JP2009006206A - Treatment method of solidified slag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treatment method of solidified slag which inexpensively stabilizes the pH of the bled-out water from the solidified slag within the range of 5.8-8.6 of a quality standard of water in a short time by a simple treatment requiring no special apparatus. <P>SOLUTION: In the treatment method of the solidified slag for stabilizing the pH of the bled-out water from the solidified slag obtained by solidifying molten slag originating from waste, the solidified slag and an inorganic acidic chemical agent are mixed in such a ratio that the inorganic acidic chemical agent of 0.005 pts.mass or more is contained based on the solified slag of 100 pts.mass. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for treating a slag solidified product, more specifically, a slag solidified product which stabilizes the pH of leachate from a slag solidified product obtained by solidifying molten slag derived from waste to a water quality standard of 5.8 to 8.6. It relates to the processing method. When incineration residues of waste such as municipal waste and industrial waste are processed in a melting furnace, and when such waste is processed in a gasification melting furnace, the generated molten slag is discharged from these melting furnaces. The discharged molten slag is solidified by water cooling or air cooling to become a slag solidified product. Most of the slag solidified materials are disposed of in landfills, but some of them are used as aggregates for civil engineering works, aggregates for secondary concrete products, etc. as substitutes for natural aggregates.

  By the way, when landfilling the slag solidified material as described above, the structure standard, maintenance management standard and abolition standard of the landfill site are stipulated in the standard ministerial ordinance revised on June 16, 1998. In this abolition standard, a standard for abandoning a landfill site as a stable disposal site is defined, and for leachate, the pH is determined to be 5.8 to 8.6 of the water quality standard. The present invention relates to a method for treating a slag solidified product that stabilizes the pH of leachate from the slag solidified product within a range of 5.8 to 8.6 based on water quality.

  Conventionally, as a treatment method for stabilizing incineration fly ash and molten fly ash, a method of mixing these with an organic chemical, usually various chelating agents, is known. However, when trying to apply this to a treatment method that stabilizes slag solidified products, such organic chemicals have problems in sustaining effects, and are liable to generate harmful gases and bad odors due to decomposition, so that they can be effectively used. There is a problem of becoming an obstacle. Therefore, conventionally, instead of organic chemicals, inorganic chemicals are used as a treatment method to stabilize the slag solidified product, and the molten slag discharged from the melting furnace is dispersed in a water granulating tank or a subsequent water washing tank. There has been proposed a method in which an agent and a flocculant are added, and a slag solidified product obtained by pulverization and solidification is washed with a dispersant and / or agglomerated with a flocculant (for example, see Patent Document 1). As another treatment method, in the step of magnetically separating and crushing the slag solidified product with a special apparatus, an alkali such as lime and water is added before or after such treatment, heated and cured for a certain time, for example, A method of curing at 60 to 100 ° C. for 0.1 to 2 hours has also been proposed (see, for example, Patent Document 2).

However, since the dispersing agent and the flocculant are added to the granulating tank and the washing tank in the method for treating a slag solidified product as described in Patent Document 1, the amount of these chemicals used is increased and the chemicals are added. In addition, there is a problem in that the cost increases because the water treatment equipment for the water from the granulated tank and the washing tank is loaded. Moreover, since the processing method of slag solidified material like the above-mentioned patent document 2 requires a special apparatus and actually requires curing, there is a problem that the apparatus and processing are expensive and time consuming. is there.
JP 2000-263015 A JP 2003-145123 A

  The problem to be solved by the present invention is that the pH of leachate from the slag solidified product is within a range of 5.8 to 8.6 based on water quality in a simple and inexpensive process that does not require a special device. It is in the place which provides the processing method of the slag solidified material which can be stabilized inside.

  The present invention for solving the above-mentioned problems is a method for treating a slag solidified product that stabilizes the pH of leachate from a slag solidified product obtained by solidifying molten slag derived from waste, which comprises a slag solidified product and an inorganic acidic agent. Are combined at a ratio of 0.005 parts by mass or more of the inorganic acidic agent per 100 parts by mass of the slag solidified product.

  Even in the processing method for solidified slag according to the present invention (hereinafter simply referred to as the processing method of the present invention), the object to be processed is the solidified slag. As described above, when incineration residues of waste such as municipal waste and industrial waste are processed in a melting furnace, and when such waste is processed in a gasification melting furnace, the generated molten slag is discharged from these melting furnaces. The The discharged molten slag is solidified by water cooling or air cooling to become a slag solidified product. In the treatment method of the present invention, the slag solidified product is treated.

  In the treatment method of the present invention, the slag solidified material as described above is mixed with an inorganic acidic drug, and preferably further mixed with a lime based drug. In the case of using a liquid material, such as an aqueous liquid, as the inorganic acidic drug or lime based drug, it can be mixed with the slag solidified product as it is. Are used, it is preferable to adjust the water content of the slag solidified product to 5 to 15% by mass in advance so that they adhere to the surface of the slag solidified product sufficiently uniformly, and 6 to 10% by mass. It is more preferable to adjust it. The temperature of the slag solidified product at the time of mixing is not particularly limited as long as it is clearly not from the slag solidified product and the water immediately evaporates, but generally it may be a so-called normal temperature, for example, 20 to 80 ° C.

  In the treatment method of the present invention, examples of the inorganic acidic chemicals include inorganic and acidic phosphate chemicals, iron chloride chemicals, aluminum sulfate chemicals, aluminum chloride chemicals, and the like. In addition to phosphoric acid, primary sodium phosphate, primary potassium phosphate, secondary sodium phosphate, secondary potassium phosphate, calcium phosphate, magnesium phosphate, etc. Drugs. In addition to ferrous chloride, ferric chloride and the like, examples of the iron chloride-based drug include drugs mainly composed of these. In addition to the sulfate band, examples of the aluminum sulfate-based drug include drugs based on this, and examples of the aluminum chloride-based drug include drugs based on this in addition to polyaluminum chloride. Among them, the inorganic acidic agent is preferably one or two or more selected from phosphoric acid, ferric chloride, sulfuric acid band and polyaluminum chloride, which may be liquid or solid. However, a liquid material is preferable.

  In the treatment method of the present invention, examples of the lime-based drug include slaked lime, quick lime, calcium carbonate, calcium hydrogen carbonate, and the like, and a drug mainly composed of these. Of these, slaked lime is preferable.

  When the slag solidified product is obtained by granulating the molten slag discharged from the melting furnace, the slag solidified product is generally pulled up from the granulation tank → conveying → magnetic separation → conveying → crushing → conveying → storage process. Has been processed. In addition, when the slag solidified product is obtained by solidifying the molten slag discharged from the melting furnace by air cooling, the slag solidified product is generally transported from the air cooling device → primary crushing → classification → conveying → secondary crushing → classifying → conveying. → It is processed in the storage process. In such a slag solidified material processing step, crushing in the sense including primary crushing and secondary crushing is referred to as various types of crushers, crushers, grinders, etc., such as high-speed centrifugal grinders and cage mills. Although these are used, all of them are designed to crush the slag solidified product with vigorous stirring.

  Therefore, in order to adhere the inorganic acidic agent and further the lime-based agent to the surface of the slag solidified material sufficiently uniformly, the slag solidified material as described above is meant to include primary crushing and secondary crushing here. In the crushing step, it is preferable to add and mix an inorganic acidic drug or further a lime-based drug immediately before, during and / or after crushing. In particular, when the slag solidified product is obtained by granulating and solidifying the molten slag discharged from the melting furnace, in the step of magnetically selecting the slag solidified product as described above and further crushing, after the magnetic separation and It is more preferable to add and mix an inorganic acidic drug or even a lime chemical before and / or during crushing. When the slag solidified product is obtained by solidifying the molten slag discharged from the melting furnace by air cooling, the slag solidified product is subjected to primary crushing and further secondary crushing as described above. In addition, it is preferable to add and mix an inorganic acidic drug or further a lime based drug before and / or during the secondary crushing.

  In the treatment method of the present invention, the inorganic acidic drug can be used alone, but is preferably used in combination with the lime based drug. These amounts to be mixed with the slag solidified product are such that the amount of the inorganic acidic drug is 0.005 parts by mass or more per 100 parts by mass of the slag solidified product in terms of dry matter, and the lime based drug is 0.003 parts by mass or more. However, it is preferable that the amount of the inorganic acidic drug is 0.005 to 5 parts by mass and the amount of the lime based drug is 0.003 to 1 part by mass.

  According to the treatment method of the present invention, the pH of the leachate from the slag solidified product is within the range of 5.8 to 8.6 of the water quality standard in a simple and inexpensive manner that does not require a special apparatus and in a short time. Can be stabilized.

When the incineration residue of municipal waste is treated in an arc melting furnace, the molten slag discharged from the arc melting furnace is crushed and solidified, and the crushed and solidified slag is pulled up from the granulating tank → conveyed → It processed in the process of magnetic separation->conveyance->crushing->conveyance-> storage, and air-dried. 100g of air-dried slag solidified product is placed in a wide-mouthed plastic container with a lid, added with inorganic acidic chemicals and further lime based chemicals listed in Table 1, shaken up and down for 10 minutes, and then allowed to stand at room temperature for 150 hours did. After adding 500 ml of purified water to a wide-mouthed plastic container and shaking up and down for 15 seconds, the solution was separated and the pH was measured. The results are shown in Table 1. In addition, the comparative example 1 is an example (blank) which does not add an inorganic acidic chemical | medical agent and a lime based chemical | medical agent. Moreover, the addition amount of the aqueous solution of phosphoric acid or ferric chloride is the addition amount as an aqueous solution.

  As is clear from the results of Table 1, in each example, the pH of the leachate from the slag solidified product can be stabilized within the range of 5.8 to 8.6 of the water quality standard. .

Claims (5)

  A method for treating a slag solidified product that stabilizes the pH of leachate from a slag solidified product obtained by solidifying a molten slag derived from waste, the slag solidified product and an inorganic acidic chemical agent per 100 parts by mass of the slag solidified product The processing method of the solidified slag characterized by mixing in the ratio from which an inorganic acidic chemical | medical agent will be 0.005 mass part or more.   Furthermore, the processing method of the slag solidified material of Claim 1 which mixes a lime based chemical | medical agent in the ratio from which a lime based chemical | medical agent becomes 0.003 mass part or more per 100 mass parts of slag solidified material.   Slag solidified product, inorganic acidic drug and lime based drug, ratio of 0.005 to 5 parts by mass of inorganic acidic drug and 0.003 to 1 part by mass of lime based drug per 100 parts by mass of slag solidified product The processing method of the slag solidified material of Claim 2 mixed by.   The method for treating a solidified slag according to any one of claims 1 to 3, wherein the inorganic acidic agent is one or more selected from phosphoric acid, ferric chloride, a sulfate band, and polyaluminum chloride. .   The method for treating a solidified slag according to any one of claims 2 to 4, wherein the lime-based drug is slaked lime.