TW201912209A - Method for stabilizing MSWI fly ash - Google Patents

Abstract

A method for stabilizing municipal solid waste incinerator (MSWI) fly ash includes a step of preparation, a step of water washing, a step of filter pressing and a step of mixing. The step of preparation is to prepare MSWI fly ash containing 10 to 75 percent by weight CaO. The step of water washing is to subject the MSWI fly ash to a water-washing treatment with a designated liquid/solid ratio to remove water-soluble salt and reduce the content of heavy metals. The step of filter pressing is to press and dehydrate the MSWI fly ash with a filter press so that MSWI fly ash becomes flattened. The step of mixing is to mix the flattened MSWI fly ash with an agent which is a strong base and stirring in order that the agent reacts with the MSWI fly ash during the stirring process to obtain a reaction temperature ranging from 35 DEG C to 80 DEG C which helps a reduction in the leaching of heavy metals. Therefore, the effect of stabilization for MSWI fly ash can be obtained, and the stabilized MSWI fly ash can be recycled and reused.

Description

Stabilization method for incineration fly ash of garbage power plant

The invention relates to a waste incineration fly ash treatment method, in particular to a garbage power plant incineration fly ash stabilization method.

After investigation, the combustible waste is collected and transferred to an incineration power plant for incineration treatment, which is burned into bottom slag to achieve the effect of waste reduction and volume reduction. Incineration waste gas containing fly ash is generated during the incineration process. After a dust collecting device separates the exhaust gas from the fly ash, and collects the fly ash, the fly ash is a hazardous business waste, so in order to reduce the pollution of the substance, to avoid the release of harmful substances in the fly ash, usually After solidification and stabilization through cement, the solidified fly ash and the bottom slag of general business waste are transported to a general landfill for landfill or stacking. However, due to the large amount of fly ash, even if it has a large land area, it will one day still face the dilemma of insufficient land. If Taiwan is the case, there is a problem of insufficient flat area, which can be used for the bottom slag and fly. The ash burial site is much less, and the volume of the bottom slag and fly ash after solidification is increased, so that the volume that can be accommodated in the landfill is reduced. Therefore, if the ash is only disposed of by solidification or burial alone. In other words, it is no longer able to cope with the existing demand. Moreover, the fly ash generated by incineration of wastes is increasingly being taken seriously by the public for the harmful effects of harmful substances on human health and the living environment. How to adopt appropriate methods and steps? It is an urgent task to dispose of the fly ash to achieve the goal of stability, harmlessness and resource utilization.

Therefore, the object of the present invention is to provide a method for stabilizing fly ash in a waste power plant, which can reduce the water-soluble salt of the fly ash and reduce the dissolution rate of the heavy metal, thereby achieving a stabilizing effect, and causing the stabilized waste power plant to incinerate fly ash. We can use resources again.

Therefore, the method for stabilizing the incineration fly ash of the garbage power plant of the present invention comprises a preparation step, a water washing step, a pressure filtration step and a mixing step, wherein the preparation step comprises preparing a waste containing 10 to 75% by weight of calcium oxide. The power plant incinerates the fly ash (ie, the preparation step); in addition, the water washing step washes the incineration fly ash and water of the garbage power plant at a liquid-solid weight ratio of 1:2 to 1:20 to remove the water-soluble incineration fly ash of the garbage power plant. After the salt is used, the pressure filtration step is further carried out by a filter press to incinerate the fly ash into a water content of 5 to 60% mud cake; finally, a pH value of 12 to 15.6 is prepared. The hydroxide ion has a molar concentration of 0.01M~37.5M, and the incineration fly ash of the waste cake-like waste power plant is mixed with the agent at a liquid-solid weight ratio of 0.2~1.5, so that the mixing process is performed. The agent is heated in response to the incineration fly ash of the garbage power plant, so that the salt in the incineration fly ash of the garbage power plant and the agent are reduced by the reaction, thereby stabilizing the effect, and incinerating the waste power plant with stable properties. Fly ash can again Line utilization of resources.

The above and other technical features, features, and advantages of the present invention will become apparent from the Detailed Description of the <RTIgt;

Referring to FIG. 1 , a method for stabilizing fly ash in a garbage power plant according to the present invention comprises a preparation step, a water washing step, a pressure filtration step and a mixing step; wherein the preparation step comprises preparing a waste containing 10 to 75% by weight of calcium oxide. The power plant incinerates the fly ash, and the incineration fly ash of the waste power plant may be an incineration fly ash of a mechanical hearth incinerator or a plant incineration fly ash of a fluidized bed incinerator, and the foregoing grate furnace waste power plant incinerates and flies. The elemental composition of ash: calcium oxide (CaO) is 20~75% by weight; alumina (Al ₂ O ₃ ) is 0~30% by weight; cerium oxide (SiO ₂ ) is 0~30% by weight The content of harmful heavy metal elements is 300~10000 ppm; in addition, the elemental composition of the incineration fly ash of the fluidized bed grate furnace waste water power plant: calcium oxide (CaO) is 10~50% by weight; alumina (Al ₂ O ₃ ) is 0 to 20% by weight; cerium oxide (SiO ₂ ) is 0 to 40% by weight, and harmful heavy metal elements are 300 to 10000 ppm.

Continuing with the foregoing, the water washing step is to wash the incineration fly ash and water of the garbage power plant with a liquid-solid weight ratio of 1:2 to 1-20, so that the water-soluble salts in the incineration fly ash of the garbage power plant are washed with water. However, at the same time, part of the heavy metal can be washed and taken out, and as for the garbage plant, the amount of liquid-solid ratio washing in the incineration fly ash and water can be adjusted according to the amount of water-soluble salt in the incineration fly ash of the power plant. In addition, the pressure filtration step is to dewater the incineration fly ash of the garbage power plant through a filter press, and the water content thereof can be controlled within 5 to 60%, and the incineration fly ash of the garbage power plant is pressed into a mud cake shape; Finally, the mixing step prepares an agent having a pH value of 12 to 15.6 and a hydroxide ion volume molar concentration of 0.01 M to 37.5 M (ie, M: volume Moire concentration), and the agent and the garbage power plant The incineration fly ash is mixed with a liquid-solid ratio of 0.2 to 1.5 to generate a temperature of about 35 ° C to 80 ° C through the chemical reaction between the agent and the incineration fly ash agitation process of the garbage power plant, so that the waste water in the waste power plant is contained in the fly ash. Class reacts with the strong base For example, when the medicament is sodium hydroxide, the ammonia salt in the incineration fly ash of the garbage power plant reacts with sodium hydroxide to produce ammonium hydroxide and discharges ammonia gas due to an increase in temperature, and the waste metal plant incinerates the heavy metal contained in the fly ash. The dust will react with sodium hydroxide to produce high temperature, ie heavy metal hydroxide, and discharge hydrogen. The discharge of part of ammonia can reduce the water-soluble substances in the fly ash for subsequent application, and the harmful heavy metals form hydroxides, so that the heavy metals are dissolved. The rate is reduced. In this way, a stabilizing waste power plant can be formed to incinerate fly ash, so that the fly ash can not be solidified and buried only in a limited manner, and a renewable resource material can be formed more widely.

The present embodiment is described below with reference to several experimental examples: Referring to FIG. 2, Experimental Example 1, in this embodiment, the incineration fly ash of the garbage power plant is taken as a fluidized bed incineration fly ash, and the result of water washing with different liquid-solid ratios is taken as an example. Whether the water-soluble salt in the content is reduced by conductivity, as shown in Fig. 2, when the water is washed with water, the conductivity is lower, so it can be confirmed that the water washing step can be initially The water-soluble salts in the incineration fly ash of the power plant are reduced to facilitate subsequent processing.

Referring to Fig. 3, in the mixing step, the garbage power plant incinerates the fly ash with different mixed liquid-solid ratios of the medicament, and tests the harmful heavy metals Cd, Cr, Cu contained in the toxic characteristic dissolution test (TCLP). , Pb, Ni, Zn, As, Hg dissolution rate; when no agent is added (liquid-solid ratio is 0), and when added to 1.9, the results of the respective harmful metal dissolution rate are detected.

Continuing the foregoing, as shown in FIG. 3, in the present experimental example, the alkaline agent is used as the pH of 15.31, and the garbage power plant incinerated fly ash and the agent have a liquid-solid ratio of 1:0.2, which is not added. When the drug is used, its Cd is 5.62 ppm, Cr is 3.15 ppm, Cu is 16.45 ppm, Pb is 7.12 ppm, Ni is 10 ppm, and Zn is 43.15 ppm. When the liquid-solid ratio is 1:0.8, only Cd is left. 0.016 ppm, Cr is 0.347 ppm; in addition, when the liquid-solid ratio is 1:1.4, only Cr is 0.218 ppm, so it is possible to reduce the dissolution of harmful heavy metals through the liquid-solid ratio range; When the solid ratio is 1:1.9, although the dissolution rate of Cr is 0.015 ppm, the dissolution rate of Pb is 0.91 ppm and Zn is 2.26 pp. Therefore, the best range of liquid-solid ratio is 0.2 to 1.5, can effectively reduce the dissolution rate of the overall harmful metals.

Referring to Figure 4, the stability of the incineration fly ash of the waste power plant after the test is tested, and the stability and compressive strength of the incineration fly ash of the waste power plant are replaced by 10% cement according to the ASTMC 109 specification. The results are shown in the figure. When the incineration fly ash of the garbage power plant is not treated with the agent, the solidified solid will be destroyed by expansion, which is very unstable and cannot measure its compressive strength; in addition, after stabilization, the liquid-solid ratio is 1:0.2 The garbage incineration fly ash from the garbage power plant obtained during mixing will not be damaged by expansion, and the compressive strength can be smoothly measured to be about 150 kgf/cm ² ; in addition, the liquid-solid ratio is 1:1.4. At the time, the obtained waste water plant incineration fly ash will have a compressive strength of about 265 kgf/cm ² , and when it is mixed with a liquid to solid ratio of 1:1.9, the compressive strength will be reduced to about 185 kgf/ cm ^2; Accordingly, may be informed that the cake after water washing step, solid to liquid ratio of 1: 0.2 to 1.4 when mixed, that regardless of the rate of elution of harmful metals, as well as during subsequent use of the compressive strength, have some Excellent performance to ensure that the waste power plant incinerates fly ash Again the effectiveness of resources.

In summary, the method for stabilizing fly ash in a waste water power plant of the present invention sequentially passes the water washing step and the pressure mixing step to the incineration fly ash of the garbage power plant through water washing and pressure filtration to a moisture content of 5 to 60%. After the mud cake, the incineration fly ash and the medicament are liquid-solidified after the treatment with a medicament having a pH value of 12 to 15.6 and a hydroxide ion volume molar concentration of 0.01 M to 37.5 M. After mixing with 0.2~1.5, the agent reacts with the incineration fly ash of the garbage power plant to form a high temperature during the stirring process, and achieves the stabilization effect of exhaust gas and ammonia removal, so that the stabilized waste power plant incineration fly ash can be recycled again. The effect.

The above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, that is, the simple equivalent changes and modifications made in accordance with the scope of the present invention and the contents of the description of the invention. All should remain within the scope of the invention patent.

no

1 is a flow chart of a preferred embodiment of the present invention. 2 is a diagram showing the conductivity of the fly ash washed with different liquid-solid ratios in a water washing step in accordance with a preferred embodiment of the present invention. 3 is a graph showing the results of stabilizing the fly ash heavy metal after the medicament is stabilized according to different liquid-solid ratios according to a preferred embodiment of the present invention. 4 is a test result of stability and compressive strength after treatment according to a preferred embodiment of the present invention.

Claims (3)

A garbage power plant incineration fly ash stabilization method comprises the following steps: a preparation step, which comprises a waste water plant incineration fly ash containing 10 to 75% by weight of calcium oxide; and a water washing step, which incinerates the waste power plant The ash is washed with a liquid-solid weight ratio of 1:2 to 1-20; a pressure filtration step, which passes the incineration fly ash of the garbage power plant through a filter press, and presses the sludge into a mud cake having a water content of 5 to 60%. And a mixing step, which is provided with a medicament having a pH value of 12 to 15.6 and a molar concentration of hydroxide ions of 0.01 M to 37.5 M, and the medicament is incinerated with the fly ash by the garbage power plant after the treatment. 0.2~1.5 liquid-solid weight ratio is mixed to generate high temperature and exhaust gas through the chemical reaction between the agent and the incineration fly ash agitation process of the garbage power plant to form a stable quality waste power plant incineration fly ash. According to the method of claim 1, the garbage plant power plant incineration fly ash stabilization method, wherein the waste power plant incineration fly ash is incinerated fly ash of a mechanical hearth incinerator. According to the method of claim 1, the garbage plant power plant incineration fly ash stabilization method, wherein the waste plant incineration fly ash is incinerated fly ash of a fluidized bed incinerator.