JP4946007B2 - Manufacturing method of ferro-coke for metallurgy - Google Patents

Description

  The present invention relates to sintered ore and coke used as main raw materials for blast furnaces and the like, and more particularly to a method for producing ferro-coke for metallurgy produced from coal and iron ore.

  Sinter ore, which is the main raw material of a blast furnace, is generally manufactured as follows. First, powdered iron ore is mixed with calcium oxide-containing auxiliary raw materials such as lime powder, silicon oxide-containing auxiliary raw materials such as silica and serpentine, and carbonaceous materials such as coke powder. Grain. This granulated compounded raw material (sintered raw material) is filled onto a pallet of a Dwytroid type sintering machine to a predetermined thickness, and after igniting the carbonaceous material on the surface of the packed bed, air is directed downward. The carbonaceous material inside the packed bed is burned while being sucked, and the blended raw material is sintered by the combustion heat to obtain a sintered cake. Then, by pulverizing and sizing the sintered cake, a product sintered ore having a particle size of several mm or more can be obtained.

  In order to perform stable blast furnace operation, high-quality sintered ore is required. In general, the quality of sintered ore is measured by using shutter strength (cold strength), reduced powder index (RDI), reducibility (RI), etc. It has a great influence on the stability of the state of unloading in the furnace during blast furnace operation, air permeability and liquid permeability in the furnace, ore reduction efficiency, high temperature properties, and the like. For this reason, strict quality control is performed in the manufacturing process of sintered ore. Moreover, in order to reduce the manufacturing cost of a sintered ore, the improvement of the product yield of a sintered ore is calculated | required, and also the efficiency improvement and the improvement of a production rate of a sintered ore production line are calculated | required.

By the way, as raw material iron ore of sintered ore, hematite ore (hematite) and magnetite ore (magnetite) have been conventionally used, but the supply of such high-quality iron ore is decreasing recently. Along with this, it is necessary to use iron ore with a high phosphorus (P) content such as high phosphorus ore, and the amount of use is expected to increase in the future. Here, the high phosphorus ore is an iron ore that has a high P content compared to ordinary fine iron ore used as a sintering raw material, and generally contains 0.08 mass% or more of P (for example, (Refer nonpatent literature 1.).
146, 147th Nishiyama Memorial Technology Lecture “Recent Progress and Future of Steelmaking Technology” 1993, p. 36, 37

  The use of iron ore with a high P content such as high phosphorus ore as a blast furnace raw material increases the P concentration of the hot metal to be produced and increases the load of dephosphorization treatment. It wasn't. However, since the supply amount of high-quality iron ore is decreasing as described above, it is being studied to add a considerable amount of this high phosphorus ore as a sintering raw material. However, when the present inventors examined, although the composition of various ores is shown in Table 1, as can be seen from Table 1, high phosphorus ore (A) contains alumina compared to other ores (B to G). It is high and has a high proportion of fine powder. For this reason, the air permeability during sintering is greatly deteriorated, the production rate and yield of the sintered ore are deteriorated, the quality of the sintered ore is lowered, and it is unsuitable for the sintering operation. However, the use of high-phosphorus ore is inevitable as high-grade ore raw materials are depleted and the cost of ore raw materials is high.

  Accordingly, an object of the present invention is to solve such problems of the prior art and provide a method capable of using high phosphorus ore as a raw material for metallurgy without reducing the productivity and quality of sintered ore.

The features of the present invention for solving such problems are as follows.
(1) Coal and iron ore are mixed, and when the mixed mixture is subjected to dry distillation to produce ferrocoke, a part or all of the iron ore contains phosphorus in an amount of 0.08 mass% or more. The manufacturing method of the ferro-coke for metallurgical metal characterized by comprising.
(2) The method for producing ferro-coke for metallurgy according to (1), wherein a ferro-coke is produced by dry distillation after molding a mixture of coal and iron ore.
(3) When producing a ferro-coke by dry distillation of a mixture of coal and iron ore, the mixture contains 3% by mass to 30% by mass of high phosphorus ore (1) or (2 ) The manufacturing method of the ferro-coke for metallurgy described in.

  According to the present invention, ferro-coke can be produced as a raw material for metallurgical production using high-phosphorus ore as a raw material for ferro-coke, so that the amount of high-phosphorus ore used as a raw material for sintered ore can be greatly reduced. Reduces the productivity and quality of the ore. Moreover, high strength ferro-coke can be produced.

  In the present invention, ferro-coke for metallurgy is used as a raw material for high-phosphorus ore in order to increase the amount of high-phosphorus ore used as a raw material, without using high-phosphorus ore as a raw material for sintered ore. To manufacture.

  Ferro-coke obtained by mixing coal and iron ore and dry distillation is a porous material in which coal particles and iron ore particles are combined by a softened melt of coal, and is used as metallurgical coke. Similar to normal coke, the adhesion of the particles determines the strength of the product.

FIG. 1 shows the relationship between the mass ratio of phosphorus contained in coal and coke strength when the coal is dry-distilled. The coke strength was measured using a drum tester, and a 150 rotation 15 mm index (DI150 / 15) was used. In FIG. 1, coal having an average maximum reflectance (R ₀ ) of 0.7% is indicated by a black circle, and coal having an average maximum reflectance of 1.2% is indicated by a white circle. For coals with the same average maximum reflectivity, the maximum fluidity and total inert amount other than the average maximum reflectivity are almost equal. Therefore, although the coke strength produced is considered to be unchanged, even in coal with the same average maximum reflectivity, a difference in coke strength was observed, which had a strong correlation with the mass ratio of phosphorus. This is presumably because the phosphorus compound affects the softening and melting process of coal. That is, it is presumed that the phosphorus compound promoted the development of the laminated structure or network structure of coal during the softening and melting process of coal.

  FIG. 2 shows the coke strength when a ferro-coke is produced by blending 30% by mass of a mixture of ore A and ore F (high phosphorus ore + mara manba ore) shown in Table 1 into ordinary blended coal, followed by dry distillation. As shown in Table 1, the composition of the ore F is substantially the same as the ore A, which is a high phosphorus ore, except for the phosphorus content. The horizontal axis of FIG. 2 is the addition rate of ore A in the mixture of ore A and ore F, and corresponds to the addition rate of high phosphorus ore. A high phosphorus ore addition rate of 0 mass% means that ore F is blended by 30 mass%, and a high phosphorus ore addition rate of 30 mass% means that ore A is blended by 30 mass% of the whole and ore F is not blended. Means that. The particle size of the ore is adjusted to 0.1 mm or less (-0.1 mm 100 mass%), and the coal grade is mixed with an average maximum reflectance of 1.1%, a maximum fluidity (MF) of 1000 ddpm, and a total inert amount of 31 vol%. Then, ferro coke was produced by dry distillation. The strength was evaluated by a 15 mm index (DI150 / 15) of 150 drum rotations. According to FIG. 2, it can be seen that the strength of ferrocoke increases as the high phosphorus ore addition rate increases. From this, it is speculated that the development of the laminated structure or network structure of coal is promoted by the phosphorus compound in the ore as well as the phosphorus compound in the coal.

FIG. 3 shows the briquette strength of ferro-coke after dry distillation of a briquette formed by blending 30% by mass of a mixture of ore A and ore F shown in Table 1 (high phosphorus ore + maramanba ore) into normal blended coal, The relationship of the high phosphorus ore addition rate similar to the above is shown. The ore particle size is adjusted to 0.1 mm or less (−0.1 mm 100 mass%), and the coal grade has an average maximum reflectance of 0.7%, a maximum fluidity (MF) of 30 ddpm, and a total inert amount of 35 vol%. The briquette was molded into a 18 cm ³ pillow type using a briquette machine. The briquette strength was evaluated by a 15 mm index (DI150 / 15) of 150 drum rotations, and judged to be good if it was 81.5 points or more. Since it is briquetted and consolidated, the phosphorus concentration addition effect is slightly smaller than in the case of FIG. 2, but the briquette strength monotonously increases until the high phosphorus ore addition rate is 15 mass%. Although the effect tends to be slightly saturated at 15 mass% or more, the target strength is maintained even when the addition rate is 30 mass%. Although the briquette strength increases due to the addition effect of phosphorus, excessive addition may cause many defects in the briquette due to the reduction reaction of carbon and ore during briquetting carbonization, and there is a high concentration of phosphorus in the raw material Then, considering that the steelmaking process is hindered, when coal and iron ore are mixed, the mixed mixture is subjected to dry distillation after molding to produce ferrocoke, and the addition rate of high phosphorus ore in the mixture is 3 mass. % Or more and 30 mass% or less is considered appropriate.

  As described above, adjust the mass ratio of phosphorus in the ferro-coke raw material composed of high phosphorus ore and coal by adjusting the mass ratio of phosphorus in coal for high phosphorus ores with a high mass ratio of phosphorus. For example, it is possible to increase the amount of high-phosphorus ore while increasing the strength of ferro-coke. Therefore, by reducing the amount of high phosphorus ore used as a sintering raw material and using it as a ferrocoke raw material, high phosphorus ore is effective as a raw material for metallurgy without reducing the productivity and quality of the sintered ore. Can be used.

The graph which shows the relationship between the mass ratio of the phosphorus contained in coal, and the coke intensity | strength when the coal is carbonized. The graph which shows the relationship between a high phosphorus ore addition rate and ferro-coke strength. The graph which shows the relationship between the high phosphorus ore addition rate and briquette strength of ferro-coke.

Claims (3)

  Coal and iron ore are mixed, and when the mixture is dry-distilled to produce ferro-coke, a part or all of the iron ore is composed of high-phosphorus ore containing 0.08 mass% or more of phosphorus. A method for producing ferro-coke for metallurgy characterized by the following.   The method for producing ferro-coke for metallurgy according to claim 1, wherein a ferro-coke is produced by dry distillation after molding a mixture of coal and iron ore. 3. When producing a ferro-coke by dry distillation of a mixture of coal and iron ore, the mixture contains 3% by mass to 30% by mass of high phosphorus ore. Of manufacturing ferro-coke for metallurgy.

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