WO2013156843A1

WO2013156843A1 - Process for manufacturing a composition of cement made of waste or virgin materials of various kind and composition of cement obtained therefrom

Info

Publication number: WO2013156843A1
Application number: PCT/IB2013/000715
Authority: WO
Inventors: Sergio Fregonese; Claudio Pelusi
Original assignee: Sergio Fregonese; Claudio Pelusi
Priority date: 2012-04-19
Filing date: 2013-04-17
Publication date: 2013-10-24
Also published as: BR112014024655A2; ITPN20120020A1

Abstract

Process for manufacturing a composition of cement made of waste or virgin materials of various kind, adapted to be used with the function of material having good thermal conductivity, particularly in the building industry, as self-levelling screed for covering the heating panels to be applied on to the floors of traditional type. Process utilizing component materials from which the metallic materials have been eliminated, and the aluminium has been eliminated or reduced up to a percentage lower than 1% by weight, by means of a specific de-aluminizing process. Also a composition of cement obtained with such manufacturing process is described.

Description

"PROCESS FOR MANUFACTURING A COMPOSITION OF CEMENT MADE OF

WASTE OR VIRGIN MATERIALS OF VARIOUS KIND AND COMPOSITION OF CEMENT

OBTAINED THEREFROM"

The invention relates to a process for manufacturing a composition of cement made of waste or virgin materials of various kind, adapted to be used with the function of material having good thermal conductivity, particularly in the building industry, as self-levelling screed for covering the heating panels to be applied on to the floors of traditional type, by using waste or virgin materials of common use. Furthermore, the invention relates to a composition of cement obtained by this manufacturing process.

At the present time, it is a custom to use self-levelling screeds of various kind for covering the heating panels to be applied on the floors, which are arranged on to the floors of the inhabited rooms and which are formed by ducts bent as a coil which are joined to each other and connected with their end portions to correspondent delivery and return ducts of water heating boilers, for circulating the hot water through such ducts and transmitting the heat into the room through the installed screed.

There are known in the commerce pre-mixed self-levelling screeds, which are constituted by dried sands with pre-established compositions, by binder materials for building industry including cement or calcium sulphate and specific additive materials of traditional type.

For using these type of self-levelling screeds, the users must comply with a set of severe standards regarding the preparation of the cast concrete.

In fact, it is indispensable that, in the first forty-eight hours after the concrete material has been cast in place, such casting must be executed completely protected by air-streams of any type and coming from any direction, as the presence of air-streams produces into the screed, owing to the well known phenomena of gripping and plastic shrinkage of the concrete which has been cast in place, some considerable cracks and damages which limit and sometimes may jeopardize the use of the same screed.

For preventing the presence of the air-streams when the self-levelling screed of concrete material is cast, it is necessary to close by means of cloths made of polyethylene all the openings (doors, windows, French windows) of the room in which such casting is effected, and this operation appears to be difficult to be performed in practice and requires always the availability of this closing material and the carrying out of further working phases, which involve considerable additional costs for the operators of this field. Furthermore, in the case in which the openings to be closed have considerable sizes, as for example in case of shopping centres and buildings with many openings, it would be practically almost impossible to close the same openings, so as to preclude the use of such materials for self- levelling screeds to be cast in place.

In order to avoid that such problems may arise, sometimes the mixtures of cement are added with fibres of ferrous or plastic materials, which tend to make easier the hardening of the material of screeds, by limiting the cracking phenomena thereof, as the fibres of such materials "absorb" a part of the traction strains which are developed into the mixture of cement when the same hardens. However, in practice the use of these additive fibres is much restricted for the self-levelling screeds, as these screeds must be very fluid and capable to slide onto the surfaces on to which they are cast, and therefore the presence of additive fibres, which normally are available from the suppliers with length and narrow sizes, strongly limits or even prevents the screed from freely sliding, by obstructing the sliding onto the same surfaces thereof.

The traditional self-levelling screeds are much used for covering the irradiating heating panels to be applied on to the floors, because they allow a good heating transmission.

However, for preventing that the above-specified problems may arise, these screeds must be reinforced with electrically welded or zinc-coated metallic nets, which if on the one hand serve to increase the resistance to bending stress, on the other hand are problematic for the workability of the screed, the thicknesses of which are generally very small. For obtaining self-levelling screeds, at the present time there are also used some compositions of cement applicable on to the floors of the inhabited buildings, which are constituted substantially by the combination and mixing of the following main components:

a) a first component formed by waste materials of various kind, ground in advance to have small- sized particles, and constituted preferably by wastes of heterogeneous plastic materials, wastes of elastomeric materials (rubbers, etc.), solid urban wastes, wastes of paper, cardboard, packages of various kind and with compositions of different materials, with extremely reduced or null percentages of metallic materials, of cellulosic-based materials and/or materials with polymeric plastic compositions (poly-coupled materials etc...), wastes of woods and woody materials of various kind, inert materials of various kind for building industry, glass remainders of various kind, b) a second component formed by binder materials for building industry of various kind as cements, limes, calcium sulphate of various kind, epoxy resins and/or acrylic resins of various kind, c) a third component formed by water,

d) a fourth component formed by organic and inorganic surfactant substances of per se known type, in which this composition is introduced into cement mixers or similar containers, and can be cast on to the floor by pumping it through delivering means, and can be also cast into moulds or formworks for forming pre-shaped panels of different shapes and sizes, to be applied subsequently into the relative application positions.

As above specified, for obtaining self-levelling screeds with the above described waste materials, it is necessary that extremely reduced or null percentages of metallic materials are present therein, and in particular the magnetic metallic materials are normally separated from the mass of waste materials being used by means of magnets with high power, which attract almost all the magnetic metallic materials, by discharging them into specific containers for making them available for different uses, whereas the aluminium contained into the waste materials, in the form of can reminders, packaging remainders of various type, poly-coupled material reminders, reminders of aluminized paint, etc., is not separated in that it is a not- magnetic material and therefore cannot be attracted by the magnets.

The presence of this aluminium in the interior of the composition of cement develops gaseous hydrogen, which reduces the specific weight of the same composition, and makes it brittle and not suitable to be applied onto the same floor by glueing, by creating also a porous insulating structure, which makes the self-levelling screed a bad thermal conductor material.

Moreover, such porous structure makes the same screed subjected to phenomena of differential shrinkage which, as above-specified, involve the formation of cracks and damages into the screed when the same is cast in place, which involve the drawbacks also specified previously.

The object of the present invention is to realize a process for manufacturing a composition of cement made of waste materials of the above described kind, or of virgin materials of the same kind, which is adapted to be used particularly for producing self-levelling screeds to be applied onto floors of inhabited buildings, by eliminating the presence of the aluminium contained into the waste or virgin materials, and by conferring to such composition of cement the characteristics of good thermal conductivity, which allow to cover the heating panels to be applied onto floors, and thereby obtaining the self-levelling screeds without the need to prevent the presence of air-streams and the consequent above-mentioned drawbacks involved by such presence, and furthermore by eliminating the need to use electrically welded or zinc-coated arc-welded nets as it occurs for the self-levelling screeds realized at the present time.

Besides, the invention relates to a composition of cement obtained by means of this manufacturing process.

This manufacturing process and this composition of cement are realized with the structural constructive characteristics substantially described, with particular reference to the attached patent claims and the following Figures:

-Fig.1 , which shows schematically some different forms of a material ground to have small-sized particles and used for obtaining the same composition of cement ;

-Fig.2, which shows schematically the various steps of the present process for manufacturing of the composition of cement according to the invention, for obtaining the de-aluminizing thereof.

The invention will be better understood from the following description, given by way of a not- limiting example only.

The composition of cement according the invention is intended to be used as good thermal conductor material, and is adapted to be used into inhabited buildings of various kind as self- leveling screed for covering heating panels to be applied on the floors of traditional type, by using waste or virgin materials of common use, in a manner to obtain a better and more effective heating of the inhabited buildings.

This composition of cement is substantially constituted by the following component materials: a) waste materials of various kind, ground in advance to have small-sized particles, and particularly wastes of plastic materials (ex. bottles of coloured, blue, transparent PET, small bottles, neolith, aggregates etc...) of heterogeneous type, wastes of elastomeric materials (rubbers, etc.), wastes of paper, cardboard, packages of various kind and with compositions of different materials (ex.

aluminium and plastic etc.), and cellulosic-based materials and/or materials with polymeric basic compositions (poly-coupled materials etc...), solid urban wastes, wastes of woods and woody materials of various kind, inert materials of various kind for building industry, glass remainders of various kind.

These materials may be used alone, namely by using at least any one of the materials of this kind, chosen at will, or they may be used combined to each other with different combinations and combinations at will of two or more materials of this kind. Likewise, instead of the using above- mentioned waste materials also virgin materials of the same kind may be used, even ground to have small-sized particles. Obviously, it's also possible to find an advantageous compromise about the use of the single waste or virgin materials, by utilizing in such case a mixture of waste and virgin materials, thus without departing from the protection sphere of the present invention. Moreover, it is to point out that the materials used for the present composition, either waste or virgin materials, must not include metallic materials or, in case in which they are including metallic materials as for example in the case of plastic materials containing metallic reinforcing fillers, these metallic materials must be included in extremely reduced percentages.

In this context, the metallic materials of magnetic type may be separated and eliminated by using some magnets with high power, whereas the aluminium contained into the metallic waste materials, in the form of reminders of cans, of packagings of various type, of poly-coupled materials, of aluminized paint, etc., is normally subjected to de-aluminizing treatments by means of separators with induced currents, which however are not able to eliminate completely the aluminium owing to the pulverizing due to the grounding treatment thereof, or by other grounds such as the glueing with the plastic thereof, as it happens for the poly-coupled materials. Hereinafter, the process with which the aluminium is completely or almost completely eliminated will be described ;

b) cement and particularly cement 32, 5 Portland or 42, 5 Portland ;

c) fine sand aggregate;

d) water ;

e) fluidizing or super-fluidizing additives ;

f) filler ;

g) ash.

The employed materials are used with the following proportions:

a) waste materials of various kind : about 30 +/- 10 Kg./m3 ;

b) cement type 32, 5 Portland or 42,5 Portland : about 400 +/- 50 Kg./m3 ;

c) half-dried sand aggregate : about 1200 +/- 150 Kg./m3 depending on the volume mass thereof ; d) water : water/cement ratio from 0,6 to 1, depending on the nature of the sand aggregates ;

e) super-fluidizing additives : from 0,5 to 1% by weight relative to the cement ; f) filler : from 50 to 150 Kg./m3 depending on the nature of sand aggregates, if sand aggregates have very fine grains the filler may be omitted ;

g) ash or mineral addition : up to 70 Kg./m3 depending on the nature of the sand aggregates.

The present composition of cement is obtained by mixing to each other at first the components of the point under a) with different and variable percentages thereof, and then by grounding in advance such components for obtaining small-sized particles of the same components, in the average range of 8 mm, which are subsequently introduced into concrete mixers and vehicles of other kind, from which they are then delivered on to the application sites.

All the ground waste materials of the composition of cement are subjected to a sanitary treatment, in order to destroy the bacterial floras and the various micro-organisms which are present into the same materials, by using ozone or enzymes reacting biologically with the bacteria and the microorganisms, in the sense to determine their "digestion", namely the total or partial inclusion thereof, or by using radiations of various kind (ex. ionizing, beta or gamma radiations on the fluid bed, etc.), or vapour, or by using high temperatures workings as for example the densifying, the sintering and the extrusion, or calcium oxide, or alkaline-earth oxides and hydrates, or hydrate oxides and alkaline carbonates.

In the case in which the existing bacterial charge is checked at the source, such sanitary treatment may not be effected.

As already specified, furthermore, the magnetic metallic materials and the aluminium contained into the waste materials of the point under a) are separated and eliminated in advance from the same waste materials and, in case of aluminium, from these waste materials at least a sample of the same materials is drawn, which is then subjected to the analysis which will be described, so as to determine if the materials contain or not contain aluminium and, in this latter case, for determining the percentage of aluminium contained into the same, in such a way that if such percentage is greater than a pre-established value, it is necessary to subject these waste materials to the de- aluminizing process which will be described, for using thereafter the same materials for obtaining the present composition of cement, and on the contrary if such percentage of aluminium is smaller than such pre-established value the materials needn't to be submitted to the de-aluminizing treatment and may be immediately used for the composition of cement.

Then, under these conditions, the self-levelling screeds obtained with this composition of cement allow to solve all the above mentioned problems.

Referring to the Fig. 1, the Figure 1 a shows the form of a fibre made of ferrous or plastic materials, which at the present time is prepared and made available for obtaining the current self- levelling screeds, by mixing a plurality of fibres of the same type with the cement material, and which however originates the above-described problems. On the contrary, in the Fig. lb there are shown the different forms of fibres or granules of waste or virgin materials of the point under a), which are used for obtaining the composition of cement according to the invention for the self- levelling screed.

As visible, such fibres or granules assume always an irregular scale-like shape, however having dimensions of 1 -2 cm. only and which are substantially bidimensional.

The shape of these fibres or granules mixed with the material of cement does not obstruct the flow and the flowability of the material poured into place and allows the same to be used with large quantities (from 20 to 60 Kg./m3), thereby creating a super-fibrous self-levelling screed having a strong isotropous behaviour.

Therefore, the formation of crazes or cracks is absent.

Besides, the inner framework formed by these fibres or granules allows not to use the electrically welded or zinc-coated net used and applied at the present time onto the irradiating heating panels of the heating applied on the floors.

The use of the flakes formed by such fibres or granules, allows also to operate with larger quantities of binder materials (cement), by involving however the decrease of the modulus of elasticity.

As a consequence thereof, it is possible to obtain more resistant surfaces without producing crazes or cracks into the screed of cement.

The composition of cement according to the present invention, which has characteristics of good thermal conductivity making it adequate for the use as covering of heating panels to be applied on the floors, is obtained with the proportions of the single component materials mentioned under the points a), b), c), d), e), f) and g).

The quantity of aluminium of the used and already ground plastic materials, in order that the same aluminium may be born in mind for the subsequent treatments thereof, and not rejected, should be lower than 1% by weight of the total weight of the used cement material, while the remaining magnetic metallic materials should be absent or almost completely absent.

For checking the compliance with these requirements, it is necessary to effect a suitable sampling and to submit the material of the composition of cement to be used to the following test, for determining the content of aluminium into the mixture of the waste plastic materials which are recovered.

METHODOLOGY OF PROOF

Drawing of a specimen to be analyzed.

The specimen to be tested must be representative and therefore drawn from many parts of the total quantity of the material of the composition of cement.

From 1000 Kg. of material, there must be effected at least 10 drawings with a ladle, each one of which having about 100 gr.

To perform the reduction of the specimen by means of subdivision into quarters, in accordance to the Standard UNI EN 932-2 paragraph 10.

REDUCTION OF THE SPECIMEN BY SUBDIVISION INTO QUARTERS

To put the lab specimen on to the working surface. To mix accurately the specimen with the ladle and heap it to form a cone and turning it upside - down so as to form another cone. To repeat three times this operation. When the cones are formed, put each filled up ladle on to the top of the new cone, in such a manner that the aggregate (the product) goes down from all the sides of the cone and be uniformly distributed and the various granules are adequately mixed to each other.

To flat the third cone which has been obtained, by beating the ladle with a vertical movement more times on to the top of the cone, up to form a flat heap having uniform diameter and thickness. To subdivide into quarters this heap flattened along the diagonals intersecting at right angle to each other.

To discard a pair of opposed quarters and to assemble the remainder with the ladle in a heap.

To repeat the mixing and the subdivision into quarters up to the requested test portion is obtained. Note: the use of a lamina or a wood cross or a metal strap which may be pressed against the heap, often simplifies the subdivision into quarters in the cases in that the material tends to segregate itself.

Preparation of the specimen to be analyzed.

The material obtained through the subdivision into quarters must be dried at 60° C for at least two hours and up to the specimen, between two weightings, has lost less than 0,2 % by weight. The results must be recorded and registered.

DETERMINATION OF THE TOTAL CONTENT OF ALUMINIUM INTO THE MIXTURE OF

RECOVERED PLASTICS.

Specimen analysis :

The mixed and dried specimen must be additionally sectionalised by the operator with the aim to obtain a final sample representative of the total. Therefore, a subdivision into quarters of the same specimen is performed, and thereafter, the selected part thereof is further reduced by means of a proper separating rotating machine.

To draw about 25 grams and put them into a porcelain bowl. By means of a Bunsen burner, to burn the plastic material, by looking for avoiding that a flame be developed ; a loss of weight of about 65% will be obtained. When this first calcining is ended, the obtained ashes must be put into a muffle at the temperature of 480° C for 4 hours. After this second thermal treatment, a loss of weight of about 89% is achieved.

At this point, the organic and/or synthetic materials have been eliminated in a large part by combustion and the obtained aluminium has oxidized to form Ah O3.

The obtained ashes are transferred into a flask and an acid etching is performed by means of a concentrated H CI, diluted 1 :1 with distilled water (about 18% concentration). To put the flask at 120° C on to a heating plate provided with magnetic mixer for 4 hours. To let it to cool and then to filter the solution in a matrass of 200 cc. To wash the filter and to dilute the solution up to 200 cc. To insert the capillary and to start the reading with a spectrometer instrument of the type ICP plasma, and to represent graphically the calibration curve of the interested element (Al).

DETERMINATION OF THE CONTENT OF THE METALLIC ALUMINIUM ONLY INTO THE MIXTURE OF THE RECOVERED PLASTICS

Specimen analysis :

The mixed and dried specimen must be additionally sectionalised by the operator with the aim to obtain a final specimen representative of the total. A subdivision in quarts of the specimen is then executed and, thereafter, the selected part is additionally reduced by a suitable rotating separator. To draw about 20 grams of the specimen, by introducing it inside a flask and to perform an etching with a solution (of about 100 cc.) of concentrated mineral acids (H CI. or HNO3) and distilled water with a 1 : 1 ratio.

To put the flask at about 120° C on to a heating plate provided with magnetic mixer for 4 hours. To let it to cool and then to filter the solution into a matrass of 200 cc. To wash more times the filter and to dilute the solution up to 200 cc.

To insert the capillary and to start the reading with a spectrometer instrument of the type ICP plasma, and to represent graphically the calibration curve of the interested element (Al).

If the specimen has a percentage of Al lower than 1% by weight of the total weight of the utilized material of cement, the lot of material can be utilized, in the contrary case the lot must be submitted to the following industrial process, described into the Fig.3.

PROCESS FOR ELIMINATING THE ALUMINIUM PARTICLES IN THE METALLIC STATE MIXED WITH RECYCLED PLASTIC FLAKES, TO BE HYGIENIZED, COMING FROM THE

SALVAGE DUMP

The effected treatment is based upon the chemical reaction which takes place between a solution of caustic soda and the pieces of aluminium (which notoriously is an amphoteric element) which are mixed with the plastic pieces deriving from the of recycle. For preventing the corrosion of the apparatus by the chemical reagents, all the receptacles, the hoppers, the reactors, the valves, the machines, etc., is recommended that are made realized with appropriate stainless steels (of the AISI 304 type or superior) and anti-corrosive materials.

During the reaction between the aluminium and the caustic soda, in addition to the forming of sodium aluminate, the hydrogen in the gaseous form is formed. This gas is particularly reactive and with the presence of oxygen may originate some fast combustions and, with certain mixing ratios, also the explosions. For eliminating such risks, the plants must be realized according to specific standards for the apparatuses designed for being utilized into areas with explosion risks (ATEX, Directive 97/9/CE of the European Union). Moreover, the apparatuses into which the hydrogen may be produced are regularly made inert (the oxygen is eliminated from their interior, by loading them with nitrogen, which is a nonflammable inert gas).

The by-product obtained during the manufacturing is the sodium aluminate. This salt is widely applied for different industrial fields: as coagulating - alkalinizing product for the water depuration treatment, for the paper industry, as setting accelerating additive for the articles manufactured with cement, as filler for manufacturing of fire-retardant panels and as a source of aluminium hydrate for other industries. For this reason, it is not correct to consider it as a waste product or by-product, since it is an actual raw material which takes place in different markets.

DESCRIPTION OF THE PRODUCED CHEMICAL REACTIONS

The process of dissolution of the aluminium particles is based upon the following chemical reaction:

2 Na OH + 2 Al. + 2 H2 O ► 2 Na Al. 02 + 3 H2, wherein 2 molecules of caustic soda + 2 molecules of aluminium + 2 molecules of water react by forming 2 molecules of sodium aluminate and 3 molecules of hydrogen. It is to be noted that the water used for the solubilization of the caustic soda is a part of the chemical reaction, in that the function to provide the oxygen molecules needed for forming the aluminate is attributed thereto. It is also possible to note that the process involves a large production of hydrogen.

DESCRIPTION OF THE MANUFACTURING PROCESS RAW MATERIALS

The raw material to be treated :

1. The raw material to be treated for eliminating the included metallic aluminium to be submitted to a sanitary treatment against possible bacteria, arrives to the plant packed into bales and is stocked indoor (see Fig. 3, in which the stocking area is indicated with 4). It deals with a material which has been already submitted to a first grinding treatment and the sizes of the single pieces are about 0,5 - 1 cm2.

2 - Caustic soda

For the manufacturing, it is used the technical product in the form of pearls (or drops) with a purity about of 98%. Since this product is extremely hygroscopic and deliquescent, it cannot stay freely into contact with the air.

For this reason, the material is purchased and delivered into sealed containers and introduced into the metering hopper 5 (hopper container made of stainless steel and hermetically closed and provided with a metering Archimedean screw) when it is needed only.

3 - Nitrogen

Since the nitrogen is an odourless, colourless and non-flammable gas, the same is used for the industry for making inert the silos and the reactors. For practicality, it is stocked into bottles, which can be easily recognized by the characteristic colours: according to the standard EN 1084-3, the bottles containing nitrogen are painted with grey (RAL 7031), while the ogives are painted with black (RAL 9005). In the Figure 3, the nitrogen bottle is marked with 6.

Since the bottles are under pressure, the nitrogen is admitted therein easily, by opening an appropriate tap, and the metering thereof is effected by a simple litres meter. The gas is admitted into the reactor interior before the basic solution is admitted therein, in such a way as to eliminate the existing oxygen before the hydrogen is produced and to prevent in this manner that some combustible or explosive mixtures be formed.

4 - Water

The waters used in the process are directly coming from the water supply system and they are subsequently recycled (indicated with 7) and the additions thereof are effected when needed only.

PROCESS DESCRIPTION

The metering of the plastic material to be separated from the aluminium and to be submitted to sanitary treatment against possible bacteria occurs by means of a large hopper 4 made of stainless steel loaded by a suitable hoister. At the top of the hopper 4 a vibrating grating for allowing loading thereof is situated, by preventing the casual introduction of improper parts or parts with large dimensions therein. At the base of the hopper a metering Archimedean screw supplying a hopper- balance 8 is situated, having inner sizes similar to the reactor's sizes, which is positioned on to loading cells controlled by microprocessor. When the weight of material pre-set in the

microprocessor is attained, said Archimedean screw is stopped and remains in stand by condition up to the subsequent operation. The weighed material is discharged by gravity and introduced into the reaction vessel 9.

The reaction vessel 9 is constituted by a container made of steel which cannot be etched by the alkali. In the interior thereof a perforated drum is positioned, able to rotate and to centrifuge the treated material. At the exterior of the vessel 9 a copper coil is situated, into which it is possible to circulate water at the desired temperature and to attain a temperature control.

When the introduction of the raw material to be treated in the interior of said reaction vessel 9 is terminated, the loading mouth thereof is sealing closed and the valve 10 venting on the

atmosphere is opened, then from the bottom of the reservoir 6 the gaseous nitrogen is introduced, in such quantity as to ensure the total elimination of the oxygen initially contained in the interior of the reactor 9, directly in the atmospheric air (for ensuring that the oxygen is completely ejected, a quantity of volume of nitrogen which is the double than the volume of the reactor vessel 9 is admitted). When the oxygen ejection is terminated, it is started the introduction of the aqueous solution of caustic soda, which was diluted in advance at 20% by weight.

The pearl soda is weighed into the hopper 5 and then introduced into a proper reservoir 11 and thereafter diluted with a metered water quantity when used ; since this is an exothermic reaction, namely developing heat, this heat is used for increasing the reaction speed during the chemical etching of the metallic aluminium.

By letting water to flow through the coil near the jacket of the reactor 9, it is possible to increase the temperature in the interior thereof and therefore to speed up the chemical reactions.

Since, as already explained, the reaction is strongly exothermic, and that this is still started, it will be not necessary to heat the reactor 9.

Up from the first contact between the caustic soda and the aluminium molecules, the chemical etching and the consequently generation of hydrogen starts, which latter must be absolutely evacuated from the reactor 9 and dispersed in the atmosphere through the valve 10 ( on the basis of the quantities of plastics which have been treated, it is possible also to collect the hydrogen by pumping it into the bottles with appropriate machines).

The reactor 9 is provided internally with a metallic impeller which, by rotating slowly, facilitates the contact between the aluminium and the basic solution. This operation must be prolonged up to the production of hydrogen occurs (which indicates that the metallic aluminium is still present). At the end of the chemical reaction:

- the reactor 9 is made inert again by ejecting the hydrogen through introduction of nitrogen.

- the reactor 9 is emptied from the liquids, the liquid solution is at first filtered through filters 12, for stopping any possible plastic particles and then discharged into a suitable receptacle 13 and let to cool, with the consequent precipitation of the crystals of sodium aluminate, which will be separated by means of filtering with filters 14 and adequately stocked into a container 15, while the remained solution after the filtering is conveyed to the recycle 16 and stocked, ready for being re-used, after any possible topping up, in a new productive cycle.

- The treated material is submitted to a high speed centrifugation into the reaction vessel 9, during which the reactor 9 is emptied from the separated liquid 12. The treated material is transferred by means of suction and introduced into a proper drying oven 17 ventilated with hot air, in order that the remained water particles be eliminated by evaporation.

- The treated material is now ready for being packaged and stocked.

NOTES:

The centrifugation and the subsequently drying don't allow to eliminate totally the formed sodium aluminate and the admitted caustic soda which, at least in small particles, will remain trapped onto the surface of the plastic; however, this fact doesn't constitute a problem in that:

1- the metallic aluminium has been totally eliminated and the material is not more able to produce hydrogen and therefore to produce the damaging "bubbles" or fractures inside the article manufactured with cement.

2- The sodium aluminate and the caustic soda into a mortar of cement perform an accelerating setting action and allow, also during the cool season, to achieve in short times the values of mechanical strength which are sufficient to allow the pedestrian traffic on to the articles in short times.

3 - The sodium aluminate into a mortar of cement is transformed in the calcium aluminate and by exploiting a binding action increases the final mechanical strengths thereof.

For the above-mentioned reasons, it is not necessary to clean strongly the material by means of additional washing. In the case only in which it's desired to obtain a material without these "impurities", before the emptying of the reactor 9 it will be necessary to perform an additional washing with clean water and a further centrifugation.

After the drying, the treated material is introduced into a sealed stocking hopper 18, before to package it in the specific area 19.

The finished product must be absolutely stocked into a room 20 protected from the rain and the humidity in general.

DOSAGE OF THE REACTING PRODUCTS AND CHEMICAL BALANCING

By means of innumerable checking tests, it has been verified that the content of metallic aluminium into the raw material to be treated is variable up to 1 % by weight, with rare peaks which may reach the 1,4%. Starting from these data, it has been established the quantity of the reagent (caustic soda) to be used.

With the stoichiometric calculation, it is obtained that for each Kg. of metallic aluminium (Al) to be chemically etched, there are needed 1,48 Kg. of caustic soda (Na OH).

By using a solution of caustic soda at 20%, in quantity sufficient that it comes into contact with all the material, one will be unavoidably to work with a very excessive solution, however this fact will allow to attain certainly the total dissolution of the metallic aluminium within quick times.

Therefore, if for simplicity it is supposed to treat 100 Kg of plastic material polluted by about the 1,4% of metallic aluminium, by means of a simple equation it is possible to establish the consumption of caustic soda:

1 : 1,48 = 1,4 : x and then x = 1,48 * 1,4 x = 2,072

For each 100 Kg of plastic it will obtained a maximum consumption of about 2,072 Kg of pure caustic soda.

By working with an aqueous solution concentrated at 20% it will be obtained :

20 : 2,072 = 100 : x and then x = 2,0072 * 100 / 20 x = 10,36

By using a solution of caustic soda at 20% by weight, to etch chemically the metallic aluminium contained in 100 Kg of plastic material ( max 1,4 Kg of aluminium), it will be necessary, at the maximum, 10,36 Kg of solution (at 20% by weight).

As it has been previously noted, in order that the reaction between the caustic soda and the aluminium may take place, it is necessary the presence of water.

2NaOH + 2A1 + 2H20—► 2NaA10i + 3H2

The molecule of water, in fact, must resolve itself and cedes its oxygen atom, in order to be able to form the aluminic acid. The two molecules of hydrogen, no longer chemical bound to the oxygen, at this point release themselves under the form of H2.

During this chemical reaction, therefore, there is obtained a water consumption : through a stoichiometric calculation it has been verified that for each Kg of aluminium etched by the caustic soda, it will be necessary 0,0670 Kg of water, which will be decomposed during the reaction.

Theoretically, it should be taken into account this quantity of water during the operations of dilution of the soda ; however, since the quantities are very low, this quantity is non influent.

For checking the concentration of the solution of caustic soda coming from the recycling, it will be sufficient the use of an appropriate instrument to be immersed therein : since depending on the concentration also the specific weight of the solution changes, the instrument will float in different manners with the different degrees of concentration. Therefore, the concentration value will be read directly on the graduated scale depending on the floating condition.

Claims

1. Process for manufacturing a composition of cement made of waste or virgin materials of various kind, adapted to be used with the function of material having good thermal conductivity, particularly in the building industry, as self-levelling screed for covering the heating panels to be applied on to the floors of traditional type, by using waste or virgin materials of common use, in a way to obtain a better and more effective heating of the inhabited rooms, the composition of cement being substantially constituted by the following component materials :

a) waste materials of various kind, ground in advance to have small-sized particles, and particularly wastes of plastic materials (ex. bottles of coloured, blue, transparent PET, small bottles, neolith, aggregates etc...) of heterogeneous type, wastes of elastomeric materials (rubbers, etc.), wastes of paper, cardboard, packages of various kind and with compositions of different materials (ex.

aluminium and plastic etc.), and cellulosic-based materials and/or materials with polymeric basic compositions (poly-coupled materials etc.), solid urban wastes, wastes of woods and woody materials of various kind, inert materials of various kind for building industry, glass remainders of various kind, said materials being adapted to be used alone or combined to each other with different combinations and combinations at will of two or more materials of this kind, said materials being utilized without metallic materials or with extremely reduced percentages of the same metallic materials ;

b) cement and particularly cement 32, 5 Portland or 42, 5 Portland ;

c) half-dried fine sand aggregate ;

d) water ;

e) fluidizing or super-fluidizing additives ;

f) filler ;

g) ash ;

the composition of cement being obtained by mixing to each other at first the components of the point under a) with different and variable percentages thereof, and then by grounding in advance such components for obtaining small-sized particles of the same components, which are subsequently introduced into concrete mixers and vehicles of other kind, from which they are then delivered on to the sites of application, characterized in that, in the case in which said waste materials include aluminium, it is effected a sampling of the same by drawing at least a specimen to be analysed therefrom, so as to check the percentage of aluminium contained into these materials and, if such percentage of aluminium exceeds 1% by weight of the total weight of the material ofcement to be utilized, said waste materials are submitted to a de-aluminizing treatment before being utilized, by employing the nitrogen and sodium hydrate, and on the contrary if such percentage is lesser than 1% by weight, said waste materials are utilized without the de-aluminizing treatment, and characterized in that said component materials of the points under a), b), c), d), e), f) of the utilized composition of cement are mixed to each other with the following proportions :

a) waste materials of various kind : about 30 +/- 10 Kg./m3 ;

b) cement type 32, 5 Portland or 42,5 Portland : about 400 +/- 50 Kg./m3 ;

e) super-fluidizing additives : from 0,5 to 1% by weight relative to the cement ;

f) filler : from 50 to 150 Kg./m3 depending on the nature of sand aggregates, if sand aggregates have very fine grains the filler may be omitted ;

f) ash or mineral addition : up to 70 Kg./m3 depending on the nature of the sand aggregates.

g) super-fluidizing additives : from 0,5 to 1% weight relative to the cement.

2. Process according to claim I, characterized in that said waste or virgin materials being used for obtaining self-levelling screeds are obtained with different shapes of the fibers or the granules of waste or virgin materials of the point under a), which always assume an irregular shape, of scaled kind, however having dimensions of 1-2 cm. only and substantially bi-dimensional, in a manner that the shape of these fibers or granules mixed with the material of cement does not hamper the flow and the flowability of the material poured into place and allows the same to be used with large quantities (from 20 to 60 Kg./m3), thereby creating a super-fibrous self-levelling screed having a strong isotropous behaviour, without producing crazes or cracks, and without utilizing electric welded or galvanized nets to be applied on to the heating radiating panels put on to the floor.

3. Process according to claim 2, characterized in that said sampling is effected with the following test method, by taking into account that the specimen to be analysed should be representative and therefore should be drawn from many parts of the total quantity of the material of the composition of cement :

- from 1000 Kg. of material, there must be effected at least 10 drawings with a ladle, each one of which having about 100 gr. ;

- reduction of the drawn specimen by means of subdivision into quarters, in accordance to the Standard UNI EN 932-2 paragraph 10, by putting the lab specimen on to the working surface, by mixing accurately the specimen with the ladle and heaping it to form a cone and turning it upside - down so as to form another cone, and by repeating three times this operation and, when the cones are formed, by putting each filled up ladle on to the top of the new cone, in such a manner that the aggregate (the product) goes down from all the sides of the cone and be uniformly distributed and the various granules are adequately mixed to each other ;

- flattening of the third cone which has been obtained, by beating the ladle with a vertical movement more times on to the top of the cone, up to form a flat heap having uniform diameter and thickness ;

- subdivision into quarters of the flattened heap along the diagonals intersecting at right angle to each other ;

- discarding of a pair of opposed quarters and assembling the remainder with the ladle in a heap ;

- repeating the mixing and the subdivision into quarters up to the requested test portion is obtained ; - preparing the specimen to be analysed, by drying at 60° C the material obtained by means of the subdivision into quarters, for at least two hours and up to the specimen, between two weighings, has lost less than 0,2 % by weight ;

- recording and registering the obtained results.

4. Process according to claim 3, characterized in that for effecting the specimen analysis, the specimen must be additionally sectionalised by the operator, and therefore a subdivision into quarters of the same specimen must be performed, and, thereafter, the selected part thereof is further reduced by means of a proper separating rotating machine ;

and characterized in that the total content of aluminium of said waste materials must be analysed :

- by drawing from the specimen about 25 gr. and putting them into a porcelain bowl and, by means of a Bunsen burner, by burning the plastic material, by looking for avoiding that a flame be developed, so as to get a loss of weight of about 65 % ;

- by putting, at the end of this first calcining, the obtained ashes into a muffle at the temperature of 480° C for 4 hours, so as to achieve after this second thermal treatment a loss of weight of about 89%, under the condition in which the organic and/or synthetic materials have been eliminated in a large part by combustion and the obtained aluminium has oxidized to form A12 03 ;

- by transferring the obtained ashes into a flask and performing an acid etching by means of a concentrated H CI., diluted 1 :1 with distilled water (about 18% concentration) ;

- by putting the flask at 120° C on to a heating plate provided with magnetic mixer for 4 hours, and letting it to cool and then by filtering the solution in a matrass of 200 cc. ;

- by washing the filter and diluting the solution up to 200 cc. ;

- by inserting the capillary and starting the reading with a spectrometer instrument of the type ICP plasma, and representing graphically the calibration curve of the interested element (Al.).

5. Process according to claim 4, characterized in that the content of the metallic aluminium alone into said waste materials is analysed :

- by drawing about 20 gr. of the specimen, by introducing it inside a flask and performing an etching with a solution (of about 100 cc.) of concentrated mineral acids (H CI. or HN03) and distilled water with a 1 : 1 ratio ;

- by putting the flask at about 120° C on to a heating plate provided with magnetic mixer for 4 hours ;

- by letting it to cool and then by filtering the solution into a matrass of 200 cc. ;

- by washing more times the filter and by diluting the solution up to 200 cc. ;

- by inserting the capillary and starting the reading with a spectrometer instrument of the type ICP plasma, and representing graphically the calibration curve of the interested element (Al.), under the condition in which if the specimen has a percentage of Al. lower than 1% by weight of the total weight of the utilized material of cement, the lot of material can be utilized, in the contrary case the lot must be submitted to said de-alummizing treatment.

6. Process according to claim 1, characterized in that said de-aluminizing treatment is based upon the following chemical reaction, which takes place between a solution of caustic soda and the pieces of aluminium (which notoriously is an amphoteric element), which are mixed to the plastic pieces deriving from the recycle :

2 Na OH + 2 Al. + 2 H2 O ► 2 Na Al. 02 + 3 H2, wherein 2 molecules of caustic soda + 2 mulecules of aluminium + 2 molecules of water react by forming 2 molecules of sodium aluminate and 3 molecules of hydrogen ;

- the metering of the plastic material to be separated from the aluminium and to be submitted to sanitary treatment occurs by means of a large hopper (4) made of stainless steel, loaded with a hoister means, to the top of which a vibrating grating for allowing loading thereof is situated, by preventing the casual introduction of improper parts or parts with large dimensions therein, and at the base of which a metering Archimedean screw is situated, supplying a hopper-balance (8) positioned on to loading cells controlled by microprocessor, and under this condition when the weight of material pre-set in the microprocessor is attained, said Archimedean screw is stopped and remains in stand by condition up to the subsequent operation ;

- the weighed material being discharged by gravity and introduced into a reaction vessel (9), constituted by a container made of steel which cannot be etched by the alkali, in the interior of which is positioned a perforated drum, able to rotate and to centrifuge the treated material, and on the exterior of which is situated a copper coil, into which it is possible to circulate water at the desired temperature and to attain a temperature control ;

- when the introduction of the raw material to be treated in the interior of said reaction vessel (9) is terminated, the loading mouth thereof being sealingly closed and the valve (10) venting on the atmosphere being opened, then from the bottom of a reservoir (6) for the gaseous nitrogen being introduced the gaseous nitrogen into said reaction vessel (9), in such quantity as to ensure that the oxygen initially contained in the interior of the reactor be totally eliminated directly in the atmospheric air ;

- at the end of the oxygen ejection, into said reaction vessel (9) being introduced an aqueous solution of caustic soda, which was diluted in advance at 20% by weight, said pearl soda being weighed into said hopper (5) and then introduced into a proper reservoir (1 1) and thereafter diluted with a metered water quantity when used ; since this is an exothermic reaction, namely developing heat, this heat is used for increasing the reaction speed during the chemical etching of the metallic aluminium, under the condition in which by letting water to flow through the coil near the jacket of the reactor (9), it is possible to increase the temperature in the interior thereof and therefore to speed up the chemical reactions ;

- the hydrogen developed from the chemical reaction between said caustic soda and the aluminium being discharged from the reactor (9) and dispersed in the atmosphere through said valve (10), the contact between the basic solution and the aluminium being helped by a metallic slow rotating impeller provided into said reactor (9), and this operation being effected until the hydrogen is generated (this means that the metallic aluminium is always present) ; - when the chemical reaction is terminated, said reactor (9) being made inert again by ejecting the hydrogen through introduction of nitrogen, and being also emptied from the liquids, under the condition in which the liquid solution is at first filtered through filters (12), for stopping any possible plastic particles, and then discharged into a suitable receptacle (13) and let to cool, with the consequent precipitation of the crystals of sodium aluminate, which will be separated by means of filtering with filters (14) and adequately stocked into a container (15), while the remained solution after the filtering is conveyed to the recycle (16) and stocked, ready for being re-used, after any possible topping up, in a new productive cycle ;

- the treated material being submitted to a high speed centrifugation into said reaction vessel (9), during which the reactor (9) is emptied from the separated liquid (12), and the treated material being transferred by means of suction and introduced into a proper drying oven (17) ventilated with hot air, in order that the remained air particles be eliminated by evaporation, with subsequent stocking of the treated material in a sealed stocking hopper (18), before to package it in the specific area (19), and the finished product being then stocked in a room (20) protected from the rain and the humidity in general.

7. Process according to claim 6, characterized in that for each Kg. of metallic aluminium (Al.) to be chemically etched there are needed 1,48 Kg. of caustic soda (Na OH).

8. Composition of cement obtained with the process according to claims 1-7, characterized in that to be constituted by the component materials of the points under a), b), c), d), e), f), g) mixed to each other with the proportions described into the claim 1.