JPH11319894A - Solidifier for sludge, molded part using this and solidification process thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solidifier used as blocks, roadbed materials or a part of other civil engineering materials by solidifying sludge, especially sludge containing fine sand or clay to attain a compression strength of 20 N/mm<2> or larger, a molding using this and a solidification process thereof. SOLUTION: This solidifier for sludge is prepared by mixing 100 pts.wt. cement, 1 to 15 pts.wt. gypsum calculated as the anhydride and 2 to 20 pts.wt. one or two or more chosen from silica fume, methakaolin and incinerated ash of silicified wood. Preferably, this solidifier is mixed in a water-to-solidifier ratio of 1.30 or smaller against the amount of water contained in the fine sand with an average particle size of 0.044 mm or smaller or in clay in the sludge, and kneaded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solidifying material for sludge and a method for solidifying the same. More particularly, sludge containing fine sand or clay is solidified among sludge to have a compressive strength of 20 N / mm ² or more, and is used for blocks and roadbeds. The present invention relates to a solidified material to be used as a part of materials and other civil engineering and building materials, a molded body using the same, and a method of solidifying the same.

[0002]

2. Description of the Related Art Conventionally, a large amount of sludge is generated in mining and washing processes of various mines or in civil engineering and construction work. In particular, in the case of construction sludge, the type of sludge may be coarse aggregate, fine aggregate or clay, or may be an arbitrary mixture of these. However, in the case of a mixture containing a large amount of fine sand or clay, the water content is as high as about 50 to 80%, so that it cannot be backfilled, and most of it is treated (discarded) as industrial waste at the final disposal site. That is the current situation. However, the final disposal site is already full, and the construction of a new disposal site has become difficult due to the emergence of public opposition to construction. Therefore, the operation of the mine is hindered as it is, and serious problems have arisen that it is not possible to order new civil engineering and construction work.

In order to solve these problems, a method of baking fine sand or clayey sludge at a high temperature of about 800 ° C. for effective use, or solidifying it with a water-soluble adhesive, and directly using a part of construction materials Methods for effective use as such have been studied. However, the method of high-temperature treatment is not directly used as a construction material, and solidification with resin is expensive, and some have a strong odor, leaving the issue of occupational health and flammability. It is difficult to use in large quantities.

The present inventor has developed a solidified material which can be used as a construction material and has a compressive strength of 20 N / mm ² or more, using a cheap and safe material, a molded body using the solidified material, and a solidifying method therefor. As a result of intensive research, they have found a method using cement as a main component and completed the invention.

[0005]

That is, the present invention provides (1) 100 parts by weight of cement and gypsum in an amount of 1 to 15 in terms of anhydride.
Parts by weight, and 2 to 20 parts by weight of one or more of silica fume, metakaolin, and incinerated ash, and (2) cement has a fineness of 2,500 to 8,000 cm. ² / g, a solidified material of the sludge according to (1), a molded product solidified using the solidified material according to (3) (1) or (2), and (4) a particle diameter in the sludge. For the amount of moisture contained in fine sand or clay of 0.044 mm or less, the solidifying material according to claim 1 or 2,
This is a method for solidifying sludge, characterized by mixing and kneading so that the water-solidifying material ratio is 1.30 or less.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The present invention is a solidifying material for sludge consisting of cement, gypsum, and one or more of silica fume, metakaolin, and incinerated ash of silicified wood (hereinafter, referred to as silica fume). This is a method for solidifying sludge by mixing fine solid or clay (hereinafter referred to as clay or the like) having a particle diameter of 0.044 mm or less in a body and sludge with a solidifying material. still,
Fine sand and clay are classified into particles of 0.05 mm or less in Japan (Agricultural Science Law of Japan), but in the cement industry there is a sieve of 0.044 mm.

The cement used in the solidified material of the present invention is various portland cement and blast furnace slag cement, and the fineness of the cement itself is important. The fineness of the cement used as the solidifying material of the present invention is 2500.
cm ² / g or more, preferably 3000 cm ² / g
The range is more preferably 4000 to 8000 cm ² / g. If the fineness is less than 2500 cm ² / g, it is difficult to obtain a strength of 20 N / mm ² or more even when the ratio of the water-solidifying material is reduced by using in combination with gypsum or silica fume, and the fineness exceeding 8000 cm ² / g. In such a case, the hydration reaction is too fast and tends to rapidly set, so that the kneading operation with a clay or the like or the forming operation becomes difficult, leading to a decrease in strength.

[0008] As the gypsum used in the present invention, one or two or more of type II anhydrous gypsum besides gypsum dihydrate, hemihydrate gypsum and type III anhydrous gypsum are used. These are mixed in an amount of 1 to 15 parts by weight with respect to 100 parts by weight of cement in terms of anhydride.
If the amount exceeds the weight part, the strength is lowered or the elongation of the strength is stagnated, which is not preferable. At room temperature, preferably 3
The range is preferably from 10 to 10 parts by weight, more preferably from 4 to 8 parts by weight, and in steam curing, the preferred range is shifted to a higher blending amount. Incidentally, more preferred gypsum is type II anhydrous gypsum,
The fineness of the gypsum has little effect on the strength and may be any value as long as it is equal to or more than that of the cement. Furthermore, in the present invention, 2 to 20 parts by weight of one or more of silica fume, metakaolin and incinerated ash of silicified wood are mixed with 100 parts by weight of cement.

[0009] Silica fume is an ultrafine powder of amorphous SiO ₂ produced as a by-product when metal silicon or ferrosilicon alloy is produced in an electric furnace. Metakaolin is a material obtained by firing clay such as kaolin at about 800 ° C. Aluminosilicate fine powder. The incinerated ash of silicified wood is ash when silicified wood such as rice, straw and bamboo is baked, and is amorphous SiO ₂ . All have strong pozzolanic activity and react with Ca (OH) ₂ generated by hydration of cement to solidify. When the amount is less than 2 parts by weight, the strength enhancing effect is small even when used in combination with gypsum, and no further strength enhancing effect is exhibited even when added in excess of 20 parts by weight, preferably 4 parts by weight or more. Preferably it is 5 to 10 parts by weight.

In the practice of the present invention, as described above,
Sludge is often not only clay or the like but also an arbitrary mixture with coarse sand or gravel. Therefore, the amount of clay and the like and the composition ratio of coarse sand and gravel are measured by a particle size test, and the amount of solidifying material is added to the amount of clay and the like, and the ratio of water-solidifying material is 1.30.
Adjust so that: At this time, the water to be reacted with the solidifying material uses water in clay or the like, and no new water is added. The water-solidifying material ratio means that the particle diameter in the sludge is 0.044.
It is the ratio between the amount of water contained in fine sand or clay of less than mm and the amount of solidifying material used, and is a weight ratio.

When the water solidifying material ratio (weight ratio) exceeds 1.30, it is difficult to obtain a strength of 20 N / mm ² or more, and preferably about 1.0 or less. And the strength becomes higher as the water-solidifying material ratio is smaller, but the water-solidifying material ratio is adjusted by the amount of the solidifying material. Therefore, the water-solidifying material ratio is preferably 0.25 or more.

In the practice of the present invention, it is preferable to add an appropriate amount of aggregates such as fine aggregate and coarse aggregate separately from those contained in clay or the like when forming a molded body. Fine aggregate is coarse sand of more than 0.044 mm and 5 mm or less,
Coarse aggregate is gravel exceeding 5 mm and 40 mm or less.
The reason why the coarse aggregate exceeding 40 mm is excluded is that the thickness of the precast product is generally not as thick as mass concrete, so that an aggregate larger than the thickness becomes a defective portion such as strength. If it is previously contained in clay or the like, it is removed by sieving in the manufacturing process. These aggregates increase the mixing efficiency of the clay or the like and the solidified material, and enhance the dispersing effect of the solidified material, thereby increasing the strength. In addition, a cured product consisting only of fine particles consisting of clay and solidified material has a high structural sensitivity and is brittle even if the strength is high, and the amount of sand helicopter (physical properties required for roadbed materials, etc., tested with a Los Angeles tester for aggregate) On the other hand, the addition of the aggregate reduces the structural sensitivity, and also provides stable high strength and shear resistance. Further, the addition of the aggregate is economically preferable because the amount of the finished product increases because it is added to the amount of the clay or the like to be treated and the amount of the solidified material.

As the aggregate, natural products, various types of artificial aggregates and slags are used, and there is no particular limitation as long as it has a quality generally usable for mortar and concrete. Mixing ratio of these aggregates (including those already contained in the clay are also taken into account)
Is fine aggregate 30 to 100 parts by weight of clay etc.
300 parts by weight are blended and mixed. If the fine aggregate is less than 30 parts by weight, the mixing efficiency is poor and the strength is not increased, which is not preferable. If the amount exceeds 300 parts by weight, molding becomes difficult, which is not preferable. The preferred amount of fine aggregate is 50 parts by weight or more, more preferably 70 to 150 parts by weight.
In the case of coarse aggregate, any amount may be used as long as it can be molded.
In addition, coarse aggregate exceeding 40 mm is removed by sieving in the process of manufacturing the molded body.

In the solidification method of the present invention, for mixing, a forced kneading mixer for concrete, a kneader or another kneading device is used. At first glance, these kneaded mixtures are in a state of being dry, but they are put into a mold and compacted by tamping, pressurized, or pressed by vibration to obtain a product. The curing method after molding may be air-dry or wet curing at room temperature until the strength is developed, or steam-cured at any time or material age to develop the strength.

A description will be given of how a solidifying material is added to actual sludge and treated. (1) If the sludge is entirely clayey and does not contain fine or coarse aggregates, first sample it from any location so that it is average, mix it, and mix it at 150 ° C.
The amount of change in weight with respect to the drying time is 1 wt. % And dried to obtain the water content of the clay. Then, the solidifying material is mixed with 100 parts by weight of the clay, and if necessary, fine aggregates and coarse aggregates are blended in an appropriate amount, kneaded and molded. The sampling amount for drying in this case is 500 g to 1000 g. (2) If the sludge optionally contains fine aggregate or coarse aggregate, first sample from an arbitrary point so as to obtain an average, knead and mix it, weigh out an appropriate amount, and dry at 150 ° C. To determine the total water content. In this case, the sampling amount for drying varies depending on the size of the coarse aggregate mixed, but is 1 kg to 10 kg. Separately, an appropriate amount of the kneaded mixture is weighed, an appropriate amount of water is added to suspend the mixture, and sieves of 0.044 mm, 5 mm, and 40 mm are stacked, and the suspension is sieved. Fine aggregate of 5 mm or less remaining on a 0.044 mm sieve, 40 m remaining on a 5 mm sieve
m or less is defined as coarse aggregate, and the composition weight of 0.044 mm or less of clay or the like, including coarse aggregate remaining in a 40 mm sieve, is expressed in percentage. At this time, for fine aggregate, coarse aggregate, and aggregate exceeding 40 mm, the weight measured by adjusting the surface to a dry state is used. Each component is obtained from the following equation. Clay amount = total amount− [total amount of surface-dried fine aggregate, coarse aggregate, and aggregate exceeding 40 mm] / total amount × 100 fine aggregate amount = total amount− [clay amount, coarse aggregate amount, And 40mm
The total water content of the clay alone is calculated from the total loss on drying by subtracting the water content of fine aggregate, coarse aggregate, and aggregate exceeding 40 mm by 2 watts.
t. % Constant, calculated from the composition amount, and subtracted from the total dry weight. Also, at the time of production of the molded body, after adding fine aggregate and coarse aggregate (more than 5 mm and not more than 40 mm) in clay or the like, an appropriate amount of fine aggregate and coarse aggregate are newly added and the solidified material is added. Knead with it. Since this mixture is in a state free of moisture of lumps, it is sieved with 40 mm to obtain 40 m.
Large aggregates larger than m can be easily removed before molding.

Hereinafter, the present invention will be described in detail with reference to Examples, but it should not be construed that the invention is limited thereto.

[0017]

EXAMPLES Example 1 A solidified material having an arbitrary composition, a clay having a moisture content of 65% (44 μm, 0.044 mm through the water, no coarse sand or gravel) collected from a marsh, Using river sand in a dry state for concrete (5 mm below) as an aggregate, the mixture was kneaded with a mortar mixer for JIS mortar for 5 minutes while arbitrarily changing each ratio. Knead the mixture to φ5
It was placed in a mold frame of × 10 cm, and was formed by squeezing several layers by human power using a cut surface obtained by cutting a round steel of φ12 mm.
The molded body was removed from the mold after 3 days, and air-cured in a room at 20 ° C., and the compressive strength of a 28-year-old material was measured. The results are shown in Tables 1 and 2. The materials used are as follows.

<< Components of solidifying material >> Cement Ordinary Portland cement clinker as SO ₃
%, And a cement with various fineness (Brain method, porosity 0.5) was mixed with a vibrating pot mill, and partially added with SO ₃ as SO _3.
% Blast-furnace granulated slag powder (pulverized to a fineness of 5050 cm ² / g)
The blast furnace slag cement mixed with was used. a. 2090 cm ² / g (normal cement) b. 2500 cm ² / g (normal cement) c. 3080 cm ² / g (normal cement) d. 4050 cm ² / g (normal cement) e. 5100 cm ² / g (with 45% blast furnace slag powder blended) f. 6090 cm ² / g (normal cement) g. 7120 cm ² / g (normal cement) h. 7990 cm ² / g (normal cement) i. 9200cm ² / g (normal cement)

Gypsum A. Insoluble anhydrous gypsum generated by hydrofluoric acid (fineness: 3010cm
² / g) B. Industrial dihydrate gypsum ground (5300 cm fineness)
² / g) C.I. B is heat treated and pulverized as hemihydrate gypsum (fineness 100
00 cm ² / g or more) B is heat-treated and pulverized as soluble anhydrous gypsum (fineness: 10,000 cm ² / g or more)

Silica fume etc. a. Silica fume (commercially available, fineness: 23 m ² / g) b. Metakaolin (commercially available, fineness: 8000 cm ² /
g) C. Straw ash (fineness 1.2m ² / g)

[0021]

[Table 1]

[0022]

[Table 2]

From Tables 1 and 2, it was found that Experiment No. 1-1 comparison
In the example, even if the cement fineness is appropriate, only low strength
While the solidification material of the present invention cannot be obtained,
The strength greatly depends on the degree. Used for solidifying material
Fineness of cement is 2000cm^Two/ G (Experiment No. 1)
-2, 10 N / mm in Comparative Example)^TwoOnly strong strength can be obtained
There is no 2500cm^Two/ G or more suddenly
Increase to 20 N / mm ^TwoTo obtain the above strength
The higher the fineness, the higher the value. Also,
Even if too high, cement hydrates quickly and inadequate compaction
It is also shown that the strength drops sharply as a result (actually,
Experiment No. 1-10, comparative example).

In the present invention, the fineness of the cement is 2
500 cm ² / g or more, preferably 3000 cm ² / g
Above, more preferably 4000 to 8000 cm ² / g
(Experiment Nos. 1-3 to 1-9).

Further, the gypsum alone does not exhibit a strength of 20 N / mm ² or more regardless of the amount of the gypsum (Experiment No. 1-11-1-19). Even in the case of silica fume, etc., regardless of the blending amount, 20 N / mm
^No strength of ² or more is shown (Experiment Nos. 1-20 to 1-
26).

The combined use of gypsum and silica fume synergistically increases the strength, and a combined strength of 1 part by weight and 2 parts by weight or more enables a high strength of 20 N / mm ² or more to be obtained (Experiment No. 1). -27 to 1-34). And although each is a single addition, gypsum is preferably 3-1.
0 parts by weight, more preferably 4 to 8 parts by weight (Experiment No. 1)
-11 to 1-19), and silica fume and the like are preferably at least 4 parts by weight, more preferably 5 to 10 parts by weight (Experiment Nos. 1-20 to 1-26). It is preferable to use both in the range.

The water-solidifying material ratio is 20 N / m at 1.30 or less.
A strength of at least m ² can be obtained, and is preferably about 1.0 or less. The strength increases as the ratio of the water-solidifying material decreases, but the strength decreases when the ratio is too small. This is because if the amount of the solidifying material is too large, the moldability deteriorates.
5 or more (Experiment Nos. 1-35 to 1-
42).

The addition of fine aggregate increases the strength by increasing the dispersibility of the solidified material in the clay. The greater the amount of fine aggregate, the higher the strength. Drops. The effect is exhibited when the amount of fine aggregate is 30 to 300 parts by weight, preferably 50 to 200 parts by weight, more preferably 7 to 300 parts by weight.
0 to 150 parts by weight (Experiment Nos. 1-49 to 1-5)
5).

Example 2 Experiment No. 1 of Example 1 1-1 and No. 1 Using 1-52, 25 to 5 mm and 40 to 5 mm in the standard particle size in the surface dry state
The amount of the coarse aggregate (crushed stone) was changed, and a total of about 30 liters of clay, solidified material, fine aggregate and coarse aggregate were kneaded for 5 minutes using a planetary forced kneading mixer having a capacity of 50 liters. The specimen was formed into a mold having a diameter of about 12.5 ± 25 cm and a height of about 23 cm. The forming method uses a φ12 mm steel rod with a φ5 × 10 cm cylinder welded to the tip, squeezes it into several layers, and finally applies a φ12 × 5 cm iron plate and presses the whole with a pressure of 20 tons. did. Curing was performed 4 hours after the preparation of the test specimen, raised to 75 ° C. in 3 hours, kept for 5 hours, and then gradually cooled down to the next day by closing the steam valve and demolding. Then, it was cured in a room air and the compressive strength was measured at the age of 7 days. Table 3 shows the results.

[0030]

[Table 3]

From Table 3, it can be seen that the addition of an appropriate amount of coarse aggregate not only has the meaning of a filler but also increases the strength. This is presumed that stacking of coarse aggregate contributes to strength.

[0032]

As described above, the present invention makes it possible to solidify fine sand and clay-like fine particles having a high water content, which are the most difficult to solidify among the sludges generated in mining and construction work. And the strength can be increased to a level usable for construction materials. Therefore, it is not necessary to treat the sludge as industrial waste, and the sludge is given added value and the environment is prepared.

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Claims (4)

[Claims] 1. 100 parts by weight of cement, 1 to 15 parts by weight of gypsum in terms of anhydride, and one or two or more of silica fume, metakaolin, and incinerated ash of silicified wood
A solidification material for sludge, which is blended in an amount of 20 parts by weight. 2. The cement has a fineness of 2500 to 8000 c.
^2. The sludge solidifying material according to claim 1, wherein the sludge is m ² / g. 3. A molded article solidified using the solidifying material according to claim 1. 4. The method according to claim 1, wherein the amount of water contained in the fine sand or clay having a particle diameter of 0.044 mm or less in the sludge is reduced.
A method for solidifying sludge, comprising mixing and kneading the solidified material described above so that the water-solidified material ratio is 1.30 or less.