The present invention relates to an industrial milling plant for tannery leathers, or similar flexible and special laminar surfaces, having an environmental impact more improved than the prior art plants since it is provided with a depuration system of the odor of the air released from the rotating drum belonging to the plant in which the leathers are treated by means of water and/or dedicated chemical products.

It’s worth noting that in the tanning industry, the term "milling" means the treatment of leathers in a machine, known as "drum", performed to prepare the leathers for tanning and to subject them to the processes of tanning, dyeing or greasing.

Typically, the parameters of a milling cycle recipe comprise: temperature inside the rotating milling drum and consequently, relative humidity.

These are the main parameters of a milling cycle which, however, further comprises other parameters such as operating speed (i.e., rotation speed) of the drum, total time of the milling cycle, chemical products introduced into the drum, and type of leathers treated in the drum, purity level of the air introduced into the drum and so on.

More in particular, milling is a mechanical type process which is carried out on any type of special fabric - generally, animal leathers - to give the product the appearance of aging or wrinkling, make it softer and eliminate any creases present and thus prepare it for the next processing steps.

Indeed, the material is subjected to mechanical action due to its rolling inside the basket or hollow cylindrical drum (often perforated), which constitutes the main part of the machine (or drum) and which materially operates by rotating around a transversal, usually horizontal, axis.

At the same time as the mechanical action, the material inside the cylindrical basket (or drum) can be conditioned by air subjected to predetermined temperature and humidity conditions.

Finally, the product is cooled by circulating cold air inside the cylindrical drum which is the main component of the milling drum. More or less intense effects on the leathers can be achieved by varying the processing time. In general, a known milling plant for leathers to be subjected to a simple fulling operation (the latter term is commonly used in the tanning industry to indicate the leather processing aimed at softening it by mechanical shaking inside the drum under regulated temperature and humidity conditions) comprises a milling drum which, in turn, comprises a substantially cylindrical hollow body adapted to be put into rotation about a symmetry axis by means of motorized means and in which the leathers to be treated are received.

A plant for milling leathers of known type further comprises a closed circuit (in the form of one or more pipes), operatively connected to the cylindrical and rotating hollow body of the milling drum for letting air in and out from the hollow body itself for treating the leathers.

Furthermore, a typical milling plant for leathers of the prior art comprises a dust collector for cleaning the air, arranged outside the cylindrical hollow body of the milling drum from which it receives air and downstream of the hollow body following, as a conventional reference direction, the air path within the closed circuit, as well as forced ventilation means, such as a fan, arranged downstream of the dust collector following, as a reference direction, the air path within the closed circuit.

In its essential aspects, a common milling plant of the prior art includes at least one exchange valve arranged downstream of the forced ventilation means following, as a reference direction, the air path inside the closed circuit, and a group of electrical resistors, arranged downstream of the exchange valve and outside the cylindrical hollow body, again following the air path inside the closed circuit as a reference direction.

In particular, the dust collector is mounted outside the milling drum, immediately downstream of the outlet of the cylindrical hollow body which distinguishes the latter, and provides a generic purification system of the air leaving the hollow body itself which, in general, is of the filtering sleeves (or bags) type supported by a supporting structure and enclosed by an outer casing which inhibits uncontrolled access by anyone (unless of course the component parts are disassembled).

The filter sleeves are notoriously used for dry and liquid industrial dust collection, by means of the separation of particles, dust, or impurities (above all residues of the leathers being processed in the rotating drum) in suspension in the air, by virtue of the materials with which they are made and which range, for example, from polyester to polypropylene, cotton, wool-nylon compound or technical fabrics. Substantially, the impurities in the air which enters into the filtering sleeves of the dust collector progressively stick to the inner wall of the sleeves themselves and from here they decant by gravity downwards until they accumulate in a removable collection box located in the lower part of the dust collector and accessible by the operator.

The filtering sleeves are subjected to maintenance in the factory (this is possible, as mentioned, only by removing the outer casing of the dust collector) periodically, generally once a week or every ten to fifteen days according to the operational choices, while the removable collection drawer is emptied more frequently, even two or three times a week.

Despite the fundamental and effective action of the dust collector, at present, in the tannery sector, the negative fact persists that the air exiting firstly from the drum and then from the dust collector still has a pungent and unpleasant odor and still contains finer and residual volatile substances, substantially molecules produced by the leather processing, which continue to recirculate in the closed circuit and, thus, negatively introduced into the rotating drum again, except when the exchange valve, downstream the ventilation means, is opened, which disperses the substances into the environment (either outside or inside a building), however together with the odor.

Furthermore, the foul odor which is produced by the processing of leathers inside the rotating milling drum permeates the leathers themselves to the extent that they carry the odor with them even after the numerous and successive processing steps carried out in the tanning industry and until they are applied to the finished manufactured item (such as a sofa or a car seat) and the latter is used in domestic or closed environments (such as e.g. the living room of a house or the passenger compartment of a car).

Therefore, the present invention suggests to remedy the aforesaid disadvantages starting from the awareness of the aforesaid drawbacks suffered by the prior art considered hereto. In particular, it is primary purpose of the invention to provide an industrial leather milling plant with an improved environmental impact, which allows eliminating or at least drastically reducing the foul, unwholesome, pungent, intense, and in any case, unpleasant odor produced by the leathers being processed in a milling drum and present in the air recirculating in the closed circuit of the plant itself or emitted into the environment.

In other words, it is main purpose of the present invention to make available an industrial leather milling plant with an improved environmental impact, which allows improving the quality of the air circulating in the closed circuit of said plant and periodically released into the external environment of the plant (which can be the closed environment of a factory or the open-air environment, external to the latter), through the opening of the exhaust valve.

Within this purpose, it is therefore task of the present invention to devise an industrial leather milling plant which, compared with the prior art, promotes healthier or at least more pleasant working conditions for operators in a manufacturing plant in which such a plant is present.

It’s another task of the invention to indicate an industrial leather milling plant which has an environmental impact, in terms of atmospheric emissions, much better than the known equivalent plants, guaranteeing healthier and, therefore, safer conditions also for the people who are not only frequently or permanently but also only temporarily in the environment outside the factory where the plant is installed. It’s a further task of the present invention to make an industrial leather milling plant which allows to get an overall disinfection of its component elements, in particular of the milling drum in which the treatment of the leathers actually takes place.

It’s a not last purpose of the invention to provide an industrial leather milling plant which promotes greater sanitization, in terms of deodorization, of the leathers than that offered in the prior art, to the extent of substantially eliminating or at least greatly reducing the typical residual odor on the finished manufactured items, such as an automobile seat or a home chair) in which they are used.

Said purposes are achieved by means of an industrial leather milling plant with an improved environmental impact as illustrated in the appended claim 1 , to which reference is made for the sake of brevity. Further detailed technical features of the industrial milling plant for tannery leathers of the invention are contained in the corresponding dependent claims.

The aforesaid claims, hereinafter specifically and concretely defined, are integral part of the present description.

Advantageously, the industrial leather milling plant of the invention can improve, with respect to the background art, the quality of the air circulating within the closed circuit belonging to it, as well as of the environment into which the air is periodically expelled.

In the invention, the air circulating in the closed circuit of the plant is treated downstream of the milling drum and, therefore, coming from and exiting the rotating hollow body (cylindrical or octagonal) of the milling drum in which the mechanical processing and conditioning of the leathers takes place.

This is favorable because the industrial leather milling plant of the invention comprises additional means for purifying, deodorizing, disinfecting, depurating, or sanitizing the air, arranged outside the hollow body of the milling drum, in line with the closed circuit and externally downstream of the dust collector, operatively connected to actuation means adapted to activate such additional purification means not only to reduce but also to almost totally eliminate the unwholesome and unpleasant odor which accompanies the air coming from the milling drum in which it was permeated by the odor emanating from the animal leathers being processed.

Equally advantageously, relative to the prior art, the industrial leather milling plant of the present invention offers more pleasant working conditions to the operators of the production plant in which the plant is installed, precisely by virtue of the substantial elimination of the odor of the air circulating in the plant and emitted into the environment.

Equally advantageously, the industrial leather milling plant of the present invention is also more respectful of the environment outside the factory in which the plant itself is installed, because this external environment is also positively affected by the innovation resulting from the invention which ensures air in which the typical odor resulting from the processing of leathers is practically absent or present in an irrelevant quantity. More advantageously, the industrial leather milling plant with an improved environmental impact of the invention also favors a greater sanitization, depuration, or deodorization of the leathers than that offered by the technologies of the prior art, so that the finished items (such as a car seat or a sofa, an armchair or a house chair) also obtained with leathers are substantially free from the typical and unpleasant residual odor which, at least on an emotional level, impacts the opinion of the quality of the leather to be worked received and purchased from the tanning company expressed by the manufacturer of such finished manufactured item (and also by the final retailer).

Advantageously, the additional purification means present in the industrial leather milling plant of the invention allow a favorable overall disinfection of the component elements of the plant, especially of the milling drum housing the treatment of the leathers.

Said purposes and advantages will be more apparent from the description that follows, related to preferred embodiments of the industrial leather milling plant with an improved environmental impact of the invention, given by way of indicative and non-limiting example, with reference to the appended drawings, in which:

- figure 1 is a diagrammatic and exemplified side view of a first variant embodiment of the plant for milling leathers of the invention;

- figure 2 is a diagrammatic and exemplified side view of a second variant embodiment of the leather milling plant of the invention;

- figure 3 is a diagrammatic and exemplified side view of a third variant embodiment of the leather milling plant of the invention;

- figure 4 is a diagrammatic and exemplified side view of a fourth variant embodiment of the leather milling plant of the invention.

A first embodiment of the industrial leather milling plant of the invention is illustrated in figure 1 where it is indicated as a whole by the reference numeral 1 .

As noted, the industrial milling plant 1 comprises:

- a milling drum 2 comprising a hollow body 3 (for instance cylindrical or octagonal), which is rotated around a symmetry axis X (usually horizontal) by means of motorization (not shown for the sake of simplicity) and inside which the leathers to be treated are received by mechanical shaking to soften them; - a closed circuit 4, operatively connected to the hollow body 3 of the milling drum 2 to allow the introduction of air A into and out from the hollow body 3, which air is useful for the aforesaid, so-called fulling treatment of the leathers;

- a dust collector 5 to clean the air A from the particles, impurities, or volatile dust released by the leathers, arranged outside the hollow body 3 of the milling drum 2 from which it receives the air A and downstream of the hollow body 3 following, as a hypothetical or conventional reference direction, the path made by the air A inside the closed circuit 4;

- forced ventilation means, indicated as a whole by reference numeral 6 and comprising, for example, a fan, arranged downstream the dust collector 5 following, as a reference direction, the air path A inside the closed circuit 4;

- an exchange valve 7 arranged downstream the forced ventilation means 6 again following, as a reference direction, the path of the air A in the closed circuit 4;

- a single (in the specific and preferred case) electrical resistor 8, arranged outside the rotating hollow body 3 and downstream of the exchange valve 7, still following, as a reference direction, the path of the air A inside the closed circuit 4.

According to the invention, the industrial milling plant 1 for leathers with an improved environmental impact of the invention comprises additional purification means of the air A, indicated as a whole by the reference numeral 9, arranged outside the hollow body 3 of the milling drum 2, in line on the closed circuit 4 and externally and conveniently downstream the dust collector 5, operatively connected to actuation means (not shown) adapted to activate the additional purification means 9 to at least reduce the unwholesome and however unpleasant odor which accompanies the air A coming from said milling drum 2.

By way of preferable but not limiting example, the dust collector 5 is of the classical type with filtering sleeves (or bags) 10, 11 (generally two) for the collecting the dust of gaseous currents, made of material with clinging or holding capacities chosen by the group consisting of the fabric of natural and/or manmade fibers (e.g., in the materials already identified above) in staple, continuous thread or monofilament, felt form or similar materials and, in its lower part 5a, comprises a removable collection box 12 in which particles, impurities or volatile dust P of the leathers accumulate, initially suspended in the air A captured by the inner wall 10a, 11 a of the respective filtering sleeves 10, 11.

In a particular and preferred but not exclusive manner, the additional purification means 9 of the air A comprise an ozonator 13 arranged within a conveying pipe (only diagrammatically shown in the attached drawing table 1/1 , wherein it is indicated by reference numeral 14) of the air A belonging to the closed circuit 4.

Preferably, the ozonator 13 comprises any of the ozone generators selected by the group consisting of corona-effect generators (the preferred and best performing solution in the industrial application of the present invention), cell generators, ultraviolet lamps, electrolysis cells and/or combinations thereof.

Figure 1 shows the additional purification, depuration, sanitization or disinfection means 9 are also, in general, installed upstream the electrical resistor 8; in this case, particularly, they’re installed upstream the forced ventilation means 6.

It is understood that in other constructive variants of the industrial leather milling plant with an improved environmental impact of the invention, not shown in the following figures, the additional air purification means may comprise a number of ozonators higher than one, according to the design choices, installed as desired on the closed circuit and in any case upstream of the electrical resistor and downstream of the dust collector.

The specific installation of the ozonator 13 downstream of the dust collector 5 - to be understood as outside of the load-bearing casing 15 in which the filter sleeves 10, 11 are housed - provided in the industrial plant 1 of the invention is convenient because it prevents the ozone thus produced from being negatively and inefficiently absorbed or consumed by the dust, particles or impurities P which are separated from the air by the filter sleeves 10, 11 in the dust collector 5.

The ozonator 13, on the other hand, absorbs, degrades, or breaks down the volatile organic substances (or charges) (such as odor) - much finer than dust, particles, or impurities P - present in form of molecules in the air A.

Furthermore, providing the ozonator 13 has the advantage of allowing ozone to be produced directly on-site and only when needed, required, or scheduled and to act effectively against bacteria, viruses, and mold in the air A itself. The constructive solution shown in figure 1 is thus the preferred and most suitable constructive solution of the invention among those available and in any case functional, especially in relation to the technical problem that the invention itself intends to solve, providing the detection means 9 almost immediately upstream of the electrical resistor 8 and not far from the dust collector 5, thus effectively fulfilling a need for balancing two at least partly conflicting positions.

The concentration of ozone produced by the ozonator 13 depends on the power of the electrochemical cell which generates it, but it can also be increased by increasing the concentration of oxygen in the air which crosses through the cell itself; this can be achieved essentially in two different manners: the first by blowing oxygen near the electrochemical cell, the second by generating oxygen by chemical reaction near the cell itself. Typically, therefore, it is either an organic or inorganic reaction capable of developing gaseous oxygen, respectively.

Preferably but not necessarily, the actuating means comprise a central processing and control unit, not shown for the sake of presentation simplicity, electrically connected to the additional purification means 9 of air A to manage the operational, activation, and deactivation cycles thereof, and which, more generally, manages the operation of the industrial plant 1 as a whole, also storing the processed data.

The following figure 2 shows a further variant embodiment of the invention in which the industrial leather milling plant, now indicated as a whole by reference numeral 50, differs from the previous one indicated by reference numeral 1 only for the position of the additional purification or depuration means, indicated as a whole by reference numeral 59, on the closed circuit 54; indeed, in this case, while remaining upstream of the electrical resistor 58, the additional purification means 59 are installed downstream not only simply of the dust collector 55 but also of the forced ventilation means 56 and upstream of the exchange valve 57.

Therefore, in brief, in the optional embodiment shown in figure 2, the additional purification means 59 (such as an ozonator 60) are installed between the forced ventilation means 56 and the exchange valve 57; this alternative construction is also very advantageous and useful for achieving the predetermined objects of the present invention. Another solution idea of the invention is shown in figure 3, in which the industrial leather milling plant, now indicated as a whole by reference numeral 100, differs from those already described above, respectively indicated by reference numerals 1 and 50, only for the position of the additional purification means, indicated as a whole by reference numeral 109, on the closed circuit 104; indeed, in this case, the additional purification means 109 of the air A are installed upstream of the electrical resistor 108 and downstream also of the exhaust valve 107 and not only just of the dust collector 105 and the forced ventilation means 106.

Finally, figure 4 shows a further constructive solution of the invention in which the industrial leather milling plant with an improved environmental impact, now indicated as a whole by reference numeral 150, differs from the three industrial plants 1 , 50, and 100 described above again for the position of the additional purification means, indicated as a whole by reference numeral 159, which in this case are installed downstream of the electrical resistor 158 and upstream of an inlet 160 of the hollow body 153 of the milling drum 152.

This variant embodiment of the invention is also suitable, in particular, for assessing whether particles, dusts or impurities of any kind enter the closed circuit 154 and the hollow body 153 of the milling drum 102 from the outside, and, if necessary, provide the at least partial purification or sanitization of those entering, although such a solution of the invention appears the least suitable for the technical problem that the invention suggests to overcome.

By virtue of the aforesaid description, it is thus apparent that the industrial leather milling plant with an improved environmental impact of the present invention achieves the purposes and offers the previously mentioned advantages.

The industrial leather milling plant with an improved environmental impact of the invention allows obtaining odorless leather, with consequent positive effects downstream, such as in particular the satisfaction of the final customer (intended as the person who buys the tanned leather and processes it to obtain finished manufactured items, such as, above all, car seats and furniture, not excluding, however, leather shoes and fashion accessories, such as bags and suitcases).

Upon implementation, modifications may be made to the industrial leather milling plant with an improved environmental impact of the invention, consisting for instance of a different number of electric resistors and exchange valves from those previously described and illustrated in the accompanying figures, because both these numbers may vary according to the construction choices starting from one. Furthermore, other embodiments of the industrial leather milling plant which is exclusively disclosed hereafter, not shown below, in which additional purification means have a constructive concept different from that described above without impairing the advantage provided by the present invention.

In addition, in other embodiments of the industrial leather milling plant with an improved environmental impact of the invention, not shown in the attached drawing tables, the additional air purification means can be arranged in several points along the closed circuit, again respecting the essential requirement provided for by the characterizing part of the original claim 1 attached (according to which the additional purification means are arranged outside the rotating hollow body of the milling drum and externally downstream of the dust collector); in such cases, in which the level of air deodorization will be maximum or in any case strongly elevated, the industrial leather milling plant with an improved environmental impact of the present invention will appear as one of the possible combinations of the embodiment versions described above and shown in the accompanying figures.

Finally, it is apparent that many other variants may be made to the industrial leather milling plant with an improved environmental impact, without departing from the principles of novelty inherent in the inventive idea, just as it is apparent that in the practical implementation of the invention, the materials, shapes, and sizes of the details shown may be any according to the requirements and may be replaced by other technically equivalent elements.

Where the constructive features and techniques mentioned in any successive claims are followed by references signs or numerals, such reference signs were introduced for the sole purpose of increasing intelligibility of the claims themselves and consequently, such reference signs have no limiting effect on the interpretation of each element identified by way of example only by such reference signs.