JP2007223841A - Method for producing artificial aggregate using waste slag as main raw material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide artificial aggregate as an alternative for natural aggregate for effective utilization of sewage sludge, domestic waste or industrial waste. <P>SOLUTION: This artificial aggregate is produced by the steps of pulverizing a raw material comprising 100 parts (weight ratio) of waste slag such as molten sludge slag and incinerated ash slag, 20-100 parts of a clayey component such as coal ash and 5-40 parts of a caking additive such as bentonite, kneading and granulating the material, and firing the granule at 1,100-1,250°C. The strength of artificial aggregate of the invention is attributable to anorthite deposited in the slag as a binder. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to effective utilization of sludge molten slag and incinerated ash slag, and in view of the current situation of natural aggregate depletion, provides an alternative artificial bone and a method for producing the same.

  JP-A-6-166579 relates to the effective use of coal ash, and relates to a lightweight aggregate in which waste slag is used for coal ash mutual bonding, and the melted waste slag is foamed by air expansion that is contained in coal ash. It was a thing. Since the slag melt is merely filled between the coal ash particles, the preferred blend ratio does not exceed 40 parts of slag melt per 100 parts of coal ash, and waste slag consumption. From the viewpoint, it is not necessarily a preferred application, and fine cracks are likely to occur due to the difference in expansion coefficient between the coal ash and slag melt binders, and the manufactured aggregate is a lightweight artificial with high crushing strength. It couldn't be aggregate.

  Conventionally, sewage sludge generated from various sewage treatment plants has been disposed of in landfills as it is disposed of in landfills because of sanitary or odor pollution problems. In addition to the difficulty in securing land for landfill, secondary pollution caused by landfill disposal, such as elution of heavy metals from incineration ash, has become a major social problem. Since then, most of these incineration ash has been further melted and slagged to reduce and stabilize it, but most of it has been sent to landfills and cannot be said to be used effectively. Therefore, as an effective use of sewage sludge, general waste or industrial waste, it is a problem to be solved by the present invention to provide as an alternative to natural aggregates such as river gravel that is being depleted. Furthermore, the provision of an artificial aggregate having a crushing strength of 5 KN or more is a problem to be solved by the present invention.

  It is easily conceived to make a so-called pottery product in which sludge molten slag or incinerated ash slag is mixed with coal ash using a binder, granulated and sintered. However, when viewed from the strength of the fired product, bonding by sintering is weak at a firing temperature of 1100 ° C., and at 1200 ° C. or higher, sludge molten slag or incinerated ash slag itself melts and softens, making it impossible to maintain the shape of the fired product. However, in any case, the strength of the fired product was weak, and for example, it could not be used as an artificial aggregate.

  However, the inventor mixed these incineration ash slag and sludge molten slag with coal ash and waste clay at a certain ratio, pulverized to a particle size of 20 to 100 μm, granulated, and as a firing schedule For example, if the temperature is kept from room temperature to 1200 ° C. for 2 hours and further in the firing temperature range for 2 hours, anorthite crystals are generated from the surface of finely pulverized incinerated ash slag and sludge molten slag. Has increased the viscosity of softened slag, and it has been discovered that the softened slag can act as a binder that binds coal ash or waste clay together to form a strong aggregate.

  According to the X-ray diffraction measurement, as a firing schedule (heat treatment), 2 hours from room temperature to 1200 ° C was held for 2 hours and then cooled for 2 hours. The crystal peak is clearly seen in a sample made from powder pulverized to a center particle size of 60 μm. That is, it can be seen that anorthite crystals were precipitated by the effect of powdering.

  At 1200 ° C, when the waste slag alone is used as a raw material, the sample shows softening deformation, and the anorthite crystals that have partially precipitated once disappear, but are discarded by kneading with materials containing clay components such as waste clay and coal ash. It can be seen that the anorthite formation of the matrix layer of material slag is substantially accelerated even at 1200 ° C.

  When coal ash is mixed with the sludge molten slag powder, the sludge molten slag component reacts with the coal ash at about 1100 ° C. to generate anorcite. When the proportion of coal ash increases, the fired product will not soften even when the firing temperature reaches 1200 ° C. Sintering strength that cannot be expected with sludge molten slag or coal ash alone is produced by the action of anorthite crystals intervening in the slag matrix, and a strong fired product, that is, a high-strength artificial bone can be produced.

  Table 1 shows the influence of the mixing ratio of the sludge molten slag and the firing temperature on the strength (crush strength). The crushing strength increases as the amount of sludge melted slag in the raw material ratio increases and the firing temperature increases. However, the strength decreases when the heat treatment conditions allow the slag to soften, melt and foam. The absolute dry specific gravity shows the same tendency as the strength, and the specific gravity increases as the sludge melt slag amount increases. When the sludge melt slag is softened, melted and foamed, the specific gravity is reduced. The trend of water absorption is consistent with the trend of specific gravity. In any case, the properties of the artificial aggregate change depending on the content of the sludge molten slag.

  The manufacturing method of the artificial aggregate of this invention is described.

  Bentonite is added as a binder to sludge molten slag, incinerated ash slag and coal ash finely pulverized to a particle size of 20 to 100 μm, and water is added to knead and granulate. If the granulated product is dried and fired, a lightweight and high-strength granular aggregate can be obtained. In an actual manufacturing process, 20-100 parts of coal ash is added to 100 parts (weight ratio) of sludge molten slag and incinerated ash slag, and 5-40 parts of bentonite as a binder is added and kneaded, and a granulator A spherical shaped body with a diameter of 5 to 20 mm is made through After the spherical shaped body is dried, it is put in a firing kiln, a predetermined time is taken until the firing temperature range, the firing temperature is maintained at 1200 ° C. for a certain time, and then the fired product is allowed to cool. A fired product, that is, an artificial aggregate having a crushing strength of 6 to 10 KN was obtained.

  The raw materials are waste slag, clay material and binder. Waste slag refers to molten slag having a relatively high content of CaO, such as sewage sludge molten slag, general waste incinerated ash molten slag, and converter slag. The clay material is a material having a relatively large content of SiO2 and Al2O3 such as waste clay and coal ash. Further, the binder means a material that imparts a viscosity necessary for granulating the mixed powder of waste slag and clay, and clay such as bentonite and organic binders such as methyl cellulose are used. In production, these raw materials are weighed and mixed and pulverized to a center diameter of about 30 μm by a pulverizer such as a vertical mill or a ball mill.

  In order to granulate and form the three raw materials, the amount of water to be added is about 30% or less, and the amount is determined by the characteristics of the mixing, kneading, and granulator, but in order to shorten the time required for the drying process, It is better to have as little moisture as possible. As the granulator, a pan type or a pressure extrusion type can be used.

  A rotary kiln is desirable as a firing machine for the spherical molded body from the viewpoint of cost, but a shuttle kiln, a tunnel kiln or the like may also be used. In the firing schedule, it took 2 hours from room temperature to the firing temperature, and 2 hours in the firing zone of 1000 to 1200 ° C. Thereafter, the mixture was allowed to cool to obtain a granular artificial aggregate. This aggregate has an absolute dry specific gravity of about 2, a water absorption rate of 1% or less, and a crushing strength of 6 kN or more.

  The present inventor completed the present invention based on the above facts. That is, after pulverizing, kneading and granulating a raw material consisting of 20 to 100 parts of a clay component and 5 to 40 parts of a binder with respect to 100 parts (weight ratio) of waste slag, firing is performed at 1100 to 1250 ° C. To manufacture artificial aggregate.

  The manufacturing method of the artificial lightweight aggregate of Claim 1 which added 0.5-5 parts of foaming agents to the raw material of Claim 1.

  An artificial aggregate or an artificial lightweight aggregate obtained by mainly depositing anorthite on a matrix layer of a fired product produced by using the production method according to claim 1 or 2.

  The reason why the clay component is limited to 20 to 100 parts with respect to 100 parts (weight ratio) of the waste slag is that the effect of adding the clay component is less than 20 parts. If it exceeds 100 parts, a strong artificial aggregate cannot be obtained.

  The reason why the binder is limited to 5 to 40 parts with respect to 100 parts (weight ratio) of waste slag is that granulation is difficult if it is less than 5 parts, and if it exceeds 20 parts, the strength of the artificial aggregate is reduced. There is a fear.

  Although the above description of the present invention is mainly for the production of coarse aggregates, fine aggregates can be obtained by crushing large-sized ceramic products such as clay pipes or fired artificial aggregates by changing the size of the compact. Of course, it is also possible to manufacture.

  The aggregate of the present invention is not a lightweight aggregate mainly composed of commercially available industrial waste, but rather resembles natural gravel with a high strength, and is quite lightweight, so that the weight of the concrete structure can be reduced. Thus, the cost of the building can be reduced.

  The aggregate of the present invention was actually manufactured. Waste slag, 100 parts (by weight) of sewage sludge slag, 30 parts of clay ash, and 5 parts of bentonite as a binder were mixed and ground in a ball mill mixer, and pulverized to a center particle size of about 50 μm. Water was added to the material and kneaded to make a clay. This kneaded material was granulated with a granulator to obtain a spherical molded body having a diameter of about 10 mm. After this granulated product was dried with a dryer, it was put in a rotary kiln, held at 1200 ° C. for 2 hours and 1200 ° C. for 2 hours, and then allowed to cool.

  The artificial aggregate thus produced was a spherical artificial aggregate exhibiting properties of a crushing strength of 9 N, a specific gravity of 1.9, and a water absorption rate of 0.3%.

Since the present invention effectively uses a large amount of waste slag, it itself contributes to reducing the environmental load. However, when looking at the current situation of natural aggregate depletion, the present invention can provide an alternative aggregate. Believes that it contributes greatly to the conservation of the global environment.

Claims (3)

  Artificial bone which is baked at 1100 to 1250 ° C. after pulverizing, kneading and forming a raw material consisting of 20 to 100 parts of a clay component and 5 to 40 parts of a binder with respect to 100 parts (weight ratio) of waste slag A method of manufacturing the material.   The manufacturing method of the artificial lightweight aggregate of Claim 1 which added 0.5-5 parts of foaming agents to the raw material of Claim 1. An artificial aggregate or an artificial lightweight aggregate obtained by mainly depositing anorthite on a matrix layer of a fired product obtained by molding and firing the raw material according to claim 1 or 2.