JPH07258754A - Production of sintered ore - Google Patents

Abstract

PURPOSE:To evaporate away copper, tin and zinc included in iron scrap in the case of using scrap for sintered ore. CONSTITUTION:Calcium chloride is mixed at a ratio of 1 to 5 times the copper, tin and zinc equiv., by weight, included in the chips of the iron scrap into these chips. This mixture is charged to a range of a layer height <=300mm from a grate plane 11 of a sintering layer and is sintered. As a result, the sintering is executed while the copper, tin and zinc included in the iron scrap are removed and, therefore, the restriction on the amt. of the iron scrap to be used is eliminated and the mount of use is increased. The consumption unit of coke is thus lowered and NOx and SOx are decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing iron ore sintered ore by a downward air suction type sintering machine such as DL type and GW type.

[0002]

2. Description of the Related Art In DL type iron ore sintering method, recycling of iron scrap is becoming more and more important from the viewpoint of energy saving, effective use of resources, and global environmental problems. On the other hand, as described in Japanese Patent Application Laid-Open No. 52-53704 and Japanese Patent Application No. 5-283650, the technique of using iron scrap for sintering is effective. The contained zinc accumulates in the blast furnace and makes the operation of the blast furnace unstable, and tin and copper cannot be removed even in the ironmaking and steelmaking, and remain in the steel, which adversely affects the properties of the steel. Therefore, the trace metal component contained in scrap becomes a problem, and the amount of iron scrap used is limited. Therefore, there is a demand for a sintering method that can remove trace components such as copper, tin, and zinc contained in these scraps.

[0003]

[Problems to be Solved by the Invention] Copper in iron scrap,
Chlorine volatilization is a method for removing tin and zinc. It is known that the boiling point of chloride is relatively low such as zinc chloride 732 ° C. and tin chloride 623 ° C., and vaporization of trace elements can be easily volatilized because of high vapor pressure. However, the details of the optimum combination of temperature conditions and atmosphere for simultaneously volatilizing and volatilizing copper, tin, and zinc were unclear.

The present invention focuses on the above-mentioned problems,
(EN) A method of solving the problem of a trace amount of metal, which is a constraint condition for using iron scrap in the sintering of sinter, and providing a method of sintering using a large amount of iron scrap without limitation.

[0005]

The method for producing a sinter according to the present invention is a method for producing an air downward suction type sinter, wherein the weight is 1 to 5 times the equivalent of copper, tin and zinc contained in iron scrap. The ratio of calcium chloride is mixed with iron scrap, and the mixture is charged into a range of layer height 300mm or less from the great surface of the sintered layer of the downward air suction type sintering machine and sintered to be contained in the iron scrap. The method for producing a sintered ore is characterized in that copper, tin, and zinc are volatilized by volatilization and sintered while being removed. It is preferable to mix an iron scrap having a size of 15 to 150 mm with calcium chloride, and to spray or immerse a chip of the iron scrap in a slurry of calcium chloride, and then load the iron scrap into a sintering machine for sintering.

[0006]

In chloride volatilization, copper, tin, and zinc in the iron scrap can be most efficiently volatilized under a temperature of 1000 to 1400 ° C. and an oxygen partial pressure of 10 ⁻⁶ to 10 ⁻² atm. 1000
If the temperature is lower than ℃, copper remains in the solid even in a reducing atmosphere, which is not preferable. Also, the higher the temperature, the more copper, tin,
In addition to chloride volatilization and reduction volatilization of zinc, 140
If the temperature exceeds 0 ° C, volatilization of iron in the iron scrap begins, which is not preferable. Therefore, copper contained in iron scrap,
The heating temperature for removing tin and zinc is 1000 to 140.
0 ° C is preferred. Further, copper, tin, and zinc can be removed when the oxygen partial pressure is 10 ^-10 to 10 ^-2 atm in the range of 1000 to 1400 ° C, but the reduction volatilization of iron also occurs when the oxygen partial pressure is less than 10 ^-6 atm. Since it starts, the oxygen partial pressure is 10 ^-6 to 10 ^-2
atm is preferred. As for the upper limit of the oxygen partial pressure, copper can be used up to air, but tin is difficult to be volatilized and removed.
Since O ₂ ) is generated, the upper limit is 10 ⁻² atm.

According to the present invention, the atmosphere during sintering of the downward air suction type sintering machine is 1000 to 1400 ° C. and the oxygen partial pressure is 10 ⁻⁶ to.
Focusing on 10 ^-2 atm, it does not require any special equipment and burns iron scrap mixed with calcium chloride in a sintering machine so that trace metals evaporated from the iron scrap do not solidify and deposit in the lower raw material layer. Copper, tin, and zinc contained in the iron scrap can be volatilized by volatilization by simply charging the lower layer of the binder, and the treated iron scrap can be charged into the blast furnace as sinter.

The present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, calcium chloride was mixed with iron scrap in a mixer 3-1 at a weight ratio of copper, tin and zinc equivalents or more contained in the iron scrap, and then added to a raw material for sintering. DL in the lower raw material charging device 6-1
300m from the great surface 11 of the sintered layer of the rotary sintering machine 8
The upper raw material charging device 6-
2 are piled up and charged into the upper layer of the sintered layer. The charged raw material is ignited in the ignition furnace 7, and is sequentially sintered from the surface layer to the lower layer, but after passing through the ignition furnace 7, the sintering is completed from the upper layer of the sintering bed as the strand progresses, Caking and cooling gives a sinter cake. Above the sintering melt zone 10 where the sintering reaction is performed is a so-called sinter cake portion where the sintering reaction is completed.

As described above, in the air downward suction iron ore sintering method, air is sucked downward, and the powder coke mixed with the raw material is burned by this air, whereby a few mm in the thickness direction of the raw material on the pallet. The sintering reaction proceeds in such a manner that the sintering melt zone of several tens of mm moves downward. The lower the layer is, the more the sintering is completed, and the higher the sintering cake layer passes, and the more the sintering is performed with the preheated air, so that the combustion temperature of the coke becomes higher and the reduction potential becomes stronger. As a result of various examinations of coke combustion conditions using a mathematical model and experiments, coke combustion was 1000 to 1400 ° C. and oxygen partial pressure was 10 ⁻⁶ to 10 ^{− in} a layer having a height of 300 mm or less from the great surface. ² atm and strong reduction potential,
And because the flame front of the sinter melting zone arrives at the Great surface,
The lower temperature raw material layer disappeared, the evaporated trace metal did not solidify and deposit in the sintered layer, and the trace metal could be removed. Therefore, by allowing calcium chloride to coexist with iron scrap in a layer having a height of 300 mm or less from the grate surface, it is possible to effectively remove a trace amount of metal and produce a sintered ore having excellent chemical components even if iron scrap is used.

The calcium chloride to be mixed with the iron scrap may be a chloride, and calcium chloride was selected as the economical material which is usually easily available, but magnesium chloride and barium chloride can also be used.

Further, the mixing ratio of calcium chloride is required to be the same as the equivalent amount of copper, tin and zinc contained in the iron scrap in a weight ratio, and if it exceeds 5 times, the trace metal removal efficiency is improved. It is possible to remove trace metal components in proportion to the mixing ratio.

As a method for mixing calcium chloride and iron scrap, FIG. 1 shows a method of immersing in calcium chloride slurry, and FIG. 2 shows a method of spraying the slurry. Calcium chloride is a good water-soluble substance and can easily be made into a slurry. Further, calcium chloride in the form of slurry has a strong adhesiveness, and a slurry of adhered calcium chloride cannot be easily removed. Although neither of the above methods is accurate in the amount of calcium chloride added, the amount of calcium chloride corresponding to the trace metal component is small, and the amount ratio of calcium chloride added is 1 to 5 of copper, tin and zinc equivalents. If it is within the range, these methods are sufficient. When it is necessary to improve the accuracy of the calcium chloride addition ratio, as shown in FIG. 3, a method well known in the art, such as iron scrap and calcium chloride, is put into a raw material tank, weighed and cut out, and then the drum or the like. It is better to mix with a mixer. However, this method requires a two-stage charging device for raw materials and cannot be applied when there is only a normal one-stage charging device. However, 15m as iron scrap
A one-stage charging device using a material having a size of m or more and 150 mm or less and adding calcium chloride at a ratio of 1 to 5 times the equivalent of copper, tin and zinc contained in the iron scrap to the blended raw material The same effect can be achieved by charging with. In the sintering machine, the particles are segregated in the height direction of the sintered layer at the time of charging, and the particle size is large below the sintered layer and small above the sintered layer. In general, segregation is generally strengthened.
Therefore, in the case of iron ore sintering that normally uses an average of 2 to 3 mm of raw material, if iron scrap having a size of 15 mm or more is used, it is segregated in the lower layer of the sintered layer together with calcium chloride. If the size of the iron scrap is less than 15 mm, most of it segregates in the lower layer, but some remains in the upper layer, and it is difficult to remove a trace amount of metal sufficiently, and the removal efficiency decreases.
If it exceeds 150 mm, it will not be a sinter by the sintering machine. Therefore, the size of the iron scrap charged into the sintering machine is 15
It is preferably from mm to 150 mm.

When iron scrap chips and calcium chloride are simply mixed, a part of the calcium chloride may be separated from the iron scrap when the raw material is charged, but the iron scrap chips are sprayed with a slurry of calcium chloride or What was added to the sintering raw material after soaking in the solution,
The mixing ratio of calcium chloride cannot be strict, but it can be made equal to or more than copper, tin, and zinc equivalents, and since calcium chloride in a slurry form has strong adhesiveness, calcium chloride is removed from scrap iron during transportation until it is charged into the raw material. The rate of separation is small, and the effect of removing trace metals such as copper, tin, and zinc is stable.

In the present invention, since calcium chloride having a low melting point of 772 ° C. is used, a molten film of molten calcium chloride is formed on the surface of iron scrap during heating, a solid-liquid reaction occurs, and a liquid-solid reaction occurs. Because of the reaction, the reaction rate can be made extremely high as compared with the gas-solid reaction.

In order for the solid-liquid reaction to proceed on the surface of the iron scrap, it is desirable that copper, tin, and zinc contained in the iron scrap adhere to the surface of the scrap, but copper is a single substance independent of the iron scrap. In many cases, tin and zinc are contained in the surface-treated steel sheet in a large amount and adhere to the surface of the steel sheet, which is advantageous.

A trace amount of copper discharged as chloride in the exhaust gas,
Tin and zinc react with oxygen in the exhaust gas to form oxides, which are collected in the dust and released together with the dust to the outside of the system.
Outside the system, it is separated into non-ferrous metal and iron by dust treatment in a reducing furnace system, and copper, tin, and zinc become non-ferrous metal raw materials.

[0018]

Example 1 A DL type iron ore sinter machine having a sintering area of 600 m ² (5 m width × 120 m strand length) and a two-stage charging device, using 20 wt. And layer thickness 600mm, coke unit 4
In the sintering operation which was carried out at 0 kg / t, iron scrap chip pieces and calcium chloride were preliminarily added to the iron scrap 1 and calcium chloride 0.
The addition method of the iron scrap was changed so that 3% of the mixture mixed at a ratio of 004 was added, and the mixture was charged into the lower layer portion of the sintered layer and sintered. The iron scrap chip pieces were can chips and contained 0.014% by weight of copper, 0.169% of tin, and 0.004% of zinc by weight ratio to iron. Therefore, calcium chloride equivalent to 3 trace metal elements is iron. 0.187 for scrap 1
%Met. Since it is difficult for calcium chloride to act 100% effectively, it was set to 0.4%, which is about twice the equivalent of copper, tin and zinc in the iron scrap. The layer thickness of the upper layer of the sintered layer is 30
The thickness of the lower layer was adjusted to 0 mm and the layer thickness of the lower layer was adjusted to 300 mm. At the time of sintering, the temperature was 1250 to 1350 ° C. and the oxygen partial pressure was 10 ⁻⁴ atm when the layer thickness of the sintered melt zone was 300 mm or less from the grate surface. After confirming that the problem of trace elements had been resolved, the amount of iron scrap was increased to 10 wt% for operation. Table 1 shows the difference in the components of the trace elements in the sintered ore before and after carrying out the present invention, the basic unit of coke, NOx, and SOx.
50% of copper, 75% of tin and 85% of zinc contained in the raw materials could be removed, the removal rate of trace metals was improved, and the coke consumption rate was improved when the amount of iron scrap was increased.
NOx and SOx could be reduced.

[0019]

[Table 1]

[0020]

[Example 2] A DL type iron ore sintering machine having a sintering area of 280 m ² (4 m width x 70 m strand length) and a normal chute charging device was used, and iron scrap of a size of 20 to 80 mm was used as a total raw material of 10 wt. %, The layer thickness is 650 mm, and the coke unit is 21 kg / t.
Iron scrap chip pieces of ~ 80 mm and slurry calcium chloride were mixed in advance with a spraying machine so that the ratio of calcium chloride 0.002 to iron scrap chip piece 1 was 10% of all raw materials. The method of adding the iron scrap was changed so as to segregate the mixture into the sintering machine, and the mixture was charged and sintered. Iron scrap chip pieces are can chips, and 0.014% by weight of copper to iron,
Since it contained 0.169% tin and 0.004% zinc, the equivalent calcium chloride content of the three trace metal elements was 0.187% based on 1 scrap iron. Therefore, the amount of calcium chloride added is almost equivalent. It was confirmed by a pallet sampling test that iron scrap chip pieces were segregated in the lower layer portion of the sintering bed of 250 mm or less. At the time of sintering, the temperature when the molten zone of the sintered zone became 250 mm or less at the layer height from the grate surface was 1280 to 1370 ° C., and the oxygen partial pressure was 10
It was ^-5 atm. Table 2 shows the difference in the components of the trace elements in the sintered ore before and after the present invention was carried out. Iron scraps are all raw materials 2
Even when 0 wt% was added, the removal rate of trace metals including Cu was remarkably improved.

[0021]

[Table 2]

[0022]

EFFECTS OF THE INVENTION According to the present invention, trace components that are not good in the properties of steel such as copper, tin and zinc contained in iron scrap are volatilized without performing special treatment using an air downward suction type sintering machine. Since it can be sintered while being removed, the restrictions on the amount of iron scrap used to deteriorate the properties of steel in the past can be removed and the amount used can be increased. Reduction of basic unit, NOx,
SOx can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an apparatus for carrying out the method of the present invention.

FIG. 2 is a diagram showing another example of an apparatus for carrying out the method of the present invention.

FIG. 3 is a view showing still another example of an apparatus for carrying out the method of the present invention.

[Explanation of Codes] 1 raw material tank 1 ′ raw material tank for iron scrap 1 ″ raw material tank for calcium chloride 2 belt conveyor 3-1 mixer 3-2 spraying machine 4 mixer 5 surge hopper 6-1 lower raw material charging device 6 -2 Upper-stage raw material charging device 6'1st-stage raw material charging device 7 Ignition furnace 8 DL type sintering machine 9 Pallet 10 Sintering melt zone 11 Great surface

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masanori Tokuda 3-7-15 Minami Yagiyama, Taihaku-ku, Sendai City, Miyagi Prefecture

Claims (3)

[Claims] 1. A method for producing an air downward suction type sintered ore, wherein 1 to 1 of copper, tin and zinc equivalents contained in iron scrap is included.
Calcium chloride in a weight ratio of 5 times was mixed with iron scrap, and the mixture was charged into a range of a layer height of 300 mm or less from the great surface of the sintered layer of an air downward suction type sintering machine and sintered,
A method for producing a sintered ore, which comprises volatilizing and removing chlorine, copper, tin and zinc contained in an iron scrap, and sintering while removing the chlorine. 2. The method for producing a sintered ore according to claim 1, wherein iron scrap having a size of 15 to 150 mm is mixed with calcium chloride. 3. The production of the sintered ore according to claim 1, wherein the iron scrap chips are sprayed or dipped with a slurry of calcium chloride and then charged into a sintering machine and sintered. Method.