JPH0550456B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is a borosilicate alkali glass (B ₂ O ₃ −CaO−SiO ₂ −Na This invention relates to a slag pulverization inhibitor for ₂ O-based glass, a method for producing the same, and a method for using the same. [Prior art] Steelmaking slag, especially stainless steelmaking slag, with a basicity (CaO/SiO ₂ weight ratio) of approximately 1.5 or more changes from an α-type phase to an α′-type phase due to a phase transition of 2CaO・SiO ₂ during the cooling process. Furthermore, it has the property of transitioning to the γ-type or β-type, and in many cases, when the slag transitions from the α′ to the γ-type, it is accompanied by a volumetric expansion of about 14%, which causes the slag itself to disintegrate and become powder. It has been known. This pulverization phenomenon worsens the working environment, and problems such as the generation of a large amount of dehydrated cake as a residue after recovering the metal in slag have become a major cause of the increased burden on stainless steel manufacturers for slag processing. There is. To prevent this slag from turning into powder and solidify it,
Effective use of discharged slag as aggregate for civil engineering such as roads 2
This has been a long-standing challenge for stainless steel manufacturers, as it can be used for other purposes. Examples of methods for suppressing slag pulverization include the following methods. (1) A method of pulverizing and vitrifying slag during extraction. (2) Add SiO ₂ source to 2CaO・SiO ₂ slag and add CaO・
A method of reforming slag into a slag with a basicity of 1.5 or less (substantially varies depending on the slag composition), mainly composed of SiO ₂ . (3) A method of suppressing the phase transition from the α′ type to the γ type, which has a large density change, and promoting the phase transition from the α′ type to the β type, which has a small density change. In method (1), the molten metal accompanying the slag sludge may cause a steam explosion during granulation, and the granulated material is too soft to have sufficient strength to be used as aggregate for civil engineering. Although it has been experimentally tested in some areas, it has not yet been put into practical use. In method (2), some SiO ₂ -based modifiers are currently commercially available, but for molten slag approximately 20
Since it requires a large amount of SiO ₂ , such as
It is necessary to install stirring equipment, and the slag increases in viscosity due to a drop in temperature of the slag that accompanies addition, making it unsuitable in terms of workability and cost. Method (3), that is, the phase transition from α′ type to β type, has been studied for a long time, and ^various methods have been proposed. The method of replacing Si ⁺⁴ with B ⁺³ , which has a smaller ionic radius than that of ions, is currently proposed as the most effective and reliable method.
(Unexamined Japanese Patent Publication No. 1983-43690, Kawatetsu Technical Report Vol. 18, No. 1
(1986) 20-24) However, since such conventional boron-based slag pulverization inhibitors are in the form of fine powder and contain water themselves, when they come into contact with molten slag, they undergo dehydration and vaporization reactions. The slag pulverization inhibitor is blown up, which significantly deteriorates the working environment and is sometimes dangerous, making the operation extremely difficult. Furthermore, although the melting temperature of the slag pulverization inhibitor itself is low, since the viscosity is high, diffusion and mixing into the slag is insufficient due to slag sensible heat alone, and there is a problem that it is difficult to exhibit the slag pulverization prevention effect. In addition, because the chemical composition of conventional boron-based slag pulverization inhibitors is significantly different from that of slag, differences in viscosity and density tend to occur with respect to molten slag. The drawbacks are poor performance and low diffusion mixing ability. [Problems to be Solved by the Invention] In order to eliminate the conventional drawbacks of boron-based slag pulverization inhibitors, it is necessary to consider the following matters. (1) When added to the slag, the working environment should not be degraded due to dust generation, harmful gas generation, etc., and the operation should be safe. (2) The amount added to the slag should be small enough to avoid a significant drop in slag temperature and thickening. (3) It must have a chemical composition with a small difference in viscosity and density and a high affinity with molten slag. [Means for Solving the Problems] In view of the above-mentioned problems, the present inventors conducted extensive research on improving boron-based slag pulverization inhibitors and completed the present invention. That is, the present invention relates to a steelmaking slag pulverization inhibitor containing sandy powder of borosilicate alkali glass as an active ingredient, a method for producing the same, and a method for treating steelmaking slag using the same. The present invention will be explained below. The boron-based steelmaking slag pulverization inhibitor (hereinafter referred to as "slag pulverization inhibitor") according to the present invention is a sandy powder of borosilicate alkali glass, unlike the conventional crystalline borate compound powder. characterized by something. This glass is made from steelmaking slag (hereinafter simply "slag").
) has a better affinity with the molten material than crystalline boric acid compounds, but in order to improve the affinity, it is necessary to have a chemical composition that is similar in viscosity, specific gravity, etc. to molten slag. is desirable. Therefore, _the glass often has a chemical composition of _B2O3 : 20-50% by weight, CaO: 15-35% by weight,
_SiO2 : 20-40% by weight and _Na2O : 3-15% by weight
within the range of Outside this range, the viscosity becomes high or vitrification becomes difficult, and the performance of the anti-dusting agent tends to deteriorate. It goes without saying that the presence of unavoidably mixed impurities is naturally acceptable. Next, the glass pulverization inhibitor according to the present invention has a sand-like particle size distribution. The reason for this is that when added to molten slag, depending on the mode of addition, it can be added quickly with fluidity, suppress generation of dust, and provide rapid and stable melting properties. It is. In many cases, it is preferred that the particle size is at least 90% in the range 0.1 to 5 mm. The anti-dusting agent according to the present invention has the above-mentioned glass sand-like material as an active ingredient, and the active ingredient here refers to not only the glass sand-like material itself, but also the auxiliary agents described below. say something That is,
Depending on the manner in which it is added to the molten slag, smooth melting into the molten slag may be poor, and in some cases, unmelted lumps, so-called "mako", may be formed. Therefore, in order to promote good melting, diffusion and mixing effects in the molten slag immediately after the addition of the powdering inhibitor, an adjuvant may be added to the powdering inhibitor as required. Such adjuvants refer to powders that cause dehydration and/or decarboxylation reactions when heated;
Such powders include, for example, clays, activated clay, aluminosilicates such as diatomaceous earth, bentonite,
Aluminosilicate like zeolite, nacre,
limestone, bicarbonate of soda, sodium, potassium,
At least one or more selected from carbonates such as calcium, magnesium or barium, borates such as borax, carnite, ulexite, and colemanite. The amount of these adjuvants added varies depending on the method of adding the type of anti-dusting agent or the physical properties and condition of the molten slag, but it may be at most 30% by weight of the anti-dusting agent, and is preferably is 5-15% by weight
within the range of In addition, the particle size of this adjuvant is preferably smaller than the particle size of the dusting inhibitor in most cases, and it is preferable that the average particle size is below the lower limit of the dusting preventive agent. Next, the anti-dusting agent has a glass composition of B _2
O3 : 20-50% by weight, CaO: 15-35% by weight,
_SiO2 : 20-40% by weight and _Na2O : 3-15% by weight
After blending raw materials containing one or more of boron, calcium, silicon, and sodium so that the resultant mixture is heated and dissolved,
It can be manufactured by rapid cooling and particle size adjustment. Examples of boron raw materials include boric acid, chemical products such as sodium borate, colemanite (Ca ₂ B ₆ O ₁₁・5H ₂ O), and ulexite (NaCaB ₅ O ₉・8H ₂ O) as described above. ), tincal (Na ₂ B ₄ O ₇ .10H ₂ O), and kernite (Na ₂ B ₄ O ₇ .4H ₂ O). Calcium raw materials include limestone, slaked lime, quicklime, calcium silicate, etc. Silicon raw materials include silica stone, silica sand, silica, aluminum silicate, calcium silicate, etc. Sodium raw materials include soda ash, sodium silicate glass, etc. It will be done. These raw materials are appropriately selected and blended so that the glass composition falls within the above range, and the glass is charged into a desired melting furnace and heated and melted. Next, the melt is rapidly cooled and the particle size is adjusted to obtain a product. As a method for rapidly cooling the melt,
In many cases, the most practical and preferred method is to crush the melt by applying pressure water to it while tapping it and collect it as sand-like glass, but other methods include:
There is a method in which the tapped melt is placed on a belt conveyor, cooled with water or air, and collected as cullet. Next, the particle size is adjusted after drying to remove adhering water, but in the case of granulated products, particle size adjustment by crushing and sieving is not necessarily necessary, and the dried product can be made into a product as it is, so viscosity adjustment is not necessary. You can do it accordingly. In this case, the above-mentioned auxiliary materials may be added if desired. Furthermore, the present invention provides that when the anti-pulverization agent is used, in the steel manufacturing process, particularly in the stainless steel manufacturing process,
Powdering of the slag can be prevented by adding a sandy powder containing borosilicate alkali glass as an active ingredient to the by-produced molten slag in an amount of at least 0.2% by weight as B ₂ O ₃ . The slag targeted in the present invention is steel manufacturing slag such as stainless steel, but the slag tends to disintegrate or powder when cooled or due to changes over time, and generally has a basicity of CaO/ SiO ₂ (weight ratio) is 1.5 or more. Further, the manner in which the anti-pulverization agent according to the present invention is added is not particularly limited as long as it can be mixed and diffused into the molten slag immediately after addition. Examples include a method of spraying it on the surface of the molten slag, a method of adding it to each bag containing the desired amount, and a method of adding it to the molten slag by transferring it with pressurized air and spraying it onto the molten slag. The amount of the anti-dusting agent according to the present invention added to the slag is at least 0.2 as B ₂ O ₃ as described above.
% by weight, preferably in the range of 0.3 to 1% by weight. If it is less than about 0.2% by weight, it is insufficient to prevent slag pulverization, and the upper limit is naturally limited mainly for economic reasons. The present invention will be specifically explained below with reference to Examples. [Example] Example 1 The following blending ratio (parts by weight) of the raw material blend
It was melted using a resistance electric furnace with a capacity of 100KVA.

[Table] The obtained melt was crushed and dried to prepare the following crushed vitrified product having the following composition (wt%). This product was sealed in a plastic bag weighing 10 kg each and used as a powdering prevention agent test sample.

[Table] Yes.
Furthermore, the basicity (CaO/
SiO ₂ = 1.62) When removing slag from a ladle into a slag pot, 60 kg of a 10 kg test sample was put into a plastic bag at the same time, and the slag was allowed to cool and solidify, and then the situation was observed until it reached room temperature. The conditions during the test were as follows.

[Table] In these experiments, the amount of the test sample added to the molten slag was 0.43B ₂ O ₃ % by weight in Test No. 1, 0.45B ₂ O ₃ % by weight in Test No. 2, and 0.46% in Test No. 3.
Corresponds to % by weight. During the sample addition, no dust or gas generation was observed in any of the experiments, the addition operation was safe, and good diffusion mixing was obtained when the slag was poured into the slag pot. Furthermore, after cooling the slag during the test to room temperature,
When the situation was observed, no disintegration and powdering phenomenon was observed. The slag composition (weight %) after the test was as follows.

[Table] Note that this slag itself self-disintegrates and becomes powder when cooled. In addition, the slag disintegration rate of samples A, B, and C with added samples (after modification) and slag without additives (before modification) was subjected to autoclave treatment under the following treatment conditions. Processing conditions: After crushing the sample slag, adjust the particle size to 10 to 25 mm, hold it in an autoclave at 200℃, 20 Kg/cm ² for 3 hours, then dry and sieve, disintegrating particles with a particle size of less than 10 mm. I made it into a thing. The ratio (%) of the disintegrated material after the above autoclave treatment is shown.

[Table] Example 2 Samples A, B, and C used in Example 1 to see the effect of using bound water and carbonate together
Add and mix activated clay (particle size 1 to 2 φmm), limestone (particle size 1 to 2 φmm), or sodium bicarbonate (powder) in the proportions shown in the table below, and seal the test sample in a 10 kg plastic bag. And so. This sample was tested in the same manner as in Example 1. The conditions during the test were as follows.

[Table] The slag composition analysis values (weight %) during the test are generally as follows.

[Table] In all experiments, no dust generation phenomenon was observed when the sample was introduced.Due to the dehydration and decarboxylation reactions, the sample instantly scattered and flowed on top of the molten slag, and rapidly melted into the slag. It spread. When the slag during the test was allowed to cool to room temperature and then observed, no disintegration and powdering phenomenon was observed, and the amount of powdering inhibitor used for the slag was 0.30 to 0.37B ₂ O ₃ % by weight, which was sufficient to achieve sufficient effect. It turns out that it can be raised. Comparative Example In Example 1, borax (Na ₂ B ₄ O ₇・10H ₂ O) (B ₂ O ₃ :
When 12 kg/t of slag (37.00 wt%, Na ₂ O: 16.5 wt%) (55% of which is 0.2 to 0.4 mm) was added to each plastic bag, violent scattering and blowing occurred, resulting in undissolved lumps. Therefore, we had no choice but to cancel the injection. [Effects of the invention] 1 Since the product of the present invention is a vitrified slag pulverization inhibitor, the amount of heat absorbed due to melting such as the thermal decomposition heat of vaporization of carbon dioxide gas, water vapor, heat of transition, etc. is small, and the melting rate is low. Extremely fast compared to conventional ones. 2. Since the chemical composition is designed to have a high affinity for molten slag with small differences in viscosity, density, etc., the product of the present invention has an extremely large diffusion-mixing effect compared to conventional products. Furthermore, when a substance that undergoes a dehydration or decarboxylation reaction upon melting is mixed with the product of the present invention, the diffusion and mixing effects are significantly improved compared to when mixed with a conventional product. 3. Because it is a vitrified slag powder prevention agent,
Since it does not cause a degassing reaction and has a sand-like size, it does not deteriorate the working environment due to flying dust when added to molten slag.

Claims (1)

[Scope of Claims] 1. An agent for preventing powdering of steelmaking slag, which contains sandy powder of borosilicate alkali glass as an active ingredient. 2 The chemical composition of borosilicate alkali glass
_B2O3 : 20-50% _by weight, CaO: 15-35% by weight,
_SiO2 : 20-40% by weight and _Na2O : 3-15% by weight
The steel-making slag pulverization inhibitor according to claim 1, which contains the following. 3. The steel-making slag pulverization inhibitor according to claim 1, which contains, as another component, at most 30% by weight of powder that causes dehydration and/or decarboxylation reaction upon heating. 4 The sand-like powder of borosilicate alkali glass has a particle size of
The steelmaking slag pulverization inhibitor according to claim 1 or 2, wherein 90% or more of the agent has a particle size in the range of 0.1 to 5 mm. 5 _B2O3 : 20-50% _by weight as glass composition,
Raw materials containing one or more of boron, calcium, silicon, and sodium are mixed so that CaO: 15 to 35% by weight, SiO ₂ : 20 to 40% by weight, and Na ₂ O: 3 to 15% by weight. A method for producing a powdering inhibitor for steelmaking slag, which comprises heating and melting the resulting mixture, followed by rapid cooling and particle size adjustment. 6. A method for producing a powdering inhibitor for steelmaking slag according to claim 5, which comprises blending a powder that causes dehydration and/or decarboxylation upon heating into the glass sandy powder obtained by drying. 7 Powders that cause dehydration and/or decarboxylation reactions upon heating include clays, aluminum silicates such as activated clay, aluminosilicates such as bentonite and zeolite, nacre, limestone, carbonates such as sodium bicarbonate, sodium, calcium, magnesium, or barium. , borax, carnite,
The method for producing a powdering inhibitor for steel slag according to claim 6, wherein the powder is one or more powders selected from borates such as ulexite and colemanite. 8. Adding sand-like powder containing borosilicate alkali glass as an active ingredient to molten slag, which is a by-product of the steelmaking process.
A method for preventing pulverization of steelmaking slag, which comprises adding B ₂ O ₃ in an amount of at least 0.2% by weight.