time (time), as expressed by equation (3) below.
  • equation (3) the production quantity of granular metal (granular-metal ton/time) is expressed by equation (4) below.
  • Production quantity of granular metal(granular-metal-ton/time) amount of agglomerates charged (agglomerates-ton/time) ⁇ mass of granular metal produced from 1 ton of agglomerates (granular-metal-ton/agglomerates-ton) ⁇ product recovery rate (4)
  • the product recovery rate is calculated as a proportion of granular metallic iron having a diameter of not smaller than 3.35 mm to the total mass of the granular metal obtained [mass of granular metallic iron having a diameter of not smaller than 3.35 mm/total mass of granular metallic iron ⁇ 100].
  • a test material i.e., agglomerates
  • the productivity of each of the agglomerates is indicated as a relative value (i.e., productivity index) in a case where the productivity of the standard agglomerates is set to 1.00.
  • Agglomerates were prepared from a raw material mixture containing a metal oxide and a carbonaceous reducing agent, and the agglomerates were fed onto a hearth of a moving hearth-type reduction melting furnace and were heated thereon to reduce and to melt the metal oxide in the raw material mixture, so as to produce granular metallic iron.
  • iron ore having the component compositions listed in Table 1 below was used as the metal oxide
  • coal having the component compositions listed in Table 2 below was used as the carbonaceous reducing agent, to produce the agglomerates.
  • the mixture containing the iron ore and the coal was blended with flour serving as a binder and an auxiliary material such as limestone or dolomite, to produce agglomerates (i.e., test materials) in the shapes of pellets having different average diameters.
  • the blend compositions (i.e., weight percentages) of the test materials are listed in Table 3 below.
  • the longer diameters and the shorter diameters of the test materials were measured with use of a vernier caliper to calculate the average diameters, which are listed in Table 4 below.
  • Each of the average diameters of the test materials is obtained by measuring the sizes of 20 particles of each of the test materials.
  • the unit mass of each of the test materials is equal to an average value obtained by measuring the mass of 20 particles.
  • the apparent density of each of the test materials is obtained by immersing the agglomerates in a liquid (i.e., mercury) and measuring buoyant forces thereof.
  • test materials thus obtained and having the different average diameters was heated in a small heating furnace on a laboratory scale (i.e., the temperature in the furnace being set to 1450° C.) to reduce and to melt the iron ore included in the corresponding test material, in order to measure time required for the reaction (i.e., reaction time).
  • reaction time time required for the reaction
  • FIG. 5 indicates the relationship between the average diameter (Dp) and the reaction time of the test material.
  • a dotted curve shows an approximated curve including plotted points, which is expressed by a quadratic of the average diameter of the test material. As apparent from FIG. 5 , as the average diameter of the test material increases, the reaction time is longer.
  • the reaction time and the product recovery rate were normalized to comprehensively evaluate the productivity of a case where the distance between the adjacent particles of the test material is changed (see Experimental Example 2 to be described later), or of a case where the spread density of the test material is changed (see Experimental Example 3 to be described later).
  • test materials which have average diameters of 16.0 to 28.0 mm (i.e., 1.60 to 2.80 cm) and are spread at a constant density on a hearth, were heated in an actual moving hearth-type reduction melting furnace to produce granular metallic iron.
  • Comprehensively investigated was how the average diameter of the test material influences on the productivity of granular metallic iron thus produced.
  • a rotary hearth furnace was used as the moving hearth-type reduction melting furnace, and each of the test materials was fed onto the hearth at the spread density of 0.66 and was heated thereon to reduce and to melt iron ore so as to produce granular metallic iron.
  • the temperature of the upstream area in the furnace was set to 1400° C. and the temperature of the downstream area thereof was set to 1470° C.
  • the iron ore in the test material is reduced in the solid state.
  • microscopic particles of reduced iron which are generated and melted in the test material, are carburized, melted, and eventually coalesced so as to separate molten iron from slag.
  • the spread density of the test material on the hearth was controlled by regulating the amount of the test material fed to the furnace and the moving speed (i.e., rotating speed) of the hearth. More specifically, the moving speed of the hearth was determined such that the iron ore was reduced and melted in the heating zone under an atmospheric condition set in accordance with the result of the preliminary experiment. The supply amount of the test material was regulated in consideration of this moving speed, so that the spread density of the test material on the hearth was controlled to 0.66. Table 5 below shows the distance “r” between the adjacent particles of the test materials as reference values.
  • productivity index The productivity of granular metallic iron produced by reducing and melting each of the test materials was calculated in accordance with above equation (3), and the productivity of each of the test materials was indicated as a relative value (i.e., productivity index), assuming that the productivity of the test material No. 12 (i.e., standard agglomerates) has a standard value (i.e., productivity index equal to 1.00).
  • productivity index The productivity indices of the respective test materials are listed in Table 5 below. Further, FIG. 6 indicates the relationship between the average diameter and the productivity index of the test material.
  • the productivity can be improved by setting the average diameter of the test material to be not smaller than 17.5 mm in comparison to the case of setting the average diameter of the test material to 16.0 mm.
  • the productivity is gradually improved as the average diameter of the test material increases, and the productivity index reaches the maximum value in the case where the average diameter of the test material equal to 22.0 mm.
  • the productivity of granular metallic iron tends to be gradually deteriorated.
  • the productivity will be deteriorated because the reaction time is longer with the test material of a larger size. Accordingly, when the spread density is kept constant, it is found that the productivity can be improved by setting the average diameter of the test material to the range from 17.5 to 26.0 mm in comparison to the case of using the test material having the average diameter of 16.0 mm.
  • a rotary hearth furnace was used as the moving hearth-type reduction melting furnace, and each of the test materials, which have the average diameters listed in Table 6 below and were fed onto the hearth, was heated to reduce and to melt iron ore so as to produce granular metallic iron.
  • the heating condition in the furnace was set identically with that of Experimental Example 2 described earlier.
  • the spread densities of the test materials on the hearth are listed in Table 6.
  • the productivity of the granular metallic iron produced by reducing and melting each of the test materials was calculated in accordance with equation (3) above, and the productivity of each of the test materials was indicated as a relative value (i.e., productivity index), assuming that the productivity of the test material No. 22 (i.e., standard agglomerates) has a standard value (i.e., 1.00).
  • productivity index i.e., productivity index
  • the productivity indices of the respective test materials are listed in Table 6 below. Further, FIG. 7 indicates the relationship between the average diameter and the productivity index of the test material.
  • the spread density of the test material on the hearth can be increased by setting the average diameter of the test material to be not smaller than 17.5 mm.
  • the productivity of the granular metallic iron can be improved by increasing the average diameter of the test material in comparison to the case of setting the average diameter of the test material to 16.0 mm. In other words, the productivity is gradually improved as the average diameter of the test material increases, and the productivity index reaches the maximum value in the case where the average diameter of the test material is equal to 24.0 mm.
  • the productivity of the granular metallic iron tends to be gradually deteriorated.
  • the productivity will be deteriorated because the reaction time is longer with the test material of a larger size. Accordingly, it is found that the productivity can be improved by setting the average diameter of the test material to the range from 17.5 mm to 32.0 mm in comparison to the case of using the test material having the average diameter of 16.0 mm.
  • the present invention is applicable to improve the productivity of the granular metal.

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  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
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  • Manufacture Of Iron (AREA)
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JP2010130124A JP5503420B2 (ja) 2010-06-07 2010-06-07 粒状金属の製造方法
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US20160237514A1 (en) * 2013-09-25 2016-08-18 Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) Method for manufacturing iron nuggets
US10072313B2 (en) 2014-12-24 2018-09-11 Sumitomo Metal Mining Co., Ltd. Method for smelting nickel oxide ore
US10301704B2 (en) 2015-02-24 2019-05-28 Sumitomo Metal Mining Co., Ltd. Method for smelting saprolite ore
US10364480B2 (en) * 2014-10-06 2019-07-30 Sumitomo Metal Mining Co., Ltd. Method for smelting nickel oxide ore
US10626480B2 (en) 2017-05-24 2020-04-21 Sumitomo Metal Mining Co., Ltd. Method for smelting oxide ore
US11479832B2 (en) 2016-04-22 2022-10-25 Sumitomo Metal Mining Co., Ltd. Method for smelting oxide ore
US11608543B2 (en) 2016-04-27 2023-03-21 Sumitomo Metal Mining Co., Ltd. Oxide ore smelting method

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JP5839090B1 (ja) * 2014-07-25 2016-01-06 住友金属鉱山株式会社 ニッケル酸化鉱の製錬方法、ペレットの装入方法
JP6455374B2 (ja) * 2015-09-08 2019-01-23 住友金属鉱山株式会社 ニッケル酸化鉱の製錬方法
JP6447429B2 (ja) * 2015-09-08 2019-01-09 住友金属鉱山株式会社 ニッケル酸化鉱の製錬方法
JP6477371B2 (ja) * 2015-09-08 2019-03-06 住友金属鉱山株式会社 ニッケル酸化鉱の製錬方法
CN107354257A (zh) * 2017-07-10 2017-11-17 中冶南方工程技术有限公司 一种金属铁的生产方法
JP7147409B2 (ja) 2018-09-20 2022-10-05 住友金属鉱山株式会社 酸化鉱石の製錬方法
JP7533120B2 (ja) * 2020-10-26 2024-08-14 住友金属鉱山株式会社 酸化鉱石の製錬方法
JP7533160B2 (ja) * 2020-11-25 2024-08-14 住友金属鉱山株式会社 酸化鉱石の製錬方法
JP2023147090A (ja) * 2022-03-29 2023-10-12 住友金属鉱山株式会社 ニッケル酸化鉱石の製錬方法
JP2023147088A (ja) * 2022-03-29 2023-10-12 住友金属鉱山株式会社 ニッケル酸化鉱石の製錬方法
JP2023147089A (ja) * 2022-03-29 2023-10-12 住友金属鉱山株式会社 ニッケル酸化鉱石の製錬方法
AU2024241987A1 (en) 2023-03-31 2025-10-02 Sumitomo Metal Mining Co., Ltd. Method for smelting nickel oxide ore

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US6413295B2 (en) * 1998-11-12 2002-07-02 Midrex International B.V. Rotterdam, Zurich Branch Iron production method of operation in a rotary hearth furnace and improved furnace apparatus
US20040173054A1 (en) * 2001-07-12 2004-09-09 Osamu Tsuge Method of manufacturing metal iron

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160237514A1 (en) * 2013-09-25 2016-08-18 Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) Method for manufacturing iron nuggets
US10364480B2 (en) * 2014-10-06 2019-07-30 Sumitomo Metal Mining Co., Ltd. Method for smelting nickel oxide ore
US10072313B2 (en) 2014-12-24 2018-09-11 Sumitomo Metal Mining Co., Ltd. Method for smelting nickel oxide ore
US10301704B2 (en) 2015-02-24 2019-05-28 Sumitomo Metal Mining Co., Ltd. Method for smelting saprolite ore
US11479832B2 (en) 2016-04-22 2022-10-25 Sumitomo Metal Mining Co., Ltd. Method for smelting oxide ore
US11608543B2 (en) 2016-04-27 2023-03-21 Sumitomo Metal Mining Co., Ltd. Oxide ore smelting method
US10626480B2 (en) 2017-05-24 2020-04-21 Sumitomo Metal Mining Co., Ltd. Method for smelting oxide ore

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RU2544979C2 (ru) 2015-03-20
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CA2799548A1 (en) 2011-12-15
NZ603956A (en) 2014-02-28
CN102933727A (zh) 2013-02-13
AU2011262982B2 (en) 2014-02-20
TW201211264A (en) 2012-03-16
RU2012157181A (ru) 2014-07-20
WO2011155417A1 (ja) 2011-12-15
CL2012003380A1 (es) 2013-05-24
JP2011256414A (ja) 2011-12-22
CN102933727B (zh) 2014-12-24
AU2011262982A1 (en) 2013-01-10
JP5503420B2 (ja) 2014-05-28
EP2578703A1 (en) 2013-04-10
MX2012014337A (es) 2013-04-09

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