JPS6045960B2 - Consolidation material for sludge - Google Patents

Description

[Detailed description of the invention] The present invention relates to a consolidation material for sludge.

Sludge that has settled on the bottom of rivers, industrial waste sludge containing heavy metals, sludge from water treatment plants and sewage treatment plants, and sludge made of moist clay often contain components that are harmful to the human body or emit odors. Since this may occur, there is a strong need for an appropriate and effective treatment method. For example, to explain the problem of sludge treatment at a water treatment plant, the quality of the raw water supplied in the past was good and the concentration of suspended solids contained was extremely low. However, recently, the concentration of suspended solids in raw water has increased, and the amount of sludge due to this has increased significantly.At the same time, there are various restrictions on diluting and discharging this sludge back into rivers. I started receiving it.

In particular, there are even more stringent requirements for industrial waste containing hazardous substances such as heavy metals. Conventionally, methods of treating this sludge have been proposed, such as dewatering the sludge, solidifying it into a cake shape, and dumping it, or solidifying it with hydraulic materials such as cement or quicklime. In addition to restricting dumping locations, measures must be taken to prevent the waste from flowing out again due to rain.

On the other hand, the latter method can eliminate these drawbacks, but sludge generally contains fine particles such as clay and organic matter in a large amount of water, so sludge cannot be hardened by hydration of cement or quicklime. It is difficult to proceed, and the hardness of the hardened material is low, so in order to harden it to the required strength, or to use it as a material for landfill or civil engineering construction, large amounts of cement and quicklime must be mixed with sludge. The disadvantage was that it had to be mixed with In order to solve these drawbacks, a setting material made by blending cement with a mixture of calcium aluminate minerals and inorganic sulfates has been proposed (Japanese Patent Application Laid-Open No. 1983-1999).
133167), but it still cannot be said to be sufficient.

As a result of various studies on caking materials that can be made into a strong hardened body by dispersing and mixing a small amount in sludge, the present inventor found that 3Ca0
-3A1.03・CaSO4 or 3Ca03A1203
- The present invention was completed after discovering that a hydraulic composition containing CaF2, quicklime, and calcium sulfate has an outstanding effect for this purpose.

The present invention will be explained in detail below. In the present invention, 3Ca0
-3A1203.CaSO4 is a mineral called Auin, and can be used regardless of whether it is a natural product or a synthetic product. As the calcium sulfate, various calcium sulfates such as anhydrite, hemihydrate, and dihydrate can be used, but anhydrite is preferable. It is also possible to use sodium sulfate. Among these, certain combinations are generally used as cement expansion agents and are said to produce ettringite when hydrated, and specific examples include the trade names Denka CSA and Asano dypcal.

The preferred proportions of these three components are 3 to 40% by weight of Auin, particularly preferably 10 to 40% by weight, and 5 to 35% by weight of quicklime.
Particularly preferably 10 to (i) weight % and calcium sulfate 30 to 7 weight %, particularly preferably 40 to 6 weight %. In order to obtain a consolidation material with these compositions, it is necessary to prepare each of these components in advance and mix them in a certain amount, or to mix the raw materials for the Al2O3 source, CaO source, and SO3 source so that they have approximately the desired composition. 1200~14
There is a method of firing at a temperature of about 00°C. Furthermore, even if a compound called 3Ca0-3A1203.CaF2 is used instead of Auin, the effect is almost the same as when Auin is used. No restrictions on fineness, plain value 200
Approximately 0 cd1y is sufficient. The caking material of the present invention produces ettringite in a large amount and in a short period of time, thereby improving sludge treatment efficiency, compared to that described in JP-A-50-133167.

The reason for this is that compared to cement, quicklime produces slaked lime with a large surface area (high hydration activity) in a short time and with a large amount of heat generation, which significantly increases the reaction with auin and calcium sulfate. be. When using the caking material of the present invention, it is sufficient to mix and disperse it into sludge, and the method can be freely selected from either the normal batch mixing method or continuous mixing without requiring any special means. I can do things.

Next, the usage amount of the consolidation material of the present invention will be explained.

Sludge water content ratio WIS is generally used for sludge that requires solidification treatment.
(W: water, S: solid content) is 5% or more in heel weight,
Often, the amount is more than 10%. The amount of the sludge of the present invention required to solidify the sludge is closely related to the amount of water contained in the sludge. Consider and add the required amount. Specifically, if the amount used is too small relative to the water in the sludge, the purpose of solidification will not be achieved at all, so it is usually used in an amount of 5% by weight or more relative to the amount of water in the sludge. Furthermore, it is desirable to use it for promoting the solidification of sludge whose water content is 5% or less. According to the present invention, it is possible to solidify sludge with a small amount of use, and its strength is also high.Also, in the case of solidified sludge containing heavy metals, there is an advantage that the outflow of heavy metals after solidification is extremely small. . The present invention will be explained below with reference to Examples.

Example 1 Sludge containing 200% by weight of WIS collected at a water treatment plant was added with 15.9% by weight of Denka CSA #20 (trade name) manufactured by Denki Kagaku Kogyo Co., Ltd. and 17% by weight of quicklime. Lime weight % and anhydrite 48. (containing % heel weight) was sufficiently mixed and dispersed to obtain an inner diameter of 16
The material was poured into a container with a depth of 15 cm and kept in a thermostatic chamber at 20°C to prevent water from evaporating, and the strength development at each age was determined according to the Proctor penetration resistance method specified in ASTM C4O3-65T. It was measured.

The results and blending conditions are shown in Table 1. Example 2 Table 2 shows the results of measuring the strength development of sludge with WIS of 10% saliva using the method of Example 1.

However, in this case, the sludge mixed and dispersed with CAS#20 will become lump-like, so divide it into 5 layers and pound with a ram with a cross section of 4 x 4 cm 30 times per layer.
It was packed in a predetermined container with a depth of 15 cm and a depth of 15 cm. Example 3 In Example 1, Nippon Cement (
Co., Ltd. product name: Asanojipcal (auin 4.9% by weight,
Table 3 shows the results using 33.1% by weight of quicklime and 46.4% by weight of anhydrite.

Comparative Example 1 In Example 1, Exp NO. Table 4 shows the results of mixing and dispersing in sludge at a ratio of 1.

Example 4 Next, instead of the sludge in Example 1, earth and sand contained in the crushed stone water flood used when making crushed stone was deposited in a settling tank.
Table 5 shows the results for the sludge from which the finest particles were collected.

Example 5 3Ca0●3A1203●CaF2 clinker obtained by melting and firing in an electric furnace was ground to a plain value of 4.500 ml, 1 part by weight, 5T
! A consolidation material was prepared by blending 1 part by weight of $L quicklime and 2 parts by weight of anhydrite.

When this was added at 1 volume% to WISl5O weight% sludge and mixed, 3 pieces solidified and the compressive strength in 1 day was 2K.
gIcT1 was prepared.

For comparison, a similar solidification process was carried out using a solidification material containing 7 parts by weight of ordinary Boltland cement instead of 1 part by weight of quicklime, but even after one day, It did not solidify.

In addition, when the hydrates of the consolidation materials were measured by X-ray diffraction, the formation of ettringite was observed in all cases.
Next, Table 6 shows the results of measuring the compressive strength after allowing the specimen to stand until a predetermined material age.

In the examples of the present invention, the strength increased as the material aged.

Claims (1)

[Claims] 1 3CaO・3Al_2O_3・CaSO_4 or 3
CaO・3Al_2O_3・CaF_23-50% by weight
, quicklime 5-35% by weight and calcium sulfate 30-70%
A solidification material for sludge containing % by weight.