EP0397649A1 - Method for improving the concrete-technical properties of fly ash - Google Patents
Method for improving the concrete-technical properties of fly ashInfo
- Publication number
- EP0397649A1 EP0397649A1 EP88907697A EP88907697A EP0397649A1 EP 0397649 A1 EP0397649 A1 EP 0397649A1 EP 88907697 A EP88907697 A EP 88907697A EP 88907697 A EP88907697 A EP 88907697A EP 0397649 A1 EP0397649 A1 EP 0397649A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- ash
- fractions
- weight
- additive
- concrete
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000000034 method Methods 0.000 title claims abstract description 14
- 239000010881 fly ash Substances 0.000 title claims abstract description 9
- 239000002956 ash Substances 0.000 claims abstract description 39
- 239000000654 additive Substances 0.000 claims abstract description 11
- 230000000996 additive effect Effects 0.000 claims abstract description 11
- 239000003546 flue gas Substances 0.000 claims abstract description 8
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 4
- 229920001732 Lignosulfonate Polymers 0.000 claims abstract description 4
- 239000002245 particle Substances 0.000 claims abstract description 4
- 239000004449 solid propellant Substances 0.000 claims abstract description 3
- 235000002918 Fraxinus excelsior Nutrition 0.000 claims description 11
- 238000000926 separation method Methods 0.000 claims description 6
- 239000004117 Lignosulphonate Substances 0.000 claims description 3
- 230000000717 retained effect Effects 0.000 claims description 2
- 238000002485 combustion reaction Methods 0.000 abstract description 10
- 238000001914 filtration Methods 0.000 abstract description 3
- 238000000605 extraction Methods 0.000 abstract 1
- 238000011144 upstream manufacturing Methods 0.000 abstract 1
- 230000000694 effects Effects 0.000 description 3
- 239000003245 coal Substances 0.000 description 2
- 238000012216 screening Methods 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000005188 flotation Methods 0.000 description 1
- 235000019357 lignosulphonate Nutrition 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000003415 peat Substances 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
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
-
- 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 present invention concerns a method for improving the properties of fly ash produced in the burn ⁇ ing of solid fuels, so as to make the ash better suitable for an additive for concrete.
- the fly ash is usually re ⁇ moved from the flue gases of a combustion plant by means of electric filters or other suitable filter and separa ⁇ tion apparatuses.
- the ash separated in this way, in par ⁇ ticular the ash produced on combustion of coal, has been used as an additive for concrete, partly to substitute for the binder material in concrete.
- the fly ash also includes fractions that reduce the effect of the ad ⁇ vantageous • fractions when used in concrete and may even suppress said effects completely.
- a particular problem has been the variation of the proportion of the harmful frac ⁇ tions in relation to the advantageous fractions, which va ⁇ riation results, e.g., from the operating conditions of the combustion plant. The variations may be considerable even within one combustion plant, but in particular ashes obtained from different combustion plants cause inpredict- able problems when they are used for concrete products to ⁇ gether.
- a coarse fraction of the ash is separated from the ashes so that in the ash to be recovered, at the maximum, approximately 50 % of the weight of the ashes consist of a fraction that is retained on a screen of 45 ⁇ m, and the recovered ash is divided into at least two fractions of different grades of coarse ⁇ ness, to which Na- or Ca-lignosulphonate is added at the rate of about 0.1 to 2.5 % of the weight of the ash so that the total quantity of the addition is distributed among the ash fractions of different grades of coarseness substantially at a weight ratio proportional to their average particle sizes.
- the fol ⁇ lowing procedure has proved the simplest one.
- a coarse fraction is removed from the flue gas prior to the electric filtration so that the ash separated at the electric filters yields a screening result, wherein the
- the method of the invention has proved partic ⁇ ularly suitable for the treatment of fly ash produced on combustion of coal, but it is also suitable for the treat ⁇ ment of ash produced on combustion of peat as well as on combustion of bituminous shale, when the ash is processed so as to make it suitable for an additive for concrete.
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Ceramic Engineering (AREA)
- Combustion & Propulsion (AREA)
- Civil Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
- Solid Fuels And Fuel-Associated Substances (AREA)
Abstract
Procédé permettant d'améliorer les propriétés techniques des cendres volantes utilisées dans le béton et produites lors de la combustion de combustibles solides puis séparées des gaz de fumée. Selon la présente invention, les cendres volantes subissent une extraction de la fraction grossière, de sorte qu'elles contiennent, au maximum, environ 50 % en poids d'une fraction qui subsiste sur un tamis de 45 mum. Les cendres restantes sont divisées en au moins deux fractions de différents degrés de grossièreté, auxquelles on ajoute du lignosulfonate de Na ou Ca à raison d'environ 0,1 à 2,5 % en poids, après quoi le dosage est réparti parmi les différentes fractions selon un rapport en poids sensiblement proportionnel à leurs granulométries moyennes. Ce procédé est particulièrement approprié pour être utilisé dans le cadre de la filtration électrique de gaz de fumée, auquel cas l'additif peut être ajouté au flux de gaz de fumée après élimination de la fraction grossière en amont des filtres électriques.Process for improving the technical properties of fly ash used in concrete and produced during the combustion of solid fuels and then separated from the flue gases. According to the present invention, the fly ash undergoes an extraction of the coarse fraction, so that they contain, at most, approximately 50% by weight of a fraction which remains on a sieve of 45 mm. The remaining ash is divided into at least two fractions of different degrees of coarseness, to which is added Na or Ca lignosulfonate in an amount of about 0.1 to 2.5% by weight, after which the dosage is divided among the different fractions according to a weight ratio substantially proportional to their average particle sizes. This process is particularly suitable for use in the context of the electrical filtration of flue gases, in which case the additive can be added to the flue gas flow after removal of the coarse fraction upstream of the electric filters.
Description
Method for improving the concrete-technical properties of fly ash
The present invention concerns a method for improving the properties of fly ash produced in the burn¬ ing of solid fuels, so as to make the ash better suitable for an additive for concrete. The fly ash is usually re¬ moved from the flue gases of a combustion plant by means of electric filters or other suitable filter and separa¬ tion apparatuses. The ash separated in this way, in par¬ ticular the ash produced on combustion of coal, has been used as an additive for concrete, partly to substitute for the binder material in concrete.
It has, however, proved problematic to bring out the favourable properties of the ash, as the fly ash also includes fractions that reduce the effect of the ad¬ vantageous•fractions when used in concrete and may even suppress said effects completely. A particular problem has been the variation of the proportion of the harmful frac¬ tions in relation to the advantageous fractions, which va¬ riation results, e.g., from the operating conditions of the combustion plant. The variations may be considerable even within one combustion plant, but in particular ashes obtained from different combustion plants cause inpredict- able problems when they are used for concrete products to¬ gether.
As is well known, attempts have been made to eliminate these problems by means of various treatments of the ash, such as by fractioning the ashes by screening, cyclone separation, flotation, and magnetic methods.
Thereat, it has, however, been necessary to re¬ move most of the ashes (from the recovered ashes, the pro¬ portion of powder that passes through a 45 \_m screen is about 99 per cent) to achieve usable concrete-technical properties with the remaining fraction. This results in high costs of the ashes in the form of separation work and large-scale separation equipment, and correspondingly in
low proportion of the usable ash of the total quantity of ashes, whereby the profitability and even the quantity of available usable ash have imposed restrictions on rational utilization of the ashes.
By means of the operation of the present inven¬ tion, a substantial improvement has been provided for said problems.
According to the invention, it has been dis¬ covered that it is sufficient if a coarse fraction of the ash is separated from the ashes so that in the ash to be recovered, at the maximum, approximately 50 % of the weight of the ashes consist of a fraction that is retained on a screen of 45 μm, and the recovered ash is divided into at least two fractions of different grades of coarse¬ ness, to which Na- or Ca-lignosulphonate is added at the rate of about 0.1 to 2.5 % of the weight of the ash so that the total quantity of the addition is distributed among the ash fractions of different grades of coarseness substantially at a weight ratio proportional to their average particle sizes.
In particular in respect of the amounts of addi¬ tion of lignosulphonate, surprising results have been ob¬ tained in so far as the results aimed at were obtained with quite a small quantity of additive, which said result is obviously attributable to a "pickling effect" produced by the additive on the ash particles in the method of the invention.
In the application of the additive, it is pos¬ sible to use two alternative procedures, depending on the construction of the flue gas cleaning equipment of the combustion plant.
In connection with electric filtration, the fol¬ lowing procedure has proved the simplest one. A coarse fraction is removed from the flue gas prior to the electric filtration so that the ash separated at the electric filters yields a screening result, wherein the
The figure has been drafted on the basis of. standard concrete tests, wherein the aim has been a 28-day compression strenght of about 60 MN/m^.
The method of the invention has proved partic¬ ularly suitable for the treatment of fly ash produced on combustion of coal, but it is also suitable for the treat¬ ment of ash produced on combustion of peat as well as on combustion of bituminous shale, when the ash is processed so as to make it suitable for an additive for concrete.
Claims
1. Method for improving the concrete-technical properties of fly ash produced in the burning of solid fuel and separated from the flue gases, c h a r ¬ a c t e r i z e d in that a coarse fraction of the ash is separated from the ashes so that, in the ash to be re¬ covered, at the maximum, approximately 50 % of the weight of the ashes consist of a fraction that is retained on a screen of 45 μm, that the recovered ash is divided into at least two fractions of different grades of coarseness, and that Na- or Ca-lignosulphonate is added to the re¬ covered ash fractions at the rate of about 0.1 to 2.5 % of the weight of the ash so that the overall quantity of the additive is distributed among the ash fractions of diffe¬ rent grades of coarseness substantially at a weight ratio proportional to their average particle sizes.
2. Method as claimed in claim 1, c h a r ¬ a c t e r i z e d in that the quantity of additive ad¬ ministered to the ash is 0.1 to 1 %, advantageously 0.1 to 0.5 % of the weight of the ash.
3. Method as claimed in claim 1 or 2, c h a r ¬ a c t e r i z e d in-that the additive is added to frac¬ tions formed in connection with the separation of the ash.
4. Method as claimed in claim 1 or 2, c h a r ¬ a c t e r i z e d in that the additive is added to the flue gas flow after the separation of the coarse ash frac¬ tion, so as to be separated in subsequent separation sta¬ ges along with the ash fractions.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI873768A FI873768A (en) | 1987-08-31 | 1987-08-31 | FOERFARANDE FOER ATT FOERBAETTRA DE BETONGTEKNISKA EGENSKAPERNA HOS FLYGASKA FRAON STENKOLSFOERBRAENNING. |
| FI873768 | 1987-08-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP0397649A1 true EP0397649A1 (en) | 1990-11-22 |
Family
ID=8524971
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP88907697A Withdrawn EP0397649A1 (en) | 1987-08-31 | 1988-08-31 | Method for improving the concrete-technical properties of fly ash |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0397649A1 (en) |
| DK (1) | DK51290D0 (en) |
| FI (1) | FI873768A (en) |
| WO (1) | WO1989001917A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL1016972C2 (en) * | 2000-12-22 | 2002-06-25 | Duos B V | Screening method for separating fine particles, especially fly ash, using screen with bed of fine particles on top |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1165897A (en) * | 1965-10-05 | 1969-10-01 | John Mchenry | Pellet-Hardening Method |
| DE3411010A1 (en) * | 1983-03-26 | 1984-09-27 | Herbert Keller GmbH & Co, 4600 Dortmund | Use of flue dust as additive for concrete |
-
1987
- 1987-08-31 FI FI873768A patent/FI873768A/en not_active IP Right Cessation
-
1988
- 1988-08-31 WO PCT/FI1988/000139 patent/WO1989001917A1/en not_active Application Discontinuation
- 1988-08-31 EP EP88907697A patent/EP0397649A1/en not_active Withdrawn
-
1990
- 1990-02-27 DK DK51290A patent/DK51290D0/en not_active Application Discontinuation
Non-Patent Citations (1)
| Title |
|---|
| See references of WO8901917A1 * |
Also Published As
| Publication number | Publication date |
|---|---|
| WO1989001917A1 (en) | 1989-03-09 |
| FI873768A0 (en) | 1987-08-31 |
| DK51290A (en) | 1990-02-27 |
| DK51290D0 (en) | 1990-02-27 |
| FI873768A (en) | 1989-03-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
| 17P | Request for examination filed |
Effective date: 19900227 |
|
| AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AT BE CH DE FR GB IT LI LU NL SE |
|
| STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
| 18D | Application deemed to be withdrawn |
Effective date: 19910301 |