JP6088277B2 - How to use waste gypsum board - Google Patents

Description

  The present invention relates to a method for using waste gypsum board.

The amount of waste gypsum board waste, the main source of waste gypsum, is about 1.5 million tons per year, of which about 500,000 tons are scraps of new interior construction during production and houses. We are recycling. However, the remaining 1 million tons are discharged by renovation and demolition work of buildings such as houses, and are disposed of without being recycled. Since landfilled gypsum may generate hydrogen sulfide when it comes into contact with rainwater, landfilling of gypsum must be performed in a managed landfill, and disposal cost becomes a problem.
In this way, most of the gypsum derived from gypsum board waste is discarded without being recycled, and the cost and place of disposal itself become a problem, and the establishment of an effective method for using the gypsum is required. .

  Up to now, many proposals have been made on a method for treating waste gypsum obtained from gypsum board waste and the like. For example, a method of separating base paper from gypsum board waste and reusing the obtained gypsum has been proposed (see Patent Literature 1 and Patent Literature 2).

  However, in the methods described in Patent Document 1 and Patent Document 2, organic substances such as surfactant remain in the recovered gypsum, and a large amount of virgin gypsum (exhaust gas desulfurization gypsum) is reused. Unless it was mixed with chemical byproduct gypsum, natural dihydrate gypsum or natural anhydrous gypsum), it could not function as a gypsum board raw material. Patent Document 1 also discloses a method of incinerating waste gypsum with paper attached and reusing it as anhydrous gypsum. However, there is a problem that SOx is generated by incineration, There is room for improvement in that a separate water treatment step is required to make the same two-water-type gypsum as the flue gas desulfurization gypsum used in Japan.

On the other hand, a method in which waste gypsum is wet-treated and reused has also been proposed. For example, a method has been proposed in which α-type hemihydrate gypsum is produced by heat-treating gypsum board waste material that has not been crushed under pressure and wet conditions, and reused as a raw material for gypsum board (patent) Reference 3). According to this method, the board base paper and gypsum can be easily separated even with wet gypsum board waste. However, in the method described in Patent Document 3, since waste gypsum is not pulverized, the content of organic components such as surfactants contained in waste gypsum is sufficiently reduced when processing large shapes. The gypsum regenerated by this method could not be used unless it was mixed with a large amount of virgin gypsum as described above.
Furthermore, hemihydrate gypsum obtained by the above method has a very small average particle size of crystals and is a porous body. Therefore, in order to reuse this as a raw material for gypsum board, it is necessary to increase the ratio of water used in the slurry as compared with the slurry using virgin gypsum in order to ensure the fluidity of the gypsum slurry in the manufacturing process. is there. As a result, the gypsum board manufactured using 100% of the recycled gypsum by the above method has a serious problem that its strength is insufficient. Therefore, it is difficult to make all of the gypsum board raw material into recycled gypsum, and at present, it is only a partial replacement for virgin materials.

  Patent Document 4 discloses a gypsum board waste material in which gypsum in a gypsum board waste material is pulverized so that the total accumulated pore volume has a specific value, and then dissolved and precipitated in an aqueous medium containing seed crystal gypsum. It relates to a method for regenerating gypsum. However, although patent document 4 is examining in detail about reproducing | regenerating a waste gypsum board, the concrete examination about what kind of aspect the gypsum after reproduction | regeneration is utilized is not made.

Japanese Patent Laid-Open No. 10-286553 JP 2000-254531 A JP 2004-307321 A JP 2010-13304 A

  An object of the present invention is to provide a method for using a waste gypsum board that can use most of the recycled gypsum regenerated from the waste gypsum board as a useful resource and improve the reuse rate of the waste gypsum board.

  As a result of repeated studies to achieve the above-mentioned object, the inventors of the present invention have obtained dihydrate gypsum (regenerated dihydrate gypsum) obtained by crystallizing the gypsum component constituting the waste gypsum board after making it into semi-hydrate gypsum. ) Is found to be usable without problems in the use of gypsum, without being used together with virgin gypsum. In addition, it is separated from gypsum recovered from waste gypsum board by a method other than crystallization, for example, waste gypsum board. If the regenerated dihydrate gypsum is used in combination with the crushed gypsum component, or further dried or calcined, and the regenerated dihydrate gypsum, the whole amount is derived from waste gypsum board without using virgin gypsum. It has been found that the utilization rate of waste gypsum board can be greatly improved, and the present invention has been completed.

That is, according to the present invention, a baking step of baking the gypsum component constituting the waste gypsum board to obtain hemihydrate gypsum, a crystallization step of regenerating dihydrate gypsum by crystallization from the hemihydrate gypsum obtained in the baking step And the following steps of regenerating dihydrate gypsum obtained from the crystallization step;
(1) A process of using regenerated dihydrate gypsum as a cement-based solidifying agent raw material ,
(2) A step of firing the regenerated dihydrate gypsum to form regenerated hemihydrate gypsum and using it as a gypsum board raw material, cement raw material, cement-based solidifying material raw material, or gypsum-based solidifying material raw material
(3) firing the reproduction gypsum and playback anhydrite, as engineering to be used as a cement raw material or cement solidifying raw material,
There is provided a method of using the waste gypsum board characterized by including a post-treatment step for supplying to at least one of the above.

In the utilization method of the waste gypsum board of the present invention,
(A) The waste gypsum board was selected from the group consisting of scraps discharged during production or new interior construction of a building, and gypsum board waste discharged from the renovation, reconstruction or demolition site of the building Be at least one,
(B) Collecting step in which the gypsum component collects waste gypsum board; receiving step of collecting the collected waste gypsum board into waste gypsum board containing foreign matter and waste gypsum board not containing foreign matter; containing foreign matter Waste gypsum obtained by removing foreign matter from waste gypsum board; crushing and separating step of crushing waste gypsum board that does not contain foreign matter or from which foreign matter has been removed, and separates it into board base paper and crushed gypsum; Being crushed,
(C) The step (1) is a step of mixing recycled dihydrate gypsum with a pulverized part of the gypsum component constituting the waste gypsum board and using it as a cement-based solidifying material raw material .
(D) In the step (2), the regenerated hemihydrate gypsum is mixed with the gypsum board raw material, cement raw material, which is obtained by baking a part of the gypsum component constituting the waste gypsum board to obtain a semihydrate gypsum. The process is used as a cement-based solidifying material raw material or a gypsum-based solidifying material raw material,
(E) In the step (3), the recycled anhydrous gypsum is mixed with a material obtained by baking a part of the gypsum component constituting the waste gypsum board to obtain anhydrous gypsum, and then a cement raw material or a cement-based solidifying material raw material As a process used as
( F ) Furthermore, using flue gas desulfurization gypsum, chemical byproduct gypsum, natural dihydrate gypsum or natural anhydrous gypsum in at least one step of the above (1) to (3) ,
Is preferred.

  According to the utilization method of the present invention, gypsum regenerated from waste gypsum board is mainly reused as a gypsum board raw material, and further as a wide range of raw materials such as a cement raw material, a cement-based solidifying material raw material, or a gypsum-based solidifying material raw material. As a result, the reuse rate of waste gypsum board can be greatly improved, not only there is no waste of resources, but also the mass use of virgin gypsum is suppressed, and there is no need to perform special treatment such as water treatment. .

FIG. 1 is a diagram showing each step in the utilization method of the present invention.

  In the utilization method of the waste gypsum board of the present invention, first, pretreatment such as collection of waste gypsum board is performed as necessary, and then, dihydrate gypsum is regenerated from the waste gypsum board. The recycled dihydrate gypsum is used for various purposes in combination with the whole amount or waste gypsum crushed material that has not been recrystallized.

<Regeneration of dihydrate gypsum>
Examples of the above-mentioned waste gypsum board include gypsum board waste made of scraps or residue generated during the production of gypsum board or new interior construction of buildings, and gypsum discharged as building waste during renovation, renovation, and demolition work. There is board waste.
Such waste gypsum board mainly contains dihydrate gypsum (CaSO ₄ .2H ₂ O) as a gypsum component.
In the present invention, the method for producing recycled dihydrate gypsum includes a firing step of firing the gypsum component constituting the waste gypsum board to obtain hemihydrate gypsum, and crystallization from the hemihydrate gypsum obtained in the firing step. There is no particular limitation as long as it includes a crystallization step for regenerating hydrogypsum, and a known method is employed. As a typical method for producing regenerated dihydrate gypsum, the method disclosed in Patent Document 4 is suitable.

A method for regenerating dihydrate gypsum will be described below in accordance with the production method shown in Patent Document 4 above.
(Preprocessing)
First, waste gypsum board is collected from gypsum board production factories, construction sites, renovation / renovation / demolition sites (collection process). Some collected gypsum boards contain foreign materials such as metal pieces, so they are separated into waste gypsum boards containing foreign materials and waste gypsum boards that do not contain them (acceptance process). About the waste gypsum board containing a foreign material, it is preferable to remove a foreign material, for example with a sieve (foreign material removal process). The waste gypsum board that does not contain foreign substances or from which foreign substances have been removed is crushed to an appropriate particle size, and further, for example, the board base paper is preferably removed by the method described in Patent Documents 1 and 2 ( Crushing and separation step). Thus, waste gypsum crushed material is obtained.
The particle size of the waste gypsum crushed material used in the method of the present invention is not particularly limited, but the average particle size is preferably 0.5 to 50 mm from the viewpoint of ease of mechanical transport, More preferably, it is 1-20 mm. The average particle size can be measured by sieving.

(Baking)
Next, the waste gypsum crushed material obtained through the above pretreatment is adjusted to an appropriate size, for example, an average particle size of 0.5 to 50 mm, preferably 1 to 20 mm, and is supplied to the firing step. By calcining in this process, hemihydrate gypsum (CaSO ₄ · 1 / 2H ₂ O) is obtained.

(Pulverization)
The hemihydrate gypsum obtained by the firing step is preferably pulverized to have a volume average particle diameter of 0.5 to 30 μm, particularly 1 to 20 μm, if necessary.
This pulverization step can be performed using a conventionally known apparatus such as a pin mill, a ball mill, or a bead mill.

  The firing step and the pulverization step may each be performed in a batch manner, or may be performed in a continuous process. Furthermore, each may be an independent process, or may be a process in which both processes are connected in series. Furthermore, these steps may be independent of the dihydrate gypsum crystallization step described later, or may be a continuous step.

(Crystallization)
In the subsequent crystallization step, hemihydrate gypsum obtained as described above is dissolved in an aqueous medium containing dihydrate gypsum as seed crystal gypsum, and then dihydrate gypsum is precipitated as regenerated gypsum.
The initial particle size of the seed crystal gypsum is preferably 10 to 60 μm, more preferably 20 to 40 μm. The abundance ratio of the seed crystal is preferably 100 to 400 g / L, more preferably 200 to 300 g / L.

The aqueous medium for dissolving the hemihydrate gypsum is preferably water, and the pH is preferably in the range of 4 to 8 from the viewpoint of maintaining an appropriate gypsum precipitation rate. The temperature of the aqueous medium is preferably 90 ° C. or less, and more preferably 50 to 80 ° C.
In order to satisfy each of the above conditions, hemihydrate gypsum is dissolved in the seed crystal gypsum-containing slurry, and when stirred for an appropriate time, dihydrate gypsum precipitates around the seed crystal gypsum to obtain regenerated dihydrate gypsum. Can do.

  Regenerated dihydrate gypsum can be separated from the aqueous medium by a known filtration method. For example, a method of separating water from a rotary screen, a drum filter, a disk filter, a Nutsche filter, a filter press, a screw press, a tube press or the like; a centrifugal separator such as a screw decanter or a screen decanter; Can do. The separated dihydrate gypsum that has been separated is appropriately dried and used according to the form of use in a post-processing step described later. The collected filtrate can be recycled and reused in an aqueous medium for dissolving and precipitating hemihydrate gypsum.

In the crystallization step, dissolution and precipitation of gypsum may be performed in a batch manner or a continuous process, but it is preferably performed in a continuous process from the viewpoint that the advantages of the present invention are particularly exhibited. Advantages of the present invention include a process comprising at least a pulverization step and a dissolution and precipitation step of gypsum as continuous processes, connecting them in series, and circulating a part of the obtained regenerated dihydrate gypsum as seed crystal gypsum. Is particularly preferable from the viewpoint of exhibiting the maximum effect. In the present invention, since the dissolution and precipitation of gypsum occurs stably in the presence of seed crystal gypsum, the particle size of the gypsum increases with time in the reaction tank (dissolution / precipitation tank). The surface area of the seed crystal in the reaction vessel decreases with the increase in the particle size of this gypsum, but it is stable due to measures such as grinding the gypsum in the reaction vessel or supplying seed crystal gypsum with a small particle size from outside the system. Can produce a certain amount of gypsum.
Thus, dihydrate gypsum is regenerated from the waste gypsum board.

<Post-processing process: Use of recycled gypsum>
The recycled dihydrate gypsum obtained by the above process is used as at least one of a gypsum board raw material, a cement raw material, a cement-based solidifying material raw material, and a gypsum-based solidifying material raw material in a post-processing step, and blast furnace slag It can also be used as an additive for fine powder. The regenerated dihydrate gypsum may be used as it is, but may be fired and used as hemihydrate gypsum or anhydrous gypsum (CaSO ₄ ) depending on the purpose.
In particular,
(1) Regenerated dihydrate gypsum can be used as a cement raw material or a cement-based solidifying material raw material,
(2) Regenerated hemihydrate gypsum can be used as a gypsum board raw material, cement raw material, cement-based solidifying material raw material or gypsum-based solidifying material raw material,
(3) Regenerated anhydrous gypsum can be used as a cement raw material or a cement-based solidifying material raw material,
(4) Regenerated dihydrate gypsum can be used as it is, or calcined to obtain regenerated hemihydrate gypsum or regenerated anhydrous gypsum, which can be used as an additive for blast furnace slag fine powder.

  As is apparent from the above description, regenerated dihydrate gypsum, regenerated hemihydrate gypsum, or regenerated anhydrous gypsum can be used as the cement raw material, and in particular, regenerated dihydrate gypsum is preferable from the viewpoint of the function of adjusting the curing rate. is there. When using regenerated hemihydrate gypsum and / or regenerated anhydrous gypsum, it is preferably used in combination with dihydrate gypsum. The mixing ratio of dihydrate gypsum in the whole raw material gypsum is preferably 30% by weight or more, and more preferably 50% by weight or more. Even when regenerated dihydrate gypsum, regenerated hemihydrate gypsum, and regenerated anhydrous gypsum are used in combination, it is preferable to use them together in this proportion.

Further, as the cement-based solidifying material raw material, regenerated dihydrate gypsum, regenerated hemihydrate gypsum, or regenerated anhydrous gypsum can be used, but regenerated dihydrate gypsum and / or regenerated anhydrous gypsum are preferable. When regenerated hemihydrate gypsum is used, it is preferably used in combination with dihydrate gypsum and / or anhydrous gypsum. In this case, the proportion of hemihydrate gypsum in the entire raw gypsum is preferably 50% by weight or less. Even when regenerated dihydrate gypsum, regenerated hemihydrate gypsum, and regenerated anhydrous gypsum are used in combination, it is preferable to use them together in this proportion.
As the gypsum board raw material or the gypsum-based solidifying material raw material, recycled hemihydrate gypsum is suitable. As an additive for blast furnace slag fine powder, any of recycled dihydrate gypsum, regenerated hemihydrate gypsum, and regenerated anhydrous gypsum can be suitably used.

  In the present specification, regenerated dihydrate gypsum itself, regenerated semihydrate gypsum obtained by firing regenerated dihydrate gypsum, or regenerated anhydrous gypsum obtained by firing regenerated dihydrate gypsum may be collectively referred to as “gypsum derived from regenerated dihydrate gypsum”. is there.

Thus, in the utilization method of the present invention, gypsum derived from regenerated dihydrate gypsum can be used as a gypsum component for various purposes of use, and in addition, in the utilization, unlike conventional reuse methods, the amount There are no restrictions. That is, if it can be covered quantitatively, the entire amount can be made from regenerated dihydrate gypsum. In this way, by using gypsum derived from recycled dihydrate gypsum as the main raw material, it is possible to improve the reuse rate of waste gypsum board, thereby reducing the amount of landfill and reducing the burden on the environment. it can. Further, since the amount of virgin gypsum used is more expensive than recycled dihydrate gypsum, there is a commercial merit that the economic burden is reduced. In particular, when gypsum derived from recycled dihydrate gypsum is used as a gypsum component of a gypsum board raw material, the amount of virgin gypsum used can be greatly reduced.
Virgin gypsum means flue gas desulfurization gypsum, chemical byproduct gypsum, natural dihydrate gypsum, or natural anhydrous gypsum.

  In the following, each of the specific cases is divided into (1) when used as regenerated dihydrate gypsum, (2) when used as regenerated hemihydrate gypsum, and (3) when used as regenerated anhydrous gypsum. Various usage modes will be described.

(1) Utilization in Regenerated Dihydrate Gypsum Hereinafter, as shown in FIG. 1, in the post-treatment process of the present invention, the regenerated dihydrate gypsum is not made into hemihydrate gypsum or anhydrous gypsum. The case where it is used as at least one of a cement raw material and a cement-based solidifying material raw material will be described.

(1-1) Cement raw material First, the case where regenerated dihydrate gypsum itself is used as a cement raw material is demonstrated. The cement raw material means a known cement raw material mainly composed of limestone, and specifically refers to limestone, clayey raw material, siliceous raw material, iron oxide raw material, and gypsum. Gypsum is used to adjust the setting speed of cement. Generally, flue gas desulfurization gypsum generated by flue gas desulfurization in thermal power plants and by-product gypsum are used.

  As described above, as a cement raw material, regenerated dihydrate gypsum is more preferably used than regenerated hemihydrate gypsum and regenerated anhydrous gypsum from the viewpoint of the function of adjusting the curing rate. As a concrete process when regenerated dihydrate gypsum is used as a cement raw material, limestone, clay, silica stone and iron oxide are mixed at a certain ratio, the mixture is dried with a dryer, and pulverized with a raw material mill (pulverizer). . The raw material powder after pulverization is stored in a silo. The raw material powder is preheated with a preheater in order to improve the firing efficiency, is gradually passed through a firing kiln, and is fired at a high temperature of 1450 ° C. or higher. Thereby, the raw material powder causes a chemical change in the kiln, and a clinker which is a collection of compounds having hydraulic properties can be obtained. After air-cooling the clinker, the regenerated dihydrate gypsum and the clinker and the mixed material are mixed at a certain ratio, and these are pulverized with a mill (pulverizer) to obtain a cement.

  At this time, the regenerated dihydrate gypsum may be mixed as it is without being dried after filtration. The water content of the regenerated dihydrate gypsum after filtration is only 5 to 15% by weight, and even if such regenerated dihydrate gypsum is mixed and pulverized with the clinker, the moisture is dissipated during the pulverization process, so the cement is hardened. It is because it does not affect. However, when used as a cement raw material, it is preferable to use regenerated dihydrate gypsum that has been dried after filtration. What is necessary is just to dry the regenerated dihydrate gypsum after filtration for 30 to 60 minutes at 60-80 degreeC using a warm air dryer, when drying, for example.

  As the cement raw material, only recycled dihydrate gypsum may be used without mixing with waste gypsum crushed material or virgin gypsum. Conventional reclaimed gypsum contains a lot of impurities, and these impurities affect the hardening of the cement, making it difficult to adjust the setting time, etc., so only a small amount could be used. Dihydrate gypsum is very pure and does not have this concern. Moreover, compared with the conventional reuse method which uses virgin gypsum as a main raw material, there exists an advantage that the reuse rate of waste gypsum board rises and the amount of landfill of a waste gypsum board reduces, ie, an environmental load reduces.

  Regenerated dihydrate gypsum can also be used by mixing with waste gypsum crushed material or virgin gypsum. When regenerated dihydrate gypsum and waste gypsum crushed material are used, advantages of using only regenerated dihydrate gypsum are ensured, and further, it is advantageous in terms of raw material procurement cost and energy. Therefore, depending on the quality of the target cement, the combined use of recycled dihydrate gypsum and waste gypsum crushed material is suitable.

  When using recycled dihydrate gypsum and waste gypsum crushed material, crush some of the gypsum components that make up the waste gypsum board, remove the base paper as necessary, and store it separately. Dihydrate gypsum is regenerated from the components, and the regenerated dihydrate gypsum and waste gypsum crushed material and clinker are kneaded. The proportion of the recycled dihydrate gypsum in the raw gypsum component is preferably 70 to 95% by weight, particularly preferably 85 to 95% by weight. When a large amount of the crushed gypsum component is used, impurities contained in the crushed gypsum component affect the behavior of cement hardening.

  On the other hand, when using regenerated dihydrate gypsum and virgin gypsum, these may be mixed with clinker. Virgin gypsum may be dried in advance or may not be dried. In the conventional reuse method, since a large amount of virgin gypsum had to be blended, the amount of recycled gypsum used was very limited. However, in the utilization method of the present invention, there is no such limitation. A lot of water gypsum can be blended. The proportion of the specific recycled dihydrate gypsum is preferably 50 to 95% by weight, particularly preferably 70 to 95% by weight, based on the raw gypsum component. Increasing the proportion of virgin gypsum causes disadvantages in terms of the reuse rate and economical efficiency of waste gypsum board.

As a cement raw material, a mixture of recycled dihydrate gypsum, virgin gypsum and waste gypsum crushed material can also be used. The proportion of the recycled dihydrate gypsum in the raw gypsum component is preferably 50 to 95% by weight, particularly preferably 70 to 95% by weight.
Even if only regenerated dihydrate gypsum is used or virgin gypsum and / or waste gypsum crushed material is mixed, the proportion of the gypsum component in the entire cement raw material is 1 in terms of SO _3. 0.0 to 4.0% by weight is preferred.

(1-2) Cement-based solidifying material raw material Next, the case where the recycled dihydrate gypsum itself is used as the cement-based solidifying material raw material will be described. Cement-based solidification material is a variety of materials that use cement as a base material in order to cope with soil conditions that are difficult to solidify with conventional lime, cement, etc. and on-site conditions, such as soft ground that cannot support buildings and soil that contains many corrosive substances. An active ingredient is added.

As described above, regenerated dihydrate gypsum is more preferably used as a cement-based solidifying material raw material than regenerated hemihydrate gypsum, and is used as well as regenerated anhydrous gypsum.
When using recycled dihydrate gypsum as a raw material for cement-based solidification materials, specifically, by mixing clinker, active ingredients selected according to the soil and site, and recycled dihydrate gypsum at a certain ratio. A cement-based solidified material is obtained. Regenerated dihydrate gypsum may be used as it is after drying, or may be used after pulverization, but generally it is used as it is after drying. Examples of the active ingredient include slaked lime, lightweight dolomite, blast furnace slag, limestone powder, fly ash, silica fine powder and the like.

  The regenerated dihydrate gypsum is preferably used after filtration and drying. If drying is not performed, moisture (moisture other than crystal water) adhering to the regenerated dihydrate gypsum reacts with clinker or various active ingredients, and curing begins, preserving cement-based solidified material Stability is impaired. The drying may be performed by the same method as (1-1) cement raw material.

  As a raw material for the cement-based solidifying material, only recycled dihydrate gypsum may be used without mixing waste gypsum crushed material or virgin gypsum. Conventional regenerated gypsum contains a lot of impurities, which may affect the hardening of the solidified material, but the regenerated dihydrate gypsum obtained by the method of the present invention has a very high purity. There is no such worry. Moreover, compared with the conventional reuse method which uses virgin gypsum as a main raw material, there exists an advantage that the reuse rate of a waste gypsum board improves and an environmental load is reduced. Furthermore, there is an economic advantage because expensive virgin gypsum is not used.

  Regenerated dihydrate gypsum can also be used by mixing with waste gypsum crushed material or virgin gypsum. The combined use of recycled dihydrate gypsum and waste gypsum crushed material is advantageous in terms of energy saving and saving while utilizing the advantages of using only recycled dihydrate gypsum. Therefore, the combined use of recycled dihydrate gypsum and waste gypsum crushed material is suitable depending on the quality of the intended cementitious solidifying material.

  When regenerated dihydrate gypsum and waste gypsum crushed material are used, (1-1) the same separation, crushing, regeneration of dihydrate gypsum, etc. as in the case of cement raw materials. Mix crushed gypsum with clinker and active ingredients. The proportion of the recycled dihydrate gypsum in the raw gypsum component is preferably 70 to 95% by weight, particularly preferably 85 to 95% by weight. When a large amount of waste gypsum crushed material is used, impurities contained in the waste gypsum crushed material may affect the hardening behavior of the solidified material. Furthermore, since the cement-based solidified material is sprayed and mixed directly into the soil, impurities may flow out from the rainwater into the soil.

  On the other hand, when regenerated dihydrate gypsum and virgin gypsum are used, they may be kneaded with clinker and active ingredients. The virgin gypsum used is dried beforehand. Unlike the conventional reuse method, in the utilization method of the present invention, it is not necessary to use a large amount of virgin gypsum, and a large amount of regenerated dihydrate gypsum can be blended. Is preferably 50 to 95% by weight, particularly preferably 70 to 95% by weight, based on the gypsum component of the raw material. By suppressing the proportion of virgin gypsum, the recycling rate of waste gypsum board can be sufficiently improved, the amount of waste gypsum board being landfilled can be reduced, and the cost of obtaining virgin gypsum can be suppressed.

As a raw material for the cement-based solidifying material, a mixture of recycled dihydrate gypsum, virgin gypsum and waste gypsum crushed material can also be used. The proportion of the recycled dihydrate gypsum in the raw gypsum component is preferably 50 to 95% by weight, particularly preferably 70 to 95% by weight.
Even if only regenerated dihydrate gypsum is used or virgin gypsum and / or waste gypsum crushed material is mixed, the proportion of the gypsum component in the entire cement-based solidifying material raw material is equivalent to SO ₃ And 1.0 to 8.0% by weight is preferable.

(2) Utilization in regenerated hemihydrate gypsum As shown in FIG. 1, in the post-treatment process of the present invention, regenerated hemihydrate gypsum obtained by firing regenerated dihydrate gypsum is used as a gypsum board raw material, cement raw material, cement The case where it uses as at least one of a system solidification material raw material and a gypsum system solidification material raw material is demonstrated.
In order to obtain regenerated hemihydrate gypsum, although the conditions vary depending on the apparatus or the like, generally, the regenerated dihydrate gypsum may be heated at a temperature of 100 to 200 ° C. for 2 to 60 minutes.

(2-1) Gypsum board raw material First, the case where it uses as a gypsum board raw material is demonstrated. Gypsum board is a plate-like body made of gypsum board base paper with a core composed mainly of hemihydrate gypsum, and is excellent for fireproofing, sound insulation, workability and economic efficiency. Widely used in buildings as an interior material.

  Regenerated hemihydrate gypsum may be used as a gypsum board raw material according to a conventionally known method. For example, regenerated hemihydrate gypsum is pulverized and kneaded with an adhesion aid, a curing accelerator, foam for reducing weight, other additives, and further, an admixture and water, and the resulting slurry May be poured between upper and lower base paper for gypsum board, formed into a plate shape, then cured, roughly cut, forced dried, and cut into product dimensions.

  As the gypsum board raw material, only recycled hemihydrate gypsum may be used without mixing waste gypsum crushed material or virgin gypsum. Since the regenerated hemihydrate gypsum is obtained by heating the regenerated dihydrate gypsum obtained by crystallization, it has high purity and there is no fear of reducing the strength of the gypsum board. Moreover, compared with the conventional reuse method which uses virgin gypsum as a main raw material, it is preferable also from a viewpoint of the reuse rate and economical efficiency of waste gypsum board. Furthermore, regenerated hemihydrate gypsum is obtained by crystallizing the gypsum component contained in the waste gypsum board to increase its purity, and the use of the regenerated hemihydrate gypsum thus obtained as a raw material for gypsum board is From the viewpoint that the utilization method of the invention circulates, it is very preferable.

Regenerated hemihydrate gypsum can also be used by mixing with waste gypsum crushed material or virgin gypsum.
As the waste gypsum crushed material, part of the gypsum component constituting the waste gypsum board was crushed, and the base paper was removed as necessary, that is, the dihydrate gypsum state was baked to make a half-water gypsum (Hereinafter sometimes referred to as “waste hemihydrate gypsum”).
Similarly, as virgin gypsum, dihydrate gypsum in the form of calcined hemihydrate gypsum (hereinafter sometimes referred to as “virgin hemihydrate gypsum”) is used.

Using recycled hemihydrate gypsum and waste hemihydrate gypsum makes use of the benefits of using recycled hemihydrate gypsum alone, while reducing the cost and energy required to procure gypsum raw materials. There is also merit from. Therefore, depending on the quality of the target gypsum board, the combined use of recycled hemihydrate gypsum and waste hemihydrate gypsum is suitable.
In order to use recycled hemihydrate gypsum and waste hemihydrate gypsum, first, part of the gypsum components that make up the waste gypsum board are crushed, the base paper is removed and fired as necessary, and stored separately. Then, after regenerating dihydrate gypsum from the remaining gypsum component and firing it into semi-water gypsum, the regenerated half-water gypsum and the stored waste hemi-water gypsum are used as an adhesion aid, a curing accelerator, etc. And knead. Alternatively, a part of the gypsum component constituting the waste gypsum board is crushed, the base paper is removed as necessary, and stored separately, and the dihydrate gypsum is regenerated from the remaining gypsum component, and the recycled dihydrate Gypsum and waste gypsum crushed material that is dihydrate gypsum are mixed, and the mixture is baked to make semi-water gypsum, and then kneaded with an adhesion aid, a curing accelerator, or the like.

  Unlike the conventional reuse method, in the utilization method of the present invention, it is not necessary to use a large amount of virgin gypsum, that is, the amount of regenerated hemihydrate gypsum is not limited, but a specific regenerated hemihydrate gypsum occupies. The proportion is preferably 70 to 95% by weight, particularly preferably 85 to 95% by weight, based on the gypsum component of the raw material. When a large amount of waste hemihydrate gypsum is used, the strength of the gypsum board decreases due to the remaining surfactant and the like.

  On the other hand, when regenerated hemihydrate gypsum and virgin hemihydrate gypsum are used, they may be kneaded with an adhesion aid, a curing accelerator or the like and used for the production of gypsum board. The proportion of the recycled gypsum component in the raw gypsum component is preferably 50 to 95% by weight, particularly preferably 70 to 95% by weight, from the viewpoint of the reuse rate of waste gypsum board and economy.

  Recycled hemihydrate gypsum, virgin hemihydrate gypsum, and waste hemihydrate gypsum can be used as the gypsum board raw material, and these can be kneaded with an adhesion aid or the like. The proportion of the recycled hemihydrate gypsum in the raw gypsum component is preferably 50 to 95% by weight, particularly preferably 70 to 95% by weight.

(2-2) Cement raw material Next, the case where regenerated hemihydrate gypsum is used as a cement raw material is demonstrated. In this case, (1-1) by producing a clinker by the same method as when using regenerated dihydrate gypsum as a cement raw material, mixing and pulverizing a gypsum component such as regenerated hemihydrate gypsum and a clinker or a mixture, Cement is obtained.
As already described, as the gypsum used as the cement raw material, regenerated dihydrate gypsum is more suitable than regenerated hemihydrate gypsum, but regenerated hemihydrate gypsum can also be used without problems.

In particular, regenerated hemihydrate gypsum is preferably mixed with dihydrate gypsum. That is, the regenerated hemihydrate gypsum is preferably used by mixing with waste gypsum crushed material that is dihydrate gypsum or virgin gypsum that is dihydrate gypsum. If necessary, anhydrous gypsum may be further mixed. Further, a part of the regenerated hemihydrate gypsum may be replaced with waste hemihydrate gypsum or virgin hemihydrate gypsum. The mixing ratio of each gypsum component is preferably set so that the proportion of dihydrate gypsum in the whole raw gypsum is 30% by weight or more, and more preferably 50% by weight or more.
Incidentally, even in the case of using only the reproduction hemihydrate gypsum, even when mixing the virgin plaster and / or gypsum crushed, the ratio of gypsum component in the cement raw material, converted to SO _3, 1. 0 to 4.0 weight is preferred.

(2-3) Cement-based solidifying material raw material Next, the case where regenerated hemihydrate gypsum is used as the cement-based solidifying material raw material will be described. As a specific method of use, a cement-based solidified material can be obtained by mixing clinker, active ingredient, and regenerated hemihydrate gypsum at a certain ratio in the same manner as in (1-2). As an active ingredient, the same thing as the case where (1-2) reproduction | regeneration dihydrate gypsum is utilized as a cement-type solidification material raw material is mentioned.

As described above, regenerated dihydrate gypsum and / or regenerated anhydrous gypsum is more preferable as the gypsum used as a raw material for the cement-based solidifying material, but regenerated hemihydrate gypsum can be used without any problem.
In particular, the regenerated hemihydrate gypsum is preferably mixed with dihydrate gypsum and / or anhydrous gypsum. That is, the recycled hemihydrate gypsum is preferably used by mixing with waste gypsum crushed material that is dihydrate gypsum or virgin gypsum that is dihydrate gypsum or anhydrous gypsum. Further, a part of the regenerated hemihydrate gypsum may be replaced with waste hemihydrate gypsum or virgin hemihydrate gypsum. In this case, the proportion of hemihydrate gypsum in the total raw material gypsum is preferably 50% by weight or less.
Even if only regenerated hemihydrate gypsum is used or virgin gypsum and / or waste gypsum crushed material is mixed, the proportion of the gypsum component in the cement-based solidifying material raw material is calculated in terms of SO ₃ . 1.0-8.0 weight% is preferable.

(2-4) Gypsum-based solidifying material raw material Next, the case where regenerated hemihydrate gypsum is used as the gypsum-based solidifying material raw material will be described. The gypsum-based solidified material is composed of hemihydrate gypsum as a main component and contains various active ingredients. Since it is neutral, it does not affect the pH of the improved soil and is environmentally friendly. Recycled hemihydrate gypsum is used as the gypsum-based solidifying material raw material.

The gypsum-based solidifying material raw material can be obtained by mixing regenerated hemihydrate gypsum and various active ingredients at a certain ratio, and powdering them with a mill (pulverizer).
As an active ingredient, a hardening accelerator, a retarder, a flocculant, a pH adjuster etc. can be mentioned, for example.

  The recycled hemihydrate gypsum may be used alone without mixing the waste hemihydrate gypsum or virgin hemihydrate gypsum. Regenerated hemihydrate gypsum is obtained by heating the regenerated dihydrate gypsum obtained by the above-described regeneration method, and therefore contains almost no impurities. Therefore, there is no worry that neutrality cannot be maintained due to impurities. Moreover, compared with the conventional reuse method using virgin hemihydrate gypsum as a main raw material, the reuse rate of waste gypsum board can be improved, the amount of waste gypsum landfilled can be reduced, and the burden on the environment can be reduced. In addition, there is an economic advantage because more expensive virgin hemihydrate gypsum is not used.

  Regenerated hemihydrate gypsum can be used by mixing with waste hemihydrate gypsum or virgin hemihydrate gypsum. Use of recycled hemihydrate gypsum and waste hemihydrate gypsum has advantages from the viewpoint of energy saving and saving while utilizing the advantages of using only regenerated hemihydrate gypsum. Therefore, depending on the quality of the target gypsum-based solidifying material, the combined use of recycled hemihydrate gypsum and waste hemihydrate gypsum is suitable.

  When using regenerated hemihydrate gypsum and waste hemihydrate gypsum, the proportion of the regenerated hemihydrate gypsum in the raw gypsum component is preferably 70 to 95% by weight, particularly preferably 80 to 95% by weight. When a large amount of waste hemihydrate gypsum is used, impurities in the waste gypsum crushed material may affect the pH. Furthermore, since the gypsum-based solidified material is directly applied to and mixed with the soil, impurities may flow out due to rainwater.

  On the other hand, when using regenerated hemihydrate gypsum and virgin hemihydrate gypsum, these may be mixed with various active ingredients. In the present invention, unlike the conventional recycling method, it is not necessary to add a large amount of virgin gypsum, that is, there is no particular limitation on the amount of regenerated hemihydrate gypsum. The proportion occupied by is preferably 50 to 95% by weight, particularly preferably 70 to 95% by weight, based on the gypsum component of the raw material. This is because if the proportion of the virgin hemihydrate gypsum is too large, the reuse rate of the waste gypsum board is not improved, and it is not economically preferable.

  As a raw material for the gypsum-based solidifying material, a mixture of regenerated hemihydrate gypsum, virgin hemihydrate gypsum, and waste hemihydrate gypsum can also be used. The proportion of the recycled hemihydrate gypsum in the raw gypsum component is preferably 50 to 95% by weight, particularly preferably 70 to 95% by weight.

(3) Utilization in regenerated anhydrous gypsum As shown in FIG. 1, in the post-treatment process of the present invention, regenerated anhydrous gypsum obtained by firing regenerated dihydrate gypsum is used as a cement raw material and a cement-based solidifying material raw material. The case where it is used as at least one will be described.
In order to obtain regenerated anhydrous gypsum, although the conditions differ depending on the apparatus or the like, generally, the regenerated dihydrate gypsum may be heated at a temperature of 400 to 900 ° C. for 30 to 90 minutes.

(3-1) Cement raw material The case where regenerated anhydrous gypsum is used as a cement raw material will be described. In this case, the clinker is produced by the same method as (1-1) regenerated dihydrate gypsum or (2-2) regenerated hemihydrate gypsum as a cement raw material, and the regenerated anhydrous gypsum is mixed with the clinker or mixed material. Cement is obtained by grinding.

  As the gypsum used as a cement raw material, dihydrate gypsum is more suitable from the viewpoint of the function of adjusting the curing rate, but there is no problem even if anhydrous gypsum is used.

In particular, the regenerated anhydrous gypsum is preferably used by mixing with dihydrate gypsum. Moreover, you may mix hemihydrate gypsum as needed. Further, a part of the regenerated anhydrous gypsum may be replaced with a waste gypsum crushed product made of anhydrous gypsum or a virgin gypsum made of anhydrous gypsum. In this case, the proportion of each gypsum component should be determined so that the proportion of dihydrate gypsum in the total raw material gypsum is preferably 30% by weight or more, particularly preferably 50% by weight or more.
Even if only regenerated anhydrous gypsum is used or virgin gypsum and / or waste gypsum crushed material is mixed, the proportion of the gypsum component in the cement raw material is 1.0 in terms of SO _3. -4.0 wt% is preferred.

(3-2) Cement-based solidifying material raw material Next, the case where regenerated anhydrous gypsum is used as the cement-based solidifying material raw material will be described. As a specific method of use, a cement-based solidified material is obtained by mixing clinker, active ingredient, and regenerated anhydrous gypsum at a certain ratio in the same manner as in (1-2). As an active ingredient, the same thing as the case where (1-2) regenerated dihydrate gypsum is used as a cement system solidification material raw material is mentioned.

  As the gypsum used as a raw material for the cement-based solidifying material, anhydrous gypsum can be used more preferably than regenerated hemihydrate gypsum, and to the same extent as regenerated dihydrate gypsum.

  As a raw material for the cement-based solidifying material, only regenerated anhydrous gypsum may be used without being mixed with waste gypsum crushed material or virgin gypsum. In the present invention, even if only regenerated anhydrous gypsum is used, there is no fear that impurities react with various active ingredients or affect the hardening of the solidified material. Moreover, compared with the conventional reuse method which uses virgin gypsum as a main raw material, there exists a merit from a viewpoint of the reuse rate of waste gypsum board, and an economical viewpoint.

Regenerated anhydrous gypsum can also be used by mixing with waste gypsum crushed material or virgin gypsum.
As the waste gypsum crushed material, the gypsum component that constitutes the waste gypsum board may be partially crushed and the base paper removed as necessary. For this reason, it is preferable to use a material obtained by firing this into anhydrous gypsum.
The use of regenerated anhydrous gypsum and waste gypsum pulverized material or its anhydrous gypsum has advantages in terms of energy saving and saving while taking advantage of the advantages of using only regenerated anhydrous gypsum. Therefore, depending on the quality of the intended cementitious solidifying material, the combined use of recycled anhydrous gypsum and waste gypsum crushed material or anhydrous gypsum thereof is suitable.

  When the regenerated anhydrous gypsum and the waste gypsum crushed material or the anhydrous gypsum are used, the proportion of the regenerated anhydrous gypsum in the raw gypsum component is preferably 70 to 95% by weight, particularly preferably 80 to 95% by weight. When a large amount of waste gypsum crushed material or anhydrous gypsum thereof is used, impurities contained in the waste gypsum crushed material may affect the hardening behavior of the solidified material or may react with various active ingredients. Furthermore, since the cement-based solidified material is sprayed and mixed directly on the soil, there is a possibility that impurities will flow out by rainwater.

  On the other hand, when regenerated anhydrous gypsum and virgin gypsum are used, they may be kneaded with clinker and active ingredients. In the present invention, unlike the conventional recycling method, it is not necessary to add a large amount of virgin gypsum, that is, there is no particular limitation on the amount of regenerated anhydrous gypsum. The proportion is preferably 50 to 95% by weight, particularly preferably 70 to 95% by weight, based on the gypsum component of the raw material. An excessively large proportion of virgin gypsum is not preferable from the viewpoint of the reuse rate and economical efficiency of waste gypsum board.

Recycled anhydrous gypsum, virgin gypsum, waste gypsum crushed material, or a mixture of anhydrous gypsum can also be used as a raw material for the cement-based solidifying material. The proportion of the recycled gypsum component in the raw gypsum component is preferably 50 to 95% by weight, particularly preferably 80 to 95% by weight.
Even when only regenerated anhydrous gypsum is used, or when virgin gypsum and / or waste gypsum crushed material or anhydrous gypsum is mixed, the proportion of the gypsum component in the cement-based solidified material raw material is SO _In terms of _3, it is preferably 1.0 to 8.0% by weight.

  In the utilization method of the waste gypsum board of the present invention, as a post-treatment step, (1) a step of using the regenerated dihydrate gypsum as a cement raw material or a cement-based solidifying material raw material, and (2) a regenerated hemihydrate gypsum as a gypsum board raw material At least one of the step of using the cement raw material, the cement-based solidifying material raw material or the gypsum-based solidifying material raw material, and (3) the step of using the regenerated anhydrous gypsum as the cement raw material or the cement-based solidifying material raw material is selected. That is, one of the steps (1), (2), and (3) may be selected, or as shown in FIG. The part is fired to form regenerated hemihydrate gypsum and / or regenerated anhydrous gypsum, and regenerated dihydrate gypsum itself, regenerated hemihydrate gypsum and / or regenerated anhydrous gypsum are selected from (1), (2) and (3) You may use for a several process.

(4) Additive for blast furnace slag fine powder In addition to the above (1) to (3), in the post-treatment process of the present invention, gypsum derived from regenerated dihydrate gypsum, that is, regenerated dihydrate gypsum, regenerated hemihydrate gypsum, regenerated Anhydrous gypsum or a mixture thereof can also be used as an additive for blast furnace slag fine powder added to blast furnace slag fine powder which is a raw material of blast furnace slag cement, for example.
Blast-furnace slag fine powder is crushed blast furnace granulated slag added with gypsum. It is the one that has been converted to water (granulated). Slag is debris that separates from the molten metal and emerges during metal smelting.

When using gypsum derived from regenerated dihydrate gypsum as an additive for blast furnace slag fine powder, add gypsum derived from regenerated dihydrate gypsum to blast furnace granulated slag and mix and pulverize it according to a conventionally known method. Good. Gypsum derived from regenerated dihydrate gypsum may be used alone or in combination with waste gypsum crushed material or virgin gypsum. The proportion of gypsum derived from recycled dihydrate gypsum in the raw gypsum component is preferably 50 to 95% by weight.
Whether the gypsum derived from regenerated dihydrate gypsum is used alone or in combination with crushed waste gypsum or virgin gypsum, the amount of gypsum component added to the blast furnace slag fine powder is 0.5 to 4.0 in terms of SO _3. It is preferable that it is weight%. When the addition amount is too large, for example, when blast furnace slag fine powder is used as a raw material for the blast furnace slag cement, there is a case where the setting of the cement becomes slow or the strength of the blast furnace slag cement is lowered.

Claims (7)

Obtained from the calcination step of firing the gypsum component constituting the waste gypsum board to obtain hemihydrate gypsum, the crystallization step of regenerating dihydrate gypsum from the hemihydrate gypsum obtained in the calcination step, and the crystallization step A method for using waste gypsum board, comprising a post-treatment step of supplying the regenerated dihydrate gypsum to at least one of the following steps.
(1) A step of using regenerated dihydrate gypsum as a cement-based solidifying material raw material ;
(2) A step of firing the regenerated dihydrate gypsum to form regenerated hemihydrate gypsum, which is used as a gypsum board raw material, a cement raw material, a cement-based solidifying material raw material, or a gypsum-based solidifying material raw material;
(3) A step of firing the regenerated dihydrate gypsum to form regenerated anhydrous gypsum and using it as a cement raw material or a cement-based solidifying material raw material ;   The waste gypsum board is at least one selected from the group consisting of scrap materials discharged during production or new interior construction of a building, and gypsum board waste material discharged from the site of renovation, reconstruction or demolition of a building The usage method of the waste gypsum board of Claim 1 which is.   A collecting step in which the gypsum component collects waste gypsum board; a receiving step in which the collected waste gypsum board is divided into a waste gypsum board containing foreign matter and a waste gypsum board not containing foreign matter; and a waste gypsum board containing foreign matter. A waste gypsum crushed material obtained by crushing and separating step of crushing waste gypsum board that does not contain foreign material or removed foreign material and separate it into board base paper and gypsum crushed material; A method for using the waste gypsum board according to claim 1. The step (1) is a step in which the regenerated dihydrate gypsum is mixed with a part of the gypsum component constituting the waste gypsum board and used as a cement-based solidifying material raw material. To use waste gypsum board.   In the step (2), the regenerated hemihydrate gypsum is mixed with the gypsum board raw material, cement raw material, cement-based material obtained by mixing a part of the gypsum component constituting the waste gypsum board into a semi-water gypsum. The utilization method of the waste gypsum board of Claim 1 which is a process used as a solidification material raw material or a gypsum-type solidification material raw material.   In the step (3), the regenerated anhydrous gypsum is used as a cement raw material or a cement-based solidifying material raw material by mixing a part of the gypsum component constituting the waste gypsum board into a anhydrous gypsum. The utilization method of the waste gypsum board of Claim 1 which is a process. Furthermore, the utilization method of waste gypsum board of Claim 1 which uses flue gas desulfurization gypsum, chemical byproduct gypsum, natural dihydric gypsum, or natural anhydrous gypsum for at least 1 process of said (1)- (3) .

Images