KR950013825B1 - Making method of non-baking pellet - Google Patents

Abstract

The method comprises adding the compound of sintering dust and EC dust as a substitute for a cement binder, and maintaining the adding percentage of dust compound 15 wt.% per 1 wt.% cement binder and below 60 weight% per total mixture

Description

Manufacturing method of non-fired pellet

The present invention relates to a method for producing non-fired pellets for steel making using cement as a binder and mainly powdered iron ore, and in particular, cement-based non-fired, which can substitute iron ore or iron-containing steel dust as a raw material such as binder powder. It relates to a method for producing a pellet.

In general, it is known that the non-baked mass (pellet) manufacturing method using powdered iron ore and cement as a raw material has a great effect in terms of reduction in manufacturing cost and reduction of pollution compared to other bulk manufacturing methods due to the characteristics of the manufacturing process.

That is, in the conventional sintered or sintered pellet manufacturing process, since the high-strength mass is usually made through high temperature firing at 1200-1450 ° C, expensive fuel is required, and in addition, exhaust gas containing fine dust and harmful components is produced during the manufacturing process. There is a problem that is generated in large quantities.

On the other hand, non-plastic agglomeration has the effect of reducing the manufacturing cost and reducing the pollution since the solid mass is produced by the hydration reaction of cements added as a binder at a low temperature up to about 300 ° C. or less.

The quality required as the non-fired bulking material for steelmaking is ringability and strength. In the case of conventional cement-based non-fired pellets, since the amount of open pores is higher than that of the fired pellets, the reduction property is excellent, but the non-fired steel used for steelmaking The strength of the pellets is about 150kg / piece for blast furnaces and about 30kg / pieces for converters.In order to reach this level of strength by the usual method, about 10% by weight of binder cement is used for blast furnaces, and for converters. Up to about 5% by weight.

However, in the case of Portland cement or cement clinker used as a binder is expensive, in order to reduce the cost of the binder, the present inventors modify the slag generated in the blast furnace or converter during the steelmaking process, and also replace the cements. A method of assembling cements in two stages has been proposed (Korean Patent No. 39500, Method for Assembling Non-fired Pellets). there was.

The present inventors have found that non-fired pellets in a cement flow iteoseo CaO-SiO _2, in a mainly cement strength of the binder _{CaO, CaO-SiO 2 -Al 2} O 3 , etc. by the reaction of the compound with water CaO-SiO ₂ -H A series of investigations on the iron-containing raw materials of various compositions in view of the fact that it proceeds by a hydration reaction to produce hydrates such as ₂ O, Ca (OH) ₂ , CaO-SiO ₂ -Al ₂ O ₃ -H ₂ O and As a result of the experiment, certain hydrides contained in dry dust of iron-containing dust and converter flue gas of specific heavy sintering process in dry iron dust and iron dust of converter flue gas during sintering process It was confirmed that it can cause a reaction.

Therefore, in order to reduce the amount of cement binder, the present invention substitutes the cement binder by using iron-containing dust containing a specific compound having a hydration reaction similar to that of cement, thereby maintaining the binder addition amount while maintaining the level above the strength of the existing iron ore blending material. It is an object of the present invention to provide a method for manufacturing non-fired pellets that can be reduced.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

The present invention, in the method for producing non-plastic pellets by adding 2-10% by weight of cement-based binder to the iron-containing raw material, the cement-based binder is partially added to the sintered dust and the EC seed dust mixture, and the dust mixture Alternative addition ratio is added to 15% by weight or more per 1% by weight of the cement-based binder, and the amount of the dust mixture is added to a method for producing non-fired pellets, characterized in that 60% by weight or less based on the total blended raw materials.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

In the present invention, the total amount of cement added may be variously selected from the type of furnace to be charged, but in general, 8-10% by weight of the total raw materials for the blast furnace in the operation of the steel mill, 2-6% by weight for the converter Since it is added, it can be applied to the non-baking pellet manufacturing process which usually adds 2-10% by weight of cement.

In addition, in the present invention, the type of dust (dust) capable of exerting sufficient pellet strength by working with the cement binder is the dust (hereinafter referred to as converter EC dust) generated by the exhaust gas of the converter process in the evaporative cooler and the sintering process. As the generated dust (hereinafter referred to as sintered dust), the converter EC dust and sintered dust are assumed to be composed of dust containing both CaO-SiO ₂ and CaO compounds, which are compounds that can actually cause hydration reactions. do.

This is indicated by iron ore and portland cement, cement klinger and

TABLE 1

As shown in Table 1, there is almost no CaO component in iron ore, but among the various steel dusts, the CaO component is minimized by 5 wt% or more except for columnar dust and DC (dust catcher) dust generated in the blast furnace process. I can see that there is. However, as a result of X-ray diffraction analysis to examine the constituents of the various iron powders, as shown in Table 2 below, which shows the constituents of the various dust particles, the iron powder contains a lot of CaO components, but it is actually a hydration reaction. Particularly, dust containing CaO-SiO ₂ and CaO compounds, which can cause ions, is collected in the form of electrostatic sedimentation among dry ground dusts of sinter dust and converter flue gas (hereinafter referred to as converter EC dust) and converter EC. It can be seen that it is dust.

TABLE 2

In the present invention, it is possible to maintain the properties above the strength level of the existing non-fired pellets by mixing and adding the converter EC dust and the sintered dust in place of the cement binder. In this case, the dust mixture to be added is preferably added at 15% by weight or more per 1% by weight of the cement binder, because if the dust mixture is added to 15% by weight or less per 1% by weight of the cement binder, non-plastic This is because the strength of the pellet is deteriorated compared to the existing pellet strength, which is not preferable.

However, the addition of the dust mixture to 60% by weight or more relative to the total blended material mainly composed of iron ore is not preferable for the purpose because the strength is lowered compared to the conventional pellet strength.

In addition, when the sintered dust and converter EC dust is added, it is more preferable to mix and add the sintered dust converter EC dust in a ratio of 1: 1, which is to adjust the iron content, which is similar to the iron content of iron ore, to 60% by weight. In addition, in terms of strength, the strength of the dust pellet without the binder was about 50% of the compressive strength of the iron ore blended material with the binder.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

Each of Table 2 on the basis of the compressive strength of the pellets prepared by assembling 5% by weight of cement clinker as a binder to the iron ore blending material equally blended five kinds of iron ore according to the table 1 as a binder. The strength of the pellets when 5% by weight of cement clinker was mixed with each steel dust and without mixing was measured, and the results are shown in Table 3 below. At this time, as granulation and curing conditions, after mixing each powder raw material in a mixer, assembled pellets of 10-12mm in diameter so that water is about 8-15% by weight in a fan-type pelletizer, and then the sealed container of about 60 ℃ After the heat treatment for 3 days, the mixture was dried for 2 hours in a hot air dryer at 120 ° C., and 50 pellet particles were taken to measure the compressive strength.

TABLE 3

As shown in Table 3, the sintered dust [Example (2B)] and converter EC dust [Example (7B)] had a compressive strength of 45 kg / piece and 44.3 kg / piece when the binder was added. As a result, the compressive strength was better than 33.1 kg / piece in the case of the iron ore compounding material [Example (1B)] to which the same amount of binder was added, and in the case of these dusts, Example (2A) and Example (7A) Even if no binder is added, the compressive strength reaches 17.9 kg / piece and 16.7kg / piece, thereby compressing at least about 50% of the compressive strength in the case of Example 1B, which is the iron ore compounding material to which the binder is added. In addition to showing the strength, it was found that the compressive strength of Example 1A, which is the iron ore compounding material under the same conditions, was superior to 4.2 kg / piece.

On the other hand, in the case of dust other than the binder, addition of the binder is equivalent to the compressive strength of the iron ore compound material [Example (1B)], or some shows excellent compressive strength, but when no binder is added, the iron ore compounding material [Example ( Although the compressive strength of 1A)] is slightly higher than that of the iron ore blended raw material [Example (1B)], the compressive strength is about 7.3-25%, indicating that the binder replacement effect cannot be expected.

Therefore, it can be seen that in the case of the sintered dust and converter EC dust, it is possible to replace some of the bonding effect of the cement clinker as a binder.

Example 2

In order to confirm the amount of binder reduction according to the mixing ratio of the sintered dust and converter EC dust, which express high compressive strength even when no binder is added from Example 1, the iron ore compounding material mixed in equal amounts of the five iron ores shown in Table 1 above, After mixing the mixture of sintered dust and converter EC dust (mixing ratio = 1: 1), and cement clinker as a binder, pellets were prepared in the same manner as in Example 1, and the curing strength was increased after 3 days according to the mixing ratio of these pellets. It measured and the result is shown in following Table 4. At this time, the sintered dust and the converter EC dust in a ratio of 1: 1 are used to meet the level of T.Fe = 60% by weight, which is practically similar to iron (T, Fe content) of iron ore. This is because the strength of the unadded dust pellets was similar to about 50% of the compressive strength of the iron ore blended material 1B added with the binder.

TABLE 4

As shown in Table 4 above, 15-16% by weight of the dust mixture and 15% by weight of the dust mixture were used as the standard formulation for Comparative Example (11). Even if it reduces from 2% by weight to 2% by weight, it will have the strength of the standard blending level of Comparative Example 11, but in the case of Comparative Example 23 in which 60% by weight of the dust mixture is added and 1% by weight of the binder is added. It was found that the strength was less than that of (11).

In addition, as in the case of the invention examples (13) and (15-22), it can be seen that the compressive strength corresponding to about 1% by weight of the cement clinker per about 15% by weight of the dust mixture.

That is, in the case of Comparative Example (14), compared with the reference Comparative Example (11), 3 wt% of the cement clinker as the binder was reduced from 5 wt% to 2 wt%, but the amount of the dust mixture was added to 15 wt%. Due to the small addition, it can be seen that the compressive strength of the pellet of Comparative Example 14 stayed at a level of 30.4 kg / piece lower than the compressive strength of 33.1 kg / piece of the Comparative Example 11.

On the other hand, as in the case of Comparative Example (23) it can be seen that the proportion that can replace the cement clinker by mixing the dust mixture as is usually about 60% by weight of the total raw material at the lower limit of the amount of the binder is added.

As described above, the present invention is a method for producing non-fired pellets mainly composed of iron ore for each production area and adding cements as binders, the cement being a binder of a mixture of sintered dust and converter EC dust produced by the steelmaking process. There is an effect of reducing the addition amount of the binder by replacing the, and the replacement effect of the dust mixture to replace the cement cement as a binder is equivalent to 1% by weight cement based on 15% by weight dust mixture.

Claims (2)

In the method for producing non-plastic pellets by adding 2-10% by weight of cement-based binder to the iron-containing raw material, the cement-based binder is partially added with a sintered dust and an EC dust mixture and replaced with the dust mixture. The addition ratio is at least 15% by weight per 1% by weight of the cement binder and 60% by weight or less based on the total blended raw material manufacturing method of the non-baking pellets, characterized in that. The method for producing non-fired pellets according to claim 1, wherein the dust mixture is a mixture of sintered dust and converter is dust 1: 1.