JPH062610B2 - Slag treatment agent - Google Patents

Description

TECHNICAL FIELD The present invention relates to a slag treating agent for modifying iron-making slag and steel-making slag. More specifically, the present invention relates to a modified slag treating agent which is effective in preventing turbid water generated by pulverization or self-disintegration or contact with water in the cooling process of steelmaking slag such as blast furnace slag or steelmaking slag.

[Prior Art] Steelmaking slag, especially stainless steelmaking slag,
Slag with a basicity (CaO / SiO ₂ weight ratio) of about 1.5 or more,
In the cooling process, it has the property of transforming from α-type phase to α'type, and then to γ-type or β-type due to the phase transition of 2CaO · SiO ₂ , and in many cases, when it changes from α'to γ-type, about 14%
It is known that the slag itself self-disintegrates and powders due to the volume expansion of the.

This pulverization phenomenon deteriorates the working environment, and the problem that a large amount of dehydrated cake as a residue after recovery during metal recovery in slag is a major cause of increased burden on stainless steel manufacturers for slag treatment. ing.

Preventing the slag from pulverizing and solidifying it has been a long-standing problem for stainless steel manufacturers because the discharged slag can be effectively used as a secondary aggregate for civil engineering such as roads.

The following methods are mentioned as a method of suppressing slag pulverization.

Method for granulating vitrified glass when slag is discharged; 2CaO ・ SiO ₂ slag with SiO ₂ source added, with CaO ・ SiO ₂ as the main component having a basicity of 1.5 or less (substantially varying depending on the slag composition) A method of modifying into slag; a method of suppressing the α′-type to γ-type phase transition having a large density change and promoting the α′-type to β-type phase transition having a small density change.

In the method described above, the molten metal that accompanies the slag slag may cause a steam explosion during water granulation, and the granulated material may not have sufficient strength for use as an aggregate for civil engineering due to its softness. Although some have been experimentally tested, the current situation is that they have not been put to practical use.

Some of the methods are currently marketed as SiO ₂ -based modifiers, but a large amount of Si, about 20% of the molten slag, is used.
Since O ₂ is required, it is necessary to install charging equipment and stirring equipment, and further increase the viscosity of the slag due to the temperature decrease of the molten slag accompanying the addition, which is unsuitable in terms of workability and cost.

, That is, the phase transition from α'type to β type has been studied for a long time and various methods have been proposed. Among these methods, Si in slag is included.
^The method of substituting Si ⁴⁺ with B ³⁺ having a smaller radius than ⁴⁺ ion has been proposed as the most effective and reliable method at present [Japanese Patent Laid-Open No. 53-43690, Kawatetsu Technique Vol. 18,
No. 1 (1986) 20-24].

However, since the conventional boron-based slag dusting inhibitor is in the form of fine powder, and is itself a water-containing substance, it is coupled with a dehydration vaporization reaction when it comes into contact with molten slag, and causes a blowing-up phenomenon of the slag dusting inhibitor. And the working environment is significantly deteriorated, and at the same time, it is dangerous, which makes the operation very difficult.

Further, the conventional boron-based slag dusting inhibitor, because the chemical composition and physical properties are significantly different from the slag, relative to the molten slag, viscosity, density is likely to cause a difference, so-called slag and slag dusting inhibitor However, it has a drawback in that it has a poor affinity and a small diffusive mixing ability, and despite the proposals so far, it cannot be used in actual operation.

Secondly, as a problem of steelmaking slag such as blast furnace slag or steelmaking slag, there is generation of so-called yellow turbid water generated when water and slag come into contact with each other, such as rainwater and drowning water.

As is well known, blast furnace slag and the like are widely used as various aggregates, especially roadbed materials. However, when the sulfur content in these slags is high, it has been confirmed that if the usage conditions and usage methods are incorrect, rainwater contacting the slag, turbid water, and the like, causing cloudy water of sulfur compounds and hydrogen sulfide odor, Particularly for road slag applications, in order to secure products that do not have such a risk of damage, the slag must be one that does not generate yellow turbid water or hydrogen sulfide odor as a standard for road slag, and the color determination test is It is adopted as a confirmation method, and it is stipulated that it should be passed (JIS A 5015: Announced on November 1, 1985).

The phenomenon of cloudy water generation is due to the elution of sulfur (S) contained in the form of calcium sulfide (CaS) mainly contained in slag, and the yellow polysulfide (for example, CaS
It is considered that x) is generated, and the following method, for example, is known to prevent the generation of turbid water.

A method of oxidizing and stabilizing slag with water and air by aging; a method of adding an oxidant to molten slag; a method of treating slag with CO ₂ to stabilize the slag surface; a method of increasing the cooling rate of slag .

Since the method of (1) requires a period of about 1 to 3 months for aging treatment, a vast storage space is required.

Examples of the method include a method of adding a high-order iron oxide into the molten slag and a method of introducing a gas containing oxygen, for example, air.
_{Since 2} occurs, it is not a safe method,
In addition, the current situation is that the generation of cloudy water has not been completely prevented.

In the method of, the slag surface is stabilized,
When used as a crow, if it is crushed during rolling, it has the drawback that sulfides will be re-eluted from the fracture surface.

The method of is a method of forming a glassy material by rapidly cooling the molten slag into granules, and preventing leaching of the content of sulfur, but deterioration of strength is unavoidable, and in order to form a glassy material. There is a problem in that it is necessary to granulate to have a characteristic viscosity or less, and although it can be used for fine aggregates, it is difficult to use for coarse aggregates.

From the above, the actual situation is that slag aging is the only method currently available for preventing slag from becoming muddy water.

[Problems to be Solved by the Invention] As is clear from the above, the present invention is industrially inexpensive because of the pulverization phenomenon and the generation of turbid water, which have been problems of steelmaking / steelmaking slag for many years. At the same time, a simple slag treating agent is intended to be solved.

Therefore, the object of the present invention is to improve the conventional boron-based powdering inhibitors to more effectively promote the substitution reaction of Si ⁴⁺ and B ³⁺ to improve the slag all at once. It is to try to solve the problem.

[Means for Solving the Problems] In view of the above problems, the present inventors have conducted earnest research on improvement of a boron-based slag dusting inhibitor, and completed the present invention.

That is, the present invention relates to a slag treating agent characterized by being a glass article containing boron as an active ingredient, and having a particle size distribution in the range of 5 to 30 mm is 90% or more of a coarsely crushed material.

[Operation] The present invention will be described below.

The slag treatment agent according to the present invention is different from the hydrous crystalline borate powder conventionally known as a powdering inhibitor for steelmaking slag, and is characterized in that it is a glass body coarsely pulverized product of a substance containing boron as an active ingredient. There is.

The affinity of the slag mainly composed of basic calcium silicate (hereinafter simply referred to as "slag") in iron making or steel making for the melt is crystalline alkali borate which is a precursor of the glass according to the present invention. It is far superior to salt compounds, and even with its slag, homogenization with slag,
It gave favorable results that exceeded our expectations.

The substance containing boron as an active ingredient is preferably one having a relatively high boron content due to its nature, and in many cases, it is about 10% by weight or more, preferably about 20% by weight or more as B ₂ O _3. belongs to.

As such a substance, for example, natural or synthetic alkali borate, alkaline earth metal borate, those mainly composed of two-component borate such as borosilicate, alkali borosilicate, alkaline earth borosilicate metal salt Those mainly composed of ternary borosilicates such as, or boron, silicon,
Representative examples include those containing four components of alkali metal and alkaline earth metal as main compositions.

Further, a substance containing boron as an active ingredient means that the above ingredient is contained in the glass as at least 80% by weight or more, and in this case, as B ₂ O ₃ , at least 10% by weight or more, preferably 20% by weight or more as an active ingredient. It is contained.

Therefore, other components are acceptable up to 20% by weight at most, but the components are unavoidably mixed in for the reason of manufacturing the glass body of the substance containing boron as an active ingredient, or the physical properties of the substance, for example, glass. It can be fixed as a sulfide or a component for adjusting physical properties such as melting point, softening point, viscosity and surface tension.

Examples of such components include Fe ₂ O ₃ , Ml ₂ O ₃ , MnO ₂ , ZnO, F and the components contained therein.

In the above, as a substance containing alkali borate as a main component, the following general formula Me ₂ O · nB ₂ O ₃ (wherein Me is Li, K,
Representing at least one kind or two or more kinds of alkali metal elements selected from Na, n represents a range of the number of moles of 1 to 10), and the main composition is an alkaline earth metal borate salt. As the substance, the following general formula MeO.nB ₂ O ₃ (in the formula,
Me represents at least one or more alkaline earth metal elements selected from Mg, Ca, Ba or Sr, and n
Represents a range of 1 to 5 moles), and as a substance mainly composed of borosilicate, the following general formula SiO ₂ · nB
₂ O ₃ (wherein n represents the range of the number of moles of 1 to 9), B ₂ O ₃ having a main composition of alkali borosilicate: 10 to 80% by weight, SiO ₂ : 5 to 70% by weight,
Me ₂ O: in the range of 2 to 50% by weight and in the range of 0 to 20% by weight, B ₂ O ₃ : 20 to 80% by weight and SiO ₂ : 10 as a composition mainly composed of alkaline earth metal borosilicate. ~
60% by weight, MeO: 5 to 40% by weight and others 0 to 20
A weight percent range, and a boron-containing material of the four-component system as the main composition is B ₂ O _3: 20~60 wt%, SiO
₂ : 5 to 40% by weight, Me ₂ O: 3 to 40% by weight, MeO: 1
Practically preferred is in the range of 0 to 40% by weight.

The reason for this is that glass containing boron as an active ingredient must be rapidly dissolved and diffused in the molten slag, but the boron-containing substance of the above composition of the present invention has a melting point or softening point of about 1100 ° C. or less, preferably 700-1050 ° C
It is in the range of, at the temperature of the molten slag,
This is because the composition is such that it can be easily dissolved and diffused.

Here, the glass is a substance obtained by melting and cooling a substance containing boron as an active ingredient, which is amorphized to the extent that it cannot be clearly identified by a specific diffraction line intensity in X-ray diffraction analysis. .

The vitrified product of the substance containing boron as an active ingredient is crushed and used, but it needs to be a crushed product.

Therefore, the particle size distribution in the range of 5 to 30 mm is 90% or more.

The treatment agent according to the present invention can be used in combination with an auxiliary agent, if necessary. That is, depending on the mode of addition to the molten slag, the smooth melting into the molten slag may be inferior, and sometimes an insoluble mass, so-called “mamako” may occur.

Therefore, after the addition of the slag treating agent, an auxiliary agent can be added to the slag treating agent, if necessary, in order to promote rapid dissolution, diffusion and mixing effects in the molten slag.

Such an auxiliary agent refers to a powder that causes a dehydration and / or decarboxylation reaction by heating, and examples of such a powder include clays, activated clay, aluminosilicates such as diatomaceous earth, bentonite, and aluminosilicates such as zeolites, At least one selected from pearlite, limestone, sodium bicarbonate, carbonate such as sodium, potassium, calcium, magnesium or barium, and borate such as borax, carnite, urexite and colemanite may be used, or two or more thereof may be mentioned.

The amount of these auxiliaries added is not uniform depending on the type, the addition method of the pulverization preventing agent, the physical properties and the state of the molten slag, but at most 30% by weight based on the pulverization preventing agent, preferably 5 Is in the range of up to 15% by weight.

In many cases, the particle size of this auxiliary agent is preferably smaller than that of the anti-dusting agent, and its average particle size is preferably below the lower limit value of the anti-dusting agent.

The slag treating agent according to the present invention can be produced by blending a raw material containing a substance containing boron as an active ingredient, then heating and melting the resulting formulation, followed by cooling and crushing.

Boron raw materials such as boric acid as described above, chemical products such as sodium borate or colemanite (C
_{a 2 B 6 O 11 · 5H} 2 O), ulexite _{(ulexite) (NaCaB 5 O 9} · 8H
₂ O), tincal (Na ₂ B ₄ O ₇・ 10H _{H 2} O), carnite
Examples thereof include borate minerals such as (Kernite) (Na ₂ B ₄ O ₇ · 4H ₂ O), and examples of the alkali raw material include caustic alkali, alkali carbonate, alkali bicarbonate and the like. Alkaline earth metal raw materials include alkaline earth metal carbonates, hydroxides and oxides, and silicon raw materials include silica sand, silica rock, diatom, synthetic silica, slag,
Examples include clays. Other raw materials include Fe ₂ O ₃ ,
Examples thereof include Al ₂ O ₃ , MnO ₂ , fluorides and substances containing them.

These raw materials are appropriately selected and compounded so that the glass composition falls within the above range, and the mixture is put into a desired melting furnace and heated and melted. Next, the melt is cooled and then the particle size is adjusted to obtain a product.
In many cases, the most practical and preferable method of cooling the melt is to tap the melt and apply pressured water to the melt to granulate it and collect it as sandy glass. As another method, there is a method in which the melt to be tapped is placed on a belt conveyor and cooled with water or air to recover it as cullet.

Next, the particle size is adjusted after drying to remove the adhered water.However, in the case of a granulated product, the particle size adjustment by crushing and sieving is not always necessary, and the dried product can be directly used as a product. It can be done as needed.

In this case, if desired, the above-mentioned auxiliary agents can be added.

The slag to be used in the present invention is mainly a slag that causes a phenomenon of disintegrating or pulverizing upon cooling or aging, or a basic calcium silicate that causes so-called turbid water to be generated when contacted with water. A slag having a composition, generally having a basicity (CaO / SiO ₂ weight ratio) of at least 1.3, usually in the range of 1.5 to 3.5, such as blast furnace slag and stainless steel. Examples of the steelmaking slag or converter slag.

Amount added for slag Surak treatment agent according to the present invention is not uniform depending on the composition and physical properties, or slag composition, etc., at least about as B ₂ O ₃ in any of the purposes of the powdering prevention and yellow cloudy inhibiting water slug Although it is 0.15% by weight, considering the durability of the modified slag, it is preferably 0.3% by weight or more.

The reason for this is that if it is less than about 0.15% by weight, it is insufficient to prevent turbid water and pulverization. On the other hand, although the upper limit need not be particularly limited, it is mostly for economic reasons or for hot metal. It is of a nature that is naturally limited in consideration of its influence. Therefore, 0.3 to 1.5% by weight as B ₂ O ₃ is a practically preferable range.

When modifying the slag using the slag treating agent according to the present invention, without changing the operating conditions of the conventional blast furnace or steelmaking furnace, in the conventional operating process, the presence or absence of hot metal into the molten slag Add slag treating agent.

Therefore, for example, when tapping from a blast furnace through a gutter, an input port is provided at a desired position of the gutter, and when adding from this, when the molten slag is removed by a slag wheel etc. by a weir provided in the gutter, Alternatively, the slag treating agent is added when tapping with a molten slag to a torpedo car or the like.

Further, the same applies to the case of making steel such as stainless steel, and when removing molten stainless steel pig from the melting electric furnace to the ladle or when removing molten slag from the ladle to the slag pot, a slag treatment agent. Is added.

In this case, the mode of addition of the slag treating agent to the molten slag is not particularly limited as long as it adopts a method in which the slag treating agent is quickly dissolved and diffused in the slag.

For example, the molten slag in the presence or absence of hot metal, the slag treating agent, the method of adding as it is, the method of adding together with air pressure, the method of adding by adding as a packaging bag, or the slag hot water in the presence of the slag treating agent in advance. And the like.

Even if the slag treating agent is added in the presence of hot metal, the influence of boron mixed in the hot metal is so small that it is practically negligible in many cases.

Therefore, addition of slag treated is performed when slag pot etc. are removed, only when the above influence is considered,
In other cases, since the viscosity of the slag melt is smaller if it is carried out in the slag in the presence of hot metal held at a high temperature, the slag treating agent is dissolved and diffused quickly, so that the slag is uniformly modified. It is rational.

When added to the slag pot or the like, if the viscosity of the slag melt becomes high and the dissolution / diffusion of the slag treating agent may become insufficient, reheating or diffusion of the slag is promoted as necessary. The above-mentioned auxiliary agents can be used in combination.

However, after adding the slag treating agent to the molten slag, it is substantially unnecessary to provide a special diffusion means for prompt dissolution and diffusion.

Therefore, after the addition, the modified slag can be obtained by slow cooling or rapid cooling by a conventional method.

[Examples] The present invention will be further described with reference to Examples.

Example 1 Preparation of slag treating agent sample: Raw material blends having the following blending ratios (parts by weight) were melted in an electric furnace, and the resulting melt was rapidly cooled in a steel water-cooled pan to coarsely crush the vitrified product. By doing so, a glass cullet having a size of 5 to 30 mm was prepared.

The particle size distribution of glass cullet is 9 for 5 to 30 mm.
It was 0% or more.

The main compositions of the samples Nos. 1 to 8 are described below.

The chemical components (% by weight) of Sample Nos. 9 to 17 obtained in the same manner are as shown in the table below.

Slag dusting prevention test: Slag basicity (CaO / SiO ₂ = 2.1) at the first tapping produced from an electric furnace for stainless steel (30 ton capacity)
0) When removing the slag from the ladle to the slag spot, 53 kg of the plastic bag containing 10 kg of the test sample of each slag treating agent obtained above was simultaneously put into the slag spot, and the slag was left to cool and solidify. The conditions up to room temperature were observed.

The conditions during the test are as follows.

When adding each sample, no dust or gas was observed in any of the experiments, the addition operation was safe, and good diffusion mixing was obtained when pouring slag into the slag spot.

When each slag tested was allowed to cool to room temperature and then observed, the test Nos. 1 to 17 showed no disintegration and pulverization.

On the other hand, the normal slag of Test Nos. 18 to 20 with no added slag treating agent self-disintegrated and powdered when cooled.

The slag composition analysis value (wt%) at the time of the test is generally as follows.

Test No. CaO SiO ₂ MgO Al ₂ O ₃ 1-20 48-55 22-28 9-13 9-15 In any of the experiments, no dusting phenomenon due to sample injection was observed, and the sample was instantaneous on the molten slag. After scattering and flowing inside, and observing the situation after allowing the slag to cool to room temperature, the phenomenon of disintegration pulverization was not seen at all, and the amount of the pulverization inhibitor used was 0.46-0.53B ₂ O. It was found that a sufficient effect can be obtained with ₃ % by weight.

Example 2 The same slag treating agent 9 as that used in Example 1 was added to molten slag in tapping produced from an electric furnace in a predetermined amount when the slag pot was removed from a ladle as a plastic bag.
After this treatment, the molten slag undergoes normal standing cooling and MS-
The particle size was adjusted to a particle size range equivalent to 25 to obtain a ballast.

The presence or absence of yellow turbid water in the obtained ballast was measured by the following evaluation method. Measurement results and chemical composition of slag (% by weight)
Is shown in Table 5 below.

Evaluation method of turbid water 500 g of the obtained sample ball was weighed, put in 1500 ml of pure water, boiled for 45 minutes according to the color determination test of JIS A 5015, and the elution water liquid was collected in a colorimetric tube, The color standard solution made of potassium dichromate is visually compared to determine "color presence" or "no color". That is, in order to quantify the shade of the color of this eluted water, that is, the degree of hue, the absorbance of the standard solution and the eluted water was measured with an absorptiometer to measure
The yellow index as shown in the table is obtained and evaluated.

Example 4 The same slag treating agents 1, 3, 12 and 15 as used in Example 1 for molten slag in tap iron produced from an electric furnace
When removing the slag pot from the ladle as it is in a plastic bag, B
0.40 wt% was added in terms of ₂ O ₃ . The molten slag that had been subjected to this treatment was subjected to normal standing cooling and then adjusted to a particle size range equivalent to MS-25 to obtain a ballast.

When the ballasts obtained by treating with the respective treatment agents were tested for cloudy water in the same manner as above, no cloudy water was observed in any of the ballas.

[Effects of the Invention] Since the slag treating agent according to the present invention is a glass body crushed product, it does not cause a degassing reaction such as carbon dioxide or water vapor when dissolved in a slag melt, and deteriorates the work environment due to blow-up and scattering. There is nothing to do.

Further, for the same reason, there is substantially no heat absorption amount due to melting such as heat of vaporization of vaporization, heat of transition, etc., and the crushed glass body is rapidly dissolved in the slag.

Diffusion after dissolution in slag can be adjusted as necessary by using an auxiliary agent together.

The slag treating agent according to the present invention can prevent powdering of slag produced as a by-product during iron making and steel making, and at the same time substantially prevent cloudy water.

According to the method of the present invention, such as a vinyl chloride resin bag containing a slag treating agent, a so-called poly bag or a paper bag can be simply charged into the molten slag without changing the conventional process, which is industrially very difficult. Is advantageous to.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takashi Fukuzawa 2-25 Matsuki-cho, Koriyama-shi, Fukushima Prefecture Koriyama Plant Co., Ltd. (72) Kosuke Takeuchi 2-25 Matsuki-cho, Koriyama-shi, Fukushima Nippon Chemical Industry Co., Ltd. Koriyama Plant (72) Inventor Tatsushi Tabata 2-25 Matsuki-cho, Koriyama-shi, Fukushima Nippon Chemical Industry Co., Ltd. Koriyama Plant

Claims (6)

[Claims] 1. A slag treating agent, which is a glass article containing boron as an active ingredient, and having a particle size distribution in the range of 5 to 30 mm is a crushed product of 90% or more. 2. The slag treating agent according to claim 1, wherein the glass has an alkali borate as a main composition. 3. The slag treating agent according to claim 1, wherein the glass has an alkaline earth metal borate as a main composition. 4. The slag treating agent according to claim 1, wherein the glass mainly comprises borosilicate. 5. The slag treating agent according to claim 1, wherein the glass has a main composition of alkali borosilicate. 6. The slag treating agent according to claim 1, wherein the glass mainly contains an alkaline earth metal borosilicate.