JP2008264627A - Waste treatment material and treatment method for detoxifying fly ash (soot and dust) and burned ash or the like - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive inorganic compound powder treatment material for fly ash and burned ash containing harmful heavy metals discharged from incineration facilities, for not producing a harmful odor gas or preventing a treatment object from being decomposed by microorganisms even when reclaimed for a long period of time in a landfill site. <P>SOLUTION: Aluminum sulfate electrolysis waste liquid discharged from an aluminum product processing plant is reused to manufacture water insoluble basic aluminum sulfate, and it is mixed and kneaded with the fly ash and the burned ash together with water without being mixed with other inorganic compounds or the like as a single product. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention renders fly ash (dust) and incineration ash containing hazardous heavy metals (lead, cadmium, copper, zinc, chromium, etc.) discharged from incineration facilities of industrial waste and municipal waste harmless (non-eluting) The present invention relates to a waste treatment chemical and a detoxification treatment method.

Organic liquid chelating agents are generally used as agents capable of detoxifying (non-eluting) fly ash (dust) containing hazardous heavy metals discharged from industrial waste and municipal waste incineration facilities. (Patent Documents 1, 2 and 3) However, organic liquid chelates are mixed with kneaded fly ash and incinerated ash, kneaded and processed, and carbon disulfide (chemical formula: CS ₂ ) and hydrogen sulfide (chemical formula) are harmful to the human body. : H ₂ S), ammonia (chemical formula: NH ₃ ), amines (chemical formula: R—NH ₂ ) and other odorous component gases are generated. Also, it is dangerous because harmful odor component gas is generated during storage. Therefore, the equipment cost becomes expensive, for example, a safety device such as a ventilation facility must be provided.

  In addition, processed ash that has been rendered harmless (non-eluting) with organic liquid chelating agents is transported to a landfill site and landfilled.

  Detoxified (non-eluting) fly ash and incineration ash by organic liquid chelating agents are decomposed by microorganisms and fungi in anoxic (anaerobic) condition after being landfilled for a long time at a landfill site. The harmful heavy metals contained in the non-eluting treatment product are re-eluted.

  The present invention provides a treatment method that does not generate odorous component gas harmful to human body with an inorganic powder waste treatment material or that is not decomposed by microorganisms or fungi even if it is landfilled for a long time in a landfill site.

  Peripheral techniques of the present invention include powdered aluminum silicate or powdered silicon dioxide (see Patent Document 4) or X-ray amorphous aluminum hydroxide in an amount of 20% to 95% by weight and powdery porous material. Inorganic adsorbent and / or water-soluble phosphate 5 wt% or more and 80 wt% or less, and said X-ray amorphous aluminum hydroxide and powdery porous inorganic adsorbent and / or Examples include waste treatment agents with a total amount of water-soluble phosphate of 50% by weight or more (see Patent Document 5). In any case, several types of raw materials must be mixed with inorganic powder waste treatment agents. There are problems such as limited applications.

In addition, water, sulfuric acid bands (chemical formula: Al ₂ (SO ₄ ) ₃ ) and phosphate heavy metal fixing agents are used to convert alkaline heavy metal-containing ash into insoluble harmful metal compounds such as lead phosphate and cadmium phosphate. Proposed waste treatment agent and treatment method (Patent Document 6)
However, the objects to be detoxified by the present invention are fixed to sulfuric acid bands and phosphate heavy metals with fly ash (dust) and incineration ash discharged from incineration facilities such as industrial waste and municipal waste (household waste). The decrease in hydrogen ion concentration (pH) using strong acidic substances such as chemicals has a strong buffering action such as unreacted slaked lime (chemical formula: Ca (OH) ₂ ) contained in a large amount in fly ash. There was a problem that the added amount of sulfuric acid band and the like was extremely increased, the moldability of the processed product after processing was deteriorated, and the processing cost was increased. Furthermore, the sulfuric acid band has high hygroscopicity, and has many problems such as solidification and progress of corrosion in the storage tank.
JP-A-5-50055 JP-A-8-224560 JP-A-8-41017 Japanese Patent No. 3633010 Japanese Patent No. 3742602 JP-A-9-141226

  Industrial waste and municipal waste (household waste) are incinerated and fly ash (dust) and incinerated ash contain a lot of toxic heavy metals, which are detoxified (non-eluting) by some method. Then, it is taken out to landfill and disposed of. Conventionally, an organic liquid chelating agent such as diethyldithiocarbamate disclosed in Patent Documents 1 to 3 is often used and detoxified.

  These organic liquid chelating agents generate odorous component gases that are harmful to the human body, and there are problems such as decomposition of organic components by microorganisms and fungi and re-elution of toxic metals after landfill disposal.

  In addition, waste treatment agents in the form of inorganic powders such as aluminum silicate and silicon dioxide proposed in Patent Documents 4 to 5 have low neutralization performance as solid acids and low performance as adsorbents. As a result, there is a problem that the disposal amount after disposal increases and the disposal life of the landfill site is shortened.

The waste treatment agent used in the mixture of X-ray amorphous aluminum hydroxide and powdered porous inorganic adsorbent or water-soluble phosphate shown in Patent Document 5 is an alumite treatment step. It has been proposed to use the generated amorphous aluminum hydroxide. The waste treatment agent in the mixture of amorphous aluminum hydroxide, porous inorganic adsorbent or water-soluble phosphate is unreacted calcium hydroxide (chemical formula: To react with Ca (OH) ₂ ) to lower the hydrogen ion concentration (pH) in the eluate from fly ash and to make toxic heavy metals non-eluting, porous inorganic adsorbents or strong acid buffering A strong water-soluble phosphate must be mixed in amorphous aluminum hydroxide, and the manufacturing cost of the waste treatment agent becomes high, and there are problems such as lack of quality stability depending on the mixed material .

  Waste treatment agents using sulfate bands and phosphate heavy metal fixing agents proposed in Patent Document 6 are strong acid treatment agents that corrode facilities that mix and knead with fly ash. There are challenges.

    The present invention does not generate odorous gas components harmful to the human body from fly ash (dust) and incineration ash discharged from incineration facilities such as industrial waste and municipal waste (household waste), or the treated material is microorganisms in a landfill site And decomposed by fungi. Alternatively, an object of the present invention is to provide an inexpensive waste treatment agent and a treatment method which are not mixed with other compounds and are not corrosive at all.

Since the fly ash (industry) and incinerated ash of the present invention are rendered harmless (non-eluting), the waste treatment agent and the treatment method do not generate harmful odor gas components or the like, or neutralize with an acidic substance of an inorganic compound mixture Using water-insoluble basic aluminum sulfate, which is a single component of an inorganic compound that is not a major chemical reaction, and neutral, water ash and incineration ash are mixed and kneaded with water to detoxify it. Features.

  In the present invention, a sodium hydroxide solution is added to an aluminum sulfate solution in an electrolytic solution using sulfuric acid discharged from an aluminum product processing factory to adjust the hydrogen ion concentration (pH) to 4 to 8, and the resulting precipitate is washed with water. The water-insoluble basic aluminum sulfate produced by dehydration and drying was used alone as a waste treatment material without being mixed with other compounds, thereby solving the problem.

  Add waste treatment materials that make harmless (non-eluting) waste ash (dust) and incineration ash discharged from incineration facilities such as industrial waste and municipal waste (household waste) of the present invention, and mix The use of aluminum sulfate electrolytic solution in the aluminum product processing plant has expanded the use of aluminum sulfate electrolytic solution, and it is manufactured using aluminum sulfate waste liquid as a raw material, so it can be commercialized at an extremely low price compared to other waste treatment agents. It is stable without being decomposed into fine substances and bacteria after landfill disposal without generating possible harmful odor gas, and greatly contributes to environmental conservation.

Hereinafter, the present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited thereto. Slaked lime generated from municipal waste incineration facility (continuous operation of gasification solution furnace) to compare the detoxification (non-eluting) treatment effect of the waste treatment material of the present invention and the performance of materials exemplified in the patent literature (Chemical formula: Ca (OH) ₂ ) After blowing, fly ash (dust) collected by a bag filter type dust collector was used as a test sample. Select lead (Pb) as a representative item from the toxic heavy metals contained in fly ash samples, and prepare a test solution by the dissolution test method described in the Environmental Agency Notification No.13 Then, an analytical test was performed with an atomic absorption photometer, and various test evaluations were obtained using the landfill reference value (Pb = 0.3 mg / l).

  Using an aluminum sulfate waste solution discharged from an electrolytic solution of sulfuric acid used in an alumite surface treatment process of an aluminum product processing factory, an aqueous solution of sodium hydroxide (20 weight percent) in the aluminum sulfate waste solution (pH is about 2.8), Add, adjust the hydrogen ion concentration (pH) to the range of 4.0 to 13.0 to produce a precipitate, collect it, dry it after washing with water, and use it as a waste treatment material of the present invention. Powders prepared by adjusting the pH from 4 to 8 are classified and displayed in 5 conditions of treatment materials 4 to 8, and powder samples manufactured by adjusting the pH from 9 to 13 are shown in 5 of Comparative Examples 1 to 5. The conditions are shown in Table 1. Table 1 shows the performance evaluation as a waste treatment agent by producing water-insoluble basic aluminum sulfate as a waste treatment agent after drying.

  In the performance evaluation test, the hydrogen ion concentration was adjusted to the fly ash sample.

  The waste treatment material was added at 8 and 10 percent by weight with respect to the fly ash sample, respectively, and similarly 40 percent by weight of water was added and mixed and kneaded to obtain a sample for performance evaluation.

As is apparent from Table 1, the pH adjustment range for producing a water-insoluble basic aluminum sulfate waste treatment material from an aluminum sulfate waste liquid is suitably 4 to 8, and if it exceeds 8, it is amorphous in X-rays However, the amount of aluminum hydroxide (chemical formula: Al (OH) ₃ ) increases as much as possible, the content of sulfate groups (chemical formula SO ₄ ) becomes extremely small, and the performance of non-eluting lead (Pb) decreases. .

In the present invention, the hydrogen ion concentration (pH) adjustment range in the production of the water-insoluble basic aluminum sulfate waste treatment material by adding sodium hydroxide from the aluminum sulfate waste solution discharged from the anodized surface treatment step is suitably 4-8. However, it is most desirable to use a waste treatment material manufactured in the range of pH = 6-8.

      In order to evaluate the performance of the waste treatment material of the present invention, the product processed to recycle the aluminum sulfate electrolysis waste liquid discharged from the alumite treatment process of the actual aluminum product processing factory, and the porous inorganic powder adsorption It has been proposed as a raw material for chemicals or waste treatment materials. A test for detoxification (non-eluting) treatment effect was conducted using an inorganic compound as a comparative example.

      In the test, the waste treatment material of the present invention and other treatment materials or treatment material raw materials were each measured by weight ratio with respect to the fly ash sample used in Example 1 to confirm the detoxification treatment effect. 8, 10, 12, 14% was added, and after mixing and kneading, an elution test was conducted by the Environmental Agency Notification No. 13 method, and lead (Pb) was measured by atomic absorption spectrophotometry.

  Table 2 shows the details of the treated materials and raw materials used in the test.

  Table 3 shows the test results on the detoxification (non-eluting) treatment effect of the waste treatment material and other materials of the present invention described in Table 2.

   As seen in Table 3, it can be confirmed that the water-insoluble basic aluminum sulfate, which is the waste treatment material of the present invention, and the compound form are the same, and commercially available alumina white or the like acts effectively. In addition, although commercially available aluminum sulfate is also recognized as detoxifying, it is difficult to commercialize due to problems such as hygroscopicity in the storage tank and corrosion of equipment due to strong acidity.

In Table 3, the materials and compounds for which the effect of detoxification treatment could be confirmed all contain sulfuric acid (SO ₄ ) groups and play an important role in the waste treatment material of the present invention. It is clear that it is indispensable.

Claims (7)

Aluminum hydroxide (chemical formula is Al) as a treatment material for detoxifying (non-eluting) fly ash (dust) containing hazardous heavy metals discharged from incineration facilities for industrial waste or municipal waste (household waste) (OH) ₃ ), not aluminum sulfate (chemical formula: Al ₂ (SO ₄ ) 3), water-insoluble basic aluminum sulfate, and chemical formula Al ₂ (SO ₄ ) (OH) ₄ Or waste treatment material indicated by Al ₄ (OH) SO ₄ The water-insoluble basic aluminum sulfate of the preceding item 1 has a composition ratio in which the composition percentage is converted with aluminum oxide (chemical formula Al ₂ O ₃ ) and is more than twice the composition weight percent of sulfuric acid (chemical formula SO ₄ ). When converted as SO ₄ ), the composition ratio of sulfuric acid is 10% by weight or more.   90% by weight or more of the water-insoluble basic aluminum sulfate of the preceding paragraphs 1 and 2 is a strong acid having an amorphous substance (amorphous) powder form, insoluble in water, hot water, hot water, etc. and having a hydrogen ion concentration (pH) of 2 or less. Waste material that dissolves quickly in a basic solution or a strongly basic (alkaline) solution having a hydrogen ion concentration (pH) of 12 or more The water-insoluble basic aluminum sulfate of 1 to 3 above can be used as a similar chemical product that is generally manufactured and sold as a chemical industrial chemical, but anodization by electrolysis performed in an aluminum product processing factory. Select sulfuric acid from the sulfuric acid, chromic acid, and oxalic acid used in the coating treatment, and heat the discharged aluminum sulfate (chemical formula is Al ₂ (SO ₄ ) ₃ ) at 50 ° C or higher for 24 hours or longer The precipitate obtained by the treatment is subjected to solid-liquid separation using a furnace or a centrifugal separator, and the precipitate is washed with water, and is continuously performed until the hydrogen ion concentration (pH) of the washing liquid becomes 4 or more. The washed precipitate is pulverized after drying using a spray dryer or kiln-type drying device, or air separation, etc., and the powder state is a fine particle size with a mean particle size (D50) of 50um or less as measured by a dry laser particle size analyzer. Waste treatment material in powder form While stirring the aluminum sulfate (chemical formula is Al ₂ (SO ₄ ) ₃ ) solution discharged in the preceding item 4, 5 to 40 weight percent sodium hydroxide solution is added, and the hydrogen ion concentration of the strongly acidic solution of the aluminum sulfate solution ( pH) is adjusted to the range of 4-8, the resulting precipitate is washed with water, and the waste treatment material using fine powder after drying by the method of the previous item 4 To make fly ash (dust) containing hazardous heavy metals discharged from incineration facilities of industrial waste or municipal waste (household waste) detoxified (non-eluting) using the waste treatment material of claims 1 to 5 Is performed using the fly ash treatment equipment or incineration ash treatment equipment in each incineration facility, and the amount of waste treatment material selected at a rate of 1 to 50 weight percent with respect to fly ash (dust) Waste treatment method in which a selected amount of water is added at a ratio of 10 to 50 weight percent with respect to fly ash, and the treated product is discharged after mixing and kneading are sufficiently performed Calcium hydroxide (chemical formula = Ca (OH) ₂ ) used as an exhaust gas purifying agent in an incineration facility for industrial waste or municipal waste (household waste) using the waste treatment material of claims 1 to 6 It can be used by mixing with activated carbon. Calcium hydroxide has limited application due to the size of the specific surface area, etc., but the waste treatment material according to claims 1 to 6 can be used by mixing regardless of the size of the specific surface area. It is used by mixing in the range of 1 to 50 weight percent with respect to calcium oxide. Activated carbon can be used by mixing in the range of 0.5 to 20 weight percent with respect to calcium hydroxide. A mixture of the waste treatment material of claim 1 to 6 and calcium hydroxide or waste treatment material, calcium hydroxide and activated carbon is used as an exhaust gas purifier from a calcium hydroxide storage tank in an incineration facility or a pollutant gas concentration ( In general, hydrogen chloride gas, sulfuric acid gas, nitric acid gas, etc., which are cut out according to the hydrogen chloride gas) and collected in dust collectors such as electrostatic precipitators and bag filter type dust collectors are blown into the flue Calcium hydroxide is used to purify the exhaust gas, and fly ash is treated with the waste treatment material of claims 1 to 5 for detoxification, and exhaust gas purification and detoxification (non-elution) treatment for harmful heavy metals are performed simultaneously. Waste treatment materials and treatment methods