JP2020132456A - Aging method of slug, manufacturing method of civil engineering material, and hydration accelerator for aging treatment of slug - Google Patents

Abstract

To provide an aging method of slug capable of shortening an aging treatment for expansion suppression of the slug, by effectively accelerating hydroxylation (hydration) of the slug, when aging treating the slug containing free CaO or free MgO.SOLUTION: An aging treatment for hydrating free CaO and/or free MgO is performed with a hydration accelerator made of at least one or more kinds of hydration accelerators selected from NaOH, KOH, NHcontacted with the slug containing free CaO and/or free MgO. Due to the hydration accelerator working as a catalyst, the hydroxylation (hydration) of the free CaO and/or free MgO in the slug can be effectively accelerated to be able to shorten an aging interval.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for aging slag containing free CaO and free MgO, such as steelmaking slag.

Steelmaking slag is widely used as a civil engineering material such as a roadbed material and an earthwork material, and is also used as an aggregate of a hydrated hardened body. In the steelmaking slag produced as a by-product in the steelmaking process, a part of the lime source and magnesia source added in the refining process remains unmelted or freed without forming a compound with other components. When such steelmaking slag is used as a civil engineering material, it may expand due to hydroxylation (hydration) or carbonation of free CaO or free MgO, causing problems such as destruction of surrounding structures. In addition, since free CaO and free MgO become alkaline when they come into contact with water, there is a risk that the pH of the surrounding environment will increase due to the highly alkaline water eluted from the steelmaking slag.

Therefore, in order to use steelmaking slag as a civil engineering material such as roadbed material and earthwork material, it promotes hydroxylation (hydration) and carbonation of free CaO and free MgO contained in the slag and stabilizes it before use. It is necessary to suppress expansion and elution of highly alkaline water when using slag. For this reason, steelmaking slag before use is generally subjected to aging treatments such as atmospheric aging, steam aging, and hot water aging for the purpose of suppressing expansion (for example, Patent Documents 1 and 2). Further, for the purpose of suppressing expansion and elution of highly alkaline water, there is also a method of blowing a CO _2- containing gas into steelmaking slag to carbonate free CaO and the like (for example, Patent Document 3).

Regarding the conditions for steel slag used as roadbed materials, for example, "Steel slag roadbed design and construction guidelines" (March 2015) and JIS A5015 (2018) "Road steel slag" include roadbeds using steel slag. The water immersion expansion ratio of steel slag (water-hard grain size adjusted steel slag, grain size adjusted steel slag, crusher run steel slag) must be 1.0% or less, and the steel slag used for roadbed steel slag is steam aging (piping). Method, pressurization method, etc.) or that it must be air-aged for 6 months or more.

Japanese Unexamined Patent Publication No. 61-101441 Japanese Unexamined Patent Publication No. 3-13517 Japanese Unexamined Patent Publication No. 2005-200234

However, the effect of the conventional aging treatment depends only on the temperature (steam, hot water, atmospheric temperature) and the aging period, and the aging treatment can be used to suppress the expansion of steelmaking slag and the elution of highly alkaline water. There is a problem that long-term treatment is required and productivity is low. For example, steam aging takes about one week, and atmospheric aging takes six months or more. Further, the carbonation treatment requires a large agitator and gas sealing measures, so that there is a problem that the equipment burden is large.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and to perform aging treatment of slag containing free CaO and free MgO such as steelmaking slag without requiring a special equipment burden. By effectively promoting the hydroxylation (hydration) of free CaO and free MgO in the slag, the aging treatment for suppressing the expansion of the slag (reducing the water immersion expansion ratio) can be performed in a short period of time. By providing a method for aging slag and effectively promoting hydroxylation (hydration) + carbonation of free CaO and free MgO in slag, slag expansion is suppressed (reduction of water immersion expansion ratio). An object of the present invention is to provide a slag aging method capable of performing an aging treatment for suppressing elution of highly alkaline water from slag (reducing the pH of slag elution water) in a short period of time.

As a result of repeated experiments and studies on aging treatment of slag containing free CaO and free MgO in order to solve the above problems, the present inventors have conducted free CaO and free CaO in a state where a specific hydration accelerator is in contact with the slag. By performing the aging treatment (hydration treatment) to hydrate the free MgO, the hydroxylation (hydration) of the free CaO and the free MgO in the slag can be effectively promoted, and the expansion of the slag can be suppressed. We found that the aging period could be shortened. In addition, after performing such a hydration treatment or in parallel with the hydration treatment, an aging treatment (carbonation treatment) is performed in which the hydrate is carbonated in a state where the slag is in contact with a specific carbonation accelerator. By doing so, it is possible to effectively promote hydroxylation (hydration) + carbonation of free CaO and free MgO in slag, and shorten the aging period for suppressing slag expansion and elution of highly alkaline water. I found that it can be transformed.

The present invention has been made based on the above findings, and has the following gist.
[1] The free CaO and / or the free CaO and / or the free CaO and / or the slag containing the free MgO are brought into contact with the slag containing one or more selected from NaOH, KOH, and NH _3. Alternatively, a method for aging slag, which comprises performing an aging treatment for hydrating free MgO.
[2] The slag aging method according to the above [1], wherein the aging treatment is hot water aging.
[3] In the aging method of the above [2], when a plurality of lots of slag are sequentially aged, the solution used for hot water aging of one lot of slag is used for hot water aging of the slag of the next aging treatment. A slag aging method characterized by its use.

[4] relative to the free CaO and / or free MgO slag containing, NaOH, KOH, being in contact one or more consisting of wettable accelerator selected from the group consisting of NH _3, the free CaO and / Alternatively, in the step (A) of performing an aging treatment for hydrating free MgO,
In a state where the slag containing the hydrate of CaO and / or MgO that has undergone the step (A) is brought into contact with a carbonation accelerator composed of one or more selected from carbonates and bicarbonates. A method for aging slag, which comprises a step (B) of performing an aging treatment for carbonating the hydrate.

[5] The slag aging method according to the above [4], wherein the carbonate used in the step (B) is at least one selected from sodium carbonate, ammonium carbonate, and potassium carbonate.
[6] In the aging method of the above [4], the hydrogen carbonate used in the step (B) is one or more selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, and potassium hydrogen carbonate. Aging method.
[7] The slag aging method according to any one of the above [4] to [6], wherein the aging treatment in the step (A) is hot water aging.

[8] In the aging method of the above [7], when a plurality of lots of slag are sequentially aged, the solution used for hot water aging of one lot of slag in the step (A) is then aged. A slag aging method characterized by being used for hot water aging of slag.
[9] The slag aging method according to any one of the above [4] to [8], wherein the aging treatment in the step (B) is hot water aging.

[10] In any of the aging methods [4] to [9] above, CO ₂ is blown into slag or warm water in which slag is immersed during and / or after the aging treatment in step (B). A method of aging slag, which comprises regenerating a carbon dioxide accelerator.
[11] In the aging method of the above [10], when a plurality of lots of slag are sequentially aged, the solution used for hot water aging of one lot of slag in the step (B) is then aged. A slag aging method characterized by being used for hot water aging of slag.

[12] relative to the free CaO and / or free MgO slag containing, NaOH, KOH, being in contact one or more consisting of wettable accelerator selected from the group consisting of NH _3, the free CaO and / Alternatively, in the step (A) of performing an aging treatment for hydrating free MgO,
By contacting the hydration accelerator remaining after the completion of the step (A) with CO ₂ and carbonating it, one or more selected from carbonates and bicarbonates are produced, and the step (A) is performed. A step (B) of performing an aging treatment for carbonating the hydrate in a state where the product is in contact with the slag containing the hydrate of CaO and / or MgO that has passed through as a carbonation accelerator. A slag aging method characterized by having.

[13] The slag aging method according to the above [12], wherein the carbonate produced in the step (B) is at least one selected from sodium carbonate, ammonium carbonate, and potassium carbonate.
[14] In the aging method of the above [12], the slag produced in the step (B) is one or more selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, and potassium hydrogen carbonate. Aging method.
[15] The slag aging method according to any one of the above [12] to [14], wherein the aging treatment of the steps (A) and (B) is hot water aging.

[16] In the aging method of the above [15], the aging treatment of the step (A) and the aging treatment of the step (B) are sequentially performed by hot water aging on the slag placed in one treatment tank. A characteristic slag aging method.
[17] In the aging method of the above [16], when a plurality of lots of slag are sequentially aged, the solution used for hot water aging in the step (B) for one lot of slag is used for the next aging treatment. A method for aging slag, which comprises using it for hot water aging in the step (A) for slag.
[18] In any of the aging methods [12] to [17] above, in the aging treatment of the step (B), CO ₂ is blown into the slag or the warm water in which the slag is immersed. Aging method.

[19] against slag containing free CaO and / or free MgO, NaOH, KOH, being in contact one or more consisting of wettable accelerator selected from the group consisting of NH _3, slag Chumata the slag A method for aging slag, which comprises blowing CO ₂ into the immersed warm water to perform an aging treatment on the slag with the following reactions (i) and (ii).
(I) Free CaO and / or free MgO is hydrated to obtain hydrate.
(Ii) By contacting the hydration accelerator with CO ₂ and carbonating it, one or more selected from carbonates and hydrogen carbonates are produced, and the product is used as a carbonation accelerator to produce the water. Carbonate Japanese products.

[20] The slag aging method according to the above [19], wherein the carbonate produced is at least one selected from sodium carbonate, ammonium carbonate, and potassium carbonate.
[21] The slag aging method according to the above [19], wherein the bicarbonate produced is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, and potassium hydrogen carbonate.
[22] The slag aging method according to any one of the above [19] to [21], wherein the aging treatment is hot water aging.

[23] In the aging method of [22] above, when a plurality of lots of slag are sequentially aged, the solution used for hot water aging of one lot of slag is used for hot water aging of the slag of the next aging treatment. A slag aging method characterized by its use.
[24] The slag aging method according to any one of the above [1] to [23], wherein the slag is a steelmaking slag.
[25] A method for producing a civil engineering material, which comprises producing a civil engineering material by aging the slag by the aging method according to any one of the above [1] to [24].
[26] A free CaO and / or hydration accelerator for aging process slag containing free MgO, NaOH, KOH, slag, characterized in that it consists of one or more selected from _among NH 3 Hydration accelerator for aging treatment.

According to the aging method of the present invention, in the method of aging slag containing free CaO and / or free MgO, by effectively promoting hydroxylation (hydration) of free CaO and free MgO in the slag. , The aging treatment for suppressing the expansion of the slag (reducing the water immersion expansion ratio) can be performed in a short period of time. Further, according to another aging method of the present invention, the expansion of slag is suppressed (water immersion expansion ratio) by effectively promoting the hydroxylation (hydration) + carbonation of free CaO and free MgO in the slag. Aging treatment for (reduction) and suppression of elution of highly alkaline water from slag (reduction of pH of slag elution water) can be performed in a short period of time.
In addition, the aging method of the present invention can be carried out using relatively simple equipment without requiring an equipment burden such as providing a special large-scale equipment.

Explanatory drawing which shows typically the processing flow about one Embodiment of the 1st aging method of this invention. Explanatory drawing which shows typically the processing flow about one Embodiment of the 2nd aging method of this invention. Explanatory drawing which shows typically the processing flow about one Embodiment of the 3rd aging method of this invention. Explanatory drawing which shows typically the processing flow about one Embodiment of the 4th aging method of this invention.

In the aging method of the present invention, there is no particular limitation on the type of slag containing free CaO and / or free MgO to be subjected to the aging treatment, but the steelmaking slag generated in the steelmaking process of the steelmaking process includes free CaO and / or free MgO. Since it contains a relatively large amount of free MgO, it can be said that the method of the present invention is particularly useful for aging steelmaking slag. Steelmaking slag includes steelmaking slag such as decarburized slag, dephosphorization slag, desulfurization slag, desiliconization slag, and cast slag, ore reduction slag, and electric furnace slag generated in processes such as pretreatment, conversion, and casting. Although it can be mentioned, it is not limited to these, and it is also possible to target a mixture of two or more types of slag.
The particle size of the slag to be subjected to the aging treatment is not particularly limited, but generally, the particle size of the roadbed material specified by JIS A5015 is 53 mm or less. Further, since free CaO and free MgO, which cause expansion and elution of highly alkaline water, tend to be unevenly distributed in the fine particle portion of the slag, for example, slag having a particle size of 4.75 mm or less may be targeted.

First, the first aging method of the present invention will be described.
In this aging method, slag containing free CaO and / or free MgO is subjected to an aging treatment in which the free CaO and / or free MgO is hydrated in a state where a specific hydration accelerator is in contact with the slag. Is. Hereinafter, for convenience of explanation, free CaO is referred to as “CaO” and free MgO is referred to as “MgO”.
As the hydration accelerator, one or more selected from NaOH, KOH, and NH ₃ are used. This hydration accelerator reacts with CaO and MgO (CaO and / or MgO) in the slag to promote hydration of CaO and MgO, but is not consumed in the hydration reaction and is not consumed in the hydration reaction. On the other hand, it works catalytically.

Here, when the hydration accelerator is NaOH, NaOH reacts with CaO and MgO in the slag as shown in the following formulas (1a) and (1b) to promote hydration of CaO and MgO. Further, since Na ₂ O produced by this reaction reacts with H ₂ O to become NaOH as shown in the following formula (2), the overall reaction is as shown in the following formulas (3a) and (3b). That is, NaOH added as a hydration accelerator is not consumed in the hydration reaction, and promotes hydration of CaO and MgO by a catalytic action.
CaO + 2NaOH → Ca (OH) 2 + Na 2 O ... (1a)
MgO + 2NaOH → Mg (OH) 2 + Na 2 O ... (1b)
Na ₂ O + H ₂ O → 2 NaOH… (2)
CaO + H ₂ O → Ca (OH) ₂ … (3a)
MgO + H ₂ O → Mg (OH) ₂ … (3b)

When the hydration accelerator is KOH, KOH reacts with CaO and MgO in the slag as shown in the following formulas (4a) and (4b) to promote hydration of CaO and MgO. Further, since K ₂ O produced by this reaction reacts with H ₂ O to become KOH as shown in the following formula (5), the overall reaction is as shown in the following formulas (6a) and (6b). That is, KOH added as a hydration accelerator is not consumed in the hydration reaction, and promotes hydration of CaO and MgO by a catalytic action.
CaO + 2KOH → Ca (OH) 2 + K 2 O ... (4a)
MgO + 2KOH → Mg (OH) 2 + K 2 O ... (4b)
K ₂ O + H ₂ O → ₂ KOH… (5)
CaO + H ₂ O → Ca (OH) ₂ … (6a)
MgO + H ₂ O → Mg (OH) ₂ … (6b)

When the hydration accelerator is NH ₃ , NH ₃ promotes hydration of CaO and MgO in the slag as shown in the following formulas (7a) and (7b). That is, NH ₃ added as a hydration accelerator is not consumed in the hydration reaction, and promotes hydration of CaO and MgO by a catalytic action.
CaO + H ₂ O + 2NH ₃ → Ca (OH) ₂ + 2NH ₃ … (7a)
MgO + H ₂ O + 2NH ₃ → Mg (OH) ₂ + 2NH ₃ … (7b)

The aging treatment may be any of hot water aging, steam aging, atmospheric aging and the like.
In the aging treatment, the method of bringing the hydration accelerator into contact with the slag is arbitrary, but in the case of hot water aging, the hydration accelerator is added to the hot water and the slag is aged with the warm water containing the hydration accelerator. do it. In the case of steam aging or atmospheric aging, (i) a solution containing a hydration accelerator (such as an aqueous solution) is sprayed on the slag, (ii) the slag is mixed with the hydration accelerator, and (iii) hydration. A method such as temporarily immersing the slag in a solution containing an accelerator (such as an aqueous solution) may be adopted.

In this aging method, as described above, the hydration accelerator acts catalytically and is not consumed in the hydration reaction of CaO and MgO, so that it can be reused repeatedly. Therefore, in the case of hot water aging, hot water aging containing a hydration accelerator can be repeatedly reused, so that hot water aging is particularly preferable for the aging treatment. That is, when a plurality of lots of slag are sequentially aged, if the aging treatment is performed by hot water aging, the solution used for the hot water aging of the slag of one lot is used for the hot water aging of the slag of the next lot to be aged. That is, the solution can be reused between lots, and economical aging treatment can be performed.

In addition, when the aging treatment is performed by steam aging or atmospheric aging, in order to reuse the hydration accelerator, the hydration accelerator adhering to the treated slag is washed away with water or the like, and the hydration accelerator is recovered. do it. On the other hand, if the hydration accelerator is not recovered and reused, the hydration accelerator component remains attached to the slag, but this hydration accelerator component is naturally carbonated by CO ₂ in the atmosphere. So there is no problem. Further, when shipping the slag early, and the like blowing CO ₂ forced carbonation with CO ₂ hydration accelerator component may be (neutralization process) is.
There is no particular limitation on the amount of hydration accelerator added. If the amount added is small, the treatment efficiency will be low, while if the amount added is large, the load for post-treatment (neutralization treatment, etc.) of the hydration accelerator component adhering to the slag will increase. The amount of addition may be determined in consideration of these points. Further, the amount of water added may be appropriately determined according to the type of aging.

The treatment temperature (hydration reaction temperature) of the aging treatment is not particularly limited, but is preferably about 20 to 100 ° C, more preferably about 50 to 100 ° C. Therefore, from the viewpoint of this treatment temperature, hot water aging and steam aging are more preferable.
There is no particular limitation on the treatment time (aging period) of the aging treatment, but usually, the hydration of CaO and MgO in the slag proceeds sufficiently so that the slag expansion suppression (reduction of the water immersion expansion ratio) can be achieved. Set. For example, the treatment time is set so that a water immersion expansion ratio (see Examples for the measurement method) of 1.0% or less can be achieved. According to the aging method of the present invention, there is an advantage that the aging period can be significantly shortened as compared with the conventional method (simple hot water aging or steam aging).
In addition, there are no particular restrictions on the equipment for performing the aging treatment, and known equipment for performing hot water aging, steam aging, or the like can be used.

FIG. 1 schematically shows a treatment flow of one embodiment of this aging method. In this embodiment, the aging treatment is performed by hot water aging using the hydration treatment tank 1. Hereinafter, a case where the treatment target is slag containing CaO and NaOH is used as the hydration accelerator will be described as an example.
In the hydration treatment tank 1, NaOH is added as a hydration accelerator to warm water. The slag containing CaO is put into the hydration treatment tank 1 and an aging treatment (warm water aging) is performed. In this step (A), CaO is hydrated to produce Ca (OH) ₂ by the reactions of the above formulas (1a), (2) and (3a), but NaOH added as a hydration accelerator is catalytic. It works well and is not consumed in the reaction. Therefore, the hot water containing this hydration accelerator can be used as it is for hot water aging of the slag of the next lot. In this case, the addition of a new hydration accelerator may only replenish the amount that is inevitably taken out of the system.
The slag that has undergone the aging treatment (warm water aging) is taken out from the hydration treatment tank 1, dehydrated in the dehydration tank 5, and then neutralized in the neutralization treatment tank 6 for the alkali content (NaOH) of the adhering water. , Becomes a product slag. A CO ₂ containing gas is supplied to the neutralization treatment tank 6, and the alkali content (NaOH) is neutralized.

Next, the second aging method of the present invention will be described.
This aging method is a step of performing an aging treatment for hydrating the free CaO and / or the free MgO in a state where the slag containing the free CaO and / or the free MgO is in contact with a specific hydration accelerator. The hydrate is carbonated in a state where a specific carbonation accelerator is in contact with the slag containing (A) and the hydrate of CaO and / or MgO that has undergone this step (A). It has a step (B) of performing an aging process. Hereinafter, for convenience of explanation, free CaO is referred to as “CaO” and free MgO is referred to as “MgO”.

The aging treatment performed in the step (A) is basically the same as the above-mentioned first aging method of the present invention. That is, one or more selected from NaOH, KOH, and NH ₃ are used as the hydration accelerator, and the hydration accelerator is CaO in the slag as shown in the formulas (1a) to (7b) mentioned above. Promotes hydration of MgO (CaO and / or MgO). In addition, the type of aging treatment, the method of contacting the hydration accelerator with the slag in the aging treatment, the amount of the hydration accelerator added, the method of repeatedly reusing the hydration accelerator, the treatment temperature and the aging period of the aging treatment, etc. , The same as the first aging method of the present invention described above.

In the step (A), as in the first aging method of the present invention, the hydration accelerator is not consumed in the hydration reaction of CaO and MgO, so that it can be reused repeatedly. Therefore, in the case of hot water aging, hot water containing a hydration accelerator can be used repeatedly, so that the aging treatment carried out in the step (A) of the present invention is particularly preferably hot water aging. That is, when a plurality of lots of slag are sequentially aged, if the aging treatment is performed by hot water aging, the solution used for the hot water aging of the slag of one lot is used for the hot water aging of the slag of the next lot to be aged. That is, the solution can be reused between lots, and economical aging treatment can be performed.

In the step (B), one or more selected from carbonates and bicarbonates are used as the carbonation accelerator, and this carbonation accelerator hydrates CaO and MgO in the slag that has undergone the step (A). It reacts with substances, namely Ca (OH) ₂ , Mg (OH) ₂ (Ca (OH) ₂ and / or Mg (OH) ₂ ), and promotes carbonation of the hydrate.
The types of carbonate and bicarbonate are not particularly limited. For example, the carbonates include sodium carbonate (Na ₂ CO ₃ ), ammonium carbonate ((NH ₄ ) ₂ CO ₃ ), and potassium carbonate (K ₂ CO ₃ ). Examples of the hydrogen carbonate include sodium hydrogen carbonate (NaHCO ₃ ), ammonium hydrogen carbonate (NH ₄ HCO ₃ ), potassium hydrogen carbonate (KHCO ₃ ), and the like, and one or more of these should be used. Can be done.

In the step (B), when the above carbonate or bicarbonate is used as the carbonation accelerator, the reaction between Ca (OH) ₂ and Mg (OH) _{2 in} the slag and the carbonation accelerator causes the step (B). A component (for example, NaOH, KOH, etc.) corresponding to the hydration accelerator used in A) is produced. As described in the first aging method of the present invention, there is no particular problem even if this component remains attached to the slag, but during the aging treatment in step (B) and / or after the aging treatment is completed, the slag or slag is removed. The carbonation accelerator can be regenerated by blowing CO ₂ into the immersed warm water and reacting the above components (for example, NaOH, KOH, etc.) with CO ₂ . The CO ₂ may be blown into the treatment tank for the step (B), or may be carried out in a separately prepared carbonation accelerator regeneration tank. Since the carbonation accelerator can be regenerated and used in this way, the desired effect can be obtained even if the amount of the carbonation accelerator added is relatively small, and the carbonation accelerator can be reused repeatedly. There are advantages that can be done. The specific method will be described in detail later.

Here, when the carbonation accelerator is Na ₂ CO ₃ , this Na ₂ CO ₃ reacts with Ca (OH) ₂ and Mg (OH) _{2 in the} slag as shown in the following equations (8a) and (8b). Carbonation of Ca (OH) ₂ and Mg (OH) ₂ is promoted. In addition, unreacted CaO and MgO may remain even after the step (A), in which case carbonation is promoted by the reactions of the following formulas (8c) and (8d).
Ca (OH) ₂ + Na ₂ CO ₃ → CaCO ₃ + 2 NaOH… (8a)
Mg (OH) ₂ + Na ₂ CO ₃ → MgCO ₃ + 2 NaOH… (8b)
CaO + H ₂ O + Na ₂ CO ₃ → CaCO ₃ + 2 NaOH… (8c)
MgO + H ₂ O + Na ₂ CO ₃ → MgCO ₃ + 2 NaOH… (8d)

In addition, NaOH is produced by the reactions of the above formulas (8a) to (8d), and CO ₂ is added to the slag or in warm water in which the slag is immersed during and / or after the aging treatment in this step (B). By blowing in, the carbonation accelerator (Na ₂ CO ₃ ) can be regenerated as shown in the following formula (9), and the overall reaction of the aging treatment when this CO ₂ blowing is performed is as follows (10a), ( 10b) Eq.
2 NaOH + CO ₂ → Na ₂ CO ₃ + H ₂ O… (9)
Ca (OH) ₂ + CO ₂ → CaCO ₃ + H ₂ O… (10a)
Mg (OH) ₂ + CO ₂ → MgCO ₃ + H ₂ O… (10b)

When the carbonation accelerator is K ₂ CO ₃ , this K ₂ CO ₃ reacts with Ca (OH) ₂ and Mg (OH) ₂ in the slag as shown in the following equations (11a) and (11b), and Ca Carbonation of (OH) ₂ and Mg (OH) ₂ is promoted. If unreacted CaO or MgO remains even after the step (A), carbonation is promoted by the reactions of the following formulas (11c) and (11d).
Ca (OH) ₂ + K ₂ CO ₃ → CaCO ₃ + 2 KOH… (11a)
Mg (OH) ₂ + K ₂ CO ₃ → MgCO ₃ + 2 KOH… (11b)
CaO + H ₂ O + K ₂ CO ₃ → CaCO ₃ + 2KOH… (11c)
MgO + H ₂ O + K ₂ CO ₃ → MgCO ₃ + 2KOH… (11d)

Further, KOH is produced by the reactions of the above formulas (11a) to (11d), and CO ₂ is added to the slag or in warm water in which the slag is immersed during and / or after the aging treatment in this step (B). By blowing, the carbonation accelerator (K ₂ CO ₃ ) can be regenerated as shown in the following formula (12), and the overall reaction of the aging treatment when this CO ₂ blowing is performed is as follows (13a), ( 13b) Eq.
2KOH + CO ₂ → K ₂ CO ₃ + H ₂ O… (12)
Ca (OH) ₂ + CO ₂ → CaCO ₃ + H ₂ O… (13a)
Mg (OH) ₂ + CO ₂ → MgCO ₃ + H ₂ O… (13b)

When the carbonation accelerator is (NH ₄ ) ₂ CO ₃ , the (NH ₄ ) ₂ CO ₃ is Ca (OH) ₂ and Mg (OH) in the slag as shown in the following equations (14a) and (14b). Reacts with ₂ to promote carbonation of Ca (OH) ₂ and Mg (OH) ₂ . If unreacted CaO or MgO remains even after the step (A), carbonation is promoted by the reactions of the following formulas (14c) and (14d).
Ca (OH) ₂ + (NH ₄ ) ₂ CO ₃ → CaCO ₃ + 2NH ₃ + 2H ₂ O… (14a)
Mg (OH) ₂ + (NH _{4) 2} CO ₃ → MgCO ₃ + 2NH ₃ + 2H ₂ O… (14b)
CaO + H ₂ O + (NH ₄ ) ₂ CO ₃ → CaCO ₃ + 2NH ₃ + 2H ₂ O… (14c)
MgO + H ₂ O + (NH _{4) 2} CO ₃ → MgCO ₃ + 2NH ₃ + 2H ₂ O… (14d)

Further, NH ₃ is produced by the reactions of the above formulas (14a) to (14d), and CO ₂ is produced in the slag or in warm water in which the slag is immersed during and / or after the aging treatment in this step (B). As shown in the formula (15) below, the carbonation accelerator ((NH ₄ ) ₂ CO ₃ ) can be regenerated by blowing in, and the overall reaction of the aging treatment when this CO _{2 is} blown is as follows ( 16a) and (16b) are as shown.
2NH ₃ + H ₂ O + CO ₂ → (NH ₄ ) ₂ CO ₃ … (15)
Ca (OH) ₂ + CO ₂ → CaCO ₃ + H ₂ O… (16a)
Mg (OH) ₂ + CO ₂ → MgCO ₃ + H ₂ O… (16b)

When the carbonation accelerator is NaHCO ₃ , this NaHCO ₃ reacts with Ca (OH) ₂ and Mg (OH) ₂ in the slag as shown in the following formulas (17a) and (17b), and Ca (OH) ₂ , Mg (OH) ₂ carbonation is promoted. If unreacted CaO or MgO remains even after the step (A), carbonation is promoted by the reactions of the following formulas (17c) and (17d).
Ca (OH) ₂ + NaOH ₃ → CaCO ₃ + NaOH + H ₂ O… (17a)
Mg (OH) ₂ + NaOH ₃ → MgCO ₃ + NaOH + H ₂ O… (17b)
CaO + H ₂ O + NaHCO ₃ → CaCO ₃ + NaOH + H ₂ O… (17c)
MgO + H ₂ O + NaHCO ₃ → MgCO ₃ + NaOH + H ₂ O… (17d)

In addition, NaOH is produced by the reactions of the above formulas (17a) to (17d), and CO ₂ is added to the slag or in warm water in which the slag is immersed during and / or after the aging treatment in this step (B). By blowing in, the carbonation accelerator (NaHCO ₃ ) can be regenerated as shown in the following equations (18-1) and (18-2), and the overall reaction of the aging treatment when this CO ₂ blowing is performed is as follows. The following equations (19a) and (19b) are used.
2 NaOH + CO ₂ → Na ₂ CO ₃ + H ₂ O… (18-1)
Na ₂ CO ₃ + CO ₂ + H ₂ O → ₂ NaHCO ₃ … (18-2)
Ca (OH) ₂ + CO ₂ → CaCO ₃ + H ₂ O… (19a)
Mg (OH) ₂ + CO ₂ → MgCO ₃ + H ₂ O… (19b)

When the carbonation accelerator is KHCO ₃ , this KHCO ₃ reacts with Ca (OH) ₂ and Mg (OH) ₂ in the slag as shown in the following equations (20a) and (20b), and Ca (OH) ₂ , Mg (OH) ₂ carbonation is promoted. If unreacted CaO or MgO remains even after the step (A), carbonation is promoted by the reactions of the following formulas (20c) and (20d).
Ca (OH) ₂ + KHCO ₃ → CaCO ₃ + KOH + H ₂ O… (20a)
Mg (OH) ₂ + KHCO ₃ → MgCO ₃ + KOH + H ₂ O… (20b)
CaO + H ₂ O + KHCO ₃ → CaCO ₃ + KOH + H ₂ O… (20c)
MgO + H ₂ O + KHCO ₃ → MgCO ₃ + KOH + H ₂ O… (20d)

Further, KOH is produced by the reactions of the above formulas (20a) to (20d), and CO ₂ is added to the slag or in warm water in which the slag is immersed during and / or after the aging treatment in this step (B). By blowing in, the carbonation accelerator (KHCO ₃ ) can be regenerated as shown in the following formulas (21-1) and (21-2), and the overall reaction of the aging treatment when this CO ₂ blowing is performed is as follows. The following equations (22a) and (22b) are used.
2KOH + CO ₂ → K ₂ CO ₃ + H ₂ O… (21-1)
K ₂ CO ₃ + CO ₂ + H ₂ O → ₂ KHCO ₃ … (21-2)
Ca (OH) ₂ + CO ₂ → CaCO ₃ + H ₂ O… (22a)
Mg (OH) ₂ + CO ₂ → MgCO ₃ + H ₂ O… (22b)

When the carbonation accelerator is NH ₄ HCO ₃ , this NH ₄ HCO ₃ reacts with Ca (OH) ₂ and Mg (OH) ₂ in the slag as shown in the following equations (23a) and (23b), and Ca Carbonation of (OH) ₂ and Mg (OH) ₂ is promoted. If unreacted CaO or MgO remains even after the step (A), carbonation is promoted by the following reactions (23c) and (23d).
Ca (OH) ₂ + NH ₄ HCO ₃ → CaCO ₃ + NH ₃ + 2H ₂ O… (23a)
Mg (OH) ₂ + NH ₄ HCO ₃ → MgCO ₃ + NH ₃ + 2H ₂ O… (23b)
CaO + H ₂ O + NH ₄ HCO ₃ → CaCO ₃ + NH ₃ + 2H ₂ O… (23c)
MgO + H ₂ O + NH ₄ HCO ₃ → MgCO ₃ + NH ₃ + 2H ₂ O… (23d)

Further, NH ₃ is produced by the reactions of the above formulas (23a) to (23d), and CO ₂ is produced in the slag or in warm water in which the slag is immersed during and / or after the aging treatment in this step (B). As shown in the following equations (24-1) and (24-2), the carbonation accelerator (NH ₄ HCO ₃ ) can be regenerated by blowing in, and the aging process when this CO _{2 is} blown is summarized. The reaction is as shown in the following formulas (25a) and (25b).
2NH ₃ + H ₂ O + CO ₂ → (NH ₄ ) ₂ CO ₃ … (24-1)
(NH ₄ ) ₂ CO ₃ + H ₂ O + CO ₂ → 2 NH ₄ HCO ₃ … (24-2)
Ca (OH) ₂ + CO ₂ → CaCO ₃ + H ₂ O… (25a)
Mg (OH) ₂ + CO ₂ → MgCO ₃ + H ₂ O… (25b)

The aging treatment in the step (B) may be any of hot water aging, steam aging, atmospheric aging and the like.
In the aging treatment of the step (B), the method of bringing the carbonation accelerator into contact with the slag is arbitrary, but in the case of hot water aging, the carbonation accelerator is added to the hot water, and the hot water containing the carbonation accelerator is added. The slag may be aged. In the case of steam aging or atmospheric aging, (i) a solution containing a carbonation accelerator (such as an aqueous solution) is sprayed on the slag, (ii) a carbonation accelerator is mixed with the slag, and (iii) carbonation. A method such as temporarily immersing the slag in a solution containing an accelerator (such as an aqueous solution) may be adopted.

As described above, it is used in the step (A) by the reaction of Ca (OH) ₂ and Mg (OH) ₂ in the slag in the step (B) with a carbonation accelerator (specific carbonate, bicarbonate). A component corresponding to the hydration accelerator (for example, NaOH, KOH, etc.) was produced, but during the aging treatment (at least a part of the aging period) in step (B) and / and after the aging treatment was completed, the slag was formed. The carbonation accelerator can be regenerated by blowing CO ₂ into the immersed warm water and reacting the above components (for example, NaOH, KOH, etc.) with CO ₂ . By injecting CO ₂ into slag or warm water in this way, the treatment can be performed while regenerating the carbonation accelerator, so that the amount of the carbonation accelerator added can be relatively small. In addition, the carbonation accelerator can be reused repeatedly.

Therefore, when the aging treatment of the step (B) is performed by hot water aging, the carbonation accelerator can be regenerated only by blowing CO ₂ into warm water during and / or after the aging treatment is completed. It is particularly advantageous because hot water containing a carbonation accelerator can be reused repeatedly. From this point of view, hot water aging is particularly preferable for the aging treatment. That is, when a plurality of lots of slag are sequentially aged, if the aging treatment is performed by hot water aging, the solution used for the hot water aging of the slag of one lot (during the aging treatment and / and after the aging treatment is completed, CO ₂ is blown into the solution). The solution) can be used for hot water aging of the slag of the lot to be aged next, that is, the solution can be reused between lots, and economical aging can be performed.

On the other hand, in the case where the aging treatment of the step (B) is performed by steam aging or atmospheric aging, in order to regenerate the carbon dioxide accelerator and reuse it, the aging treatment of the step (B) is being performed or / and the aging treatment is completed. Later, the carbonation accelerator may be regenerated by blowing CO ₂ into the slag, and then the carbonation accelerator adhering to the treated slag may be washed away with water or the like to recover the carbonation accelerator.
In order to blow CO ₂ (gas) into slag or warm water in the step (B), CO ₂ containing gas (for example, metallurgical furnace exhaust gas, combustion exhaust gas, lime firing furnace exhaust gas, etc.) may be used. Although CO ₂ CO ₂ concentration of the gas containing is not particularly limited, the processing efficiency, CO ₂ concentration is preferably used 10 vol% or more CO ₂ containing gas.
In addition, in order to blow CO ₂ (including the case of CO ₂ containing gas) into the slag, for example, the slag is stacked on a settlement floor on which a steam pipe equipped with a blowing nozzle is laid, and the steam pipe is blown. A method such as blowing CO ₂ from the nozzle into the slag layer can be adopted.

There is no particular limitation on the amount of carbonation accelerator added, but since the carbonation accelerator reacts with soluble CaO and soluble MgO other than free CaO and free MgO contained in the slag, treatment is performed while taking this point into consideration. It may be decided appropriately from the aspect of efficiency.
The content of soluble CaO and soluble MgO (sustainable CaO, MgO) in the slag can be determined by, for example, the following measuring method.
5 g of distilled water is added to 2 g of slag crushed to a particle size of 0.075 mm or less, and the slag is cured in an autoclave at 180 ° C. for 24 hours. All CaO and MgO that can be hydrated by this treatment are converted into Ca (OH) ₂ and Mg (OH) ₂ . The following thermogravimetric analysis is performed on the hydrated slag. The conditions of this thermogravimetric analysis are that the temperature range is normal temperature to 600 ° C., the heating rate is 10 ° C./min, and the flow rate is 200 mL / min in an argon atmosphere. Considering that the mass loss at 300-400 ° C is due to the dehydration reaction of Mg (OH) ₂ and the mass loss at 400-500 ° C is due to the dehydration reaction of Ca (OH) ₂ , the amount of hydrateable CaO (as shown below) The amount of soluble CaO) and the amount of hydrateable MgO (amount of soluble MgO) are calculated.
Hydogenic MgO (mass%) = W _300-400 * 40.3 / 18.0
Hydogenic CaO (mass%) = W _400-500 * 56.1 / 18.0
Here, W _300-400 : Amount of dehydration at 300-400 ° C (mass%)
W _400-500 : Dehydration amount at 400-500 ° C (mass%)

The treatment temperature (carbonation reaction temperature) of the aging treatment in the step (B) is not particularly limited, but is preferably about 20 to 80 ° C, more preferably about 40 to 60 ° C. Therefore, from the viewpoint of this treatment temperature, hot water aging is preferable for the aging treatment.
There is no particular limitation on the treatment time of the aging treatment in the step (B), but usually, the carbonization of Ca (OH) ₂ and Mg (OH) _{2 in} the slag proceeds sufficiently to suppress the expansion of the slag (water immersion expansion). It is set so as to achieve (reduction of ratio) and suppression of elution of highly alkaline water from slag (reduction of pH of slag elution water). For example, the treatment time is set so that a water immersion expansion ratio (see Examples for the measurement method) of 1.0% or less and a pH measured in the tank leaching test (see Examples for the measurement method) of 10.0 or less can be achieved. To. According to the aging method of the present invention, there is an advantage that the aging period can be significantly shortened as compared with the conventional method (simple hot water aging or steam aging).

There are no special restrictions on the equipment that carries out the aging treatment of steps (A) and (B), and known equipment that performs hot water aging, steam aging, etc. can be used, but as mentioned earlier, step (i) ( In A), since the hydration accelerator is not consumed in the hydration reaction of CaO and MgO, in the case of hot water aging, the hot water containing the hydration accelerator can be repeatedly reused, step (ii) (ii). In B), in the case of hot water aging, the carbonation accelerator can be regenerated simply by blowing CO ₂ into warm water during and / or after the aging treatment is completed, and the hot water containing this carbonization accelerator can be regenerated. From the viewpoint that it can be reused repeatedly, it is particularly preferable that the aging treatment of the step (A) and the aging treatment of the step (B) are performed by hot water aging using a dedicated treatment tank. As a result, when aging a plurality of lots of slag in sequence, in each of the hot water aging steps (A) and (B), the solution used for the hot water aging of one lot of slag is then subjected to the aging treatment. It can be used for hot water aging of slag, that is, the solution can be reused between lots, and economical aging treatment can be performed.

FIG. 2 schematically shows a processing flow of one embodiment of this aging method. In this embodiment, the aging process of the step (A) and the aging process of the step (B) are dedicated to each of them. It is performed by hot water aging using a tank. Hereinafter, a case where the treatment target is slag containing CaO, NaOH is used as the hydration accelerator in the step (A), and Na ₂ CO ₃ is used as the carbonation accelerator in the step (B) will be described as an example.
In the hydration treatment tank 1, NaOH is added as a hydration accelerator to warm water. The slag containing CaO is put into the hydration treatment layer 1, and the aging treatment (warm water aging) of the step (A) is performed. In this step (A), CaO is hydrated to produce Ca (OH) ₂ by the reactions of the above formulas (1a), (2) and (3a), but NaOH added as a hydration accelerator is catalytic. It works well and is not consumed in the reaction. Therefore, the hot water containing this hydration accelerator can be used as it is for hot water aging of the slag of the next lot. In this case, the addition of a new hydration accelerator may only replenish the amount that is inevitably taken out of the system.

The slag containing Ca (OH) ₂ that has completed the step (A) is transferred to the carbonation treatment tank 2, where the aging treatment (warm water aging) of the step (B) is performed. In the carbon dioxide treatment vessel 2, it is added _Na 2 CO ₃ as a carbonation promoter in hot water, Ca _{(OH) 2} in the slag is CaCO ₃ caused by carbonation. Further, in this step (B), in order to regenerate the carbonation accelerator (Na ₂ CO ₃ ) consumed for the carbonation of Ca (OH) ₂ , warm water is used during and / or after the aging treatment is completed. Blow CO ₂ into it.

In this step (B), the reactions of the above-mentioned formulas (8a), (9) and (10a) (in some cases, further formula (8c)) occur. The action of the carbonation accelerator promotes the carbonation of Ca (OH) _{2 in} the slag, and the NaOH produced by the carbonation reaction reacts with the CO ₂ blown into the warm water to promote the carbonation. (Na ₂ CO ₃ ) is regenerated. Therefore, the amount of the carbonation accelerator added may be relatively small, and the hot water in which the carbonation accelerator (Na ₂ CO ₃ ) is regenerated can be used as it is for the hot water aging of the slag of the next lot. .. In this case, the addition of a new carbonation accelerator may only replenish the amount that is inevitably taken out of the system.

The CO ₂ for regenerating the carbonation accelerator (Na ₂ CO ₃ ) may be blown into the carbonation treatment tank 2 by using a gas blowing means (in this case, the gas blowing means 7). Is shown by a virtual line in the figure), in this embodiment, CO ₂ is blown into the dedicated carbonation accelerator regeneration tank 3. That is, the liquid (warm water) in the carbonation treatment tank 2 is extracted and supplied to the carbonation accelerator regeneration tank 3 (path 16a), and the CO ₂ containing gas is supplied to the carbonation accelerator regeneration tank 3 to carbonate the carbon dioxide. Regenerate the carbon dioxide accelerator. Then, the liquid (carbonation accelerator solution) that has been regenerated with this carbonation accelerator is stored in the storage tank 4, and if necessary, a new carbonation accelerator is added to adjust the concentration, and then the carbonation treatment tank. Supply to 2 (path 16b).
In addition, unlike the embodiment of FIG. 2, when CO ₂ is not blown into warm water, the carbonation accelerator (Na ₂ CO ₃ ) is not regenerated during the treatment, so that the amount of the carbonation accelerator added is appropriate. Is required.
The slag that has completed the step (B) is taken out from the carbonation treatment tank 2, dehydrated in the dehydration tank 5, and then neutralized in the neutralization treatment tank 6 for the alkali content (NaOH) of the adhering water. It becomes a slag. The CO _2- containing gas from the carbonation accelerator regeneration tank 3 is supplied to the neutralization treatment tank 6, and the alkali content (NaOH) is neutralized.

Next, the third aging method of the present invention will be described.
This aging method is a step of performing an aging treatment for hydrating the free CaO and / or the free MgO in a state where the slag containing the free CaO and / or the free MgO is in contact with a specific hydration accelerator. By contacting (A) and the hydration accelerator remaining after the completion of this step (A) with CO ₂ and carbonizing the mixture, one or more selected from carbonates and hydrogen carbonates are produced. The slag containing the hydrate of CaO and / or MgO that has undergone the step (A) is subjected to an aging treatment for carbonating the hydrate in a state where the product is brought into contact with the slag as a carbonation accelerator. It has a step (B). Hereinafter, for convenience of explanation, free CaO is referred to as “CaO” and free MgO is referred to as “MgO”.

The aging treatment performed in the step (A) is basically the same as the first and second aging methods of the present invention described above. That is, one or more selected from NaOH, KOH, and NH ₃ are used as the hydration accelerator, and the hydration accelerator is CaO in the slag as shown in the formulas (1a) to (7b) mentioned above. Promotes hydration of MgO (CaO and / or MgO). Further, the types of the aging treatment, the method of bringing the hydration accelerator into contact with the slag in the aging treatment, the amount of the hydration accelerator added, the treatment temperature of the aging treatment, the aging period and the like are also described in the first and second aspects of the present invention described above. It is the same as the aging method of.

In the step (A), as in the second aging method of the present invention, the hydration accelerator remains without being consumed in the hydration reaction of CaO and MgO, but in the subsequent step (B), this hydration accelerator remains. A carbonation accelerator is produced from the remaining hydration accelerator, and this carbonation accelerator is used as Ca (OH) ₂ , Mg (OH) ₂ (Ca (OH) ₂ and Ca (OH) ₂ ) in the slag that has undergone the step (A). / Or As a result of reacting with Mg (OH) ₂ ), a hydration accelerator is generated again, and this can be reused repeatedly. Therefore, in the case of hot water aging, hot water containing the hydration accelerator can be reused repeatedly, so that the aging treatment carried out in the steps (A) and (B) is particularly preferably hot water aging. That is, when the slags of a plurality of lots are sequentially aged, if the aging treatments of the steps (A) and (B) are sequentially performed by hot water aging, the solution used for the hot water aging of the step (B) for one lot of slag. Is used for hot water aging in the step (A) for the slag of the lot to be aged next, that is, the solution can be reused between lots, and the economical aging treatment can be performed.

As described above, in the step (A), the hydration accelerator is not consumed in the hydration reaction of CaO and MgO, and remains as it is even after the completion of the step. In the step (B), the hydration accelerator (for example, NaOH, KOH, etc.) remaining after the completion of the step (A) is contacted (reacted) with CO ₂ to be carbonated, so that the carbonate and the hydrogen carbonate are contained. Generate one or more selected from. Then, as a carbonation accelerator, this product is a hydrate of CaO and MgO in the slag that has undergone the step (A), that is, Ca (OH) ₂ , Mg (OH) ₂ (Ca (OH) ₂ and / or It reacts with Mg (OH) ₂ ) and promotes carbonation of the hydrate.

Since the hydration accelerator used in the step (A) is one or more of NaOH, KOH, and NH ₃ , a carbonate or bicarbonate (carbonate) produced by reacting (carbonation reaction) this with CO ₂ ( (Carbonation accelerator) is sodium carbonate (Na ₂ CO ₃ ), sodium hydrogen carbonate (NaHCO ₃ ), potassium carbonate (K ₂ CO ₃ ), potassium hydrogen carbonate (KHCO ₃ ), ammonium carbonate ((NH ₄ ) ₂ CO). ₃ ), one or more of ammonium hydrogen carbonate (NH ₄ HCO ₃ ). The carbonation of the hydration accelerator proceeds in the order of carbonate and hydrogen carbonate.
In order to bring the hydration accelerator remaining after the completion of the step (A) into contact with CO ₂ and carbonate it, CO ₂ (gas) is usually blown into slag or warm water in which the slag is immersed. The CO ₂ may be blown into the aging treatment tank, or may be carried out in a separately prepared carbonation accelerator generation tank.
In order to blow CO ₂ (gas) into slag or warm water, CO ₂ containing gas (for example, metallurgical furnace exhaust gas, combustion exhaust gas, lime firing furnace exhaust gas, etc.) may be used. Although CO ₂ CO ₂ concentration of the gas containing is not particularly limited, the processing efficiency, CO ₂ concentration is preferably used 10 vol% or more CO ₂ containing gas.
The method of blowing CO ₂ into the slag or the warm water in which the slag is immersed is the same as the second aging method of the present invention described above.

Here, when the hydration accelerator used in the step (A) is NaOH, the following (26) and (27) are made by blowing CO ₂ into the slag or in the warm water in which the slag is immersed in the step (B). It is _Na 2 CO ₃ and / or NaHCO ₃ as a carbonation promoter as shown in equation produce. As shown in the following equations (26) and (27), the carbonation of NaOH proceeds in the order of carbonate and bicarbonate, and the degree of progress of carbonation is determined by the amount of CO ₂ supplied and the time. Even if carbonate is produced, hydrogen carbonate may not be produced.
2 NaOH + CO ₂ → Na ₂ CO ₃ + H ₂ O… (26)
Na ₂ CO ₃ + CO ₂ + H ₂ O → ₂ NaHCO ₃ … (27)

The Na ₂ CO ₃ and / or NaHCO ₃ thus produced are the Ca (OH) ₂ and Mg (OH) _{2 in the} slag as shown in the following equations (28a), (28b), (29a) and (29b). The reaction promotes carbonation of Ca (OH) ₂ and Mg (OH) ₂ . In addition, unreacted CaO and MgO may remain even after the step (A), in which case carbonation is carried out by the following reactions (28c), (28d), (29c) and (29d). Be promoted.
Ca (OH) ₂ + Na ₂ CO ₃ → CaCO ₃ + 2 NaOH… (28a)
Mg (OH) ₂ + Na ₂ CO ₃ → MgCO ₃ + 2 NaOH… (28b)
CaO + H ₂ O + Na ₂ CO ₃ → CaCO ₃ + 2 NaOH… (28c)
MgO + H ₂ O + Na ₂ CO ₃ → MgCO ₃ + 2 NaOH… (28d)
Ca (OH) ₂ + NaOH ₃ → CaCO ₃ + NaOH + H ₂ O… (29a)
Mg (OH) ₂ + NaOH ₃ → MgCO ₃ + NaOH + H ₂ O… (29b)
CaO + H ₂ O + NaHCO ₃ → CaCO ₃ + NaOH + H ₂ O… (29c)
MgO + H ₂ O + NaHCO ₃ → MgCO ₃ + NaOH + H ₂ O… (29d)
Therefore, the overall reaction of the aging treatment in the step (B) is as shown in the following equations (30a) and (30b).
Ca (OH) ₂ + CO ₂ → CaCO ₃ + H ₂ O… (30a)
Mg (OH) ₂ + CO ₂ → MgCO ₃ + H ₂ O… (30b)

When the hydration accelerator used in the step (A) is KOH, CO ₂ is blown into the slag or the warm water in which the slag is immersed in the step (B) to obtain the following equations (31) and (32). becomes carbonation promoter _K 2 CO ₃ and / or KHCO ₃ as shown to generate. As shown in equations (31) and (32) below, carbonation of KOH proceeds in the order of carbonate and bicarbonate, and the degree of progress of carbonation is determined by the amount of CO ₂ supplied and time. Even if carbonate is produced, hydrogen carbonate may not be produced.
2KOH + CO ₂ → K ₂ CO ₃ + H ₂ O… (31)
K ₂ CO ₃ + CO ₂ + H ₂ O → ₂ KHCO ₃ … (32)

_K 2 CO ₃ and / or KHCO ₃ generated in this manner is the following (33a), (33b), (34a), and ₂ (34b) of as slag of formula _{Ca (OH) 2, Mg (} OH) The reaction promotes carbonation of Ca (OH) ₂ and Mg (OH) ₂ . If unreacted CaO or MgO remains even after the step (A), carbonation is promoted by the following reactions (33c), (33d), (34c), and (34d).
Ca (OH) ₂ + K ₂ CO ₃ → CaCO ₃ + 2 KOH… (33a)
Mg (OH) ₂ + K ₂ CO ₃ → MgCO ₃ + 2 KOH… (33b)
CaO + H ₂ O + K ₂ CO ₃ → CaCO ₃ + 2KOH… (33c)
MgO + H ₂ O + K ₂ CO ₃ → MgCO ₃ + 2KOH… (33d)
Ca (OH) ₂ + KHCO ₃ → CaCO ₃ + KOH + H ₂ O… (34a)
Mg (OH) ₂ + KHCO ₃ → MgCO ₃ + KOH + H ₂ O… (34b)
CaO + H ₂ O + KHCO ₃ → CaCO ₃ + KOH + H ₂ O… (34c)
MgO + H ₂ O + KHCO ₃ → MgCO ₃ + KOH + H ₂ O… (34d)
Therefore, the overall reaction of the aging treatment in the step (B) is as shown in the following equations (35a) and (35b).
Ca (OH) ₂ + CO ₂ → CaCO ₃ + H ₂ O… (35a)
Mg (OH) ₂ + CO ₂ → MgCO ₃ + H ₂ O… (35b)

When the hydration accelerator used in the step (A) is NH ₃ , CO ₂ is blown into the slag or the warm water in which the slag is immersed in the step (B) to obtain the following (36) and (37). As shown in the formula, (NH ₄ ) ₂ CO ₃ and / or NH ₄ HCO _{3 serving as a} carbonation accelerator is produced. As shown in equations (36) and (37) below, the carbonation of NH ₃ proceeds in the order of carbonate and bicarbonate, and the degree of progress of carbonation is determined by the amount of CO ₂ supplied and the time. , Even if carbonate is produced, hydrogen carbonate may not be produced.
2NH ₃ + H ₂ O + CO ₂ → (NH ₄ ) ₂ CO ₃ … (36)
(NH ₄ ) ₂ CO ₃ + H ₂ O + CO ₂ → 2 NH ₄ HCO ₃ … (37)

The (NH ₄ ) ₂ CO ₃ and / or NH ₄ HCO ₃ thus generated are Ca (OH) ₂ and Mg in the slag as shown in the following equations (38a), (38b), (39a) and (39b). _{(OH) 2} and _reacted, Ca (OH) 2, Mg _{(OH) 2} carbonation is accelerated. If unreacted CaO or MgO remains even after the step (A), carbonation is promoted by the following reactions (38c), (38d), (39c), and (39d).
Ca (OH) ₂ + (NH ₄ ) ₂ CO ₃ → CaCO ₃ + 2NH ₃ + 2H ₂ O… (38a)
Mg (OH) ₂ + (NH _{4) 2} CO ₃ → MgCO ₃ + 2NH ₃ + 2H ₂ O… (38b)
CaO + H ₂ O + (NH ₄ ) ₂ CO ₃ → CaCO ₃ + 2NH ₃ + 2H ₂ O… (38c)
MgO + H ₂ O + (NH _{4) 2} CO ₃ → MgCO ₃ + 2NH ₃ + 2H ₂ O… (38d)
Ca (OH) ₂ + NH ₄ HCO ₃ → CaCO ₃ + NH ₃ + 2H ₂ O… (39a)
Mg (OH) ₂ + NH ₄ HCO ₃ → MgCO ₃ + NH ₃ + 2H ₂ O… (39b)
CaO + H ₂ O + NH ₄ HCO ₃ → CaCO ₃ + NH ₃ + 2H ₂ O… (39c)
MgO + H ₂ O + NH ₄ HCO ₃ → MgCO ₃ + NH ₃ + 2H ₂ O… (39d)
Therefore, the overall reaction of the aging treatment in the step (B) is as shown in the following equations (40a) and (40b).
Ca (OH) ₂ + CO ₂ → CaCO ₃ + H ₂ O… (40a)
Mg (OH) ₂ + CO ₂ → MgCO ₃ + H ₂ O… (40b)

The aging treatment in the steps (A) and (B) may be any of hot water aging, steam aging, atmospheric aging and the like, but hot water aging is particularly preferable as described above. That is, in the step (B), the produced carbonation accelerator reacts with Ca (OH) ₂ and Mg (OH) ₂ in the slag to generate a hydration accelerator again, which can be reused repeatedly. This is possible, and in the case of hot water aging, the hot water containing the hydration accelerator can be reused repeatedly.
In the aging treatments of the steps (A) and (B), the method of contacting the hydration accelerator (and the carbonation accelerator produced from the hydration accelerator) with the slag is arbitrary, but in the case of hot water aging, , The slag may be aged with warm water containing a hydration accelerator (and a carbonation accelerator produced from the hydration accelerator). In the case of steam aging or atmospheric aging, in performing step (A), (i) a solution containing a hydration accelerator (such as an aqueous solution) is sprayed on the slag, and (ii) a hydration accelerator is applied to the slag. A method such as mixing, (iii) temporarily immersing the slag in a solution containing a hydration accelerator (such as an aqueous solution), or the like may be adopted.

Further, in the case where the aging treatment is performed by steam aging or atmospheric aging, in order to reuse the hydration accelerator, the hydration accelerator adhering to the slag after the aging treatment in the step (B) is washed away with water or the like, and water is used. The sum accelerator may be recovered. On the other hand, if the hydration accelerator is not recovered and reused, the hydration accelerator component remains attached to the slag, but this hydration accelerator component is naturally carbonated by CO ₂ in the atmosphere. So there is no problem. Further, when shipping the slag early, and the like blowing CO ₂ forced carbonation with CO ₂ hydration accelerator component may be (neutralization process) is.

The treatment temperature (carbonation reaction temperature) of the aging treatment in the step (B) is not particularly limited, but is preferably about 20 to 80 ° C, more preferably about 40 to 60 ° C. Therefore, hot water aging is preferable from the viewpoint of this treatment temperature.
There is no particular limitation on the treatment time of the aging treatment in the step (B), but usually, the carbonization of Ca (OH) ₂ and Mg (OH) _{2 in} the slag proceeds sufficiently to suppress the expansion of the slag (water immersion expansion). It is set so as to achieve (reduction of ratio) and suppression of elution of highly alkaline water from slag (reduction of pH of slag elution water). For example, the treatment time is set so that a water immersion expansion ratio (see Examples for the measurement method) of 1.0% or less and a pH measured in the tank leaching test (see Examples for the measurement method) of 10.0 or less can be achieved. To. According to the aging method of the present invention, there is an advantage that the aging period can be significantly shortened as compared with the conventional method (simple hot water aging or steam aging).
There are no particular restrictions on the equipment that carries out the aging treatment of steps (A) and (B), and known equipment that performs hot water aging, steam aging, etc. can be used, but as mentioned earlier, steps (A), Since it is preferable to perform (B) by hot water aging, the aging treatment of step (A) and the aging treatment of step (B) are sequentially performed by hot water aging on the slag placed in one treatment tank. It is preferable to do so.

FIG. 3 schematically shows the processing flow of one embodiment of this aging method. In this embodiment, the aging process of the step (A) and the aging of the step (B) are performed in one processing tank 8. The treatment is sequentially performed by hot water aging. Hereinafter, a case where the treatment target is slag containing CaO and NaOH is used as the hydration accelerator in the step (A) will be described as an example.
In the treatment tank 8, NaOH is added as a hydration accelerator to warm water. The slag containing CaO is put into the treatment layer 8, and the aging treatment (warm water aging) of the step (A) is performed. In this step (A), CaO is hydrated to produce Ca (OH) ₂ by the reactions of the above formulas (1a), (2) and (3a), but NaOH added as a hydration accelerator is catalytic. It works well and is not consumed in the reaction.

Next, in step (B), CO ₂ is blown into warm water to carbonate NaOH to produce Na ₂ CO ₃ . Then, aging treatment (warm water aging) is performed using this Na ₂ CO ₃ as a carbonation accelerator, and Ca (OH) ₂ in the slag is carbonated to generate CaCO ₃ . In this step (B), the reactions of the above-mentioned formulas (26), (28a) and (30a) (in some cases, further formula (28c)) occur. In the hot water aging in this step (B), NaOH as a hydration accelerator is regenerated, so that the hot water containing this hydration accelerator can be used as it is for the hot water aging of the slag of the next lot. In this case, the addition of a new hydration accelerator may only replenish the amount that is inevitably taken out of the system.

Blowing of CO ₂ for NaOH was allowed to carbonated to produce Na ₂ CO ₃ is may be performed using a gas blowing means in the processing vessel 8 (FIG gas blowing means 11 in this case (Indicated by a virtual line inside), in this embodiment, CO ₂ is blown into the dedicated carbonation accelerator generation tank 9. That is, the liquid (warm water) in the treatment tank 8 is extracted and supplied to the carbonation accelerator generation tank 9 (path 17a), and the carbonation promotion is promoted by supplying the CO ₂ containing gas to the carbonation accelerator generation tank 9. Generate an agent. Then, the liquid (carbonation accelerator solution) subjected to the formation treatment of this carbonation accelerator is stored in the storage tank 10, and if necessary, a separately prepared carbonation accelerator is added to adjust the concentration, and then the treatment is performed. It is supplied to the tank 8 (path 17b).
The slag that has completed the step (B) is taken out from the treatment tank 8, dehydrated in the dehydration tank 5, and then neutralized in the neutralization treatment tank 6 for the alkali content (NaOH) of the adhering water to form the product slag. Become. The CO _2- containing gas from the carbonation accelerator generation tank 9 is supplied to the neutralization treatment tank 6, and the alkali content (NaOH) is neutralized.

Next, the fourth aging method of the present invention will be described.
This aging method is such that the reaction of the step (A) and the reaction of the step (B) in the third aging method of the present invention described above occur in parallel at the same time. That is, CO ₂ is blown into the slag containing free CaO and / or free MgO in a state where a specific hydration accelerator is in contact with the slag or in warm water in which the slag is immersed. The aging treatment is performed with the following reactions (i) and (ii).
(I) Free CaO and / or free MgO is hydrated to obtain hydrate.
(Ii) By contacting the hydration accelerator with CO ₂ and carbonating it, one or more selected from carbonates and hydrogen carbonates are produced, and the product is used as a carbonation accelerator to produce the water. Carbonate Japanese products.
Hereinafter, for convenience of explanation, free CaO is referred to as “CaO” and free MgO is referred to as “MgO”.

In this aging method, the point of promoting the hydration of CaO and MgO (CaO and / or MgO) by the reaction of the above (i) is the step (A) of the third aging method of the present invention described above (the present invention). The steps (A) of the first aging method and the second aging method are basically the same. That is, one or more selected from NaOH, KOH, and NH ₃ are used as the hydration accelerator, and the hydration accelerator is CaO in the slag as shown in the above formulas (1a) to (7b). Promotes hydration of MgO. Further, the type of aging treatment, the method of bringing the hydration accelerator into contact with the slag in the aging treatment, the amount of the hydration accelerator added, the treatment temperature of the aging treatment, the aging period and the like are also described in the third aging method of the present invention described above. (And the first and second aging methods).

Further, by the reaction of (ii) above, the hydrates of CaO and MgO, that is, Ca (OH) ₂ , Mg (OH) ₂ (Ca (OH) ₂ and / or Mg (OH) ₂ ) are carbonated. The point of promotion is basically the same as the step (B) of the third aging method of the present invention described above. That is, by contacting (reacting) a hydration accelerator (for example, NaOH, KOH, etc.) with CO ₂ to carbonate, one or more selected from carbonates and bicarbonates are produced, and this product is produced. As a carbonation accelerator, reacts with Ca (OH) ₂ and Mg (OH) ₂ produced in the reaction (i) above to promote carbonation of the hydrate.

In the step (A) of the third aging method of the present invention described above, the hydration accelerator remains without being consumed in the hydration reaction of CaO and MgO, and in the subsequent step (B), it remains. with carbonation promoter is generated from the remaining hydrated promoter, the carbonation promoter reacts with _{Ca (OH) 2, Mg (} OH) 2 ( i.e. _{Ca (OH) 2, Mg (} OH) As a result of carbonizing ₂ ), a hydration accelerator is produced again. On the other hand, in the present aging method (the fourth aging method of the present invention), the above reactions proceed simultaneously and in parallel in one processing step. Therefore, in the case of hot water aging, hot water containing a hydration accelerator can be repeatedly reused, so that hot water aging is particularly preferable for the aging treatment. That is, when sequentially aging a plurality of lots of slag, the solution used for hot water aging for the slag of one lot is used for hot water aging for the slag of the next lot to be aged, that is, the solution of the solution between lots. It can be reused and economical aging processing can be performed.

Since the hydration accelerator used in this aging method is one or more of NaOH, KOH, and NH ₃ , a carbonate or hydrogen carbonate (carbonate) produced by reacting this with CO ₂ (carbonation reaction) (Chemical accelerator) is sodium carbonate (Na ₂ CO ₃ ), sodium hydrogen carbonate (NaHCO ₃ ), potassium carbonate (K ₂ CO ₃ ), potassium hydrogen carbonate (KHCO ₃ ), ammonium carbonate ((NH ₄ ) ₂ CO ₃ ). ), Ammonium hydrogen carbonate (NH ₄ HCO ₃ ) or more. The carbonation of the hydration accelerator proceeds in the order of carbonate and bicarbonate, and the degree of progress of carbonation is determined by the amount of CO ₂ supplied and the time. Therefore, even if carbonate is produced, hydrogen carbonate May not be generated.

In this aging method, CO ₂ may be blown into the slag or the warm water in which the slag is immersed, either in the aging treatment tank or in a separately prepared carbonation accelerator generation tank.
In order to blow CO ₂ (gas) into slag or warm water in which slag is immersed, CO ₂ containing gas (for example, metallurgical furnace exhaust gas, combustion exhaust gas, lime firing furnace exhaust gas, etc.) may be used. Although CO ₂ CO ₂ concentration of the gas containing is not particularly limited, the processing efficiency, CO ₂ concentration is preferably used 10 vol% or more CO ₂ containing gas.
The method of blowing CO ₂ into the slag or the warm water in which the slag is immersed is the same as the second aging method of the present invention described above.

Hereinafter, the reactions (i) and (ii) in this aging method will be described based on the chemical reaction formulas mentioned above. When the hydration accelerator used in this aging method is NaOH, (1a), As shown in the equations (1b), (2), (3a) and (3b), the hydration reaction of CaO and MgO in the slag occurs, and the hydration of CaO and MgO is promoted. Furthermore, by slag Chumata is blowing CO ₂ in warm water soaking slag, (26), (27) a carbonation promoter reacts with NaOH as shown in formula _Na 2 CO ₃ and / or NaHCO ₃ (Note that, as shown in equations (26) and (27), the carbonation of NaOH proceeds in the order of carbonate and bicarbonate, and the degree of progress of carbonation depends on the amount of CO ₂ supplied and the time. Because it is determined, even if carbonate is produced, hydrogen carbonate may not be produced.) _Na 2 CO ₃ and / or NaHCO ₃ is generated in this manner, (28a), (28b) , (29a), and ₂ (29 b) of as slag of formula _{Ca (OH) 2, Mg (} OH) The reaction promotes carbonation of Ca (OH) ₂ and Mg (OH) ₂ . In addition, the produced Na ₂ CO ₃ and / or Na HCO ₃ also reacts with unreacted CaO and MgO that have not been hydrated as shown in the formulas (28c), (28d), (29c) and (29d), and they Carbonation is promoted. Therefore, the overall reaction in (ii) above is as shown in equations (30a) and (30b).

When the hydration accelerator is KOH, the hydration reaction of CaO and MgO in the slag occurs as shown in the formulas (4a), (4b), (5), (6a) and (6b), and CaO and MgO Hydration is promoted. Furthermore, by slag Chumata is blowing CO ₂ in warm water soaking the slag, (31), (32) a carbonation promoter reacts with KOH as shown in formula _K 2 CO ₃ and / or KHCO ₃ (Note that, as shown in equations (31) and (32), carbonation of KOH proceeds in the order of carbonate and bicarbonate, and the degree of progress of carbonation depends on the amount of CO ₂ supplied and the time. Because it is determined, even if carbonate is produced, hydrogen carbonate may not be produced.) _K 2 CO ₃ and / or KHCO ₃ generated in this manner, (33a), (33b) , (34a), and ₂ (34b) of as slag of formula _{Ca (OH) 2, Mg (} OH) The reaction promotes carbonation of Ca (OH) ₂ and Mg (OH) ₂ . In addition, the produced K ₂ CO ₃ and / or KHCO ₃ also react with unreacted CaO and MgO that have not been hydrated as shown in the formulas (33c), (33d), (34c) and (34d), and they Carbonation is promoted. Therefore, the summary reaction in (ii) above is as shown in equations (35a) and (35b).

When the hydration accelerator is NH ₃ , the hydration reaction of CaO and MgO in the slag occurs as shown in the formulas (7a) and (7b), and the hydration of CaO and MgO is promoted. Furthermore, by blowing CO ₂ into slag or warm water in which slag is immersed, it reacts with NH ₃ as shown in equations (36) and (37) to become a carbonation accelerator (NH ₄ ) ₂ CO ₃ and / Or NH ₄ HCO ₃ is produced (Note that, as shown in equations (36) and (37), carbonation of NH ₃ proceeds in the order of carbonate and bicarbonate, and the degree of progress of carbonation is Since it is determined by the amount of CO ₂ supplied and the time, even if carbonate is produced, bicarbonate may not be produced.) The (NH ₄ ) ₂ CO ₃ and / or NH ₄ HCO ₃ thus produced are Ca (OH) ₂ , Mg in the slag as shown in the formulas (38a), (38b), (39a) and (39b). _{(OH) 2} and _reacted, Ca (OH) 2, Mg _{(OH) 2} carbonation is accelerated. In addition, the produced (NH ₄ ) ₂ CO ₃ and / or NH ₄ HCO ₃ is also combined with unreacted CaO and MgO that have not been hydrated as shown in the formulas (38c), (38d), (39c) and (39d). It reacts and their carbonation is promoted. Therefore, the summary reaction in (ii) above is as shown in equations (40a) and (40b).

The aging treatment may be any of hot water aging, steam aging, atmospheric aging and the like, but hot water aging is particularly preferable because hot water containing a hydration accelerator can be repeatedly reused as described above.
In this aging treatment, the method of contacting the hydration accelerator (and the carbonation accelerator produced from the hydration accelerator) with the slag is arbitrary, but in the case of hot water aging, the hydration accelerator is added to the warm water. The slag may be aged with warm water that is added and contains the hydration accelerator (and the carbonation accelerator produced from the hydration accelerator). In the case of steam aging or atmospheric aging, in performing step (A), (i) a solution containing a hydration accelerator (such as an aqueous solution) is sprayed on the slag, and (ii) a hydration accelerator is applied to the slag. A method such as mixing, (iii) temporarily immersing the slag in a solution containing a hydration accelerator (such as an aqueous solution), or the like may be adopted.

Further, in the case where the aging treatment is performed by steam aging or atmospheric aging, in order to reuse the hydration accelerator, the hydration accelerator adhering to the slag after the aging treatment is washed away with water or the like, and the hydration accelerator is recovered. do it. On the other hand, if the hydration accelerator is not recovered and reused, the hydration accelerator component remains attached to the slag, but this hydration accelerator component is naturally carbonated by CO ₂ in the atmosphere. So there is no problem. Further, when shipping the slag early, and the like blowing CO ₂ forced carbonation with CO ₂ hydration accelerator component may be (neutralization process) is.

The treatment temperature (hydration reaction temperature, carbonation reaction temperature) of the aging treatment is not particularly limited, but is preferably about 20 to 100 ° C, more preferably about 20 to 80 ° C, and particularly preferably about 40 to 60 ° C. Therefore, hot water aging is preferable from the viewpoint of this treatment temperature.
There is no particular limitation on the treatment time (aging period) of the aging treatment, but usually, the carbonation of Ca (OH) ₂ and Mg (OH) _{2 in} the slag proceeds sufficiently, and the expansion of the slag is suppressed (water immersion expansion ratio). (Reduction of slag) and suppression of elution of highly alkaline water from slag (reduction of pH of slag elution water) can be achieved. For example, the treatment time is set so that a water immersion expansion ratio (see Examples for the measurement method) of 1.0% or less and a pH measured in the tank leaching test (see Examples for the measurement method) of 10.0 or less can be achieved. To. According to the aging method of the present invention, there is an advantage that the aging period can be significantly shortened as compared with the conventional method (simple hot water aging or steam aging).
There are no special restrictions on the equipment that performs the aging treatment, and known equipment that performs hot water aging, steam aging, etc. can be used. In the case of hot water aging, if the slag contained in one treatment tank is treated. Good.

FIG. 4 schematically shows the treatment flow of one embodiment of this aging method. In this embodiment, the aging treatment is performed by hot water aging in one treatment tank 12. Hereinafter, a case where the treatment target is slag containing CaO and NaOH is used as the hydration accelerator will be described as an example.
Slag containing CaO is put into the treatment tank 12, NaOH is added as a hydration accelerator to the warm water, and CO ₂ is blown into the treatment tank 12. In this aging method, first, CaO is hydrated by the reactions of the above formulas (1a), (2) and (3a) to generate Ca (OH) ₂ (the reaction of (i) described above). NaOH added as a hydration accelerator acts catalytically and is not consumed in the hydration reaction, but reacts with CO ₂ blown into warm water, and the NaOH is carbonated to form Na ₂ CO _3. Is generated. Then, using this Na ₂ CO ₃ as a carbonation accelerator, the carbonation of Ca (OH) _{2 in} the slag is promoted to generate CaCO ₃ (reaction of (ii) described above). Here, the reactions of the above-mentioned equations (26), (28a) and (30a) (in some cases, further equation (28c)) occur. In this reaction, NaOH as a hydration accelerator is regenerated, so that the hot water containing this hydration accelerator can be used as it is for the hot water aging of the slag of the next lot. In this case, the addition of a new hydration accelerator may only replenish the amount that is inevitably taken out of the system.

Blowing of CO ₂ for NaOH was allowed to carbonated to produce Na ₂ CO ₃ is may be performed using a gas blowing means in the processing tank 12 (FIG gas blowing means 15 in this case (Indicated by a virtual line inside), in this embodiment, CO ₂ is blown into the dedicated carbonation accelerator generation tank 13. That is, the liquid (warm water) in the treatment tank 12 is extracted and supplied to the carbonation accelerator generation tank 13 (path 18a), and the CO ₂ containing gas is supplied to the carbonation accelerator generation tank 13 to promote carbonation. Generate an agent. Then, the liquid (carbonation accelerator solution) subjected to the formation treatment of this carbonation accelerator is stored in the storage tank 14, and if necessary, a separately prepared carbonation accelerator is added to adjust the concentration, and then the treatment is performed. Supply to tank 12 (path 18b).
The slag that has undergone the aging treatment is taken out from the treatment tank 12, dehydrated in the dehydration tank 5, and then neutralized in the neutralization treatment tank 6 for the alkali content (NaOH) of the adhering water to obtain product slag. The CO _2- containing gas from the carbonation accelerator producing tank 13 is supplied to the neutralization treatment tank 6, and the alkali content (NaOH) is neutralized.

By aging free CaO and / or free MgO-containing slag such as steelmaking slag by the aging method of the present invention described above, expansion and elution of highly alkaline water can be appropriately suppressed in roadbed materials, earthwork materials, etc. Civil engineering materials can be manufactured. This civil engineering material may be used (constructed) alone or mixed with other roadbed materials (for example, other slag roadbed materials and crushed stones).
Further, the hydration accelerator for aging treatment of the present invention used in the above-mentioned aging method is a hydration accelerator for aging treatment of slag containing free CaO and / or free MgO, and is composed of NaOH, KOH, and the like. it is made of one or more selected from among NH _3.

Implementation conditions as shown below for 100 kg (dry) of steelmaking slag containing 15% by mass of soluble CaO and 5% by mass of free CaO and having a particle size adjusted to 37.5 mm or less (however, Comparative Example 5 is 100 tons). The aging process was performed in. In Invention Example and Comparative Example 1, hot water aging was performed under the condition of water / slag = 2 (mass ratio), and in Comparative Examples 2 to 6, aging treatment was performed under the condition of water / slag = 0.1 (mass ratio). Further, Comparative Example 6 is an unaged slag.
For the aged slag and the unaged slag in each example, the water immersion expansion ratio and the eluate pH were measured by the measurement methods as shown below. The results are shown in Table 1 together with the aging conditions of each example.

(1) Implementation Conditions / Invention Example 1
This is an example of the first aging method of the present invention (see the treatment flow of FIG. 1), in which NaOH (10.7 kg) is used as a hydration accelerator, and hot water aging (50 ° C.) is carried out in a hydration treatment tank for 3 days. went. The treated slag was dehydrated while neutralizing the adhering water with CO ₂ in the dehydration / neutralization tank.
-Invention Example 2
This is an example of the second aging method of the present invention (see the treatment flow of FIG. 2). After hot water aging in the hydration treatment tank under the same conditions as in the first invention, the slag is transferred to the carbonation treatment tank and carbonated. Hot water aging (50 ° C.) was performed for 3 days using Na ₂ CO ₃ (28.3 kg) as an accelerator. The treated slag was dehydrated while neutralizing the adhering water with CO ₂ in the dehydration / neutralization tank.

・ Invention Example 3
It is an example of the third aging method of the present invention (see the treatment flow of FIG. 3), and after hot water aging in the treatment tank under the same conditions as in Invention Example 1, CO ₂ containing gas (CO ₂ concentration 17 vol) in the same treatment tank. %) Is continuously blown (average CO ₂ supply amount 0.17 Nm ³ / h), and NaOH (hydration accelerator) is brought into contact with a CO _2- containing gas to generate Na ₂ CO ₃ , and this Na ₂ CO Warm water aging (50 ° C.) was further carried out for 3 days using ₃ as a carbon dioxide accelerator. The treated slag was dehydrated while neutralizing the adhering water with CO ₂ in the dehydration / neutralization tank.
・ Invention Example 4
This is an example of the fourth aging method of the present invention (see the treatment flow of FIG. 4), in which NaOH (10.7 kg) is used as a hydration accelerator, and a CO _2- containing gas (CO ₂ concentration 17 vol%) is used in the treatment tank. Was continuously blown (average CO ₂ supply 0.08 Nm ³ / h) and hot water aging (50 ° C.) was carried out for 6 days. The treated slag was dehydrated while neutralizing the adhering water with CO ₂ in the dehydration / neutralization tank.

・ Comparative example 1
Hot water aging (50 ° C.) was carried out in a hydration treatment tank for 7 days without using a hydration accelerator or a carbonation accelerator. The treated slag was dehydrated in a dehydration tank.
・ Comparative example 2
Steam aging (100 ° C.) was carried out in a reaction vessel (inner diameter 0.6 m, internal volume 0.2 m ³ ) for 3 days without using a hydration accelerator or a carbonation accelerator.
・ Comparative example 3
After performing steam aging (100 ° C.) for 3 days in a reaction vessel (inner diameter 0.6 m, internal volume 0.2 m ³ ) without using a hydration accelerator, a rotating drum type without using a carbon dioxide accelerator. Gas carbonation aging (25) by blowing CO _2- containing gas (CO ₂ concentration 17 vol%, humidity 100%) while applying rotation (10 rpm) in the reaction vessel (inner diameter 0.6 m, internal volume 0.2 m ³ ). ℃) was carried out for 3 days.

・ Comparative example 4
CO ₂ containing gas (CO ₂ concentration) while applying rotation (10 rpm) in a rotating drum type reaction vessel (inner diameter 0.6 m, internal volume 0.2 m ³ ) without using a hydration accelerator or carbonation accelerator. Gas carbon dioxide aging (25 ° C.) by blowing in (17 vol%, humidity 100%) was carried out for 3 days.
・ Comparative example 5
Atmospheric aging (25 ° C.) was carried out for 189 days without using a hydration accelerator or a carbonation accelerator.

(2) Measurement method-Water immersion expansion ratio: The water immersion expansion ratio of slag was determined based on the test method of Annex B of JIS A5015 "Road steel slag".
-Measurement of pH of elution water: Use of JIS K0058-1 "Tank leaching test method" The pH of slag elution water was measured using the test solution of the elution test as it was.

1 Hydration treatment tank 2 Carbonation treatment tank 3 Carbonation accelerator regeneration tank 4 Storage tank 5 Dehydration tank 6 Neutralization treatment tank 7 Gas blowing means 8 Treatment tank 9 Carbonation accelerator production tank 10 Storage tank 11 Gas blowing Means 12 Treatment tank 13 Carbonation accelerator generation tank 14 Storage tank 15 Gas blowing means 16a, 16b route 17a, 17b route 18a, 18b route

Claims (26)

The free CaO and / or free MgO is brought into contact with the slag containing free CaO and / or free MgO in a state where a hydration accelerator composed of one or more selected from NaOH, KOH, and NH ₃ is brought into contact with the slag. A method for aging slag, which comprises performing an aging treatment for hydrating the slag. The slag aging method according to claim 1, wherein the aging treatment is hot water aging. The second aspect of claim 2, wherein when a plurality of lots of slag are sequentially aged, the solution used for the hot water aging of the slag of one lot is used for the hot water aging of the slag of the next lot to be aged. How to age slag. The free CaO and / or free MgO is brought into contact with the slag containing free CaO and / or free MgO in a state where a hydration accelerator composed of one or more selected from NaOH, KOH, and NH ₃ is brought into contact with the slag. Step (A) of performing aging treatment to hydrate
In a state where the slag containing the hydrate of CaO and / or MgO that has undergone the step (A) is brought into contact with a carbonation accelerator composed of one or more selected from carbonates and bicarbonates. A method for aging slag, which comprises a step (B) of performing an aging treatment for carbonating the hydrate. The slag aging method according to claim 4, wherein the carbonate used in the step (B) is at least one selected from sodium carbonate, ammonium carbonate, and potassium carbonate. The slag aging method according to claim 4, wherein the bicarbonate used in the step (B) is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, and potassium hydrogen carbonate. The slag aging method according to any one of claims 4 to 6, wherein the aging treatment in the step (A) is hot water aging. When a plurality of lots of slag are sequentially aged, the solution used for the hot water aging of the slag of one lot in the step (A) is used for the hot water aging of the slag of the next lot to be aged. The slag aging method according to claim 7. The slag aging method according to any one of claims 4 to 8, wherein the aging treatment in the step (B) is hot water aging. 4. 9 of claims 4 to 9, wherein the carbonation accelerator is regenerated by blowing CO ₂ into the slag or in the warm water in which the slag is immersed during the aging treatment and / or after the aging treatment of the step (B). The slag aging method described in either. When a plurality of lots of slag are sequentially aged, the solution used for hot water aging of one lot of slag in step (B) is used for hot water aging of the slag of the next lot to be aged. The slag aging method according to claim 10. The free CaO and / or free MgO is brought into contact with the slag containing free CaO and / or free MgO in a state where a hydration accelerator composed of one or more selected from NaOH, KOH, and NH ₃ is brought into contact with the slag. Step (A) of performing aging treatment to hydrate
By contacting the hydration accelerator remaining after the completion of the step (A) with CO ₂ and carbonating it, one or more selected from carbonates and bicarbonates are produced, and the step (A) is performed. A step (B) of performing an aging treatment for carbonating the hydrate in a state where the product is in contact with the slag containing the hydrate of CaO and / or MgO that has passed through as a carbonation accelerator. A slag aging method characterized by having. The slag aging method according to claim 12, wherein the carbonate produced in the step (B) is at least one selected from sodium carbonate, ammonium carbonate, and potassium carbonate. The slag aging method according to claim 12, wherein the hydrogen carbonate produced in the step (B) is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, and potassium hydrogen carbonate. The slag aging method according to any one of claims 12 to 14, wherein the aging treatment in the steps (A) and (B) is hot water aging. The slag aging according to claim 15, wherein the aging treatment of the step (A) and the aging treatment of the step (B) are sequentially performed on the slag placed in one treatment tank by hot water aging, respectively. Method. When a plurality of lots of slag are sequentially aged, the solution used for the hot water aging of the slag of one lot in the step (B) is used for the hot water aging of the slag of the next lot to be aged. 16. The slag aging method according to claim 16. The slag aging method according to any one of claims 12 to 17, wherein in the aging treatment of the step (B), CO ₂ is blown into the slag or the warm water in which the slag is immersed. Relative to the free CaO and / or slag containing free MgO, NaOH, KOH, being in contact one or more consisting of wettable accelerator selected _from the group consisting of NH 3, slag Chumata slag is immersed A method for aging slag, which comprises injecting CO ₂ into warm water to perform an aging treatment involving the following reactions (i) and (ii) on the slag.
(I) Free CaO and / or free MgO is hydrated to obtain hydrate.
(Ii) By contacting the hydration accelerator with CO ₂ and carbonating it, one or more selected from carbonates and hydrogen carbonates are produced, and the product is used as a carbonation accelerator to produce the water. Carbonate Japanese products. The slag aging method according to claim 19, wherein the carbonate produced is at least one selected from sodium carbonate, ammonium carbonate, and potassium carbonate. The slag aging method according to claim 19, wherein the hydrogen carbonate produced is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, and potassium hydrogen carbonate. The slag aging method according to any one of claims 19 to 21, wherein the aging treatment is hot water aging. 22. Claim 22, wherein when a plurality of lots of slag are sequentially aged, the solution used for the hot water aging of the slag of one lot is used for the hot water aging of the slag of the next lot to be aged. How to age slag. The slag aging method according to any one of claims 1 to 23, wherein the slag is a steelmaking slag. A method for producing a civil engineering material, which comprises producing a civil engineering material by aging the slag by the aging method according to any one of claims 1 to 24. A hydration accelerator for aging treatment of slag containing free CaO and / or free MgO, which comprises one or more selected from NaOH, KOH, and NH ₃ for slag aging treatment water. Japanese accelerator.

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