JP5043424B2 - Method for treating hardened cement and processed material - Google Patents

Description

  The present invention relates to a method for treating a hardened cement body and a pre-processed product in which the hardened cement body is treated by safe and simple means.

  There is no doubt that hardened cement, such as concrete, mortar, and slate, has a history of about 100 years and is one of the main materials that have supported the cultural society of the 20th century. It has become an integral part of our lives.

  This is because the hardened cement materials such as cement, gravel, sand, asbestos, water, etc. are inexpensive and easy to obtain in large quantities, and the properties such as good moldability are suitable for building structures. In addition, the hardened cement body has an advantage that it becomes a building material excellent in earthquake resistance, fire resistance, and sound insulation by being integrated with a reinforcing bar or a steel frame.

  Due to the advantages of such hardened cement bodies, hardened cement bodies can be used in various fields such as building structures, utility poles, road paving stones, concrete block fences, railroad sleepers, tunnels, dams, bridges, revetments, etc. In the future, it will be easily expected that it will be used in a large amount in a wide range of fields as an important material in the 21st century.

  However, once the cement hardened body has finished its role and becomes waste, various problems occur in order to treat this waste.

  In other words, since it is difficult to incinerate the hardened cement, it is currently disposed of by landfill or the like after being crushed, but in order to crush a relatively high strength hardened cement, In addition to requiring energy, dust generated during the crushing operation may cause diseases such as pneumoconiosis to the worker.

  In addition, because of its stability, the hardened cement body is difficult to undergo biodegradation. For this reason, the hardened cement body that has been disposed of in landfills will remain in the environment semipermanently without being decomposed in the soil. Alkaline components that flow out of the hardened body, combined with the stability of the cemented hardened body, hinders the growth of animals and plants over a long period of time, so that the habitat of animals and plants in urban areas, landfills, waste disposal sites, etc. The problem is that the number is drastically reduced.

  In particular, among hardened cementitious bodies, slate has a history of blending asbestos, which is harmful to the human body, for many years. The occurrence of serious health damage such as mesothelioma and lung cancer due to the contamination of workers is a very large social problem.

  Therefore, recently, in order to solve the above problems, various studies have been conducted on a method for treating slate waste materials containing asbestos (for example, Patent Document 1).

JP 2005-279589 A

  The method for treating a slate waste material described in Patent Document 1 described above includes a slate containing a slate waste material containing asbestos without crushing slate waste, a mixture of boric acid and sodium carbonate, or a mixture of borax and sodium carbonate. After pretreatment by impregnating the voids inside the slate from the surface of the waste material, the pretreated slate waste material is immersed in a melting furnace filled with a dissolving agent and heated to a range of 780 ° C. to 1000 ° C. The asbestos contained in the slate waste is melted and vitrified. In order to sufficiently impregnate the dissolving agent in the voids in the slate in the pretreatment, the slate is used under reduced pressure or pressure. Inevitably, it is necessary to immerse the waste material in a solubilizing agent, or immerse it in the solubilizing agent after generating microcracks in and on the surface of the slate waste material. The equipment is as large-scale, there is a problem such as increase processing costs.

  Therefore, as a result of intensive investigations to solve such problems, the present inventor performed the method for treating a hardened cement according to the present invention, characterized in that the hardened cement is treated with an acidic solution and then crushed. It has been completed.

  That is, the present inventor pays attention to the fact that the hardened cement has a very weak property against acid, and if the hardened cement is treated with an acidic solution before crushing operation, the hardened cement is remarkably weakened. From this, it was found that the crushing operation can be performed with less energy.

  In addition, the cement hardened body after being treated with an acidic solution is in a state where the surface is coated with a viscous solution, so that the scattering of dust is remarkably reduced during the crushing operation, and the working environment is in a good state. They also learned that they can be maintained at the same time.

  Furthermore, the present inventor coated the glass hardened body after crushing with a glass film by applying water glass, and then heat-treated to harden the cement containing asbestos such as asbestos-containing slate. Even the body gained the knowledge that asbestos can be made harmless and can be safely processed.

  And the already processed thing processed by the processing method of the cement hardening body of the present invention does not have a restriction in the place for landfilling, and can be used as a building material again as a cement raw material or an aggregate. This knowledge was also obtained.

  The present invention has been completed on the basis of the above knowledge, and can treat a hardened cement by a safe and simple operation. Even a hardened cement containing asbestos can be made harmless and safe. It aims at providing the processing method of a new hardened cement body which can be disposed of or used for recycling, and a processed product.

The processing method of the hardened cement body of the present invention, which is a means for solving the above problems, is to treat the hardened cement body with an acidic solution, then crush it, and apply the coating water glass to the ground hardened cement body. The hardened cement body after the crushing is coated with a glass film, and then heat-treated .
Hereinafter, a method for treating a cured cement body of the present invention (hereinafter referred to as “method of the present invention”) and an already-treated product will be described in detail.

  “Cemented hardened body” to which the method of the present invention is applied refers to a product obtained by mixing at least cement and water, and drying and hardening this to a desired shape, and further, aggregate, fiber, admixture, etc. Can be appropriately blended.

  Specific examples of hardened cement are mortar, concrete, slate, etc., mainly building materials for building roofing materials, wall materials, exterior materials or interior materials, utility poles, road paving stones, concrete block fences, railway tracks. Examples include sleepers, tunnels, dams, bridges, and revetments.

  In the method of the present invention, first, these hardened cement bodies are treated with an acidic solution.

  Here, in the method of the present invention, “treating with an acidic solution” means that the hardened cement body and the acidic solution are brought into contact. More specifically, the acidic solution is applied to and spread on the hardened cement body. This means that the hardened cement body is immersed in an acidic solution. In general, a treatment means by dipping that can increase the contact time between the hardened cement body and the acidic solution is preferably used.

  In the method of the present invention, the treatment time when treating with an acidic solution is usually that if the treatment time is consumed for a longer time, the hardened cement body becomes proportionally brittle. The treatment time may be determined over several hours from several minutes to about 10 hours to several hours or several days depending on the penetrating power to the hardened cement, the processing means, and the crushing ability in the crushing operation, and is particularly limited. It is not a thing.

  In the present invention, since the hardened cement body is treated with an acidic solution, the alkali component that maintains the strength of the hardened cement body is neutralized, and the hardened cement body can be significantly weakened. The crushing work can be done with energy.

  In addition, the hardened cement after treatment with an acidic solution is in a state where the surface is coated with a viscous solution, so that dust scattering during the crushing operation is significantly reduced, and the working environment is maintained in a good state. It can be done.

  The “acidic solution” used in the method of the present invention is not particularly limited as long as it has an acidity that can neutralize the alkali component that maintains the strength of the cement cured body. For example, sulfuric acid, Aqueous solutions containing inorganic acids such as hydrochloric acid and nitric acid as acid components, polyoxymonocarboxylic acid, citric acid, glycolic acid, malic acid, gluconic acid, lactic acid, formic acid, acetic acid, propionic acid, butyric acid, tartaric acid, oxalic acid and succinic acid At least one or more selected from known acidic solutions such as aqueous solutions containing an organic acid having a carboxyl group (—COOH) such as an acid as the acid component can be suitably used, but the effect on work safety and the environment In view of the above, it is particularly preferable to use an organic acid as the acid component.

  Here, the blending amount of the acid component in the acidic solution is appropriately determined depending on the type of the cement cured body to be treated and the type of the acidic solution, and is not particularly limited. Is preferably about 15 to 80% by weight, more preferably about 15 to 60% by weight, based on the entire acidic solution.

  If the blending amount of the acid component is less than 15% by weight with respect to the whole acidic solution, the treatment time for reducing the strength of the hardened cement is undesirably long. On the other hand, the blending amount is 80% by weight with respect to the entire acidic solution. If it exceeds%, an effect of a certain level or more cannot be obtained, which is not preferable from the viewpoint of economy.

  In the method of the present invention, it is preferable to add a surfactant to the acidic solution in order to improve the permeability of the acidic solution to the cement hardened body. The “surfactant” is an anionic interface. Any of an active agent, a cationic surfactant, a nonionic surfactant, an amphoteric surfactant and a nonionic surfactant can be used.

  Specifically, as the “anionic surfactant”, fatty acid salt type, alkylbenzene sulfonate type, alkyl sulfate ester type, linear secondary sulfonate type, dialkyl sulfosuccinate type, POE alkyl or Examples thereof include alkylphenyl ether sulfate salt type, POE alkyl or alkylphenyl ether phosphate salt type, etc. Examples of the “cationic surfactant” include alkyl picolinium chloride type, alkyltriethylammonium chloride type and others. And quaternary ammonium salt type.

  Examples of the “nonionic surfactant” include POE alkylphenyl ether type nonion, POE alkyl ether type nonion, POE polyoxypropylene block polymer type nonion, POE glycol alkyl ester type nonion, sorbitan fatty acid ester type nonion, and sucrose fatty acid. Examples include ester type nonions.

  Furthermore, examples of the “amphoteric surfactant” include an alkylcarboxybetaine type, an alkylaminocarboxylic acid type, and an alkylimidazoline type.

  In addition, examples of the “nonionic surfactant” include POE alkyl ether, POE alkyl phenyl ether, sucrose fatty acid ester, ethylene glycol and glycerin.

  The amount of these surfactants to be added to the acidic solution is appropriately determined depending on the type of the hardened cement cement, the type of the acidic solution, and the like, and is not particularly limited. Is preferably about 5 to 60% by weight, more preferably about 5 to 40% by weight, based on the entire acidic solution.

  If the addition amount of the surfactant is less than 5% by weight with respect to the whole acidic solution, it is not preferable because the penetrating power to the hardened cement cannot be sufficiently improved. On the other hand, the addition amount is 60% with respect to the whole acidic solution. If it exceeds 50%, it is not preferable because a further effect cannot be obtained and the relative proportion of the acid component decreases.

  In addition, you may add these surfactants in mixture of not only one type but 2 or more types.

  Next, in the method of the present invention, the cement hardened body weakened by the treatment with the acidic solution is crushed. However, the crushing method is not particularly limited, and a hammer, a power shovel, or a crusher is used. Crushing by physical means such as human power using a mill or roller or a crusher is common.

  In addition, the degree of crushing may be appropriately dealt with depending on the subsequent disposal situation, and is not particularly limited. However, in view of the fact that acceptance as a cement raw material is within 3 cm square, after crushing It is preferable that the cement hardened body is crushed so as to be within 3 cm square, particularly preferably within 1 cm square.

  Here, for a relatively thick cement cured body, it takes a long time to sufficiently reach the acidic solution until reaching the inner deep layer, or only with the treatment and crushing work with the acidic solution in one step. In some cases, it becomes difficult to finely grind the hardened cement body.

  In this case, if the hardened cement body that has been primarily crushed to a certain size is treated again with an acidic solution, it can be brought into contact with the acidic solution up to the deeper inner layer of the hardened cement body. It is preferable to repeat the treatment with an acidic solution and the crushing operation.

  By the way, among the cement hardened bodies, there are some which contain asbestos harmful to the human body, such as an extruded cement board, a residential roof slate, a fiber reinforced cement board, a siding board, and an asbestos cement cylinder.

  This asbestos is a convergent body of fine fibers having a fiber diameter of 0.1 μm or less, and has a needle-like shape with sharp tips of individual fibers. Needle-like particles (asbestos dust) have the property of being easily sucked into the human body together with exhaled air.

  The asbestos dust once sucked into the human body remains stuck in the lung mucosa and esophageal mucosa, and remains in the body for a long time without being corroded because it is a mineral fiber. Therefore, it has been confirmed that asbestos dust remaining in the body is a causative substance that causes mesothelioma and cancer in the digestive and respiratory organs.

  As described above, according to the method of the present invention, dust scattering during the crushing operation is extremely small. However, when processing hardened cement containing very toxic asbestos, the safety of the workplace is ensured. It may be difficult to do.

  To deal with this problem, it is conceivable to carry out the crushing operation in a closed crusher, but this increases the cost of equipment investment.

Therefore, in the present invention, in an acidic solution, it is preferable to further add a for water glass prevents dust scattering.

That is, the acidic if the solution added to a water glass prevents dust scattering in the acidic solution dust scattering prevention water glass enters the body cement with, asbestos is water glass for preventing scattering of dust particles contained within the cement hardened body As a result, it is possible to prevent asbestos from being scattered as much as possible during the subsequent crushing operation.

As the "dust-preventive water glass", dissolved in the acidic solution has a degree of fluidity that can penetrate the gaps of the cement hardened body, and, after penetration as long as it cured as glass coat The present invention is not particularly limited, and in the present invention, an aqueous solution mainly containing at least one selected from metal silicates such as lithium silicate, sodium silicate, potassium silicate, and calcium silicate is generally used. Is preferably used.

Further, the addition amount relative to the acid solution for water glass dedusting may be suitably determined depending on, for example in an acidic solution and the type of dust prevention water glass used, it is not particularly limited, generally Is preferably about 5 to 65% by weight, more preferably about 30 to 50% by weight, based on the entire acidic solution.

In less than 5 wt% amount for water glass dust prevention for the entire acidic solution, unfavorably the case that it can not be sufficiently suppressed scattering of asbestos in the crushing operation, whereas, the amount of added acidic solution If it exceeds 65% by weight with respect to the whole, it is not preferable because an effect beyond that cannot be obtained, and the permeability of the acidic solution to the hardened cement body may deteriorate.

  And, since the alkaline component is neutralized by the acid component, the already-treated product of the present invention after the execution of the method of the present invention, that is, the crushed cement hardened body, can be landfilled at an appropriate place. It can also be recycled as a cement raw material.

  However, in the hardened cement body containing asbestos, asbestos may still be exposed even after the method of the present invention is performed, so that asbestos may be exposed again.

  Here, of the asbestos, for example, chrysotile is known to desorb crystal water at about 700 ° C. when heated, and to be denatured into harmless forestlite at about 900 ° C. Therefore, the method of the present invention contains asbestos. A means for detoxifying asbestos by adding heat treatment to the already-treated product obtained by treating the hardened cement body to be used is also conceivable.

  However, in order to completely detoxify the asbestos contained in the cement in the combustion furnace, a high temperature furnace of 1400 to 1500 ° C. is actually required, and a normal combustion furnace can withstand such a high temperature. There is a problem that can not be.

Therefore, in the method of the present invention, in order to detoxify the asbestos, in particular, with respect to the cement hardened body of crushed, the cement hardened body after the crushed coated with a glass film by applying a coating waterglass Then, it is preferable to perform heat treatment.

  In other words, when a cemented hardened body coated with a glass coating is fired in a furnace, first, with about 700 ° C. heat, crystal water is released from the asbestos in the hardened cemented body, resulting in powdered asbestos that has lost its binding power. Furthermore, when the glass coating begins to melt at a temperature exceeding 800 ° C., the asbestos that has lost its cohesive strength can be firmly bonded to the molten glass in powder form, and a detoxified solid can be obtained. Thus, asbestos can be sufficiently detoxified even if a relatively low temperature furnace of about 800 to 1000 ° C. is used.

  The detoxified solid matter is not limited in the place for landfill, and can be used as a building material again as a cement raw material or an aggregate.

Here, as "coating water glass" is used, it is possible to use suitably the same as the dust-preventing water glass to be added to the above acidic solution, to avoid repetition, the description thereof is omitted here.

Note that this coating water glass is cured by drying it is, time is relatively long required for the curing, also coating water glass cured in such a state, water resistance and heat resistance insufficient because it may become many, yet also be weakened by reacting with carbon dioxide, in the method of the present invention, it is preferable to use a curing agent together with the coating water glass.

As the "curing agent", by being added to the coating for water glass, as long as it promotes the curing of the coating water glass it is not particularly limited, suitably using known curing agent Specifically, for example, organic carboxylic acids such as formic acid, acetic acid and propionic acid, organic sulfonic acids such as benzenesulfonic acid and toluenesulfonic acid, esters such as methyl formate, methyl acetate and ethyl acetate, formaldehyde Aldehydes such as acetaldehyde, glyoxal, hydrochloric acid, sulfuric acid, nitric acid, boric acid, chloric acid, metaphosphoric acid, pyrophosphoric acid, polyphosphoric acid, hypophosphorous acid, phosphorous acid, superphosphoric acid, potassium hypophosphite, Inorganic acids such as potassium phosphite and its salts, zinc oxide, calcium oxide, magnesium oxide, lead oxide, oxidation Oxides of Taka metals such as aluminum, silicides such as calcium silicate, sodium silicofluoride, may be mentioned at least one or more species selected from silicofluoride such as potassium fluorosilicate.

Among them, in the method of the present invention, a hardened cement body from performing heat treatment after coating with glass coating, an organic-based curing agents, particularly preferable to use an inorganic hardening agent, also coating waterglass type curing agent dispersed in the order that may interfere with the permeability of the coating water glass, they are preferable to use those having a hydrophilic property capable rice soluble in water as a solvent.

Then, in the method of the present invention, with respect to such cement hardened body after crushing, by applying the coating water glass, cured with infiltrate coating water glass in the gap between the hardened cement, with hardened cement paste The surface of asbestos existing inside is coated with a glass film.

Here, as the means for applying the coating water glass relative to the cement hardened body after crushing it is not particularly limited, for example, immersion of the cement hardened body of the coating waterglass in accordance brushing Examples of the application include spraying and spraying or nozzle type spraying. From the viewpoint of workability, spraying or nozzle type spraying is preferable.

  Further, the coating step is not limited to one time, and it is preferable to perform the coating twice or more because a stronger glass film can be formed by a plurality of times of coating.

Furthermore, the coating amount of the coating water glass, they are sufficient if a very thin film is formed on the surface of the crushed hardened cement paste, not particularly limited, the coating amount of the coating waterglass The larger the amount, the stronger the glass film can be formed. Generally, however, a coating of about 50 to 600 g is applied to 1 m ² of the crushed cement hardened body in a state of being spread in a plane. it is preferred to use water glass is to be applied.

  Next, in the method of the present invention, the cement cured body after crushing coated with a glass coating is subjected to heat treatment. As described above, the cement cured body after crushing coated with a glass coating is 800- Even if a relatively low temperature furnace of about 1000 ° C. is used, asbestos can be sufficiently detoxified.

  Therefore, in the method of the present invention, the heat treatment can be performed at a relatively low temperature of about 800 to 1000 ° C., and energy saving in the heat treatment can be realized.

  Moreover, since the asbestos dust does not scatter during the heat treatment, the worker can work safely without sucking the asbestos dust.

  In the method of the present invention, when the hardened cement body after crushing is coated with a glass film and subjected to heat treatment, the hardened cement body after crushing is sufficient so that the coating with the glass film is sufficient. Crushing is preferably performed so as to be within 10 mm square, and particularly preferably within 5 mm square.

  And since the processed material of the present invention processed by the method of the present invention is disposed of in a detoxified state by heat treatment or disposed of in landfill, there is no possibility of causing secondary contamination, and dumping, landfilling There is no limit to the location for this purpose.

  In addition, the processed material of the present invention rendered harmless by heating can be reused as building materials such as cement materials and aggregates.

  The present invention has the above-described configuration, and can process a hardened cement body in a safe and simple operation, and even a hardened cement body containing asbestos can detoxify asbestos and safely process the cement. It is the processing method of a hardening body, and a processed thing.

  That is, according to the method of the present invention, the hardened cement body is treated with an acidic solution before the crushing operation. Therefore, the hardened cement body can be remarkably weakened, and the crushing operation can be performed with less energy. .

  In addition, the cement hardened body after being treated with an acidic solution is in a state where the surface is coated with a viscous solution, so that the scattering of dust is remarkably reduced during the crushing operation, and the working environment is in a good state. Can be maintained.

Furthermore, with respect to the cement hardened body after the crushing, the coating water glass coated with a glass film by coating, and then, if Hodokose heat treatment, using a relatively low temperature furnace at about 800 to 1000 ° C. However, asbestos can be sufficiently detoxified, and thus energy saving in the heat treatment can be realized.

  And the processed material of the present invention that has been rendered harmless by the method of the present invention is not limited in the place for landfilling, and can be used as a building material again as a cement material or an aggregate. .

  Examples of the method of the present invention will be described below, but the method of the present invention is not limited to these examples.

<Preparation of acidic solution>
Citric acid crystal particles and water were mixed at a weight ratio of 1: 1 to obtain an acidic solution (pH 0.9).

<Cemented body>
Mortar was prepared as a cement hardened body.

  When mortar as a hardened cement body is immersed in the acidic solution, a part of the surface of the mortar turns white when about 10 hours have passed, and then the whole becomes white as time passes, and the surface of the mortar becomes a viscous solution. It became a state covered with.

  The mortar immersed in this acidic solution was first crushed to a size of about 20 to 30 cm square using a power shovel and further left in the acidic solution for 24 hours.

  Thereafter, the mortar was taken out from the acidic solution and put into a crusher to be crushed to about 1 to 2 cm square.

  The mortar after being treated with the acidic solution was in a very fragile state, and the crushing operation could be performed easily and with less energy.

  In addition, the mortar after being treated with an acidic solution has a surface coated with a viscous solution, and due to the viscosity and moisture of this viscous solution, the scattering of dust during the crushing operation is almost confirmed. There wasn't.

<Preparation of acidic solution>
15 parts by weight of a commercial synthetic detergent mainly composed of linear alkylbenzene sulfonic acid is added to 100 parts by weight of citric acid aqueous solution in which citric acid crystal particles and water are mixed at a weight ratio of 1: 1. An acidic solution (pH 0.9) was adjusted by adding 60 parts by weight of calcium acid.

<Cemented body>
Asbestos-containing slate was prepared as a hardened cement.

  When the asbestos-containing slate as a hardened cement was immersed in the acidic solution, a part of the slate surface turned white when about 10 hours passed, and then the whole became white as time passed. Was covered with a viscous solution.

  The slate immersed in this acidic solution was first crushed to a size of about 20 to 30 cm square using a power shovel, and further left in the acidic solution for 24 hours.

  Thereafter, the slate was taken out from the acidic solution and left for about 2 hours, and pulverized using a crusher until the size became about 1 to 3 mm square.

  The slate after being treated with the acidic solution was in a very fragile state, and the crushing operation could be performed easily and with less energy.

  Moreover, the slate after taking out from the acidic solution and leaving it for about 2 hours is in a state where the surface is coated with a glass coating, and as a result of the coating with the glass coating, most of the asbestos is scattered during the crushing operation. It was not confirmed.

<Preparation of coating for the water glass solution>
20 parts by weight of calcium silicate and lithium 20 parts by weight of silicic acid to prepare a coating water glass by dissolving 60 parts by weight of water.

<Curing agent>
An aqueous solution of sodium borate was used as a curing agent.

The total amount of sodium silicate and lithium silicate of the coating solution in the glass, a curing agent were mixed in sodium borate in the curing agent is 15 to 20 wt%, grinding it in the Example 2 The sprayed slate was sprayed in two portions so as to have a coating amount of about 200 to 400 g / m ^{2 with} respect to the flatly spread slate.

After coating, after curing for about 24 hours elapsed coating water glass is, the coated slate by glass film was put into heat-resistant vessel, a heating treatment was performed with a gas burner.
In addition, the processing temperature at this time was about 900 degreeC.

  And when the asbestos heat insulating material coated with the glass film after heat processing was observed, it was confirmed that it changed into the solid substance which makes a sound.

  When this solid was subjected to X-ray diffraction quantitative analysis of chrysotile, it was found that chrysotile was not detected at all.

  Thus, according to the method of the present invention, the hardened cement can be processed safely and easily, and even the hardened cement containing asbestos can be made harmless and safely disposed or recycled. It was confirmed that it can be processed into an already processed product that can be used for

Claims (9)

After treating the hardened cement with an acidic solution, it is crushed,
The cement hardened body after crushing is coated with a glass film by applying water glass for coating to the cement hardened body after crushing,
Then, the processing method of the hardened cement body which heat-processes at the processing temperature in the range of 800-1000 degreeC .   The processing method of the hardened cement body according to claim 1, wherein the hardened cement body is crushed within 3 cm square.   The processing method of the hardened cement body according to claim 1 or 2, wherein the acidic solution contains an organic acid as an acid component.   The method for treating a cement hardened body according to any one of claims 1 to 3, wherein a surfactant is further added to the acidic solution.   The processing method of the hardened cement body according to any one of claims 1 to 4, wherein the treatment with an acidic solution and the crushing operation are repeated.   The method for treating a hardened cement body according to any one of claims 1 to 5, wherein the acidic solution is further added with water glass for dust scattering prevention.   The method for treating a hardened cement body according to any one of claims 1 to 6, wherein a hardening agent is used together with the water glass for coating.   The method for treating a cement cured body according to claim 7, wherein the curing agent is an inorganic curing agent. An already-processed product produced as a result of being treated by the method for treating a cured cement body according to any one of claims 1 to 8 .