ES2951680A1 - PROCEDURE FOR THE TREATMENT AND VALORIZATION OF DISCARDED MELAMINE SHEETS OR MELAMINE PAPER (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Procedure for the treatment and recovery of discarded melamine sheets or melamine paper. The present invention relates to a procedure for the treatment and recovery of discarded melamine sheets or melamine paper that comprises a first crushing stage, a second grinding stage in a pin mill and a third micronization stage in a mill. micronizer, to obtain a floury powder capable of replacing raw material in the manufacture of new melamine sheets or melamine paper. Therefore, the present invention is of interest to manufacturers of melamine sheets or melamine paper. (Machine-translation by Google Translate, not legally binding)

Description

DESCRIPTION

Procedure for the treatment and recovery of discarded melamine sheets or melamine paper

The present invention relates to a procedure for the treatment and recovery of discarded melamine sheets or melamine paper that comprises a first crushing stage, a second grinding stage in a pin mill and a third micronization stage in a mill. micronizer to obtain a floury powder capable of replacing raw material in the manufacture of new melamine sheets or melamine paper.

Therefore, the present invention is of interest to manufacturers of melamine sheets or melamine paper.

BACKGROUND OF THE INVENTION

Melamine resins are in a liquid state so they are commonly impregnated on the product of interest such as paper rollers. These melamine resins are synthesized based on the final specifications that are to be given to the products of interest to be impregnated. Furthermore, additives are commonly incorporated into these resins that provide color, antibacterial or antifungal properties, abrasion resistance or fire resistance, anti-fingerprint, anti-adhesion, etc.

An example of the use of said melamine resins to impregnate products of interest is a melamine paper production process, where said melamine paper can be decorative, white or unicolor paper. The first step is to introduce unwound paper into a first impregnation bath comprising liquid melamine resin with or without additives through a series of rollers. The resin soaks the paper which must be air dried, in one or several steps, in ovens at a carefully controlled temperature depending on the speed of the rollers. Subsequent impregnations of said dried paper are also possible. The paper impregnated with the resin is then cut to the desired size, normally meeting the standards imposed for the manufacture of MDF boards. (from the English Medium Density Fibreboard) or melamine boards, which are the boards used for the manufacture of domestic furniture such as tables, cabinets, shelves, parquet, etc. The finished product is automatically cut to the required size and palletized.

However, every year a large number of scraps are generated that, because they do not meet the dimensional standards for sale, are discarded and therefore pose a threat to people's health and the environment. Concern for the environment is a fact that is observed at all levels of society. The pollution produced by man's actions on this planet has reached unsustainable levels, and society is demanding solutions to reduce the impact of man's life on the planet, which is known as the "ecological footprint." environmental”. In this sense, the different scraps of melamine sheets or melamine paper should not be an exception. The inventors of the present invention are unaware of the existence of any treatment of said discarded melamine sheets or melamine paper to prevent their sending to landfill.

Therefore, it is necessary to develop new procedures to treat and valorize discarded melamine sheets and/or melamine paper and thus preserve natural resources and the environment.

DESCRIPTION OF THE INVENTION

The present invention relates to a procedure for the treatment and recovery of discarded melamine sheets or melamine paper that comprises a first crushing stage, a second grinding stage in a pin mill and a third micronization stage in a mill. micronizer to obtain a floury powder with a particle size less than or equal to 100 μm, of sufficient quality to be reused and therefore be susceptible to, for example, replacing raw material in the manufacture of new melamine sheets or melamine paper.

The main advantage of the floury powder obtained in the treatment and valorization procedure of discarded melamine sheets or melamine paper is that it does not require subsequent treatment, it can be incorporated directly into the hopper that comprises the liquid mixture of melamine resin and its additives substituting, for example, the white charge of the mixture; The floury powder obtained in the process of the present invention can replace TIO ² in a percentage by weight of between 10% and 15%.

It should be noted that the procedure for the treatment and recovery of discarded melamine sheets or melamine paper results in a performance of between 100 kg/h and 250 kg/h, which makes it economically viable.

In a first aspect, the invention refers to a procedure for the treatment and recovery of discarded melamine sheets or melamine paper (hereinafter the method of the invention) characterized in that it comprises the following steps:

a) shred the discarded melamine sheets or melamine paper in a chopping machine until they are smaller than 2 cm,

b) grinding the discarded melamine sheets or melamine paper with a size less than 2 cm obtained in step (a) in a pin mill comprising a perforated screening mesh of between 2 mm and 4 mm, using a frequency working speed less than 2000 rpm, to obtain a powder with a particle size less than or equal to 300 μm, and

c) micronize the powder with a particle size less than or equal to 300 μm obtained in step (b) in a micronizing mill using a working frequency less than 2000 rpm to obtain a powder with a particle size less than or equal to 100 μm, where said micronizing mill comprises

- a regulated mesh with an outlet diaphragm of between 700 μm and 1000 μm, - a suction mouth attached to at least one ventilation sleeve, where the suction mouth is configured to suck the dust that rises thanks to an air current hot that is generated inside the chamber of the micronizing mill and that has passed through the outlet diaphragm and where the ventilation sleeve is configured to cool the hot aspirated powder of particle size less than or equal to 100 μm and store it in the collection tank.

The term “discarded melamine sheets or melamine paper” is understood in the present invention as those remnants of melamine sheets or melamine paper that are considered waste products (waste) because they do not meet the dimensional standards for sale. , although at a technical level they maintain their properties. These are thin melamine sheets with a width of less than 1 cm and a length of at least 20 cm, light and fragile, and dry, impregnated melamine paper.

Step (a) of the method of the invention relates to shredding or shredding the discarded melamine sheets or melamine paper in a chopping machine to obtain a size smaller than 2 cm, preferably a size between 0.5 cm and 2 cm. . This first stage (a) is key to obtaining an adequate size, less than 2 cm, to be able to feed the pin mill used in stage (b) without clogging it.

Step (b) of the process of the invention refers to the grinding of the discarded melamine sheets or melamine paper with a size less than 2 cm obtained in step (a) in a pin mill comprising a metal mesh. screening perforation of between 2 mm and 4 mm, using a working frequency of less than 2000 rpm, preferably between 1600 rpm and 1800 rpm.

The smaller size of 2 cm of the discarded melamine sheets or melamine paper and the frequency at which the pin mill operates prevents the discarded sheets or paper from melting or caking, rendering the mill unusable and/or sticking to the walls of the piton mill blocking the perforated metal screening mesh.

The fact that the pin mill used in step (b) comprises a perforated screening mesh is an advantage since grinding and screening are carried out in the same pin mill. Thanks to the sieving mesh size between 2 cm and 4 cm, a product of discarded melamine or melamine paper is obtained, which is a powder with a particle size equal to or less than 300 μm. Note that said powder does not yet have the appropriate particle size to be reused as a raw material substitute in the manufacture of new melamine sheets or melamine paper.

Stage (c) of the process of the invention refers to the micronization of the powder with a particle size less than or equal to 300 μm obtained in stage (b) in a micronizing mill using a working frequency of less than 2000 rpm to obtain a powder with a particle size less than or equal to 100 μm, preferably between 1600 rpm and 1800 rpm, where said micronizing mill comprises

- a regulated mesh with an exit diaphragm between 700 μm and 1000 μm,

- a suction mouth attached to at least one ventilation sleeve, preferably to at least one fabric ventilation sleeve, where the suction mouth is configured to suck the dust that rises thanks to a current of hot air that is generated within the chamber of the micronizing mill and which has passed through the outlet diaphragm and where the ventilation sleeve is configured to cool the hot aspirated powder of particle size less than or equal to 100 μm and store it in the collection tank.

The micronized powder rises thanks to the current of hot air inside the chamber of the micronizing mill and only the powder smaller than that established in the outlet diaphragm crosses said diaphragm and is sucked in by the suction mouth. Thanks to the regulated mesh with an outlet diaphragm of size between 700 μm and 1000 μm and the suffocation of the powder at the outlet mouth of the mill, a floury powder of discarded melamine or melamine paper is obtained with a particle size less than or equal to 100 μm. Furthermore, it should be noted that the ventilation sleeves incorporated in the micronizing mill play a fundamental role for the storage in the final powder receiving tank since they significantly reduce the temperature at which the ground powder reaches and prevent the escape of the floury powder obtained. . In turn, the ventilation sleeves prevent the caking of floury dust and improve the economic viability of the procedure. Preferably, the micronizing mill comprises a suction mouth connected to more than one ventilation sleeve to ensure that the temperature is significantly reduced.

The advantages of obtaining a mealy powder from discarded melamine sheets or melamine paper for the production of new melamine sheets or papers are as follows:

• Avoid the generation of lumps in the liquid resin tank.

• A total and symmetrical implementation with the rest of the ingredients with a particle size less than or equal to 100μm in the formulation.

• Prevent a "grain" larger than 100 μm from getting stuck in the impregnation rollers by grating all the paper that circulates continuously.

Throughout the description and claims the word "comprises" and its variants are not intended to exclude other technical characteristics, additives, components or steps. For those skilled in the art, other objects, advantages and features of the invention will emerge partly from the description and partly from the practice of the invention. The following examples and figures are provided by way of illustration, and are not intended to be limiting of the present invention.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1. Scheme of industrial cross-cutting machine (1), pin mill (2) and micronizing mill (3).

Figure 2. Pin mill diagram (2)

Figure 3. Micronizing mill scheme (3)

EXAMPLES

Next, the invention will be illustrated through tests carried out by the inventors, which demonstrate the effectiveness of the inventive procedure.

Firstly, we obtain from clients the material that they classify as “waste” since it does not meet the correct measurements for sale, but meets 100% of the technical and qualitative characteristics. Said waste material is dry, fragile and light melamine sheets with a width of less than 1 cm and a length of about 20 cm that are received in bags or containers.

Secondly, the waste material is introduced into an industrial chopping machine (1) through its intake mouth (1a) until the material is obtained in the form of confetti with a size less than 2 cm that comes out through the exit mouth (1b). and is collected in the container (1c).

Said waste material smaller than 2 cm is introduced into a “Royal-Triumph” type self-ventilated (AV) pin mill (2) that comprises a crushing cavity (2a) and a perforated metal screening mesh (2b) of 3 mm and what is equipped with a 30 kW motor and a frequency converter (2c) to adjust the revolutions of the grinding plate. The crushing cavity (2a) of the pin mill (2) is prepared with 2 pin plates, one fixed and the other rotating, on which its revolutions were adjusted with the frequency converter (2c) to a value of 1600 rpm. . The revolutions were maintained at these values to avoid overheating of the pin mill (2) and to prevent waste material smaller than 2 cm from adhering to its walls. The perimeter of the crushing cavity (2a) incorporates a 3 mm non-adjustable perforated metal screening mesh (2b). The powder obtained is collected in the container (2d). The powder obtained in this case has a grain size less than or equal to 300 μm when the perforated screening mesh had a size of 3 mm.

The last step of the procedure is to introduce the powder with a particle size greater than or equal to 300 μm into a Bachiller-type micronizing mill (3). A regulated mesh with an outlet diaphragm (3e) of 800 μm has been incorporated into said mill (3) to obtain a floury powder with a particle size less than or equal to 100 μm. The powder with a particle size greater than or equal to 300 μm is incorporated into the micronizing mill (3) through the intake hopper (3a) through a two-worm screw (3b) with a speed variator (3c) to adjust the speed of feeding the mill (3) with the micronization capacity. The upper cover (3d) of the chamber (3f) comprises a regulated mesh with an exit diaphragm (3e) of a size of 800 μm. The dust rises thanks to the current of hot air inside the chamber (3f), crosses the outlet diaphragm (3e) and is sucked in by the suction mouth (3g). The suction mouth (3g) comprises four fabric ventilation sleeves (3h) through which the floury powder obtained with a particle size less than or equal to 100 μm is cooled and introduced into the collection tank (3i). The ventilation sleeves (3h) therefore allow the hot air to escape, but prevent the floury dust obtained from escaping. Due to its own weight, the micronized and aspirated powder with a particle size less than or equal to 100 μm descends and is collected in a container (3j).

Next, a granulometric study of the resulting product was carried out, obtaining the following granulometric characteristics:

- Rejection > 200 microns: 0.4%

- Rejection >150 microns: 2.9%

- Rejection >100 microns: 2.2%

- Rejection > 75 microns: 9.4%

- Rejection ≤ 75 microns: 85%

It should be noted that the procedure for the treatment and recovery of discarded melamine sheets or melamine paper presented in this exemplary embodiment results in a performance of between 100 kg/h and 250 kg/h, which makes it economically viable.

Comparative tests

Mention here the following conclusions from other tests carried out:

• If the shredding stage of the discarded melamine sheets or melamine paper is not carried out, the discarded sheets or paper melt, become caked, rendering the pin mill unusable and remain stuck to the walls of the pin mill, blocking Perforated metal screening mesh.

• If after the shredding stage of the discarded melamine sheets or melamine paper, only the grinding stage is carried out with the piton mill and a 3 mm perforated screening mesh with which a powder the size of particle less than or equal to 300 μm, the process slows down, discarded melamine sheets or melamine paper, making the performance of the pin mill economically unfeasible and resulting in an inadequate particle size.

• If after the shredding stage of the discarded melamine sheets or melamine paper, the grinding stage is carried out with the piton mill and a 3 mm perforated screening mesh with which a particle size powder would be obtained less than or equal to 300 μm and the working frequency is increased above 2000 rpm, the pin mill heats up and the discarded sheets or paper remain adhered to the walls of the pin mill, blocking the perforated screening mesh.

• After shredding the discarded melamine sheets or melamine paper to a size less than 2 cm and grinding them in a pin mill comprising a 3 mm perforated screening mesh, a powder with a particle size less than 300 μm. Said powder is introduced into a Bachiller-type micronizing mill that operates at a working frequency of less than 2000 rpm and that does not include ventilation sleeves (3h) and therefore does not cool the resulting product. Said procedure gives rise to an economically insufficient yield since the powder obtained becomes caked.

Claims (5)

1. A procedure for the treatment and recovery of discarded melamine sheets or melamine paper characterized in that it comprises the following steps: a) shred the discarded melamine sheets or melamine paper in a chopping machine (1) to obtain a size smaller than 2 cm, b) grinding the discarded melamine sheets or melamine paper with a grain size of less than 2 cm obtained in step (a) in a pin mill (2) comprising a perforated screening mesh (2b) of between 2 mm and 4 mm, using a working frequency less than 2000 rpm to obtain a particle size less than or equal to 300 μm, and c) micronize the powder with a size less than or equal to 300 μm obtained in step (b) in a micronizing mill (3) using a working frequency less than 2000 rpm to obtain a powder with a particle size less than or equal to 100 μm. , where said micronizing mill comprises - a regulated mesh with an exit diaphragm (3e) of between 700 μm and 1000 μm, - a suction mouth (3g) joined to at least one ventilation sleeve (3h), where the suction mouth (3g) is configured to suck the dust that rises thanks to a current of hot air that is generated inside the chamber of the micronizing mill (3f) and that has passed through the outlet diaphragm (3e) and where the ventilation sleeve (3h) is configured to cool the hot aspirated powder of particle size less than or equal to 100μm and store it in the collection tank ( 3i). 2. The method according to claim 1, where, in step (a), the discarded melamine sheets or melamine paper are shredded to obtain a size between 0.5cm and 2cm. 3. The method according to any of claims 1 or 2, wherein, in step (b), the discarded melamine sheets or melamine paper with a size less than 2 cm obtained in step (a) are ground in a piton mill using a working frequency of between 1600 rpm and 1800 rpm. 4. The method according to any of claims 1 to 3, where, in the step (c) the micronizing mill comprises a suction mouth joined to more than one ventilation sleeve. 5. The procedure according to any of claims 1 to 4, where, in step (c) the powder with a size less than or equal to 300 μm obtained in step (b) is micronized in a micronizing mill using a working frequency of between 1600 rpm and 1800 rpm.