Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
  • C04B18/04—Waste materials; Refuse
  • C04B18/06—Combustion residues, e.g. purification products of smoke, fumes or exhaust gases
  • C04B18/08—Flue dust, i.e. fly ash
  • C04B18/085—Pelletizing
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
  • C04B18/02—Agglomerated materials, e.g. artificial aggregates
  • C04B18/027—Lightweight materials
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
  • C04B38/02—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by adding chemical blowing agents
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27M—INDEXING SCHEME RELATING TO ASPECTS OF THE CHARGES OR FURNACES, KILNS, OVENS OR RETORTS
  • F27M2001/00—Composition, conformation or state of the charge
  • F27M2001/16—Particulate material, e.g. comminuted scrap
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/91—Use of waste materials as fillers for mortars or concrete

Definitions

• the invention relates to a method for foaming fly ash.
• fly ash accumulates in large quantities in modern coal-fired power plants that are dust-fired.
• the use of this fly ash as an additive in the production of concrete is only possible to a limited extent and the landfill of this fly ash which is otherwise required is associated with high expenditure. Overall, it can even be said that the recycling or removal of the fly ash is associated with considerable, environmentally harmful problems.
• the method according to the invention should furthermore in particular be able to create structural bodies which can be used as concrete aggregate from the fly ash, which are light, should be economical to produce and which can also be used as insulating bodies even at very high temperatures of more than 1000 ° C. »
• OMPI silicon nitrite or carbide and alkali salts dissolved in water are added to the fly ash and the mixture foams at the softening temperature of the fly ash.
• Metal oxide such as MnO 2 or Fe-O. Can advantageously be added to the fly ash as a further foaming agent and Na 2 CO (sodium carbonate ) can be used economically as the alkali salt.
• the foamed mixture can consist of very small particles.
• the object according to the invention can advantageously be achieved in particular by adding ferrosilicon nitrite as the silicon nitrate.
• the softening temperature is preferably above 1250 and below 1400 ° C, advantageously about 1330 - 1340 ° C.
• the foam structural bodies produced have a very low density, which can be between 0.25 and 0.50 g / cm.
• the structural bodies produced according to the invention have a very high compressive strength and, since they have a low alkali content, are particularly suitable as concrete aggregates, since they can be described as compatible with concrete. Further refinements of the method according to the invention are mentioned in the subclaims not cited above.
• the process according to the invention is carried out in such a way that after mixing fly ash, in particular the last stage of the filtering, with 2-4% by weight of ferrosilicon nitrite, the mixture is foamed in suitable containers or ovens at temperatures of more than 1250 ° C. .
• fly ash from the last stage of the filtering is particularly easy to foam
• the fly ash from other stages of filtering or mixtures of the fly ash from different filtering stages can also be foamed, although under certain circumstances at slightly different temperatures.
• the foam temperature is dependent on the type of fly ash, which is a function of. the coal used has different composition. But it is generally above 1250 and below 1400 ° C, z. B. between 1330 and ' 1340 ° C.
• the foaming temperature which is to be determined empirically depending on the type of fly ash used, is precisely maintained.
• the fly ash is not sufficient below the foaming temperature
• the mixture of fly ash and the 2-3% by weight of ferrosilicon nitrite mentioned (depending on the type of fly ash, different proportions by weight of the foaming agent can also be used) is filled into molds or placed on a sintering belt, and then briefly the determined foaming temperature exposed. After foaming, the temperature is lowered very quickly and then the foam or structural body produced can be isolated and left to cool down slowly.
• Can be used as "structural bodies produced can be used as fine granules, that is, so-called light sand are generated, Fall ⁇ shafts, fluidized beds, reactors, crucibles, shapes, stoves or other suitable means.
• the new type of structural body can be used as an insulation agent for technical objects, e.g. B. Find industrial furnaces even at quite high temperatures up to 1200 ° C. Since the structural bodies produced, which can have the form of the finest spheres, have almost no alkali content, they can also be used as a concrete aggregate as compatible with concrete.
• the weight of the structural bodies produced can be set by means of the foaming temperature and the proportion of ferrosilicon nitrite, and is between 0.2 and 0.5 g / cm.
• fly ash from the last stages of filtration can be used according to the invention, but surprisingly for those skilled in the art also those from the front filtration stages.
• ferrosilicon nitrite can be used as the foaming agent, but that silicon nitride or carbide can also give good results when used in conjunction with water-soluble alkali salts which are dissolved in water and if in particular a mixture of the foaming agent a metal oxide such as Mn0 2 or F ⁇ 2 ° 3 is added.
• Na 2 CO, (soda) can advantageously be used as the alkali salt.
• the weight of the ferrosilicon nitrite, silicon nitride or carbide is then only about 1% of the fly ash to be foamed, the weights of the other additives as foaming agents are of the same order of magnitude, ie a maximum of a few percent.
• alkali metals All water-soluble and possibly also insoluble compounds of the alkali metals are suitable as alkali salts, lithium, sodium and potassium salts being of particular importance. In a further embodiment of the invention, however, these alkali metals can also be added as nitrate, borate, sulfate or in another form.
• the proportion of the total weight of the mixture to be foamed is about 1.8 - 2 * %.
• the method according to the invention is simple to carry out and can convert a current waste material into a high-quality building material, one can speak of an ideal solution to the problems at hand.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Civil Engineering (AREA)
• Materials Engineering (AREA)
• Environmental & Geological Engineering (AREA)
• Combustion & Propulsion (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Processing Of Solid Wastes (AREA)
• Containers Having Bodies Formed In One Piece (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)

Applications Claiming Priority (4)

Publications (1)

Family

ID=25812202

Family Applications (1)

Country Status (8)

Families Citing this family (4)

Family Cites Families (5)

• 1984
  • 1984-07-04 FI FI842679A patent/FI842679A/fi not_active Application Discontinuation
  • 1984-07-05 AU AU31037/84A patent/AU3103784A/en not_active Abandoned
  • 1984-07-05 EP EP84902705A patent/EP0148915A1/de not_active Withdrawn
  • 1984-07-05 WO PCT/EP1984/000204 patent/WO1985000361A1/de not_active Application Discontinuation
  • 1984-07-10 NO NO842809A patent/NO842809L/no unknown
  • 1984-07-10 DK DK337484A patent/DK337484A/da not_active Application Discontinuation
  • 1984-07-10 MX MX20196484A patent/MX172618B/es unknown
  • 1984-07-11 IT IT2183084A patent/IT1237347B/it active

Non-Patent Citations (1)

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