EP0015085A1 - Mélange de matières premières et procédé de fabrication de minerais auto-fusibles frittés - Google Patents

Mélange de matières premières et procédé de fabrication de minerais auto-fusibles frittés Download PDF

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Publication number
EP0015085A1
EP0015085A1 EP80300299A EP80300299A EP0015085A1 EP 0015085 A1 EP0015085 A1 EP 0015085A1 EP 80300299 A EP80300299 A EP 80300299A EP 80300299 A EP80300299 A EP 80300299A EP 0015085 A1 EP0015085 A1 EP 0015085A1
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Prior art keywords
sio
mix
fine grains
content
size
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German (de)
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EP0015085B1 (fr
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Kiyoshi Tashiro
Yohzoh Hosotani
Tsukasa Takada
Hideaki Souma
Masami Wajima
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Nippon Steel Corp
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Nippon Steel Corp
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Priority claimed from JP967979A external-priority patent/JPS55104439A/ja
Priority claimed from JP5930879A external-priority patent/JPS55152134A/ja
Priority claimed from JP6284779A external-priority patent/JPS55154535A/ja
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    • 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

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  • This invention relates to an improved raw materials mix for producing self-fluxing, sintered ores, and more particularly, to an improved process for producing low-slag, sintered ores which are resistant to disintegration, and the improved self-fluxing sintered ores resulting from the process.
  • the process is based on the finding that the Si0 2 content of the fine grains of the new materials mix is important to the production of improved self-fluxing, sintered ores.
  • Sintereing by a common Dwight-Lloyd sinter machine generally comprises preparing a raw materilas mix of iron ore, limestone, silica, miscellaneous other materials and coke, agglomerating the mix in the presence of water, and charging the resulting agglomerate into the sinter machine.
  • the surface layer of the sinter bed is ignited in an ignition furnace, and suction is applied downwardly of the sinter bed for a period of about 20 minutes during which the whole thickness of the sinter bed is sintered, starting from the surface layer and ending with the bottom layer.
  • the RDI value which expresses, as a weight percentage of grains below 3 min in size
  • the ease with which the sintered ore disintegrate when subjected to a reducing atmosphere in a blast furnace at a temperature in the range of from 400 to 600°c according to the conventional technique either the coke content of the mix or its slag content (expressed as the sum of Ca0 and SiO 2 ) is increased.
  • the first method i.e. increasing the coke content, is effective in improving the RDI value, but lowers the gas permeability of the sinter bed, thus decreasing the productivity and reducibility while increasing coke consumption.
  • the second method i.e.
  • slag content (expressed as the sum of CaO and SiO 2 ), achieves the intended purpose, but calls for more slag to be charged into the blast furnace, thus increasing the blast furnace fuel consumption.
  • blast furnaces are charged with about 300 kg of slag per ton of pig, and this amount is far greater than the amount necessary for furnace operations.
  • excess slag is primarily due to the high content of SiO 2 carried with the furnace charge, especially itsmajor ingredient, i.e., the sintered ore.
  • a small SiO 2 content of sintered ore denotes a low strength and a low yield of sintered ore. To avoid this problem, it has been necessary to keep the SiO 2 content of the sintered ore in the range of from about 5.6 to about 6.0 wt%, inclusive.
  • the process of this invention for producing a self-fluxing sintered ore is based on the finding that SiO 2 contained in the fine grains of the raw materials mix melts easily in the sintering operation to form a melt, and that even a small amount of such SiO 2 can bind and agglomerate the coarse grains of the iron ore to give a strength which is such that the resulting sintered ore will not disintegrate under the load (the weight of furnace charge) when it is charged into a blast furnace.
  • the invention defined above provides a novel process for producing a sintered ore with a reduced slag content (Ca0 plus SiO 2 ) without increasing the RDI value of the ore, such sintered ore of low slag content requiring less thermal energy for melting in a blast furnace.
  • a further feature of the invention is that the process of the invention produces a sintered ore the SiO 2 content of which is below 5.4 wt% without adverse effects on the quality and productivity of the ore.
  • a raw materials mix for sintering is about 6% water, which accelerates the formation of pseudo- particles that increase the gas permeability of the sinter bed.
  • Each pseudo-particle comprises a coarse grain core about 1 to 5 mm in size which is surrounded by fine grains below 1 mm in size adhering to the core.
  • the quantity of initially fused grains gradually increases by melting adjacent coarse grains, but because the sintering materials stays in a high temperature range only for a short period of time, the coarse grains do not fuse completely and the resulting melt is not a uniform mixture of fine and coarse grains but contains a higher proportion of the initially fused fine grains when it has coagulated and formed slag bonds. Therefore, to form a required amount of melt quickly, it is necessary that the fine grains below 1 mm in size surrounding a coarse grain should contain as many starting points as possible which melt at low temperatures.
  • the melt basically consists of SiO 2 , CaO and iron oxides, and, since the greater part of the sintering material is made up of iron ore as the source of iron oxides, the fine grains surrounding a coarse grain unavoidably contain a large proportion of iron oxides. Accordingly, the more SiO 2 and CaO sources which are present in the fine grains, the more easily is a melt is formed. This may be achieved by using a raw material which contains a large proportion of SiO 2 and Ca0 in only fine grains. However no such iron ore is found in nature, and, therefore, a practical method is to add fine grains of silica, serpentite, peridotite and Ni-slag as SiO 2 sources and fine grains of limestone as a CaO source.
  • the first embodiment of the process of this invention is a process for producing self-fluxing, sintered ores using a raw materials mix comprising at least 25 wt% of fine grains below 1 mm in size and not more than 5.4 wt% of "SiO 2 in terms of sintered ore product", as defined above, said process being characterized by controlling the SiO 2 content of said fine grains to be at least 50 wt% of the total SiO 2 content of the mix, and sintering the thus controlled mix.
  • FIGS. 1, 2 and 3 each show the relationship of the weight of SiO 2 and Ca0 for each grain size (as percentage of the total content of each size) to the basicity (CaO/SiO 2 ratio by weight) for each grain size.
  • the grain size scale of each figure is divided into six ranges, namely: -0.25 mm, 0.25 ⁇ 0.5 mm, 0.5 ⁇ 1 mm, 1 ⁇ 2 mm, 2 ⁇ 5 mm, and 5 ⁇ 10 mm.
  • the premix has an average basicity (CaO/SiO 2 ) of about 1.33:1.
  • Tables 1, 2 and 3 (below) each show the grain size distribution of the mix and the contents of CaO and SiO 2 , respectively, for each grain size as percentages of the CaO and SiO 2 contents of the mix.
  • tile mix for the conventional process contains more CaO in the range of from 1 to 2 mm and of from 0.25 to 0.5 mm than in the other ranges, but its SiO 2 content is unifromly distributed over the six ranges.
  • Table 1 shows, both the Ca0 and SiO 2 contents, as percentages of the Ca0 and SiO 2 contents of the mix, are below 50% in tile case of gram sizes below 1 mm.
  • the mix for the process of this invention is characterized by a CaO distribution for grain sizes below 1 mm which is similar to that obtained with the mix of the conventional process and yet contains more SiO 2 in grains below 1 mm in size than does the conventional mix.
  • the mix for the process of this invention is controlled so that is contains not more than 5.4 wt% of SiO 2 in terms of the SiO 2 content of the sintered ore product.
  • the grains of the mix below 1 mm in size have a low basicity (CaO/SiO 2 ).
  • the SiO 2 content for grain sizes below 1 mm, as a percentage of the total SiO 2 of the mix, is higher than 50%.
  • FIG. 3 illustrates another mix to be used in the process of this invention.
  • the mix is such that the SiO 2 content of fine grains below 1 mm in size is at least 50% of the total SiO 2 content of the mix, and that the SiO 2 content of the mix is 5.2% in terms of the SiO 2 content of the sintered ore product.
  • the mix is characterized in that grains below 1 mm in size have a higher SiO 2 content and a lower basicity (CaO/SiO 2 ) than grains below 1 mm in size in the conventional mix (see FIG 1). It follows that, as shows in Table 5 (above), the SiO 2 content of grains below 1 mm in size as compared with the total SiO 2 content of the mix is at least 50% as with the mix the characteristics of which are shown in Table 2 (above).
  • the SiO 2 content of the mix to be used in the process of this invention is so controlled that it is not more than 5.4% as converted to a value for sintered ore product. Such conversion is necessary for determining accuratly the SiO 2 content of the mix because some portions of the mix are eliminated as gas and dust in the course of sintering.
  • No general conversion formula can be set because the type and amount of the ingredients to be eliminated from the mix vary slightly with the composition of the mix and the sintering conditions, but it can be approximated by the following relationship: in which: Y is the SiO 2 content (wt%) of the sintered ore product, X is the SiO 2 content (wt%) of the mix, and a and b are constants, generally 1.1 and not more than 0.2, respectively, which canbe determined empiracally on the basis of actual records of sintering operations.
  • the mix for use in the process of this invention contains at least 25%, preferably from 25 to 60%, of fine grains below 1 mm in size. If the content of fine grains below 1 mm in size is lower than 25%, not enough slag bonds are formed by sintering to provide a strong sintered ore. If the content of fine grains below 1 mm in size exceeds 60%, the gas permeability of the sinter bed is decreased but this will not sacrifice the productivity of the process of this invention if the agglomeration operation is enhanced by longer agglomeration or if a binder such as quicklime or bentonite is added.
  • Sintered ores were produced from themix described above with varying proportions of SiO 2 in grains below 1 mm in size relative to the total SiO 2 of the mix, and the RDI values of the products were plotted in FIG 4, from which one can understand that the RDJ value is greatly and suddenly improved when the SiO 2 content of mix grains below 1 mm in size exceeds 50% of the total SiO 2 content of the mix. This is probably because an increased reactive area of the SiO 2 -containing mix causes rapid and uniform formation of SiO 2 slag, the basic component of the slag bond which binds the particles or iron oxide together and governs the strength of the sintered are product. As a result, a low-slag sintered ore containing not more than 5.4% of SiO 2 is produced.
  • the second embodiment of the process of this invention is a process for producing a low slag-content sintered ore using a raw materials mix for a self-fluxing sintered ore comprising at least 25 weight % of fine grains below 1 mm in size, said process being characterized by lowering the SiO 2 content of the mix to not more than CaO tu SiO 2 basicity of said fine grains to be below 1.3:1, and sintering the thus controlled mix.
  • the sintered ore produced by the second embodiment of this invention is a self-fluxing (basic) sintered ore which contains not more than 5.4 wt% of SiO 2 , and the fine grains below 1 mm in size which account for at least 25% of the ore are characterized by having a basicity (CaO/SiO 2 ) below 1.3:1.
  • the composition of the fine grains of the mix below 1 mm in size is the composition of the fine grains of the mix below 1 mm in size.
  • the lower the basicity (CaO/SiO 2 ratio) of fine grains of the mix below 1 mm in size the higher the reduction strength of the sintered ore, and this effect is particularly conspicuous when the fine grains have a basicity below 1.0:1.
  • two raw materials mixes with the same average composition will provide sintered ores of different reduction strengths if the fine grains below 1 mm in size have different basicities.
  • a mix in which the fine grains below 1 mm in size have a higher basicity provides a sintered ore of higher reduction strength than a mix in which such fine grams have a lower basicity.
  • the necessary and sufficient requirement for high quality and productivity of sintered ore is that the proper conditions of the amount and constituents (SiO 2 and Ca0) of fine grains of a raw materials mix for sintering below 1 mm in size should be satisfied.
  • a low-slag sintered ore By reducing the SiO 2 and Ca0 contents of coarse grains more than 1 mm in size which have not been involved in the formation of a "bond", and thereby decreasing the total SiO 2 and Ca0 contents of the raw matcrial, a low-slag sintered ore can be prepared which contains not more than 5.4 wt% of SiO 2 but which has previously been difficult to produce commercially due to low quality and productivity.
  • the SiO 2 and CaO contents of the coarse grains are reduced not directly but indirectly by decreasing the SiO 2 and Ca0 contents of the total mix, and then compensating for the required amounts of SiO 2 and CaO in the fine grains below 1 mm in size. Therefore, a 40 kg-pot test was conducted to determine the quantitative relationship between the SiO 2 and Ca0 contents of fine grains below 1 mm in size and the quality of the sintered ore product. The results of the test are shown in FIG 6 of the drawings.
  • FIG 6 is a graph plotting the RD1 values of sintered ore products produced by varying the SiO 2 and CaO contents of fine grains of a raw materials mix below 1 mm in size.
  • the weight of SiO 2 contained in fine grains below 1 mm in size is plotted as a percentage of the components of the mix (dry).
  • This factor is defined by the following formula (the factor will hereunder be referred to as [SiO 2 ]in -1 mm): wherein A is the percentage by weight of the line grains below 1 mm in size contained in the mix, and B is the percentage by weight of SiO 2 contained in the fine grains below 1 mm in size.
  • the weight of CaO contained in fine grains below 1 mm in size is plotted as a percentage of the components of the mix(dry).
  • the RD1 values of the resulting sintered ore products are indicated by numerals in the graph.
  • the basicity . (CaO/SiO 2 ratio) of the fine grains below 1 mm in size is shown as a solid line sloping upwards to the right, and the sum of the Ca0 and SiO 2 contained in the fine gmins below 1 mm in size is shown as a dotted line sloping upwards to the left.
  • the area of RDI ⁇ 40 is hatched and it enclosed the region where [SiO 2 ] in -1 mm is at least 2.4 and the CaO/SiO 2 ratio of fine grains below 1 mm in size is not more than 1.3:1.
  • the region where [SiO 2 ] in -1 mm is at least 3.0 and the CaO/SiO 2 ratio of fine grains below 1 mm in size is not more than 1.0:1 is characterized by very desirable RDI values ( ⁇ 30).
  • the [SiO 2 ] in -1 mm should be higher than a certain value and that the CaO/SiO 2 ratio of line grains below 1 mm in size should not exceed a given value.
  • the total SiO 2 content of the mix should naturally be smaller than that of the conventional mix, and this requirement unavoidably constitutes a limit to the increase in the level of [SiO 2 ] in - 1 mm.
  • the region where [SiO 2 ] in -1 mm exceeds 5.0 in FIG 6 is obtainable only in a laboratory by selecting only iron ores which arc extremely low in SiO 2 content, blending them with fine powders of SiO 2 sources and sintering the resulting mix. In commercial operations where selection of such ores is difficult, there is little possibility of obtaining the stated range.
  • the strength at ordinary temperatures (shatter index) of a sintered ore is directly correlated with the sum of the CaO and SiO 2 contained in fine grains below 1 mm in size, and, therefore, the value of the sum cannot be made excessively low.
  • the level of SiO 2 in -1 mm of the mix being at least 2.4, if the sum of CaO and SiO 2 contained in fine grains below 1 mm in size is smaller than 4.0, the sintered ore product has a tendency to exhibit low strength at ordinary temperatures (shatter index), making it necessary to implement separate provisions for increasing the shatter index by, for instance, incorporating more coke in the mix.
  • the technique of this invention can be easily implemented within the hatched area of FIG 6 where the [SiO 2 ] in -1 mm value is at leat 2.4 and the CaO/SiO 2 ratio of fine grains below 1 mm in size is not more than 1.3:1, especially in the dotted area where the [SiO 2 ] in -1 mm value is between 2.4 and 3.0, the CaO/SiO 2 ratio of fine grains below 1 mm in size is not greater than 1.3:1 and the sum of CaO and SiO., contained in the fine grains below 1. mm in size is at least 4.0. It is to be noted again that the mix for use in the process of this invention generally contains from 23 to 60 wt% of fine grains below 1 mm in size.
  • the necessary and sufficient requirement for high quality and productivity of the sintered ore is that the proper conditions with respect to the amount and constituents (SiO 2 , CaO and Al 2 O 3 ) of fine grains of a raw materials mix for sintering below 1 mm in size should be satisfied.
  • a low-slag sintered ore By reducing the SiO 2 and CaO contents of coarse grains larger than 1 mm in size which have not been involved in the formation of a "bond", and therby decreasing the total SiO 2 and CaO contents of the raw material, a low-slag sintered ore can be prepared which contains not more than 5.4 wt% of SiO 2 but which has previously been difficult to produce commercially due to low quality and producivity. However, it is substantially impossible in practice selectively to eliminate SiO 2 and Ca0 from only the coarse grains of the raw material below 1 mm in size.
  • FIG 8 is a graph plotting the RDI values of sintered ore products produced by varying the Si0 2 , Ca0 and Al 2 0 3 contents of fine grains of a raw materials mix which are below 1 mm in size. We have plotted on the x-axis the weight of the SiO 2 contained in fine grains below 1 mm in size minus the weight of Al 2 0 3 contained in the fine grains as a percentage of the components of the mix(dry).
  • This factor is defined by the following formula (the factor will hereunder be referred to as [SiO 2 - Al 2 0 3 in -1 mm): wherein A is the precentage by weight of the fine grains below 1 mm in size contained in the mix, B is the percentage by weight of Si0 2 contained in the fine grains below 1 mm in size, and C is the percentage by weight of Al 2 O 3 contained in the fine grains below.1 mm in size.
  • the region where the SiO 2 -Al 2 O 3 ] in -1mm value is at least 2.4 and the CaO/(SiO 2 - Al 2 0 3 ) ratio or fine grains below 1 mm in size is not greater than 1.8:1 is characterized by very desirable RDI values ( ⁇ 30).
  • the change in the Al 2 0 3 content of a raw material for sintering is generally smaller than that in the SiO 2 content, and furthermore, in practice iron ores having an extremely low content of Al 2 0 3 are not generally available in large quantities, Therefore, it is unavoidable that the level of SiO 2 - Al 2 0 3 in -1 mm must be increased by increasing the SiO 2 content of fine grains below 1 mm in size.
  • the sintered ore produced by the process of this invention is of low SiO 2 content, the total SiO 2 content of the raw materials mix should naturally be smaller than that of the conventional mix, and this requirement unavoidably constitutes a limit to the available increase in the level of SiO 2 - Al 2 O 3 ] in -1 mm.
  • the strength at ordinary temperatures (shatter index) of the sintered ore is directly correlated with the sum of CaO and SiO 2 contained in fine grains below 1 mm in size, and, therefore, the value of the sum cannot be made excessivley low.
  • level of SiO 2 - Al 2 O 3 ] in -1 mm of a raw materials mix being at least 1.8, if the value of the CaO/(Sio 2 - Al 2 O 3 ) ratio of the fine grains below 1 mm in size is smaller than 1.0:1, the sum of the Ca0 and SiO 2 contained in said fine grains decreases, and the sintered ore product has a tendency to exhibit a low strength at ordinary temperatures (shatter index), making it necessary to implement separate provisions for increasing the shatter index by, for instance, incorporating more coke in the mix.
  • the level of the CaO/(SiO 2 - Al 2 0 3 ) ratio of fine grains below 1 mm in size should not be below O.5:1 because, otherwise, sintered ore which is very low in strength at ordinary temperatues is produced.
  • the technique of this invention can be easily implemented within the hatched area of FIG 8 Where the [SiO 2 - Al 2 0_ ] in -1 mm values are at least 1.S and the Cao/ Sio 2 - Al 2 0 3 ) ratio of fine grains below 1 mm in sizeare not greater than 2.0:1 especially in the dotted area Where the [ SiO 2 -Al 2 O 3 ]in -1 mm values are between 1.Sand 2.4and the CaO / (Sio 2 -Al 2 O 3 ) rates between 0.5:1 preferably 1.0:1 and 2.0:1.
  • the raw materials mix used in Example 1 according to one embodiment of the process of this invention incorporated fine grains below 1 mm in size) of silica containing at least 90% of Si0 2 so that the Si0 2 content of the mix was not more than 5.4%in terms of sintered ore product.
  • Example 2 The raw materials mix used in Example 2 according to another embodiment of this invention likewise incorporated fine grains (below 1 mm in size) of silica containing at least 90%of Si0 2 ,but it contained a smaller amount of silica and limestone so that the Si0 2 content of the mix was not more than 5.2% in terms of sintered ore product.
  • Tables 4,5 and 6 arc keyed to Table1, 2 and 3, respectively.
  • the compositions of the principal ingredients of each mix are identified in Table 8 below.
  • the process of this invention is comparable with, or even superior to, the conventional sintering process with respect to productivity, coke consumption, shatter index and other factors while it can greatly reduce the RDI value of the sintered product, or reduce the Si0 2 content of the.sintered product to below 5.4% without greatly increasing its RDI value.
  • Comparative Examples 2 and 3 and Examples 3to 7 of this invention are described hereunder. Sevendifferent raw materials mixes each comprising iron ores, limestone, silica, coke and return fines were aggolomerated in the presence of water, and the resulting agglomerates were charged into a 40 kg test pot at a negative pressure of 1700 mmll 2 0 to produce seven different sintered ores. The description of the ingredients of each mix and the composition of each ingredient are shown in Tables 9 to 12 (Comparison Example 2 and Examples 3 to 5) and Tables 19 to 22 (Comparison example 3 and Examples 6 and 7).
  • the proportions of the ingredients of the mixes are indicated in Table 13 (Comparison Example 2 and Examples 5 to 5) and in Table 23(Comparison Example 3 and Examples 6 and 7).
  • Tables s 14 to 17 arc keyed to the data on the proportions of ingredients set forth in Table 13 for Comparative Example 2 and Examples 3 to 5, respectively, and each table shows the SiO 2 and Ca0 contents of the raw materials mix and the sintered ore product.
  • Tables 14 to 17 the data on the Si0 2 content, the CaO content and the CaO/SiO 2 ratio of the mix are classified under coarse grains largerthan 1 mm in size and fine grains below 1 mm in size.
  • Tables 24 to 26 are keyed to the data on the proportions of ingredients set forth in Table 23 for Comparative Example 3 and Examples 6 and 7, respectively, and each table shows the SiO 2 , Ca0 and Al 2 0 3 contents and-the Ca0/Si0 2 ratios of the raw materials mix and sintered ore product, and the (Si0 2 -Al 2 0 3 ) contents and Ca0/(Si0 2 - Al 2 0 3 )ratios of fine grains (below 1 mm in size) of the mix.
  • Y which is the Si0 2 content (wt%) of the sintered ore produce
  • X which is the Si0 2 content (wt%) of the raw materials mix
  • aand bare constants generally 1.1 and not more than 0.2, respectively, which can be determined empirically on the basis of actual records of sintering operations.
  • the raw materials mix prepared in Comparative Example 2 is such that the amount of silica containing at least 90%of Si0 2 is simply decreased to lower the Si0 2 content in terms of sintered ore product from the ordinary range of 5.6 t.o 6.0 wt% down to 5.4 wt%.
  • the level of [Si0 2 in -1 mm of the mix is 2.25 and the Ca0/Si0 2 ratio of fine grains below 1 mm in size is 1.20:1. Therefore, a simple reduction of the Si0 2 content gives a level of [Si0 2 ]in -1 mm which is below 2.4.
  • the raw materials mix prepared in Example 3 is such that not only is the amount of silica which is added lowered but the grain size is also decreased to below 1 mm so as thereby to decrease the Si0 2 content in terms of sintered ore product down to 5.4 wt%.
  • the [Si0 2 ]in - 1 mm value is increased to 2.77 and the Ca0/Si0 2 ratio of fine grains below 1 mm in size is decreased to 0.95:1.
  • Example 4 shows in Tables s 13 and 16
  • the raw materials mix contains both return fines a part of which is crushed to a size below 1 mm and relatively course grains of other iron ores, so that the Si0 2 content in terms of sintered ore product is decreased to 5.4 wt%.
  • the mix is characterized by an [Si0 2 ] in -1 mm value which is as high as 2.97 and a Ca0/Si0 2 ratio of fine grains below 1 mm in size as high as 1.25:1.
  • Example 5 the raw materials mix is such that not only is the amount of silica added decreased to 0.8 wt% but also the grain size is decreased to below 1 mm and also it incorporates partially crushed iron ores containing a higher proportion of Si0 2 than for the mix as a whole, so that the Si0 2 content in terms of sintered ore is decreased to 5.0 wt%.
  • the [Si0 2 ]in - 1 mm of the mix is 2.55 and the Ca0/Si0 2 ratio of fine grain below 1 mm in size is 1.12:1.
  • Table 18 The results obtained by sintering the raw material mixes prepared in Comparative Example 2 and Examples 3 to 5, respectively, are shown in Table 18 and illustrated in the graph of FIG. 7.
  • the raw material mix of Comparative Example 2 which was prepared by simply reducing the SiO 2 content, provided a sintered ore having an excessively high RDI value which could only be produced after an extended sintering period and in a low sinter to sinter cake rato.
  • the mix consumed a large amount of coke as it was sintered.
  • Example 3 which was prepared by not only decreasing the amount of silica added but also by reducing its grain size to below 1 mm, provided a sintered ore having a desired RDI value (below 40), which could be produced with high productivity and in a short sintering period, consuming less coke, although the sintered ore product contained 5.4 wt% of SiO 2 which was less than the ordinary values between 5.6 and 6.0 wt%.
  • Example 4 The raw materials mix of Example 4, which contained return fines with somewhat more SiO 2 than the intended sintered one product and part of which was crushed to a size below 1 mm, provided a sintered ore having a high shatter index and an RDI value below 40. Such ore could be produced in a high sinter to sinter cake ratio, consuming a small amount of coke.
  • Example 5 prepared by not only decreasing the amount of silica added to 0.8 wt% but also by reducing its grain size to below I mm and by incorporating partially crushed iron ores which were relatively high in SiO 2 content, provided a sintered ore having a desired value of RDI below 40 without sacrificing the productivity and sinter to sinter cake ratio and without increasing the coke consumption, although the resulting sintered ore had its SiO 2 content decreased to 5.0 wt%.
  • the raw materials mix prepared in Comparative Example 3 is such that the amount of silica containing at least 90% of SiO 2 is simply decreased to lower the SiO 2 content in terms of sintered ore product from the ordinary range of 5.6 to 6.0 wt% down to 5. 4 wt%.
  • the level of [SiO 2 - Al 2 O 3 ] in -1 mm of the mix is 1.64 and the weight ratio of CaO/(SiO 2 - Al 2 O 3 ) of fine grains below 1 mm in size is 1.34:1. Therefore, a simple decrease in the SiO 2 content gives a level of [SiO 2 - Al 2 O 3 ] in -1 mm which is below 1.8.
  • the raw materials mix prepared in Example 6 contains both return fines, part of which is crushed to a size below 1 mm, and relatively coarse grains of other ores so that the SiO 2 content in terms of sintered ore product is decreased to 5.4 wt%.
  • the mix is characterized by an [SiO 2 - Al 2 O 3 ] in -1 mm value which is as high as 2.03 and a weight ratio of CaO/(SiO 2 - Al 2 O 3 ) of fine grains below 1 mm in size which is as high as 1.83:1.
  • Example 7 illustrated in Tables 23 and 26 the raw materials mix is such that not only is the amount of silica added decreased to 0.7 wt% but also its grain size is lowered to below 1 mm and further it incorporates partially crushed iron ores containing a higher proportion of SiO 2 than for the mix as a whole, so that the SiO 2 content in terms of sintered ore is decreased to 5.0 wt%.
  • the [SiO 2 - Al 2 O 3 ] in -1 mm of the mix is 1.83 and the weight ratio of CaO/(SiO 2 - Al 2 O 3 ) of fine grains below 1 mm in size is 1.29:1.
  • the process of this invention is comparable with, or even superior to, the conventional sintering technique with respect to productivity, coke consumption, shatter index and other factors, while it can lower the SiO 2 content of the sintered ore to below 5.4 wt% and decrease the slag content (SiO 2 plus CaO) of the ore without greatly increasing the level of RDI. Accordingly, the process can greatly curtail the amount of slag charged into a blast furnace, yielding an appreciable decrease in the blast furnace fuel consumption.

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EP19800300299 1979-02-01 1980-02-01 Mélange de matières premières et procédé de fabrication de minerais auto-fusibles frittés Expired EP0015085B1 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
JP967979A JPS55104439A (en) 1979-02-01 1979-02-01 Manufacture of sintered ore
JP9679/79 1979-02-01
JP59308/79 1979-05-15
JP5930879A JPS55152134A (en) 1979-05-15 1979-05-15 Preparation of low slag sintered ore
JP6284779A JPS55154535A (en) 1979-05-22 1979-05-22 Manufacture of low slag sintered ore
JP62847/79 1979-05-22

Publications (2)

Publication Number Publication Date
EP0015085A1 true EP0015085A1 (fr) 1980-09-03
EP0015085B1 EP0015085B1 (fr) 1983-01-26

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EP (1) EP0015085B1 (fr)
DE (1) DE3061710D1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007029342A1 (fr) * 2005-09-08 2007-03-15 Jfe Steel Corporation Minerai aggloméré traité thermiquement pour la fabrication de fer et procédé servant à produire celui-ci

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3519386A (en) * 1965-11-23 1970-07-07 Republic Steel Corp Process for producing a dicalcium ferrite sintered product

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3519386A (en) * 1965-11-23 1970-07-07 Republic Steel Corp Process for producing a dicalcium ferrite sintered product

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
AUFBEREITUNGS-TECHNIK, Nr. 12, 1975 Wiesbaden. O. BURGHARDT et al. "Qualitatsmerkmale von Sinter unter Beeinflussung der verschiedenen basischen Zuschlage" pages 631 to 634 *
GMELIN-DURRER "Metallurgie des Eisens" 4th edition, Vol. 1a 1964, VERLAG CHEMIE, Weinheim. pages 425a to 447a *
PATENTS ABSTRACTS OF JAPAN, Vol. 3, No. 91, 3 August 1979, page 146C54 & JP-A-54 071004 *
STAHL UND EISEN, Vol. 81, No. 1, 1961 Dusseldorf. L.V. BOGDANDY "Herstellung und Verarbeitung von Erzsinter mit hoheren Basengraden im Hochofen" pages 12 to 22 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007029342A1 (fr) * 2005-09-08 2007-03-15 Jfe Steel Corporation Minerai aggloméré traité thermiquement pour la fabrication de fer et procédé servant à produire celui-ci

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DE3061710D1 (en) 1983-03-03
EP0015085B1 (fr) 1983-01-26

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