CN1094911C - Process for the cold conversion of municipal waste and/or sludge into inert substances, plant for carrying out the process and products obtained therefrom - Google Patents

Abstract

The invention relates to a method for cold conversion of municipal solid waste (USR) and/or sludge into inert material, comprising the following steps: feeding USR and/or sludge from respective feed lines; introducing the material into a pulverizer to reduce particle size and recover water contained therein; adding CaO in an amount of 5 to 10 weight percent based on the main component; adding 5-10 wt% of CaCO as main component₃(ii) a Adding polymer additive with 3-10% of main component; the product is conveyed to the forming and storage step. The invention also relates to a device for implementing the method and the product obtained by the device.

Description

Process for the cold conversion of municipal waste and/or sludge into inert substances, plant for carrying out the process and products obtained therefrom

The invention relates to a method for the cold conversion of municipal waste and/or sludge into inert substances, as well as a device for carrying out the method and the products obtained therefrom.

Litter is well known to have a significant impact on the environment, even though efforts have been made to minimize the aforementioned environmental ecological imbalances through often costly and inadequate cultivation techniques.

Waterproofing does not in any case ensure an ideal seal, causing leakage and diffusion of anaerobic fermentation products and toxic products in the deep layer to form initial waste.

Despite the attention given by those skilled in the art, these issues have not been resolved, especially in terms of prediction and prevention (environmental degradation, atmospheric and water pollution, airborne microorganisms, rodents, etc.) ) is even more so, and currently particularly relates to people's requirements for rubbish to be far away from its living quarters, factories, parks, etc., that is, to be far away from all places related to people's lives.

Of note are the high costs and user fees associated with such facilities. Full consideration should be given to land purchase, related engineering, personnel and machine management.

Furthermore, for road users, the problem of transporting USR from the collection point to the conversion station and then to the final dump cannot be ignored (approximately 100,000 transport vehicles per day).

If you consider the amount of USR generated in Italy on a daily basis, the amount is extremely huge.

In fact, assuming 0.94 kg/day per capita, considering a population of 50,000,000, an average daily production of 47,000 t/day corresponds to a compact volume of approximately 770,000 m ³ /day of waste.

Considering the dense waste material with an average thickness of about 5 meters, it is expected to occupy about 150,000 square meters of ground every day, and the presumed restoration of the area will take ten years.

Currently, an alternative to the above treatment is incineration. When incineration is associated with heat recovery, it is called a "thermal incinerator".

It can be denied that in the presence of plastic substances, there is a large amount of carbon dioxide, which consumes a large amount of oxygen and produces dioxins, resulting in an imbalance in the ecological system under the influence of the environment.

Furthermore, the combustion of sludge and municipal solid waste is known to generate large amounts of sulfur dioxide, leading to increased acid rain, whereby the discharge problem is in any case significant and difficult to deal with, and the ash deposit also requires suitable slag yards.

The solution of the invention is based on the concept of converting waste into "primary-secondary" materials.

"Primary": suitable material for the implementation of new processes due to its recovery enabling its use in new production cycles.

"Secondary": Since it is not produced in a cycle suitable to prepare it to be placed on the market, but as waste, it means that it constitutes some kind of waste to be disposed of.

Municipal solid waste (USR) consists of specific salable items whose percentages can vary within small limits.

The above-mentioned types of salable items are also influenced by public habits.

On average, the USR includes the following categories: 1) Dust and fine inerts - 13%; 2) Organics - 27%; 3) Wood and vegetation - 3.5%; 4) Paper and cardboard - 25%; 5) Plastics - 10.5% 6) Glass and heavy inerts - 5%; 7) Fabrics - 4.5%; 8) Iron materials - 2.5%; 9) Washing machines, furniture, box springs, etc. - 1%; 10) Diapers and napkins - 3% %; 11) Various unclassified items - 5%.

As we all know, the concept of recycling does not establish any other solution, but only the selection and separate reuse of the following items: glass, paper, certain heavy metals (iron, aluminium), and certain types that represent Plastic articles that do not have a good economic interest due to the cost and value of the resulting product.

Plastic can only be sent to make low-value products, glass should be sorted according to color, paper needs high recycling costs, etc.

Even though domestic sludges are of lower quality compared to USR, their environmental pollution problems and high water content (70/80%) and consequent high transport costs must not be underestimated.

The technique of composting with other organic matter makes it possible to obtain so-called high-quality compost.

The low demand for composting and market concerns also make this solution very problematic and indeed unsuitable as a routine solution.

The first solution of this kind has been proposed in Italian patent application N°RM 91A000242, filed on April 9, 1991 and granted on July 15, 1994 with patent number 1,244,506.

Improvements to this method are envisaged here to obtain a more optimal end result.

The improvement of the transformation method envisaged according to the present invention enables the use of inert substances, making it widely applicable and even more attractive as an undisputed "removal method".

The technology conceived according to the invention differs from it in terms of workmanship, even if it is inspired by the technology of the 70s for the treatment of radioactive and toxic waste. The process uses polymeric additives instead of mixtures of alumino-silicate compositions which, even with good inertization characteristics, do not possess and do not guarantee the physical and mechanical properties obtained by the solution of the invention.

Another feature of the present technology is the introduction of a polymer additive that modifies certain aspects of the interaction between the waste material and the concrete binder.

The solution proposed by the invention is economical both in terms of investment and energy utilization, and also has remarkable environmental adaptability.

All of the above marketable items are fully consistent with concrete once inertized by polymer additives and specific catalysts.

After the concrete is treated by the method of the invention, the sludge is completely consistent with the concrete.

The solution according to the invention makes use of the adaptability between the inert products obtained from the conversion of USR and/or sludge and concrete within the limits defined by physico-chemical rationality.

In fact, the inertization material allows the mixing of the same properly comminuted material in different particle sizes in the concrete binder, facilitating the adaptation process of the polymer additive and its catalyst.

The above makes it possible to distinguish the process of admixing the obtained inert product with concrete in proportion to the other materials, thus confirming the excellent technical and mechanical effect of the product.

In particular, the realized advantages can be respectively reflected in specific gravity, porosity, air permeability, solidification, thermal conductivity, fire resistance, hardness, compression resistance and processability.

The product obtained according to the invention makes it possible to treat the waste not as a substance to be removed in concrete, but as a typical component of cement.

The process of the invention is always carried out under cold conditions, except for the heating step (temperature at 50/60° C.), in order to obtain efficient operation and conversion of USR and/or sludge. The recovered steam is obtained via a suitable heating system (resistance heating) and the USR and/or sludge are dried and pulverized in the final product production step, ie where the granule drying step takes place (temperature always 50/60°C). The above-mentioned granules are ready to be placed on the market as inert substances.

Studies have shown that the separation and recycling of USR components of many salable items is inconvenient in view of the high energy consumption and lack of return from the sale of said products.

Consequently, the recoverable fraction, which accounts for 45% of the plant, cannot be easily recovered by known solutions.

In fact, many plants implementing separation methods are unable to remove the recovered products, which remain in the plants and are not sold, given the high regeneration costs of these materials for their reuse.

Due to the micro plastics, glass and heavy metals contained in compound fertilizers, agricultural personnel do not want to deal with the ground, and the compound fertilizers currently obtained cannot be used as chemical fertilizers.

This is why recyclables that cannot be placed on the market are charged and sent back to the dump, with corresponding additional costs.

The only component contained in the extract of the fraction of material with the highest calorific value that can be utilized by energy recovery from waste is RDF (Fuel from Waste), which is used in thermal power plants, cement plants, etc. as an alternative combustion agent.

Based on the above considerations, it is provided in the method of the present invention that comminution of all these substances (including the types of salable items including USR) is carried out, both on the dry component and on the wet component, and on the section operator. It is economically justifiable to comminute the dry fraction, i.e. the recyclable fraction.

Thus, according to the invention, it is possible to implement, according to specific requirements:

a) USR transformation methods by recovering the recoverable fraction;

b) USR conversion method without recovery of recoverable fraction.

For case (a), in addition to a water centrifuge with filter to reuse the separated excess water, the method also requires the use of separation machinery capable of recovering recyclables (glass, paper, wood, heavy metals, etc.).

For case (b), the method does not require the above-mentioned machinery, thereby significantly reducing the cost of machinery and power consumption.

Furthermore, observing the transformation phase of the individual particles in the laboratory, it has been noted that particles with low permeability and highly dehydrated are obtained.

It has been further confirmed that the high concentration of "hydroxyl groups" facilitates the concrete hydration process when the concrete aggregates are combined and mixed with water, thus making the product highly permeable after the chemical phenomenon.

Furthermore, the product obtained by the method of the invention ensures that no pathogenic microorganisms or bacteria of any kind can survive due to the well known very high pH of concrete between 11 and 12.

Moreover, since the transport phenomenon of polar molecules occurs only under two possible conditions: through the "potential gradient" or through the "concentration gradient", the transport phenomenon does not occur because the resulting elements are limited by the height of the solid structure of the concrete; so Heavy metals that exist in the form of corresponding hydroxides in the concrete structure are immobilized.

It is therefore a particular object of the present invention to provide a method for the cold conversion of municipal solid waste (USR) and/or sludge into inert substances, the method comprising the steps of:

- feeding USR and/or sludge from the corresponding feeding lines;

- introducing the material into the pulverizer to reduce the particle size and recover the water contained in it;

- adding 5-10% by weight of CaO to the main component;

- adding CaCO ₃ of 5-10% by weight of the main component;

- adding polymer additives of 3-10% by weight of the main component;

- Conveying the product to the forming and storage steps.

According to the invention, a further 20-50% by weight of a suitable catalyst is preferably added.

Also, according to the invention, said polymer additive is selected from polyvinyl acetate and its derivatives, polyurethane and its derivatives, and styrene polymers and their derivatives.

Furthermore, according to the invention, said polymer additive can be applied in the form of a "suspension" or "solution" to the product obtained from the USR and/or sludge to be converted. The "suspension" treatment occurs when USR and/or sludge particles are inertized with polymer additives, effectively "smearing", thereby imparting low permeability and low penetration in the microporous structure to the converted particles. Permeability, which is limited by micro-coatings (membranes); while "solution" processing can confine macromolecules and thus all their molecular properties to micro-porosity and macro-porosity, obtaining relative to using "suspension" polymer additive Really effective effects (thermal insulation, permeability, adhesion, etc.) for simple membranes obtained.

Still according to the invention, along the USR feed line there are provided a deironing plant with a mechanical compressor for the waste, a main rough breaker, in particular with four coring hammers.

In addition, a rotary iron removal device with collecting combs and rotating sleeves, a coarse material recovery system and a second crusher may be provided downstream of said primary crusher and upstream of said pulverizer.

Furthermore, according to the invention, a water recovery tank may be provided downstream of the masher.

Still according to the invention, said product forming line may provide a granulation line provided with a dehumidifier group and/or a product line provided with a formwork vibrating table.

Another specific object of the present invention is to provide a device for implementing the above method, the device comprising:

- at least one, preferably two concrete tanks to discharge USR (Urban Solid Waste) and sludge respectively;

- at least one, preferably two, mobile overhead cranes equipped with forks for loading a conveyor belt provided with suitable tanks;

- a first horizontal conveyor belt with feeding tanks for feeding the masher;

- iron removal plant with waste mechanical compressor located above the first conveyor belt mentioned above;

- Coarse primary masher with cutting hammer;

- a second horizontal conveyor belt with a feeding tank feeding the rear sieve;

- Iron removal equipment equipped with combs for collecting fine materials;

- hexagonal rotary sieve;

- a third horizontal conveyor belt located below the rotary screen, which collects the screened material and sends it to the mixer feed conveyor;

- second cutting hammer masher;

- a fourth inclined conveyor belt suitable for taking the unscreened material to the second crushing process, provided with sides along all its length, equipped with a feeding tank, a discharge box and an electric motor with a reduction gear;

- a fifth horizontal conveyor belt suitable for conveying crushed material to the rotary screen conveyor belt;

- pulverizer-heater with water recovery;

- a sixth inclined conveyor belt suitable for conveying crushed products to the feeding and discharging buckets;

- CaO (quicklime) tanks;

- CaCO ₃ (calcium carbonate) storage tanks;

- storage tanks for polymer additives;

- Ultimately a specific catalyst tank;

- three more conveyor belts, two of which are horizontal and one inclined, the inclined conveyor belt is located under the bucket collection trough, which sends the screened material to the mixer in an alternating manner;

- Paddle sealed mixer with supports, channels, safety guardrails, round section discharge hopper, observation hole, engine and reduction gear, inlet material weighing system and additive atomization system;

- a tenth horizontal conveyor belt suitable for conveying the screened material to the extruder;

- An eleventh horizontal conveyor belt suitable for conveying screened material to the product line.

The invention further includes products obtained by the process of the invention.

The invention is now described by illustrative but non-limiting preferred embodiments with specific reference to the accompanying drawings, in which:

Fig. 1 is a block diagram of an apparatus according to the invention.

Figures 2a, 2b and 2c are schematic views of an industrial plant according to the invention.

Referring to Fig. 1 first, the block diagram of the device of the present invention can be seen, which is provided with an inlet comb B for intercepting a large amount of materials, a USR bucket B or a discharge ditch, a sludge bucket C or a discharge ditch, and a mobile elevated shelf for collecting a hopper of USR Crane D and mobile overhead crane E with a hopper for sludge collection.

In addition, there are a series of conveyor belts or screw feeders F for the product processing process, a series of iron removal equipment G suitable for removing all ferromagnetic substances together with other iron removal equipment, a coarse main crusher H, processed in the following A rotary screen I for waste materials, a second grinder L suitable for finely pulverizing the salable components of waste materials and a pulverizer-heater M for collecting water vapor are selected in the steps.

In addition, 4 tanks N containing products for the conversion of USR and/or sludge, to be precise products available for the conversion process, namely CaO (limestone), CaCO ₃ (calcium carbonate) and additives can be noted.

As already mentioned, additives may include polyvinyl acetate and its derivatives, polyurethane and its derivatives, and styrene polymers and their derivatives; specific catalysts.

It is further provided with a feeding and discharging hopper O, a paddle mixer with nozzles for atomization of additives and an automatic dosing device), a pellet extruder Q, air and low temperature (50/60°C) dryer-dehumidifier R, which are interconnected by mechanical conveyor belts, manipulated and coordinated by a manual (or, if necessary, computerized) control system, a storage room S or a final product bag packaging system ready for placing the product on the market, a template T for obtaining the desired product , a vibrating plate U for compressing wet materials in the formwork, and a storage chamber V.

Considering that each plant must not overcome a production capacity between a minimum of 100 t per day and a maximum of 250 t per day of USR and/or sludge, such industrial plants can be dimensioned based on their capacity to receive the material to be converted.

Therefore, for plants with a manufacturing conversion higher than 250t/day, it is recommended to juxtapose the plants, keeping in mind that the production time to obtain the final product is always 8 hours.

Figures 2a, 2b and 2c are schematic views of an industrial plant according to the invention.

The various components of the device will be listed below, identified by reference numerals and explaining their functions.

1a) 1b): These are two concrete tanks, sized according to the capacity of the installation, for the discharge of USR (Urban Solid Waste) and sludge.

Concrete pools have a frusto-pyramidal shape that allows for easy emptying without unwanted material buildup in the corners. The concrete pool is further provided with handrails in compliance with current regulations.

2a) 2b): - be a mobile overhead crane of suitable size, provided with forks to load a conveyor belt with suitable tanks.

3): A horizontal conveyor belt with a feeding tank for feeding to the masher.

Said conveyor belt will house the engine, reduction gear, counter gear, discharge side case.

4): Iron removal equipment with waste mechanical compressor located above the above conveyor belt.

5): Coarse main crusher with cutting hammer, the hammer is equipped with four cores - equipped with electric motor and hydraulic transmission device. The masher has feed holes, comb adjuster, product discharge chute, side maintenance holes. The machine is placed on the supporting frame together with the conveyor belt 3, and is provided with an inspection channel and a safety handrail.

6): A horizontal conveyor belt with a feeding tank feeding to the sieve below.

Said conveyor belt is provided with motors, motoriduttore, counter gears, side discharge boxes, covering along its entire length, intermediate supports, plane carpet to drag the material.

7): Iron removal equipment equipped with a comb for collecting fine materials.

8): Hexagonal rotary sieve with external transmission, rubber wheel frame for support and rotation, sealing cover with observation manhole, tank for discharging sieved material under the rotary sieve, discharge tank for unscreened material , Feeding port, epicycloid reduction gear, maintenance channel, ladder, motor.

9): Horizontal conveyor belt located below the rotary screen, collects the screened material to send it to the mixer feeding belt. There are side walls along its entire length, a discharge box and a reduction gear motor.

10): A second cutting hammer masher with a drive motor with a hydraulic connection and a double comb for deep comminution. It has feed port, comb adjustment, product discharge chute, side port for maintenance. The machine is placed on the supporting frame together with the feeding belt 3, and is equipped with maintenance channels and safety handrails.

11): An inclined conveyor belt suitable for sending unscreened materials to the second crushing process, with side walls along its entire length, equipped with feeding tanks, discharge boxes and motors with reduction gears.

12): Inclined conveyor belt suitable for sending crushed materials to the rotary screen conveyor belt. There are side walls along its entire length, and there are feeding tanks, discharge boxes and motor boxes.

13): Grinder-heater with water recovery. The pulverizer 13 consists of a machine that breaks the material under static force through its mechanical action and produces a dynamic impact on the solid particles of the material, pushing the particles to a fixed plate (deck) or a moving plate (hammer). This creates a mashing action that reduces the particle size. At the same time, the electrical resistance heats and dries the material, thereby reducing the material flow rate and recovering moisture by evaporation, which can be reincorporated into the process, ie into the dehumidification step of the wet granules.

14): Inclined conveyor belt suitable for conveying crushed products to feeding and discharging buckets. It has side walls and is covered over its entire length with a discharge tank, a discharge box and a variable speed motor.

15): CaO (quicklime) storage tank.

16): CaCO ₃ (calcium carbonate) storage tank.

17): Polymer additive storage tank.

17'): specific catalyst tank.

18): Three conveyor belts, two of which are arranged horizontally and one inclined, the inclined conveyor belt is located under the bucket collection trough, and the sieved material is sent to the mixer in an alternate manner. The conveyor belt has side walls along its entire length, a discharge chute and an electric motor with reduction gear.

19) and 19') are equipped with paddle sealing mixers with supports, passages, safety guardrails, circular section discharge buckets, observation holes, engines and reduction gears, inlet material weighing systems and additive atomization systems.

20): Horizontal conveyor belt suitable for feeding screened material to the extruder, with side walls along its entire length, discharge box and electric motor with reduction gear.

21): Horizontal conveyor belt suitable for conveying screened material to product pipeline, with side walls along its entire length, discharge chute and motor with reduction gear.

22): Wooden or metal formwork with different geometric shapes, its function is to shape the wet product obtained after conversion into the formwork to obtain products (blocks, bricks, pavement bricks, etc.). Then remove the product after it has hardened.

23): Vibrating plates including pneumatic or electrohydraulic machinery, which cause vibrations of the mechanisms affected by them. Vibration action facilitates the compaction of the material inside the formwork after the wet material is poured into the formwork.

24): An extruder comprising an Archimedes screw or a piston, the material is thrown towards a holed grid, whereby granules of different sizes are obtained as inert material for construction.

25): Inclined conveyor belt suitable for conveying the mixed product to the dehumidification group. The conveyor belt is provided with side walls and covered along its entire length with feeding tanks, discharge boxes and electric motors with reduction gears.

26): wet granule dehumidification group, including two coaxial drums, in which warm air (50/60 ℃) is introduced into the outer drum through suitable small holes, and the material treated by the mixer is introduced into the drum with holes Internal drum. The dehumidification group is equipped with methane or gas oil warm air generator, with heat insulation channel, motor filter and motor box.

27): Horizontal conveyor belt suitable for sending transformed materials to storage areas. There are side walls along all its length, with feeding tank, discharge box and electric motor with reduction gear.

28): Operate all mechanical electrical installations, including: master brakes, schematic diagrams, masher and master brake ammeters and voltmeters, remote control switches, cables, motor mounts, motors with temporary systems (in case of emergency shutdown) Start and stop control, process computer control system.

Said transformation method can also be used only for domestic sludge, but also for sludge which can be recovered from deep in the river bed. In the depths of the river bed, the sludge sedimentation capacity increases due to the death of a large number of bacterial microorganisms due to lack of oxygen.

The technology proposed according to the invention also enables the conversion of sludge only, so that by using suitable integrated machinery on board barges it is possible to simultaneously dredge the depths of the river bed and convert the sludge into inert substances.

The operation of the plant is described below in which only sludge conversion is carried out.

Said device can be mounted, for example, on a barge provided with a scoop, from which the water/sludge mixture is sucked in.

The aspirated mixture enters the tank, where it undergoes a first step of decantation and is sent by an Archimedes screw conveyor to a masher-homogenizer, thus making the mixture suitable for centrifugation and subsequent extruder.

During the mashing-homogenization step, the mixture has lost about 35/40% of its water content. The mixture is sent to a subsequent dehumidification process, de-centrifuged by the "single" pump, which acts on the mixture to recover a dry product with 30% water.

At the end of this step, the initial dry material is recovered with excess water and is ready for the next step of mixing.

To further reduce the water content, the mixture is sent to a drier capable of separating the water as steam at atmospheric pressure, followed by introduction of steam for final drying of the product.

At the outlet of the dryer, the treated material enters the tank, from which it is sent to the mixer via two Archimedes screw conveyors. Add polymer additives into the mixer, the maximum amount of polymer additives is 10%, add together with a specific catalyst, the amount of catalyst added is 20-50% of the main component, and add 5% CaO, 10% CaCO ₃ . The resulting product is passed through an extruder to pelletize the material.

The pellets are transported via a conveyor belt into an insulated container heated by coiled tubing. Steam from the dryer enters the coil.

Said conveyor conveys the final product to two containers heated by the same steam for complete drying.

The water obtained, ie from the main decantation and from all other operating steps, is sent to the vessel in which the first decantation was carried out. Thus, after passing through several mechanical filters, the water is returned to the river at a depth of about 3m below the water level, so as not to cause surface turbidity and make it easier for suspended particles to settle on the river bottom.

Thus, the whole process can be manipulated by the computerized unit using signals on the control board.

The resulting products for the different construction industries contain 90% sludge and 10% water, and due to the conversion of materials into inert products, substances between the following minimum and maximum percentages are added:

- polymer additives 3-10%;

- Specific catalysts, 20-50% of the main component;

- CaO (quicklime) 5-10%;

- CaCO ₃ (calcium carbonate) between 5-10%.

The dryer needs a burner of suitable capacity proportional to the size of the unit and needs to be fed with low-sulfur fuel oil. The device operates virtually continuously.

The operation process is basically uninterrupted, but for the sequential mixing steps of "feeding, mixing, and discharging", two tanks of suitable capacity to ensure the spontaneity of the device are suitably arranged on the upstream and downstream of the mixer.

Depending on its acceptability, the operating cycle can also be started with the upstream tank charge to ensure the mixer works perfectly. The mixer capacity corresponds to the unit size and the "fill, mix, discharge" cycle is based on the time determined by its capacity.

Immediately downstream of the mixer there is another tank, whose function is to ensure continuous feeding of the extruder, wherein the preheated material is extruded from the extruder and enters a conveyor belt installed in an insulated container. Drying of the material is achieved by steam circulation, after which the material is stored.

When the empty device is started, the sludge is transported from the settling tank to the masher under suitable conditions. Depending on plant capacity, the converted material is then sent to final storage tanks.

Using the above device, it takes about 3 minutes to process 3 tons of sludge. Depending on the amount of reactants used, about 480/500 kg of final product is obtained. And it takes 10-12 minutes to get 3t final product.

According to the method of the present invention, the material obtained from USR and/or sludge transformation is completely "inertized", does not contain microbial flora, has optimal physical-mechanical strength and does not release heavy metals.

The analysis carried out by the specialized research institute obtained the above characteristics and obtained the following results:

- Faecal Escherichia coli (coliformi fecali) = None;

- Salmonella = none;

- Staphylococci aurea = None;

- Pseudomonas Aerruginosa = None;

- Spores of closridi sulphite-reducer = None.

Furthermore, the heavy metals released from USR and/or sludge conversion mainly present in the obtained products are completely negligible:

-Cu=0.02mg/kg

-Cr＝＜0.01mg/kg

-Pb=0.03mg/kg

-Cd=<0.001mg/kg

It has also been confirmed that the converted material loses 25.5% in weight when placed at a temperature of 500° C., and the generated smoke is not harmful to humans.

Furthermore, by observing the chemical-bacteriological results, different kinds of materials can be obtained from the transformation products that can be used in the construction industry:

- civil, industrial and agricultural construction materials;

- Outdoor and indoor civil flooring materials;

- All kinds of urban furniture;

- collection manholes for hydraulic installations;

- Highway guardrail;

- sound-absorbing and heat-insulating panels;

- Agricultural and breeding preparations;

-Industrial flooring materials.

Furthermore, mortars and concretes can be obtained from inert granules.

The sample specific gravity of USR and/or sludge conversion material is as low as 0.67g/cm ³ , which is significantly lower than the specific gravity of inert substances usually bonded with concrete, thus endowing the product of the present invention with the possibility of various technical applications sex.

In view of the characteristics of the product obtained by the method and the device, the device has a wide range of uses.

Material samples were obtained by premixing municipal solid waste with sludge from domestic purification plants.

The "cement mortar" thus obtained is added to additives that lead to the mineralization of organic matter.

The transformation process is carried out with the aid of substances that take part in the reactions and are used to ensure the future utility of the product.

In addition, the present method uses CaCO ₃ to neutralize the plastic substance in the inertization additive, making it effective for fire resistance without releasing toxic fumes.

And since CaO generates a lot of heat during the reaction with water, the temperature rise destroys the encapsulated spores without any possibility of releasing them in the final product.

Thus, the resulting product is inorganic, spore-free, and heavy residues are negligible. Furthermore, it has good fire resistance, as confirmed by the analyzes carried out.

The compression results of the samples indicated that the maximum mechanical properties were obtained both qualitatively and quantitatively.

In fact, the characteristic value of the simple compression breaking tension varies on average around 340 kg/cm ² , which is the acceptable limit with respect to any other material considered.

Furthermore, for the cracking of the cube under flexure, it can be clearly noticed that the crack is always along the diagonal of the cube.

To describe the novel features of the product of the invention, a comparison is made with concrete.

The material of the invention with a flexural resistance on the order of 350 kg/cm ² reaches a value very close to very high grade concrete (550 kg/cm ² ), with a value of 28 kg/cm ² , comparable to concrete's 39 kg/cm ² .

Another data confirming the properties of the converted product is the setting behavior: there is absolutely no effect on the material.

In addition to these data, it must show high flexibility, significantly reduce curvature, but in any case achieve a highly acceptable flexible breaking load with no cracks in the product, and in no case without warning.

High deformability results in fairly low modulus of elasticity values, but provides absolutely linear and bi-directional curves.

The thermal conductivity is about 10% higher than one of the "concrete", but this difference is negligible considering that the material is compressed by an artificial vibrator which cannot completely avoid cavitation.

Avoid the above problems by using suitable vibrating equipment (vibrating plate).

In this way, it is possible to reduce the thermal conductivity percentage mentioned above to the limit of concrete.

The following data are presented for illustrative and non-limiting purposes only for products obtained according to the present invention using only domestic sludge.

All the tests mentioned above were carried out in the laboratory of ISTDIL SpA in Guidonia. The sample used is obtained from 90% domestic sludge, adding CaO and CaCO ₃ , mixing properly in the same proportion, then atomizing and treating with 10% polymer additive and specific catalyst.

                                                                     

Flexural resistance tests were performed on rods having the following dimensions:

It is 1000×120×120mm and strengthened by bonding four φ8 irons with modified adhesive along the axial direction. Two irons are located in the arch bottom area, and two irons are located in the arch back area, about 25mm from the corner.

The rod is placed on two supports, which are 800mm apart. Then focus on the middle part and apply a load of 2050Kgf for simple deflection.

The table below lists the results obtained. load Kgf 200 400 600 800 1000 1200 1400 1600 1800 2000 curvature mm 0.30 0.60 1.00 1.60 2.20 2.90 3.55 4.20 4.95 5.80

It has been confirmed that the sample breaks directly without cracks when it is stressed. Further from the experiments described below, the possibility of eliminating the residual elastic curvature was ruled out, and the fracture was determined to be brittle.

Comparing the fracture data obtained from the above data with the data of the prestressed 9×12cm inverted T-shaped bar, it can be noticed that the fracture value is higher, which is due to the fact that the latter does not break until the maximum concentrated load is 1300Kgf (data based on prefabricated plant Obtained from laboratory tests in the country).

Examining the force versus drop plot, note the fact that there are two regions of perfectly straight lines, indicating elastic behavior. Elastic Behavior Remains elastic until broken.

In addition to this test, other simple deflection tests were carried out on five unreinforced samples of 230×40×20mm, and concentrated loads were applied in the middle of the two support points with a distance of about 200mm. The results are shown in the table.

flex test sample number 1 2 3 4 5 unit load (from N/ ^mm2 ) 1.28 1.18 1.28 1.36 1.23 Curvature(mm) 4.10 3.78 1.59 3.69 2.96

                                     

Four samples of 4 x 4 x 17 cm were tested for coagulation performance at a temperature of +15-15 °C. All positive results were obtained after 25 cycles as no observable changes were found during the test.

Linear Thermal Expansion

The sample is tested under linear thermal expansion, and the unit deformation of the sample is displayed by the LY41 electronic deformation measuring instrument HBM connected with the UPM60 data acquisition instrument HBM. From this, the data listed in the following table were obtained: temperature 29.4°C 29.4°C 69.6°C 69.6°C deformation 2021μm/m 1628μm/m 2337μm/m 1041μm/m time 7 hours and 53 minutes later 15 hours and 15 minutes after start 7 hours and 49 minutes after start 15 hours and 47 minutes after start

The above table shows the deformation versus test time data. From the above data, it can be known that the elongation of the sample when heated and expanded is 1041 μm/n.

Sliding Friction and Wear

Tested according to the instructions of R.D.2234 of 16.11.1939.

For the course of 1,000m, the wear coefficient is 8.68mm.

Compression

A simple compression implementation test is carried out on four cube samples with a side length of 40 mm.

The average compression resistance per unit load was 3.86 N/mm ² .

The present invention has been described illustratively and not restrictively by preferred embodiments, it being understood that improvements and/or changes may be made by those skilled in the art without departing from the corresponding scope as defined in the appended claims.

Claims (6)

1. A method for the cold conversion of urban solid waste (USR) and/or sludge into inert substances, the method comprising the steps of: - feeding USR and/or sludge from the corresponding feeding lines; - introducing the material into the pulverizer to reduce the particle size and recover the water contained in it; - adding 5-10% by weight of CaO to the main component; - adding CaCO ₃ of 5-10% by weight of the main component; - adding 20-50% by weight of catalyst; - adding 3-10% by weight of the main component of a polymer additive selected from polyvinyl acetate and its derivatives, polyurethane and its derivatives, and styrene polymers and their derivatives; - Conveying the product to the forming and storage steps. 2. The method according to claim 1, characterized in that along the USR feed line there is provided a de-ironing plant with a mechanical compressor for the waste and a main rougher, in particular with four crown-cutting hammers . 3. The method according to any one of the preceding claims, characterized in that, downstream of said main crusher and upstream of said pulverizer, a rotary iron removal device with collecting comb and rotating sleeve, coarse material recovery system and the second masher. 4. A method according to any one of the preceding claims, characterized in that, according to the invention, a water recovery tank may be provided downstream of the shredder. 5. The method according to any one of the preceding claims, characterized in that said forming and storing steps provide a product forming line comprising a granulation line provided with a dehumidifier group and/or a line provided with Product lines for formwork shakers. 6. An apparatus for implementing a method according to any preceding claim, comprising all of the following components or a partial combination of these components: - at least one, preferably two concrete tanks to discharge USR (Urban Solid Waste) and sludge respectively; - at least one, preferably two, mobile overhead cranes provided with means for loading the conveyor belt provided with suitable tanks; - a first horizontal conveyor belt with feeding tanks for feeding the masher; - iron removal plant with waste mechanical compressor located above the first conveyor belt mentioned above; - Coarse primary masher with cutting hammer; - a second horizontal conveyor belt with a feeding tank feeding the rear sieve; - Iron removal equipment equipped with combs for collecting fine materials; - hexagonal rotary sieve; - a third horizontal conveyor belt located below the rotary screen, which collects the screened material and sends it to the mixer feed conveyor; - second cutting hammer masher; - a fourth inclined conveyor belt suitable for taking unscreened material to the second crushing process, provided with side walls along all its length, equipped with feeding tanks, discharge boxes and electric motors with reduction gears; - a fifth horizontal conveyor belt suitable for conveying crushed material to the rotary screen conveyor belt; - pulverizer-heater with water recovery; - a sixth inclined conveyor belt suitable for conveying crushed products to the feeding and discharging buckets; - CaO (quicklime) tanks; - CaCO ₃ (calcium carbonate) storage tanks; - storage tanks for polymer additives; - Ultimately a specific catalyst tank; - three more conveyor belts, two of which are horizontal and one inclined, the inclined conveyor belt is located under the bucket collection trough, which sends the screened material to the mixer in an alternating manner; - Paddle sealed mixer with supports, channels, safety guardrails, round section discharge hopper, observation hole, engine and reduction gear, inlet material weighing system and additive atomization system; - a tenth horizontal conveyor belt suitable for conveying the screened material to the extruder; - An eleventh horizontal conveyor belt suitable for conveying screened material to the product line.

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