JPH07188657A - Material and method for soil improvement - Google Patents

Abstract

PURPOSE:To obtain a soil-improving material excellent in capability of stabilizing a soft ground by mixing CaO-, SiO2-, and Al2O3-supplying materials, hydrating the mixture, using it for treating a flue gas, and if necessary adding a lime-derived. alkaline substance to it. CONSTITUTION:A calcium oxide-supplying material (e.g. hydrated lime), a silicon dioxide supplying material (e.g. calcium silicate), and an aluminum oxide- supplying material (e.g. alumina) are mixed and hydrated. The resulting compsn. is used for treating a flue gas contg. oxygen, water. nitrogen oxides, and sulfur oxides or a flue gas contg. oxygen, water, nitrogen oxides, sulfur oxides, and hydrogen halide compds. Then the compsn., if necessary after mixed with a lime-derived alkaline substance (e.g. slaked lime), is used as a soil-improving material. The material in an amt. of 1-10 pts.wt. is mixed into 100 pis. wt. soft soil to improve a soft ground.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft ground improvement material and method.

[0002]

2. Description of the Related Art Cement-based soil conditioners or calcareous soil conditioners have been used for the improvement of soft ground.
However, for example, it is impossible to sufficiently exert the effect on loamy soil.

It is known that a lime-gypsum type soil conditioner obtained by adding dry gypsum to a calcareous soil conditioner is effective. However, since it is difficult to obtain inexpensive dry gypsum,
There is a method such as mixing and using quicklime and hydrous gypsum at the site of soil improvement work, and there are problems with the mixing ratio and the uniformity of mixing, and the effects vary.

Therefore, there has been a demand for an inexpensive improving material having performance comparable to that of the lime-gypsum type soil improving material.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a ground improvement material and a ground improvement method which can meet the above-mentioned demand.

[0006]

Means for Solving the Problems As a result of various studies to achieve the above-mentioned object, the inventors have surprisingly found that a lime composition which the inventors have already developed as a flue gas treatment agent is a flue gas. It was found that adding lime alkaline substances after treatment or after smoke treatment is effective for ground improvement.

That is, according to the present invention, a composition obtained by mixing and hydrating a substance which is capable of supplying calcium oxide, silicon dioxide and aluminum oxide as a main raw material is oxygen,
Ground improvement material used for the treatment of flue gas containing water, nitrogen oxides, sulfur oxides, or hydrogen halide compounds in addition to these, or ground improvement material obtained by adding a lime alkali substance, and soft soil to these ground improvement materials. It is a ground improvement method characterized by mixing with.

Examples of substances which can supply calcium oxide in the present invention include quick lime, slaked lime, lime carbonate, cement, slag, dolomite plaster (containing lime), and by-products such as acetylene slag.

The substances which can supply silicon dioxide are, for example, silicic acid, hydrous silicic acid, metasilicic acid, aluminum silicate, calcium silicate and cristobalite, tridymite, kaolin, bentonite, talc, perlite, shirasu, diatomaceous earth, glass, fir tree. Examples thereof include compounds containing reactive silicon dioxide such as incinerated ash such as shell ash and wood ash.

Examples of substances that can supply aluminum oxide include alumina, aluminum hydroxide, aluminum silicate, alum sulfate, alum, aluminum sulfide, aluminum sulfate, aluminum chloride, calcium aluminate, bentonite, kaolin, diatomaceous earth, Examples thereof include compounds containing reactive aluminum such as zeolite, perlite, bauxite, sodium aluminate, and quartz.

In addition to the main raw materials capable of supplying the above-mentioned three kinds of metal oxides, sulfuric acid compounds, halogen element compounds, sulfides,
It is also possible to add one or more substances selected from the group of substances capable of supplying hydroxides of alkali metals.

The substance capable of supplying a sulfuric acid compound or a halogen element compound is a substance produced by combining an alkaline earth metal such as calcium and magnesium, an alkali metal such as sodium and potassium, and sulfuric acid and hydrogen halide. , Calcium sulfate, magnesium sulfate, calcium chloride, magnesium chloride, sodium sulfate, calcium sulfite, calcium hydrogen sulfate, sodium chloride, strontium chloride, calcium bromide, calcium iodide, potassium chloride, sodium thiosulfate, sodium hydrogen carbonate, hydrogen carbonate Examples include calcium.

Examples of substances that can supply sulfides include calcium sulfide, iron sulfide, and zinc sulfide.

Examples of the substance capable of supplying the hydroxide of an alkali metal include sodium hydroxide and potassium hydroxide.

Furthermore, by adding elemental sulfur, for example, to the required materials described above, mutual reaction between the materials proceeds, and as a result, calcium sulfide, calcium sulfate, etc. are produced and supplied. In this case, water glass produced by the reaction of silicon and caustic is also included.

Further, examples of other substances capable of simultaneously supplying two or more of the above-mentioned at least three metal oxides include coal ash and volcanic ash, coal fluidized bed combustion ash (calcium oxide, silicon dioxide, aluminum oxide, Calcium sulfate, sodium sulfate, potassium sulfate source), cement and cement clinker (calcium oxide, silicon dioxide, aluminum oxide source), slag and silas, andesite, chert, quartz trachyte, opal, zeolite, feldspar, clay mineral, ettringite Reactive silicon dioxide such as (calcium sulfate, silicon dioxide, aluminum oxide, calcium oxide source), minerals containing sodium, aluminum, calcium, etc. and chlorides, sulfate, etc., in-furnace desulfurized ash such as fluidized bed combustion ash and Used desulfurization agent after flue gas desulfurization,
Examples of waste include sludge incineration ash, municipal waste incineration ash, cement waste, acetylene slag, and used wastewater treatment agent.

Here, the used desulfurizing agent means JP-A-61-2.
09038, 62-97640, and 62-25482.
4, said 63-283745, said 64-38130, and the used ones of the calcium-based flue gas treatment agents disclosed in JP-A-4-271811.

The ground improvement material of the present invention comprises, in combination with the above materials, at least 1% of CaO, 1% of SiO ₂ , 1% of Al ₂ O ₃ and 1% of a sulfuric acid compound, a halogen element compound, a sulfide and / or an alkali metal. As hydroxide
0.1%, preferably 1 to 80% as CaO, 5 to 90% as SiO ₂ , 5 to 90% as Al ₂ O ₃ , and 1% of CaSO ₄ , Na ₂ SO ₄ , CaCl ₂ , and NaCl.
If more than one species is selected, these are
0.1 to 70% CaS is selected 0.1 to 50% NaOH is selected 0.1 to 10% of the composition used for flue gas treatment,
Alternatively, a lime alkaline substance is added to it.

The hydration treatment in the present invention means a treatment necessary for promoting the hydration reaction between the above-mentioned various substances (raw materials), for example, normal pressure or high pressure normal temperature water or wet air curing, steam curing. Or hot water curing is included.

In the curing step, after a sufficient amount of water necessary for the production of the active substance for flue gas treatment in the composition is provided, the important step of forming the active compound necessary for flue gas treatment is completed, During this time, some or most of the water content
It is consumed in the compound forming reaction.

The non-consolidating hydration treatment is a treatment for preventing the material particles from binding to each other during the hydration treatment to grow into coarse particles, and the solid-liquid ratio at the start of the treatment is increased to, for example, 1: 1. : 1 to
It is 1:20, and in hot water curing, the raw material is dispersed in water at 40 ° C to 180 ° C, and stirring, bubbling, circulation, shaking, etc. are performed for several minutes to several days so that the raw material does not precipitate and harden in the lower part. is there.

Curable hydration treatment is to reduce the solid-liquid ratio at the time of kneading, for example, 1: 0.2 to 1: 0.99 to promote the bonding between material particles and obtain a cured product. Hydration process.

Moist air curing at a temperature of 10 ° C to 40 ° C and relative humidity of 50% to 100% for a few minutes or several picking days is preferable, and steam curing at a temperature of 40 ° C to 180 ° C and relative humidity of 100%. It is preferably several minutes to several days.

The cured product after curing is adjusted by adjusting the water content as necessary and crushed by a conventional method, for example, to obtain a coarse particle (about 0.5 mm to
(Several millimeters) and pulverized to obtain fine particles (approximately 0.5 mm or less, several microns or more).

The slurry-like substance (extremely fine particles, several microns or less) obtained by the non-consolidating hydration treatment can be used as it is for flue gas treatment.

Curing for obtaining coarse particles and fine particles is
It can also be performed in the following two stages.

The condition of the first stage wet air curing is a temperature of 10 ° C.
At a temperature of -40 ° C and a relative humidity of 50% to 100%, a period of several minutes to several days is preferable. Also, steam curing is performed at a temperature of 40 ° C to 180 ° C.
It is preferable that the temperature is 100 ° C. and the relative humidity is 100% for several minutes to several days.

In the first stage curing, after completion of the curing, the mixture in which the partial hydration reaction is progressing is easily formed from a fine particle size to a coarse particle size, granulated, or a cured product is crushed. In order to achieve this, conditions are set such that the water content and the curing state are appropriate.

That is, the first stage curing is to promote the hydration reaction for forming the active compound in the initial stage necessary for molding and granulating the raw material mixture, and the used desulfurizing agent is used as the raw material. , Spent wastewater / exhaust gas treatment agent, activated CaSO ₄ , SiO ₂ , Al ₂ O ₃ , CaC such as fluidized bed combustion ash
When a substance containing 1 ₂ or the like is used, or when a reactive substance such as cement is added, or when a substance such as CaO that hydrates, generates heat or decomposes is used, the initially added material May change or become finely powdered, and the temperature of the mixture during kneading may rise, so that the hydration reaction may significantly progress even while the raw materials are being kneaded. For this reason, it is possible to obtain an appropriate water state for forming and granulating, which is the object of the first stage curing proposed by the present invention. When the hydration reaction significantly progresses during kneading as described above, this kneading is the first stage curing.

If desired, the material that has undergone the first stage curing is molded (granulated) by a briquette machine, pelletizer, or the like.
Since the process has been completed, particles having a particle size that can be dispersed in water can be easily obtained with high yield. The molded product can be subjected to a second stage curing, sized, and then subjected to flue gas treatment.

The second stage curing is 10 ° C. for wet air curing.
-40 ° C, relative humidity 50% to 100%, preferably several minutes to several pick-up days, and steam curing at a temperature of 40 ° C.
It is preferably from 180 to 180 ° C. and 100% relative humidity for several minutes to several days. When a coarse particle or fine particle flue gas treatment composition is produced by one-time curing, it is carried out in the same manner as in the second step.

Next, the production of the composition used for the flue gas treatment of the present invention will be described. If necessary, the above raw materials are ground and mixed, and then water is added and mixed. The water-soluble salts in the raw material are preferably used by dissolving them in water to be added. The water content of the raw material mixture after the addition of water is 20 to 2000 parts by weight, preferably about 30 to about 1 per 100 parts by weight of the dry matter.
000 parts by weight. Since this water naturally contains water derived from the raw materials, the use of dilute sulfuric acid, dilute hydrochloric acid or the like may cause the case where the addition of water is unnecessary.

Next, the mixture is subjected to a hydration treatment, that is, a hot water curing by heating in a humid air or water at room temperature or steam or steam heating. Further, it can be similarly performed under high pressure.

When the hydration treatment is a non-consolidating hydration treatment, the composition is dehydrated, dried, and conditioned to obtain a smoke exhausting treatment composition as it is, or further as it is or crushed and crushed and then molded. The composition as a molded body can be obtained.

When the hydration treatment is a curable hydration treatment, the cured product is dried, conditioned, pulverized, or further molded,
A composition is obtained.

Crushing of a hardened product which has been wet or dried, compression molding of a crushed product and a dried product of a slurry-like substance can be carried out by using a marmelizer, a disk pelleter, a briquette machine, a tablet molding machine, an extrusion molding machine, or the like. This can be done by the compression moldable equipment used.

The composition described above is then subjected to a known flue gas treatment. Gas components in flue gas, oxygen, water (water vapor), nitrogen oxides and sulfur oxides, or are those further containing hydrogen halide compound to, flue gas desulfurization and de NO _x and de This process Halide is carried out.

The composition after flue gas treatment can be used as it is or by adding a lime alkaline substance to the composition to obtain the ground improvement material of the present invention. Here, the lime alkaline substance is quicklime,
Slaked lime, calcium carbonate, waste alkali containing calcium,
It refers to cement and the like, and of these, quick lime, slaked lime, and cement are preferable.

In order to add the lime alkaline substance, a method of directly powder-mixing the two is adopted. In this case, the amount of the lime alkaline substance added is 10% by weight of the dry matter of the composition to be added.
It is 90 parts by weight or less in terms of quick lime with respect to parts by weight.

The particle size of the ground improvement material of the present invention is not particularly limited, but is preferably 50 mm or less, preferably 20 mm or less, more preferably 5 mm or less, and the water content is 20% or less.

In order to treat soft soil using the ground improvement material of the present invention, there may be adopted a road mixing method, a soil collecting method mixing method and a plant mixing method which are known as the methods for carrying out the lime stabilization treatment.

[0042]

【Example】

Example 1 To 30 parts by weight of coal ash (overseas) B shown in Table 1, 50 parts by weight of slaked lime, 20 parts by weight of spent flue gas treatment agent (used desulfurization agent) and 200 parts by weight of water were added and kneaded to perform steam curing. 10
It was carried out at 0 ° C. for 12 hours to obtain a slurry composition having a composition concentration of 30%. This slurry was sprayed into the exhaust gas under the conditions shown in Table 2 to carry out smoke exhaust treatment.

[0043]

[Table 1]

[0044]

[Table 2] 70 parts by weight of powdered quick lime was added to 30 parts by weight of the powdery substance (water content 1%) after the flue gas treatment and mixed by a mixer to obtain a ground improvement material of the present invention. The analytical values of this material are shown in Table 3 together with the values of other examples.

[0045]

[Table 3] Next, the performance test of the ground improvement material was conducted as follows. Two types shown in Table 4 were used as the soil (target soil) to be improved, and 100 parts by weight of the soil improvement materials 1, 3 and 5 were used.
Parts (parts 1-1, 1-2, and 1-3) mixed with parts by weight and mixed with a mixer for about 5 minutes were filled in a frame having a diameter of 5 cm and a height of 10 cm, and allowed to stand at room temperature for 10 days. The uniaxial compressive strength was measured. The measurement results are shown in Table 5 together with other examples and comparative examples.

[0046]

[Table 4]

[0047]

[Table 5] Example 2 A ground improvement material was obtained in the same manner as in Example 1 except that slaked lime was used instead of quicklime, and the same soil treatment and performance test as in Example 1-2 were performed. Example 3 30 parts by weight of coal ash (overseas) B shown in Table 1 was added with 30 parts by weight of slaked lime, 40 parts by weight of used flue gas treatment material A and 45 parts by weight of water, and after kneading, until strength enough to withstand molding. Curing in damp air. Next, extrusion molding is performed and steam curing is performed at 90 to 100 ° C. for 12 hours. Using the particulate composition (5 to 6 mm) obtained by sizing and drying this cured product, flue gas treatment was performed under the conditions shown in Table 6.

[0048]

[Table 6] The used flue gas treating agent obtained by the flue gas treatment is roughly crushed to 2 mm or less, and 30 parts by weight thereof is mixed with 70 parts by weight of quick lime to obtain the ground improvement material (water content 1%) of the present invention. It was This soil improvement material was subjected to the same target soil treatment and performance test as in Example 1-2. Example 4 The used particulate flue gas treating agent obtained in Example 3 was pulverized to a powder of 0.05 mm or less, and 30 parts by weight of quicklime 7
The ground improvement material of the present invention was obtained by mixing 0 parts by weight, and the same mixing treatment and performance test as in Example 1-2 were performed. Example 5 70 parts by weight of slaked lime was added to and mixed with 30 parts by weight of the powdery spent flue gas treating agent obtained in Example 4 to obtain a ground improvement material of the present invention. This ground improvement material was subjected to the same mixing treatment and performance test as in Example 1-2. Example 6 66 parts by weight of coal ash (Japan) A shown in Table 1, 30 parts by weight of slaked lime, 4 parts by weight of calcium chloride and 35 parts by weight of water were added and kneaded, followed by extrusion molding, and steam curing at 95 to 100 ° C. To do. The cured product thus obtained is sized,
After drying, the exhaust gas treatment was performed under the conditions shown in Table 7.

[0049]

[Table 7] The used flue gas treating agent obtained by flue gas treatment in this way is 0.0
A powder of 5 mm or less was mixed, and 30 parts by weight of the powder was mixed with 70 parts by weight of quicklime to obtain a ground improvement material of the present invention.
The target soil was treated in the same manner as above and a performance test was conducted. Example 7 In Example 1, the powdery substance after the flue gas treatment was used as the ground improvement material of the present invention, and the same soil treatment as in Example 1-2,
Uniaxial compressive strength measurement was performed. Comparative Examples 1 to 6 The target soil was treated in the same manner as in Example 1-2 for the samples shown in Table 9 using the commercially available lime-based ground improvement material shown in Table 8.

[0050]

[Table 8]

[0051]

[Table 9] The general standard for improved ground is that it does not hinder the operation of trucks, and when expressed in uniaxial compressive strength, it is 1.5 kgf / cm.
^{Although it is 2} or more, it is clear from the above Examples and Comparative Examples that the ground improvement material of the present invention is extremely effective for ground improvement by giving sufficient strength to the target soil by the mixing treatment.

[0052]

As described above, the ground improvement material of the present invention utilizes a lime-based spent smoke treatment agent, and it is easy and effective to improve soil quality of soft ground containing water. You can eat it, and the effect is great.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Tsutomu Ueno, 1-2 Odorihigashi, Chuo-ku, Sapporo-shi, Hokkaido Within Hokkaido Electric Power Company (72) Yutaka Kitayama, 1-2 Odori-higashi, Chuo-ku, Sapporo, Hokkaido Hokkaido Electric Power Within the corporation

Claims (5)

[Claims] 1. A composition obtained by mixing and hydrating a substance capable of supplying calcium oxide, silicon dioxide and aluminum oxide as a main raw material, oxygen, water, nitrogen oxide, sulfur oxide or oxygen, water, nitrogen. A ground improvement material used for treating flue gas containing oxides, sulfur oxides, and hydrogen halide compounds, either as it is or with the addition of lime alkaline substances. 2. The hydration treatment is a non-consolidating hydration treatment, and after the treatment, dehydration, drying, and humidity control, as it is or by crushing,
The ground improvement material according to claim 1, which is formed into a molded body after crushing. 3. The hydration treatment is a curable hydration treatment,
The ground improvement material according to claim 1, which is used as it is or after being treated, dried, moisture-conditioned, and pulverized to obtain a molded body. 4. A ground improvement method, which comprises mixing the ground improvement material according to claim 1 with soft soil. 5. The ground improvement method according to claim 4, wherein the weight mixing ratio of the soft soil and the ground improvement material is 100: 1 to 10.