JP4398308B2 - Waste gypsum board processing method - Google Patents

Description

  The present invention relates to a novel method for treating waste gypsum board. Specifically, the present invention provides a processing method capable of effectively using a large amount of waste gypsum board.

  The annual amount of waste gypsum board generated is about 1.5 million tons, of which about 500,000 tons are scraps from production and new interior construction work, which are recycled by gypsum board manufacturers. However, the remaining 1 million tons are discharged through renovation and dismantling work, and almost all of it is disposed of. The amount of waste gypsum board generated tends to increase year by year, and an effective treatment method for waste gypsum board is required from the viewpoint of lack of landfill and environmental conservation.

  Until now, as a processing method of waste gypsum board, a method of recovering gypsum by heat-treating waste gypsum board and carbonizing papers contained in the waste gypsum board has been proposed (see Patent Document 1). In addition, a method has been proposed in which waste gypsum board is heat treated to burn and remove papers and other organic components such as surfactant contained in the waste gypsum board (Patent Document 2). reference).

JP-A-6-142633 Japanese Patent Laid-Open No. 10-36149

  However, since the gypsum obtained by the above method is a gypsum that has become anhydrous by firing, in order to use it in large quantities as a gypsum for Portland cement having a large amount of production, an operation to convert to a two-water type is separately required. Necessary and problematic in industrial implementation.

  Moreover, when using it with an anhydrous form, the use was restrict | limited and it was difficult to ensure a large amount of usage.

  Therefore, as described above, no effective means has yet been found for a treatment method capable of sufficiently digesting a large amount of waste gypsum board, and it is desirable that an innovative treatment method be proposed. It was where

  The inventors of the present invention have made extensive studies to achieve the above object. As a result, the conventional concept of using waste gypsum board as gypsum was broken, and this was brought into contact with an aqueous alkali hydroxide solution typified by an aqueous sodium hydroxide solution, and the contained calcium content was recovered as a calcium hydroxide precipitate. By doing so, the use which can use this in large quantities was opened, it discovered that waste gypsum board could be digested in large quantities, and came to complete this invention.

  That is, this invention is a waste gypsum board processing method characterized by recovering the calcium content contained as a calcium hydroxide precipitate by bringing the waste gypsum board into contact with an aqueous alkali hydroxide solution.

  In addition, the calcium hydroxide precipitate obtained by the above method inevitably contains an organic component such as a surfactant, but it can be treated in large quantities in combination with a suitable process that can be used without any problem. is there.

That is, according to the present invention,
(1) A method for treating a waste gypsum board using the calcium hydroxide precipitate as an alkaline agent in a chlorohydrinization step and a saponification step,
And (2) A method for treating a waste gypsum board using the calcium hydroxide precipitate as an alkali source for producing a refuse solid fuel (RDF).

  That is, according to the treatment method of the present invention, the waste gypsum board is recovered as a calcium hydroxide precipitate, so that it can be used in a large amount unlike the conventional use of gypsum as a cement admixture. , Waste gypsum can be used, and a large amount of waste gypsum can be processed.

  In the present invention, the gypsum board waste material to be treated includes all of the gypsum board scraps in the above-described gypsum board production or new interior construction, gypsum board discharged in refurbishment and demolition work, and the like.

  In the present invention, the gypsum board waste material is preferably pulverized in order to efficiently react with the alkali hydroxide aqueous solution. The degree of crushing is generally about 0.1 to 2000 μm, preferably about 5 to 300 μm in average particle size.

  In the pulverization, it is preferable to remove the paper from the waste gypsum board because the efficiency of the pulverization can be increased and the amount of paper mixed into the calcium hydroxide precipitate obtained by the reaction can be reduced.

  As a method for removing the paper from the waste gypsum board, a known method is employed without any particular limitation. Specifically, as disclosed in Japanese Patent Application Laid-Open No. 10-286553, the gypsum board waste material is crushed and a relatively large paper is removed by combining a sieve of a predetermined mesh size. A method of removing paper by blowing and blowing away, as shown in Japanese Patent Laid-Open No. 2000-254531, passing gypsum board waste material through a roll-type breaker with ridges, crushing only the brittle gypsum base, And a method of removing paper by peeling gypsum from the surface.

  In removing the paper, the remaining amount of paper is preferably as small as possible, and is preferably 4% by weight or less, particularly 1% by weight or less in the gypsum.

  Moreover, the method of grind | pulverizing gypsum board waste material to the said particle diameter can be performed using a well-known grinder. For example, crushers such as compression crushers, shear crushers, impact crushers, etc., roll mills, hitting type crushers, high speed rotary impact crushers, ball mills, medium agitating crushers, jet crushers, wet high speed rotation A fine pulverizer such as a mill can be used.

  In the present invention, an industrially available alkali hydroxide aqueous solution is used without particular limitation. However, considering the reactivity with gypsum, the amount of supplied water used, the concentration of the produced alkali sulfate, etc. Those having a concentration of 1 to 50 wt%, particularly 5 to 15 wt% are preferred. Generally, it can be obtained by diluting an aqueous alkali hydroxide solution having a concentration of about 30 to 48 wt% with water. Of course, when there is an alkali hydroxide aqueous solution obtained as a waste, it is also possible to use it.

  The alkali hydroxide is typically sodium hydroxide or potassium hydroxide, but sodium hydroxide is particularly preferable.

  In the present invention, as a method for contacting the waste gypsum board crushed material with the alkali hydroxide aqueous solution, a mode in which a precipitate of calcium hydroxide is generated by a reaction between the gypsum and the alkali hydroxide is employed without any particular limitation.

  Specifically, a method of mixing in a reaction vessel equipped with a stirrer, a method of mixing using a mixer in a pipe, and a method of spraying a processing fluid from a nozzle with a high-pressure plunger pump and further striking the fixed plate. Examples thereof include a pressure nozzle type stirrer.

  Moreover, in the above-mentioned preferred alkali hydroxide concentration, the ratio of gypsum to alkali hydroxide is 1.0 to 1.5 times the chemical equivalent of alkali hydroxide to gypsum, preferably 1.0 It is preferable to set it as the ratio which becomes -1.1 times. Moreover, 10-40 degreeC is suitable for the temperature at the time of a contact. Furthermore, the pressure is preferably normal pressure.

  Although the said reaction time is based also on the density | concentration of an alkali hydroxide and the particle diameter of a ground material, 5 to 60 minutes are suitable, and produce | generate the precipitate of calcium hydroxide in the same reaction liquid.

  In the present invention, the method for recovering the generated calcium hydroxide precipitate is not particularly limited. The precipitate is an extremely fine precipitate having an average particle size of about 0.1 to 20 μm, and a separation method suitable for the precipitate is selected. That is, separation from the liquid phase part is usually performed by a rotary screen called a filter, a drum filter, a disk filter, a Nutsche filter, a filter press, a screw press, a tube press, or a screw decanter usually called a centrifuge, a screen. A method using a solid-liquid separator such as a decanter is preferred.

  Further, after filtration, it is preferable to wash the calcium hydroxide precipitate with water because the amount of the organic component adhering and the alkali sulfate produced by the reaction can be reduced. The allowable amount of the organic component and sodium sulfate varies depending on the process using the calcium hydroxide precipitate and cannot be generally limited. However, generally, the concentration of the organic component is 1 wt% or less, preferably 1000 ppm or less. In addition, it is preferable to carry out the above water washing so that the concentration of sulfate ions is 1 wt% or less, preferably 5000 ppm or less.

  The processing method of the waste gypsum board of this invention includes the aspect which uses the deposit of the calcium hydroxide collect | recovered by the method mentioned above in various uses.

  Specific examples of such an embodiment include the following embodiments.

(1) A mode in which the precipitate of calcium hydroxide is added as a saponifying agent to the saponification step of chlorohydrin,
(2) A mode in which the precipitate of calcium hydroxide is used as a raw material for producing refuse solid fuel (RDF),
(3) A mode in which the precipitate of calcium hydroxide is added as an alkaline agent to a waste incinerator,
(4) A mode of supplying the calcium hydroxide precipitate as a calcium source of the cement raw material to the cement manufacturing process,
(5) An embodiment in which the precipitate of calcium hydroxide is used as an alkali source and is supplied to the papermaking process.

  A typical embodiment among the use embodiments of the calcium precipitate will be described in detail.

(About the mode (1))
This embodiment relates to an embodiment of a method for treating waste gypsum used as an alkali agent in a chlorohydrinization step and a saponification step.

  And this aspect can be implemented by the following process which shows the outline in FIG.

  That is, from the above mixing step, a mixing step in which the waste gypsum board 1 pulverized in advance, the aqueous alkali hydroxide solution 2 and the water 3 are brought into contact with each other in the reaction mixing tank 4 to form a precipitate of calcium hydroxide and an alkali sulfate. The obtained slurry after reaction was separated into a calcium hydroxide precipitate 6 and an aqueous alkali sulfate solution 7 by a solid-liquid separator 5 and washed with washing water 8 and obtained from the separation step. In the repulp tank 9, the calcium hydroxide precipitate is used in the repulping process to make lime milk with the repulp water 10, and the obtained lime milk is used in the chlorohydrinization process, and further used in the saponification process of the generated chlorohydrin.

  First, the obtained lime milk is supplied to a chlorohydrination reaction apparatus in which chlorine 11, alkene 12 and water 13 are reacted, and the produced chlorohydrin aqueous solution is brought into contact with the obtained lime milk to saponify oxides 15. Steam 16 is used in apparatus 16 and removed from the top. This is a waste gypsum board treatment method comprising discharging waste water from the tower bottom and treating it in a waste water treatment process.

  The method of using the calcium hydroxide precipitate for the saponification reaction of chlorohydrin not only makes the reaction less susceptible to the organic components brought in by the calcium hydroxide precipitate, but also shares wastewater treatment facilities. It is possible.

  That is, the obtained oxides 15 are separated by the saponification reaction apparatus 16 with the steam 17, and the waste water 18 discharged from the bottom of the tower is rendered harmless by the processing equipment.

  In this embodiment, a known method can be employed without particular limitation as a method of using a calcium hydroxide precipitate as an alkaline agent in the chlorohydrinization step and the saponification step.

(About the mode (2))
This embodiment relates to an embodiment used as a raw material for producing solid refuse fuel (RDF).

  This embodiment can be implemented by the following steps, the outline of which is shown in FIGS.

  That is, the process shown in FIG. 1 is performed until a calcium hydroxide precipitate is obtained. The subsequent production of solid waste fuel (RDF) is performed in the process shown in FIG. That is, combustible waste 19 is crushed with a crusher 20 and adjusted or adjusted with the calcium hydroxide precipitate 6, the alkali agent 21 such as quicklime and the adjustment tank 22. The precipitate and an alkaline agent such as quicklime are mixed with a mixer 23 and blended in a curing tank 24. Thereafter, the pellet is molded by the compression molding machine 25 and dried in the drying chamber 26 to obtain a solid waste fuel (RDF) 27.

  The solid waste fuel (RDF) thus obtained can be treated without problems in organic matter contained in the calcium hydroxide precipitate by burning in an incinerator or a combustion furnace.

(Regarding usage of alkali sulfate produced as a by-product)
On the other hand, wastewater containing alkali sulfate, which is the liquid phase part after separation of calcium hydroxide precipitates, can be brought into contact with calcium chloride to produce high-purity gypsum with an extremely low organic content. is there. The gypsum can be used for various uses such as high-purity dental gypsum, gypsum for producing cement by adding to cement clinker, and further as a reagent.

  It is also possible to concentrate the waste water containing the alkali sulfate to crystallize the alkali sulfate and recover it as a high-purity alkali sulfate. In this case, the concentration can be performed with a known apparatus and conditions.

  Furthermore, in the embodiment of (1), the calcium chloride contained in the effluent obtained from the saponification step of chlorohydrin and the alkali sulfate can be reacted to produce gypsum, which can be carried out without any particular limitation. it can. The obtained gypsum becomes extremely pure gypsum by washing with water. The gypsum can be used for the same applications as the high-purity gypsum.

Example 1
Waste gypsum board 50.6 kg / h, 48% caustic soda 49.0 kg / h, and water 150 kg / h were mixed in a mixing reaction tank with a residence time of 30 minutes to obtain a calcium hydroxide precipitate and sodium sulfate slurry. . Using the resulting slurry, a calcium hydroxide precipitate cake was obtained at 48.9 kg / h using a solid-liquid separator. At this time, the cake was washed with 50 kg / h of water.

  The washed calcium hydroxide precipitate was repulped in a repulp tank by adding 32.0 kg / h of water to obtain 80.9 kg / h of lime milk having a CaO concentration of 20%. As a result of analysis of the obtained lime milk, the sulfate ion concentration in the lime milk was 500 ppm.

  10.0 kg / h of the obtained lime milk was supplied to a chlorohydrin reactor containing 3.0 Nm3 / h of chlorine, 3.3 Nm3 / h of propylene and 250 kg / h of water to synthesize a chlorohydrin aqueous solution. The temperature was raised to 95 ° C. and 28.1 kg / h of the obtained lime milk was supplied to carry out the saponification reaction. In the saponification reaction apparatus, 7.3 kg of propylene oxide from the top of the tower at a steam of 23.8 kg / h. / H. Moreover, after draining 290.6kg / h of waste water from the tower bottom, it was discharged after processing within the discharge standard in the waste water treatment process.

  As described above, the calcium hydroxide precipitate obtained by the method of the present invention could be used without any problem in the production process of propylene oxide.

  And it became possible to expand the use of waste gypsum.

Process drawing which shows suitable embodiment of the chlorohydrin process of the method of this invention, and a saponification process Process drawing which shows suitable embodiment of the refuse solid fuel of the method of this invention

Explanation of symbols

1: Waste gypsum board 2: Caustic soda 3: Water 4: Reaction mixing tank 5: Solid-liquid separator 6: Calcium hydroxide (slaked lime)
7: Sodium sulfate aqueous solution 8: Wash water 9: Repulp tank 10: Repulp water 11: Chlorine 12: Alkene 13: Water 14: Chlorhydrination reactor 15: Oxides 16: Saponification reactor 17: Steam 18: Drainage 19: Combustible waste 20: Crusher 21: Alkaline agent, etc. 22: Adjustment tank 23: Mixer 24: Curing tank 25: Compression molding machine 26: Drying chamber 27: Waste solid fuel (RDF)

Claims (2)

By contacting the waste gypsum board with an aqueous alkali hydroxide solution, the contained calcium content is recovered as calcium hydroxide precipitates, and the recovered calcium hydroxide precipitates are converted into chlorohydrin and saponification steps. A method for treating waste gypsum board, characterized by being used as an alkaline agent . By contacting the waste gypsum board with an aqueous alkali hydroxide solution, the contained calcium content is recovered as a calcium hydroxide precipitate, and the recovered calcium hydroxide precipitate is recovered as a solid waste fuel (RDF; Refuse). A method for treating waste gypsum board, characterized in that it is used as a raw material for producing Delivered Fuel) .

Images