CA1056409A - Lime-fly ash-sulfite compositions - Google Patents

Lime-fly ash-sulfite compositions

Info

Publication number
CA1056409A
CA1056409A CA229,901A CA229901A CA1056409A CA 1056409 A CA1056409 A CA 1056409A CA 229901 A CA229901 A CA 229901A CA 1056409 A CA1056409 A CA 1056409A
Authority
CA
Canada
Prior art keywords
earth metal
alkaline earth
recited
lime
slurry
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.)
Expired
Application number
CA229,901A
Other languages
French (fr)
Inventor
Leonard J. Minnick
William C. Webster
Charles L. Smith
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Iu Technology Corp
Original Assignee
Iu Technology Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Iu Technology Corp filed Critical Iu Technology Corp
Priority to CA229,901A priority Critical patent/CA1056409A/en
Application granted granted Critical
Publication of CA1056409A publication Critical patent/CA1056409A/en
Expired legal-status Critical Current

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Classifications

    • 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
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P40/00Technologies relating to the processing of minerals
    • Y02P40/10Production of cement, e.g. improving or optimising the production methods; Cement grinding

Abstract

A B S T R A C T
Waste sulfite sludges are treated and disposed of by incorporation in hardenable compositions useful as structural materials. Such sulfite sludges may result from double alkali treatment or lime or limestone scrub-bing of sulfur oxide-containing gases, such as combustion furnace stack gases, for desulfurization thereof. After dewatering, alkaline earth metal material and a pozzolanically active waste material are added to the sludge. The resultant hardenable compositions has a solids content of 30-90%, by weight, the solids comprising 0.25 - 70% alkaline earth metal hydroxide, 0.25 - 70%
alkaline earth metal sulfite and pozzolanic material sufficient to provide pozzolanic activity equal to 10 - 88.5% fly ash.

Description

This invention relates to several improvements in the inventions previously disclosed and claimed in our Canadian patent application 186,020, filed November 16, 1973.
Briefly, the inventions disclosed and claimed in our above re-ferenced patent applications relate to methods of disposal and use of alkaline earth metal sulfite-containing scrubber sludges.
These sludges may result from lime or limestone scrubbing of sulfur oxide-containing gases, such as combustion stack gases for desulfuriza-tion thereof; the scrubber underflow comprising an aqueous suspension of alkaline earth metal sulfites. Such sludges also may be produced in the double alkali desulfurization process wherein stack gases are scrubbed with ~ -sodium, potassium or ammonium hydroxide solutions. The sludge is produced when these solutions are then treated with lime or limestone to precipitate the sulfites.
The sulfite sludges of interest in this invention may also include some sulfate compounds. These may result from incidental chemical reactions accompanying the desulfurization and scrubbing steps or they may result from specific steps intended to oxidize sulfites to sulfates for some specific pur-pose such as to improve dewatering characteristics.
Generally, these aqueous sludges are dewatered and treated, as required, with lime and/or fly ash to produce novel cementitious compositions having from 30 to 90%, by weight, solids, the solids comprising 0.25-70%, by weight, alkaline earth metal sulfite, 0~25-70%, by weight, alkaline earth metal hydroxide and 10-99.5% fly ash. This hardenable material may be used as structural fill, road base, or in the formation of synthetic aggregate.
The sludge itself, prior to treatment, may provide some or all of the necessary alkaline earth metal hydroxide and/or fly ash. Normally, a stoichiometric excess of Iime or limestone used in the scrubbing operation and the residual or remaining alkaline earth metal hydroxide is then available for reaction in the present invention. Similarly, fly ash may not be separat-ed from the stack gases prior to the scrubber operation and this fly ash is available for reaction.
The further improvements which are the subject of the present application are in the use of other waste materials to replace part or all of the lime and fly ash additions heretoore specifically disclosed and used.
The supplementary or complementary materials which may be used in these hardenable compositions, in accordance with the present invention, include Portland cement, high alumina cement, waste lime, lime kiln dust, partially calcined lime, cement kiln dust, BOF waste dust, or slag, coal mine refuse or tailings, "red mud" resulting from the chemical reduction of bauxite, alum waste, bottom ash and any highly amorphous siliceous or alumino-siliceous incineration residue, such as that from petroleum refinery waste incineration.
In some cases, these alternative waste materials are flocculent slurries with a high proportion of physically associated water. As the solids in these slurries react, this water becomes available. m e propor-tion of such waste slurries in the treatment mix of the present invention may be limited by the water content thus contributed to the mix. It should be noted that these supplementary or complementary materials may provide reactants for the pozzolanic cementitious reaction, or they may act as ag-gregate or filler material. They may also contribute supplementary cementi-tious activity, as in the case of Portland or alumina cement. Waste lime, partially calcined lime, cement kiln dust and sOF waste dust are active sources of alkaline earth metal hydroxides for the reaction upon which the present invention depends.
These materials, in combination with those previously disclosed or in combination with other sources of alkaline earth metal hydroxides or pozzo-lanic activity may be used in treating sulfite sludges to produce hardenable materials there from, these hardenable compositions being defined as here-tofore with the exception that the 10-99.5% 1y ash content in the sludge .!.~

composition solids may consist of fly ash or equivalent amounts of other materials having pozzolanic activity, the equivalent amount being de~ermined by ASTM Test Method C-618, "Pozzolanic Activity Index - With Lime".
Thus, the amount of a highly amorphous siliceous incinerator waste residue, such as that from petroleum refinery waste incineration, providing a pozzolanic activity, in accordance with the foregoing test, corresponding ~ -to that of 10-99.5% fly ash, may be incorporated in the compositions of the present invention and used in the methods of the present invention.
Other waste materials as described above may also be incorporated in place of some or all of the required fly ash content, dependent upon the pozzolanic activity thereof in accordance with the test as described above.
Similarly, the various above referenced waste materials including alkaline earth metal hydroxides or hydratable alkaline earth metal oxides may also be incorporated to the extent of their molar equivalency with 0.25-70%
alkaline earth metal hydroxide.
Por a better understanding of this invention, reference is made to the following illustrative examples of this invention and particularly the sludge treatment processes hereof and the hardenable and hardened compositions resulting therefrom.

Example l A sulfite scrubber sludge, produced by limestone scrubbing of the stack gases in a full scale pulverized coal burning power generation unit was dewatered to a solids content of 50%, by weight. The solids composition of this sludge consisted of:
35% CaCO3 15% CaSO3 1/2 H2O
10% CaSO4-H20 40% Fly Ash Various mixes of this sludge with Portland and alumina cement were tested, with these added cements comprising up to 40%, by weight, of the resultant sludge solids. The development of strength, as indicated by Pene-tration Resistance,is shown by the test results listed in Table 1.

: :
. ' ~`~ :~ og 880 a ~
. ~ ~ 8 ~ ~ 8 '~ ~ ':' ~ :~ I ~ 8 8 8 8 o :

:~ I ~ ~ g o o , .

~1 E~ ~ I 1 8 8 g ~ n ~'~ 8 ~ O, 8 ~ I u , 0, 1 1 ~ e ~, ~888~ *

_ 4 --.

~0~6409 Example 2 Sludge produced in a double alkali treatment process for desul-furizing stack gases was dewatered to a solids content of 62%, by weight. Fly ash from the same power generating unit in which the stack gases were pro-duced was added to the sludge in an amount equal to 150% of the total weight of the sludge sample. In this particular sample, in view of the residual calcium hydroxide in the fly ash and in the sludge, no additional alkaline earth metal material was added.
This prepared mixture was then permitted to harden and tested for penetration resistance with results as listed in Table 2.
Table 2 Penetration Resistance Age of Test Resistance ~in PSI) 1 week 2,080
2 weeks 24,800
3 weeks 28,800 5 weeks 44,800 Examples 3 and 4 Lime kiln dust (partially calcined limestone) was admixed with a sulfite scrubber sludge from a pilot scrubber in a full scale power generating plant. This sludge consisted of 60% (by weight) solids, the solids consisting of 50% calcium sulfite, 40% fly ash, 8% calcium sulfate and 2% free lime.
Blast furnace slag was admixed with synthetic sulfite scrubber sludge (by weight~ 60% solids, solids consisting of 45% calcium sulfite, 35% fly ash, 10%
calcium sulfate, 5% calcium carbonate, and 5% calcium hydroxide).
These mixtures were permitted to harden, as indicated and tested for penetration resistance with results as indicated in Tables 3 and 4.

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O O O O
OOOO
_~ ~ ~ N

a) ~ o o o o ~ ¦ ~ ~ ~r N

~ O O O O
~ 0 ~0, C ~o .

~ 000O ~ , D ,_1 ~ ~1 ,1 - h _ ~11 n~,~ ~

'-~
~1 , '~ , .~ o C~ U~

~056409 Example 5 Sludge from the same source as that in Example 3 (in which lime containing approximately 5%, by weight, magnesium oxide, was used in the scrubber) was dewatered to 55% solids. The composition of the sludge solids, after the addition of fly ash was as follows: (%, by weight):
1-3% Ca(OH)2 42-44% CaS03 1/2H20 8-9% CaS04-2H20 40% Fly Ash 5% CaC03 1-2% MgS03-1/2H20 ~ MgS04 7H2 High calcium lime and a typical type I cement was added to various mixes of this sludge with penetration resistance test results, after curing at 100F. in a moist atmosphere as listed in Tables 5 and 6.

~ o g g 3 o~, ~

~1 I ~`3 N t~

h 3 o o o o .~ , ~ ~ ~

_ ,~, o~

~ g g .~ ,, -- 10 _ Example 6 A sludge as described above in Example 1 tsolids content, 50%) was treated with dolomitic monohydrated lime and a typical Type I Cement.
Samples were cured in a moist atmosphere at 100 F, with test results as shown in Table 7.

~ ~ ,, ,ol g .~ ,, ~ ~

The foregoing is a description of this invention with reference to specific embodiments, materials and examples. It should be understood, however, that this invention is not limited thereto and the appended claims are intended to be construed to encompass the various modifications and varia-tions of the invention which may be made by those skilled in the art without departing from the true spirit and scope of the present invention.

Claims (17)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of producing a hardenable, structural cementitious composition, said method consisting of treating a slurry produced in a stack gas scrubber wherein sulfur oxide-containing stack gases are desulfur-ized by chemical treatment with materials including lime or limestone, the resultant scrubber slurry comprising an aqueous suspension of alkaline earth metal sulfite and alkaline earth metal oxide, hydroxide, sulfate or carbonate, said slurry treatment consisting of dewatering said slurry and adding to said dewatered slurry a pozzolanically active waste material and alkaline earth metal material as required, such that the final composition of the solids in said treated slurry comprises 0.25 to 70 weight % alkaline earth metal hydroxide, 0.25 to 70 weight % alkaline earth metal sulfite, and pozzolanically active waste material providing pozzolanic activity equal to 10 to 99.5 weight % fly ash determined by ASTM Test C-618, the resultant composition having a solids content of 30 - 90 %,by weight, in water, the water and the solids being present in the hardenable composition in relative amounts adapted to harden the composition cementitiously.
2. A method, as recited in claim 1, wherein said pozzolanically ac-tive waste material is a highly amorphous siliceous or alumino-siliceous incineration residue.
3. A method, as recited in claim 1, wherein said alkaline earth metal material added to said slurry is selected from the group consisting of waste lime, partially calcined lime, lime kiln dust, cement kiln dust, and BOF waste dust.
4. A method, as recited in claim 3, wherein said pozzolanically active waste material is fly ash.
5. A method, as recited in claim 1, wherein said alkaline earth metal material is lime.
6. A method, as recited in claim 1, wherein said dewatered slurry composition is treated by the further admixture therewith of additives from the group consisting of Portland cement, high alumina cement, BOF slag, bottom ash, coal-mine tailings, alum waste, and "red mud".
7. A method, as recited in claim 1, wherein said final composition further includes alkaline earth metal sulfate, said sulfite comprising at least 10%, by weight, of the combined total weight of sulfate and sulfite.
8. A method, as recited in claim 1, wherein said treated slurry has a solids content of 30 - 60 weight %.
9. A method, as recited in claim 1, wherein said treated slurry has a solids content of 50 - 90 weight %.
10. A method for disposing of the slurry product of a scrubber in which sulfur oxide-containing gases are desulfurized by chemical treat-ment with materials including lime or limestone, said method comprising de-watering said slurry product, and treating said dewatered slurry product by adding alkaline earth metal material and a pozzolanically active waste material as required, to produce a water suspension of 30 - 90% solids in water, by weight, said solids including 0.25 - 70 weight % alkaline earth metal hydroxide, 0.25 - 70 weight % alkaline earth metal sulphite, and pozzolanically active waste material in an amount sufficient to provide pozzolanic activity equal to 10 - 99.5 weight % fly ash determined by ASTM
Test C-618, the water and the solids being present in the suspension in re-lative amounts adapted to harden the suspension cementitiously, placing said suspension in an open area and permitting said suspension to harden cemen-titiously under atmospheric conditions.
11. A method, as recited in claim 10, wherein said desulfurization involves scrubbing said stack gases with a solution of sodium, potassium or ammonium hydroxide and then treating said solution with lime or limestone.
12. A method, as recited in claim 10, wherein said sulfur oxide-containing gases are produced in a pulverized coal-burning combustion unit, said slurry also including fly ash from said unit.
13. A method, as recited in claim 10, wherein said pozzolanically active waste material is a highly amorphous siliceous or alumino-siliceous incineration residue.
14. A method, as recited in claim 10, wherein said alkaline earth metal material added to said slurry is selected from the group consisting of waste lime, partially calcined lime, lime kiln dust, cement kiln dust, and BOF waste dust.
15. A method, as recited in claim 14, wherein said pozzolanically active waste material is fly ash.
16. A method, as recited in claim 10, wherein said alkaline earth metal material is lime.
17. A method, as recited in claim 10, wherein said suspension is treated by the further admixture therewith of additives from the group con-sisting of Portland cement, high alumina cement, BOF slag, bottom ash, coal-mine tailings, alum waste, and "red mud".
CA229,901A 1975-06-23 1975-06-23 Lime-fly ash-sulfite compositions Expired CA1056409A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CA229,901A CA1056409A (en) 1975-06-23 1975-06-23 Lime-fly ash-sulfite compositions

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CA229,901A CA1056409A (en) 1975-06-23 1975-06-23 Lime-fly ash-sulfite compositions

Publications (1)

Publication Number Publication Date
CA1056409A true CA1056409A (en) 1979-06-12

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Application Number Title Priority Date Filing Date
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Country Link
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6402833B1 (en) 2000-07-13 2002-06-11 Lafarge Canada Inc. Binder for mine tailings
US7837412B2 (en) 2006-02-15 2010-11-23 Lafarge Canada Inc. Binder for mine tailings, alluvial sand and the like

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6402833B1 (en) 2000-07-13 2002-06-11 Lafarge Canada Inc. Binder for mine tailings
US7837412B2 (en) 2006-02-15 2010-11-23 Lafarge Canada Inc. Binder for mine tailings, alluvial sand and the like
US8177908B2 (en) 2006-02-15 2012-05-15 Lafarge Canada Inc. Binder for mine tailings, alluvial sand and the like

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