WO2009131242A1

WO2009131242A1 - Process for production of direct-reduced iron

Info

Publication number: WO2009131242A1
Application number: PCT/JP2009/058431
Authority: WO
Inventors: 石渡夏生; 広羽弘行; 主代晃一
Original assignee: Ｊｆｅスチール株式会社
Priority date: 2008-04-25
Filing date: 2009-04-22
Publication date: 2009-10-29
Also published as: TW201000640A; KR20100122946A; KR101234388B1; TWI424065B; US20110036204A1; CN102016080A

Abstract

A process for the production of direct-reduced iron, which comprises a step of preparing a mixed raw material, a step of charging the mixed raw material, and a reduction step. The step of preparing a mixed raw material is conducted by preparing a mixed raw material containing both an iron ore (X) which contains a high-zinc iron ore (A) containing 0.01mass% or more of zinc and 50mass% or more of iron and a carbonaceous solid reducing agent. The step of charging the mixed raw material is conducted by charging the mixed raw material onto a moving hearth. The reduction step is conducted by providing heat from above the moving hearth and reducing the mixed raw material charged onto the moving hearth to obtain a reduction product.

Description

Description Method for producing reduced iron Technical Field

The present invention relates to a method for reducing iron-containing materials using a mobile hearth furnace, and more particularly to a method for producing reduced iron from iron ore containing zinc at a high concentration. Background art

Crude steel production methods are broadly divided into the blast furnace single converter method, which produces pig iron from iron ore, and the electric furnace method, in which scrap is melted and refined. With the rise of emerging countries such as China, global crude steel production is increasing rapidly. In particular, the supply and demand for iron ore used in the blast furnace-converter method is tight, the price is rising, and high-quality iron ore is becoming difficult to obtain.

In addition to the above, a method for producing reduced iron using a mobile hearth furnace is also known. The mobile hearth furnace method is one of the processes for producing reduced metals represented by reduced iron. In the mobile hearth furnace method, iron ore and solid reductant are loaded on a horizontally moving hearth and heated by radiant heat from above to reduce the iron ore, and this reduction product on the hearth. It melts and separates slag and metal to produce reduced iron (see, for example, Japanese Patent Laid-Open Nos. 11-3 3 5 7 1 2 and 1- 1 7 2 3 1 2 .)

On the other hand, as with iron ore, the demand for zinc is increasing rapidly all over the world. There are various methods for scouring zinc, but it is common to oxidize and bake sulfide ore to make zinc oxide, and then wet or dry it to obtain zinc metal. The lack of zinc raw materials such as sulfide ore and zinc oxide is also a problem with this zinc.

In the situation where the shortage of resources such as iron raw materials and zinc raw materials has become a problem, the present inventors have focused on high zinc-containing iron ores that contain more zinc than usual in iron ores. . It is desirable to use such high zinc-containing iron ore as a raw material in the blast furnace converter method, but raw materials with a high zinc content are rarely used. The main reason is that zinc contained in the ore remains in the blast furnace as furnace wall deposits. The zinc content in the ore is brought into the blast furnace through a sintering process. Zinc brought into the blast furnace is reduced and vaporized in the furnace, but it oxidizes and aggregates at the low temperature and high oxidation potential. Inside the blast furnace shaft Walls and the like are particularly prone to agglomerate, adhering surrounding coke ore and immobilizing the packing. Such a stationary part is called “Anzat”, which makes the falling of the charged material in the furnace unstable and causes troubles such as “shelf hanging” and “slip”.

Thus, the zinc content is a component that causes troubles in blast furnace operation, but is also a valuable metal. Zinc is an indispensable metal, for example, as a raw material for batteries, as well as a material for improving the corrosion resistance of the steel sheet surface. As mentioned above, it is common to oxidize and bake sulfide ore to make zinc oxide and to make zinc metal by wet or dry method, but in recent years, iron making dust etc. A method has also been proposed in which crude zinc oxide is obtained and used as a raw material for making zinc.

For example, in the case of crude zinc oxide with a zinc concentration exceeding 1 O mass%, it is possible to obtain a high-concentration crude zinc oxide by processing such as the Wertz method, which can be used as a raw material for making zinc. . In addition, in the case of crude zinc oxide having a zinc concentration exceeding 50 m s s%, it can be used directly as crude zinc oxide used for zinc purification, such as the ISP method.

Depending on the recovered zinc concentration, the intended use of crude zinc oxide varies greatly. Naturally, the higher the zinc concentration, the more economical value, but the reduction that achieves both the production of reduced iron and high-concentration crude zinc oxide. No iron production method has been proposed.

Disclosure of the invention

An object of this invention is to provide the manufacturing method of reduced iron which enables the effective utilization of a high zinc content iron ore.

In order to achieve the above object, the present invention provides a method for producing reduced iron having the following aspects.

[1]. Mixing containing iron ore (X) containing high-zinc-containing iron ore (A) containing more than 0.0 1 in ass% zinc and 50 mass% or more of iron, and carbon-based solid reducing material A process of preparing raw materials,

A mixed raw material loading step of loading the mixed raw material on the hearth of the mobile hearth furnace, a reduction step of reducing the mixed raw material loaded on the mobile hearth by supplying heat from the upper part of the hearth, and obtaining a reduction product; The manufacturing method of reduced iron which has these.

[2]. The method for producing reduced iron according to [1], wherein the zinc-containing iron ore (A) has a force of 0.0 1 to 0.5 ni ass% and 50 to 70 tna ss% of iron. .

[3]. The method for producing reduced iron according to [1], wherein the high zinc-containing iron ore (A) and iron ore (X) have a blending ratio of 10 to 10 Oma s s%.

[4]. The method for producing reduced iron according to [1], wherein the mixed raw material loading step includes loading the agglomerated mixed raw material on a movable hearth.

[5]. The method for producing reduced iron according to [1], wherein the reduction step comprises reducing the mixed raw material at a heating temperature of 1 200 ° C or higher.

[6]. The method for producing reduced iron according to [5], wherein the heating temperature is 1 250 ° C or higher and lower than 1400 ° C. .

[7]. In the reduction step, the mixed raw material loaded on the movable hearth by supplying heat from the upper part of the hearth is reduced, and the mixed raw material is not melted or only partially melted to obtain reduced iron. [1] The method for producing reduced iron according to [1].

[8]. Furthermore, it has a recovery process for recovering crude zinc oxide from dust generated in the mobile hearth furnace,

The step of preparing the raw materials includes iron ore (X) containing high zinc-containing iron ore (A) containing zinc in an amount of 0.0 lma ss% or more and iron in an amount of 50 mass% or more, and a zinc-containing dust, The method for producing reduced iron according to [1], comprising preparing a mixed raw material containing a carbon-based solid reducing material. [9]. The method for producing reduced iron according to [8], wherein the mixed raw material has an average zinc concentration of 0.45 mass% or more.

[10]. The method for producing reduced iron according to [9], wherein the average zinc concentration is 0.45 to 0.60 mass%.

[1 1]. The zinc-containing dust is at least one dust selected from the group consisting of dust generated from a blast furnace, dust generated from a converter, and dust generated from an electric furnace [8] Method for producing reduced iron.

[1 2] In addition, a mobile hearth, which has a recovery process for recovering dust generated in the furnace and obtaining recovered dust.

The step of preparing the raw materials includes iron ore (X) containing high-zinc-containing iron ore (A) containing 0.0 lma ss% or more of zinc and 50 m ass or more of iron, and the recovered dust. The method for producing reduced iron according to [1], comprising preparing a mixed raw material containing a carbon-based solid reducing material.

[1 3].

Recovering dust generated in the mobile hearth furnace;

Loading the collected dust on the movable hearth;

The method for producing reduced iron according to [1], comprising: supplying heat from an upper part of the hearth to obtain crude zinc oxide from dust generated in the mobile hearth furnace.

[14]. The method for producing reduced iron according to [1], further comprising a melting step of melting the reduction product.

[15]. Furthermore, it has a melting step for melting the reduction product,

The mixed raw material contains iron ore (X) containing zinc-containing iron ore (A) containing zinc in an amount of at least 0.01 mass% and iron in an amount of at least 50 mass%, a carbon-based solid reducing material, The method for producing reduced iron according to [1], including a material.

[16] The method for producing reduced iron according to [14], wherein the melting step comprises melting the reduction product at a heating temperature of 1400 ° C. or higher.

[1 7]. The method for producing reduced iron according to [16], wherein the heating temperature is 1450 ° C or higher and 1500 ° C or lower.

[18]. Further, a melting step of melting the reduction product, and a recovery step of recovering crude zinc oxide from dust generated in the mobile hearth furnace, The step of preparing the raw material includes iron ore (X) containing high zinc-containing iron ore (A) containing zinc in an amount of 0.0 lma ss% or more and iron in an amount of 50 ma ss% or more, and a zinc-containing dust. The method for producing reduced iron according to [1], comprising preparing a mixed raw material comprising a carbon-based solid reducing material and a slagging material.

[19]. The method for producing reduced iron according to [18], wherein the mixed raw material has an average zinc concentration of 0.45 mass% or more.

[20]. The method for producing reduced iron according to [19], wherein the average zinc concentration is 0.45 to 0.60 mass%.

[21]. The zinc-containing dust is at least one dust selected from the group consisting of dust generated from a blast furnace, dust generated from a converter, and dust generated from an electric furnace [18] Method for producing reduced iron.

[22]. Further, a melting step of melting the reduction product, and a recovery step of recovering dust generated in the mobile hearth furnace to obtain recovered dust,

The step of preparing the raw material includes iron ore (X) containing high-zinc-containing iron ore (A) containing zinc in an amount of 0.0 lma ss% or more and iron in an amount of 50 ma ss% or more, and the recovered dust. The method for producing reduced iron according to [1], comprising preparing a mixed raw material comprising a carbon-based solid reducing material and a slagging material.

[23]. In addition,

A melting step for melting the reduction product;

Recovering dust generated in the mobile hearth furnace;

'Loading the collected dust onto the movable hearth;

[24]. Prior to the mixed raw material loading step, the carbon material loading step of loading the carbonaceous material on the mobile hearth in order to stack the mixed raw material on the mobile hearth after loading the carbonaceous material on the mobile hearth. The method for producing reduced iron according to [1]. Brief Description of Drawings

FIG. 1 is a schematic view showing an embodiment of a rotary hearth furnace used in the first embodiment.

FIG. 2 is a schematic diagram showing one embodiment of the equipment flow used in the first embodiment.

FIG. 3 is a schematic diagram (utilization of recovered dust) showing an embodiment of the equipment flow used in the first embodiment.

FIG. 4 is a schematic diagram (utilization of recovered dust) showing an embodiment of the equipment flow used in the first embodiment.

FIG. 5 is a graph showing the change in zinc concentration with respect to the blending ratio of the high zinc content ore of the mixed raw material in Example 1.

FIG. 6 is a schematic diagram showing an embodiment of a rotary hearth furnace used in the second embodiment.

FIG. 7 is a schematic diagram showing one embodiment of the facility entrance used in the second embodiment.

FIG. 8 is a schematic diagram (utilization of collected dust) showing one embodiment of the equipment flow used in the second embodiment.

FIG. 9 is a schematic diagram (using recovered dust) showing one embodiment of the equipment flow used in the second embodiment.

FIG. 10 is a graph showing the change in zinc concentration with respect to the blending ratio of the high zinc-containing ore of the mixed raw material in Example 2. Explanation of symbols

Rotary hearth furnace, 2 furnace bodies, 2a pre-tropical, 2b

2 c melting zone, 2 d cooling zone, 3 rotary hearth, 4 mixed raw material 5 nona, 6 charging device, 7 discharging device, 8 cooling device

1 1 Ore Hono Pass. 1, 2 Coal hopper, 1 3 Ironmaking hopper 1 4 Mixer, 1 5 Rotary hearth furnace, 1 6 Reduced iron outlet

1 7 Pug filter for exhaust gas duct, 1 8 Lorry for powder transfer

1 9 Suction fan, 2 0 Chimney, 2 1 Collection dust transfer conveyor 1 2 1 a First collection dust transfer conveyor 1 2 1 b Second collection dust transfer conveyor 1 2 2 First collection dust storage hopper 2 3 dust yard BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1:

The method for producing reduced iron according to Embodiment 1 includes a step of preparing a mixed raw material, a mixed raw material loading step, a reduction step, and a melting step.

The step of preparing the mixed raw material includes: an iron ore containing a high zinc-containing iron ore containing 0.0 lmass% or more of zinc and 50 mass% or more of iron; a carbon-based solid reducing material; Preparing mixed raw materials. The mixed raw material loading step comprises loading the mixed raw material on a movable hearth. The reduction step consists of reducing the mixed raw material loaded on the movable hearth by supplying heat from the top of the hearth. The melting step comprises melting the reduction product.

The present inventors considered using a mobile hearth furnace to use iron ore containing high zinc and to effectively use the contained iron and zinc contents. The method of producing granular iron using a mobile hearth furnace is one of the processes for producing reduced iron. Iron ore and solid reducing material are loaded on the hearth that moves in the horizontal direction, and radiation is applied from above. Heated by heat transfer, iron ore is reduced, the reduction product is melted on the hearth, and slag and metal are separated to produce reduced iron, which is reduced iron.

This mobile hearth furnace is a furnace that heats the hearth of the heating furnace while it moves horizontally. A horizontal moving hearth typically has the form of rotational movement as shown in Fig. 1. A mobile hearth furnace having the form of rotational movement is particularly called a rotary hearth furnace. In Embodiment 1, granular iron as reduced iron is produced by reducing and melting high-zinc-containing iron ore using such a mobile hearth furnace, particularly a rotary hearth furnace. In the following, Embodiment 1 will be described for the case where a rotary hearth furnace is used as a mobile hearth furnace.

Note that the high zinc content iron ore used in Embodiment 1 has a higher zinc content than iron ore used as a normal blast furnace raw material, and generally contains 0.0 lmass% or more of zinc and 5% of iron. Iron ore containing 0 mass% or more. The upper limit of the zinc content of the high zinc content iron ore used in Embodiment 1 is not limited, but it is naturally determined from the fact that it is an iron ore. For example, zinc is about 0.5 mass%. For iron, for example, it is about 7 O mass% or less. The content of the alkali component such as N a _₂ 0, K ₂ 0 of the high zinc-containing iron ore, in terms of oxide is usually 0. 0 8 mass% or more. The content of alkali components is preferably lmass% or less, which is one of the rotary hearth furnace exhaust gas systems. It is effective in preventing marijuana.

Embodiment 1 is a technique for producing granular iron using such high-zinc-containing iron ore. When reducing high-zinc-containing iron ore in a rotary hearth furnace, ordinary iron ore is mixed. It can also be used. Even when used in combination with ordinary iron ore, the effect of Embodiment 1 can be suitably obtained when high zinc-containing iron ore is blended in an amount of about 10 m a s s% or more of the whole ore.

An embodiment of a rotary hearth furnace used in Embodiment 1 will be described with reference to FIG. As shown in Fig. 1, the rotary hearth furnace 1 has a hearth 3 that rotates and moves in a furnace body 2 partitioned into a pre-tropical zone 2a, a reduction zone 2b, a melting zone 2c, and a cooling zone 2d. It is a cover. On this rotary hearth 3, for example, a raw material 4 made of iron ore containing high zinc and a solid reducing material is loaded. As this raw material 4, a mixed raw material in which a high zinc-containing iron ore, a carbon-based solid reducing material, and a slagging material are mixed is used. The mixed raw material can also be agglomerated as described below. The furnace body 2 covering the rotary hearth 3 is refractory. Furthermore, in order to protect the hearth refractory, there is a case where a carbon material is loaded on the hearth 3 and the raw material 4 is laminated thereon. In addition, a burner 5 is installed at the top of the furnace body 2, and the iron ore in the mixed raw material 4 on the rotary hearth 3 is reduced using the heat of fuel combustion in the burner 5 as a heat source. In FIG. 1, 6 is a charging device for charging the raw material onto the rotary hearth 3, 7 is a discharging device for discharging the reduced product, and 8 is a cooling device. In addition, the atmospheric temperature in the furnace body 2 is set to around 1300 ° C, but in the melting zone, it is usually controlled to a high temperature around 1450 ° C. '

High zinc-containing iron ore contains a gangue component, although the amount varies depending on the place of production. As typical examples of carbon-based solid reducing materials, coal, coal chain, and coatas contain ash. Therefore, the moving hearth furnace method, which performs only the reduction operation, is unavoidable that gangue is mixed in the reduced iron, which is a product, unlike the blast furnace single converter method. There is a possibility of adhering and mixing. When the raw material is reduced and melted on the hearth of the rotary hearth furnace, the metal produced by the reduction and the residual slag can be separated quickly, and high-density granular iron can be obtained. .

The granular iron obtained in the first embodiment is reduced and melted as described above to separate the slag component, and is discharged from the rotary hearth furnace before being compressed. The apparent density can be set to 5 0 00 kg Zni ³ or more. In normal cases, the product granular iron undergoes a sieving process, and the particle size becomes 3 mm or more and 10 O mm or less. When reducing high zinc-containing iron ore using a rotary hearth furnace, the iron ore with high zinc content is mixed with the carbon-based solid reducing material and ironmaking material and loaded on the rotating hearth. Carbon-based solid reducing materials include coal, coatas, graphite, and slagging materials include lime powder, dolomite, serpentine, and other basic components such as C a 0 and N a ₂ 0. .

If the high-zinc-containing iron ore is a massive ore, it can be ground and reduced to, for example, an ore powder with a particle size of 1 O mm or less, then mixed with a carbon-based solid reducing material, etc., and loaded on a rotary hearth for reduction. The

When the high-zinc-containing iron ore is finely divided ore (particle size of 3 mm or less), it can be agglomerated together with a carbon-based solid reducing material and slagging material, and used as a carbonaceous material interior pellet. The agglomerated raw material is less scattered during heating and can improve the zinc concentration of dust. Similarly, it can be compression molded and used as a pricket. In addition, during granulation, an inorganic binder such as bentonite and an organic binder such as molasses and corn starch can be mixed to increase the strength. These pellets and prickets can be used after the water has evaporated. On the other hand, it is also effective to use iron ore containing zinc oxide in powder form. By using the raw material as it is, the cost of equipment for producing the lump, electric power, binders, etc. becomes unnecessary, which can contribute to economic improvement.

The heating temperature when reducing or melting high zinc-containing iron ore in a rotary hearth furnace is preferably 140 ° C. or higher. More preferably, it is 1450 ° C or higher. By setting the maximum temperature in the rotary hearth furnace to 1450 ° C or higher, the raw material that is reduced and melted in the furnace and the furnace becomes high temperature. In particular, when the melted raw material is at 1450 ° C. or higher, sufficient fluidity can be ensured, and the gangue component in the metal iron can be easily removed, and fine iron with good properties can be obtained. It can be manufactured.

It is possible to prevent the molten metal slag from attacking the refractory of the hearth by loading the carbonaceous material on the hearth and laminating the mixed raw material containing iron ore containing high zinc on the carbonaceous material. It becomes possible. Since iron is taken into the refractory during refractory erosion, loss of iron content is reduced by preventing erosion of the refractory in the hearth, contributing to improved productivity of granular iron.

Dust contained in the exhaust gas generated in the rotary hearth furnace is recovered. Compared with high-zinc iron ore, this dust is concentrated in zinc, so it is used as raw material for crude zinc oxide. It is possible. Figure 2 shows a schematic diagram of the general equipment flow of a rotary hearth furnace that collects such dust.

In Fig. 2, the iron ore, coal, and slag material discharged from the ore hopper 1 1, coal hopper 1 2, and slagging material hopper 1 3 are mixed in a mixer 1 4 (using a pelletizer, etc. if necessary). The mixed raw material is mixed, heated in a rotary hearth furnace 15 and reduced / melted to become reduced iron, which is discharged from the reduced iron outlet 16. The exhaust gas generated in the rotary hearth furnace 15 is sucked by the suction fan 19 and discharged from the chimney 20. At that time, the dust is collected by the bag filter 17 for the exhaust gas duct. Collected dust is carried out using a lorry for powder conveyance. When high-zinc-containing iron ore is added to the mixed raw material in an amount of about 1 O m s s% or more of the entire ore, the zinc concentration in the recovered dust can be set to 1 m s s% or higher.

Dust recovered from the exhaust gas generated in the rotary hearth furnace as described above (hereinafter referred to as “first recovered dust”) is again processed by supplying heat from the top of the hearth in the rotary hearth furnace, By collecting the dust generated in the rotary hearth furnace, crude zinc oxide can be obtained. The recovered dust collected when the first collected dust is treated again in the rotary hearth furnace is referred to as “second recovered dust”. When the first recovered dust is processed in the rotary hearth furnace, only the first collected dust needs to be processed, but from the viewpoint of promoting the reduction reaction, a small amount (2 HI for the first recovered dust). Ass% or less) can also be mixed with carbon-based solid reducing material or slagging material. By making the dust again in the rotary hearth furnace in this way, the dumbbells in the first recovered dust can be concentrated as described below. If the zinc concentration in the first recovered dust is greater than or equal to a predetermined amount, the first recovered dust can be mixed with a carbon-based solid reducing material, ironmaking material, and iron ore to increase the production of granular iron. If the target zinc concentration in the second recovered dust is the same when the iron ore is mixed with the first recovered dust, the amount of iron ore added can be increased by using high zinc-containing iron ore. It is preferable because a larger amount of granular iron can be produced while concentrating zinc in the dust.

For example, as shown in Fig. 3, the concentration of zinc in the dust can be achieved by transporting the first collected dust from the dust yard 2 3 using a powder transport lorry 1 8 etc. to the rotary hearth furnace 1 5. This can be done by sucking the generated exhaust gas and collecting the dust with the bag filter 17 for the exhaust gas duct. Alternatively, as shown in Fig. 4, it can be implemented by providing a first recovered dust storage hopper 2 2 in parallel with the mixed material hopper 1 1-1 3. wear. This equipment is the same as the equipment shown in Fig. 2, except that a recovered dust transport conveyor 21 and a first collected dust storage hopper 22 are added. The recovered dust transport conveyor 1 2 1 is branched into 2 1 a and 2 1 b. The first recovered dust transport conveyor 1 2 1 a transports the first recovered dust to the first recovered dust storage hopper 2 2, It can be heated and reused in the rotary hearth furnace 15 and the second recovered dust can be extracted as a product by the second recovered dust transfer conveyor 21 b. The second recovered dust that is extracted is a fine powder, and is transported using, for example, a powder transport lorry 18.

When mixing iron ore with dust, the first recovered dust is stored in the first recovered dust storage hopper 22 and rotated by combining a small amount of carbon-based solid reducing material, ironmaking material, and iron ore. Used as raw material for hearth furnace, recovered as second recovered dust when reduced and melted in rotary hearth furnace 15.

As described above, the second recovered dust containing crude zinc oxide has different uses depending on the zinc concentration, but the second recovered dust produced by the above method has a zinc concentration exceeding 1 O mass%. Therefore, a high concentration of crude zinc oxide can be obtained by intermediate treatment such as the Wertz method, and it can be used as a raw material for zinc.

If the average zinc concentration in the ore is 0.05 mass% or more in the mixed raw material for collecting the first recovered dust, even if not all of the ore is not high-zinc-containing ore, the rotary furnace The zinc concentration of the second recovered dust obtained by processing in the floor furnace can be set to 0.5 O mass% or more. If the zinc concentration of the recovered dust obtained is 5 O m s s% or more, intermediate treatment is not necessary and it can be used directly as crude zinc oxide used for zinc scouring.

As described above, when the recovered dust (first recovered dust) is treated again in the rotary hearth furnace, the zinc concentration in the recovered dust (second recovered dust) is improved and the economy is improved. In addition, the cost of constructing a separate facility (intermediate processing facility) for dust treatment is eliminated, and the cost of transporting the generated dust to the intermediate processing facility is unnecessary.

In the above, dust contained in the exhaust gas generated in the rotary hearth furnace was recovered and used. However, zinc-containing dust other than the recovered dust was mixed when reducing high zinc-containing iron ore in the rotary hearth furnace. Can also be used. By mixing dust with higher zinc concentration than iron ore with high zinc content, the dust recovered from the exhaust gas generated in the rotary hearth furnace as described above, Dust having a high concentration of crude zinc oxide can be obtained.

As mentioned above, recovered dust containing crude zinc oxide has different uses depending on the zinc concentration, but recovered dust produced using zinc-containing dust, whether self-generated or externally generated, has a zinc concentration of l O mass Therefore, it can be made into high-concentration crude zinc oxide by an intermediate treatment such as the Wertz method, and can be used as a raw material for making zinc.

The zinc-containing dust used in combination with the high-zinc-containing iron ore is not particularly limited.For example, dust generated in the iron and steel industry, such as dust generated from a blast furnace, dust generated from a converter, dust generated from an electric furnace, etc. Can be used.

If the average zinc concentration in the mixed raw material is 0.45 m s s% or more, the zinc concentration of the recovered dust obtained by processing in the rotary hearth furnace can be set to 50 m s s% or more. If the zinc concentration of the recovered recovered soot is 50 mass% or more, intermediate treatment is not necessary, and it can be used directly as crude zinc oxide used for zinc scouring. As described above, when reducing high zinc-containing iron ore in a rotary hearth furnace, mixing zinc-containing dust increases the concentration of zinc in the recovered dust and improves economic efficiency. Hereinafter, an embodiment of the present invention will be described in detail.

A mixed raw material containing high zinc content iron ore, carbon-based solid reducing material, and ironmaking material is loaded on the hearth of the rotary hearth furnace, heated up while rotating the hearth and moving in the furnace, Air or oxygen-added air is blown into the furnace, and CO or H ₂ generated by the reduction reaction is secondarily burned. '

After the generated exhaust gas is cooled, the dust contained in the exhaust gas is recovered. On the other hand, the mixed raw material remaining on the hearth is completely melted to form a liquid, which is then cooled and solidified to obtain separated iron particles. By heating on the moving hearth,

a) Iron oxide in the ore reacts with carbon in the carbon-based solid reductant to form metallic iron. b) Iron is carburized to form gangue (S i 0 ₂ , A l ₂ 0 ³ , _Mg O, etc.) lime powder, dolomite, mixed with basic components such as C a 0, N a ₂ 0 such as serpentinite, melting point is lowered, melted,

c) By maintaining the molten state for a certain period of time, the effect of separating into molten metal iron part (metal) and molten gangue (slag) can be obtained.

It is possible to produce granular iron that can be used in the same way as pig iron. On the other hand, the zinc content in the ore exists as zinc oxide, and is reduced and volatilized by the carbon-based solid reducing material, transported to the exhaust gas, oxidizes and aggregates simultaneously with cooling, separated from the exhaust gas, and recovered as dust. This dust is concentrated in zinc, and can be used as a raw material for zinc slag by direct or re-refining process.

Since the rotary hearth furnace does not have a packed bed, phenomena such as adhesion of coatings and ores and immobilization of the packing due to the zinc content contained in the blast furnace adhering to the furnace wall occur. It will not interfere with operations. '' When the rotary hearth furnace is heated, the zinc component volatilizes and is transported to the exhaust gas. At the same time, a part of the mixed raw material loaded on the hearth is scattered and mixed with the recovered dust. Therefore, the zinc concentration in the recovered dust is determined by the amount of zinc that volatilizes and the amount of mixed raw material that scatters. The higher the zinc concentration in the mixed raw material, the higher the zinc concentration in the recovered dust. According to the study by the present inventors, it has been confirmed that the amount of the mixed raw material scattered is almost constant in normal operation, and is about 0.5 mass% of the mixed raw material input amount. In addition, the higher the zinc concentration in the dust, the higher the value as a zinc raw material. Therefore, by carrying out the present invention, dust with a high zinc concentration is recovered, and it becomes possible to use iron ore with high zinc content more effectively.

Further, by using dust recovered in all or part of the mixed raw material loaded on the rotary hearth furnace, it is also possible to further concentrate and recover zinc in the dust having a high zinc concentration. Example 1

In order to confirm the effectiveness of the present invention, in a rotary hearth furnace similar to that shown in Fig. 1, a production test of granular iron was conducted using iron ore with high zinc content and general ores with low zinc content. I went. The dust generated in the rotary hearth furnace was collected and the zinc concentration was measured. Table 1 shows the specifications of the rotary hearth furnace. In Table 2, T_Fe is the total Fe.

table 1

Table 2 shows the composition of the ore used.

Table 2

Ore A is a high zinc content iron ore, and ore B is a common ore with low zinc content. The gangue and iron content are almost the same in both cases, but the zinc concentration of ore A is about 50 times that of ore B.

Ore, coal as a carbon-based solid reducing material, and lime as a slagging material were mixed to make a mixed raw material. Table 3 shows the composition of the coal used and Table 4 shows the composition of the mixed raw materials used in the test. In Table 3, F C is fixed carbon, VM is volatile, and A sh is ash. Table 3

(massX)

Table 4

The rotary hearth furnace was operated under the conditions shown in Table 5 using Formulations 1 to 3 shown in Table 4. When coal is laid on the hearth as a carbon material with a layer thickness of 50 mm, the mixed raw material is layered with the lower layer carbon material, and the mixed raw material is not agglomerated and loaded with a layer thickness of about 10 mm. When used as "powder" The agglomerated pellets with a particle size of 10 to 15 mm are shown as “lumps” in the raw material column. Table 5

Table 6 shows the results of dust zinc concentration and iron recovery rate when granular iron was produced under the conditions shown in Table 5. Table D

In Table 6, Operation No. 3 is an example of the present invention using a high zinc content ore. The zinc concentration in the dust has risen to 7.8 ma ss%.

Operation No. 4 is an example in which about 1 Om ass% of high zinc content iron ore is blended in general ore. Even in this case, the zinc concentration in the dust has increased to 1. Oma _SS % or more. +

Operation No. 5 was heat-treated at a high temperature of 1450 ° C or higher, and it can be seen that the treatment time was shortened and the productivity was improved.

Operation No. 6 is the case where mixed raw materials are stacked on the hearth in addition to operation No. 5, and the iron recovery rate is increasing.

Operation No. 7 is the case where lump raw materials are used in addition to Operation No. 5, and the zinc concentration in the dust is increasing.

Next, the collected dust was recycled.

In the same equipment as shown in Fig. 1 and Fig. 4, the concentration of zinc in the iron ore during the production test of granular iron using general iron ore with low zinc content is high. And the relationship between the zinc concentration in the recovered dust. In the survey, ore A, which is a high-zinc-containing iron ore, and ore B, which is a normal iron ore, are mixed and used. Dust generated by the process in the rotary hearth furnace (first collected dust) is recovered, and the entire amount of recovered dust is heat-treated at 1460 ° C for 13 minutes in the hearth furnace. Dust (second recovered dust) was recovered.

Table 7 and Fig. 5 show the concentration of ore zinc in the mixed raw material and the dust generated by the first treatment in the rotary hearth furnace, which is the raw material for the second treatment in the rotary hearth furnace. 1Measurement result of zinc concentration of recovered dust and measurement result of zinc concentration of second recovered dust, which is the final product dust.

As can be seen from Table 7 and Fig. 5, when the zinc concentration of the ore in the mixed raw material becomes 0.005 ma ss% or more, the zinc concentration of the second recovered dust, which is the product dust, exceeds 5 Oma ss%, It turns out that it becomes a raw material that can be used directly for zinc refining such as ISP method. Table 7

Next, the raw material which mixed high zinc content iron ore and zinc content dust was used.

Table 8 shows the composition of the zinc-containing dust used. Here, dust generated from the converter was used as zinc-containing dust.

Table 8

In a facility similar to that shown in Fig. 1, when conducting a production test of granular iron using high-zinc-containing iron ore and zinc-containing dust, the concentration of zinc in the mixed raw material and the concentration of zinc in the recovered dust The relationship was investigated. In the survey, ore A, a high-zinc iron ore, and zinc-containing dust were mixed and used, and the zinc concentration was continuously changed to operation No. 2 1-25. In the floor furnace 1 Heat treatment was performed at 460 ° C for 13 minutes, and the generated dust was recovered.

Table 9 shows the blending ratio and zinc concentration of the zinc-containing dust in the mixed raw material, and the measurement results of the zinc concentration in the recovered dust.

Table 9

As can be seen from Table 9, the zinc concentration in the recovered dust increases with the increase in the blending ratio of the zinc-containing dust in the mixed raw material, and when the zinc concentration in the mixed raw material becomes 0.45 ma ss% or more, It can be seen that the zinc concentration of some recovered dust exceeds 5 Oma ss%, which makes it a raw material that can be used directly for zinc refining such as the ISP method.

Embodiment 2 The method for producing reduced iron according to Embodiment 2 includes a step of preparing a mixed raw material, a mixed raw material loading step, and a reduction step.

The process of preparing the mixed raw material is 0 · 0 1 m a s s for zinc. It comprises preparing a mixed raw material in which an iron ore containing a high zinc-containing iron ore containing 50 m a s s% or more of iron and a carbon-based solid reducing material is mixed. The mixed raw material loading step comprises loading the mixed raw material on a movable hearth. The reduction step consists of reducing the mixed raw material supplied from the upper part of the hearth and loaded on the movable hearth, and obtaining the reduced iron by not melting or partially melting the mixed raw material.

The present inventors have considered using a high-zinc-containing iron ore and using a mobile hearth furnace in order to effectively use the iron content and further the zinc content. The method of producing reduced iron using a mobile hearth furnace is one of the processes for producing reduced iron. Iron ore and solid reductant are loaded on the horizontal moving hearth, and radiation is transmitted from above. Reduced iron ore is heated by heat to produce reduced iron. .

This mobile hearth furnace is a furnace that heats in the process of the horizontal movement of the hearth of the heating furnace. The horizontally moving hearth has a form of rotational movement as shown in FIG. This type of mobile hearth furnace is called a rotary hearth furnace. In Embodiment 2, reduced iron is produced by reducing the high zinc-containing iron ore using such a mobile type furnace, particularly a rotary hearth furnace. In the following, Embodiment 2 will be described for the case where a rotary hearth furnace is used as the mobile S hearth furnace.

Note that the high zinc content iron ore used in Embodiment 2 has a higher zinc content than iron ore used as a normal blast furnace raw material, and generally contains 0. Iron ore containing 0 mass% or more. There is no restriction on the zinc content and the upper limit of the iron content of the zinc-containing iron ore used in Embodiment 2, but it is naturally determined because it is iron ore, and for zinc, for example, about 0.5 mass% or less, For iron, for example, it is about 7 O mass% or less. The high zinc content iron, the content of N a ₂ 0, an alkali component such as K2O stone, in terms of oxide is usually 0. 0 8 mass% or more. The content of the alkali component is preferably not more than lmass%, which is effective in preventing clogging of the rotary hearth furnace exhaust gas system. Embodiment 2 is a technique for producing reduced iron using such high zinc-containing iron ore. When reducing high zinc-containing iron ore in a rotary hearth furnace, ordinary iron ore is mixed. It can also be used. Even when used in combination with ordinary iron ore, the effect of Embodiment 2 can be suitably obtained when high zinc-containing iron ore is blended in an amount of about 1 O mass% or more of the entire ore.

An embodiment of a rotary hearth furnace used in Embodiment 2 will be described with reference to FIG. As shown in Fig. 6, the rotary hearth furnace 1 is a furnace body 2 partitioned into a pre-tropical zone 2a, a reduction zone 2b, and a cooling zone 2d. is there. On the rotary hearth 3, a mixed raw material 4 in which a high zinc-containing iron ore and a carbon-based solid reducing material are mixed is loaded. The mixed raw material 4 can also be agglomerated as described below. The furnace body 2 covering the rotary hearth 3 is refractory. In addition, in order to protect the hearth refractory, there is a case where a carbon material is loaded on the hearth 3 and the mixed raw material 4 is laminated thereon. Also, a burner 5 is installed in the furnace body 2, and the iron ore in the mixed raw material 4 on the rotary hearth 3 is reduced using the heat of fuel combustion in the burner 5 as a heat source. In FIG. 6, 6 is a charging device for charging the mixed raw material onto the rotary hearth 3, 7 is a discharging device for discharging the reduced product, and 8 is a cooling device. In general, the furnace temperature is limited to about 1300 ° C. This is because it is effective in extending the furnace refractory life. Although the present invention does not actively melt the mixed raw material, a case where a part of the mixed raw material melts during the reduction process is also included in the scope of the second embodiment.

High zinc-containing iron ore contains a gangue component, although the amount varies depending on the place of production. As typical examples of carbon-based solid reducing materials, coal, coal chain, and coatas contain ash. Therefore, the moving hearth furnace method, which performs only the reduction operation, is unavoidable that gangue is mixed in the reduced iron, which is a product, unlike the blast furnace single converter method. There is a possibility of adhering and mixing. Therefore, the reduced iron obtained in the second embodiment is not sufficiently separated from the gangue component and ash, so the apparent density (however, it was discharged from the rotary hearth furnace before being compressed) state) 5 0 0 0 kg Zm ³ less than Jo on purpose and summer.

When reducing high zinc-containing iron ore using a rotary hearth furnace, the iron ore is mixed with the carbon-based solid reducing material and loaded on the rotating hearth. Examples of the carbon-based solid reducing material include coal, coke, and graphite.

If the high-zinc iron ore is a lump ore, for example, ore powder with a particle size of 10 mm or less on the flour After that, it can be mixed with carbon-based solid reducing material and loaded on the rotary hearth for reduction.

When the high-zinc-containing iron ore is finely divided ore (particle size of 3 mm or less), it can be agglomerated with a carbon-based solid reducing material and used as a carbonaceous interior pellet. The agglomerated raw material is less scattered during heating and can improve the zinc concentration of dust. Similarly, it can be compressed before being used as a briquette. In addition, when agglomerating, an inorganic binder such as bentonite, and organic binders such as molasses and corn starch can be mixed to increase strength. These pellets can be used after the moisture has evaporated.

On the other hand, it is also effective to use high zinc-containing iron ore as it is. By using the raw material as it is, the equipment costs for producing the lump, the power for producing the lump, and the cost of the binder, etc. become unnecessary, which can contribute to the improvement of economy.

The heating temperature for reducing the high zinc-containing iron ore in the rotary hearth furnace is preferably 1250 ° C. or higher. By setting the maximum temperature in the rotary hearth furnace to 1250 ° C or higher, the raw material to be reduced in the furnace and in the furnace becomes high temperature. By setting the temperature to 1 250 ° C. or higher, the reduction reaction becomes faster and reduced iron can be produced at high speed. In the second embodiment, the upper limit of the heating temperature is a temperature at which the mixed raw material does not completely melt (less than 1450 ° C), but is controlled to be less than 1400 ° C in normal operation. The

By loading a carbonaceous material on the hearth and stacking a mixed raw material containing iron ore containing high zinc on the carbonaceous material, it is possible to prevent the partially molten mixed raw material from attacking the refractory in the hearth. Is possible. When refractory erosion occurs, iron is taken into the refractory. By preventing refractory erosion of the hearth, iron loss is reduced, which can contribute to improved productivity of reduced iron.

Dust contained in the exhaust gas generated in the rotary hearth furnace is recovered. This dust is concentrated in zinc compared to high zinc ore, so it can be used as a raw material for crude zinc oxide. Figure 7 shows a schematic diagram of the general equipment flow of a rotary hearth furnace that collects such dust.

In Fig. 7, iron ore and coal discharged from ore hopper 1 1 and coal hopper 1 2 are mixed in a mixer 1 4 (using a pelletizer, etc. if necessary) to make a mixed raw material. It is reduced by heating at 15 to be reduced iron and discharged from the reduced iron discharge port 16. Times The exhaust gas generated in the converter floor furnace 15 is sucked by the suction fan 19 and discharged from the chimney 20. At that time, dust is collected by the pug filter 17 for the exhaust gas duct. Collected dust is carried out using a lorry for powder conveyance. In the case of blending high ore containing iron ore in the mixed raw material, about 1 O mass% or more of the whole ore, the zinc concentration in the recovered dust can be set to 1 mass% or more.

Dust recovered from the exhaust gas generated in the rotary hearth furnace as described above (hereinafter referred to as “first recovered dust”) is again processed by supplying heat from the top of the hearth in the rotary hearth furnace, By collecting the dust generated in the rotary hearth furnace, crude zinc oxide can be obtained. The dust collected when the first collected dust is again processed in the rotary hearth furnace is referred to as “second recovered dust” hereinafter. When processing the first recovered dust in the rotary hearth furnace, only the first collected dust needs to be processed, but from the viewpoint of promoting the reduction reaction, a small amount of the first recovered dust (with respect to the first recovered dust). (2 mass% or less) carbon-based solid reducing material can be mixed. By making the dust again in the rotary hearth furnace in this way, the zinc in the first recovered dust can be concentrated as described below. When the zinc concentration in the first recovered dust is greater than or equal to a predetermined amount, the first recovered dust can be mixed with a carbon-based solid reducing material and iron ore to increase the amount of reduced iron produced. If the target zinc concentration in the second recovered dust is the same when the iron ore is mixed with the first recovered dust, the amount of iron ore added can be increased by using high zinc-containing iron ore. It is preferable because a larger amount of reduced iron can be produced while concentrating zinc in the dust.

For example, as shown in Fig. 8, the zinc collected in the dust is conveyed to the rotary hearth furnace 15 by transporting the first collected dust in the dust yard 23 using a lorry 18 for powder transportation. This can be done by sucking the generated exhaust gas and collecting the dust with the bag filter 17 for the exhaust gas duct. Alternatively, as shown in FIG. 9, the first recovered dust storage hopper 2 2 can be provided in parallel with the mixed material hoppers 1 1 and 1 2. This equipment is the same as the equipment shown in Fig. 7 except that a recovered dust transport conveyor 21 and a first collected dust storage hopper 22 are added. The recovered dust transport conveyor 1 2 1 is branched into 2 1 a and 2 1 b. The first recovered dust transport conveyor 1 2 1 a transports the first recovered dust to the first recovered dust storage hopper 2 2, It can be heated and reused in the rotary hearth furnace 15 and the second recovered dust can be extracted as a product by the second recovered dust transfer conveyor 21 b. The second collected dust that is extracted is a fine powder. For example, it is transported using a powder transport port 1 18 or the like.

When mixing iron ore with dust, the first recovered dust is stored in the first recovered dust storage hopper 22 and a small amount of carbon-based solid reducing material and iron ore are blended to form a rotary hearth furnace. Used as a raw material and recovered as second recovered dust when heated and reduced in a rotary hearth furnace 15.

If the average zinc concentration in the ore is 0.05 mass% or more in the mixed raw material for collecting the first recovered dust, even if not all of the ore is not high-zinc-containing ore, the rotary furnace The zinc concentration of the second recovered dust obtained by processing in the floor furnace can be 5 O mass% or more. If the zinc concentration of the recovered dust obtained is 5 O m s s% or more, intermediate treatment is not necessary and it can be used directly as crude zinc oxide used for zinc scouring.

In the above, dust contained in the exhaust gas generated in the rotary hearth furnace was recovered and used. However, zinc-containing dust other than the recovered dust was mixed when reducing high zinc-containing iron ore in the rotary hearth furnace. Can also be used. By mixing dust with higher zinc concentration than iron ore with high zinc content, it is possible to obtain dust having a high concentration of crude zinc oxide in the dust recovered from the exhaust gas generated in the rotary hearth furnace as described above. it can.

As mentioned above, recovered dust containing crude zinc oxide has different uses depending on the zinc concentration, but the recovered dust produced using zinc-containing dust, whether self-generated or externally generated, has a zinc concentration of 1 O mass. Therefore, it can be made into high-concentration crude zinc oxide by an intermediate treatment such as the Wertz method, and can be used as a raw material for making zinc.

The zinc-containing dust used in combination with the high zinc-containing iron ore is not particularly limited. For example, dust generated in the iron and steel industry, such as dust generated from a blast furnace, dust generated from a converter, and dust generated from an electric furnace can be used.

If the average zinc concentration in the mixed raw material is 0.45 m a s s% or more, the sub-10 concentration of recovered dust obtained by processing in the rotary hearth furnace can be made 5 O m a s s% or more. If the recovered recovered zinc concentration is 50 m s s% or more, intermediate treatment is unnecessary, and it can be used directly as crude zinc oxide used for zinc scouring.

As described above, when reducing high zinc-containing iron ore in a rotary hearth furnace, mixing zinc-containing dust increases the concentration of zinc in the recovered dust and improves economic efficiency. One embodiment of the second embodiment will be described in detail below.

A mixed raw material containing high zinc-containing iron ore and carbon-based solid reducing agent is loaded on the hearth of the rotary hearth furnace, heated up while moving inside the furnace by rotating the hearth, and added with air or oxygen The blown air is blown into the furnace, and CO or H ₂ generated by the reduction reaction is secondarily burned. appear

After the exhaust gas is cooled, the dust contained in the exhaust gas is recovered. The mixed raw material remaining on the hearth is sufficiently reduced to obtain reduced iron.

On the other hand, the zinc content in the ore exists as zinc oxide, and is reduced and volatilized by the carbon-based solid reducing material, transported to the exhaust gas, oxidizes and aggregates simultaneously with cooling, separated from the exhaust gas, and recovered as dust. This dust is concentrated in zinc, and can be used as a raw material for zinc slag by direct or re-refining process.

Since the rotary hearth furnace does not have a packed bed, phenomena such as adhesion of coatus and ore, immobilization of the packing due to adhesion of the zinc content contained in the raw material to the furnace wall, as seen in a blast furnace, occur. Will not interfere with operations.

When the rotary hearth furnace is heated, the zinc component volatilizes and is transported to the exhaust gas. At the same time, a part of the mixed raw material loaded on the hearth is scattered and mixed with the recovered dust. Therefore, the zinc concentration in the recovered dust is determined by the amount of zinc that volatilizes and the amount of mixed raw material that scatters. The higher the zinc concentration in the mixed raw material, the higher the zinc concentration in the recovered dust. According to the study by the present inventors, it has been confirmed that the amount of the mixed raw material scattered is almost constant in normal operation, and is about 0.5 mass% of the mixed raw material input amount. In addition, the higher the zinc concentration in the dust, the higher the value as a zinc raw material. Therefore, the second embodiment is implemented. By applying this, dust with a high zinc concentration is recovered, and iron ores with high zinc content can be used more effectively.

Further, by using dust recovered in all or part of the mixed raw material loaded on the rotary hearth furnace, it is also possible to further concentrate and recover zinc in the dust having a high zinc concentration.

Example 2

In order to confirm the effectiveness of the second embodiment, in a rotary hearth furnace similar to that shown in Fig. 6, a production test of reduced iron using high-zinc-containing iron ore and general ore with low zinc content is performed. Test was carried out. Moreover, the dust generated in the rotary hearth furnace was recovered and the zinc concentration was also measured. Table 10 shows the specifications of the rotary hearth furnace.

Table 1 0

Table 11 shows the composition of the ore used. In Table 11, T 1 F e is the total F e.

Table 1 1

Ore A is a high zinc content iron ore, and ore B is a common ore with low zinc content. The gangue and iron contents are almost the same, but the zinc concentration of ore A is about 50 times that of ore B.

Ore and coal as a carbon-based solid reducing material were mixed to make a mixed raw material. Table 12 shows the composition of the coal used, and Table 13 shows the composition of the mixed raw materials used in the test. In Table 12, FC is fixed carbon, VM is volatile, and Ash is ash.

(k / tHron)

The rotary hearth furnace was operated under the conditions shown in Table 14 using the formulations 1 to 3 shown in Table 13. When 5 O mm of coal is laid on the hearth as a carbon material, the mixed raw material is laminated with the lower layer carbon material, and when the mixed raw material is loaded with about 1 O mm and used, it is “powder”. The agglomerated pellets with a particle size of 10 to 15 mm are shown as “lumps” in the raw material column. Table 1 4

Table 15 shows the results of dust zinc concentration and iron recovery rate when reduced iron was produced under the conditions shown in Table 14. Table 15

In Table 15, Operation No. 3 is an example of the present invention using a high zinc content ore. The zinc concentration in the dust has increased to 7.6 ma ss%.

Operation No. 4 is an example of a case where about 10 m a s s% of high zinc content iron ore is blended in general ore. Even in this case, the zinc concentration in the dust has risen to more than 1.0 ma s s%.

Operation No. 5 was heat-treated at a high temperature of 1 250 ° C or higher, and it can be seen that the treatment time was shortened and the productivity was improved.

Operation No. 7 is the case where lump raw materials are used in addition to Operation No. 5, and the zinc concentration in the dust is increasing. Next, the collected dust was recycled.

In the same equipment as shown in Fig. 6 and Fig. 9, when conducting the production test of reduced iron using general ore with low zinc content in high-zinc-containing iron ore, The relationship between the collected dust and zinc concentration was investigated. In the survey, ore A, which is a high-zinc content ore, and ore B, which is a normal ore, are mixed and used, and the zinc concentration is continuously changed to operation No. 1 1 to 19 and the first rotation. Dust generated by treatment in hearth furnace (first recovery das G) was collected, and the entire amount of collected dust was heated in a rotary hearth furnace at 1260 ° C for 13 minutes, and the generated dust (second collected dust) was collected.

Table 16 and Fig. 10 show the ore zinc concentration in the mixed raw material and the dust generated by the treatment in the first rotary hearth furnace. The measurement result of the zinc concentration of the first recovered dust and the measurement result of the zinc concentration of the second recovered dust, which is the final product dust. Table 1 6

As can be seen from Table 16 and Fig. 10, when the zinc concentration of the ore in the mixed raw material is 0.005 ma ss% or more, the zinc concentration of the second recovered dust, which is product dust, exceeds 5 Oma ss%, It turns out that it becomes a raw material that can be used directly for zinc refining such as ISP method. Next, the raw material which mixed high zinc content iron ore and zinc content dust was used.

The composition of the zinc-containing dust used is shown in Table 17. Here, dust generated from the converter was used as zinc-containing dust.

Table 1 7

When a production test of reduced iron is performed using high zinc content iron ore and zinc content dust with the same equipment as shown in Fig. 6, the zinc concentration in the mixed raw material and the zinc concentration in the recovered dust The relationship was investigated. In the survey, ore A, which is a high-zinc iron ore, and zinc-containing dust are mixed and used, and the zinc concentration is continuously changed to operate No. 2 1-25. Heat treatment was performed in a furnace at 1260 ° C for 13 minutes, and the generated dust was recovered.

Table 18 shows the measurement results of the mixing ratio and zinc concentration of zinc-containing dust in the mixed raw material, and the zinc concentration of recovered dust.

Table 1 8

As can be seen from Table 18, when the zinc concentration in the recovered dust increases as the blending ratio of the zinc-containing dust in the mixed raw material increases, and the zinc concentration in the mixed raw material reaches 0.45 mass% or more, It can be seen that the zinc concentration of the recovered dust, which is product dust, exceeds 5 O mass%, making it a raw material that can be used directly in zinc refineries such as the ISP method.

Claims

The scope of the claims

1 · Prepare a mixed raw material containing iron ore (X) containing high-zinc-containing iron ore (A) containing 0.01 mass% or more of zinc and 50 mass% or more of iron, and a carbon-based solid reducing material Process,

A mixed raw material loading step of loading the mixed raw material on the hearth of the mobile hearth furnace, a reduction step of reducing the mixed raw material loaded on the mobile hearth by supplying heat from the upper part of the hearth, and obtaining a reduction product; ,

The manufacturing method of reduced iron which has this.

2. The method for producing reduced iron according to claim 1, wherein the high-zinc-containing iron ore (A) has a force of 0.01 to 0.5 m s s% zinc and 50 to 70 m s s% iron.

3. The method for producing return iron according to claim 1, wherein the high zinc-containing iron ore (A) 1 iron ore (X) has a blending ratio of 10 to 100 m a s s%.

4. The method for producing reduced iron according to claim 1, wherein the mixed raw material loading step comprises loading the agglomerated mixed raw material on a movable hearth.

5. The method for producing reduced iron according to claim 1, wherein the reduction step comprises reducing the mixed raw material at a heating temperature of 1 200 ° C or higher.

6. The method for producing reduced iron according to claim 5, wherein the heating temperature is 1 250 ° C or higher and lower than 1 400 ° C.

7. The reduction step consists of reducing the mixed raw material loaded on the movable hearth by supplying heat from the upper part of the hearth, and obtaining the reduced iron by not melting or partially melting the mixed raw material The method for producing reduced iron according to claim 1.

8. Furthermore, it has a recovery step of recovering crude zinc oxide from dust generated in the mobile hearth furnace,

The step of preparing the raw material includes iron ore (X) containing high zinc-containing iron ore (A) containing zinc in an amount of 0. Olma ss% or more and iron in an amount of 50 ma ss% or more, and a zinc-containing dust. Preparing a mixed raw material containing a carbon-based solid reducing material,

The method for producing reduced iron according to claim 1.

9. The method for producing reduced iron according to claim 8, wherein the mixed raw material has an average zinc concentration of 0.45 mass% or more.

10. The method for producing reduced iron according to claim 9, wherein the average zinc concentration is 0.45 to 0.6.6 Oma s s%.

1 1. The zinc-containing dust is at least one dust selected from the group consisting of dust generated from a blast furnace, dust generated from a converter, and dust generated from an electric furnace. Production method.

1 2.Furthermore, it has a recovery process to recover the dust generated in the mobile hearth furnace and obtain the recovered dust.

The step of preparing the raw material includes: iron ore (X) containing high-zinc-containing iron ore (A) containing not less than 0.0 Ima ss% zinc and not less than 50 mass% of iron; and the recovered dust, Comprising preparing a mixed raw material containing a carbon-based solid reducing material,

The method for producing reduced iron according to claim 1.

13. In addition,

Recovering dust generated in the mobile hearth furnace;

Loading the collected dust on the movable hearth;

Supplying crude heat from the upper part of the hearth to obtain crude zinc oxide from dust generated in the mobile hearth furnace;

The method for producing reduced iron according to claim 1, comprising:

14. The method for producing reduced iron according to claim 1, further comprising a melting step of melting the reduction product.

1 5. Furthermore, it has a melting step of melting the reduction product,

The mixed raw material includes iron ore (X) containing high-zinc-containing iron ore (A) containing zinc in an amount of 0.01 mass% or more and iron in an amount of 50 mass% or more, a carbon-based solid reducing material, Including materials,

The method for producing reduced iron according to claim 1.

1 6. The method for producing reduced iron according to claim 14, wherein the melting step comprises melting the reduction product at a heating temperature of 1400 ° C or higher.

1 7. The method for producing reduced iron according to claim 16, wherein the heating temperature is 1450 ° C or higher and 1500 ° C or lower.

1 8. Furthermore, it has a melting step of melting the reduction product, and a recovery step of recovering crude zinc oxide from dust generated in the mobile hearth furnace,

The step of preparing the raw material includes iron ore (X) containing high zinc-containing iron ore (A) containing zinc in an amount of 0.0 lma ss% or more and iron in an amount of 50 ma ss% or more, and a zinc-containing dust. The method for producing reduced iron according to claim 1, comprising preparing a mixed raw material containing a carbon-based solid reducing material and a slagging material.

19. The method for producing reduced iron according to claim 18, wherein the mixed raw material has an average zinc concentration of 0.45 mass% or more.

20. The method for producing reduced iron according to claim 19, wherein the average zinc concentration is 0.45 to 0.6 mass%.

21. The reduced iron according to claim 18, wherein the zinc-containing dust is at least one dust selected from the group consisting of dust generated from a blast furnace, dust generated from a converter, and dust generated from an electric furnace. Manufacturing method.

2 2. Further, a melting step of melting the reduction product, and a recovery step of recovering dust generated in the mobile hearth furnace to obtain recovered dust,

The step of preparing the raw material includes iron ore (X) containing a high zinc-containing iron ore (A) containing zinc at 0.0 lmass% or more and iron at 5 O mass% or more, and the recovered dust, 2. The method for producing reduced iron according to claim 1, comprising preparing a mixed raw material containing a carbon-based solid reducing material and a slagging material.

2 3.

A melting step for melting the reduction product;

Recovering dust generated in the mobile hearth furnace;

Loading the collected dust on the movable hearth;

The method for producing reduced iron according to claim 1, comprising:

2 4. Prior to the mixed raw material loading step, a carbon material loading step for loading the carbonaceous material on the mobile hearth in order to stack the mixed raw material on the mobile hearth after loading the carbonaceous material on the mobile hearth. The method for producing reduced iron according to claim 1.