JPS6260826A - Pretreatment of sintering material - Google Patents

Abstract

PURPOSE:To improve the permeability of a sintering material layer inexpensively by incorporating, to a starting material for sintering, ore fines with specific grain size having superior pseudo-pelletizing property together with an ore having inferior pseudo-pelletizing property each by a proper quantity and by pelletizing the resulting mixture. CONSTITUTION:To the starting material for sintering, ore fines of Mt. Newman, etc., having an average grain diameter ratio to the above material of <=0.04 and having superior pseudo-pelletizing property are incorporated in an amount ranging between the content of an ore of Yampi Sound, etc., with <=0.5mm grain size having inferior pseudo-pelletizing property and 75wt%, which is subjected to pelletizing by use of a pelletizer such as drum mixer. In this way, pseudo-pelletization of sintering material is accelerated and the permeability of sintering material layer is improved. As a result, the blending amount of expensive binder such as quick lime can be reduced and simultaneously that of inexpensive ore fines having inferior pseudo-pelletizing property can be increased.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention is directed to the production of sintered ore, which is the main charge of a blast furnace, in a Dwight Lloyd sintering machine. It relates to the process of granulating raw materials with a granulator such as a drum mixer.

[Background of the invention] Sintered ore is produced by charging fine ore, limestone powder, return ore, coke powder, quicklime, etc. into a drum mixer, mixing, watering, and granulating, and then placing it on the pallet of the sintering machine. It is charged and fired to a predetermined layer thickness.

Firing is carried out sequentially from the top of the raw material layer to the bottom by sucking air from the upper layer of the raw material with a fan from below the pallet. The upper layer of the raw material is ignited immediately after the raw material is loaded onto the pallet.

The productivity of sintered ore strongly depends on the permeability of the raw material layer charged on the pallet before ignition, so sintering is done by adding 1 to 2% of an expensive binder such as quicklime and granulating it. The reality is that the formation of pseudo-particles in the raw material is promoted, and as a result, the permeability of the raw material layer is ensured.

In addition, the particle size of the ores used as sintering raw materials tends to become smaller, and moreover, there is a tendency to incorporate a large amount of cheap ores that are difficult to make into pseudo-particles.Both of these factors worsen the permeability of the raw material layer. Therefore, in some cases, the product is granulated using a pan pelletizer and then granulated again using a drum mixer.

Pseudo-particle formation of the sintering raw material can be expressed by the extent to which pseudo-particles are formed as shown in FIG. 3 by granulation using a granulator such as a drum mixer. In FIG. 3, 1 is a core ore, 2 is a fine ore, 3 is coke powder, and 4 is a slag forming agent.

FIG. 4 shows the particle size distribution of true particles before granulation and the particle size distribution of pseudo particles after granulation, and shows changes in particle size distribution due to granulation. As shown in Figure 4, the particle size is 0.5 mm.
Pseudo-particles are formed when the following fine powder particles adhere to core particles with a particle diameter of 1.0 mm or more. Pseudo-particle forming property indicates the degree of this adhesion, and the better the pseudo-particle forming property is, the larger the pseudo particle diameter becomes, and the air permeability of the raw material layer is improved. Therefore, the pseudo-particulate property can be evaluated by the air permeability of the raw material layer. Note that air permeability can be expressed by JPU expressed by equation (1).

JPU=v(h/Δp)”6 (1) However, V is the superficial flow velocity, h is the raw material layer thickness (mm), and Δp is the pressure loss of the raw material layer (mmH20).

[Object of the invention] The present invention aims to reduce the amount of expensive binders such as quicklime that are added for the purpose of promoting pseudo-granulation properties of sintering raw materials, and The purpose is to promote the formation of pseudo-particles in the sintering raw material and improve the air permeability of the raw material layer so that the blended amount of fine ore can be increased.

[Summary of the Invention] In order to achieve the above object, the method for pre-processing a sintering raw material of the present invention involves adding ore to the sintering raw material, which has an average particle size ratio of 0604 or less with respect to the raw material and has good quasi-grainability. It is granulated by containing fine powder in a range of 75% (wt%, hereinafter the same shall apply) or more than the content of ore which has a particle size of 0.5 mm or less and has poor pseudo-granulation property.

[Embodiments of the invention] Three types of ores A, B1. with different pseudo-grainability.
C.

is granulated with limestone powder with a particle size of 3 mm or less and coke powder with a particle size of 3 mm or less in a small drum mixer with a diameter of 300 mm and a length of 280 mm.
Air permeability was measured on small sintered steel pieces of mm. Ore AI is Mount Newman (Mt, Newsan), f
f, stone B1 is Robe River
, Ore C1 is a yampi sound (Ya intestinal pi 5oun
d).

The particle size distribution of each is the same and is shown in Table 1. In addition, Table 1 shows ore A2. which will be described later. B2゜C2
, C3 and the particle size distribution of limestone are also shown.

The measurement results of the air permeability are shown in FIG. 5. In FIG. 5, ore A1. B1. The respective JPUs of C1 are shown in relation to moisture. As is clear from FIG. 5, the air permeability is A, B1. It decreases in the order of G1. Therefore, the pseudo-particulate property is also A1. B1. It deteriorates in the order of C1.

By the way, the air permeability of the raw material layer can be dramatically improved by adding and granulating fine ore with good pseudo-granulation properties to an average particle size ratio of 0.04 or less with respect to the sintered raw material. . Regarding this matter, please refer to the patent application already filed (1986).
Application filed on July 25, 2015, “Method for evaluating pseudo-particle formation of sintering raw materials”;
(Application filed on July 26, 1985 “Pre-treatment method for sintering raw materials”)
It is also shown in the specification.

FIG. 6 is a graph showing the relationship between the average particle diameter ratio (approximate value) of the fine ore added to the sintering raw material and the air permeability of the raw material layer. The sintering raw material includes ore C1 with a particle size of 5 mm or less.
Limestone with a particle size of 3 mm or less, coke powder with a particle size of 3 mm or less, added fine powder part side A (ore A1, same type of ore as A2), average particle size of 32 pm, 84 JLm
, 9 Bpm, and 384 uLm were used for 35%. Granulation was performed using a drum mixer with a diameter of 300 mm and a length of 280 mm, and air permeability was measured using a drum mixer with a diameter of 105 mm.
The experiment was carried out using sintered steel with a height of 400 mm. Here, the relative air permeability and average particle diameter ratio shown in FIG. 6 can be expressed by the following equations (2) and (3), respectively.

JPU when fine ore is not added Average particle size of fine ore (tm) As is clear from Figure 6, the permeability of the raw material layer is as follows when the above average particle size ratio of fine ore added is 0.04 or less Especially improved.

Using the same experimental method, we investigated the optimal amount of fine ore to be added. The raw materials include ore A1. shown in Table 1. A.

B, , B2. C,, C2, C3, limestone, coke powder with a particle size of 3 mm or less and an average particle size of 32 pm
Fine ore A was used. In addition, in Table 1, A1, A B, BCC, and C3 are the same 2°, respectively.
1 2'l' Consisting of two types of iron ore A, B and C, each subscript is the particle size! It means 5 different things. Table 2 shows the mixing ratio (%) of the raw materials without the addition of the fine ore. Table 2 shows raw materials corresponding to the symbols used in FIG. 1 below. When fine ore was added, the blending ratio of limestone and coke powder was the same, and the blending ratio of ores A, B, and C was kept constant. Obtained in this way. Figure 1 shows the relationship between the amount of Wk fine ore added and the JPU of the raw material.

As can be seen from FIG. 1, the air permeability of each raw material gradually improves with the addition of fine ore, and increases rapidly from a certain value. If more than 50% is added, the particles become pseudo-particles mainly composed of fine ore and are destroyed when charged into sintered steel, resulting in poor air permeability; however, up to about 75%, if no fine ore is added. It shows superior breathability.

The point at which the air permeability begins to improve rapidly is indicated by the broken line in Figure 1, and the point at which the particle size in the total raw material at that point is 0.5 mm.
The permeability of each raw material layer using the same ore A, ore B, and ore C with a zero particle size distribution is shown in Figure 1 as a numerical value in the following ratio (%) of ore C.

As shown in FIG. 5, B and C decrease in this order. Therefore, the minimum necessary amount of fine ore A to improve air permeability is equal to the proportion of raw ore with poor pseudo-granulation properties that have a particle size of 0.5 mm or less, and the relationship between the two is As shown in the figure.

The reason why the air permeability improves as shown in Figure 1 is that the fine powder of ore A, which has good pseudo-granulation properties, is mixed with the ore with a particle diameter of 0.5 mm or less, which is a raw material with poor pseudo-granulation properties, and each particle has a diameter of 1 mm or more. This is because pseudo particles are formed that adhere to the core material. That is, the fine ore A exhibits the same effect as binders such as quicklime and slaked lime.

Ores with good pseudo-grainability include, for example, soft hematite ores such as Mount Newman, Hammersley, and Goldwage from Australia, Rope River from Australia, and Donimalai (soft hematite ore) from India. Examples of ores with poor pseudo-grainability include hard hematite ores such as Yumpy Sound from Australia, Rio Doce and MBR from Brazil, Carol Lake, Tass (magnetite ore) and iron sand from Canada.

As described above, ore fine powder with good pseudo-granulation properties having an average particle size ratio of 0°04 or less with the sintering raw material can be used as a pseudo-granulation powder with a particle diameter of 0.5 mm or less in the sintering raw material. It can be seen that the air permeability of the raw material layer is dramatically improved by including it in the sintering raw material and granulating it in a range of up to 75% of the content of ores with poor quality.

[Effect of the invention] The present invention provides the following effects.

(2) Expensive binders such as quicklime, which are usually added in an amount of 1 to 2% to ensure breathability of the raw material layer, can be eliminated. That is, when 1 to 2% of quicklime is added, the air permeability becomes 1.1 to 1.3 times that of no addition, and the method of the present invention surpasses the effect of adding quicklime by 1n.

(2) A large amount of inexpensive fine powder ore 1 with poor pseudo-granularity, such as Yampi Sound, can be blended.

[Brief explanation of the drawing]

Figure 1 is a graph showing the effect of the amount of fine ore A added on the air permeability of the raw material layer, Figure 2 is a graph showing the required minimum amount of fine ore A to be added, and Figure 3 is a schematic diagram showing the structure of pseudo particles. Figure 4 is a graph showing changes in particle size distribution due to granulation,
FIG. 5 is a graph showing the effect of ore brand and moisture on the air permeability of the raw material layer, and FIG. 6 is a graph showing the effect of the average particle diameter ratio of the added fine ore on the air permeability of the raw material layer. 1... Core ore, 2... Fine ore, 3... Coke powder, 4... Slag forming material. 1/rR Figure 2 Figure 3 Figure 4rI! J 'PL 3 (k (mm) Fig. 5 Wood/71' (%) Fig. 6 4 Roken J Kaihi (-)

Claims (1)

[Claims] Fine ore powder having an average particle size ratio of 0.04 or less with the raw material and having good quasi-grainability is added to the sintering raw material, and the particle size is 0.04.
A method for pre-processing a sintering raw material, characterized by granulating it by granulating it in a range of 5 mm or less and a content of ore having poor pseudo-granulation properties and 75 wt% or less.