FR2578833A1 - Process and plant for the preparation of a powdered product obtained from waste "E" glass fibres for textile fibres - Google Patents

Abstract

The plant for the preparation of a powdered product obtained from waste "E" glass for textile fibres may comprise a station 7 for chopping waste glass fibres previously subjected to a treatment for removing binders and adhesives, at least two consecutive pairs of Archimedes' screws 10, 11, of variable pitch, a dry vibrating screen 13, at least one ball mill 17 fed from a silo 16, a first separating cyclone 18 and batteries of knockout cyclones 19 for discharging the powder into the silos 20. The product obtained by means of this plant can be recycled or, depending on its particle size, be used for the preparation of ceramic frit mixes or in the composition of ceramic and vitreous sanitary biscuitware.

Description

PROCESS AND INSTALLATION FOR THE PREPARATION OF A MATERIAL
POWDER OBTAINED FROM WASTE FIBERGLASS "E"
FOR TEXTILE FIBERS.

The present invention relates to a process and an installation for the preparation of a powder product, obtained from waste glass fibers "E" for textile fibers, having a homogeneous composition and with a particle size of less than 1200 μm.

As is known, for certain particular applications, by subjecting the molten glass coming from the ovens to an extrusion through the orifices of particular dies, filaments are obtained which are then surface treated with binders and / or glues containing thermoplastic and thermosetting resins, such as for example latexes, phenolic resins and the like.

 It is also known that during said operations, for reasons of irregularity in the flow of the molten product, rupture of the filaments, imperfections of the filaments, an imperfect cut of the filaments or even during their transfer, their packaging and upon receipt or storage, part of the production must be rejected for non-compliance with development and measurement standards, for successive operations.

Due to the fact that said glass filaments are coated with the above-mentioned binders and / or glues, they cannot currently be recycled in the preparation process.

Taking into account the fact that the importance of said waste or rejects varies between around 10 and 15% of production, it is obvious that it constitutes a serious loss and a significant increase in the cost of the product.

Another serious disadvantage is due to the fact that said unusable waste must be disposed of in any way or, in any case, removed from the production installations.

The solution currently most used is that of transporting and abandoning said unusable waste in landfills.

Apart from the fact that it constitutes a further increase in costs due to the costs of transporting waste, this solution represents a serious waste of raw material and the cause of high pollution of large plots of land and neighboring areas.

In order to eliminate said drawbacks and to be able to reuse the products made up of said glass fibers, certain particular methods have been studied in recent years.

They essentially consist in grinding the filaments and / or glass bars and in a successive series of heating operations under controlled heat treatment conditions.

The filament and / or glass rod fragments are initially heated to a temperature sufficient to remove the moisture present therein. They are then heated to a temperature sufficient to volatilize the organic components of the binders and / or glues present on their external surface, and finally they are subjected to thermal conditions suitable for allowing the incineration of the surface substances present on said fragments, in keeping the glass below its softening point.

The glass fragments thus treated are then subjected to a possible successive grinding operation, before being returned to the entry of the furnaces.

These methods, although sufficient for the direct recovery and recycling of certain types of filaments and / or glass rods produced in continuous production facilities for filaments and / or bars, nevertheless have certain drawbacks and limitations
In particular, for the above-mentioned succession of heating of the glass fragments, ovens are used in which the energy consumption has a non-indifferent influence on the final cost of the product recovered.

Another drawback is due to the fact that the recovery product obtained with the above-mentioned processes can only be reused for recycling in installations for the production of filaments and / or glass rods, so that they can be used economically and rationally, the recovery units must be installed in the same areas as the production facilities for filaments and / or glass rods.

Another drawback which results from the use of the recovery product limited to the aforementioned recycling, is due to the fact that the final cost of the regenerated product does not sufficiently justify the use of capital for the realization of said installations or recovery units.

Yet another drawback is due to the fact that the regenerated product is present, at the end of the preparation, in the form of tiny fragments of glass, on the surfaces of which persistent cutting edges and protuberances persist.

The configuration of said powdery fragments of glass constitutes a discomfort and a serious danger for the personnel assigned to the control and handling of the installations, and to that which is assigned to the transport, storage and loading of the ovens.

The object of the invention is to provide a method and an installation for the preparation of a powdered product obtained from waste glass filaments, in particular glass filaments of type "E". for textile fibers which do not have the aforementioned drawbacks.

More particularly, the object of the invention is to provide a process and a corresponding installation for obtaining a powdered product free of sharp edges, tips and cutting parts which can be used not only in the regeneration of filamentary glass fibers of the type "E" for textile fibers, but also in other applications such as, for example, ceramic frits, mixtures for ceramic frits, supports for ceramic or vitrossanitary cookies and the like.

Another objective of the invention consists in making it possible to have a process and a corresponding installation for the transformation and recovery of glass waste, of type "E", which make it possible to obtain a pulverulent final product of particle size very fine, with rounded surface and uniform chemical composition, which can be reused directly in the furnaces for the production of "E" type glass, as a raw material, or which can also be used for other applications.

Yet another objective consists in providing a process and a corresponding installation for the transformation and recovery of "E" type glass waste which can be indifferently used directly in the installations for producing the same glass, or which can be placed in a any other preferred post or location, and such that the structures and components of the installation are such as to guarantee a final product of high quality and decisively advantageous cost.

Yet another objective is to provide a method and a corresponding installation which make it possible to easily and completely remove all the components of the binders and / or adhesives present on the external surfaces of waste filaments, whether by a natural method or by mechanical and / or thermal actions, significantly limiting the energy consumption required.

According to one aspect of the invention, the proposed objectives and others still can be achieved by a method which consists in subjecting the type “E” glass fiber waste to textile fibers to the following treatments -a ) elimination of the binders and / or glues present on
the outer surface by a natural process or by
mechanical and / or thermal actions -b) a fragmentation of the waste -c) a reduction in powder of the fragmented product and -d) a separation and a felling of the granulomé powders
sort determined.

The removal of binders and / or glues from the surfaces of the waste can be carried out by prolonged exposure to atmospheric agents with a possible periodic spraying of water, or by a method of solubilization by the liquid route, or also by a sublimation process. thermally.

According to one aspect of the invention, these and other objectives are obtained with a palpable powder prepared from glass fiber waste of type "E" for textile fibers, having a homogeneous composition and a particle size less than 1200 Vm and up to a few vm, and free of sharp edges or angles, tips and cutting parts. The fragmentation of waste, which can precede or follow the phase of elimination of binders and / or glues, is carried out by means of a chainsaw with inclined blades and pairs of Archimedes screws with variable pitch coupled in a rotational movement synchronized.

Powder reduction is carried out by a ball or ball mill, while the successive phases of separation and extraction of powders are carried out by conical separators with blades, at variable speeds and, respectively, by a plurality of batteries of cyclone fallers.

For a better understanding of the process and of the installation for the transformation and recovery of "E" glass waste for textile fibers, which is the subject of the invention, certain embodiments will be described below in more detail. , for information but not limiting, with reference to the accompanying drawings in which
Figure 1 shows the diagram of an installation of
transformation and recovery of glass waste
"E", which uses the natural exposure method to
atmospheric agents for the removal of binders
and / or surface adhesives
Figure 2 shows a variant of the installation
using a method of removing binders and / or
surface adhesives, using a solubilization process
liquid; and
Figure 3 shows another variant of the installation
lation corresponding to the method of elimination of
surface binders and / or adhesives according to the
thermal sublimation.

Figure 1 illustrates the basic and preferred scheme of the invention, in which the binders and / or surface adhesives are removed naturally
It has indeed been able to verify that said binders and / or surface adhesives essentially constituted by thermoplastic and thermosetting resins such as latexes, phenolic resins and the like, degrade by exposure to air in a relatively short time and become soluble in water.

Thanks to these characteristics, the filamentary glass waste of type "E" is piled up in outdoor areas 1 and is left exposed to atmospheric agents for a certain period of time, preferably extended, such as for example about one year.

During this period, the alternations of the seasons, rain, sun, fog, snow, frost exert a continuous surface washing action of the glass fibers, until significantly reducing said binders and / or negligible amounts. or surface adhesives
To make the degradation and elimination of said resins more effective, it is possible to periodically water the accumulations of glass waste, and in particular during periods of heat, with water sprays 2.

In special cases, to speed up the glass fiber washing cycle, the water spray may be mixed with caustic soda or, in any way; with alkaline-based products.

When the filamentary glass waste "E" has undergone surface washing, it is sent to a hopper 3 under which a first conveyor belt 4 regulates their discharge rate on the conveyor belt 5, provided with a system of claws 6. Said the main purpose of the claws is to spin the filament fibers from the strip 4, to orient them in the longitudinal direction and to send them in the first cutting phase 7, before a possible first intermediate phase 8 of elimination of possible foreign bodies .

The cutting phase 7 is preferably carried out using at least one chainsaw or shears with inclined rotating blades, which makes it possible to fragment the glass fibers "E" into fragments whose average length is a few centimeters.

Subsequently, said fragments pass over a conveyor belt 9 which feeds two pairs of Archimedes screws with variable pitch, arranged in succession, 10 and 11. The rotational movement of each pair of Archimedes screws 10 and 11, coupled and in synchronized movement, allows an additional reduction in size of the fiber fragments.

In particular, and by way of example, the first pair of variable pitch Archimedes screws may have an initial pitch of approximately 350 mm and a final pitch of approximately 150 mm, while the second pair may have a pitch initial about 150 mm and a final pitch of about 50 mm.

On leaving the screw 11, the glass fiber fragments have dimensions varying from 1 to 10 mm, with a maximum diameter of approximately 200 μm. From the Archimedes' screws, the product in fragments is then sent, by means of a conveyor belt 12, to a dry vibrating sieve 13, which retains any foreign bodies still present in said product, to discharge them in 30 Then, the product is sent to storage 14, waiting to be subjected to the consecutive development phases.

From the storage 14 and by means of an elevator 15, the product is loaded into silos 16, fitted with vibrators which feed at least one ball mill 17.

The grinder 17 and the corresponding balls or balls are made of synthetic alumina of high specific weight, so as not to pollute the ground product.

From the grinder 17, the product is sucked and mixed with the air by means of a powerful fan through pipes, preferably made of antiabrasive rubber or synthetic alumina. The product then passes through a first separation cyclone 18 provided with a conical paddle separator which, by speed regulation, can select the particle size of the product.

The product with a higher particle size, between 1200 and 250 μm and discarded by the cyclone 18, can be returned to the mill 17 for further grinding, or can be collected for use for particular applications.

The finest parts of the product progress through the cycle and enter batteries of cyclone fallers 19, which collect the powder with an average particle size between 250 and 10 μm and discharge it into silos 20.

The air and the products with a particle size of less than 10 vm pass through a sleeve filter 21, swept by compressed air.

In said filters, all the particles of product with a particle size less than or equal to 10 μm are slaughtered, then collected either in the same silos or in separate silos.

The installation thus arranged consequently authorizes the obtaining of a ground product in powder of single average particle size or else three separate classifications and extractions of products of differentiated particle size, and precisely - from 1200 to 250 vm on the return of the cyclone 18 - from 250 to 10 μm from the fall-down cyclones 19; and - 4 10 vm from the sleeve filter 21.

To improve the grinding obtained in the ball mill 17, to eliminate any moisture in the product and to completely eliminate any residues of binders and / or surface adhesives on the ground products, the interior of said mill can be heated to about 100-110 0C.

Said heating is preferably carried out by supplying the burners with liquefied petroleum gas (G.P.L.) until a dry product is obtained.

For combustion, it is also possible to reuse part of the purified hot air leaving the sleeve filter 21, which has a temperature of around 60-700C.

The product obtained according to the process described above is in the form of a homogeneous, palpable powder.

The homogeneity of the powder is obtained as a direct consequence of the homogeneity inherent in waste glass fibers "E", from which it derives.

A typical example of the composition of the powdered product obtained can be as follows
Si 2 Silic Anhydride 54.5%
A1203 Aluminum oxide 14.5%
Ca 0 Calcium Oxide 21.0%
Mg 0 Magnesium Oxide 0.04%
B203 Boric Anhydride 8.00%
Na20 Sodium Oxide 0.4%
Fe203 Ferric Oxide 0.15%
Ti O2 Titanium Oxide 0.20%
R2 O Potassium Oxide 0.30%
Naturally, the abovementioned percentages may undergo small variations, within limits determined by the tolerances imposed by the manufacture of "E" type glass fibers.

In the said composition, the quantity of the residues of binder products and / or glues turns out to be negligible.
By grinding by means of rotary ball mills 17 the grains of the powdered product have a perfectly rounded and even surface.

This characteristic guarantees optimum maneuverability of the product while avoiding the unpleasant drawbacks encountered in traditional glass fiber processing plants in general.

The product can indeed be easily handled without risk of tearing or cutting.

Similarly, any particles suspended in the air in the work premises, escaping if necessary during purification, also do not constitute a danger for the personnel assigned to the production and the confection of the product. .

As already mentioned above, the powdered product can have a particle size varying from 1200 μm to a few μm and can be selected according to its size according to the use for which it is intended.

By way of example, the three types of powder mentioned above, having different particle sizes, can be used in the following sectors - from 1200 to 250 vmB the powder can be used directly in type E glass fiber regeneration plants "- from 250 to 10 pm, the powder can be used for the preparation of mixtures of ceramic frits; - 4 10 vm, the powder can be used in the direct preparation of ceramic frits, in support additions for ceramic and vitrossanitary biscuits and the like.

In the use for the regeneration or recycling of E "glass fibers, the powdered product allows easy mixing with the raw materials used in the glass production industry, allows optimal homogenization of the components and saves sensitive of raw material.

In its use in the ceramic industry, the powdered product can be used, directly mixed in variable percentage, as ceramic frit, or as enamel on tiles or on any types of ceramic or sanitary products, or it can also be enameled or melted on ceramic cookies.

In a different way, it can also be used as a raw material in the preparation of ceramic frits, i.e. it can be used, depending on its components, mixed and melted with other fundamental components for ceramic frits.

By way of example only, the powdered product can constitute a fundamental element of frits containing boron, alumina, calcium and silica.

The product is also used effectively in ceramic or X-ray or ceramic supports or cookies.

In this case, thanks to its characteristics and its granulometry, it also allows an energy saving which is not indifferent to the fact that the cooking temperature, in single-fired ovens, can be lower than about 400C compared to that which is currently necessary. One of its other fundamental characteristics is that it significantly increases the antifreeze of the mixtures of which it is a component.

As can be understood from the above, the powdered product obtained by the process according to the invention, apart from the fact that it provides significant savings in raw material in the production of "E type glass fibers. "and that it appreciably decreases the pollution of large areas of land, finds a useful application in other branches of industry and, in particular, in the ceramic industry, by making it possible to lower the costs of products, limit energy consumption and produce high quality products.

FIG. 2 represents an installation for the removal of binders and / or surface adhesives by liquid solubilization.

In this case, the installation shown in FIG. 1 is modified in the intermediate part after the pair of Archimedes screws 10 and 11. The ground product, leaving said screws, is sent, by means of conveyor belts 22, to d 'other pairs of inclined Archimedes screws 23 filled to the brim with water, possibly containing caustic soda or any other alkali.

During its journey, the product undergoes strong stirring and friction between the screw propellers and the water or the aqueous solution, until it is discharged from the upper part which is completely free of the thermoplastic and thermosetting resins present on its surface.

Above, the screw 23 is continuously sprinkled with the same liquid product, coming out of sprayers 31.

During said treatment, it is verified that the maximum concentration of the binding and / or glue products is negligible.

The product discharged from the Archimedes screws 23 is sent, by means of a conveyor belt 24, to a vibrating screen 25, subjected to sprinkling with water 34, capable of retaining any foreign bodies present in the crushed product which is discharged in 32.

The vibrating screen 25 has two superimposed classification lattices, the first, coarse, to retain any foreign bodies and the second, with mesh sizes of about 1.5 mm, collecting the product and draining it before send to storage 44, by means of the conveyor belt 33 waiting to be subjected to the consecutive preparation phases, identical to those which are already described above.

The water discharged from the second mesh of the vibrating screen 25 is sent to a rotary settling tank 26 from which the product particles escaped from said mesh are recovered.

This product is also sent to storage 14, before draining, to then be sent to silos 16 for further operations, according to the cycle shown in FIG. 1.

The silo (s) are preferably treated on the interior surfaces, by vitrification processes, so as not to pollute the product produced.

The complete drying of the product is carried out in the ball mill (s) 17, heated to a temperature of 1001100C.

The process for the liquid solubilization of binders and / or surface adhesives can be combined with that of storage 1 of the waste, with or without any water sprays 2, or can be implemented in direct succession with the production facilities. "E" type glass for textile fibers.

FIG. 3 represents the installation for the removal of binders and / or surface adhesives by thermal sublimation. In this case, the installation shown and described according to the diagram in FIG. 1, undergoes modifications in its intermediate part after the silos 16.

In particular, the product discharged from the silo (s) 16 is sent to at least one rotary oven 27 supplied with liquefied petroleum gas, inside which is reached a maximum temperature of about 600 C, sufficient to eliminate said surface binders and / or adhesives.

In order to avoid granulation phenomena due to electrostatic charges between the smallest particles of the product, the discharge mouth of the oven is directly coupled to the feed mouth of the mill 17.

In addition, at the head of the rotary oven 27, a heat exchanger 28 is mounted capable of lowering the temperature of the fumes from approximately 6000C to approximately 70eC to overcome the large expansions which could occur in the mill and to preserve the antiabrasive coating. The exchanger 23 is used to heat the combustion air for the burners of the oven 27.

The product treated in the oven (s) 27 goes directly to the grinding treatment carried out by one or more ball mills 17, already described and shown in FIG. 1.

This third solution, using the sublimation process by thermal route for the removal of binders and / or surface adhesives, can also be used both in the presence of the waste storage process 1, with or without any water spraying 2, than being used in direct succession with E'i E type glass production facilities for textile fibers.

Although the invention has been described and represented with reference to preferred embodiments, it is obvious to specialists in the technical sector considered that various modifications can be made to the process and to the components without departing from the scope and the spirit of the invention.

Claims (14)

Patent claims  1. Method for preparing a powdered product obtained from glass waste "E" for textile fibers, characterized in that it consists in subjecting glass fiber waste of type '9E "for textile fibers with the following treatments -a) elimination of the binders and / or glues present on  the outer surface by a natural process or by  mechanical and / or thermal actions -b) fragmentation of waste -c) powdering of the fragmented product; and -d) separation and felling of granuloma powders  sort determined.  2. Method according to claim 1, characterized in that the treatment for removing binders and / or glues comprises a prolonged exposure of the waste to atmospheric agents with a possible periodic spraying of water.  3. Method according to claim 2, characterized in that the water spray contains caustic soda or alkaline products.  4. Method according to claim 1, characterized in that the treatment for removing binders and / or adhesives comprises solubilization in water or in alkaline solutions.  5. Method according to claim 1, characterized in that the treatment for removing binders and / or adhesives comprises solubilization at a temperature not higher than 6000C.  6. Installation for implementing the method according to any one of the preceding claims, characterized in that it comprises -a) a cutting station (7) of glass fiber waste from  type "E" for textile fibers, previously subjected to a  treatment for removing binders and / or glues,  said cutting phase comprising at least one section  neuse or shears with inclined rotating blades -b) at least two pairs of Archimedes screws (10, 11) kept  variable pitch cut for later fragmentation  fiber fragments; -c) a dry vibrating screen (13); -d) at least one ball mill (17) supplied from a  silo (16) fitted with vibrators -e) a first separation cyclone (18) provided with separa  conical padded seeders; and -f) batteries of cyclone fallers (19) for discharging  storage of the powder in silos (20).  7. Installation according to claim 6, characterized in that the ball mill (17) is heated to 100-110 C.  8. Installation according to one of claims 6 and 7, characterized in that it comprises a sleeve filter (21) swept by compressed air, for the removal of product particles having equal dimensions or less than 10 pm.  9. Installation according to any one of claims 6 to 8, characterized in that between the pairs of Archimedes screws (10, 11) and the ball mill (17) are inserted: pairs of Archimedes screws (23) inclined, filled to the brim with water, preferably alkaline, in which the product is subjected to strong stirring and friction, a vibrating screen (25) provided with two superimposed classification lattices, one for retaining foreign bodies, the other having mesh of about 1.5 mm to collect the product, and a rotary settling tank (26) into which the water leaving the second mesh of the vibrating screen (25) flows .  10. Installation according to any one of the claims 6 to 9, characterized in that at the mouth of the ball mill feeder (17) is coupled a rotary kiln (27) heated to a maximum temperature of 6000C by through a heat exchanger (28).  11. Product obtained from type E glass fiber waste for textile fibers, according to the method according to one of claims 1 to 5, characterized in that it consists of a palpable powder of homogeneous composition having a particle size less than 1200 Um, free of sharp angles, tips and cutting parts.  12. Product according to claim 11, characterized in that the powder has a particle size between 1200 and 250 Vm.  13. Product according to claim 11-, characterized in that the powder has a particle size between 250 and 10 pm.  14. Product according to claim 11, characterized in that the powder has a particle size less than or equal to 10 vm.