JPH11310812A - Environment-harmonized smelting reduction method using waste plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce CO2 exhausting quantity with a smelting reduction method. SOLUTION: As carbonaceous material, waste plastics 22 is used. The charge of the waste plastics is executed by controlling vertically downward momentum of the charging material per one charging chute 61 while feeding the waste plastics with carrier gas of nitrogen 8, etc., from the position of >=2 m high above the surface of molten slag 37a and the position at >=1000 deg.C atmospheric gas temp. In the case of charging with the gravity dropping, too, the momentum is regulated to >=100 kgm/s. The CO2 exhausting quantity is reduced and also, the generating quantity of SOx is reduced in comparison with the case of using the waste plastics simply as fuel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a smelting reduction smelting method for effectively utilizing resources and contributing to environmental improvement in the smelting reduction smelting method.

[0002]

2. Description of the Related Art At present, hot metal is mainly produced by a blast furnace iron making method. However, in the blast furnace iron making method, the operation of a coke oven and a sintering machine is indispensable, and its environmental conditions are severely restricted. In the future, it is expected that there will be a shortage of resources of coking coal, and that from a global perspective, iron sources and scrap are unevenly distributed. Therefore, a hot metal production process in which steam coal and fine iron ore are directly used and a preliminary reduction furnace and an iron bath type smelting reduction furnace are directly connected, that is, a smelting reduction iron making method is being studied. As a typical process of the smelting reduction iron making method, a DIOS method (Direct Iron Ore Smelting Red) is used.
uction Process). The basic principle of this method is to obtain hot metal by subjecting a carbon material to secondary combustion with an oxygen-containing gas and continuously smelting and reducing iron ore with the heat.

[0003] The problems to be solved in the smelting reduction steelmaking method are wide-ranging, but when introducing the smelting reduction steelmaking method to a number of steel mills other than the so-called integrated pig steel maker, that is, from a blast furnace facility to a rolling mill, that is, a mini mill. Therefore, there is a need for a smelting reduction process that reduces the consumption of oxygen required for smelting reduction smelting of iron ore and the amount of gas generated therefrom, and inexpensive equipment costs. Furthermore, from the viewpoint of environmental harmony in the smelting reduction steelmaking method, according to the state of the art, it cannot be said that the amount of generated carbon dioxide gas is almost the same as that of the blast furnace ironmaking method, and in some cases, there is no concern that it will increase. Moreover, even if it can be reduced, it is thought that it will be about 5% at most compared with the blast furnace iron making method. That is, as long as coal is used as the main reducing agent and fuel in the smelting reduction steelmaking method, a significant reduction in the amount of carbon dioxide gas generated cannot be expected.

Regarding the DIOS method, for example, “Recent Trend of New Iron Sources” (Iron Process Forum of the Iron and Steel Institute of Japan,
Sep. 29, 1996, pp. 42-51) (hereinafter referred to as “prior art 1”). FIG.
FIG. 1 is a schematic flow chart of equipment of a smelting reduction iron making method according to the invention.

According to this, after the ore 11 is introduced into the preheating furnace 3, it is preheated to 700 to 800 ° C. in the prereduction furnace 2,
The ore 13 preliminarily reduced to about 20% is charged into the smelting reduction furnace 1 together with the coal 21 and the slag material 26. In the smelting reduction furnace 1, the coal 21 charged as fuel and reducing material
Burns with the oxygen gas 46 blown from above to melt and reduce the preliminary reduced ore 13. Nitrogen gas 48 is blown from the lower part for bath stirring to promote the smelting reduction reaction. In the smelting reduction furnace 1, unburned CO of the CO generated by the combustion of the coal 21 is introduced from the bottom into the fluidized bed type pre-reduction furnace 2 through a cyclone, and is supplied to the pre-reduction furnace 2.
It is used to reduce the preheated iron ore 12.

In the above process, since the fluidized bed is used as a pre-reduction furnace, the iron ore charged therein has a particle size of
There is no problem of deterioration in air permeability as in a shaft furnace, and there is an advantage that a so-called sinter feed in the form of small or powdered iron ore having a particle size of about 8 mm or less can be used. On the other hand, since the process is a combination with a secondary combustion type smelting reduction furnace, the ultimate reduction rate of iron ore cannot thermodynamically exceed 33%. On the other hand, the coal can be operated according to the calorific value of the coal and its volatile matter content, so that the unit consumption of coal is about 700 to 1200 kg / t, the unit consumption of oxygen is 500 to 900 Nm ³ / t, and the sensible heat and latent heat of the generated gas. Is 1 to 5 Gcal / t. As a result, the amount of carbon dioxide generated was 550 k in the coke ratio in the blast furnace iron making method.
The level is not much different from the case of the operation at around g / t.

[0007]

SUMMARY OF THE INVENTION As described above, DIOS
The smelting reduction steelmaking method represented by the method is an excellent process in that the flexibility of raw materials and fuels is large. However, the amount of carbon dioxide generated from the process is not significantly reduced as compared with the blast furnace iron making method. Accordingly, the present inventors have studied the development of a smelting reduction method in which equipment costs and operating costs are low and the amount of generated carbon dioxide can be significantly reduced.

[0008] At that time, as a viewpoint of the study, it is added that the heat generation amount is high and the cost is low as compared with coal. Next, as the carbon material in the smelting reduction smelting method, one that can be used as at least a part of coal was selected. As a result, it was concluded that the waste plastic can meet the development purpose of the present inventors. That is, waste plastic has a higher calorific value than coal, and the composition has a smaller carbon: hydrogen ratio. Therefore, if it can be effectively used as a carbon material in the smelting reduction smelting method, it will be useful as a method of utilizing resources of wastes, and will greatly contribute to a reduction in the amount of carbon dioxide generated. However, it was concluded that in order to use a large amount of waste plastic as a carbon substitute for coal in this process, it is more desirable to solve the following problems or problems.

[0009] Waste plastic generated as social waste and household waste is generated from home appliances, various parts of automobiles, containers for household goods, containers for beverages and foodstuffs, various packaging supplies, and a wide variety of other products. The form includes a solid substance, a film-like substance, and the like, and the size, shape, weight, and the like also vary. In addition, residues of metals, ceramics, chemicals and foods are mixed. Therefore,
Separation work after collection is costly and has sanitary problems. A utilization technique that solves such a problem is desirable.

In the smelting reduction furnace, the flow velocity is usually 2-3 m
Since a rising flow of high-temperature gas of about / s was formed, it was confirmed that a method of adding waste plastic into a slag bath using a carrier gas when charging waste plastic into a smelting reduction furnace was appropriate. . Therefore, even if there is such an upward flow, the waste plastic must be lowered so as to enter the slag bath with good yield.

[0011] As described above, if the tip of the charging chute for sending waste plastic with the carrier gas is too close to the slag bath surface, the tip of the charging chute is clogged due to the splash and adhesion of splash, and continuation of operation is not possible. It becomes possible. In the equipment of the smelting reduction smelting method as exemplified in FIG. 5, high-temperature reducing gas generated in the smelting reduction furnace is supplied to a fluidized bed type pre-reduction furnace and used for pre-reduction of fine ore. Therefore, since the pre-reduction furnace is a pressurized closed furnace type, clogging of the feed system of raw fuel and the like to the smelting reduction furnace must be particularly avoided in order to perform stable and continuous operation.

Although it is a waste plastic hydrocarbon-based substance, if the temperature is not sufficiently high, the decomposition is insufficient and tar and other harmful substances for operation are generated. Tar, for example, can block piping or accumulate in the drain and clog it.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and to use a large amount of waste plastics instead of coal to further reduce the amount of carbon dioxide emitted. Is to provide a law.

[0014]

SUMMARY OF THE INVENTION From the above-mentioned viewpoints, the present inventors have conducted studies to develop an environmentally friendly smelting reduction smelting method using waste plastic as a carbon material. As a result, the following findings were obtained.

When the waste plastic is charged into the smelting reduction furnace, a raw material containing valuable metal elements such as dust ore or dust generated in a steel mill or other smelters is mixed with a lime using a carrier gas. It is possible to supply the waste plastic into the slag bath in the furnace by continuously sending the waste plastic from a predetermined charging chute into the smelting reduction furnace together with the slag-making material. Further, needless to say, the waste plastic may be mixed and molded together with the raw fuel and the slag-making material and then charged. Further, if the pre-heating and pre-reduction treatment is applied to this, it is further useful to reduce the unit fuel consumption. Further, the raw fuel and the slag-making material may be charged in a different chute form from a charging chute. For example, it may be charged in a state of being mixed with a fibrous substance, a network substance, an adhesive substance, an adhesive substance, or the like.

The present invention has been made based on the above findings, and the gist of the present invention is as follows.
The smelting reduction smelting method according to claim 1, wherein a raw material containing a metal oxide and / or a metal hydroxide and a slag-making material are charged into a smelting reduction furnace, and a carbon material containing coal and / or coke is produced. In the method of heating and melting the raw material and the slag making material by heat generated by burning the carbon material with an oxygen-containing gas, using the carbon material as a fuel and a reducing material, and directly melting and refining in the smelting reduction furnace, The material is characterized in that waste plastic is used in place of at least part of the coal and / or coke as the material and the operation is performed.

The smelting reduction smelting method according to claim 2 is the method according to claim 1, wherein the waste plastic is charged into a smelting reduction furnace as described in (a), (b) and (c) below. It is characterized by satisfying the conditions described above.
Here, the conditions (a), (b) and (c) are (a)
Waste plastic should be charged from a position at least 2 m above the surface of the slag bath in the smelting reduction furnace.
From a location in the atmosphere that is at least ℃, and
(C) The input of the waste plastic is performed by sending out the carrier gas from the input chute, and the waste plastic (P) charged per input chute, and
The vertical downward momentum of the total solid substance (P + Q + R + S) of carbon material (Q), raw material (R) and slag-making material (S) other than the waste plastic sent out along with the waste plastic is 100 kgm / s. It means to operate as described above.

In the above, the raw materials containing metal oxides and / or metal hydroxides include ores, dusts containing metal elements generated in steelworks and other smelters, direct reduced iron (DRI), hot metal Briquette Iron (HBI),
Any of reduced pellets, semi-reduced pellets, unreduced pellets, and wastes containing iron or other metal elements of various metals may be used, and these all have similar functions and effects as raw materials.

[0019]

Next, the present invention will be described with reference to the drawings. A feature of the present invention is particularly that of a smelting method in a molten metal bath type smelting reduction furnace in a smelting reduction smelting method of fine ore. FIG. 1 is a schematic flow chart of equipment showing one embodiment of the present invention. A coarse pre-reduction ore 13a discharged from the fluidized bed pre-reduction furnace 2; a fine pre-reduction ore 13b generated in the pre-reduction furnace 2 and the smelting reduction furnace 1 and recovered by a cyclone (not shown); A part of the waste plastic 22 as the carbon material, 100% of the remainder of the coal 21 or 100% of the waste plastic 22, and the slag-making material 26 are charged into the furnace from a charging chute provided at the upper part of the smelting reduction furnace 1. .

FIG. 2 shows a conceptual diagram of a main part of the smelting reduction furnace of FIG. Here, coarse and fine ores (13a
In addition to 13b), a metal-containing element-containing substance such as a metal-element-containing dust generated in a steel mill or another smelter may be appropriately mixed and charged. In addition, as a carbon material, oil coke and other carbon-containing substances may be appropriately mixed and charged. The charging of the raw material, the carbonaceous material, and the slag-making material is performed by sending the charged material 63 in the form of a collective flow using a carrier gas, for example, a nitrogen gas 8 from the tip of the charging chute 61 downward. Further, the timing of the charging is continuously performed. However, depending on equipment conditions and the like, it may be charged from the charging chute 61 by a gravity drop method. In this case, a purge gas is supplied to prevent clogging of the charging chute. On the other hand, oxygen gas 46 is blown upward from the lance 62 into the furnace, and bath stirring gas, for example, nitrogen gas 48, is blown from the bottom of the furnace. The ore charged in the smelting reduction furnace 1 is melted by the heat of combustion of the carbonaceous material, enters the slag bath 37a, is reduced by carbon, and moves to the molten metal bath 36a.

As described above, when waste plastic is used as a carbon material instead of coal or coal and coke for part or all, the following effects are exhibited. The calorific value of waste plastic is about 8400 kcal / kg, about 7000 to 7700 kcal / kg of coal, and about 70 kcal / kg of coke.
Since it is much larger than 00 kcal / kg, the carbon unit and oxygen unit required for smelting are reduced, and the amount of carbon dioxide generated from the smelting reduction smelting process system is greatly reduced. Therefore, the use of waste plastic as a substitute for coal or coke is desirable in terms of contributing to environmental conservation and improving the production efficiency and thermal efficiency of the process.

It is necessary that the above-mentioned effects be sufficiently exhibited and that the actual operation be well established as a method for producing molten metal. From this point of view, waste plastic soars with the hot air in the furnace and is not taken out of the smelting reduction reaction system as much as possible, it is added to the slag bath, and continuous operation of the whole system of the smelting reduction process which is a closed system Therefore, it is important not to cause troubles such as a closing chute and a blockage of a piping system.

In view of the above, in the present invention, the method of charging the waste plastic is limited as described above. The grounds and the effect in such a case will be described. (1) The waste plastic is charged from a position at least 2 m above the surface of the slag bath in the smelting reduction furnace.

Based on experience in the actual operation of a smelting reduction furnace, the present inventors have proposed a method in which waste plastic is fed from a charging chute shown in FIG. 2 together with other charges by a carrier gas. Unless the tip of the chute is placed at a height of at least 2 m away from the slag surface in the furnace, it is clarified that blockage of the tip of the chute due to adhesion of molten slag droplets becomes a problem. More desirably, the distance is more preferably 3 m or more, and if it is more than 5 m, no problem occurs.

(2) The waste plastic is charged from a position in the atmosphere where the atmosphere gas in the furnace is 1000 ° C. or higher. When the waste plastic is charged into the smelting reduction furnace, it is divided into a part that decomposes and gasifies, a part that liquefies, and a part that remains in a solid state. When the waste plastic is charged with the carrier gas together with the other charges, the tip of the charging chute is at least 2 m higher than the slag surface, and the tip position is 1
If the temperature was not higher than 000 ° C., hydrocarbons in the waste plastic were not sufficiently decomposed, and generation of tar and other substances harmful to the operation was recognized. In this case, since there is a problem in the environment, it is desirable to load the waste plastic from a high-temperature atmosphere region of 1000 ° C. or more.

(3) The waste plastic is fed by a carrier gas from a charging chute, and the waste plastic (P) charged per charging chute and the waste plastic are sent out along with the waste plastic. , A solid material (P + Q + R +) composed of the carbon material (Q) other than the waste plastic, the raw material (R), and the slag-making material (S).
The operating conditions are adjusted so that the vertical downward momentum in S) is 100 kgm / s or more. In addition, if the vertical downward momentum of all the solid substances is set to be 100 kgm / s or more, the solid substances may be charged from a charging chute by a gravity drop method.

The form of the waste plastic is as described above.
Solids and films, large and small in size and weight, impurities such as metals, ceramics, contaminants such as residual foods, etc.
It is very different from general coal particles. Usually, the gas superficial velocity in the smelting reduction furnace is about 2 to 3 m / s, and the waste plastic easily flows out of the furnace by this gas flow regardless of the form of transfer. The present inventors have sent waste plastics vertically downward into the furnace with a carrier gas together with other charged substances from a charging chute and grasped the flow of all charged substances as a collective motion. Then, focusing on the vertical downward momentum of the entire charge, the effect of the above momentum on the scattering loss of the waste plastic was tested.

FIG. 3 shows the effect of the vertically downward momentum of the whole charge on the scattering loss ratio of the waste plastic, and the relationship between the scattering loss and the gas superficial velocity in the furnace. As can be seen from this result, in order to suppress the scattering loss of the waste plastic to 2 to 3% or less, from the input chute, together with the other charges, a state of collective flow is carried out with the carrier gas, and the entire charge is taken. This is achieved by adjusting the vertical downward momentum of the object to 100 kgm / s or more.

Another advantage of using a waste plastic as a substitute for coal as a carbon material in a smelting reduction furnace will be described. The form of the waste plastic is not particularly limited as long as its size can be cut out from the hopper through the intermediate hopper without problems from the input chute. Fe in the contaminants is useful because it is used as an iron source material, and Zn and Sn
Metals with a high vapor pressure, such as, are removed from the dust without mixing into the hot metal, so they are separately treated by a conventional method. Metals that are easily oxidized, such as Cr, migrate to slag with a high oxygen potential, and ceramics also migrate to slag, so there is no particular problem. However, metals that are difficult to oxidize, such as Cu, enter into the hot metal, so that those that are mixed in large quantities should be sorted out. This is advantageous because most waste plastics require little pre-treatment.

The S content of the waste plastic is about 0.1 wt.%
It is smaller than about 0.5 wt.% Of coal, and the greater the substitution amount by waste plastic, the more the load of molten metal desulfurization is reduced, which is advantageous. Now, carbon materials, including waste plastic,
Total amount of sulfur brought into the furnace from the entire raw material and slag-making material (hereinafter referred to as "input total sulfur"), slag (FeO) concentration, slopping state (index), and metal [C] concentration FIG. 4 shows the relationship between the concentration and the [S] concentration in the metal. Normally, as shown in FIG. 4, when the total sulfur input increases, the [S] concentration in the metal increases, which impairs the carburizing effect on the metal due to the addition of the carbonaceous material, and sufficiently increases the carbon concentration in the metal. Absent. As a result, the operation becomes unstable due to an increase in valuable metal oxides (M _X O _Y ) in the slag due to a delay in the reduction of the ore, occurrence of slopping, and the like. However, waste plastic has much lower S content than coal,
Even if a large amount of waste plastic is used, such operation is not unstable, and stable operation can be obtained.

Further, the moisture content in the waste plastic is about 2 wt.%, And the moisture content is considerably lower than that of about 10 wt.% Of coal, so that it is not necessary to separately perform moisture drying.
Since the S content is low, SO _X generated when waste plastic is used as mere fuel or when incinerated is small, and most of the SO _X is transferred to slag and hot metal and fixed. There is an advantage that emission to the atmosphere can be avoided.

[0032]

Next, the smelting reduction smelting method of the present invention will be described in more detail with reference to examples. As Examples 1 to 10,
FIG. 4 shows a case where hot metal was manufactured by continuous operation by a method within the scope of the present invention using the smelting reduction steelmaking equipment with a hot metal production rate of 500 t / d shown in FIGS. 1 and 2 and Comparative Examples 1 and 2. In addition, a test was conducted for a case where hot metal was produced by continuous operation by a method outside the scope of the present invention using a smelting reduction facility similar to the facility used in the examples at a hot metal production rate of 500 t / d.

Table 1 shows the analysis results of the iron ore used, and Table 2 shows the analysis results of the waste plastic used. For waste plastic, 10,000 kcal / kg of polyethylene or the like called virgin pellets
High-calorie, low-ash, high-quality products, but crushed products, wind-selected materials, magnetic cards, etc.
Even very low-calorie resin-based substances of about 00 kcal / kg are contained, and fluctuations in particle size and components are inevitable. However, if you look at the average of what you can get,
As shown in Table 2. Thus, the calorific value is not so high as compared with coal, but the sulfur content is at a very low level.

[0034] Waste plastic is
In addition, since the water content is low, it is not always necessary to take measures such as pneumatic feeding and blowing for transport in the smelting reduction steelmaking process system and charging to the smelting reduction furnace. There is no particular problem in use as long as the pipe diameter is such that the pipe system up to the charging chute in the smelting reduction furnace is not clogged, and the number is usually 1/3 or less of the diameter of 100 mm. Also, it is noted that there is no problem in use even if foreign substances such as metals and ceramics are mixed and adhered.

[0035]

[Table 1]

[0036]

[Table 2]

(1) Test conditions of the examples The test conditions of the examples are roughly divided into 50% (Examples 1 to 4) and 60%
(Example 9) and 100% (Examples 5 to 8 and 10). Then, the following operation factors (a) to (f) were set as follows within the scope of the present invention, and a test operation was performed in a case where these were appropriately combined.

Tables 3 to 6 show the test conditions.

[0039]

[Table 3]

[0040]

[Table 4]

[0041]

[Table 5]

[0042]

[Table 6]

[Operating Factors and Their Levels] (a) Preliminary Ore Reduction Rate in Preliminary Reducing Furnace: When ore preheated and dried in a preheating furnace is used, it is reduced to about 20%, while direct prereducing furnace is used. When ore was charged, the reduction was limited to around 10%. (B) Particle size of waste plastic: From the viewpoint of reducing the scattering loss of waste plastic from the smelting reduction furnace, it is better to be large, and about 1/3 or less of the pipe diameter is necessary to prevent clogging. In addition, the smaller the degree of progress of the decomposition, gasification, and combustion of the waste plastic, the better. Here, 1 to 15
mm. (C) Secondary burning rate: The test was carried out while controlling at two levels of about 30% and 35%. (D) Height of the throwing chute from the slag bath: The higher this height is, the less the slag is scattered and adhered to the tip of the throwing chute, and the operation trouble due to the clogging is eliminated.
The test was performed by changing the range of about 2 to 5 m. (E) Atmospheric temperature at the tip of the charging chute: Determined by the height of the charging chute from the slag bath and the smelting conditions. If the temperature is too low, an operation inhibiting substance such as tar is generated. 1160
Tested within a wide range of 1330 ° C. (F) Momentum of the charge from the input chute: This is a factor that affects the amount of scattering loss of the waste plastic.
Tested at several levels over a wide range of 50-2000 kgm / s.

(2) Test Conditions of Comparative Example As the test conditions of the comparative example, as a typical process of the conventional DIOS method, the case where the ore preheating furnace was not used (Comparative Example 1) and the case where the ore preheating furnace was not used (Comparative Example 2) ) Were tested for the case where 100% of coal was used without using waste plastic as a carbon material. In Comparative Example 1, the charging method from the charging chute was performed by the gravity drop method as in the conventional carbon material charging method. In Comparative Example 2, the charge was similarly performed from the charging chute by the gravity drop method, and the height of the charging chute tip from the slag bath surface was 1.7.
m and low.

(3) Test results Tables 7 to 10 show the test results.

[0046]

[Table 7]

[0047]

[Table 8]

[0048]

[Table 9]

[0049]

[Table 10]

Calculation of Carbon Dioxide Emission In order to obtain the input C amount (A), the C amount in the carbon material, the C amount in the slag material, and the production of top-blown O ₂ gas to the smelting reduction furnace The value obtained by subtracting the converted C amount of fuel consumed for power generation in utilities other than the top-blown O ₂ gas production apparatus from the total value of the required converted C amount of fuel consumed for power generation is calculated, and this value is calculated. The input C amount (A) was used. on the other hand,
As the deduction C amount (B) from the input C amount (A), the sum of the amount of power generated by the recovered gas and each converted C amount of the amount of power generation by the recovered steam is obtained, and the deduction C amount (A) is obtained from the input C amount (A). The value obtained by subtracting B) ((A)-(B)) was represented by the amount of consumed C (C). And the consumption C amount (C) was converted into the carbon dioxide amount, and shown in Tables 7 to 10.

Comparing the embodiment and the comparative example with respect to the amount of carbon dioxide emitted, the use of waste plastic as the carbon material significantly reduces the amount of carbon dioxide emitted. And Examples 1-4 (Waste plastic ratio 50%
) And Examples 5 to 8 (waste plastic ratio 100%)
It can be seen from the comparison with the above case) that the larger the waste plastic substitution ratio in the carbonaceous material, the lower the amount of carbon dioxide emission outside the system.

Scattering loss of waste plastic from the smelting reduction furnace The scattering rate of the waste plastic is calculated from the average scattering rate of the carbon material when the proportion of the waste plastic in the carbon material in the charging material is the same. You can compare rates.
Generally, the scattering loss of waste plastic decreases as the particle diameter of waste plastic increases. The waste plastic is pumped down from the tip of the input chute in the form of a mass flow by means of a carrier gas together with the other charges. As the momentum increases, the scattering loss of the waste plastic from the smelting reduction furnace decreases. In Examples 1 to 4, the average particle size was sequentially increased from 1 to 5 mm, and the momentum was increased from 150 to 1000 kgm / s. In Examples 5 to 8, the average particle diameter was increased from 5 to 15 mm, and the momentum of
It was increased from 00 to 2000 kgm / s. The larger the average particle size and the greater the momentum, the smaller the scattering loss of the waste plastic.

When the scattering rates of the waste plastics of Examples 9 and 10 are compared with the scattering rates of the waste plastics of Examples 1 to 4 and Examples 5 to 8, the former is considerably smaller than the latter. This indicates that the momentum of the charge containing waste plastic was small in Examples 9 and 10 (50-
60 kgm / s). On the other hand, in Comparative Examples 1 and 2, coal was charged by a gravity drop method while flowing a purge gas, but the scattering rate of coal was small and good. When the momentum of the entire charge at the tip of the charging chute in this case is estimated, it is about 200 kgm / s per charging chute.

Therefore, regardless of the pneumatic method or the gravity drop method, the scattering rate of the carbonaceous material is such that the momentum of the whole charge at the tip of the charging chute is 1 per charging chute.
It can also be seen that if it is about 00 kgm / s or more, it is very small and good.

The waste plastic scattered from the smelting reduction furnace is collected by a dust collector of the smelting reduction furnace, collected and reused. Therefore, even if the scattering loss of the waste plastic increases, the carbon dioxide discharged to the outside of the smelting reduction steelmaking process system does not increase. However, if the unit consumption of waste plastic in the carbon material in the input C amount (A) is compared with the unit consumption of the carbon material in the input C amount (A) when the waste plastic ratio is the same level, As can be seen, the greater the scattered amount, the greater the scattered waste plastic waste ratio.

Influence of the height of the charging chute on the operation The higher the height of the charging chute from the slag bath surface, the less the slag adheres and accumulates at the tip. Example 1
In Example 8, the height was about 4 m or more.
Also in Examples 10 and 10, 2 m or more was secured, so that troubles such as blockage of the input chute did not occur. However, in Comparative Example 2, the height of the input chute was slightly lower,
Moreover, the charging method was the gravity drop method. Therefore, due to the attachment and accumulation of slag at the tip of the charging chute and the delay in the rate of addition of the charge to the slag bath due to this,
The (FeO) concentration in the slag was slightly increased. And the slopping index increased.

Influence of the ambient temperature at the tip of the charging chute on the operation The ambient temperature at the distal end of the charging chute was 1000 ° C. or higher in all cases of the examples and comparative examples. The generation of substances such as tar was prevented, and there was no operation trouble due to clogging of the piping system and the like.

Generated Slag Amount and Net Consumption Energy The generated slag amount is desirably smaller in the example than in the comparative example. Further, the net energy consumption is preferably smaller in Examples 1 to 8 than in Comparative Example. However, although the net energy consumption in Examples 9 and 10 is equal to or higher than the comparative example, there is no difference between the sum of the net energy consumption and the surplus energy.

Productivity The hot metal [C] concentration in Examples 1 to 8 was secured to about 4% or more, the slag (FeO) concentration was low, and the iron ore reduction rate was maintained at a high level. As for the productivity, continuous operation equal to or higher than that in the comparative example was continued without any problem, and the target level of the hot metal production rate of 500 t / d was achieved.

Prevention of SO _X generation As shown in Table 2, S contained in the waste plastic is considerably lower than that of coal. Moreover, when used in the method of the present invention, it is transferred and fixed in the hot metal and slag also through dust recovery and preheating / preliminary ore,
Almost no air emissions outside the smelting reduction steelmaking process system were observed.

The above embodiment relates to smelting reduction smelting of iron ore, but instead of iron ore, Ni, Cr or M
Similarly, the method of the present invention is also effective in the case of smelting in a smelting reduction furnace for dusts containing metals and metal oxides such as n and those metal elements in a smelting reduction furnace, and pre-reduction in a fluidized bed apparatus. is there.

[0062]

As described above, according to the present invention,
In the smelting reduction smelting method, while effectively utilizing waste plastic resources, it is possible to contribute to environmental improvement by greatly reducing the amount of carbon dioxide emitted as compared with the conventional smelting reduction smelting method. Further, the generation of SO _X generated when the waste plastic is used as a fuel is also suppressed. As described above, it is possible to provide a smelting reduction smelting method that contributes to environmental improvement by using waste plastic, and an industrially useful effect is provided.

[Brief description of the drawings]

FIG. 1 is a schematic flow chart of equipment showing one embodiment of the present invention.

FIG. 2 is a conceptual diagram of a main part of the smelting reduction furnace of FIG.

FIG. 3 is a graph showing the effect of the vertical downward momentum of all charges on the scattering loss of waste plastic from a smelting reduction furnace, and the relationship between the scattering loss and the gas superficial velocity in the furnace.

FIG. 4 is a graph showing the effect of total sulfur input to a smelting reduction furnace on hot metal [S], hot metal [C], slag (FeO) and the degree of slopping.

FIG. 5 is a schematic flow chart of equipment of a smelting reduction iron making method according to Prior Art 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Smelting reduction furnace 2 Preliminary reduction furnace 3 Ore preheating furnace 6 Slag-making material firing furnace 8 Nitrogen gas (carrier gas) 11 Raw ore 12 Preheat ore (coarse / fine) 13 Preliminary ore (coarse / fine) 14 Raw material 20 High-calorie fuel 21 Coal 22 Waste plastic 25 Slag making material 26 Slag making material 31 Generated gas 32 Generated gas 33 Generated gas 34 Collected gas 35 Collected steam 36 Molten metal 36a Molten metal bath 37 Slag 37a Slag bath 38 Collected dust 46 Oxygen 47 Air 48 Nitrogen gas (stirring gas) 49 Gas calorie adjusting fuel 51 Dust remover 52 Gas holder 53 Booster 54 Power generation equipment 56 Steam recovery boiler 57 Gas 61 Input chute 62 Lance 63 Charge

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Terutoshi Sawada 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan Inside Nihon Kokan Co., Ltd. (72) Inventor Takeshi Sekiguchi 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan (72) Inventor Masayuki Watanabe 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd.

Claims (2)

[Claims] 1. A raw material containing a metal oxide and / or a metal hydroxide and a slag-making material are charged into a smelting reduction furnace, and a carbon material containing coal and / or coke is used as a fuel and a reducing material. A method in which the raw material and the slag making material are heated and melted by heat generated by burning the carbon material with an oxygen-containing gas, and are directly subjected to smelting reduction smelting in the smelting reduction furnace; Alternatively, an environment-friendly smelting reduction smelting method characterized by using waste plastics instead of at least a part of coke for operation. 2. The environment according to claim 1, wherein the method of charging the waste plastic into the smelting reduction furnace satisfies the following conditions (a), (b) and (c). Harmonious smelting reduction smelting method. (A) The waste plastic is charged from a position at least 2 m above the surface of the slag bath in the smelting reduction furnace. (B) The waste plastic is charged from a position in the atmosphere where the atmospheric gas in the smelting reduction furnace is 1000 ° C. or higher. (C) The injection of the waste plastic is performed by sending out the carrier chute from the input chute, and the waste plastic (P) charged per one input chute and the waste plastic accompanying the waste plastic. The total solid substance (P +) to be sent out, consisting of the carbon material (Q) other than the waste plastic, the raw material (R), and the slag material (S)
Q + R + S) vertical downward momentum is 100 kgm / s
Operate in such a way.