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US20040129180A1 - Carbon scavenger fly ash pretreatment method - Google Patents

Carbon scavenger fly ash pretreatment method Download PDF

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Publication number
US20040129180A1
US20040129180A1 US10/628,185 US62818503A US2004129180A1 US 20040129180 A1 US20040129180 A1 US 20040129180A1 US 62818503 A US62818503 A US 62818503A US 2004129180 A1 US2004129180 A1 US 2004129180A1
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US
United States
Prior art keywords
fly ash
air entrainment
carbon
ash
aromatic carboxylic
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.)
Abandoned
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US10/628,185
Inventor
Bruce Boggs
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Individual
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Individual
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Priority to US10/628,185 priority Critical patent/US20040129180A1/en
Publication of US20040129180A1 publication Critical patent/US20040129180A1/en
Abandoned legal-status Critical Current

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Classifications

    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B18/00Use 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
    • C04B18/04Waste materials; Refuse
    • C04B18/06Combustion residues, e.g. purification products of smoke, fumes or exhaust gases
    • C04B18/08Flue dust, i.e. fly ash
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02WCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00Technologies for solid waste management
    • Y02W30/50Reuse, recycling or recovery technologies
    • Y02W30/91Use of waste materials as fillers for mortars or concrete
    • YGENERAL 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
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S106/00Compositions: coating or plastic
    • Y10S106/01Fly ash

Definitions

  • Coal fired power plants generate fly ash from the combustion of pulverized coal, or combinations of pulverized coal and other carbonaceous supplemental fuels such as petroleum coke, woodbark, charcoal, wood, residual fibers, etc.
  • the fly ash is captured in the power plant's emission control devices, such as by electrostatic precipitators and baghouses.
  • the principal composition of fly ash includes an inert mineral fraction consisting primarily of ferro-alumino-silicate glass and residual unburned carbon from coal and/or other supplemental fuels.
  • the inert mineral fraction of fly ash is a pozzolan, which makes fly ash an acceptable mineral admixture for use in Portland cement concrete.
  • the fly ash itself includes the devolatized mineral matter which has been trapped or loosely associated with the coal as well as incombustible components and elements of the coal and/or of the supplemental fuels.
  • the fly ash contains carbon rich particles which have not been completely combusted, usually due to the inefficiency of the boiler design or related conditions.
  • fly ash in Portland cement concrete are set out in ASTM #C618.
  • This specification limits the loss-on-ignition (LOI) content of fly ash pozzolan to less than 6%.
  • the LOI value of fly ash in generally equal to the percent by weight of the unburned carbon content of the fly ash. This carbon content can vary from as little as about 0.5% up to 20% or more of the weight of the total fly ash product.
  • a good quality fly ash should contain less than 1% carbon but, in any case, no more than 4% carbon.
  • a high carbon fly ash as a pozzolanic mixture has a detrimental impact upon the quality of concrete.
  • the presence of carbon reduces air entrainment, which, in many locations, is the only real protection that concrete has against freeze-thaw/wet-dry conditions. Therefore, the lower the carbon content, the better the concrete mix is from an air entrainment perspective.
  • the presence of carbon also increases water requirements, reduces pozzolanic reactivity, and degrades the appearance of finished concrete surface. Thus, carbon negatively affects the strength, durability, and aesthetic appearance of concrete. Therefore, the lower the carbon content in any fly ash, the better the fly ash as a concrete admixture.
  • air entrainment agents are added to the concrete mix in order to desirably increase the amount of small air bubbles that are formed during mixing.
  • carbon reduces the ability of these agents to operate efficiently.
  • the present invention is directed to a chemical treatment that may be applied to the high carbon content fly ash either prior to or concurrent with its mixing with the other concrete components.
  • aromatic carboxylic acid or hydroxy substituted aromatic carboxylic acid is added to a quantity of fly ash to reduce air entraining chemical demand.
  • aromatic carboxylic acids include benzoic, phthalic, isophthalic, and terephthalic acids and their salts. Included in the hydroxy substituted aromatic carboxylic acids found effective are salicylic acid, m-hydroxybenzoic acid, and p-hydroxybenzoic acid and their salts.
  • air neutral agents must be used to improve the air entrainment properties of the carbon containing ash. That is, these chemical carbon scavengers should not significantly promote air entrainment by themselves or retard air or bubble formation. However, these scavengers should be adsorbed onto the carbon, thus satisfying the affinity or appetite that the carbon otherwise would have for the AEAs.
  • Pretreatment of the fly ash by the chemical carbon scavenger may be performed simultaneously with other chemical treatments applied to the ash, such as those that may be used to reduce the NH 3 content of the ash.
  • exemplary chemical carbon scavengers have been found to include the aromatic carboxylic acids such as benzoic, phthalic, isophthalic, and terephthalic acids and their salts and the hydroxy substituted aromatic carboxylic acids such as salicylic acid, m-hydroxybenzoic acid and p-hydroxybenzoic acid and their salts.
  • salicylic acid and its salts may be preferred, with lithium salicylate perhaps the most preferred at present. It has been noted that treatment of 100 g of ash with 0.07 g lithium salicylate has achieved at least 30% reduction of air entraining chemical demand. Further, this particular carbon scavenger did not exhibit either air entrainment or suppression. It is anticipated that treatment dosages of these scavengers will range from 0.01 g to 100 g chemical carbon scavenger based on 100 g of fly ash.

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  • 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)

Abstract

A method for pretreatment of a quantity of fly ash for use in a cementitious composition containing an air entrainment agent. An effective amount of an aromatic carboxylic acid or its salts is added to the fly ash to satiate unburned carbon in the ash. The treatment with the aromatic carboxylic acid (or hydroxy substituted aromatic carboxylic acid or its salts) does not significantly promote or retard the air entrainment functions of the air entrainment agent.

Description

  • This application is a continuation of co-pending U.S. patent application Ser. No. 09/804,737, filed Mar. 13, 2001, which claims priority to U.S. Provisional Patent Application No. 60/188,737, filed Mar. 13, 2000.[0001]
  • BACKGROUND OF THE INVENTION
  • Coal fired power plants generate fly ash from the combustion of pulverized coal, or combinations of pulverized coal and other carbonaceous supplemental fuels such as petroleum coke, woodbark, charcoal, wood, residual fibers, etc. The fly ash is captured in the power plant's emission control devices, such as by electrostatic precipitators and baghouses. The principal composition of fly ash includes an inert mineral fraction consisting primarily of ferro-alumino-silicate glass and residual unburned carbon from coal and/or other supplemental fuels. [0002]
  • The inert mineral fraction of fly ash is a pozzolan, which makes fly ash an acceptable mineral admixture for use in Portland cement concrete. The fly ash itself includes the devolatized mineral matter which has been trapped or loosely associated with the coal as well as incombustible components and elements of the coal and/or of the supplemental fuels. In addition to such incombustible components, the fly ash contains carbon rich particles which have not been completely combusted, usually due to the inefficiency of the boiler design or related conditions. [0003]
  • Specifications for the use of fly ash in Portland cement concrete are set out in ASTM #C618. This specification limits the loss-on-ignition (LOI) content of fly ash pozzolan to less than 6%. The LOI value of fly ash in generally equal to the percent by weight of the unburned carbon content of the fly ash. This carbon content can vary from as little as about 0.5% up to 20% or more of the weight of the total fly ash product. However, for pozzolanic activity, a good quality fly ash should contain less than 1% carbon but, in any case, no more than 4% carbon. [0004]
  • A high carbon fly ash as a pozzolanic mixture has a detrimental impact upon the quality of concrete. The presence of carbon reduces air entrainment, which, in many locations, is the only real protection that concrete has against freeze-thaw/wet-dry conditions. Therefore, the lower the carbon content, the better the concrete mix is from an air entrainment perspective. The presence of carbon also increases water requirements, reduces pozzolanic reactivity, and degrades the appearance of finished concrete surface. Thus, carbon negatively affects the strength, durability, and aesthetic appearance of concrete. Therefore, the lower the carbon content in any fly ash, the better the fly ash as a concrete admixture. [0005]
  • In many cases, air entrainment agents (AEA) are added to the concrete mix in order to desirably increase the amount of small air bubbles that are formed during mixing. In these cases, carbon reduces the ability of these agents to operate efficiently. [0006]
  • SUMMARY OF THE INVENTION
  • The present invention is directed to a chemical treatment that may be applied to the high carbon content fly ash either prior to or concurrent with its mixing with the other concrete components. [0007]
  • Specifically, aromatic carboxylic acid or hydroxy substituted aromatic carboxylic acid is added to a quantity of fly ash to reduce air entraining chemical demand. Such aromatic carboxylic acids include benzoic, phthalic, isophthalic, and terephthalic acids and their salts. Included in the hydroxy substituted aromatic carboxylic acids found effective are salicylic acid, m-hydroxybenzoic acid, and p-hydroxybenzoic acid and their salts.[0008]
  • DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
  • Recent emphasis has been given to the removal of the carbon from the fly ash before utilization (i.e. mixing) of the ash component in the concrete, such as Portland cement concrete (PCC). These chemical treatments or chemical carbon scavengers must somehow satisfy the affinity of the carbon for the commonly used air-entraining agents. At the same time, the use of just any chemical is not acceptable since the chemical itself must not entrain air when the ash is used in the PCC, nor must the chemical inhibit the intended, desirable functions of the AEA. [0009]
  • Accordingly, “air neutral” agents must be used to improve the air entrainment properties of the carbon containing ash. That is, these chemical carbon scavengers should not significantly promote air entrainment by themselves or retard air or bubble formation. However, these scavengers should be adsorbed onto the carbon, thus satisfying the affinity or appetite that the carbon otherwise would have for the AEAs. [0010]
  • Pretreatment of the fly ash by the chemical carbon scavenger may be performed simultaneously with other chemical treatments applied to the ash, such as those that may be used to reduce the NH[0011] 3 content of the ash.
  • At present, exemplary chemical carbon scavengers have been found to include the aromatic carboxylic acids such as benzoic, phthalic, isophthalic, and terephthalic acids and their salts and the hydroxy substituted aromatic carboxylic acids such as salicylic acid, m-hydroxybenzoic acid and p-hydroxybenzoic acid and their salts. [0012]
  • Based upon available preliminary test data, salicylic acid and its salts may be preferred, with lithium salicylate perhaps the most preferred at present. It has been noted that treatment of 100 g of ash with 0.07 g lithium salicylate has achieved at least 30% reduction of air entraining chemical demand. Further, this particular carbon scavenger did not exhibit either air entrainment or suppression. It is anticipated that treatment dosages of these scavengers will range from 0.01 g to 100 g chemical carbon scavenger based on 100 g of fly ash. [0013]
  • Other additional candidate chemical carbon scavengers include families of dyes and multi-ring aromatics as well as some alkyl-aryl compounds. [0014]
  • Although the invention has been described with reference to a specific embodiment, this description is not meant to be construed in a limiting sense. On the contrary, various modifications of the disclosed embodiments will become apparent to those skilled in the art upon reference to the description of the invention. It is therefore contemplated that the appended claims will cover such modifications, alternatives, and equivalents that fall within the true spirit and scope of the invention. [0015]

Claims (5)

1. A method for pretreating fly ash for use in cementitious compositions containing an air entrainment agent comprising the steps of:
applying an effective amount of benzoic acid to a quantity of fly ash to satiate unburned carbon in said ash without effecting the air entrainment functions of said air entrainment agent.
2. A method for pretreating fly ash for use in cementitious compositions containing an air entrainment agent comprising the steps of:
applying an effective amount of salicylic acid to a quantity of fly ash to satiate unburned carbon in said ash without effecting the air entrainment functions of said air entrainment agent.
3. The method of claim 1 wherein said amount of benzoic acid is in the range of about 0.01 g to about 100 g for each 100 g of said fly ash.
4. The method of claim I wherein said amount of salicylic acid is in the range of about 0.01 g to about 100 g for each 100 g of said fly ash.
5. A method for pretreating fly ash for use in cementitious compositions containing an air entrainment agent comprising the steps of:
applying an effective amount of lithium salicylate to a quantity of fly ash to satiate unburned carbon in said ash without effecting the air entrainment functions of said air entrainment agent, said effective amount of lithium salicylate is about 0.07 g for each 100 g of said fly ash.
US10/628,185 2000-03-13 2003-07-28 Carbon scavenger fly ash pretreatment method Abandoned US20040129180A1 (en)

Priority Applications (1)

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Applications Claiming Priority (3)

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US18873700P 2000-03-13 2000-03-13
US09/804,737 US6599358B1 (en) 2000-03-13 2001-03-13 Carbon scavenger fly ash pretreatment method
US10/628,185 US20040129180A1 (en) 2000-03-13 2003-07-28 Carbon scavenger fly ash pretreatment method

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040144287A1 (en) * 2003-01-24 2004-07-29 Boral Material Technologies Inc. System and method for treating fly ash
US20040206276A1 (en) * 2003-01-24 2004-10-21 Handy Chemicals Limited Sacrificial agents for fly ash concrete
US7938571B1 (en) 2005-10-11 2011-05-10 Flyashdirect, Ltd. Fly ash treatment system and method of use thereof
US7942566B1 (en) 2005-10-11 2011-05-17 Flyashdirect, Ltd. Fly ash treatment system and method of use thereof
US20120227630A1 (en) * 2011-03-08 2012-09-13 Staker & Parson Companies Concrete mixtures including carbon encapsulating admixture
US8652249B2 (en) 2009-05-06 2014-02-18 Ruetgers Polymer Ltd. Amine sacrificial agents and methods and products using same
WO2014097871A1 (en) 2012-12-17 2014-06-26 株式会社ダイヤメット Starting material powder for powder metallurgy

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6599358B1 (en) * 2000-03-13 2003-07-29 Mainland Laboratory, Ltd. Carbon scavenger fly ash pretreatment method
US7976625B2 (en) * 2006-01-20 2011-07-12 Cognis Ip Management Gmbh Compounds and methods for treating fly ash
US20070204764A1 (en) * 2006-01-23 2007-09-06 Jianhua Mao Compounds and methods for reducing water content in cementitious mixtures
US20090314185A1 (en) * 2006-10-17 2009-12-24 Matrix Llc Treatment of fly ash
US7985324B2 (en) * 2006-10-17 2011-07-26 Matrix Llc Plasma treatment of fly ash from coal combustion to improve its marketability
ES3035113T3 (en) 2015-02-27 2025-08-28 Gcp Applied Tech Inc Modifying cementitious compositions using ketone alcohol oil waste

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6599358B1 (en) * 2000-03-13 2003-07-29 Mainland Laboratory, Ltd. Carbon scavenger fly ash pretreatment method

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6599358B1 (en) * 2000-03-13 2003-07-29 Mainland Laboratory, Ltd. Carbon scavenger fly ash pretreatment method

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7892349B2 (en) 2003-01-24 2011-02-22 Boral Material Technologies Inc. Sacrificial agents for fly ash concrete
US7901505B2 (en) 2003-01-24 2011-03-08 Boral Material Technologies Inc. Sacrificial agents for fly ash concrete
US7485184B2 (en) 2003-01-24 2009-02-03 Handy Chemicals Ltd. Sacrificial agents for fly ash concrete
US20090199743A1 (en) * 2003-01-24 2009-08-13 Handy Chemicals Ltd. Sacrificial Agents for Fly Ash Concrete
US20090199744A1 (en) * 2003-01-24 2009-08-13 Handy Chemicals Ltd. Sacrificial agents for fly ash concrete
US20090199742A1 (en) * 2003-01-24 2009-08-13 Handy Chemicals Ltd. Sacrificial agents for fly ash concrete
US20090258777A1 (en) * 2003-01-24 2009-10-15 Boral Material Technologies Inc. System and method for treating fly ash
US7892350B2 (en) 2003-01-24 2011-02-22 Boral Material Technologies Inc. Sacrificial agents for fly ash concrete
US20040206276A1 (en) * 2003-01-24 2004-10-21 Handy Chemicals Limited Sacrificial agents for fly ash concrete
US20040144287A1 (en) * 2003-01-24 2004-07-29 Boral Material Technologies Inc. System and method for treating fly ash
US7938571B1 (en) 2005-10-11 2011-05-10 Flyashdirect, Ltd. Fly ash treatment system and method of use thereof
US7942566B1 (en) 2005-10-11 2011-05-17 Flyashdirect, Ltd. Fly ash treatment system and method of use thereof
US8652249B2 (en) 2009-05-06 2014-02-18 Ruetgers Polymer Ltd. Amine sacrificial agents and methods and products using same
US20120227630A1 (en) * 2011-03-08 2012-09-13 Staker & Parson Companies Concrete mixtures including carbon encapsulating admixture
US8871021B2 (en) * 2011-03-08 2014-10-28 Staker & Parson Companies Concrete mixtures including carbon encapsulating admixture
WO2014097871A1 (en) 2012-12-17 2014-06-26 株式会社ダイヤメット Starting material powder for powder metallurgy
US9844811B2 (en) 2012-12-17 2017-12-19 Diamet Corporation Raw material powder for powder metallurgy

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