WO2023202777A1 - Methods for processing cement comprising constructions or building materials - Google Patents
Methods for processing cement comprising constructions or building materials Download PDFInfo
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- WO2023202777A1 WO2023202777A1 PCT/EP2022/060577 EP2022060577W WO2023202777A1 WO 2023202777 A1 WO2023202777 A1 WO 2023202777A1 EP 2022060577 W EP2022060577 W EP 2022060577W WO 2023202777 A1 WO2023202777 A1 WO 2023202777A1
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- asbestos
- particle size
- building materials
- cement
- construction
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- 238000000034 method Methods 0.000 title claims abstract description 43
- 239000004568 cement Substances 0.000 title claims abstract description 35
- 239000004566 building material Substances 0.000 title claims abstract description 31
- 238000010276 construction Methods 0.000 title claims abstract description 31
- 239000002245 particle Substances 0.000 claims abstract description 55
- 239000000835 fiber Substances 0.000 claims abstract description 50
- 239000010425 asbestos Substances 0.000 claims abstract description 41
- 229910052895 riebeckite Inorganic materials 0.000 claims abstract description 41
- 239000002002 slurry Substances 0.000 claims abstract description 34
- 239000004035 construction material Substances 0.000 claims abstract description 30
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000011490 mineral wool Substances 0.000 claims abstract description 14
- 239000011491 glass wool Substances 0.000 claims abstract description 10
- 238000010438 heat treatment Methods 0.000 claims abstract description 8
- 230000006378 damage Effects 0.000 claims abstract description 7
- 229920003043 Cellulose fiber Polymers 0.000 claims abstract description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 22
- ULEFFCDROVNTRO-UHFFFAOYSA-N trimagnesium;disodium;dihydroxy(oxo)silane;iron(3+) Chemical compound [Na+].[Na+].[Mg+2].[Mg+2].[Mg+2].[Fe+3].[Fe+3].O[Si](O)=O.O[Si](O)=O.O[Si](O)=O.O[Si](O)=O.O[Si](O)=O.O[Si](O)=O.O[Si](O)=O.O[Si](O)=O ULEFFCDROVNTRO-UHFFFAOYSA-N 0.000 claims description 19
- CWBIFDGMOSWLRQ-UHFFFAOYSA-N trimagnesium;hydroxy(trioxido)silane;hydrate Chemical compound O.[Mg+2].[Mg+2].[Mg+2].O[Si]([O-])([O-])[O-].O[Si]([O-])([O-])[O-] CWBIFDGMOSWLRQ-UHFFFAOYSA-N 0.000 claims description 19
- 239000000463 material Substances 0.000 claims description 17
- 150000001875 compounds Chemical class 0.000 claims description 11
- 239000000377 silicon dioxide Substances 0.000 claims description 10
- 239000000843 powder Substances 0.000 claims description 7
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 6
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 claims description 6
- XYCWOLUUHSNDRX-UHFFFAOYSA-L [dioxido-[oxo(trioxidosilyloxy)silyl]oxysilyl]oxy-[[dioxido-[oxo(trioxidosilyloxy)silyl]oxysilyl]oxy-oxosilyl]oxy-dioxidosilane iron(2+) dihydroxide Chemical compound [OH-].[OH-].[Fe++].[Fe++].[Fe++].[Fe++].[Fe++].[Fe++].[Fe++].[O-][Si]([O-])([O-])O[Si](=O)O[Si]([O-])([O-])O[Si](=O)O[Si]([O-])([O-])O[Si]([O-])([O-])O[Si](=O)O[Si]([O-])([O-])[O-] XYCWOLUUHSNDRX-UHFFFAOYSA-L 0.000 claims description 5
- 229910052891 actinolite Inorganic materials 0.000 claims description 5
- 229910052885 anthophyllite Inorganic materials 0.000 claims description 5
- 231100001261 hazardous Toxicity 0.000 claims description 5
- 229910052751 metal Inorganic materials 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 5
- 239000011324 bead Substances 0.000 claims description 4
- NPUJHQNGUMWIMV-UHFFFAOYSA-L dicalcium pentamagnesium [dioxido-[oxo(trioxidosilyloxy)silyl]oxysilyl]oxy-[[dioxido-[oxo(trioxidosilyloxy)silyl]oxysilyl]oxy-oxosilyl]oxy-dioxidosilane dihydroxide Chemical compound [OH-].[OH-].[Mg++].[Mg++].[Mg++].[Mg++].[Mg++].[Ca++].[Ca++].[O-][Si]([O-])([O-])O[Si](=O)O[Si]([O-])([O-])O[Si](=O)O[Si]([O-])([O-])O[Si]([O-])([O-])O[Si](=O)O[Si]([O-])([O-])[O-] NPUJHQNGUMWIMV-UHFFFAOYSA-L 0.000 claims description 4
- 230000001376 precipitating effect Effects 0.000 claims description 4
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 3
- 239000001175 calcium sulphate Substances 0.000 claims description 3
- 235000011132 calcium sulphate Nutrition 0.000 claims description 3
- 229920000876 geopolymer Polymers 0.000 claims description 3
- 239000010440 gypsum Substances 0.000 claims description 3
- 229910052602 gypsum Inorganic materials 0.000 claims description 3
- 239000007791 liquid phase Substances 0.000 claims description 3
- 238000005191 phase separation Methods 0.000 claims description 3
- 238000004062 sedimentation Methods 0.000 claims description 3
- 239000007790 solid phase Substances 0.000 claims description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 2
- 239000005864 Sulphur Substances 0.000 claims description 2
- 239000003513 alkali Substances 0.000 claims description 2
- 229910052783 alkali metal Inorganic materials 0.000 claims description 2
- 150000001340 alkali metals Chemical class 0.000 claims description 2
- 150000001860 citric acid derivatives Chemical class 0.000 claims description 2
- 239000011521 glass Substances 0.000 claims description 2
- 239000002738 chelating agent Substances 0.000 claims 1
- 239000003365 glass fiber Substances 0.000 abstract description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 10
- 229910052620 chrysotile Inorganic materials 0.000 description 10
- 238000000724 energy-dispersive X-ray spectrum Methods 0.000 description 7
- 229910052500 inorganic mineral Inorganic materials 0.000 description 7
- 239000011707 mineral Substances 0.000 description 7
- 235000010755 mineral Nutrition 0.000 description 7
- 238000002354 inductively-coupled plasma atomic emission spectroscopy Methods 0.000 description 5
- 229910052742 iron Inorganic materials 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 238000004458 analytical method Methods 0.000 description 4
- 239000011575 calcium Substances 0.000 description 4
- 229910052791 calcium Inorganic materials 0.000 description 4
- 239000011777 magnesium Substances 0.000 description 4
- 239000011159 matrix material Substances 0.000 description 4
- 229910052710 silicon Inorganic materials 0.000 description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 3
- 229910052749 magnesium Inorganic materials 0.000 description 3
- 238000001878 scanning electron micrograph Methods 0.000 description 3
- 238000005549 size reduction Methods 0.000 description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- 238000004626 scanning electron microscopy Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 206010061218 Inflammation Diseases 0.000 description 1
- 208000019693 Lung disease Diseases 0.000 description 1
- 206010058467 Lung neoplasm malignant Diseases 0.000 description 1
- 206010027406 Mesothelioma Diseases 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 239000004115 Sodium Silicate Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 229910052612 amphibole Inorganic materials 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical class [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000004567 concrete Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000004992 fission Effects 0.000 description 1
- 229910052888 grunerite Inorganic materials 0.000 description 1
- 239000011874 heated mixture Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000004054 inflammatory process Effects 0.000 description 1
- 235000014413 iron hydroxide Nutrition 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 210000004072 lung Anatomy 0.000 description 1
- 201000005202 lung cancer Diseases 0.000 description 1
- 208000020816 lung neoplasm Diseases 0.000 description 1
- 210000002540 macrophage Anatomy 0.000 description 1
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical class [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 1
- 235000012254 magnesium hydroxide Nutrition 0.000 description 1
- HCWCAKKEBCNQJP-UHFFFAOYSA-N magnesium orthosilicate Chemical compound [Mg+2].[Mg+2].[O-][Si]([O-])([O-])[O-] HCWCAKKEBCNQJP-UHFFFAOYSA-N 0.000 description 1
- 239000000391 magnesium silicate Substances 0.000 description 1
- 229910052919 magnesium silicate Inorganic materials 0.000 description 1
- 235000019792 magnesium silicate Nutrition 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000012783 reinforcing fiber Substances 0.000 description 1
- 210000002345 respiratory system Anatomy 0.000 description 1
- 229910052616 serpentine group Inorganic materials 0.000 description 1
- 229910052604 silicate mineral Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 229910052911 sodium silicate Inorganic materials 0.000 description 1
- 229910052889 tremolite Inorganic materials 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
- B09B3/30—Destroying solid waste or transforming solid waste into something useful or harmless involving mechanical treatment
- B09B3/35—Shredding, crushing or cutting
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
- B09B3/40—Destroying solid waste or transforming solid waste into something useful or harmless involving thermal treatment, e.g. evaporation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE
- B09B2101/00—Type of solid waste
- B09B2101/35—Asbestos
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE
- B09B2101/00—Type of solid waste
- B09B2101/40—Asphalt
Definitions
- the present invention relates to methods for processing cement comprising construction or building materials such as panels, pipes, corrugated roofing sheets, flat sheets, roofing tiles and water tubes and especially to methods for processing cement comprising construction or building materials in combination with, or containing fibers, cellulose fibers asbestos fibers, glass wool, glass fibers, rockwool or rockwool fibers whereby the processing results in complete destructions of both bound and unbound fibers.
- Cement is a substance used for construction that sets, hardens, and adheres to other materials to bind them together.
- Cement can be used in combinations such as in combination with sand or gravel.
- Cement mixed with fine aggregate is used to produce mortar, or with sand and gravel, to produce concrete.
- Asbestos cement also designated as eternit, fibro or fibrolite, is a building material in which asbestos fibers are used to reinforce rigid construction or building materials such as cement sheets, panels or pipes.
- asbestos is generally used to designate a group of six naturally occurring fibrous silicate minerals.
- Five of the asbestos minerals (crocidolite, amosite, tremolite, actinolite, anthophyllite) belong to the amphibole group of minerals, one asbestos mineral (chrysotile) belongs to the serpentine group of minerals.
- Chrysotile, crocidolite and amosite are the most widespread applied types of asbestos and are often referred to as white, blue and brown asbestos, respectively.
- the color of the asbestos is related to its chemical composition with chrysotile being predominantly a magnesium silicate (Mg3Si2Os(OH)4), crocidolite predominantly being an iron, magnesium, sodium silicate (Na2((Fe 2+ , Mg 2+ )3Fe 3+ 2)Si 8 O22(OH)2 and amosite being an iron silicate (Fe 7 Si 8 O22(OH)2).
- chrysotile being predominantly a magnesium silicate (Mg3Si2Os(OH)4)
- crocidolite predominantly being an iron, magnesium, sodium silicate (Na2((Fe 2+ , Mg 2+ )3Fe 3+ 2)Si 8 O22(OH)2
- amosite being an iron silicate (Fe 7 Si 8 O22(OH)2).
- asbestos finer bundles can release microscopic small fibers of less than 0.5pm thickness. When inhaled, these fibrils are dangerous, and inhalation of asbestos is related to severe lung diseases like mesothelioma and lung cancer.
- Crocidolite and amosite are considered to be more hazardous than chrysotile. Fibers longer than 100 pm are considered non-respirable as they are mostly filtered out in the upper respiratory tract. Smaller fibers are able to penetrate the lung tissue and cause local inflammation. Fibers smaller than approximately 5 pm are encapsulated by macrophages and effectively shielded from surrounding tissue without causing further damage. It is therefore the 5 pm to 100 pm fiber fraction range that is of most concern. Additionally, the ratio between the length and thickness is of importance.
- asbestos cement Upon weathering, asbestos cement will release their fiber content in the environment and pose a long-term hazard. It is therefore imperative to dispose of these asbestos containing materials in an effective, affordable, and sustainable way. However, the larger part of these products consists of cement minerals which in themselves are harmless and don’t need to be treated with similar precautions as the asbestos minerals.
- asbestos cement other reinforcing fibers such as glass, mineral and cellulose fibers are used in combination with cement as construction or building materials.
- Rock wool, glass wool and mineral wool are also commonly used in construction and building materials.
- all these materials suffer to a certain extent from similar hazardous properties as asbestos.
- this object of the present invention is met by methods for processing cement comprising construction or building materials, the methods comprise the steps of: a) suspending cement comprising construction or building materials with a particle size of less than 1.5 mm in water wherein the mass ratio cement comprising construction or building materials to water is from 1:1 to 1:50 and subsequently mechanically reducing the particle size of the slurry to less than 100 pm; b) heating the slurry obtained in step (a) to a temperature between 60°C to 99°C and, simultaneously, or sequentially, mechanically reducing the particle size of the slurry to less than 10 pm.
- the present inventors have surprisingly discovered that the above methods suffice to convert, or recycle, cement comprising construction or building materials.
- the slurry obtained after step (b) can be further processed into calcium carbonate (chalk) and/or calcium sulphate (gypsum) from the liquid phase obtained after step (b) and silica comprising material from the semi solid phase obtained after step (b) can be processed into geopolymers.
- a liquid phase and a semi-solid phase can be readily obtained by phase separation, or sedimentation, of the slurry of step (b). It is noted that according to the present invention, no pH increasing agent such as KOH and NaOH are required to be added in steps (a) and (b).
- the present methods are especially suitable to process, or recycle, construction or building materials comprising, or in combination with, fibers, cellulose fibers, silica containing fibers such as asbestos, glass wool, glass, or rock wool since the process allows complete destruction of these fibers.
- fiber denotes particles with a length/thickness ratio of higher than 3.
- the term destruction of hazardous silica containing fiber denotes reducing the fiber length of the silica containing fiber to less than 10 pm, preferably 5 pm, for substantially all fibers such as more than 95%, such as more than 96%, 97%, 98%, 99% or 100% of the fibers.
- less than 5 pm also encompasses the absence of fibers or elongated particles.
- fiber length and “particle size” are used interchangeably to designate the longest dimension of an (elongated) particle or fiber.
- a particle size of less than 100 pm can similarly be used to designate a fiber with a length of less than 100 pm.
- the present methods are especially suitable for processing cementitious asbestos, glass wool or rock wool, preferably asbestos, comprising materials generally used as construction materials, panels, pipes, corrugated roofing sheets, flat sheets, roofing tiles and water tubes.
- the present methods are used to process, or recycle, construction or building materials comprising fibers of chrysotile asbestos, crocidolite asbestos, amosite asbestos, tremolite asbestos, actinolite asbestos, or anthophyllite asbestos.
- (a) results in particles with an average size distribution D95 between 10 pm to 80 pm, preferably a D95 of 20 pm to 50 pm.
- Dxx denotes that the portion of particles with a length smaller than this value is xx%, for example D95 denotes that the portion of particles with a length below this value is 95%.
- the length of the present particles relates to the longest dimension of the particles.
- step (b) results in particles with an average size distribution D95 between 0.5 pm to 5 pm, preferably a D95 of 1 pm to 3 pm, more preferably a D95 of 1 pm to 2 pm.
- Dxx denotes that the portion of particles with a length smaller than this value is xx%, for example D95 denotes that the portion of particles with a length below this value is 95%.
- the length of the present particles relates to the longest dimension of the particles.
- step (b) can, but not necessary, further comprise the addition of one or more compounds selected from the group consisting of pH modulating compounds, metal precipitating or binding compounds and carbonate bound alkali or earth alkali metals. Generally, these compounds are added to remove impurities or other unwanted compounds in the final product or to optimize the present methods.
- metal precipitating or binding compounds such as sulphur, citrates or chelates can be used to remove (heavy) metals from the slurry or final product.
- the slurry can be subjected to phase separation, or sedimentation, and/or further processing yielding, for example, calcium carbonate (chalk) and/or calcium sulphate (gypsum) and silica bound material which, for example, can be used for geopolymers.
- phase separation for example, calcium carbonate (chalk) and/or calcium sulphate (gypsum) and silica bound material which, for example, can be used for geopolymers.
- Present step (a) preferably comprises mechanically reducing the particle size or length of the slurry to less than 100 pm and is performed in, for example, a ball mill for 0.5 to 30 hours, preferably 2 to 30 hours and/or present step (b) preferably comprises mechanically reducing the particle size or length of the slurry to less than 10 pm and is performed, for example, in a bead mill for 0.5 to 10 hours such as 2 to 10 hours.
- the present methods comprise the steps of: al) mechanically reducing cement comprising construction or building materials to pieces of 5 to 20 cm; a2) mechanically reducing the pieces of step (al) to a powder with a particle size of less than 1.5 mm; a3) suspending the powder of step (a2) in water, wherein the mass ratio cement comprising construction or building materials to water is from 1 : 1 to 1:50; a4) mechanically reducing the particle size of the slurry of step (a3) to less than 100 pm; bl) heating the slurry obtained in step (a4) to a temperature between 60°C to 99°C during 1 to 5 hours; b2) mechanically reducing the particle size of the slurry of step (bl) to less than 10 pm.
- the present methods as detailed above are especially suitable for destruction of hazardous silica containing fibers selected from the group consisting of asbestos, glass wool, rock wool, chrysotile asbestos, crocidolite asbestos, amosite asbestos, tremolite asbestos, actinolite asbestos, and anthophyllite asbestos, preferably chrysotile asbestos and/or crocidolite asbestos.
- hazardous silica containing fibers selected from the group consisting of asbestos, glass wool, rock wool, chrysotile asbestos, crocidolite asbestos, amosite asbestos, tremolite asbestos, actinolite asbestos, and anthophyllite asbestos, preferably chrysotile asbestos and/or crocidolite asbestos.
- Figure 1 shows an SEM (Scanning Electron Microscopy) image of asbestos fibers in a cement matrix. Top image is chrysotile asbestos and bottom image is crocidolite asbestos;
- Figure 2 shows particle size or length distribution after present step (a);
- Figure 3 shows an SEM image of fibers after present step (a). Top image is chrysotile asbestos (magnification 3700x) and bottom image is crocidolite asbestos (magnification 3000x);
- Figure 4 shows particle size or length distribution after heating in present step (b);
- Figure 5 shows an SEM image after heating in present step (b). Top image is chrysotile asbestos (magnification 3500x) and bottom image is crocidolite asbestos (1900x);
- Figure 6 shows particle size or length distribution after present step (b);
- Figure 7 shows SEM images after present step (b). Top image after 60 minutes mechanical size reduction (magnification 3300x); middle image after 180 minutes mechanical size reduction (magnification 3000x); and bottom image after 300 minutes mechanical size reduction (magnification lOOOx).
- AC Asbestos cement roofing sheets
- the AC used was analyzed using Scanning Electron Microscope - Energy Dispersive X-ray spectroscopy (SEM-EDX) - on asbestos fibers (EDX spectrum not shown). Both chrysotile and crocidolite were found (10-15% chrysotile, 2-5% crocidolite, bounded, Figure 1). In Chrysotile, the woolly curved morphology was visible, in crocidolite straight crystals with a lot of fission. In the EDX spectrum (not shown) of chrysotile it was observed that the Mg peak was similar in size to the Si peak which is typical for chrysotile. In the EDX spectrum of crocidolite (not shown), an Fe peak and Na peak (at 1.0 keV) were observed.
- Step (a) Powder material from the pen mill (33 kg) was collected in a reactor vessel and mixed with water (88 kg) and thereafter the mixture was homogenized.
- the slurry obtained had a pH of 12.21. Subsequently, the slurry was pumped to a ball mill (300L, 30 rpm, 40% filled with aluminum oxide balls) and ground for 20 hours.
- Table 1 pH and dry residue before and after step (a).
- Table 2 average particle size (length) distribution after step (a) To determine whether material is dissolved, a sample of the slurry was filtered (0.45 pm filter) and analyzed with ICP (Inductively Coupled Plasma atomic emission spectroscopy). Only calcium was found in significant amounts (0.21%). With the ICP method, no silicon can be determined, although this is an important component of the matrix. Furthermore, it is striking that there was no iron and magnesium in solution, while this is amply present in the matrix and in the asbestos fibers. This can be due to the relatively high pH of the slurry causing iron and magnesium hydroxides to be insoluble.
- ICP Inductively Coupled Plasma atomic emission spectroscopy
- step (a) The slurry from step (a) was pumped into a reactor. After adding additional water (68 kg), the mixture was homogenized. The mixture was then heated and stirred for 2 hours at - 90°C and cooled overnight to 53 °C.
- Table 3 pH and dry residue before and after step (a).
- Table 4 average particle size (length) distribution after heating in step (b)
- the slurry was ground in a bead mill for 5 hours. Samples were taken during grinding and analyzed to assess asbestos degradation.
- EDX analysis of a point in the amorphous matrix was performed (EDX spectrum not shown). This is the same for the samples of 180, 240 and 300 minutes.
- the elements can be found from both the cement (Si, Ca, Al) and the elements that make up chrysotile (Si, Mg) and crocidolite (Si, Fe).
- the material obtained is a thick beige-gray slurry. The density is 1,08 g/L.
- Asbestos-containing roofing sheets were successfully reduced and treated into an asbestos-free material. This was done by breaking the roofing sheets and grinding the powder obtained in water. Then, the slurry was heated to 90°C and ground again resulting in complete breakdown of asbestos fibers.
Abstract
The present invention relates to methods for processing cement comprising construction or building materials such as panels, pipes, corrugated roofing sheets, flat sheets, roofing tiles and water tubes and especially to methods for processing cement comprising construction or building materials in combination with, or containing fibers, cellulose fibers asbestos fibers, glass wool, glass fibers, rockwool or rockwool fibers whereby the processing results in complete destructions of both bound and unbound fibers. Specifically, the present invention relates to methods for processing cement comprising construction or building materials, the methods comprise the steps of: a) suspending cement comprising construction or building materials with a particle size of less than 1.5 mm in water wherein the mass ratio cement comprising construction or building materials to water is from 1:1 to 1:50 and subsequently mechanically reducing the particle size of the slurry to less than 100 µm; b) heating the slurry obtained in step (a) to a temperature between 60°C to 99°C and, simultaneously, or sequentially, mechanically reducing the particle size of the slurry to less than 10 µm.
Description
METHODS FOR PROCESSING CEMENT COMPRISING CONSTRUCTION OR BUILDING MATERIALS
Description
The present invention relates to methods for processing cement comprising construction or building materials such as panels, pipes, corrugated roofing sheets, flat sheets, roofing tiles and water tubes and especially to methods for processing cement comprising construction or building materials in combination with, or containing fibers, cellulose fibers asbestos fibers, glass wool, glass fibers, rockwool or rockwool fibers whereby the processing results in complete destructions of both bound and unbound fibers.
Cement is a substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement can be used in combinations such as in combination with sand or gravel. Cement mixed with fine aggregate is used to produce mortar, or with sand and gravel, to produce concrete. Asbestos cement, also designated as eternit, fibro or fibrolite, is a building material in which asbestos fibers are used to reinforce rigid construction or building materials such as cement sheets, panels or pipes.
The term asbestos is generally used to designate a group of six naturally occurring fibrous silicate minerals. Five of the asbestos minerals (crocidolite, amosite, tremolite, actinolite, anthophyllite) belong to the amphibole group of minerals, one asbestos mineral (chrysotile) belongs to the serpentine group of minerals. Chrysotile, crocidolite and amosite are the most widespread applied types of asbestos and are often referred to as white, blue and brown asbestos, respectively. The color of the asbestos is related to its chemical composition with chrysotile being predominantly a magnesium silicate (Mg3Si2Os(OH)4), crocidolite predominantly being an iron, magnesium, sodium silicate (Na2((Fe2+, Mg2+)3Fe3+2)Si8O22(OH)2 and amosite being an iron silicate (Fe7Si8O22(OH)2).
When broken or mechanically bruised, asbestos finer bundles can release microscopic small fibers of less than 0.5pm thickness. When inhaled, these fibrils are dangerous, and inhalation of asbestos is related to severe lung diseases like mesothelioma and lung cancer.
Crocidolite and amosite are considered to be more hazardous than chrysotile. Fibers longer than 100 pm are considered non-respirable as they are mostly filtered out in the upper respiratory tract. Smaller fibers are able to penetrate the lung tissue and cause local inflammation. Fibers smaller than approximately 5 pm are encapsulated by macrophages and effectively shielded from surrounding tissue without causing further damage. It is therefore the 5 pm to 100 pm fiber fraction range that is of most concern. Additionally, the ratio between the length and thickness is of importance.
Upon weathering, asbestos cement will release their fiber content in the environment and pose a long-term hazard. It is therefore imperative to dispose of these asbestos containing materials in an effective, affordable, and sustainable way. However, the larger part of these products consists of cement minerals which in themselves are harmless and don’t need to be treated with similar precautions as the asbestos minerals.
As alternatives for asbestos cement, other reinforcing fibers such as glass, mineral and cellulose fibers are used in combination with cement as construction or building materials. Rock wool, glass wool and mineral wool are also commonly used in construction and building materials. However, all these materials suffer to a certain extent from similar hazardous properties as asbestos.
Accordingly, there is a need in the art for new processes for effectively processing construction or building materials and especially fibers such as asbestos, glass fiber, rock wool, glass wool and/or mineral wool comprising materials or, formulated differently, there is a need in the art for processes to recycle fiber comprising construction or building materials.
It is an object of the present invention, amongst other objects, to meet the above need in the art.
This object of the present invention, amongst objects, is met by providing methods as outlined in the appended claims.
Specifically, this object of the present invention, amongst other objects, is met by methods for processing cement comprising construction or building materials, the methods comprise the steps of: a) suspending cement comprising construction or building materials with a particle size of less than 1.5 mm in water wherein the mass ratio cement comprising construction or building materials to water is from 1:1 to 1:50 and subsequently mechanically reducing the particle size of the slurry to less than 100 pm; b) heating the slurry obtained in step (a) to a temperature between 60°C to 99°C and, simultaneously, or sequentially, mechanically reducing the particle size of the slurry to less than 10 pm.
The present inventors have surprisingly discovered that the above methods suffice to convert, or recycle, cement comprising construction or building materials. For example, the slurry obtained after step (b) can be further processed into calcium carbonate (chalk) and/or calcium sulphate (gypsum) from the liquid phase obtained after step (b) and silica comprising material from the semi solid phase obtained after step (b) can be processed into geopolymers. A liquid phase and a semi-solid phase can be readily obtained by phase separation, or sedimentation, of the slurry of step (b).
It is noted that according to the present invention, no pH increasing agent such as KOH and NaOH are required to be added in steps (a) and (b).
The present methods are especially suitable to process, or recycle, construction or building materials comprising, or in combination with, fibers, cellulose fibers, silica containing fibers such as asbestos, glass wool, glass, or rock wool since the process allows complete destruction of these fibers.
The term “fiber” according to the present invention denotes particles with a length/thickness ratio of higher than 3.
Within the context of the present invention, the term destruction of hazardous silica containing fiber denotes reducing the fiber length of the silica containing fiber to less than 10 pm, preferably 5 pm, for substantially all fibers such as more than 95%, such as more than 96%, 97%, 98%, 99% or 100% of the fibers. Within the context of the present invention, less than 5 pm also encompasses the absence of fibers or elongated particles.
Within the context of the present invention, the terms “fiber length” and “particle size” are used interchangeably to designate the longest dimension of an (elongated) particle or fiber. Thus, a particle size of less than 100 pm can similarly be used to designate a fiber with a length of less than 100 pm.
The present methods are especially suitable for processing cementitious asbestos, glass wool or rock wool, preferably asbestos, comprising materials generally used as construction materials, panels, pipes, corrugated roofing sheets, flat sheets, roofing tiles and water tubes.
According to an especially preferred embodiment, the present methods are used to process, or recycle, construction or building materials comprising fibers of chrysotile asbestos, crocidolite asbestos, amosite asbestos, tremolite asbestos, actinolite asbestos, or anthophyllite asbestos.
According to the present invention, mechanically reducing the particle size in step
(a) results in particles with an average size distribution D95 between 10 pm to 80 pm, preferably a D95 of 20 pm to 50 pm. Dxx denotes that the portion of particles with a length smaller than this value is xx%, for example D95 denotes that the portion of particles with a length below this value is 95%. As noted, the length of the present particles relates to the longest dimension of the particles.
According to the present invention, mechanically reducing the particle size in step
(b) results in particles with an average size distribution D95 between 0.5 pm to 5 pm, preferably a D95 of 1 pm to 3 pm, more preferably a D95 of 1 pm to 2 pm. Again, Dxx denotes that the portion of particles with a length smaller than this value is xx%, for example D95 denotes that the portion of particles with a length below this value is 95%. As noted, the length of the present particles relates to the longest dimension of the particles.
In the present processing or recycling methods, step (b) can, but not necessary, further comprise the addition of one or more compounds selected from the group consisting of pH modulating compounds, metal precipitating or binding compounds and carbonate bound alkali or earth alkali metals. Generally, these compounds are added to remove impurities or other unwanted compounds in the final product or to optimize the present methods.
For example, metal precipitating or binding compounds such as sulphur, citrates or chelates can be used to remove (heavy) metals from the slurry or final product.
According to the present invention, after step (b), the slurry can be subjected to phase separation, or sedimentation, and/or further processing yielding, for example, calcium carbonate (chalk) and/or calcium sulphate (gypsum) and silica bound material which, for example, can be used for geopolymers.
Present step (a) preferably comprises mechanically reducing the particle size or length of the slurry to less than 100 pm and is performed in, for example, a ball mill for 0.5 to 30 hours, preferably 2 to 30 hours and/or present step (b) preferably comprises mechanically reducing the particle size or length of the slurry to less than 10 pm and is performed, for example, in a bead mill for 0.5 to 10 hours such as 2 to 10 hours.
According to an especially preferred embodiment, the present methods comprise the steps of: al) mechanically reducing cement comprising construction or building materials to pieces of 5 to 20 cm; a2) mechanically reducing the pieces of step (al) to a powder with a particle size of less than 1.5 mm; a3) suspending the powder of step (a2) in water, wherein the mass ratio cement comprising construction or building materials to water is from 1 : 1 to 1:50; a4) mechanically reducing the particle size of the slurry of step (a3) to less than 100 pm; bl) heating the slurry obtained in step (a4) to a temperature between 60°C to 99°C during 1 to 5 hours; b2) mechanically reducing the particle size of the slurry of step (bl) to less than 10 pm.
The present methods as detailed above are especially suitable for destruction of hazardous silica containing fibers selected from the group consisting of asbestos, glass wool, rock wool, chrysotile asbestos, crocidolite asbestos, amosite asbestos, tremolite asbestos, actinolite asbestos, and anthophyllite asbestos, preferably chrysotile asbestos and/or crocidolite asbestos.
The present invention will be further detailed in an example. In the example, reference is made to the appended figures wherein:
Figure 1: shows an SEM (Scanning Electron Microscopy) image of asbestos fibers in a cement matrix. Top image is chrysotile asbestos and bottom image is crocidolite asbestos;
Figure 2: shows particle size or length distribution after present step (a);
Figure 3: shows an SEM image of fibers after present step (a). Top image is chrysotile asbestos (magnification 3700x) and bottom image is crocidolite asbestos (magnification 3000x);
Figure 4: shows particle size or length distribution after heating in present step (b);
Figure 5: shows an SEM image after heating in present step (b). Top image is chrysotile asbestos (magnification 3500x) and bottom image is crocidolite asbestos (1900x);
Figure 6: shows particle size or length distribution after present step (b);
Figure 7: shows SEM images after present step (b). Top image after 60 minutes mechanical size reduction (magnification 3300x); middle image after 180 minutes mechanical size reduction (magnification 3000x); and bottom image after 300 minutes mechanical size reduction (magnification lOOOx).
Example
Method and Results
Pretreatment
Asbestos cement roofing sheets (AC) were mechanically broken into pieces of about 10 cm. These pieces were further broken in a shredder and the broken material was ground into a powder in a pen mill.
The AC used was analyzed using Scanning Electron Microscope - Energy Dispersive X-ray spectroscopy (SEM-EDX) - on asbestos fibers (EDX spectrum not shown). Both chrysotile and crocidolite were found (10-15% chrysotile, 2-5% crocidolite, bounded, Figure 1). In Chrysotile, the woolly curved morphology was visible, in crocidolite straight crystals with a lot of fission. In the EDX spectrum (not shown) of chrysotile it was observed that the Mg peak was similar in size to the Si peak which is typical for chrysotile. In the EDX spectrum of crocidolite (not shown), an Fe peak and Na peak (at 1.0 keV) were observed.
Step (a)
Powder material from the pen mill (33 kg) was collected in a reactor vessel and mixed with water (88 kg) and thereafter the mixture was homogenized. The slurry obtained had a pH of 12.21. Subsequently, the slurry was pumped to a ball mill (300L, 30 rpm, 40% filled with aluminum oxide balls) and ground for 20 hours.
After grinding, the particle size was measured (laser diffraction). The particle size distribution observed is shown in Figure 2 and Table2. Almost all material is smaller than 100 pm. 90% of the material was smaller than 25 pm.
The pH and dry residues were determined before and after grinding (Table 1). The pH had increased to 12.6. This is slightly higher than the expected pH of 12.3 of a saturated calcium hydroxide solution. The dry residue was slightly decreased which was probably because some water had been added to pump the slurry.
To analyze the mixture after step (a), an SEM-EDX measurement (EDX spectrum not shown) and particle analysis were performed and numerous fibers were observed in the material (Figure 2 and Figure 3 and Table 2 below).
Table 2: average particle size (length) distribution after step (a)
To determine whether material is dissolved, a sample of the slurry was filtered (0.45 pm filter) and analyzed with ICP (Inductively Coupled Plasma atomic emission spectroscopy). Only calcium was found in significant amounts (0.21%). With the ICP method, no silicon can be determined, although this is an important component of the matrix. Furthermore, it is striking that there was no iron and magnesium in solution, while this is amply present in the matrix and in the asbestos fibers. This can be due to the relatively high pH of the slurry causing iron and magnesium hydroxides to be insoluble.
Step (b)
The slurry from step (a) was pumped into a reactor. After adding additional water (68 kg), the mixture was homogenized. The mixture was then heated and stirred for 2 hours at - 90°C and cooled overnight to 53 °C.
The particle size distribution after the reaction step was determined (Table 4, Figure 4) and the particle size was decreased as compared to step (a).
The pH and dry residue were also determined (Table 3) and the pH remained stable around 12.5. To determine whether material is dissolved, a sample of the slurry was filtered (0.45 pm filter) and analyzed with ICP. Only calcium was found in significant amounts (0.26 - 0.27%).
To characterize the heated mixture, an SEM-EDX (EDX spectrum not shown) measurement and particle analysis were performed (Figure 5). Fibers can still be observed. However, bundles appear to be split into more loose fibers.
Subsequently, the slurry was ground in a bead mill for 5 hours. Samples were taken during grinding and analyzed to assess asbestos degradation.
The particle size (Table 5 and Table 6 and Figure 6) decreased sharply during the first 60 minutes. From 180 minutes, no significant change in particle size can be seen. The pH remained constant at 12.6 during grinding, the dry matter content was also stable (Table 5). Table 5: particle size and other observations during grinding a bead mill
Table 6: average particle size (length) distribution after step (b)
The samples were viewed with a light microscope (lOOOx magnification). In the first sample, many fibers were visible. After 120 minutes of grinding, it became difficult to see any fibers. In the 240- and 300-minute samples, no fibers were visible.
The solutes were analyzed with ICP. Only calcium was found in significant amounts (0.25 - 0.28%).
In the analysis with SEM-EDX (EDX spectrum not shown) after 0, 30, 60 minutes, it was observed that the fibers became smaller and fractured. An example of crocidolite can be seen in Figure 7 (see also Table 5). In the analysis after 120 minutes, structures can be seen that look like fibers, but these could no longer be characterized as asbestos. After 180, 240 and 300 minutes of grinding, no asbestos fiber can be observed.
An EDX analysis of a point in the amorphous matrix was performed (EDX spectrum not shown). This is the same for the samples of 180, 240 and 300 minutes. In this EDX analysis, the elements can be found from both the cement (Si, Ca, Al) and the elements that make up chrysotile (Si, Mg) and crocidolite (Si, Fe). The material obtained is a thick beige-gray slurry. The density is 1,08 g/L.
Conclusion
Asbestos-containing roofing sheets were successfully reduced and treated into an asbestos-free material. This was done by breaking the roofing sheets and grinding the powder obtained in water. Then, the slurry was heated to 90°C and ground again resulting in complete breakdown of asbestos fibers.
Claims
1. Method for processing cement comprising construction or building materials, the method comprises the steps of: a) suspending cement comprising construction or building materials with a particle size of less than 1.5 mm in water wherein the mass ratio cement comprising construction or building materials to water is from 1:1 to 1:50 and subsequently mechanically reducing the particle size of the slurry to less than 100 pm; b) heating the slurry obtained in step (a) to a temperature between 60°C to 99°C and, simultaneously, or sequentially, mechanically reducing the particle size of the slurry to less than 10 pm.
2. Method according to claim 1, wherein cement comprising construction or building materials further comprise, or are in combination with, fibers, cellulose fibers and/or silica containing fibers.
3. Method according to claim 2, wherein the silica containing fibers are selected from the group consisting of asbestos, glass, glass wool, mineral wool and rock wool.
4. Method according to claim 3, wherein the asbestos is selected from the group consisting of chrysotile asbestos, crocidolite asbestos, amosite asbestos, tremolite asbestos, actinolite asbestos, and anthophyllite asbestos.
5. Method according to any one of the claims 1 to 4, wherein cement comprising construction or building materials is selected from the group consisting of panels, pipes, corrugated roofing sheets, flat sheets, roofing tiles and water tubes.
6. Method according to any one of the claims 1 to 5, wherein mechanically reducing the particle size in step (a) results in particles with a size distribution D95 between 10 pm to 80 pm, preferably a D95 of 20 pm to 50 pm.
7. Method according to any one of the claims 1 to 6, wherein mechanically reducing the particle size in step (b) results in particles with a size distribution D95 between 0.5 pm to 5 pm, preferably a D95 of 1 pm to 3 pm, more preferably a D95 of 1 pm to 2 pm.
8. Method according to any one of the claims 1 to 7, wherein step (b) further comprises the addition of one or more compounds selected from the group consisting of pH modulating compounds, metal precipitating, or binding, compounds and carbonate bound alkali or earth alkali metals.
9. Method according to claim 8, wherein pH modulating compounds are selected from the group consisting of NaOH and KOH.
10. Method according to claim 8 or claim 9, wherein metal precipitating compounds are selected from the group consisting of sulphur, citrates and chelating agents.
11. Method according to any one of the claims 1 to 10, wherein, after step (b), the slurry is subjected to phase separation, or sedimentation, and optionally further processing, yielding from the liquid phase calcium carbonate (chalk) and/or calcium sulphate (gypsum) and from the semi-solid phase silica bound material suitable for use in geopolymers.
12. Method according to any one of the claims 1 to 11, wherein, in step (a), mechanically reducing the particle size of the slurry to less than 100 pm is performed in a ball mill for 0.5 to 30 hours.
13. Method according to any one of the claims 1 to 12, wherein, in step (b), mechanically reducing the particle size of the slurry to less than 10 pm is performed in a bead mill for 0.5 to 10 hours.
14. Method according to any one of the claims 1 to 13, the method comprises the steps of: al) mechanically reducing cement comprising construction or building materials to pieces of 5 to 20 cm; a2) mechanically reducing the pieces of step (al) to a powder with a particle size of less than 1.5 mm; a3) suspending the powder of step (a2) in water, wherein the mass ratio cement comprising construction or building materials to water is from 1 : 1 to 1:50; a4) mechanically reducing the particle size of the slurry of step (a3) to less than 100 pm;
bl) heating the slurry obtained in step (a4) to a temperature between 60°C to 99°C during 1 to 5 hours; b2) mechanically reducing the particle size of the slurry of step (bl) to less than 10 pm.
15. Method according to any one of the claims 1 to 14, wherein processing cement comprising construction or building materials comprises destruction of hazardous silica containing fibers selected from the group consisting of asbestos, glass wool, rock wool, chrysotile asbestos, crocidolite asbestos, amosite asbestos, tremolite asbestos, actinolite asbestos, and anthophyllite asbestos, preferably chrysotile asbestos and/or crocidolite asbestos.
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Citations (2)
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JP2000271561A (en) * | 1999-03-26 | 2000-10-03 | Asano Slate Co Ltd | Method for separating asbestos from waste of asbestos- containing fiber reinforced cement panel, method for detoxifying separated asbestos, method for producing fiber reinforced cement panel reutilizing detoxified asbestos and fiber reinforced cement panel |
KR102263613B1 (en) * | 2019-07-31 | 2021-06-10 | 한국기술교육대학교 산학협력단 | Detoxification of asbestos by mechano-chemical treating method |
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JP2000271561A (en) * | 1999-03-26 | 2000-10-03 | Asano Slate Co Ltd | Method for separating asbestos from waste of asbestos- containing fiber reinforced cement panel, method for detoxifying separated asbestos, method for producing fiber reinforced cement panel reutilizing detoxified asbestos and fiber reinforced cement panel |
KR102263613B1 (en) * | 2019-07-31 | 2021-06-10 | 한국기술교육대학교 산학협력단 | Detoxification of asbestos by mechano-chemical treating method |
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