CZ2013972A3 - Asbestos processing method - Google Patents

Abstract

A process for treating asbestos is described, wherein an asbestos or asbestos product is mixed with a geopolymer dispersion by geopolymer precursor forming a geopolymer matrix, i.e., aluminosilicates capable of hydrolysis in an alkaline aqueous solution and subsequent re-curing into an insoluble solid. water, wherein the precursor is molecularly linked to the surface of the asbestos fibers, or asbestos fibers in the order of micrometers, and less dissolved.

Description

Method of asbestos processing

Field of technology

The invention relates to a process for treating asbestos or asbestos products to form a linear structure of a geopolymer matrix, for the disposal and utilization of asbestos and its wastes in a high-strength composite in a mixture with a geopolymer matrix.

Prior art

At present, no technology is known which would dispose of asbestos and at the same time make economical use of asbestos-containing material. The harmful properties of asbestos, including its waste, are treated as hazardous waste without further use. Loose asbestos fibers in the form of dust cause serious health problems and are carcinogenic when penetrating the body.

The object of the present invention is the use of asbestos resp. asbestos dust as part of a new usable material with useful properties obtained by the addition of asbestos, where, on the contrary, the presence of asbestos is beneficial for its ability to effectively modify the final microstructure of the product.

The essence of the invention

The present invention relates to a process for the treatment of asbestos. The invention is based on the fact that asbestos or an asbestos-containing product is mixed with a geopolymer dispersion by coating its particles with a geopolymer precursor forming a geopolymer matrix, i.e. aluminosilicates capable of hydrolysis in alkaline aqueous solution and subsequent re-curing into a water-insoluble solid. , wherein this precursor is molecularly bound to the surface of the asbestos fibers, or asbestos fibers of the order of microns and less in thickness are dissolved therein. The geopolymer dispersion forms a plasticizer, allowing dust-free comminution of asbestos.

The aluminosilicates of the geopolymer matrix are selected from the group consisting of metakaolinite as a major component of calcined kaolins, clays and shells, fly ash, slag, natural pozzolans and raw materials containing aluminum and / or amorphous SiO2 and combinations thereof in admixture with amorphous

SiO 2 in solid phase or solution with alkali hydroxides and solutions of dissociated alkali salts. The aluminosilicates of the geopolymer matrix may further contain hydroxides and alkaline earth salts or minerals.

The asbestos dust is processed in such a way that it is inhibited in the geopolymer matrix, so that it cannot be released even after the product has been crushed, because it has become part of its structure and is no longer a free microscopic fiber. This transforms harmful asbestos into a part of usable new material with exceptional properties, obtained by the addition of asbestos and where, on the contrary, the presence of asbestos is beneficial for its ability to effectively modify the final microstructure of the product. Linearly organized interconnections of clusters resulting from polycondensation of starting materials lead to an increase in the flexibility and strength of the product.

The linear structure of the geopolymer matrix at the micro to nanostructural level of formation is formed depending on the size of the starting asbestos fibers, which surface or completely hydrolyze during alkaline activation by geopolymer precursors and become part of the resulting molecular structure during the geopolymer to solid conversion phase. strength and flexibility of the resulting geopolymer.

The presence of asbestos imparts high strength to the geopolymeric substance, it has been verified that in the geopolymer matrix the originally usual amorphous arrangement of clusters is converted to linear by the addition of asbestos fibers. The carrier of the increased strength of the newly formed solid, which is a product of the synthesis of asbestos and its products with precursors of hitherto known geopolymers, is not the fibers of the starting asbestos minerals but the linearly modified structure of the resulting matrix at the micro- to nanostructural level. The hitherto usually amorphously arranged geopolymer matrix, which is characterized by low mechanical strength, has been converted into a much stronger arrangement, with a markedly linear orientation, leading to up to 100% higher compressive strength due to fusion of needles of mineral crystals present in asbestos and its products with conventional geopolymer precursors.

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Examples of embodiments of the invention

A suitable method of processing asbestos is to grind the moistened asbestos raw material into small particles and further grind with a geopolymer precursor in a powerful mixer. The resulting plastic is extruded or pressed according to its stiffness. Content

Asbestos in the resulting geopolymer is up to 39% by weight.

The results of observing the sections with an electron microscope confirmed that the samples with a lower asbestos content after curing of the geopolymer are completely converted to geopolymer. The higher asbestos content requires a demanding incorporation technology, because originally the dispersion becomes a plastic to a rigid mass. The filling limit is still 62% of asbestos in the dry matter of the final product. For higher values, an enormous dilution of the geopolymer matrix with water would have to be used.

The degree of detoxification or perfect incorporation is determined by the method of mixing. Thus, in the case of a lower filling content (around 10%), mixing is common, in the case of a higher content (above 20%), for example, a screw press and extrusion between rollers. At higher contents (above 40%) calendering or similar extrusion between rollers can be used, preferably in shear, and at extreme contents above 50%, only high-pressure pressing works in the experiment using a hammer in a small space defined by hard-walled walls. Although the material to be processed was already almost dry crumb, liquefaction occurred under this stress and the mass containing 62 g / s was extruded into leaks and formed a thin hard edge after curing. At the same time, however, with increasing content, it was necessary to increase the dilution and thus reduce the likelihood of detoxification.

Examples of asbestos composites with geopolymer binder:

Example 1

Disposal of asbestos.

A substance with a maximum asbestos content which is still fixed with a sufficient efficiency of 95% to prevent the asbestos from being washed out with water. The product is fittings for landfilling as ordinary construction waste. Composition of the composite e Jimoth® asbestos, 40% by weight of geopolymer binder.

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Example 2

Recycling of asbestos into building materials.

Material with asbestos content, which is fixed with an efficiency of 9S |%, enabling safe π machining by cutting. The product is fittings with a toughness of 1.2 times and a compressive strength of 1.5 times higher than the geopolymer binder without asbestos alone. Composite composition 35 wt% asbestos, 65 wt% geopolymer binder. Use of fittings: building materials with high mechanical strength.

Example 3

Asbestos recycling for use as board construction material.

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A material containing asbestos, which is fixed with an efficiency of 9S |%, enabling safe machining by cutting. The product is plate fittings with increased flexibility, allowing reversible deformation, which is a deflection 1.9 times higher than the geopolymer binder itself without asbestos. Composition of the composite 3% by weight ^of asbestos, 70% by weight ^of geopolymer binder. Use as a board building material for vertical structures with fire protection.

Example 4

Asbestos recycling for use in construction.

A material containing asbestos, which is fixed with an efficiency of 9S / o, allowing safe machining by cutting. The product is a lightweight thin-walled hollow fitting, enabling filling with concrete or other suitable filling, eg structural foam, soil, loose thermal insulation, reinforced and unconsolidated rubble and other suitable waste granulate. Composition of composite 25 (asbestos, 75 .mu.m) of polyol polymeric binder. Usage: lost formwork, foundation of buildings.

Example 5

Asbestos recycling for use as tubular material.

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Material with an asbestos content, which is fixed with an efficiency of 99%, allowing safe machining by cutting. The product is a lightweight hollow fitting formed by extrusion through a core. Composition of a composite of 20 'asbestos, 30 .mu.m, and 50 .mu.m of a geopolymer binder. Use for drawing tubes of any shape and size.

Example 6

Asbestos recycling for use as a construction material for horizontal building structures.

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Material with an asbestos content, which is fixed with an efficiency of 99%, allowing safe machining by cutting. The product is a construction profile for horizontal structures of appropriate load-bearing capacity created by extrusion. The composition of the composite is 15% asbestos, 35% sand and 50% geopolymer binder. Use for reinforcements of any cross-sectional shape as a replacement for iron beams in certain loads.

Example 7

Asbestos recycling for use as a construction material for ceiling structures.

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Material with an asbestos content, which is fixed with an efficiency of 99%, allowing safe machining by cutting. The product is hollow fittings designed for ceiling mounting. The composition of the composite is 15% by weight of asbestos, 45% by weight of sand and 40% by weight of geopolymeric binder.

Example 8

Asbestos recycling for use as facade panels.

Material with an asbestos content, which is fixed with an efficiency of 99%, allowing safe machining by cutting. The product is a lightweight thin-walled board with long-term resistance to exposure to weather conditions. The composition of the composite is ¹ % by weight of asbestos, 50% by weight of sand and 35% by weight of polymeric binder. Use as a replacement for metal and laminate facade boards made of organic resins.

Example 9

Asbestos recycling for use as floorboards.

IN

Material with an asbestos content, which is fixed with an efficiency of 99%, enabling safe machining by cutting. The product is a lightweight thin-walled floorboard for dry reconstruction of buildings. Composition of the composite 12% by weight of asbestos, 50% by weight of sand and 38% of geopolymeric binder. Use as a replacement for chipboard and cement floorboards.

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Example 10

Asbestos recycling for use as a laminate composite.

A material containing asbestos, which is fixed with an efficiency of 99%, allowing safe machining by cutting. The product is a thin-walled three-dimensional hollow object of any shape created by applying or pressing to a negative or positive form, the so-called hoof. Composition of the composite 15'hmoth. ^{about 4-} asbestos, 25% by weight of sand and 60% by weight of a polymeric binder. Use - non-flammable replacement of plastics eg.

in the automotive industry.

'J ^J ' / ú /.-- / L -'—— x ú —- 7 for reinforcing geopolymer materials applied in situ. /

Asbestos-reinforced material, which, after curing, is fixed with an efficiency of 99%, enabling safe any handling, including machining. The product is a plastic material for sealing, grouting, graveling, modeling, erasing, gluing, molding, anchoring and supplementing building, monumental, artistic, stone, wooden, metal and ceramic works. Composition of a composite of 10% imbazbest, 30% sand and 60% geopolymer binder. Use - self-hardening plastic non-flammable material.

Claims (4)

PATENT CLAIMS A process for the treatment of asbestos, characterized in that the asbestos or asbestos-containing product is mixed with a geopolymer dispersion by coating its particles with a geopolymer precursor forming a geopolymer matrix, i.e. aluminosilicates capable of hydrolysis in alkaline aqueous solution and subsequent re-curing to solid water-insoluble substances, this precursor being molecularly associated with the surface of the asbestos fibers, or asbestos fibers of the order of microns and less in thickness being dissolved therein. Process according to Claim 1, characterized in that the geopolymer dispersion forms a plasticizer which allows dust-free comminution of the asbestos. The method of claim 1, wherein the geopolymer matrix aluminosilicates are selected from the group consisting of metakaolinite as a major component of calcined kaolins, clays and shells, fly ash, slag, natural pozzolans, and raw materials containing aluminum and / or amorphous SiO 2, and their mutual combinations in a mixture with amorphous SiO 2 in solid phase or solution with alkali hydroxides and solutions of dissociated alkali salts. The method of claim 3, wherein the geopolymer matrix aluminosilicates further comprise alkaline earth hydroxides and salts or minerals.