US20210238090A1 - Composite mineralizers/fluxes for the production of alite/calcium sulfoaluminate clinkers - Google Patents
Composite mineralizers/fluxes for the production of alite/calcium sulfoaluminate clinkers Download PDFInfo
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- US20210238090A1 US20210238090A1 US17/164,401 US202117164401A US2021238090A1 US 20210238090 A1 US20210238090 A1 US 20210238090A1 US 202117164401 A US202117164401 A US 202117164401A US 2021238090 A1 US2021238090 A1 US 2021238090A1
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- United States
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- csa
- cement clinker
- clinker
- cement
- alumina
- Prior art date
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- BCAARMUWIRURQS-UHFFFAOYSA-N dicalcium;oxocalcium;silicate Chemical compound [Ca+2].[Ca+2].[Ca]=O.[O-][Si]([O-])([O-])[O-] BCAARMUWIRURQS-UHFFFAOYSA-N 0.000 title claims description 27
- 239000011575 calcium Substances 0.000 title claims description 12
- 229910052791 calcium Inorganic materials 0.000 title claims description 12
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 title claims description 11
- 238000004519 manufacturing process Methods 0.000 title description 18
- 230000004907 flux Effects 0.000 title description 5
- 239000002131 composite material Substances 0.000 title description 2
- 239000004568 cement Substances 0.000 claims abstract description 88
- 239000000203 mixture Substances 0.000 claims abstract description 82
- 229910001634 calcium fluoride Inorganic materials 0.000 claims abstract description 31
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims abstract description 29
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 26
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 25
- 238000010304 firing Methods 0.000 claims abstract description 23
- 229910001570 bauxite Inorganic materials 0.000 claims abstract description 15
- 239000010881 fly ash Substances 0.000 claims abstract description 14
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 44
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 25
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 claims description 19
- 229910052593 corundum Inorganic materials 0.000 claims description 12
- 239000000377 silicon dioxide Substances 0.000 claims description 12
- 229910001845 yogo sapphire Inorganic materials 0.000 claims description 12
- 229910052681 coesite Inorganic materials 0.000 claims description 9
- 229910052906 cristobalite Inorganic materials 0.000 claims description 9
- -1 fluoride compound Chemical class 0.000 claims description 9
- 229910052682 stishovite Inorganic materials 0.000 claims description 9
- 229910052905 tridymite Inorganic materials 0.000 claims description 9
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 claims description 7
- 239000005995 Aluminium silicate Substances 0.000 claims description 5
- 235000012211 aluminium silicate Nutrition 0.000 claims description 5
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 abstract description 22
- 229910000859 α-Fe Inorganic materials 0.000 description 25
- 238000000034 method Methods 0.000 description 22
- 230000015572 biosynthetic process Effects 0.000 description 15
- 239000012071 phase Substances 0.000 description 15
- 229910001844 ye'elimite Inorganic materials 0.000 description 13
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 12
- 235000011941 Tilia x europaea Nutrition 0.000 description 12
- 238000007792 addition Methods 0.000 description 12
- 239000004571 lime Substances 0.000 description 12
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 10
- 239000002994 raw material Substances 0.000 description 10
- 229910052925 anhydrite Inorganic materials 0.000 description 9
- 239000000463 material Substances 0.000 description 9
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 8
- 239000008188 pellet Substances 0.000 description 8
- 229910052918 calcium silicate Inorganic materials 0.000 description 7
- JHLNERQLKQQLRZ-UHFFFAOYSA-N calcium silicate Chemical compound [Ca+2].[Ca+2].[O-][Si]([O-])([O-])[O-] JHLNERQLKQQLRZ-UHFFFAOYSA-N 0.000 description 7
- 235000012241 calcium silicate Nutrition 0.000 description 7
- 229910052602 gypsum Inorganic materials 0.000 description 7
- 239000010440 gypsum Substances 0.000 description 7
- 238000002844 melting Methods 0.000 description 7
- 230000008018 melting Effects 0.000 description 7
- 239000004570 mortar (masonry) Substances 0.000 description 7
- 235000019738 Limestone Nutrition 0.000 description 6
- 229910002092 carbon dioxide Inorganic materials 0.000 description 6
- 239000006028 limestone Substances 0.000 description 6
- 239000011230 binding agent Substances 0.000 description 5
- 230000007246 mechanism Effects 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 239000004927 clay Substances 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 239000010802 sludge Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 238000003991 Rietveld refinement Methods 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 3
- 239000002956 ash Substances 0.000 description 3
- XFWJKVMFIVXPKK-UHFFFAOYSA-N calcium;oxido(oxo)alumane Chemical compound [Ca+2].[O-][Al]=O.[O-][Al]=O XFWJKVMFIVXPKK-UHFFFAOYSA-N 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 239000007791 liquid phase Substances 0.000 description 3
- 238000005554 pickling Methods 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 2
- 239000004411 aluminium Substances 0.000 description 2
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 2
- 229910021502 aluminium hydroxide Inorganic materials 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 2
- 239000000920 calcium hydroxide Substances 0.000 description 2
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 238000001723 curing Methods 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000009472 formulation Methods 0.000 description 2
- 239000002803 fossil fuel Substances 0.000 description 2
- 238000000265 homogenisation Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 241000196324 Embryophyta Species 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 239000011398 Portland cement Substances 0.000 description 1
- 235000015076 Shorea robusta Nutrition 0.000 description 1
- 244000166071 Shorea robusta Species 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 239000012190 activator Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 239000011411 calcium sulfoaluminate cement Substances 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003518 caustics Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910052570 clay Inorganic materials 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000004035 construction material Substances 0.000 description 1
- 229910001679 gibbsite Inorganic materials 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000002440 industrial waste Substances 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 235000021110 pickles Nutrition 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 238000000646 scanning calorimetry Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000001509 sodium citrate Substances 0.000 description 1
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 1
- 239000011410 supersulfated cement Substances 0.000 description 1
- 238000002411 thermogravimetry Methods 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
Images
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
- C04B7/00—Hydraulic cements
- C04B7/32—Aluminous cements
- C04B7/323—Calcium aluminosulfate cements, e.g. cements hydrating into ettringite
-
- 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
- C04B7/00—Hydraulic cements
- C04B7/24—Cements from oil shales, residues or waste other than slag
- C04B7/26—Cements from oil shales, residues or waste other than slag from raw materials containing flue dust, i.e. fly ash
-
- 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
- C04B7/00—Hydraulic cements
- C04B7/345—Hydraulic cements not provided for in one of the groups C04B7/02 - C04B7/34
- C04B7/3456—Alinite cements, e.g. "Nudelman"-type cements, bromo-alinite cements, fluoro-alinite cements
-
- 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
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00034—Physico-chemical characteristics of the mixtures
- C04B2111/00215—Mortar or concrete mixtures defined by their oxide composition
-
- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding
Definitions
- This document generally relates to the cement industry and, more particularly, to an alite/calcium sulfoaluminate (A/CSA) cement clinker incorporating a novel composite of mineralizers/fluxes.
- A/CSA alite/calcium sulfoaluminate
- OPC OPC
- ingredients such as limestone, marl or chalk as a source of calcium; and clay or shales as a source of silicate and alumina.
- the raw materials are ground and fired at 1450-1500° C. to obtain the OPC clinker and mixed with 5 wt. % gypsum to obtain the final OPC cement.
- the first source of CO 2 emissions is the calcination of limestone, while the second source is the combustion of fossil fuels to produce clinker at high firing temperature. This high firing temperature is necessary for the formation of alite, a high calcium demanding clinker phase, responsible for most of the strength development in OPC cement.
- novel cement clinker composition set forth herein demonstrates that an industrial by-product, a high fly ash alumina, may be used as a source of alumina and can completely replace the use of bauxite.
- Other materials of this type include aluminium dross and scrap as well as high alumina clays such as kaolin.
- a new and improved cement clinker composition defined by oxide content comprises: 42-65 wt % CaO; 5-20 wt % SiO 2 ; 10-40 wt % Al 2 O 3 ; 0.5-5 wt % Fe 2 O 3 ; and 2-13 wt % SO 3 . More specifically, the new and improved clinker composition may comprise: 50-55 wt % CaO; 9-13 wt % SiO 2 ; 20-30 wt % Al 2 O 3 ; 0.5-3 wt % Fe 2 O 3 ; and 5-10 wt % SO 3 .
- a new and improved cement clinker composition comprises between about 0.1 and 3.0 wt % fluoride compound and between about 0.5 and about 5.0 wt % Fe 2 O 3 .
- Such a composition may be fired at a temperature of between about 1150-1350° C. More preferably such a cement clinker composition is fired at temperature of between 1200-1300° C. After firing, such a composition provides between about 15 and 40 wt % alite and between about 20 and about 60 wt % calcium sulfoaluminate.
- the new and improved cement clinker composition comprises: 15-40 wt % C 3 S; 20-60 wt % C 4 A 3 ⁇ ; 5-30 wt % C 2 S; 1-10 wt % C 4 AF; and 0.4-1.0 wt % CaF 2 as present in fluorellestadite and fluormayenite clinker phases fired at 1150-1350° C. and more particularly 1200-1300° C.
- the new and improved cement clinker composition comprises: 20-35 wt % C 3 S; 40-55 wt % C C 4 A 3 ⁇ ; 10-25 wt % C 2 S; 1-4 wt % C 4 AF; and 0.6-0.8 wt % CaF 2 as present in fluorellestadite and fluormayenite clinker phases fired at 1150-1350° and more particularly 1200-1300° C.
- cement clinker composition is capable of other, different embodiments and its several details are capable of modification in various, obvious aspects all without departing from the composition as set forth and described in the following claims. Accordingly, the drawings and descriptions should be regarded as illustrative in nature and not as restrictive.
- FIG. 1 is graph of DSC/TGA (SDT) data illustrating the influence of fluorellestadite and ferrite within A/CSA clinkers.
- FIG. 2 is a bar graph of resistivity as a function of time for cement made with the new and improved clinker composition compared to commercial cements.
- FIG. 3 is a bar graph of compressive strength as a function of time for cement made with the new and improved clinker composition compared to commercial cements.
- FIG. 4 is a line graph of length change as a function of time for cement made with the new and improved clinker composition compared to commercial cements.
- A-CSA clinker combines alite (C 3 S) and calcium sulfoaluminate (CSA, ye'elimite or C 4 A 3 ⁇ ) phases. These are the phases responsible for most of the strength development in OPC and CSA cements, respectively. Until recently, A-CSA clinker was not considered practical due to the perceived incompatible coexistence of both clinker phases. Alite forms at 1450-1500° C., while CSA decomposes at 1300-1350° C.
- This document demonstrates that the use of both calcium fluoride and iron oxide in the production of A/CSA clinker reduces the melting temperature and increases the formation of alite. Previously, it was found that the presence of sulfate hinder the formation of alite, but as this document demonstrates the production of increased levels of alite (30 wt. %) with high levels of calcium sulfoaluminate (50 wt. %) in the clinker.
- This binder formulation exhibits superior mechanical properties to both commercial OPC and CSA cement, including higher compressive strength, high resistivity, and high dimensional stability.
- the new and improved cement clinker composition as defined by oxide content incorporates about 42-65 wt % CaO; about 5-20 wt % SiO 2 ; about 10-40 wt % Al 2 O 3 ; about 0.5-5 wt % Fe 2 O 3 ; and about 2-13 wt % SO 3 .
- the new and improved clinker composition incorporates about 50-55 wt % CaO; about 9-13 wt % SiO 2 ; about 20-30 wt % Al 2 O 3 ; about 0.5-3.0 wt % Fe 2 O 3 ; and about 5-10 wt % SO 3 .
- the cement clinker composition includes between about 0.1 and about 3.0 wt % fluoride compound and between about 0.5 and about 5.0 wt % Fe 2 O 3 .
- the fluoride compound may comprise, for example, calcium fluoride (CaF 2 ), pickling liquor sludge containing fluoride and the like.
- the cement clinker composition includes between about 10-35 wt % of a bauxite substitute selected from a group consisting of high fly ash alumina, aluminum dross, aluminum scrap, high alumina clays and combinations thereof.
- a bauxite substitute selected from a group consisting of high fly ash alumina, aluminum dross, aluminum scrap, high alumina clays and combinations thereof.
- high fly ash alumina means a fly ash containing at least 20 wt. % of Al 2 O 3 , and more preferably at least 40 wt. % of Al 2 O 3 .
- “high alumina clays” means a clay containing at least 10 wt. % of Al 2 O 3 , and more preferably at least 20 wt. % of Al 2 O 3 , such as kaolin compound.
- the cement clinker composition incorporates about 15-40 wt % C 3 S; about 20-60 wt % C 4 A 3 ⁇ ; about 5-30 wt % C 2 S; about 1-10 wt % C 4 AF; and about 0.4-1.0 wt % CaF 2 as present in fluorellestadite and fluormayenite clinker phases fired at about 1150-1350° C., 1200-1300° C. or 1225-1275° C.
- the cement clinker composition further includes between about 0.5-2.0 wt % Fe 2 O 3 . In one or more embodiments, that cement clinker composition also includes between about 10-35 wt % of a bauxite substitute selected from a group consisting of high fly ash alumina, aluminum dross, aluminum scrap, high alumina clays and combinations thereof.
- the new and improved cement clinker composition comprises between about 0.1 and 3.0 wt % of a fluoride compound, such as CaF 2 , pickling liquor sludge including fluoride or the like, and between about 0.5 and about 5.0 wt % Fe 2 O 3 .
- a fluoride compound such as CaF 2 , pickling liquor sludge including fluoride or the like
- Such a composition may be fired at a temperature of between about 1150-1350° C. or 1200-1300° C. More preferably such a cement clinker composition is fired at temperature of between 1225-1275° C.
- a calculated clinker composition composed of 50 wt. % alite and 50 wt. % calcium sulfoaluminate was investigated. Four compositions were tested: #1 with no additions of CaF 2 or iron oxide; #2 with addition of only CaF 2 ; #3 with addition of only iron oxide; and #4 with additions of both CaF 2 and iron oxide.
- the compositions were produced from reagent chemicals, as presented in Table 1. Fe 2 O 3 was added at a percentage of 1.3 wt. % to obtain approximately 5 wt. % of ferrite (C 4 AF) in the final clinker composition. Regarding the addition of CaF 2 , the target was to produce approximately 10 wt. % of fluorellestadite, a liquid phase.
- the calculated clinker compositions are presented in Table 2.
- A/CSA #1 to A/CSA #4 were produced by mixing the raw materials with the quantities as described in Table 1 with an additional 10 wt. % of deionized water in a mortar and pestle until a homogenized powder was obtained. A part of the powder was kept for SDT analyses. A few 28 ⁇ 7 mm pellets were formed using a load of 25000 lbs, and dried overnight in an oven at 60° C. The pellets were then fired in a box furnace, and followed the firing program: 1—heat from room temperature to 800° C. at 7.5° C./min; 2—dwell at 800° C. for 30 min; 3—heat from 800° C. to 1250° C. at 5.0° C./min; 4—dwell at 1150/1200/1250° C. for 60 min; and 5—quench rapidly in air. The clinker pellets were then crushed in a shatter box until a fine powder was obtained.
- composition A/CSA #1 without the formation of fluorellestadite or ferrite did not form any measurable alite, at all three firing temperatures. Formation of belite was constant for all three firing temperatures, at around 40 wt. %. The formation of ye′ elimite increased with the firing temperature, especially between 1150° C. and 1200° C., from 36.5 to 47.1 wt. %. Instead of forming essentially ye'elimite at 1150° C., other clinker phases were present, such as mayenite (5.2 wt. %), calcium aluminate (2.2 wt. %) and anhydrite (2.9 wt. %).
- composition A/CSA #2 (only CaF 2 added) contained a significant amount of alite when fired at 1250° C., at 21.4 wt. %, and 4.6 wt. % of free lime. At lower firing temperatures, mostly belite and ye'elimite were present, with free lime, C 11 A 7 CaF 2 , and fluorellestadite. As studied previously in other works, the addition of calcium fluoride does provide benefit in reducing the firing temperature by forming a liquid phase, fluorellestadite, at a low temperature. Fluorellestadite does contribute to the formation of alite at a low firing temperature of 1250° C.
- composition A/CSA #3 (only iron oxide added) contained a small amount of alite (3.1 wt. %), only at 1250° C.
- belite and ye'elimite are the major clinker phases present and ferrite is present at around 4.0-4.5 wt. % at all three firing temperatures.
- the free lime content does not seem to decrease significantly, even at high firing temperature of 1250° C., with a content of 8.4 wt. %.
- the clinker ferrite is known to form a liquid phase promoting the formation of alite via a flux mechanism. Recent work by Lu et al. discusses the influence of ferrite on the formation and coexistence of ye'elimite and alite.
- An A/CSA clinker was produced from 55.7 wt. % of agricultural lime, 12.3 wt. % of FGD gypsum, 31.38 wt. % of high alumina ash, and 0.62 wt. % of calcium fluoride.
- the composition is: 52.6 wt. % CaO, 11.5 wt. % SiO 2 , 25.3 wt. % Al 2 O 3 , 1.3 wt. % Fe 2 O 3 , and 7.5 wt. % SO 3 , and minor compounds.
- the raw materials used can be easily replaced with current raw materials, such as limestone, marl/clay, bauxite, aluminium dross, and pickling liquor sludge. Other raw materials can also be introduced, as long as the oxide content of the final clinker is similar to the composition described above. Similar A/CSA clinker compositions with various available raw materials are presented in Table 5. The raw materials were milled together and fired at 1250° C. for 60 minutes, and ground to a particle size d(50) of around 13-14 ⁇ m. The final clinker was analysed by XRD/Rietveld and contained: 29.6 wt. % alite (C 3 S), 9.4 wt. % belite (C 2 S), 1.5 wt.
- European standard EN 196 was followed to produce mortar samples for compressive strength, resistivity, and dimensional stability measurements. Following the production of mortar samples, the samples were stored in a 100% humidity chamber, demolded after 24 hours, and tested after 1, 7, 14, 21, 28, 56, and 91 day. At each test day, the samples were tested for resistivity with the Resipod from Proceq, for dimensional stability by measuring the length, and for compressive strength.
- the resistivity data demonstrate that the A/CSA cement exhibits much higher resistivity compared to OPC cement at all ages. Compared to CSA cement, A/CSA cement is lower initially but increases to a similar level at 91 days. Resistivity is relatable to the level of interconnected pores and in a measure of durability.
- the compressive strength data demonstrate that after one day the new and improved A/CSA cement is 2-3 times stronger than OPC and 145% stronger than CSA with A/CSA with anhydrite. For the first 14 days, A/CSA with anhydrite is the strongest.
- the mortar samples were stable compared to the commercial cements meeting all requirements, with expansion and/or shrinkage of less than 0.08%, as can be seen from FIG. 4 .
- phrases: “a unit”, “a device”, “an assembly”, “a mechanism”, “a component, “an element”, and “a step or procedure”, as used herein, may also refer to, and encompass, a plurality of units, a plurality of devices, a plurality of assemblies, a plurality of mechanisms, a plurality of components, a plurality of elements, and, a plurality of steps or procedures, respectively.
- phrases “consisting essentially of means that the stated entity or item (system, system unit, system sub-unit device, assembly, sub-assembly, mechanism, structure, component element or, peripheral equipment utility, accessory, or material, method or process, step or procedure, sub-step or sub-procedure), which is an entirety or part of an exemplary embodiment of the disclosed invention, or/and which is used for implementing an exemplary embodiment of the disclosed invention, may include at least one additional feature or characteristic” being a system unit system sub-unit device, assembly, sub-assembly, mechanism, structure, component or element or, peripheral equipment utility, accessory, or material, step or procedure, sub-step or sub-procedure), but only if each such additional feature or characteristic” does not materially alter the basic novel and inventive characteristics or special technical features, of the claimed item.
- method refers to steps, procedures, manners, means, or/and techniques, for accomplishing a given task including, but not limited to, those steps, procedures, manners, means, or/and techniques, either known to, or readily developed from known steps, procedures, manners, means, or/and techniques, by practitioners in the relevant field(s) of the disclosed invention.
- cement clinker compositions and method of making the same have been illustratively described and presented by way of specific exemplary embodiments, and examples thereof, it is evident that many alternatives, modifications, or/and variations, thereof, will be apparent to those skilled in the art.
- the cement clinker compositions described above and in the following claims may also be accurately expressed as “consisting of” rather than “comprising” the formulations indicated in the body of the following claims. Accordingly, it is intended that all such alternatives, modifications, or/and variations, fall within the spirit of, and are encompassed by, the broad scope of the appended claims.
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Abstract
Description
- This application claims priority to U.S. Provisional Patent Application Ser. No. 62/967,625 filed on Jan. 30, 2020 which is hereby incorporated by reference in its entirety.
- This document generally relates to the cement industry and, more particularly, to an alite/calcium sulfoaluminate (A/CSA) cement clinker incorporating a novel composite of mineralizers/fluxes.
- The cement industry is the third-largest consumer of industrial energy and the second-largest emitter of industrial carbon dioxide. With the global population growing every year, there is a need for further construction materials in order to meet infrastructure requirements. Ordinary Portland cement (OPC) is the most widely used type of cement material for construction purposes, and it has been estimated that the production of cement is responsible for approximately 7-8% of anthropogenic carbon dioxide emissions worldwide.
- The production of OPC requires natural resources as ingredients, such as limestone, marl or chalk as a source of calcium; and clay or shales as a source of silicate and alumina. The raw materials are ground and fired at 1450-1500° C. to obtain the OPC clinker and mixed with 5 wt. % gypsum to obtain the final OPC cement. There are two main processes in cement production responsible for the CO2 emissions. The first source of CO2 emissions is the calcination of limestone, while the second source is the combustion of fossil fuels to produce clinker at high firing temperature. This high firing temperature is necessary for the formation of alite, a high calcium demanding clinker phase, responsible for most of the strength development in OPC cement.
- For the past decades, various alternative cementitious binders with lower CO2 emissions than OPC have been proposed. These alternative binders are produced at a lower firing temperature than OPC but do not contain alite and do not perform on a par with it. They include calcium aluminate cements (CAC), belite-calcium sulfoaluminate cement (BCSA), alkali-activated materials (AAM), supersulfated cement, calcium sulfoaluminate belite ferrite cement (CSABF), etc. However, these possible alternative solutions encounter issues, ranging from loss of strength over time due to carbonation for CAC, to costly raw materials in CSAB, to highly caustic and costly activators for AAM, and special curing methods (supersulfated and other cements).
- The production of a successful commercial alternative binder should be able to seamlessly replace current commercial OPC production methods in cement plants. For example, the same rotary kilns used to produce OPC should be used to produce alternative cements but at a lower firing temperature to reduce the CO2 emissions from the decarbonation of limestone and the fossil fuels. Alternative materials to limestone should be targeted, with emphasis on industrial wastes and by-products. As an example, it has been widespread that CSA cement cannot be widely produced due to the necessity to use bauxite, an abundant but not regionally available material, making it costly. However, the novel cement clinker composition set forth herein demonstrates that an industrial by-product, a high fly ash alumina, may be used as a source of alumina and can completely replace the use of bauxite. Other materials of this type include aluminium dross and scrap as well as high alumina clays such as kaolin.
- In accordance with the purposes and benefits set forth herein, a new and improved cement clinker composition defined by oxide content comprises: 42-65 wt % CaO; 5-20 wt % SiO2; 10-40 wt % Al2O3; 0.5-5 wt % Fe2O3; and 2-13 wt % SO3. More specifically, the new and improved clinker composition may comprise: 50-55 wt % CaO; 9-13 wt % SiO2; 20-30 wt % Al2O3; 0.5-3 wt % Fe2O3; and 5-10 wt % SO3.
- In accordance with yet another aspect, a new and improved cement clinker composition comprises between about 0.1 and 3.0 wt % fluoride compound and between about 0.5 and about 5.0 wt % Fe2O3. Such a composition may be fired at a temperature of between about 1150-1350° C. More preferably such a cement clinker composition is fired at temperature of between 1200-1300° C. After firing, such a composition provides between about 15 and 40 wt % alite and between about 20 and about 60 wt % calcium sulfoaluminate.
- In accordance with an additional aspect, the new and improved cement clinker composition comprises: 15-40 wt % C3S; 20-60 wt % C4A3Ś; 5-30 wt % C2S; 1-10 wt % C4AF; and 0.4-1.0 wt % CaF2 as present in fluorellestadite and fluormayenite clinker phases fired at 1150-1350° C. and more particularly 1200-1300° C. More specifically, the new and improved cement clinker composition comprises: 20-35 wt % C3S; 40-55 wt % C C4A3Ś; 10-25 wt % C2S; 1-4 wt % C4AF; and 0.6-0.8 wt % CaF2 as present in fluorellestadite and fluormayenite clinker phases fired at 1150-1350° and more particularly 1200-1300° C.
- In the following description, there are shown and described several preferred embodiments of the cement clinker composition. As it should be realized, the cement clinker composition is capable of other, different embodiments and its several details are capable of modification in various, obvious aspects all without departing from the composition as set forth and described in the following claims. Accordingly, the drawings and descriptions should be regarded as illustrative in nature and not as restrictive.
- The accompanying drawing figures incorporated herein and forming a part of the patent specification, illustrate several aspects of the cement clinker composition and together with the description serve to explain certain principles thereof.
-
FIG. 1 is graph of DSC/TGA (SDT) data illustrating the influence of fluorellestadite and ferrite within A/CSA clinkers. -
FIG. 2 is a bar graph of resistivity as a function of time for cement made with the new and improved clinker composition compared to commercial cements. -
FIG. 3 is a bar graph of compressive strength as a function of time for cement made with the new and improved clinker composition compared to commercial cements. -
FIG. 4 is a line graph of length change as a function of time for cement made with the new and improved clinker composition compared to commercial cements. - Cement Notation used throughout this document:
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Chemical Formula Cement Notation CaO C SiO2 S Al2O3 A Fe2O3 F SO3 Ś M MgO - The alternative binder presented in this novel cement clinker composition is alite-calcium sulfoaluminate (A-CSA) cement. A-CSA clinker combines alite (C3S) and calcium sulfoaluminate (CSA, ye'elimite or C4A3Ś) phases. These are the phases responsible for most of the strength development in OPC and CSA cements, respectively. Until recently, A-CSA clinker was not considered practical due to the perceived incompatible coexistence of both clinker phases. Alite forms at 1450-1500° C., while CSA decomposes at 1300-1350° C. [3-5] The introduction of mineralizers and fluxes, such as calcium fluoride and calcium sulfate [6-13], barium and strontium [14-16], or other elements such as titanium [17], partly resolved this issue, however improvements in this field were needed.
- This document demonstrates that the use of both calcium fluoride and iron oxide in the production of A/CSA clinker reduces the melting temperature and increases the formation of alite. Previously, it was found that the presence of sulfate hinder the formation of alite, but as this document demonstrates the production of increased levels of alite (30 wt. %) with high levels of calcium sulfoaluminate (50 wt. %) in the clinker. This binder formulation exhibits superior mechanical properties to both commercial OPC and CSA cement, including higher compressive strength, high resistivity, and high dimensional stability.
- The new and improved cement clinker composition as defined by oxide content incorporates about 42-65 wt % CaO; about 5-20 wt % SiO2; about 10-40 wt % Al2O3; about 0.5-5 wt % Fe2O3; and about 2-13 wt % SO3. In at least one particularly useful embodiment, the new and improved clinker composition incorporates about 50-55 wt % CaO; about 9-13 wt % SiO2; about 20-30 wt % Al2O3; about 0.5-3.0 wt % Fe2O3; and about 5-10 wt % SO3.
- In one or more embodiments, the cement clinker composition includes between about 0.1 and about 3.0 wt % fluoride compound and between about 0.5 and about 5.0 wt % Fe2O3. The fluoride compound may comprise, for example, calcium fluoride (CaF2), pickling liquor sludge containing fluoride and the like.
- In one or more embodiments, the cement clinker composition includes between about 10-35 wt % of a bauxite substitute selected from a group consisting of high fly ash alumina, aluminum dross, aluminum scrap, high alumina clays and combinations thereof. For purposes of this document, “high fly ash alumina” means a fly ash containing at least 20 wt. % of Al2O3, and more preferably at least 40 wt. % of Al2O3. For purposes of this document, “high alumina clays” means a clay containing at least 10 wt. % of Al2O3, and more preferably at least 20 wt. % of Al2O3, such as kaolin compound.
- In one or more embodiments, the cement clinker composition incorporates about 15-40 wt % C3S; about 20-60 wt % C4A3Ś; about 5-30 wt % C2S; about 1-10 wt % C4AF; and about 0.4-1.0 wt % CaF2 as present in fluorellestadite and fluormayenite clinker phases fired at about 1150-1350° C., 1200-1300° C. or 1225-1275° C. More specifically, the new and improved cement clinker composition incorporates about 20-35 wt % C3S; about 40-55 wt % C4A3Ś; about 10-25 wt % C2S; about 1-4 wt % C4AF; and about 0.6-0.8 wt % CaF2 as present in fluorellestadite and fluormayenite clinker phases fired at about 1150-1350° C. or 1200-1300° C. In one or more embodiments, the cement clinker composition is fired at about 1225-1275° C.
- In one or more embodiments, the cement clinker composition further includes between about 0.5-2.0 wt % Fe2O3. In one or more embodiments, that cement clinker composition also includes between about 10-35 wt % of a bauxite substitute selected from a group consisting of high fly ash alumina, aluminum dross, aluminum scrap, high alumina clays and combinations thereof.
- In one or more of the many possible embodiments, the new and improved cement clinker composition comprises between about 0.1 and 3.0 wt % of a fluoride compound, such as CaF2, pickling liquor sludge including fluoride or the like, and between about 0.5 and about 5.0 wt % Fe2O3. Such a composition may be fired at a temperature of between about 1150-1350° C. or 1200-1300° C. More preferably such a cement clinker composition is fired at temperature of between 1225-1275° C. Further, such a cement clinker composition may include between about 10-35 wt % of a bauxite substitute selected from a group consisting of high fly ash alumina, aluminum dross, aluminum scrap, high alumina clays and combinations thereof.
- A calculated clinker composition composed of 50 wt. % alite and 50 wt. % calcium sulfoaluminate was investigated. Four compositions were tested: #1 with no additions of CaF2 or iron oxide; #2 with addition of only CaF2; #3 with addition of only iron oxide; and #4 with additions of both CaF2 and iron oxide. The compositions were produced from reagent chemicals, as presented in Table 1. Fe2O3 was added at a percentage of 1.3 wt. % to obtain approximately 5 wt. % of ferrite (C4AF) in the final clinker composition. Regarding the addition of CaF2, the target was to produce approximately 10 wt. % of fluorellestadite, a liquid phase. The calculated clinker compositions are presented in Table 2.
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TABLE 1 Mixtures of chemicals used to produce A/ CSA # 1 to A/CSA # 4 in weight percentagesMixtures Reagent Chemicals A/CSA Comments Ca(OH)2 SiO2 Al(OH)3 Fe2O3 CaSO4 · 0.5H2O CaF2 #1 No fluorellestadite 51.54 9.86 29.6 — 9.0 — or ferrite # 2 Only 51.235 9.815 29.4 — 8.95 0.6 fluorellestadite # 3 Only ferrite 50.89 9.21 29.6 1.3 9.0 — #4 Both fluorellestadite 50.57 9.13 29.5 1.3 8.895 0.605 or ferrite -
TABLE 2 Calculated clinker compositions in wt. % for A/ CSA # 1 to A/CSA # 4Calculated Clinker Compositions (in wt.%) Mixtures C3S C2S C4A3Ś C4AF CŚ CaF2 A/ CSA # 148.5 — 49.9 — — — A/ CSA # 248.0 0.1 49.5 — — 0.78 A/ CSA # 345.0 0.1 47.7 5.0 0.5 — A/ CSA # 444.7 — 47.4 5.0 0.4 0.78 - A/
CSA # 1 to A/CSA # 4 were produced by mixing the raw materials with the quantities as described in Table 1 with an additional 10 wt. % of deionized water in a mortar and pestle until a homogenized powder was obtained. A part of the powder was kept for SDT analyses. A few 28×7 mm pellets were formed using a load of 25000 lbs, and dried overnight in an oven at 60° C. The pellets were then fired in a box furnace, and followed the firing program: 1—heat from room temperature to 800° C. at 7.5° C./min; 2—dwell at 800° C. for 30 min; 3—heat from 800° C. to 1250° C. at 5.0° C./min; 4—dwell at 1150/1200/1250° C. for 60 min; and 5—quench rapidly in air. The clinker pellets were then crushed in a shatter box until a fine powder was obtained. - Results:
- About the A/CSA Clinker
- Evidence about the Reduction of the Melting Temperature:
- The influence of additions of CaF2 (to form fluorellestadite) and iron oxide (to form ferrite) on A/CSA clinkers was studied through Simultaneous Different Scanning calorimetry and Thermogravimetry Analysis (SDT). The experiments were performed with a TA Instruments SDT Q600, under air atmosphere at a rate of 100 mL/min, from 50° C. to 1400° C., at a heating rate of 10° C./min. The results are presented in
FIG. 1 . - Below 600° C., all four A/CSA samples present the same SDT results, where three main peaks are present: at around 100° C. referring to the release of water; at around 300° C. referring to the decomposition of aluminium hydroxide; and at around 450° C. referring to the decomposition of calcium hydroxide. The weight losses for all three peaks are confirmed by the TGA results. The SDT curves of the four A/CSA clinkers differ above 600° C. Compositions A/CSA #1 (no fluorellestadite or ferrite formed) and A/CSA #3 (only ferrite formed) showed melting temperatures at 1259° C. and 1249° C., respectively. The formation of 5 wt. % of ferrite within A/
CSA # 3 clinker did not considerably decrease the melting temperature of A/CSA clinkers. On the other hand, A/CSA #2 (only fluorellestadite formed) and A/CSA #4 (fluorellestadite and ferrite formed) exhibited lower melting temperatures, at 1194° C. and 1187° C., respectively. Compared to the composition A/CSA # 1, the melting temperature decreased by 65° C. when fluorellestadite was formed, and by 72° C. when both fluorellestadite and ferrite were formed. Based on these SDT results, the influence of both fluorellestadite and ferrite within the formation of A/CSA clinkers increased the reduction of the melting temperature. - Evidence about the Formation of High Alite and High Calcium Sulfoaluminate Clinker:
- The influence of adding fluorellestadite and ferrite to the raw mix of A/CSA clinkers was determined by XRD/Rietveld analyses. The same compositions as presented in Table 1 and studied through SDT analyses were fired at different temperatures of 1150° C., 1200° C., and 1250° C. for 60 minutes. The results are presented below in Table 3.
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TABLE 3 Clinker compositions determined by Rietveld for A/ CSA # 1 to A/CSA # 4 fired at1150°, 1200°, and 1250° C. for 60 minutes. Rietveld parameters to ensure accuracy of the results are added: Rexp = Expected R Factor; Rp = Residual of Least-Squares Refinement; Rwp = Weighted Profile R-Factor; and GoF = Goodness of Fit. Clinker phases A/CSA #1 A/CSA #2 A/CSA #3 A/ CSA # 4Firing Temperature (° C.) 1150 1200 1250 1150 1200 1250 1150 1200 1250 1150 1200 1250 C3S 1.1 1.3 — — 1.3 21.4 — — 3.1 — 3.6 26.9 C2S 40.5 39.1 39.7 38.9 38.7 21.7 35.0 37.0 36.4 35.5 33.4 14.4 C4A3Ś 36.5 47.1 47.7 43 41.8 50.4 44.8 48.2 47.7 42.3 44.3 50.5 C4AF — 2.7 1.5 — 0.6 — 3.9 4.7 4.2 4 4.4 3.2 CŚ 2.9 — — — — 0.1 — — — — — 0.1 C 11.5 7.9 10.3 10.6 9 4.6 11.1 9 8.4 10 6.2 2.8 M 0.2 0.4 0.7 0.4 0.3 0.1 0.4 0.4 0.3 0.4 0.6 0.2 C12A7 5.2 — — — — — — — — — — — CA 2.2 — — — — — — — — — — — C3A — — — — — — — — — — — — C11A7CaF2 — 1.5 — 3.8 7.2 1.5 1.3 0.7 — 5.3 6.8 1.9 3C2S · 3CŚ · CaF2 — — — 3.3 1.1 — — — — 2.6 0.8 — Rexp 3.29 3.34 3.27 3.29 3.30 3.27 3.14 3.11 3.12 3.12 3.14 3.13 Rp 5.54 5.62 5.60 4.88 5.11 5.41 4.94 5.05 4.82 4.55 4.55 4.79 Rwp 8.06 8.19 8.25 7.07 7.38 7.96 7.15 7.48 7.13 6.54 6.58 6.94 GoF 6.00 6.02 6.35 4.63 5.01 5.94 5.20 5.76 5.24 4.39 4.39 4.92 - The composition A/
CSA # 1 without the formation of fluorellestadite or ferrite, did not form any measurable alite, at all three firing temperatures. Formation of belite was constant for all three firing temperatures, at around 40 wt. %. The formation of ye′ elimite increased with the firing temperature, especially between 1150° C. and 1200° C., from 36.5 to 47.1 wt. %. Instead of forming essentially ye'elimite at 1150° C., other clinker phases were present, such as mayenite (5.2 wt. %), calcium aluminate (2.2 wt. %) and anhydrite (2.9 wt. %). At 1200° C., mayenite, calcium aluminate, and anhydrite were no longer present, while more ye'elimite had been formed. The free lime content decreased with the increasing firing temperature, from 11.5, to 7.9, and 10.3 wt. %, at 1150, 1200, and 1250° C. - The composition A/CSA #2 (only CaF2 added) contained a significant amount of alite when fired at 1250° C., at 21.4 wt. %, and 4.6 wt. % of free lime. At lower firing temperatures, mostly belite and ye'elimite were present, with free lime, C11A7CaF2, and fluorellestadite. As studied previously in other works, the addition of calcium fluoride does provide benefit in reducing the firing temperature by forming a liquid phase, fluorellestadite, at a low temperature. Fluorellestadite does contribute to the formation of alite at a low firing temperature of 1250° C.
- The composition A/CSA #3 (only iron oxide added) contained a small amount of alite (3.1 wt. %), only at 1250° C. As expected, belite and ye'elimite are the major clinker phases present and ferrite is present at around 4.0-4.5 wt. % at all three firing temperatures. In addition, the free lime content does not seem to decrease significantly, even at high firing temperature of 1250° C., with a content of 8.4 wt. %. In OPC, the clinker ferrite is known to form a liquid phase promoting the formation of alite via a flux mechanism. Recent work by Lu et al. discusses the influence of ferrite on the formation and coexistence of ye'elimite and alite. They demonstrated that the addition of 20 wt. % of ferrite within an A/CSA clinker (from calculation: 15 wt. % C3S, 42 wt. % C2S, 23 wt. % C4A3Ś, and 20 wt. % C4AF) facilitated the coexistence of both phases at 1350° C. A/
CSA # 3 clinker confirms their results, that the addition of a small amount of ferrite, here 5 wt. %, does contribute to the formation of alite in small quantity. - The final composition, A/CSA #4 (CaF2 and iron oxide added), contained a significant amount of alite and ye'elimite, of 26.9 wt. % and 50.5 wt. % respectively, and a low amount of free lime, (2.8 wt. %), when fired at 1250° C. At low firing temperatures of 1150° C. and 1200° C., almost no alite was present, and only belite, ye'elimite and free lime. Even though this composition, when fired at 1250° C., still contains free lime at a level above our target of 2.0%, it proves that the addition of both fluorellestadite and ferrite in combination improves the clinkering process by decreasing the firing temperature needed to form A/CSA clinkers and forming a significant amount of alite and ye′ elimite.
- As mentioned earlier, other works have demonstrated the production of A/CSA clinkers, but with much lower quantities of alite. As a few examples, Londono-Zuluaga et al. produced a A/CSA clinker with 60 wt. % belite, 14 wt. % ye'elimite, and 10 wt. % alite, by adding 0.9 wt. % CaF2 to the raw mixture, and sintering at 1300° C. for 15 minutes. In another work by Ma et al., they demonstrated a two stage process for the production of a A/CSA clinker based on a OPC clinker, containing in the final clinker less than 4 wt. % ye'elimite, when fired at 1250° C.
- While first interpreting the SDT data, it did not seem that the formation of both fluorellestadite and ferrite together within A/CSA clinker effectively improved the reduction in the firing temperature, when compared with only the addition of fluorellestadite as only a 7° C. difference in temperature was observed between A/
CSA # 2 and A/CSA # 4. However, when interpreting the Rietveld data, the results unequivocally demonstrated that presence of both phases successfully enhanced the formation of alite, reduced the firing temperature, and free lime content. - Experiments were run again at 1250° C. and this time, the difference of adding only CaF2 and adding both CaF2 and iron oxide was obvious, as presented in Table 4.
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TABLE 4 Calculated clinker compositions in wt. % for A/ CSA # 1 to A/CSA # 4 by following the equations ofestablished by Dr. Zhou [23]. Clinker compositions of samples presented in Tables 1 and 2, characterized by Rietveld method. A-CSA A-CSA A-CSA A-CSA # 1 #2 #3 #4 Expected/Calculated C3S 48.5 48.0 45 44.7 Compositions C2S 0 0.1 0.1 0 C4A3Ś 49.9 49.5 47.7 47.4 C4AF 0 0 5.0 5.0 CŚ 0 0 0.5 0.4 Mineralizers/ Fl* & Fluxes present None Fl* Ferrite Ferrite Rietveld Compositions C3S 0.4 13.4 4.0 24.5 C2S 45.6 33.1 42.6 22.6 C4A3Ś 40.5 42.6 39.3 42.8 C4AF 0.9 0.6 4.6 3.7 CŚ 0.1 0.0 0.2 0.1 C 8.4 5.6 7.2 2.8 M 0.2 0.1 0.2 — C12A7 0.1 — 0.5 2.8 CA 1.9 — — — C11A7CaF2 1.8 — 1.4 0.5 Fl* — 4.5 — — (Fl* = fluorellestadite) - About the A/CSA Cement
- An A/CSA clinker was produced from 55.7 wt. % of agricultural lime, 12.3 wt. % of FGD gypsum, 31.38 wt. % of high alumina ash, and 0.62 wt. % of calcium fluoride. In terms of oxide contents within the raw mix, the composition is: 52.6 wt. % CaO, 11.5 wt. % SiO2, 25.3 wt. % Al2O3, 1.3 wt. % Fe2O3, and 7.5 wt. % SO3, and minor compounds. The raw materials used can be easily replaced with current raw materials, such as limestone, marl/clay, bauxite, aluminium dross, and pickling liquor sludge. Other raw materials can also be introduced, as long as the oxide content of the final clinker is similar to the composition described above. Similar A/CSA clinker compositions with various available raw materials are presented in Table 5. The raw materials were milled together and fired at 1250° C. for 60 minutes, and ground to a particle size d(50) of around 13-14 μm. The final clinker was analysed by XRD/Rietveld and contained: 29.6 wt. % alite (C3S), 9.4 wt. % belite (C2S), 1.5 wt. % ferrite (C4AF), 50.8 wt. % ye'elimite (C4A3Ś), 0.6 wt. % anhydrite (CŚ), and 0.3 wt. % free lime. The other clinker phases are minor phases.
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TABLE 5 Possible alternative raw materials for the production of A/CSA clinkers (not limiting in scope) Raw Exemplary Alternative Alternative Materials in wt. % Embodiment-A/ CSA # 1 #2 Agriculture Lime 55.7 — — FGD Gypsum 12.3 9 9 CaF2 0.62 — — High alumina Ash 31.38 — — Aluminum Dross — — 20 Limestone — 62 62 Bauxite — 21.5 — Pickle liquor sludge — 1.5 1.5 Marl/Clay — 6 7.5 - Mechanical properties of A/CSA cements were tested alongside two commercial cements, an OPC Type I from Cemex and a CSA cement from Buzzi. The composition of the A/CSA cements with gypsum (CSA-NM-20G) and anhydrite (CSA-NM-15.8A) are presented in Table 6.
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TABLE 6 Compositions of mortar samples in grams Materials OPC CSA CSA-NM-20G CSA-NM-15.8A OPC Type I (Cemex) 450 — — — CSA Cement (Buzzi) — 450 — — A/CSA clinker — — 360 378.9 FGD Gypsum — — 90 — Anhydrite — — — 71.1 Sodium Citrate — 4.5 4.5 4.5 European Sand (EN-196) 1350 1350 1350 1350 DI Water 225 225 225 225 - European standard EN 196 was followed to produce mortar samples for compressive strength, resistivity, and dimensional stability measurements. Following the production of mortar samples, the samples were stored in a 100% humidity chamber, demolded after 24 hours, and tested after 1, 7, 14, 21, 28, 56, and 91 day. At each test day, the samples were tested for resistivity with the Resipod from Proceq, for dimensional stability by measuring the length, and for compressive strength.
- Evidence about the high resistivity of A/CSA cement compared to commercial cements:
- The resistivity data (see
FIG. 2 ) demonstrate that the A/CSA cement exhibits much higher resistivity compared to OPC cement at all ages. Compared to CSA cement, A/CSA cement is lower initially but increases to a similar level at 91 days. Resistivity is relatable to the level of interconnected pores and in a measure of durability. - Evidence about the High Compressive Strength A/CSA Cement Compared to Commercial Cements:
- The compressive strength data (see
FIG. 3 ) demonstrate that after one day the new and improved A/CSA cement is 2-3 times stronger than OPC and 145% stronger than CSA with A/CSA with anhydrite. For the first 14 days, A/CSA with anhydrite is the strongest. - Evidence about the High Stability in High Humidity Curing Room of A/CSA Cement Compared to Commercial Cements:
- The mortar samples were stable compared to the commercial cements meeting all requirements, with expansion and/or shrinkage of less than 0.08%, as can be seen from
FIG. 4 . - The following methods are also provided.
- Bullet List of the Method Steps for the Production of Clinker:
- 1. Select the raw materials that satisfies the chemical composition described in the following claims, especially the amounts of iron oxide and calcium fluoride;
- 2. For our exemplary embodiment—A/CSA, mix 55.7 wt. % agricultural lime, 12.3 wt. % FGD gypsum, 31.38 wt. % of high alumina ash (includes sufficient iron oxide), and 0.62 wt. % calcium fluoride;
- 3. Produce pellets by mixing raw mix with 10 wt. % of deionized water in a mortar and pestle until complete homogenization is obtained and pressing the raw mix using a 25000 lbs load;
- 4. Dry the pellets in an oven at 60° C. overnight;
- 5. Fire the pellets in a box furnace following the firing procedure: 1—ramp from room temperature to 800° C. at 7.5 C/min; 2—dwell for 30 min at 800° C.; 3—ramp from 800° C. to 1250° C. at 5 C/min; 4—dwell at 1250° C. for 60 min; 5—rapid quenching of the pellets;
- 6. Grind the pellets in a shatter box or ball mill until a particle size d(50) of around 5-15 μm is obtained, and preferably around 8-12 μm.
- 7. Verify the clinker composition by XRD/Rietveld analyses.
- Bullet List of the Method Steps for the Production of Cement:
- 1. Mix the A/CSA clinker with 20 wt. % FGD gypsum or 15.8 wt. % anhydrite until complete homogenization is obtained;
- 2. Follow EN-196 for the production and testing of mortar samples.
- Each of the following terms written in singular grammatical form: “a”, “an”, and the“, as used herein, means “at least one”, or “one or more”. Use of the phrase One or more” herein does not alter this intended meaning of “a”, “an”, or “the”. Accordingly, the terms “a”, “an”, and “the”, as used herein, may also refer to, and encompass, a plurality of the stated entity or object, unless otherwise specifically defined or stated herein, or, unless the context clearly dictates otherwise. For example, the phrases: “a unit”, “a device”, “an assembly”, “a mechanism”, “a component, “an element”, and “a step or procedure”, as used herein, may also refer to, and encompass, a plurality of units, a plurality of devices, a plurality of assemblies, a plurality of mechanisms, a plurality of components, a plurality of elements, and, a plurality of steps or procedures, respectively.
- Each of the following terms: “includes”, “including”, “has”, “having”, “comprises”, and “comprising”, and, their linguistic/grammatical variants, derivatives, or/and conjugates, as used herein, means “including, but not limited to”, and is to be taken as specifying the stated component(s), feature(s), characteristic(s), parameter(s), integer(s), or step(s), and does not preclude addition of one or more additional component(s), feature(s), characteristic(s), parameter(s), integer(s), step(s), or groups thereof. Each of these terms is considered equivalent in meaning to the phrase “consisting essentially of”. Each of the phrases “consisting of” and “consists of, as used herein, means “including and limited to”. The phrase “consisting essentially of means that the stated entity or item (system, system unit, system sub-unit device, assembly, sub-assembly, mechanism, structure, component element or, peripheral equipment utility, accessory, or material, method or process, step or procedure, sub-step or sub-procedure), which is an entirety or part of an exemplary embodiment of the disclosed invention, or/and which is used for implementing an exemplary embodiment of the disclosed invention, may include at least one additional feature or characteristic” being a system unit system sub-unit device, assembly, sub-assembly, mechanism, structure, component or element or, peripheral equipment utility, accessory, or material, step or procedure, sub-step or sub-procedure), but only if each such additional feature or characteristic” does not materially alter the basic novel and inventive characteristics or special technical features, of the claimed item.
- The term “method”, as used herein, refers to steps, procedures, manners, means, or/and techniques, for accomplishing a given task including, but not limited to, those steps, procedures, manners, means, or/and techniques, either known to, or readily developed from known steps, procedures, manners, means, or/and techniques, by practitioners in the relevant field(s) of the disclosed invention.
- Terms of approximation, such as the terms about, substantially, approximately, etc., as used herein, refers to ±10% of the stated numerical value. Use of the terms parallel or perpendicular are meant to mean approximately meeting this condition, unless otherwise specified.
- It is to be fully understood that certain aspects, characteristics, and features, of the cement clinker composition and method of making the same, which are, for clarity, illustratively described and presented in the context or format of a plurality of separate embodiments, may also be illustratively described and presented in any suitable combination or sub-combination in the context or format of a single embodiment. Conversely, various aspects, characteristics, and features, of the cement clinker composition and method of making the same which are illustratively described and presented in combination or sub-combination in the context or format of a single embodiment may also be illustratively described and presented in the context or format of a plurality of separate embodiments.
- Although the cement clinker composition and method of making the same have been illustratively described and presented by way of specific exemplary embodiments, and examples thereof, it is evident that many alternatives, modifications, or/and variations, thereof, will be apparent to those skilled in the art. The cement clinker compositions described above and in the following claims may also be accurately expressed as “consisting of” rather than “comprising” the formulations indicated in the body of the following claims. Accordingly, it is intended that all such alternatives, modifications, or/and variations, fall within the spirit of, and are encompassed by, the broad scope of the appended claims.
- The foregoing has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the embodiments to the precise form disclosed. Obvious modifications and variations are possible in light of the above teachings. All such modifications and variations are within the scope of the appended claims when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled.
Claims (17)
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