JP2009007233A - Porous ceramic body and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a porous ceramic body prepared by using bottom ash as a part of a raw material, having no risk of toxic heavy metal leaching, and used for e.g., water-permeating and water-holding materials, filter materials, microbe-supporting water purifying materials, sound-absorbing materials, fireproof heat-insulation materials, or planting materials and to produce its production method. <P>SOLUTION: The porous ceramic body comprises a fired or sintered compact of, by wt.%, 1-70% fly ash, 4-60% glass, and 1-80% bottom ash. The method for producing the porous ceramic body comprises pulverizing a raw material comprising, by wt.%, 1-70% fly ash, 4-60% glass or waste glass, and 1-80% bottom ash into particles, mixing the pulverized raw material, firing the resultant mixture for 1-120 min in a temperature region of 600-1,100°C under the exclusion of air, and cooling the fired product under the exclusion of air. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ceramic porous body made from bottom ash (clinker ash), fly ash, and waste glass discharged from a coal-fired power plant or the like, and a method for producing the same.

  From the long-term perspective of oil supply and demand in the world, coal-fired power generation has been emphasized in power supply, and the ratio will inevitably increase in the future. Correspondingly, the amount of coal ash generated is 10.8 million tons per year (2002, Coal Energy Center). Of the generated coal ash, 9.73 million tons / year is cement manufacturing, civil engineering, and construction (lightweight) The remaining 1.70 million tons / year is disposed of in landfills.

  About 90% of coal ash from coal burned at a coal-fired power plant or the like is fly ash, and 10% is bottom ash (clinker ash). Fly ash is fine coal ash collected by a dust collector, and bottom ash is massive coal ash collected at the bottom of the boiler and is also called clinker ash.

  However, bottom ash (clinker ash) contains hazardous heavy metals such as arsenic, cadmium, and lead. When landfilling bottom ash (clinker ash), there is a risk of elution, and management-type disposal ( In order to prevent harmful heavy metals from flowing into groundwater, etc., they are subject to landfill disposal with a shutoff facility, and the disposal involves high costs. As shown in Tables 6 and 7, this is because the amount of elution from the bottom ash is much larger than that of fly ash. The technology for making bottom ash (clinker ash) low-cost harmless and resource-recycling is strongly desired.

  On the other hand, waste glass (excluding plate glass) is released 2.6 million tons per year, of which 16.5 million tons / year is reused. The remaining 950,000 tons / year is landfilled as waste. The amount of waste glass discarded will continue to increase, and a technology for its effective use is desired.

On the other hand, a clinker is formed through a porous crystallized glass made of soda-lime glass and hydraulic cement having bottom ash (clinker ash) as an aggregate and covering at least a part of its surface and having 10 to 100 μm through holes. A ceramic sintered body in which ash is partially bonded and pores of 100 μm to 500 μm are provided between the clinker ash particles is known (see Patent Document 1). And in this prior art, there also exists an aspect which adds fly ash in 20 weight% or less.
Japanese Patent Laid-Open No. 11-139886

Patent Document 1 cannot teach the problem of solving the problem of elution of harmful heavy metals such as arsenic, cadmium, and lead contained in bottom ash (clinker ash) and technical means for solving the problem. The essential porous crystallized glass in this prior art is composed of soda-lime glass and hydraulic cement. Thus, a separate process for producing porous crystallized glass is required.
The present invention uses a bottom ash (clinker ash), which has heretofore been exclusively managed landfill disposal, as a part of the starting material, a water-permeable / water-retaining material, a filtering material, which has no risk of elution of harmful heavy metals, An object of the present invention is to provide a ceramic porous body used as a water purification material, a sound absorbing material, a fireproof heat insulating material, a planting material and the like carrying microorganisms, and a method for producing the same.

  The invention according to claim 1 for solving the above-mentioned problems is a sintered body or sintered body of fly ash: 1% to 70%, glass: 4% to 60%, bottom ash: 1% to 80% by weight. It is a ceramic porous body consisting of a body.

  The invention according to claim 2 is a raw material of fly ash: 1% to 70%, glass or waste glass: 4% to 60%, and bottom ash: 1% to 80% by weight. Is a method for producing a porous ceramic body that is cooled in an air-blocked state after firing for 1 minute to 120 minutes in a temperature range of 600 ° C. to 1100 ° C. in an air-blocked state. .

  According to the present invention, since the waste glass in the blended raw material functions as a binder, it is not necessary to add a separate binder, and a ceramic porous body having excellent strength can be obtained. In addition, harmful heavy metals such as As, Pb, and Cd contained in bomb ash (clinker ash) are confined in the glass skeleton (glass solidified), and almost no elution from the ceramic porous body occurs.

  In addition, the combustion of gas-generating elements such as carbon and sulfur contained in fly ash results in the formation of many closed cells → continuous pores (pores) in the molten glass. A mass can be obtained. This ceramic porous body can be used as an element to purify microorganisms in the pores and purify the water quality, as well as water permeable and water retaining materials, filtration materials, sound absorbing materials, fireproof and heat insulating materials, planting materials Etc. can be used.

The ceramic porous body of the present invention uses fly ash, waste glass, and bottom ash (clinker ash) as starting materials, and these materials are blended at a specific ratio, pulverized and mixed, and then in an air-blocked state, 600 It can be obtained by baking for 1 minute or more, preferably 10 minutes to 120 minutes in a temperature range of 1 ° C to 1100 ° C.
Examples of chemical compositions of these starting materials are shown in Tables 1 to 3.

  Table 4 shows an example of heavy metals contained in coal ash.

The blending ratio of the starting materials is, by weight, fly ash: 1% to 70%, waste glass: 4% to 60%, and bottom ash (clinker ash): 1% to 80%.
A flysh usually contains several percent of carbon and sulfur by weight, and these are burned, gasified and melted during the firing process to form closed cells → open pores, and finally countless Form continuous pores. Thus, at least 1% of fly ash is necessary. If the blending ratio is less than this, the formation of continuous pores (pores) due to carbon and sulfur combustion and gasification becomes insufficient. On the other hand, if fly ash content exceeds 70%, the mixing ratio of waste glass and bottom ash is made too small, especially if the amount of waste glass that functions as a binder is made too small to make sintering insufficient, and the resulting ceramic porous Insufficient strength of the material.

  Waste glass functions as a binder and increases the blending ratio thereof, thereby increasing the strength of the ceramic porous body obtained by improving the sinterability. Thus, if the blending ratio is less than 4%, the sintering is insufficient and the resulting ceramic porous body is insufficient in strength. On the other hand, when the blending ratio exceeds 60%, the blending ratio of fly ash and bottom ash (clinker ash) becomes too small, and the formation of continuous pores (pores) becomes insufficient.

  The blending ratio of fly ash, waste glass, and bottom ash (clinker ash) is preferably fly ash: 10% to 60%, waste glass: 15% to 50%, bottom ash (clinker ash): 10% to 70 %.

  The starting material having the above blending ratio is preferably granular powder of 100 μm or less, mixed and heated in a temperature range of 600 ° C. to 1100 ° C. for 1 minute or more, preferably 10 minutes to 120 minutes in an air-blocked state. The ceramic porous body having continuous pores (pores) having a diameter of several μm to several mm is obtained by natural cooling in an air-blocked state.

  The starting material is pulverized to 100 μm or less, and the mixture obtained by adding water to the raw material mixture is poured into a mold to obtain a molded product, which is naturally dried, and then in a temperature range of 600 ° C. to 1100 ° C. in an air-blocked state. The ceramic porous body having a desired shape having continuous pores (pores) of several μm to several mm in diameter after being baked for 1 minute or longer, preferably 10 minutes to 120 minutes, and naturally cooled in an air-blocked state. It can also be obtained.

  When the heating temperature in the firing process is less than 600 ° C., the waste glass in the blended raw material does not melt and diffuses without forming pores even if carbon and sulfur in the fly ash burn and gasify. On the other hand, when the temperature exceeds 1100 ° C., the glass is almost completely melted, and all the gas is expelled. Thus, the ceramic porous body is preferably formed by forming closed cells → continuous pores (pores) with a gas generated by burning carbon or sulfur in a glass melted at a temperature range of 650 ° C. to 1050 ° C. It is good to do.

  If the heating time is less than 1 minute, a sintered body cannot be obtained. Preferably, it is at least 10 minutes. Moreover, the heating time exceeding 120 minutes causes an increase in heating cost.

  By weight, fly ash: waste glass: bottom ash (clinker ash) = 1: 1: 1 as a starting material, these were pulverized to 100 μm or less and mixed, then 900 ° C. × 60 minutes, 1000 ° C. X Heating and firing were carried out with an electric heater in a crucible in an air shut-off state under process conditions of 60 minutes. Then, it was naturally cooled to room temperature in a crucible in an air-blocked state to obtain a ceramic porous body having continuous pores (pores) having a diameter of several μm to several mm.

  A water purification test was conducted by the soaking filter bed method using the obtained ceramic porous body. The result is shown in FIG. 1 (COD value). Moreover, the time-dependent change of a BOD value is shown in FIG. As apparent from FIG. 1 and FIG. 2, COD: about 400 mg / L and BOD: about 800 mg / L at the beginning (day 0) showed COD: 30 mg on the third day. / L and BOD: about 30 mg / L. Thereafter, the value gradually decreased, and on the 15th day, COD was purified to about 10 mg / L and BOD was purified to 7 mg / L.

  By weight, fly ash: waste glass: bottom ash (clinker ash) = 5: 2: 1 as a starting material, pulverized to 100 μm or less and mixed, then 900 ° C. × 60 minutes, 1000 ° C. X Heating and firing were carried out with an electric heater in a crucible in an air shut-off state under process conditions of 60 minutes. Then, it was naturally cooled to room temperature in a crucible in an air-blocked state to obtain a ceramic porous body having continuous pores (pores) having a diameter of several μm to several mm.

  A water purification test was conducted by the soaking filter bed method using the obtained ceramic porous body. The results are shown in FIG. 1 (COD value) together with that of Example 1. Moreover, the time-dependent change of a BOD value is combined with the thing of Example 1 in FIG. As apparent from FIG. 1 and FIG. 2, COD: about 400 mg / L and BOD: about 800 mg / L at the beginning (day 0) showed COD: 120 mg on the third day. / L, BOD: about 180 mg / L. Thereafter, the value gradually decreased, and on the 15th day, COD was purified to 10 mg / L or less and BOD was purified to 2 mg / L.

The eluate of the ceramic porous body obtained in Example 1 and Example 2 was analyzed according to the following procedure.
1) A ceramic porous body and ultrapure water (10 times the weight of the ceramic porous body) were placed in a plastic container, and charged in a shaking thermostat (30 ° C.) for 6 hours.
2) Thereafter, the ceramic porous body was taken out, and the eluate was suction filtered.
3) One liter of the filtrate was collected and analyzed by the Kyushu Environmental Management Association. The results are shown in Table 5.

  As is apparent from Table 5, in the ceramic porous body of the present invention, the leaching amount of harmful heavy metals is far below the emission standard value, which is a very low value equal to or less than the environmental standard value. Therefore, it can be used as a safe purification element that purifies water by sprinkling microorganisms.

The graph which shows the result of the water purification test (COD) by the immersion filter bed method using the ceramic porous body which concerns on this invention Example The graph which shows the result of the water purification test (BOD) by the immersion filter bed method using the ceramic porous body which concerns on an Example of this invention

Claims (2)

  A ceramic porous body comprising a fired body or a sintered body of fly ash: 1% to 70%, glass: 4% to 60%, and bottom ash: 1% to 80% by weight.   By weight, fly ash: 1% -70%, glass or glass cullet: 4% -60%, bottom ash: 1% -80% A method for producing a ceramic porous body, characterized in that after firing in a temperature range of 600 ° C. to 1100 ° C. for 1 minute to 120 minutes, cooling is performed in an air-blocked state.

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