JP2012131702A - Method of manufacturing ceramic porous body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a ceramic porous body used as a water-permeable/holding material, a filtering material, a microorganism carrying water purification material, a sound absorption material, a moisturization material, a fireproof heat-insulation material, and a material for planting that have no risk of harmful heavy metal elution, using, as a part of starting material, bottom ash (clinker ash) that is conventionally to exclusively undergo control type landfill disposal.SOLUTION: Granular powder bodies are formed from raw materials of 10-60% of fly ash, 15-50% of waste glass, 10-70% of bottom ash (clinker ash) in weight as mixing ratio. The raw materials are mixed and burned in a temperature region of 600-1,100°C for 10-120 minutes under an air shielded state, and then are cooled under the air shielded state.

Description

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

  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 therefore managed disposal. It is subject to disposal (landfilled with a shut-off facility so that harmful heavy metals do not flow into groundwater etc.), 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.

  However, Patent Document 1 teaches a 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. Absent. 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 conventionally been exclusively managed landfill disposal, as a part of the starting material, a water-permeable / water-retaining material, a filtering material, without the risk of elution of harmful heavy metals, It aims at providing the manufacturing method of the ceramic porous body used as a water purification material, a sound absorption material, a moisture retention material, a fireproof heat insulation material, a planting material etc. which carry microorganisms.

  In order to solve the above problems, the present invention provides, by weight, raw materials having a blending ratio of fly ash: 10% to 60%, waste glass: 15% to 50%, and bottom ash (clinker ash): 10% to 70%. The ceramic porous material is made into granular powder, mixed with the raw materials, fired in a temperature range of 600 ° C. to 1100 ° C. for 10 minutes to 120 minutes in an air-blocked state, and then cooled in the air-blocked state. It is a manufacturing method of a mass.

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

  In addition, the ceramic porous body with a large specific surface area and excellent water absorption is formed by the combustion of elements such as carbon and sulfur contained in fly ash, and many closed cells → continuous pores (micropores) are formed in the molten glass. Can be obtained. This ceramic porous body can be used as an element for purifying the water quality by allowing microorganisms to be contained in the fine pores, as well as water permeable and water retaining materials, filtration materials, sound absorbing materials, moisture retaining materials, fireproof and heat insulating materials, It can be used as a planting material.

It is a 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 the Example of this invention. It is a 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 the Example of this invention.

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 is obtained by performing baking for 10 minutes to 120 minutes in a temperature range of from 1 to 100 ° 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: 10% to 60%, waste glass: 15% to 50%, and bottom ash (clinker ash): 10% to 70%.
Fries usually contain several percent of carbon and sulfur by weight, and in the firing process, these burned, gasified and melted to form closed cells → open pores (micropores), and finally countless The continuous pores (micropores) are formed. Therefore, at least 10% of fly ash is necessary. If the blending ratio is less than this, the formation of continuous pores (micropores) due to the combustion and gasification of carbon and sulfur becomes insufficient. On the other hand, if fly ash content exceeds 60%, 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 15%, the sintering is insufficient and the resulting ceramic porous body is insufficient in strength. On the other hand, if the blending ratio exceeds 50%, the blending ratio of fly ash and bottom ash (clinker ash) becomes too small, and the formation of continuous pores (micropores) becomes insufficient.

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

  The starting material is pulverized to 100 μm or less, and the mixture obtained by adding water to the starting material mixture is poured into a mold to obtain a molded product. The ceramic porous body having a desired shape having continuous pores (micropores) having a diameter of several μm to several mm can be obtained by firing for 10 minutes to 120 minutes and naturally cooling in an air-blocked state.

  If the heating temperature in the firing process is less than 600 ° C., the waste glass in the blended raw material does not melt, and even if carbon and sulfur in the fly ash burn and gasify, they diffuse without forming fine pores. On the other hand, when the temperature exceeds 1100 ° C., the glass is almost completely melted, and most of the gas generated in the glass phase is quickly released out of the system. Thus, it is preferable to form closed cells → continuous pores (micropores) efficiently by 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 have a body.

  If the heating time is less than 10 minutes, it is difficult to obtain a satisfactory sintered body. On the other hand, when the heating time exceeds 120 minutes, the fine holes are connected to increase the size of the holes and increase the manufacturing cost.

  By weight, fly ash: waste glass: bottom ash (clinker ash) = 1: 1: 1 as a starting material, these were finely pulverized to 100 μm or less, mixed, 900 ° C. × 60 minutes, and 1000 It heated and baked in the electric furnace using the crucible in the air shut-off state on the process conditions for 60 degreeC x 60 minutes. Thereafter, the sintered body was naturally cooled to room temperature in an electric furnace in an air shut-off state to obtain a ceramic porous body having continuous pores (micropores) 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 values 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 (62.5%: 25.0%: 12.5%) The starting material was used as a starting material, and these were reduced to 100 μm or less. After being finely pulverized and mixed, heating and firing were performed in an electric furnace using a crucible in an air-blocked state under process conditions of 900 ° C. × 60 minutes and 1000 ° C. × 60 minutes. Then, the sintered compact was naturally cooled to room temperature together with the crucible in an air shut-off state to obtain a ceramic porous body having continuous pores (micropores) 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 requested for component analysis 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 ceramic porous body obtained by the present invention can be used as an element for purifying microorganisms in the micropores and purifying water quality, as well as water permeable / water retaining materials, filtration materials, sound absorbing materials, moisture retaining materials, fireproof materials. It can be used as a heat insulating material, a planting material or the like.

Japanese Patent Laid-Open No. 11-139886

Claims (1)

The raw materials with a blending ratio of fly ash: 10% to 60%, waste glass: 15% to 50%, bottom ash (clinker ash): 10% to 70% by weight are made into granular powder, and the raw materials are mixed A method for producing a ceramic porous body, wherein firing is performed in a temperature range of 600 ° C. to 1100 ° C. for 10 minutes to 120 minutes in an air-blocked state, and then cooling is performed in an air-blocked state.

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