JPH0432505A - Iron-making method with smelting reduction - Google Patents

Abstract

PURPOSE:To produce molten iron from powdery iron ore with simple process without needing expensive heavy caking coal by using compacted powdery coal as reducing agent at the time of producing the molten iron by using powdery iron ore as raw material in a top-bottom combined blowing converter type metallurgical furnace. CONSTITUTION:Into the converter type metallurgical furnace providing a top blowing lance 3 and bottom blowing tuyeres 2, the powdery iron ore as the raw material is charged from a charging hole 4 arranged at the top part of furnace and also carbonaceous material pressurizing and compacting the powdery coal is charged from opening part 7 at the upper part of furnace as the reducing agent, and O2 gas is blown from the top blowing lance 3 and also inert gas of N2 gas, etc., is blown from the bottom blowing tuyeres 2. The powdery iron ore is heated and reduced to form the molten iron and molten slag. Without needing to make bulky state by sintering the powdery iron ore and without using bulky coke made of the expensive heavy caking coal for blast furnace as the raw material, the molten iron can be produced from the powdery iron ore at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a molten iron alloy from iron ore or its pre-reduced product by melt reduction.

[Prior Art] A blast furnace method is currently used as a mass iron manufacturing method. The blast furnace method is an excellent process in terms of productivity and thermal efficiency, but the problem is that the ore requires an agglomeration process such as sintering, and the coal requires a coking process. In order to produce high-strength coke, a specific type of coal called coking coal is used.

On the other hand, the smelting reduction method is a new process that has been developed to solve the problems inherent in the current blast furnace method as described above.

As one of the smelting reduction methods, a method is being developed that uses a metallurgical furnace that can blow gas from the top and bottom and utilizes the large amount of slag that exists, and some problems have already been solved.
Only the issue of coal remained.

In other words, in order to solve the coal problem inherent in the blast furnace method, it is desired to develop a process that uses inexpensive steam coal and does not require a coking process. This problem was difficult to solve for several reasons.

First, the coal is sifted to form lumps (approximately 1011III
1 or more) and put it into a smelting reduction furnace, the volatile matter rapidly vaporizes due to rapid heating, resulting in thermal cracking and cracking into particles with an average particle size of about 3 mm. As a result, the following two problems arise.

■ The scattering rate of carbonaceous materials is 10% or more (of the carbonaceous materials, carbonaceous materials of 2III11 or less are scattered at a certain rate (for example, 15% of carbonaceous materials of 2IIIfi or less).

■ As the carbon material becomes finer, its specific surface area becomes larger, making it less likely to get caught up in the slag, which delays carburization into the metal, making stable operation impossible.

On the other hand, if powdered lime is added from above, the scattering rate will be close to 30%, and if powdered lime is blown into the metal, the agitation of the metal will become too strong as a result of the blowing, resulting in an increase in the amount of iron-based dust generated. In addition, if powdered lime is molded (for example, into briquettes) by adding a binder to it, the binder becomes a gas-generating material and breaks into small pieces because it is rapidly heated in the furnace. There are also many problems.

As described above, in the conventional method, coal pulverization is an unavoidable problem, and as a result, stable melting and reduction operations cannot be performed.

[Problem to be solved by the invention]

The present invention is based on the above findings, and aims to provide a method for producing iron that can perform stable smelting and reduction operations without pulverizing carbonaceous materials when rapidly heated in a smelting and reduction furnace. purpose.

[Means to solve the problem]

In the present invention, for example, as shown in FIG. A method for manufacturing iron alloys, the gist of which is an iron manufacturing method by smelting reduction, which is characterized by using compression-molded powdered lime without adding a binder as a carbonaceous material.

[Effect] First, Fig. 2 shows the influence of the amount of the added binder (molasses) in the case where powdered lime is mixed with a binder and molded. In general, in the case of any binder, not just molasses, the cold strength increases as the blending amount increases, but rapid heating conditions such as when put into a smelting reduction furnace actually promote powdering. I understand that. On the other hand, it is most difficult to powder when no binder is added. The definition of powder is the weight ratio under the sieve with a diameter of 2 mm or less (as mentioned above, there is a probability that some powder with a diameter of 2111 m or less will be scattered).
.

Next, Figure 3 shows the effect of the volatile content (V, M, Showing the effect of quantity. When the volatile content is 23% or more and 3
It can be seen that when it is 8% or less, the powder generation rate during rapid heating can be suppressed to a low level. This is determined by the combination of two functions: the volatile content melts during the heating process and plays the role of a binder, and on the other hand, a large amount of gas is generated which destroys the molded product.

FIG. 4 shows the relationship between the thickness of the molded product and the powder generation rate (powderization rate) during rapid heating. It can be seen that the powder generation rate can be minimized when the thickness is 3 to 81Il11.

FIG. 5 shows the relationship between the moisture content of powdered lime and the powder generation rate during rapid heating. In order to keep the powder generation rate low, the moisture content is 3%.
It can be seen that the following is desirable.

FIG. 6 shows the relationship between the molding pressure (compressive strength) by the rolls and the powder generation rate of the molded product when rapidly heated. The molding pressure to suppress powdering during rapid heating is 1 mm thick.
It can be seen that 0.3 t/af1 or more is required per unit.

FIG. 7 shows the influence of the ratio (concentration) of iron oxide added to powdered lime on the pulverization behavior when a molded product is rapidly heated. It can be seen that when the amount of iron oxide blended exceeds 10 ivt, χ, the degree of powdering increases dramatically.

Therefore, if necessary, dust can be mixed with powdered lime and molded by the method of the present invention, but in this case,
The blending amount must not exceed 10 wt (χ) as iron oxide. In addition, in the present invention, the main raw material, iron ore or its pre-reduced product, is charged into the smelting reduction furnace through a route different from that of powdered lime, so the ore does not scatter through the space and reaches the molten slag layer. Once transferred, the molten slag has the property of getting wet, so no further scattering occurs.

Powdered coal formed under the appropriate conditions as described above is difficult to turn into powder even if it is put into a smelting reduction furnace and subjected to rapid heating. It has now become possible to solve the coal problems that were considered to be problems in the development of , namely the problems of scattering and delays in metal carburization.

〔Example〕

FIG. 1 shows an example of equipment for a melting reduction furnace used to carry out the present invention. In a container lined with a refractory 1, a bottom blowing tuyere 2 is provided at the bottom for blowing a gas such as nitrogen into the molten metal to stir it. Top blow lance 3
is for supplying oxygen gas into the furnace. Ore is supplied into the furnace from a fine ore input port 4 provided in the furnace layer. There is a large amount of molten slag 5 in the furnace, and it is necessary to isolate the bottom-blown, agitated metal 6 bath from the top-blown oxygen jet. The required amount of slag is 350
kg/l metal or more, the amount of remaining metal and remaining slag is adjusted when the generated metal 6 and slag 5 are discharged by tilting the furnace.

Table 1 shows the main operating conditions of the smelting reduction furnace.

The ore used was pre-reduced ore. The component conditions are shown in Table 2. This was transported into the furnace using nitrogen gas from the fine ore input port 4 in the furnace layer of the smelting reduction furnace.

Table 2 On the other hand, carbon materials subjected to various treatments as shown in Table 3 were used in the test operation of this example. In both cases, the material was introduced into the furnace from the furnace lower.

As a result, the operational results when changing the type of carbon material were as shown in Table 4.

Therefore, favorable results were obtained according to the present invention, that is, when a molded carbonaceous material without the addition of a binder was used.

[Effects of the Invention] As described above, the present invention is a smelting and reduction process for manufacturing iron using powdered ore and general coal powder, which are the cheapest raw materials, without using an expensive binder. 2. It solves the problem of cracking during rapid heating, and has great industrial and economical effects.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing an example of the smelting reduction furnace equipment used to carry out the present invention, and Figure 2 shows how the binder blended when molding powdered coal becomes powder when the molded product is rapidly heated. Figure 3 shows the effect of the volatile content of powdered coal on the pulverization behavior when the molded product is rapidly heated. Figure 4 shows the effect of the volatile content of powdered coal on the pulverization behavior when the molded product is rapidly heated. A diagram showing the effect of the thickness of the molded product on the pulverization behavior. Figure 5 is a diagram showing the effect of the water content of powdered coal on the pulverization behavior when the molded product is rapidly heated. Fig. 7 is a diagram showing the effect of the blending ratio of iron oxide in powdered coal on the powdering behavior when a molded product is rapidly heated. It is. Fig. 2. I3 4. Figure 2. I3 4. Cohesion. Moisture content zone (% di Figure 6 Q, / 0.2 Q3 0.
4. Molding pressure (required type molding V-O,s

Claims (1)

[Claims] In a method of manufacturing a molten iron alloy by supplying oxygen gas while adding a raw material containing iron oxide and carbonaceous material to a metallurgical furnace that can blow gas from the top and bottom, and melting and reducing the iron oxide,
A method of making iron by smelting and reduction, characterized by the use of compression molded powdered coal without adding a binder as the carbon material.