JPH10263313A - Regeneration of cleaning water for aggregate for concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To regenerate a cleaning water which gives no influence on the slump flow even when a flocculant deposits on crushed sand by subjecting a contaminated water produced in a cleaning process of an aggregate for a concrete to a treatment with carboxymethylcellulose and polyaluminum chloride so as to flocculate and precipitate the sludge, and then adding a cellulase to the supernatant. SOLUTION: A carboxymethylcellulose(CMC) is added to a contaminated water produced in a cleaning process of a crushed sand and the like so that the suspended substance which intrinsically has negative charges is further electrified into negative changes by the anionic property of the CMC. Then polyaluminum chloride(PAC) having positive charges is added to neutralize the charges so that even inorg. fine particles which can no be precipitated by the weak negative charges intrinsic to the inorg. suspended substance can be rapidly precipitated to clarify the contaminated water. When the recovered water contains CMC and PAC as the flocculant after the precipitate is separated, the flocculant affects the slump flow, therefore, a cellulase is added to decompose CMC. Thus, the regenerated cleaning water can be used to produced a good concrete.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for producing fine aggregate used as an aggregate for concrete, in which crushed sand obtained by appropriately crushing rough stones such as mountain gravel, sea gravel, land gravel and crushed stone is washed with water. Then, it is manufactured in a process of taking out crushed hydrous sand containing water.

[0002] The present invention relates to a treatment method for regenerating and reusing sludge water generated at this time without affecting the properties of concrete.

[0003]

2. Description of the Related Art Sludge water generated when washing crushed sand or the like is generally recovered and reused after a polyacrylamide-based polymer flocculant is added to coagulate, precipitate, and separate the slurry. If the polymer flocculant remains in the recovered water, it will be taken into the hydrated crushed sand washed with this, causing a problem that slump does not appear during concrete production in a ready-mixed plant.

In the present invention, carboxymethylcellulose (hereinafter referred to as CM) is used instead of a polyacrylamide-based polymer flocculant.
C) and polyaluminum chloride (hereinafter abbreviated as PAC) to treat the sludge water, and then wash the crushed sand with the recovered water to which cellulase has been added. The present invention also provides a method for treating recovered water that does not affect the properties of concrete.

[0005]

When the polyacrylamide polymer flocculant is mixed with concrete while adhering to the crushed sand, the polymer flocculant becomes 30 ppm relative to the mixing water.
It is known that the above concentration affects the slump flow of concrete. The standard amount of the polymer coagulant used is about 1 to 4 ppm based on the sludge water (assuming that the surface water is 5%, and 0.5 to 1.0 ppm based on the kneading water), and there is no problem in the usual use method.

However, the dissolution concentration of the polymer flocculant is generally adjusted to 1,000 ppm, and the solution is added to a chute in which sludge water flows. It is hard to say that the amount of the solution added is very strictly controlled in a state controlled by the valve opening.

Further, since the recovered water is circulated, the polymer flocculant is accumulated in the supernatant water, and there is a concern that the polymer flocculant may be concentrated by evaporation of water in the washed crushed sand yard. During long working periods, there is a great concern that it will be included in the danger area.

An object of the present invention is to provide a method for regenerating fine aggregate washing water which does not affect the slump flow of concrete even if a flocculant adheres to crushed sand.

[0009]

Means for Solving the Problems The present inventors have conducted a coagulation and sedimentation method using a combination of CMC and PAC (Japanese Patent Publication No. 55-33672), which is known as a method for clarifying polluted water in construction work, when washing the crushed sand. The cellulase was added to the supernatant obtained by the CMC-PAC coagulation sedimentation method as a result of a detailed study of the effects of CMC and PAC mixed in the fine aggregate, applied to the polluted water generated in the above. As a result, they found that even if CMC and PAC used as coagulants were mixed into concrete, the slump flow of concrete was not affected, and the present invention was reached.

That is, according to the method of the present invention, the polluted water generated when the concrete aggregate is washed is first treated with CMC and PMC.
AC treatment, and then cellulase is added to the supernatant obtained by coagulating and sedimenting the sludge.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a method for regenerating washing water to obtain good fine aggregate that does not affect the slump flow of concrete when clarifying and reusing polluted water obtained by washing crushed sand and the like. However, it is a method that can also be used to recover washing water from mixers and agitator trucks that are generated daily in concrete plants, and the contaminated water treated by this method is sufficient as reclaimed water and mixed water for concrete. It can be used.

The CMC used in the first step of the present invention is used as a dispersant and a stabilizer for clay minerals in the fields of ceramics and gypsum board, and is used to stabilize bentonite slurry in drilling mud for oil drilling and in a stable liquid method for construction work. And is widely used to maintain its fluidity. As described above, CMC is generally used as a dispersant and a stabilizer in water, and when the target suspended particles are neutrally or negatively charged, the effect as a flocculant has almost no effect. , Ag, Cu, Pb, Zn, Al, Fe, etc., have the property of forming and precipitating an insoluble metal salt of CMC corresponding to the ion.

PAC is formally referred to as basic aluminum chloride, but the one generally used as a flocculant is 4AlCl ₃ .2Al (OH) ₃ , 3A
lCl ₃ .3Al (OH) ₃ , 2ALCl ₃ .4Al
It is a mixture of (OH) ₃ , AlCl ₃ .5Al (OH) ₃ , and is generally used as a commercial product having a low viscosity and to which some salts or the like are added in order to enhance the coagulation effect. This PAC hydrates in water to become a polymer of aluminum hydroxide and is strongly positively charged.

The cellulase added in the second step of the present invention is an enzyme that hydrolyzes cellulose, and has recently reached the stage of industrial production and full practical use.

In order to select a cellulase having an effect on the present invention from commercially available cellulases, a 1% aqueous solution of CMC is prepared, and 0.5 to 1.0 ppm of cellulase is added to the solution, and the solution is stirred and allowed to stand. It is possible by a method of measuring a change in viscosity of the liquid. When the viscosity of the 1% aqueous solution is about 500 cps, the viscosity becomes 1/2 to 1/3 of the original viscosity 3 hours after the addition of the cellulase, and decreases to about 1/10 after one day.

The type and amount of the cellulase are not particularly limited, but those having a large effect of decreasing the viscosity in a short time by addition of a small amount are preferred.

In the first step of the present invention, when CMC is added to polluted water generated when crushed sand or the like is washed, CMC is added.
Is absorbed by polluted soil particles to form protective colloid, and CMC
The negative charge of the inorganic suspension material is negatively charged more strongly by the anionic property of the inorganic suspension. Next, the charge is neutralized by adding a PAC having a positive charge, and a precipitate is rapidly formed to inorganic fine particles that were not precipitated by the weak negative charge of the inorganic suspended substance, thereby clarifying the polluted water. Will be.

If CMC or PAC used as a flocculant remains in the recovered water after separating this precipitate, the slump flow is affected, though much weaker than a polyacrylamide-based polymer flocculant. By adding cellulase and decomposing CMC, it is possible to obtain washed fine aggregate that does not affect the properties of concrete.

[0019]

The concrete using fine aggregate using the washing water regenerated by the method of the present invention has no influence on the slump flow at the time of concrete production as compared with the one using a polyacrylamide polymer flocculant. It can provide high quality concrete.

[0020]

The present invention will now be described in more detail by way of examples with reference to a mortar test.

1) Mortar test 1-1) Preparation of mortar According to the composition shown in Table 1 in a JIS mortar mixer, 1/2 amount of fine aggregate used, セ メ ン ト amount of cement and fine aggregate, aggregating agent, etc. A
E The water reducing agent and water were sequentially added and mixed five times with a stirring blade, followed by kneading for 180 seconds to prepare.

[0022]

[Table 1]

1-2) Materials used Cement: Ordinary Portland cement (Asano, Mitsubishi, Chichibu Onoda Cement products are mixed in equal amounts, specific gravity = 3.16) Fine aggregate: Kimitsu land sand (5 mm on cut, specific gravity = 2.61, Coarse particle ratio = 2.48) AE water reducing agent: Lignin sulfonic acid type AE water reducing agent (trade name: Sanflow K, manufactured by Nippon Paper Co., Ltd.) Flocculant: polyacrylamide type flocculant (trade name: Konan Floc ZH880H, manufactured by Konan Chemical Co., Ltd.) Polyacrylamide-based flocculant (trade name: Koyo Floc P802, manufactured by Koyo Chemical Co., Ltd.) Inorganic flocculant (trade name: PAC # 100L, manufactured by Asada Chemical Industry Co., Ltd.) CMC: Sunrose SN50C-P, trade name; : Product name Cellulase A "Amano" 3, manufactured by Amano Pharmaceutical Company name Cellsoft L, manufactured by Novo Nordisk Bio-Industry

1-3) Test method The mortar slump was measured using a mini slump cone (iron having an upper inner diameter of 5 cm, a lower inner diameter of 10 cm, and a height of 15 cm) according to JIS A1101. Further, the spread of the mortar at that time was measured at two points, a direction in which the diameter was recognized as the maximum and a direction perpendicular to the direction, and the result was defined as a slump flow. The air volume is ASTM
It was measured according to C185.

The CMC decomposing effect of cellulase was determined by preparing a 1% aqueous solution of CMC, adding 1.0 ppm of cellulase, and measuring the solution viscosity at 25.0 ° C. using a B-type rotary viscometer.

2) Test results 2-1) Influence of polymer flocculant on slump After half of the fine aggregate and cement shown in Table 1 were put into the mixer, the remaining fine aggregate was added to the polyacrylamide-based high aggregate. After a predetermined concentration of a molecular coagulant was added and mixed with a 0.1% solution, water in which an AE water reducing agent was dissolved was added to prepare a mortar. Table 2 shows the results.
Are shown in Comparative Examples 2 to 7. It can be seen that the polyacrylamide polymer flocculant affects slump and slump flow at a concentration of 10 ppm with respect to the kneading water.

2-2) Effect of PAC on slump In the same manner as in the previous section, a 1.0% solution of PAC was added and mixed at a predetermined concentration in place of the polyacrylamide polymer flocculant to prepare a mortar. The results are shown in Comparative Examples 8 to 10 in Table 2. It can be seen that PAC does not significantly affect the slump even when it is added to the kneading water at a concentration of 100 to 1,000 ppm.

2-3) Influence of CMC on slump In the same manner as in the previous section, a mortar was prepared by adding a 0.1% solution of CMC at a predetermined concentration and mixing instead of PAC. The results are shown in Comparative Examples 11 to 16 in Table 2. It can be seen that the addition of CMC to the kneading water at a concentration of 100 ppm or more affects slump and slump flow.

2-4) CMC · P containing cellulase
Influence of AC System on Slump As in the previous section, a mortar was prepared by mixing a predetermined concentration of a 0.1% solution of CMC and a 1.0% solution of PAC, adding 1.0 ppm of cellulase to a mixture left for 1 hour, and mixing. The results are shown in Examples 1 to 4. It can be seen that the fine aggregate obtained by the method for recovering washing water of the present invention does not affect the slump and the slump flow even if the flocculant adheres and is mixed during the production of concrete.

2-5) Change in viscosity of CMC solution by cellulase Table 3 shows the results obtained by adding 1.0 ppm of two types of cellulase to a 1% aqueous solution of CMC and measuring the viscosity of the solution over time. All cellulases degrade CMC well.

[0031]

[Table 2]

[0032]

[Table 3]

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masakuni Kudo 1551 Higashidaira, Higashimatsuyama-shi, Saitama Prefecture Nippon Paper Industries Co., Ltd.

Claims (1)

[Claims] 1. To reuse polluted water generated when washing aggregate for concrete, the polluted water is first treated with carboxymethylcellulose and polyaluminum chloride, and then treated by adding cellulase to the supernatant water. A method for regenerating aggregate washing water for concrete, comprising: