Provided is a refractory aggregate that is for casting sand and that comprises spherical refractory sintered particles artificially produced by a sintering method, and that can improve the fluidity of the casting sand and can achieve excellent mold strength. This refractory aggregate is for casting sand, comprises spherical refractory sintered particles artificially produced by a sintering method, is configured to have a roundness of at least 0.70 and an average particle size of 0.01-1.00 mm, and is configured such that the total volume of pores having a pore size of 2-10 μm as measured with a mercury intrusion porosimeter is in the range of 0.20-0.50 mL/g, and the amount of fine powder is additionally mixed such that the turbidity as measured by turbidimetry is at most 3000 NTU.
Provided is a refractory aggregate that is for casting sand and that comprises spherical refractory sintered particles artificially produced by a sintering method, and that can improve the fluidity of the casting sand and can achieve excellent mold strength. This refractory aggregate is for casting sand, comprises spherical refractory sintered particles artificially produced by a sintering method, is configured to have a roundness of at least 0.70 and an average particle size of 0.01-1.00 mm, and is configured such that the total volume of pores having a pore size of 2-10 μm as measured with a mercury intrusion porosimeter is in the range of 0.20-0.50 mL/g, and the amount of fine powder is additionally mixed such that the turbidity as measured by turbidimetry is at most 3000 NTU.
B22C 1/00 - Compositions of refractory mould or core materialsGrain structures thereofChemical or physical features in the formation or manufacture of moulds
B33Y 80/00 - Products made by additive manufacturing
B33Y 70/00 - Materials specially adapted for additive manufacturing
Provided is an effective method for reproducing molding sand that has been used in the making of a mold using an inorganic binder containing a liquid glass as the main component thereof from the mold that has been casted. In order to reproduce molding sand comprising artificial spherical refractory particles from a mold that is made using the molding sand and an inorganic binder containing a liquid glass as the main component thereof, the following steps are employed: a step of crushing the mold that has been used and simultaneously separating and removing a fine powder; a crushing/sizing step of sizing the ground product to obtain specific sized sand; a roasting step of subjecting the crushed/sized sand thus produced to a roasting treatment to cause the crystallization of a liquid glass component adhered to the surface of the sand; and a polishing step of mechanically polishing the crushed/sized sand that has been subjected to the roasting treatment to separate the crystallized liquid glass component on the surface of the sand, then collecting the crystallized liquid glass component thus separated using a dust collector and then removing the separated crystallized liquid glass component.
B22C 1/00 - Compositions of refractory mould or core materialsGrain structures thereofChemical or physical features in the formation or manufacture of moulds
B22C 5/00 - Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose
4.
METHOD FOR REGENERATING FLOWING MEDIUM IN FLUIDIZED BED FURNACE
B07B 4/02 - Separating solids from solids by subjecting their mixture to gas currents while the mixtures fall
F23G 5/30 - Methods or apparatus, e.g. incinerators, specially adapted for combustion of waste or low-grade fuels with combustion in a fluidised bed
B01J 8/24 - Chemical or physical processes in general, conducted in the presence of fluids and solid particlesApparatus for such processes with fluidised particles according to "fluidised-bed" technique
Provided are: a useful bed medium for a fluidized bed with good fluidity, the bed medium being usable in a fluidized bed furnace using biomass material and coal material as fuel; and a useful bed medium for a fluidized bed with good durability, the bed medium not easily forming an agglomerate of its particles, and being resistant to collapsing. The bed medium for a fluidized bed in a fluidized bed furnace for combusting or gasifying the fuel is formed of artificially-produced spherical refractory particles containing not less than 40% by weight of Al2O3 and not more than 60% by weight of SiO2 and having an apparent porosity of not more than 5%, and a ratio by weight of agglomerated particles in the bed medium is not more than 20% after three heat treatment tests on the bed medium at 900° C. for 2 hours under coexistence with the fuel.
A porous fired granulated body is formed by consolidating numerous alumina particles to each other while letting mainly interconnected pores remain in network form across an entire cross section of a granulated body particle. The pores have an inner diameter controlled by a droplet diameter of a pore forming agent and have numerous precipitated alumina crystals formed on inner surfaces thereof. Manufacture is performed by spraying the pore forming agent (emulsion) onto a raw material to form a coating layer of the pore forming agent on a surface of the raw material particle and controlling the inner diameter of the pores. A porous fired granulated body of alumina having a high specific surface area and having higher strength for the same specific surface area can thus be provided by a simple manufacturing method.
The present invention provides a useful fluidized medium for a fluidized bed, the fluidized medium having excellent fluidity and being suitable for use as a fluidized medium in a fluidized bed furnace that uses biomass material and coal as fuel. The present invention also provides a useful fluidized medium for a fluidized bed, the fluidized medium having excellent durability, not easily forming an aggregate of particles, and not being easily destroyed. Used as the fluidized medium for a fluidized bed in a fluidized bed furnace that is used to combust or gasify fuel comprising biomass material and/or coal is a fluidized medium that comprises artificially produced spherical refractory particles having a chemical composition comprising 40 wt% or more of Al2O3 and 60 wt% or less of SiO2, having an apparent porosity of 5% or less, and having a weight ratio of 20% or less of aggregated particles after a heating treatment test has been repeated three times at 900ºC×2 hours in coexistence with the fuel.
F23G 5/30 - Methods or apparatus, e.g. incinerators, specially adapted for combustion of waste or low-grade fuels with combustion in a fluidised bed
F23C 10/18 - Apparatus in which combustion takes place in a fluidised bed of fuel or other particles DetailsAccessories
F23G 5/027 - Methods or apparatus, e.g. incinerators, specially adapted for combustion of waste or low-grade fuels including pretreatment pyrolising or gasifying
8.
POROUS BURNED GRANULES AND PROCESS FOR PRODUCING SAME
Porous burned granules produced by consolidating countless alumina particles so that mainly interconnected voids remain in a network state throughout the section of each granule particle (11). The voids (13) have diameters which have been regulated by the droplet diameter of a void-forming agent, and the inner surface has countless alumina crystals (15) deposited thereon. The void-forming agent (emulsion) is sprayed over a raw material to form a coating layer of the void-forming agent on the surface of the particles of the raw material, and the porous burned granules are produced therefrom while regulating the diameters of the voids. With such simple production process, it is possible to provide porous burned alumina granules having a large specific surface area and having even higher strength than ones having the same specific surface area.
To provide a ceramic aggregate for refractories, which enables a refractory to exhibit excellent spalling resistance. This ceramic aggregate for refractories is configured to have (a) a chemical composition that contains 50% by weight or more of Al2O3, 50% by weight or less of SiO2 and 10% by weight or less of impurities, (b) a columnar shape having a length in the major axis direction (L) of 100 mm or less, a length in the minor axis direction (D) of 3 mm or more and an aspect ratio (L/D) of 1.5 or more, and (c) a surface roughness (Ra) of 10 μm or less and a maximum height (Ry) of 100 μm or less.
Providing a method of modifying refractory particles used to produce a casting mold by using a furan resin as a binder, so as to effectively improve a strength of the casting mold and to reduce a required amount of the binder. An artificial aggregate which is artificially produced and which has an apparent porosity of not more than 5% is used as the refractory particles, and the artificial aggregate is subjected to a heat treatment at a temperature of 400-1500° C. for not shorter than one hour in a heating atmosphere having an oxygen concentration of not higher than 15%.
B22C 1/22 - Compositions of refractory mould or core materialsGrain structures thereofChemical or physical features in the formation or manufacture of moulds characterised by the use of binding agentsMixtures of binding agents of organic agents of resins or rosins
B22C 9/02 - Sand moulds or like moulds for shaped castings
C04B 35/626 - Preparing or treating the powders individually or as batches
The present invention addresses the problem of modifying refractory particles, which are to be molded through use of a furan resin as a binder, and thereby attaining an effective improvement in the strength of a mold and a reduction in binder consumption. This method for modifying refractory molding particles comprises: using, as refractory particles which are to be molded through use of a furan resin as a binder, an artificial aggregate which has been produced artificially and which has an apparent porosity of 5% or less; and heat-treating the artificial aggregate in a heating atmosphere having an oxygen concentration of 15% or less at a temperature of 400 to 1500ºC for one or more hours.
B22C 1/00 - Compositions of refractory mould or core materialsGrain structures thereofChemical or physical features in the formation or manufacture of moulds
B22C 1/22 - Compositions of refractory mould or core materialsGrain structures thereofChemical or physical features in the formation or manufacture of moulds characterised by the use of binding agentsMixtures of binding agents of organic agents of resins or rosins
B22C 5/00 - Machines or devices specially designed for dressing or handling the mould material so far as specially adapted for that purpose
patents
