JP2010076275A - Method for granulating cement mortar - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To granulate cement mortar which is separated from waste concrete, so as to impart hardness proper as a refilling-up material. <P>SOLUTION: The powdery cement mortar 2 is thrown in a freely rotatable rolling pan 1, water 3 is dripped on the cement mortar 2 and the rolling pan 1 is rotated to subject the cement mortar 2 to rolling granulation. The smooth granulation of the cement mortar 2 is performed by forming granulating nuclei by the dripped water and the cement mortar 2 can be granulated so as to have hardness proper as the refilling-up material. Further, the powdery cement mortar 2 is thrown in the freely rotatable rolling pan 1, and water 3 and quick lime are added to the cement mortar 2 to make the rolling pan 1 rotate to subject the cement mortar 2 to rolling granulation. By adding the quick lime, the quick lime acts as a granulation assisting material and the cement mortar 2 can be smoothly granulated to have hardness proper as the refilling-up material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for granulating cement mortar generated from waste concrete.

  Waste concrete, which occupies most of construction waste generated from demolished buildings, has been reused as roadbed material and backfill material. However, in recent years, the opportunity to reuse this waste concrete as an aggregate for concrete is increasing.

  When reused concrete is reused as aggregate for concrete, since various sizes of waste concrete are mixed, the concrete is finely crushed into a concrete block of a predetermined size in a processing factory or the like.

  Moreover, since the cement mortar adheres to the outer shell of the crushed concrete lump, it is necessary to remove the cement mortar from the concrete lump when reused as an aggregate. This is because when cement mortar adheres to the aggregate, it affects the quality of concrete cast using the aggregate.

  Various methods are used to separate cement mortar. For example, as shown in Patent Document 1, a concrete mass is brought into frictional contact with each other while applying a compressive force (hereinafter, this operation is referred to as grinding). There is something.

  In this apparatus, a cylindrical rotor is rotatably attached to an up-down direction eccentric rotation shaft provided in a casing, and an annular grinding chamber is formed between the casing inner wall and the cylindrical rotor.

An upper portion of the casing is provided with a charging portion, and the concrete lumps charged into the grinding chamber from the charging portion are brought into frictional contact with each other while being applied with a compressive force by the eccentric rotation of the cylindrical rotor. Cement mortar adhering to the surface of the material is separated from the concrete block.
Below the grinding chamber, the treated concrete block and cement mortar are dropped via a discharge restricting plate and transported to the next step. Thereafter, the concrete lump and the cement mortar are separated by a vibrating sieve or the like (for example, see Patent Document 1).

  The separated cement mortar is refined into powder by the above-mentioned grinding (hereinafter referred to as “fine state”), and in such a fine state, there is a problem that it is necessary to perform a scattering prevention process during transportation. In addition, if the backfilling process is performed in this fine state, the problem of excessive ground tightening may occur. If the ground is tightened too much, the water permeability is deteriorated, which may cause a problem of drainage treatment on the ground surface, and it is difficult to place a support pile or a pile for ground reinforcement.

Further, since the cement mortar is in a fine state, particularly when hexavalent chromium is contained, if it is backfilled as it is, a problem of elution of the hexavalent chromium may occur.
Therefore, granulation treatment of cement mortar in a fine state is performed by various methods.

As a general powder granulation process, for example, without using water or a binder, the powder is compressed with a pressure of a roll or the like to increase the cohesive force of the material and granulate, so-called compression granulation ( Dry granulation) and wet granulation using granulation using the adhesive force of water and binder.
In particular, when granulating the cement mortar, a technique (spray drying granulation) of granulating by adding kneaded water and kneading is used.

  In addition, as a processing method at the time of granulating various processed materials such as industrial waste, for example, the processed material is still subjected to solidification treatment by a cement solidification method, a plastic solidification method, etc. In the case of a mud or slurry, there is a technique of mixing the powdery waste and other powdered waste to granulate into a granular material (for example, see Patent Document 2). .

  Although it is not granulation of cement mortar, as a method of treating low water content purified water sludge, a water reducing material led by quick lime and a cement-based solidifying agent are added to the low water content purified water sludge, followed by stirring and kneading in a kneading mixer. In addition, there is a technique for granulating the processed product by adding and kneading a granulated powder material that leads quick lime. (For example, refer to Patent Document 3).

JP 2003-299773 A JP 54-71774 A JP 2006-88051 A

When granulating the cement mortar, particularly when the granulated product is used as a backfilling material, an appropriate hardness (easy to break) is required.
However, the spray-drying granulation involves kneading after spraying, so that the particles become too hard to achieve an appropriate hardness as a backfill material.

  The granulation methods of Patent Documents 2 and 3 are granulation methods for a mud-like or slurry-like processed product, and cannot be directly applied to granulation of cement mortar in a fine state.

  Therefore, an object of the present invention is to enable cement mortar separated from waste concrete to be granulated to an appropriate hardness as a backfill material.

In order to solve the above problems, the present invention drops water into cement mortar and rolls and granulates.
In this way, it has been found that the dripped water forms a granulation nucleus so that granulation is smoothly performed, and it can be granulated to an appropriate hardness as a backfill material.

As another means, water and quicklime were added to cement mortar, and rolling granulation was performed.
It has also been discovered that by adding quicklime, the quicklime acts as a granulation auxiliary material, allowing smooth granulation and granulation to an appropriate hardness as a backfill material.

  This invention employs rolling granulation as a granulation technique, and during the granulation, water dripping or addition of water and quick lime was performed, so cement mortar separated from waste concrete, It can be granulated to a suitable hardness as a backfill material.

  As an embodiment of the present invention, powder cement mortar is put into a rotatable rolling pan, water is dripped into the cement mortar, and the rolling pan is rotated to roll the cement mortar. The granulation method of the cement mortar to granulate is mentioned. In the granulation, quick lime can be added to the cement mortar.

  In addition, powdered cement mortar is put into a rotatable rolling pan, water and quicklime are added to the cement mortar, and the cement mortar is rolled and granulated by rotating the rolling pan. The granulation method of cement mortar is mentioned.

  That is, in the case of means involving the addition of quicklime, the method of adding water is not limited to dripping, and even if other methods such as spraying are adopted, the effect as a granulation auxiliary material by quicklime can be expected. However, if the addition method of water by dripping is employ | adopted in addition to addition of quicklime, the effect of the nucleus formation at the time of the said granulation can be anticipated collectively.

  Moreover, by adding quicklime, early drying after granulation becomes possible by the self-heating action of the quicklime. For this reason, the granulated product can be shipped early. At this time, it was confirmed that quick lime is preferably 5 to 20% by weight based on the cement mortar.

  In addition, when hexavalent chromium is contained in cement mortar, the hexavalent chromium can be rendered harmless by adding quick lime. For this reason, the problem of elution of hexavalent chromium can be avoided. It was confirmed that the hexavalent chromium detoxification effect was preferably 5 to 20% by weight based on the cement mortar.

The rolling pan may be configured to be rotatable with its center of rotation inclined with respect to the vertical direction. By setting the granulator to a pan tilt rotation type, granulation with a more appropriate hardness is possible for powdered cement mortar.
Moreover, in the bread tilt rotary granulator, the part (material contact part) that comes into contact with the processing material is a bread and a scraper or the like provided as necessary. However, the places where wear is likely to occur are limited. This facilitates maintenance of the granulator.

  Moreover, it was confirmed that the water added to the cement mortar is desirably 10 to 40% by weight with respect to the cement mortar. This is because when the water content is less than 10% by weight, no grains are formed or smooth granulation is not achieved, and when it exceeds 40% by weight, the cement mortar becomes mud.

  Examples of the present invention will be described below. As shown in FIG. 1, a rolling pan 1 composed of a flat bottom plate 1b that is circular in plan view and a peripheral wall 1c that rises around the bottom plate 1b is rotated by a driving force of a driving device 5 disposed below the rolling pan 1. Yes. The rotation center 1a is inclined with respect to the vertical direction.

  On the rolling pan 1, a plurality of nozzles 4 a having a function of dropping water (water droplets) 3 is provided. Water is supplied to each nozzle 4 a through the pipe 4.

  The powdered cement mortar 2 is put into the rolling pan 1, and the rolling pan 1 is rotated as shown by the arrow A while dripping water 3 from the nozzle 4a into the cement mortar 2 (see arrow C). And granulate. The cement mortar 2 is granulated to a predetermined particle size while flowing in the rolling pan 1 as indicated by an arrow B.

Hereinafter, Table 1 shows a blending example when the cement mortar 2 is granulated, and the result of the granulation.
In Experiments 3 to 14, a plurality of granulation tests were performed with different amounts of water added. Regarding the addition of water, the water addition method was sprayed only in Experiment 13, and water was added dropwise otherwise. In Experiments 1 and 2, no water was added.
In Experiments 6-8 and 10-14, a plurality of granulation tests were performed with different amounts of quicklime added. Regarding the addition of quicklime, in experiments 1 to 5 and 9, quicklime was not added, and when quicklime was not added, the same amount of cement was added (experiments 3 to 5 and 9).

  After the test, a hexavalent chromium elution test was performed on each of Experiments 4, 6, 7, 8, 10 and Experiments 1 and 2 in which granulation was not performed.

  In the granulation evaluation in the table, ◯ indicates that the granulation is properly performed, Δ indicates that the granulation is partially properly performed, and × indicates that the granulation is not properly performed.

  In addition, in the judgments in the table, ◯ indicates that the elution of hexavalent chromium was less than the specified amount (“soil environmental standard value 0.05 mg / l” shown in the margin of Table 1), and ◎ indicates particularly low elution amount. And x indicate that the elution amount was not less than the specified amount.

From the above results, as far as the addition amount of water 3 is concerned, it is understood that when the addition method by dropping is adopted, it is preferably 5 to 40% by weight with respect to cement mortar 2 (granulation evaluation in the table ○ Mark and △ mark). In addition, if the dripping amount of the water 3 was 10 to 40 weight%, it has confirmed that a granulation condition was especially preferable (refer granulation evaluation (circle) mark in a table | surface). It has also been confirmed that when the amount of water 3 dropped is lower than the value of Experiment 11 (less than 5% by weight), granulation is not successfully performed.
Furthermore, when the addition of water 3 was sprayed without depending on dropping, no granulation was achieved even when 10 wt% of water 3 was added as in Experiment 13.

In addition, as far as the amount of quicklime added is concerned, it is found that it is preferably 3 to 20% by weight with respect to cement mortar 2 when dripping 5% by weight or more of water 3 (granulation evaluation ○ mark in the table) And △ mark). In addition, at this time, if the addition amount of quicklime was 5 weight% or more, it has confirmed that the granulation condition was especially preferable (refer granulation evaluation (circle) mark in a table | surface).
On the other hand, when the amount of quicklime added is less than 5% by weight, as shown in Experiment 14, the granulation state is slightly inferior. In addition, although the addition amount of quicklime can also be 20 weight% or more, it does not change in the effect.

However, as in Experiment 11 and Experiment 12, when the amount of water 3 dropped is 5% by weight or 30% by weight, even if the amount of quicklime added is 5% by weight or more, the result of the granulation state is somewhat inferior. ing.
In this regard, in Experiment 10 in which the amount of water 3 was dropped from 10 to 15% by weight, Experiment 6 in which the amount of water dropped was 20% by weight, and Experiment 8 in which the amount of water dropped was 25% by weight, Good granulation results have been obtained under conditions where the addition amount is 7% by weight, 20% by weight, and 5% by weight. Moreover, if the addition amount of quicklime is 10 weight% or more like experiment 7, the favorable granulation result is obtained even if the dripping amount of water 3 is 30 weight%.

  Regarding the elution of hexavalent chromium, Experiment 10 in which the amount of quicklime added was 7% by weight, Experiment 7 in which 10% by weight was added, and Experiment 6 in which 20% by weight was added gave particularly good results.

Perspective view showing the whole granulator

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rolling pan 1a Rotation center 1b Bottom plate 1c Perimeter wall 2 Cement mortar 3 Water 4 Piping 4a Nozzle 5 Drive device

Claims (6)

  By putting powdered cement mortar (2) into the rotatable rolling pan (1), dropping water (3) into the cement mortar (2), and rotating the rolling pan (1). The granulation method of the cement mortar which rolls and granulates the said cement mortar (2).   The granulation method of the cement mortar according to claim 1, wherein quick lime is added to the cement mortar (2).   Powdered cement mortar (2) is put into a rotatable rolling pan (1), water (3) and quicklime are added to the cement mortar (2), and the rolling pan (1) is rotated. A method for granulating the cement mortar, in which the cement mortar (2) is rolled and granulated.   The said quicklime is 5 to 20 weight% with respect to the said cement mortar (2), The granulation method of the cement mortar of Claim 2 or 3 characterized by the above-mentioned.   The cement mortar according to any one of claims 1 to 4, wherein the rolling pan (1) is rotatable in a state in which a rotation center (1a) is inclined with respect to a vertical direction. Granulation method.   The granulation method of cement mortar according to any one of claims 1 to 5, wherein the water (3) is 10 to 40% by weight based on the cement mortar (2).

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