CN1219975A - Method and apparatus for treating leather etc. - Google Patents

Abstract

According to the process of treating leather and the like, spread pieces of leather to be treated (1) are put on respective open supports (2). These supports (2), with spread pieces of leather carried thereon, are introduced into at least one container (4), kept in depression and sealed for the introduction therein of suitable treating liquid solutions so that at least soaking, liming, pickling, tanning and re-tanning steps can be performed on the leather pieces. Each liquid solution (5) is swirled during the corresponding leather (1) treatment step.

Description

Method and apparatus for treating leather etc.

technical scope

The present invention relates to a method for tanning leather and the like.

current technology

It is already known that animal hides are tanned with various solutions which remain irreversibly fixed to the hide, making the animal hide tanned so as not to rot.

This process comprises different steps, which are often complex and require a relatively long time.

When the hides are sent to the tannery, where they are usually dried with salt, the hides are first prepared for the real tanning.

This preparation first includes a soaking step, which removes impurities covering the flesh and grain of the hide, and an embalming solution to restore the leather to its natural suppleness.

The leather to be treated is soaked in a drum filled with a suitable liquid solution.

These drums contain fixed paddles or stakes which act on the hide during the rotation of the drum.

Therefore, this treatment consists of both the chemical action of the liquid solution and the mechanical action on the leather, and its duration is 6-24 hours.

This is followed by a shaving step, which removes the fat from the water-soaked hide, followed by a liming treatment to remove the hair and reveal the real hide.

Liming is carried out in suitable drums filled with an alkaline substance such as sulphide or lime, which swells the leather tissue and dissolves the hair roots.

More precisely, the leather is swollen, the fat is converted into calcium salts, and the proteins that make up the leather are denatured due to the breakage of primary and secondary bonds in the protein chains, and the hair is subsequently separated from the leather.

The substances used for liming and at the same time for "opening" the pores of the leather for actual tanning and dyeing are highly polluting, causing all known problems of waste disposal and/or purification. The liming step usually takes 24 hours.

The leather thus prepared is then again delimed and softened in suitable drums. As a result of the deliming step, residual lime is usually removed with deliming salts.

Softening is a biological action in which the grain of the leather is softened with enzymes which partially dissolve the elastic fibers and loosen the leather.

The leather is then pickled, or treated, to ensure a more rapid and complete penetration of the tanning salts.

In fact, softened leather (with an alkaline reaction) cannot be tanned with, for example, tanning chrome salts because it causes a chemical reaction that blocks the pores of the leather.

Therefore, the leather is acidified with a small amount of acid in the presence of salt (usually sodium chloride) in order to prevent swelling. This step takes place in a rotating drum and lasts an average of 10-12 hours.

The actual tanning treatment takes place in the aforementioned drums with vegetable solutions (such as natural or synthetic tanning solutions) or inorganic salts (mainly chromium salts, etc.).

The steps of liming, softening, pickling and tanning take an average of not less than 48 hours in total (it varies with the type of leather to be treated).

It is advisable to squeeze the tanned leather to remove part of the absorbed water, select and shave it, and then carry out dyeing treatment, or retanning. This staining step takes an average of 8 hours.

Therefore, as stated, the above mentioned tanning process takes a long time, it may take an average of a week.

In order to obtain a sufficiently high production rate, it is therefore necessary to use a relatively large number of large drums. The pieces of leather to be treated are placed in large quantities in drums and are directly subjected to mechanical action, which can sometimes damage the hide.

A major disadvantage of the conventional tanning process is that the working environment is very hazardous mainly due to the noxious gases emitted by the decaying organic matter produced by the aforementioned drums.

Furthermore, there are serious problems in the disposal of the waste liquid discharged at the end of the above-mentioned treatment process, especially the used material for liming.

Summary of the invention

The object of the present invention is to provide a method which allows tanning of leather etc. in a shorter time than known systems and which guarantees high quality tanned leather and High productivity with low energy consumption.

Another main object of the present invention is to provide a method which can be carried out with such an apparatus which can be operated in a non-hazardous working environment and in which the problems associated with waste disposal are considerably alleviated.

Another object of the present invention is to provide such a process which, at the same quality of tanned leather, can substantially reduce the amount of substances used.

Another object of the present invention is to provide a method that is carried out without polluting the air.

Moreover, another object of the present invention is to provide an apparatus for implementing the above method.

The above objects are achieved by a method of treating leather etc., which method comprises:

The unfolded leather to be treated is put into the container separately; the liquid solution is sent into the container according to the predetermined time interval and order for each step of leather tanning treatment, and after each step is completed, the liquid solution is removed from the container draining; keeping the interior of said container under negative pressure at least in each single step; generating a relative movement between the liquid solution and said piece of leather during each step in order to intensify the action of said liquid solution on the leather .

The method is carried out using a device comprising: a closed container; a plurality of racks, which can be put into and taken out of said container, on which the corresponding unfolded leather sheets are fixed, and which racks are thus placed in said containers in such a manner as to keep the pieces of leather at intervals; a first series of storage tanks containing predetermined liquid solutions for the respective leather treatment steps; switchgear and control equipment which connect each of said storage tanks connected to the container, so that the relevant liquid solution used in the corresponding leather treatment step is sent therein; an evacuation device for maintaining a negative pressure in said container at least when the leather treatment step is carried out; between the liquid solution and said leather sheet A device for generating relative motion in order to intensify the action of said liquid solution on the leather.

According to another embodiment, the method comprises:

A step in which the unfolded pieces of leather to be treated are contained in containers spaced apart from each other; a liquid solution is introduced into said containers for the purpose of carrying out a leather tanning process; while said steps are carried out, said containers are kept under negative pressure; during the above steps wherein, relative motion is generated between the liquid solution and the leather sheet, so as to intensify the effect of the liquid solution on the leather sheet; discharge the liquid solution from the first container; discharge the liquid solution from the first container Take out the leather pieces in the container; repeat the above operation in another container for the remaining steps of the leather tanning process.

According to another embodiment, the device comprises:

A number of sealed containers, in which the predetermined leather treatment steps are carried out; a number of supports which can be loaded into and taken out of the containers, to which the corresponding unfolded leather pieces are fixed, which are placed in such a way that said containers, so that the leather pieces are separated from each other; a first series of storage tanks containing predetermined liquid solutions for the corresponding leather treatment steps; opening/closing devices and control devices, which communicate said storage tanks with the corresponding containers, The relevant liquid solution for feeding into the corresponding leather treatment step; the evacuation device for maintaining a negative pressure in each said container at least during the performance of the relevant leather treatment step; the corresponding liquid solution in each said container A device that generates relative motion with the leather sheet to enhance the action of the liquid solution on the leather.

Other features and characteristics are pointed out in the dependent claims.

Brief introduction to the drawings

The features of the invention will be pointed out in the following description, particularly with reference to the accompanying drawings, in which:

- Figure 1 is a plan view of the equipment for the support of leather sheets to be processed;

- Figures 2a, 2b and 2c represent views of the containers in which the above-mentioned support devices are respectively placed in different arrangements;

- Figure 3 represents a vertical section of the container during a step in the treatment of leather;

- Figures 4a and 4b represent diagrams of equipment for carrying out the corresponding tanning treatments according to the method of the invention;

- Figures 5a, 5b represent diagrams of two different embodiments of the aforementioned apparatus carrying out the method of the invention in different ways;

- Figure 6 represents a possible plant diagram for carrying out the method of the invention in another way;

- Figure 7 represents another embodiment of the device;

- Figure 8 represents a structural variant of the equipment container;

- Figures 9a and 9b represent two plant diagrams for recovery of steam under two operating conditions.

Best Mode for Carrying Out the Invention

Referring to the above drawings, numeral 1 designates a piece of leather to be tanned according to the present invention. According to the method, the leather pieces to be treated are spread out on respective open supports, eg frame 2 in FIG. 1 . The leather sheet 1 is stretched onto the frame 2 by means of a series of expanders of known type.

The frame 2 supporting the unfolded leather sheet 1 is placed in a container 4 and, according to a preferred embodiment, the frame is secured and the container is closed for treatment with a suitable liquid solution introduced into it.

The frames 2 supporting the unfolded leather pieces 1 are loaded into containers 4 at regular intervals, preferably arranged vertically, as seen in Figure 2a.

However, it is also possible to mount the frame 2 in the container 4 horizontally ( FIG. 2 b ) or obliquely.

With the leather pieces mounted vertically, it is entirely possible to hang the leather pieces on suitable stands (not shown) so that they are spaced from each other.

As shown in the example of FIG. 3, the upper part of the container 4 containing the treatment liquid solution is closed with a cover 6. As shown in FIG. In the lower part of the container 4 it has a stand 7 for supporting the frame 2 with the leather sheet 1 .

Inside the vessel 4 there is also a heat exchanger 8 which heats the liquid solution 5 to the desired temperature. During the treatment of the leather sheet spread out on the frame 2, the liquid solution 5 in the container 4 is turbulent. To this end, the container 4 is provided with a conveying element 9, which, below the support seat 7 of the frame 2, consists of a grid with a series of injection openings 10 from which air is injected to form bubbles.

Above the liquid solution 5 in the container 4, a negative pressure is maintained with suitable evacuation equipment 11, which is connected to the container through a line 110 through one of the two neutralization storage tanks 111a and 111b (the storage tanks will be below describe). The advantages of maintaining a negative pressure in the container 4 will be discussed below.

Furthermore, due to this negative pressure, air is sucked in from the outside by flowing through the conveying element 9 . In addition, negative pressure reduces the energy consumed to reach the desired operating temperature. Alternatively, the aforementioned air flow can also be obtained by means of a suitable compression device connected to the conveying element 9 .

In the following, the same numbers will denote devices performing the same functions. The plant for the tanning treatment shown in FIG. 4 a comprises a series of tanks 12 , which are preferably closed and which contain the liquid solution intended to be supplied to the treatment vessel 4 described above.

Specifically, there are four storage tanks 12a, 12b, 12c, 12d for supplying liquid solutions corresponding to the watering, liming, pickling and tanning steps. During the tanning process, the leather is also dyed, if desired. The storage tanks are equipped with respective heat exchangers 13a, 13b, 13c and 13d which maintain the liquid solution at the desired temperature. The heat exchangers 13a, 13b, 13c and 13d are controlled by the control unit 14 through the connections shown as S1, S2, S3 and S4.

The supply tanks are connected to injection pipes 15a, 15b, 15c and 15d each equipped with associated pumps 16a, 16b, 16c and 16d, which are controlled by the control unit 14 through the connections indicated by P1, P2, P3 and P4. The injection pipes 15 a , 15 b , 15 c and 15 d are connected to the container 4 and the injection pipe 17 via a valve 18 controlled by the control unit 14 .

The bottom of the container 4 is equipped with an outlet pipe 19 and a pump 20 controlled by the control unit 14 . Outlet pipe 19 is connected through valve 21 to discharge pipes 22a, 22b, 22c and 22d, which communicate with waste storage tanks 23a, 23b, 23c and 23d of the liquid solution used in container 4, respectively. Waste storage tanks 23 communicate with corresponding feed storage tanks 12 via respective return lines 24a, 24b, 24c, 24d, on which are provided respective pumps 25a, 25b, 25c, 25d, controlled by control unit 14.

As an alternative construction, discharge lines 22a, 22b, 22c and 22d are all connected to a single header (not shown) which is connected to a suitable scrubber.

In practice, the liquid solution withdrawn from the relevant supply tank 12 is sent to the container 4 for each of the above-mentioned tanning treatment steps.

According to a preferred embodiment, the apparatus also includes at least two other tanks 30a, 30b for washing liquid solution, described hereinafter, equipped with associated spray pipes 31a, 31b and controlled and associated with the control unit 14. Pumps 32a, 32b. These lines are connected to the inlet line 33 of the container 4 via a valve 34 controlled by the control unit 14 .

The aforementioned outlet line 19 connected to the bottom of the container 4 may also be connected via a valve 21 to one or the other of the discharge pipes 35a, 35b, flowing into the storage tanks 30a, 30b, respectively.

Inside the container 4, in the liquid solution, as described above, a turbulent flow of the liquid solution is created by the generated air flow.

It should be pointed out that before each single step is carried out, more precisely, before the liquid solution is introduced into the container, a negative pressure is generated in the container, so as to swell the leather and make the leather spongy, so that the liquid solution has no effect on the leather. The role is easier.

The aforementioned turbulence produces a massaging action on the leather sheet which replaces the mechanical action of known systems without damaging the leather.

When each of the described processing steps is completed, the spent liquid solution is withdrawn from the container 4 and sent to the associated waste storage tank 23 . After regeneration by techniques known to those skilled in the art, the solution can be reintroduced into the corresponding feed storage tank 12 for a new tanning cycle.

Water immersion treatment with liquid solution contained in storage tank 12a; water, possibly with chemical accelerators;

Since the negative pressure is created before the liquid solution is introduced, the leather absorbs water more easily as the leather tends to naturally swell and thus become more spongy, as described above. The combined effect of these factors, namely negative pressure and turbulent flow, shortens the time required for the immersion step. When the soaking is completed, the leather pieces are washed with the water contained in the storage tank 30a.

Liming treatment is performed with the liquid solution contained in the storage tank 12b according to an oxidation method using, for example, sodium hypochlorite or an enzyme agent. It should be noted that sodium hypochlorite cannot be used in the liming step carried out in wooden drums because sodium hypochlorite liberates chlorine which causes wood corrosion. As it is aspirated by the evacuation device 11 and exhausted through line 110, the chlorine enters one of the storage tanks 111a, 111b which contains sodium dithionate which neutralizes the chlorine, as is known. In this way, the evacuation device 11 is protected and at the same time the problem of disposal of the substances used in the liming process is solved. In this case, the combined action of the negative pressure to swell the hide, the sodium hypochlorite and the massaging action of the turbulent air on the hide completes the liming process.

It has great advantages for the following reasons:

- the use of a substance whose disposal (more precisely neutralization) is not very troublesome;

- Due to the negative pressure in the working environment, the energy consumption is reduced;

- The leather is not subject to mechanical stress.

It should also be noted that swelling of the leather also opens up the pores, which facilitates subsequent tanning and dyeing treatments.

The liming step takes about 5 hours. After liming, the leather is washed with the contents of storage tank 30b. The liming step is followed by the pickling step, which is carried out with the contents of the storage tank 12c; the effect of this operation is enhanced by the massaging action on the leather by the turbulent flow.

Tank 12d contains a liquid solution for the actual tanning step and, if desired, also for the dyeing step, the latter being carried out with a colorant (for example a vegetable colorant) dispersed in the liquid.

The liquid solution may also contain an agent which makes the leather easier to lubricate. Due to the negative pressure, the pores remain open, reducing the time required to complete these steps. The amount of tanning and dyeing substances is reduced compared to conventional methods.

In fact, under the conditions described (i.e. the leather swells and is therefore more spongy), the concentration of tanning and dyeing agents in the liquid solution decreases compared to known systems, (tanning and dyeing agents from the liquid solution transfer to the leather, where they are irreversibly fixed), so the quantities of these reagents are lower, but the quality of the results obtained is still the same. The pickling, tanning and dyeing operations take about 24-36 hours.

It is known that the actual tanning treatment can be carried out with so-called pretanning agents, while simultaneous dyeing with leather fatliquor (also called retanning) can be carried out separately from and after the actual tanning treatment.

In Fig. 4b, the equipment for completing the above-mentioned modification is illustrated, wherein numeral 12e represents a storage tank containing liquid pre-tanning product liquid, 23e represents a storage tank containing waste liquid after completing pre-tanning, and 30d represents a storage tank containing waste liquid after completing pre-tanning. Tanks for the solution of washing the leather after tanning, 12f denotes the tank for the liquid solution used for leather retanning and fatliquoring, 23f denotes the tank for receiving the waste from the container 4 after the last step is completed.

In general, the process of the invention has proven to allow the tanning of leathers in a considerably shorter time compared to conventional techniques, while guaranteeing high quality tanned leathers.

By spreading the leather over the frame 2, the turbulent movement due to the air flow in the liquid solution 5 (with which it is treated) and the effect of negative pressure also contribute to this result.

In particular, it should be pointed out that the leather sheet is not subjected to strong mechanical stresses, but only to the massaging action produced by said turbulent movement, thus having a clear quality advantage.

An important feature of the method results from the fact that it is carried out in closed containers. Therefore, the diffusion of poisonous gas due to the decay of organic matter into the environment is prevented, thereby improving the working conditions of leather tanning treatment places.

Moreover, the proposed method greatly alleviates the problems of waste disposal and/or neutralization, saving energy and materials used, especially for tanning and dyeing. It must also be emphasized that the method described here can also be carried out without leather washing.

Figure 5a shows another embodiment of the apparatus in which the same steps are carried out using more process vessels, as in the apparatus shown in Figure 4a. There are 4 containers 4a, 4b, 4c and 4d arranged in a row for the watering, liming, pickling and tanning steps which are accompanied by dyeing and possibly fatliquoring.

The tanks containing the solutions for these steps and the subsequent washings are indicated with the same numbers as in Figure 4a, and are equipped with the same types of valves and pumps as described above (not shown).

In this case, the frame 2 supporting the unfolded leather pieces is for example mounted on a carrier 28 integral with a conveying device 29 which feeds said carrier 28 into and out of the containers 4a, 4b, 4c and 4d. These conveying devices 29 comprise, for example, carriages 30 driven by electric means (not shown), which move along rail members 31 integral with a fixed frame 32 of the device. Thus, in each container, the predetermined steps of the treatment of the hide and possibly the washing of said hide are carried out. Preferably, the hides are washed in respective auxiliary containers 114a, 114b (see Figure 6).

More precisely, after immersion in the container 4a, the leather is removed therefrom and sent to the auxiliary container 114a, where the leather is washed with the liquid solution in the storage tank 30a. The liming step is carried out in the container 4b, followed by washing in the associated auxiliary container 114b.

The method carried out, ie washing the leather in the auxiliary container, avoids cleaning of the containers 4a, 4b after the washing operations of immersion and liming, respectively.

The apparatus shown in Figure 5b performs the processing steps described in Figure 4b. In containers 4a, 4b, 4c and 4d, the leather is soaked in water, limed, pickled, pretanned, tanned, finally dyed and fatliquored.

The vessels in which these steps are carried out are designated with the same reference numbers as in Figure 4b. In this case, the washing after the soaking, liming and pretanning steps can be carried out in associated auxiliary tanks, as in the case shown in FIG. 6 .

Obviously, if leather treatment requires many operations different from those of the two illustrative embodiments (Figures 4a, 5a and 4b, 5b), the equipment will be changed accordingly, while retaining all the advantages of the invention.

In the embodiment shown in Figures 5a, 5b, 6, the liquid solutions drained from the respective vessels may also be sent to a common drain header.

The feature of the preferred embodiment of the present invention has following technical aspect:

- container 4 remains fixed;

- the leather pieces are unfolded and spaced by this;

- the treatment is carried out in a container which is closed and kept under negative pressure before the liquid solution is introduced into it;

- Turbulence of the liquid solution, which produces a massaging effect on the leather.

According to a variant of the method, the container 4 (or container 4a, 4b, 4c, 4d) can be rotated along the transverse and/or longitudinal axis in order to keep the leather pieces and the liquid solution used during the treatment step or the subsequent washing step relative motion between them.

Preferably, the liquid solution contained in the tanks 111a, 111b substantially reduces and/or neutralizes any volatilization that occurs within the container 4 (or containers 4a, 4b, 4c, 4d, 4e, 4f) during leather treatment. Sexual compounds.

To this end, further containers 111 can be installed in parallel, each containing a liquid solution capable of substantially reducing and/or neutralizing at least one predetermined volatile compound. It is possible that the control unit 14 acts on suitable equipment, such as electric valves, connected to these tanks in order to feed the line 110 of one or more liquid solutions arranged in line. This depends on the relevant processing step carried out in vessel 4, and the kind of volatile compounds produced in this step.

In the case of more containers, each line 110 connected to the evacuation device 11 is connected to a storage tank 111 which acts as described above. Each feed tank may be provided with means for mixing the liquid solutions contained therein, these means not being shown as they are within the purview of those skilled in the art.

Fig. 7 represents another embodiment of this equipment, and wherein numeral 201,202,203,204 represents that soaking, liming, pickling and tanning use the feed tank of the liquid solution that soaking is housed respectively. Numbers 212a, 212b, 212c, 212d designate corresponding heat exchangers (controlled by control unit 14 via connections S1, S2, S3, S4). Reference numerals 216a, 216b, 216c, 216d designate corresponding feed pumps, which are also operated by the control unit 14 via the connections P1, P2, P3 and P4.

In this case, the spraying device, ie the grid 9, can be communicated with the outside world (normal operating conditions of the container 4) through the associated electric valve 250 operated by the control unit.

As an alternative, the spraying device 9 may be connected to one or the other of a series of auxiliary supply tanks 300a, 300b, 300c, 300d (e.g. 4 tanks, but the number can be greater or less than 4).

Each auxiliary feed tank contains a suitable substance, pure or suitably diluted, for use with the liquid solution in the feed tanks 212a, 212b, 212c, 212d during the respective step of the method.

This structure defines advantageous conditions in that it allows this substance to be mixed with each involved liquid solution in predetermined percentages and/or weights in order to carry out the process steps in the desired manner.

In order to put this possibility into practice, the control unit 14 cuts off the connection between the container 4 and the outside world (via the electric valve 250), connects the container 4 to the predetermined auxiliary supply tank, and maintains this connection for a short time. The negative pressure conditions in container 4 cause material from the auxiliary feed tank to flow into the container. Material flow can be determined with pump 270 (which is not shown) and can be measured with a suitable meter (also not shown).

By using a grid 9 that sprays the substance into the container, it is possible to rapidly mix the sprayed substance with the liquid solution 5 already inside the container.

As another alternative, these substances may be introduced into the container simultaneously with the introduction of the liquid solution 5 or before the introduction of the liquid solution. Moreover, these substances can also be fed into the container in other ways without the aid of the grid 9 . These methods will be apparent to those skilled in the art.

When at least one substance (or its dilution) has completely entered the container 4, the connection between the container and the auxiliary supply tank is severed, while the connection between the container and the environment is restored. In the embodiment shown in Figure 7, the auxiliary feed tank is connected to the vessel 4 where the various process steps are carried out.

Preferably, the auxiliary feed tank is connectable to the containers 4a, 4b, 4c, 4d of different configurations in Figures 5a and 6 and to the containers 4a, 4b, 4c, 4d, 4e, 4f shown in Figure 5b, which The loaded material is used in a manner similar to that just described.

FIG. 8 relates to a functional structural feature of the container 4 . In detail, there is a line 600 connecting the bottom of the container 4 with its middle 601 . More precisely, this middle part is just below the free surface 602 of the liquid solution 5 in the container.

A pump is installed in line and operated by the control unit 14 to draw the fluid solution from the container 4 at 601 and send the liquid solution back to the bottom. This encourages continuous remixing of the liquid material and prevents settling of the solid material. The content of what has just been said, makes the liquid substance have a very uniform result in all parts.

This functional structural property can be used for each container 4a, 4b, 4c, 4d of the embodiment of Figures 5a and 6, and can be used for each container 4a, 4b, 4c, 4d, 4e of the embodiment shown in Figure 5b , 4f.

Referring to Figures 9a, 9b, numeral 500 denotes a vapor recovery unit. Preferably, more recovery units are provided, for example a number at least equal to the number of process steps carried out in the vessel 4 . Figures 9a, 9b show only one recovery unit, since the other recovery units can be operated in exactly the same way.

The recovery unit comprises an electric valve 404 installed in a line 450 connecting the evacuation device 11 with the interior of the container. Two pipelines 460 and 470 are branched from the pipeline 450, namely the first pipeline and the second pipeline, on which a three-way electric valve 401 and a two-way electric valve 402 are installed respectively. These lines pass through the closure cover of the condensation container 400, under the cover, there is a partition 480 placed obliquely on the upper part of the container. The opening of the first pipe 460 is below the inclined partition, and the opening of the second pipe 470 is above the partition. The bottom of the container is connected to the bottom of the container 4 through a pipeline 490 with an electric valve 403 . The electric valves 401 , 402 , 403 , 404 just mentioned are all operated by the control unit 14 .

Under the operating conditions shown in FIG. 9 a , the stream H drawn from the container 4 with the evacuation device 11 passes through the container 400 . This stream is essentially formed by a mixture of air (introduced into the container by injection means 9 ) and vapor formed from liquid solution 5 . This mixture expands in the container and cools, causing more vapor to condense. The liquid thus obtained is collected at the bottom of the container, the level of which gradually rises. When a certain liquid level is reached, the sensor 405 detects it and sends a signal to the control unit 14, which determines the operating conditions of Fig. 9b by operating the above-mentioned electric valve.

In this condition, the vessel 400 is bypassed because the valve 404 is open, while the valve 401 communicates the interior of the vessel with the outside world, and the second line 470 is shut off with the shut-off valve 402 .

Since the container 4 is under negative pressure, the liquid flow K flows from the container to the container 4 . A suitable sensor (not shown) detects the minimum liquid level in the container 500 . The control unit thus changes the operating conditions of the unit 500, restoring the conditions of Figure 9a.

What has just been said is a very advantageous feature, since in this way most of the vaporized liquid can be recovered without being carried over to the evacuation device 11 .

The partition 480 forms a partition between the air-steam mixture feed zone (first line 460) and the air evacuation zone (second line 470) so that negligible amounts of steam are delivered to the evacuation device anyway.

Due to the use of different liquid solutions 5 (for the above-mentioned different process steps), the relevant recovery unit 500 is also equipped with a gas collector 410 communicating with all recovery units, one side of which is connected to the top of the container, and the other side is passed through An associated line 490a is connected to the bottom of the vessel. For each container 4a, 4b, 4c, 4d (shown in Figures 5a and 6) and 4a, 4b, 4c, 4d, 4e, 4f (shown in Figure 5b), there may be a recovery unit 500 just described.

According to an interesting variant of the method, the favorable results obtained by the combined action of the vacuum and the turbulent movement on the leather can be further increased and improved by ultrasonic treatment of the liquid solution. This can be done with a suitable sonotrode (not shown) of known type, which is connected to the container and controlled by the control unit 14 .

It should be understood that the above is purely a non-limiting example, therefore, possible functional modifications of the process steps are still within the protection scope of an invention required by the appended claims.

Similar observations can be considered with reference to the various devices that make up the plant, where measuring instruments can be used to measure the flow in and out of each container or feed tank for each step.

Claims (52)

1. A method of processing leather, etc., characterized in that it comprises: installing unfolded leather pieces (1) to be treated in containers (4) at intervals from each other; Described container (4), so that carry out each step of leather tanning treatment, after each step is finished, described liquid solution is discharged from container; Make described container interior maintain negative pressure at least in every single step process ; In each step, a relative movement is generated between the liquid solution and the leather sheet, so as to intensify the effect of the liquid solution on the leather sheet. 2. A method for treating leather etc., characterized in that it comprises: installing the unfolded leather pieces (1) to be treated at intervals in a first container (4a); feeding a liquid solution into said container (4a) , so as to carry out the leather tanning treatment step; during the step, the inside of the container is maintained at negative pressure; during the step, relative motion is generated between the liquid solution and the leather sheet, so that Strengthening the effect of the liquid solution on the leather sheet; discharging the liquid solution from the first container; taking out the leather sheet from the first container; repeating the above operations in another container, for other steps in the leather tanning process. 3. A method according to claim 1, characterized in that a negative pressure is created inside the container before the liquid solution for the corresponding leather treatment step is introduced thereinto. 4. 2. A method according to claim 2, characterized in that a negative pressure is created inside each of said containers where the leather treatment step is carried out, before the corresponding liquid solution is introduced into the container. 5. The method according to claim 1 or 3, characterized in that it comprises: sending the first liquid solution for immersing said leather into said container (4); turbulent flow of said liquid solution; discharging said solution from the container; sending a second liquid solution for said leather liming into said container (4); during said liming step, making said liquid solution turbulent; discharging said solution from said container; sending a third liquid solution for said leather pickling into said container (4); In the steps, said liquid solution is turbulent; said solution is discharged from the container; a fourth liquid solution for simultaneous tanning and dyeing of said leather is fed into said container (4); In the tanning and dyeing steps of the method, the liquid solution is allowed to flow; the solution is discharged from the container; finally, the unfolded leather piece is removed from the container. 6. The method according to claim 5, characterized in that, between said first, second, third and fourth liquid solutions, when at least one liquid solution is sent into said first container, simultaneously The introduction of a pure or diluted substance intended to be co-operated with the relevant liquid solution in order to carry out the corresponding steps of the same method. 7. The method according to claim 2 or 4, characterized in that it comprises: sending the first liquid solution for immersing said leather into said first container (4a); in said immersing step, using The liquid solution is turbulent; the solution is discharged from the first container; the leather piece is taken out from the first container (4a); the unfolded leather piece is put into the second container with the method of being spaced apart from each other (4b), the container is closed; the second liquid solution for liming the leather is sent into the second container (4b); in the liming step, the maintaining negative pressure; during said liming step, turbulent flow of said liquid solution; discharging said solution from the second container; taking out the leather pieces from the second container (4b); The unfolded leather pieces are placed in a third container (4c) spaced apart from each other, which is closed; a third liquid solution for pickling said leather is placed in said third container (4c), The container is closed; during the pickling step, maintain negative pressure in the third container; during the pickling step, make the liquid solution turbulent; discharge the taking out the leather pieces from the third container (4c); putting said unfolded leather pieces into a fourth container (4d) spaced apart from each other; the container is closed; it will be used for at least tanning and The fourth liquid solution for dyeing the leather is sent into the fourth container (4d); during the tanning and dyeing step, maintaining a negative pressure in the fourth container; during the tanning and dyeing step , causing said liquid solution to turbulence; discharging said fourth solution from a fourth container; and removing a piece of leather therefrom. 8. A method according to claim 7, wherein at least one pure or diluted Substances fed in, intended to co-operate with the associated liquid solution, in order to carry out the corresponding steps of the same method. 9. The method according to claim 1 or 3, characterized in that it comprises: sending a first liquid solution for immersing said leather into said container (4); turbulent flow of the solution; discharging said solution from the container; feeding a second liquid solution for liming leather into said container; during said liming step, turbulent flow of said liquid solution ; discharge said solution from the container; send the third liquid solution for pickling said leather into said container (4); in said pickling step, make said liquid solution turbulence; discharge said solution from the container; send a fourth liquid solution for pre-tanning said leather into said container (4); during said pre-tanning step, make said turbulent flow of the liquid solution; discharging said solution from the container; sending a fifth liquid solution for tanning said leather into said container (4); during said tanning step, causing said turbulent flow of the liquid solution; discharge said solution from the container; send at least a sixth liquid solution for dyeing said leather into said container (4); during said dyeing step, make said turbulent flow of the sixth liquid solution; draining said solution from the container; finally, removing the unfolded piece of leather from the container. 10. The method according to claim 9, characterized in that, between said first, second, third, fourth, fifth and sixth liquid solutions, at least one liquid solution is sent to said first A container into which simultaneously at least one substance, pure or diluted, is intended to co-operate with an associated liquid solution in order to carry out at least one associated step of the same method. 11. The method according to claim 2 or 4, characterized in that it comprises: sending the first liquid solution for immersing said leather into said first container (4a); in said immersing step, using Turbulent flow of said liquid solution; discharging said solution from the first container; taking out the leather pieces from the first container (4a); sending said unfolded leather pieces into the second container in a spaced manner (4b), the container is closed; the second liquid solution for liming the leather is sent into the second container (4b); during the liming step, the negative press; during said liming step, turbulent flow of said second liquid solution; discharge said second liquid solution from second container; take out leather from second container (4b) said unfolded leather pieces are put into a third container (4c) at intervals from each other, and the container is closed; a third liquid solution for pickling said leather is sent into said first In the three containers (4c); in the pickling step, keep the negative pressure in the third container; in the pickling step, make the liquid solution turbulent; discharge from the third container said solution; take out the leather pieces from the third container (4c); put said unfolded leather pieces into a fourth container (4d) spaced apart from each other; this container is closed; will be used for pre-tanning The fourth liquid solution of the leather is sent into the fourth container (4d); in the pre-tanning step, keep negative pressure in the fourth container; in the pre-tanning step, make the turbulent flow of the fourth liquid solution; discharge the fourth solution from the fourth container; take out the leather pieces from the fourth container (4d); put the unfolded leather pieces into the first In the fifth container (4e), the container is closed; the fifth liquid solution for tanning the leather is sent into the fifth container (4e); during the tanning step, the fifth container maintaining a negative pressure inside; during the tanning step, making the fifth liquid solution turbulent; discharging the fifth solution from the fifth container; taking out the leather piece from the fifth container (4e); Said unfolded leather pieces are put into a sixth container (4f) in a spaced manner from each other, and the container is closed; the sixth liquid solution for dyeing said leather is sent into said sixth container (4e) ); in the dyeing step, keep negative pressure in the sixth container; in the dyeing step, make the sixth liquid solution turbulent; discharge from the sixth container said solution; remove the leather piece from it. 12. The method according to claim 11, characterized in that, when said relevant liquid solution is sent into at least one of said first, second, third, fourth, fifth and sixth containers, at least one Pure or diluted substances are introduced, intended to be co-operated with the relevant liquid solutions in order to carry out the corresponding steps of the same method. 13. Method according to claim 5 or 9, characterized in that there is an intermediate step of leather washing before the liming step is completed and before the pickling treatment. 14. A method according to claim 5 or 9, characterized in that there is a leather washing step after the immersion step is completed and before the liming step. 15. A method according to claim 9, characterized in that after the pretanning step and before the tanning step there is an intermediate step of leather washing. 16. Method according to claim 7 or 11, characterized in that, after the soaking step, there is an intermediate step of leather washing in said first container (4a). 17. Method according to claim 7 or 11, characterized in that, after the liming step, there is an intermediate step of leather washing in said second container (4b). 18. Method according to claim 7, characterized in that the leather is washed after the pretanning step. 19. 2. A method according to claim 1 or 2, characterized in that the relative movement between the liquid solution and said piece of leather is obtained by injecting a stream of air into said liquid solution while the container is held still. 20. A method according to claim 1 or 2, characterized in that the relative movement between the liquid solution and the leather sheet is obtained by leaving the container unchanged, connecting its bottom to the outside, thus generating an air flow, the air flow through the liquid solution. twenty one. A method according to claim 1 or 2, characterized in that the relative movement between the liquid solution and the leather sheet is obtained by continuous flow from the container 4 at a liquid level close to the upper liquid level 602 of the container. The liquid solution is withdrawn and fed again at the bottom of the container. twenty two. A method according to any one of the preceding claims, characterized in that said leather sheets are spread out on respective open support devices. twenty three. 22. The method of claim 22, wherein said leather pieces are mounted vertically. twenty four. The method according to claim 22, characterized in that said leather sheet is installed horizontally. 25． The method according to claim 22, characterized in that said leather sheet is mounted obliquely to a vertical plane. 26． The method according to claim 7 or 11, characterized in that, after the soaking step is completed, the leather piece is taken out from the container in which the soaking step is performed, and sent into the auxiliary container 114a for washing. 27． A method according to claim 7 or 11, characterized in that, after the liming step is completed, the leather pieces are removed from the container in which the liming step was carried out, and placed in an auxiliary container 114b for washing. 28． The method according to claim 11, characterized in that, after the pretanning step is completed, the leather pieces are removed from the container in which the pretanning step was carried out, and placed in an auxiliary container for washing. 29． A method according to claim 1 or 3 or 5 or 9, characterized in that, in each treatment step, the liquid solution associated with each step is treated with ultrasound. 30． 2. A method according to claim 2 or 4 or 7 or 11, characterized in that, in each treatment step, the liquid solution associated with each step is treated with ultrasound. 31． Equipment for the treatment of leather etc., characterized in that it comprises: a closed container (4); a plurality of supports, which can be placed in and taken out of said container, on which supports the corresponding unfolded leather sheet (1) is fixed, These racks are placed in said containers in such a way that said leather pieces are spaced apart from each other; a first series of tanks (12) containing predetermined liquid solutions for the respective leather treatment steps; each of said Switchgear and control equipment (14, 16, 18) of the storage tank connected to the container in order to feed into it the relevant liquid solution for the respective leather treatment step; keeping the interior of said container under negative pressure at least while the leather treatment step is carried out An evacuation device (11); a device for generating relative motion between the liquid solution and the leather sheet, so as to strengthen the effect of the liquid solution on the leather. 32． Plant according to claim 31, characterized in that it comprises a second series of tanks (23) connected to the container via switchgear and control equipment (14, 21, 25) in order to receive from said Liquid solution discharged from a container. 33． Apparatus according to claim 31, characterized in that it comprises a series of auxiliary storage tanks (300a, 300b, 300c, 300d) connected to the container by means of switchgear and control equipment, in order to feed a pure or diluted substance into Said container, said substance is used together with a corresponding liquid substance to carry out at least one leather treatment process step. 34． Equipment for the treatment of leather etc., characterized in that it comprises a number of closed containers (4a, 4b, 4c, 4d) in which predetermined leather treatment steps are carried out; and taken out of the container on which the corresponding unfolded leather pieces (1) are fixed, these shelves are placed in said container in such a way that the leather pieces are kept spaced apart; containing the predetermined liquid for the corresponding leather treatment step a first series of storage tanks (12) for solutions; switchgear and control equipment for connecting each said storage tank with the associated container, so as to feed into it the relevant liquid solution for the corresponding leather treatment step; enabling each an evacuation device (11) for maintaining a negative pressure inside said containers at least during the associated leather treatment step; in each of said containers a relative movement is created between the corresponding liquid solution and said leather pieces equipment in order to intensify the action of said liquid solution on leather. 35． 26. Apparatus according to claim 26, characterized in that the second series of storage tanks are connected to the respective containers through switchgear and control means to receive the liquid solution discharged from said containers after completion of the respective steps. 36． Apparatus according to claim 34, characterized in that, for each container (4a, 4b, 4c, 4d), it comprises an associated auxiliary supply tank connected to the corresponding container via switchgear and control equipment for At least one substance, pure or diluted, is fed into said associated container in order to carry out the associated leather treatment process step together with the liquid solution fed into the container. 37． Apparatus according to claim 31, characterized in that said means for holding the container (4) stationary and for generating relative motion between the liquid solution and the leather sheet comprise injectors (10) which send air jets into the container. In liquid solution in a container. 38． Apparatus according to claim 34, characterized in that the means for holding each of said containers stationary and for generating relative motion between the liquid solution in each container and the piece of leather comprises an injector (10) which injects air The jet stream is fed into the liquid solution. 39． An apparatus according to claim 31, characterized in that at least one storage tank (111a, 111b) for significantly reducing and/or neutralizing volatile compounds generated during leather treatment is connected to said evacuation device (11 ) and the pipeline (110) of the container (4). 40． An apparatus according to claim 34, characterized in that at least one storage tank (111a, 111b) for substantially reducing and/or neutralizing volatile compounds generated during leather treatment is connected to said evacuation device (11 ) and the pipeline (110) of the container. 41． According to the equipment of claim 31, it is characterized in that, it also comprises other storage tanks (30), and they are connected with described container by switchgear and control equipment, so that after corresponding step is finished, send into the tank (30) that is used for washing leather. The liquid solution is suitable, and the suitable liquid solution is subsequently discharged from the container. 42． Apparatus according to claim 34, characterized in that it comprises further storage tanks (30), each of which can be connected to a corresponding container by means of switchgear and control equipment, so as to be sent for washing after the corresponding step is completed. A suitable liquid solution of the leather and subsequent discharge of the suitable liquid solution from the container. 43． Apparatus according to claim 34, characterized in that it comprises auxiliary containers (114), each of which can be connected via switchgear and control means to a corresponding tank containing a predetermined liquid solution, which solution can be introduced and subsequently removed from Said auxiliary container is discharged in order to wash the leather pieces fed therein after completion of the processing steps in the corresponding container. 44． Apparatus according to claim 31, characterized in that it comprises a line (600) communicating the bottom of said container (4) with the middle (601) of the same container, said middle (601) being just within the container of the liquid solution ( 5) Below the free liquid surface (602), the pipeline has a pump device (603) for continuously transporting the liquid solution from the middle (601) to the bottom of the container. 45． An apparatus according to claim 34, characterized in that, for each container (4a, 4b, 4c, 4d), it comprises a line (600) communicating the bottom of said container (4) with the middle of the same container, The middle part (601) is just below the free liquid surface (602) of the liquid solution (5) in the container, and the pipeline has a pump device (603) for pumping the liquid solution from the middle part (601) ) is continuously delivered to the bottom of the container. 46． Apparatus according to claim 31 or 34, characterized in that for each vessel (4, 4a, 4b, 4c, 4d) it comprises at least one vapor recovery unit (500) comprising a closed condensation vessel (400); a first switchgear (401, 404, 402) operated by the control unit (14) for connecting said vessel (400) in series with a pipeline (450) which makes said vessel (400) is in communication with the described evacuation equipment (11); the sensing equipment (405) used for detecting the liquid level in the container (400), these sensing equipments and the described control unit (14) jointly operate the The first switchgear and the second switchgear (403) described above, so as to cut off the passage between the container (400) and the pipeline (450), make the inside of the container (400) communicate with the outside, and connect the container (400) with the outside The containers (4) are communicated so that condensed liquid can be transferred from the container (400) to the container (4). 47． Apparatus according to claim 46, characterized in that there is an inclined partition (480) in the container (400), the open end of the first pipeline (460) being below said partition, for feeding from said container ( 4) The air-steam mixture flow (H) is sent into the container (500), and the open end of the second pipeline (470) is connected to the evacuation device (11). 48． 38. Apparatus according to claim 37 or 38, characterized in that said leather sheets are mounted vertically. 49． 38. Apparatus according to claim 37 or 38, characterized in that said leather sheets are mounted horizontally. 50． 38. Apparatus according to claim 37 or 38, characterized in that said leather sheet is mounted obliquely in any manner. 51． 31. An apparatus according to claim 31 or 37 or 30 or 32, characterized in that it comprises a sonotrode connected to the container (4) for treating each liquid solution with an ultrasonic beam. 52． 34. Apparatus according to claim 34 or 38 or 40, characterized in that it comprises a number of sonotrodes, one associated with each container, for treating each liquid solution with an ultrasonic beam.

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