WO2002068135A1

WO2002068135A1 - Process for the treatment of organic materials

Info

Publication number: WO2002068135A1
Application number: PCT/IT2002/000116
Authority: WO
Inventors: Lucio Colla
Original assignee: Newster S.R.L.
Priority date: 2001-02-28
Filing date: 2002-02-27
Publication date: 2002-09-06
Also published as: ITRN20010016A1

Abstract

A process for the treatment of organic materials, in particular useful for the disposal of so-called 'animal meal', comprises at least the following steps: mixing the organic material with a first plastic material; heating the mass obtained, so as to obtain a liquid mixture with uniform characteristics; gradual solidification of the mixture in the form of granules. At the end of the process, during which temperatures suitable for the thermal destruction of the proteins are reached, the material is in a form which can be packaged for protection against atmospheric agents and can be stored in a waste disposal site, pending reuse as an alternative fuel.

Description

Process for the treatment of organic materials

Description Technical field

The present invention relates to a process for the treatment of organic materials, which is particularly effective for the disposal of waste containing animal proteins. Background art

It is nowadays customary - and plays a precise part in management of the sector for production of meat for human consumption - to recover and collect at least part of the waste from slaughter-houses and transport it to special plants for processing in order to produce, in accordance with the existing national and international regulations, so-called "animal meal", the whole operating cycle being performed in such a way as to fully satisfy and guarantee hygiene and sanitary standards.

The spread of transmittable spongiform encephalopathy, and in particular the infective form known as Bovine Spongiform Encephalopathy (BSE) - also known as "mad cow disease" - has led the relevant authorities, both at a European Community level and in national governments, to ban the use of fodder containing proteins derived from animal tissues for feeding herbivorous animals as well as the use of processed animal proteins for feeding livestock reared for food production.

In order to prevent the spread of the disease via this channel it is of fundamental importance to ensure the elimination, from the animal food chain, of all the material containing animal proteins derived from the processing of slaughter-house waste and hence also animal meal. The methods of highlighting with permanent dyes which are currently used are obviously not sufficient to ensure the exclusion of this fodder from the animal chain since the control and prevention of fraud is increasingly difficult, as demonstrated by the recent sequester of products and processing plants by the authorities.

The ban on animal meal has, however, caused serious organizational problems, both with regard to the temporary storage of meal derived from low-risk materials and with regard to the thermal destruction of meal derived from high-risk materials.

As regards the former, the storage depots have a limited capacity and it is possible that they, too, may be subject to a permanent ban. Since the current disposal capacity is insufficient for the quantities of meal which need to be destroyed now, the lack of available resources for dealing with the potential problem of having to destroy low-risk meal as well is obvious . As regards the thermal destruction of animal meal resulting from high-risk materials, the sole disposal systems which can be currently used in Italy consist of urban waste processing plants and cement factories. These facilities, however, would also require modifications since the fumes produced by this type of waste contain ash with a very low softening point

(well below 1000 °C) which becomes a agmatic mass which is deposited on the tube bundles of the recovery boilers, impairing operation thereof. Moreover, despite the fact that animal meal has a high calorific power, which could make it of potential interest for use as an alternative fuel, in Italy there are no thermoelectric power stations destined for this purpose. Disclosure of the invention

The object of the present invention is therefore to eliminate the drawbacks mentioned above.

The invention, as it is characterized by the claims, achieves the object by means of a process in which the organic material to be eliminated is mixed and melted with plastic material and is then rendered inert by means of encapsulation inside the latter during the solidification process.

The main advantage obtained by means of the present invention consists essentially in the fact that this organic waste containing animal protein is first treated so as to favour the thermal destruction of the proteins and then definitively eliminated from the food chain by means of encapsulation in granules of plastic material.

Moreover, mixing with reject plastic material allows the simultaneous destruction of huge quantities of plastic waste as well as optimisation of the calorific power which can be obtained during treatment and the production of fuel derived from waste of uniform quality- After the product has been rendered biologically and chemically inert using this process, it may be definitively or temporarily stored in so-called "2B" waste disposal sites which are widespread in Italy. Finally it may be suitable for packaging in plastic film which is resistant to the action of atmospheric agents, thus ensuring the possibility of its reuse as an alternative fuel in specially designed thermoelectric power stations, owing to its high calorific power.

Further advantages and characteristics of the invention will emerge more clearly from the detailed description which follows. Detailed description of the preferred embodiment (s)

The invention relates to a process for the treatment of organic materials. It is suitable in particular for the elimination of waste containing animal proteins, such as for example so-called animal meal derived from slaughter-house waste, to which reference is made mainly in the description below.

The process for the treatment of the organic materials in question, although it can be modified or supplemented with the addition of further steps, must comprise at least one step involving mixing of the organic material with a first plastic material, a step involving heating of the mass obtained, so as to obtain a liquid mass with uniform characteristics, and a step involving gradual solidification of the mixture in the form of granules.

These steps may be advantageously preceded by a preliminary step, in which the organic material and the first plastic material are collected in separate tanks comprising automatic extraction and weighing systems for metering the quantities thereof to be mixed.

Although the mixing and heating of the mass formed by the organic material and by the first plastic material may be performed simultaneously it is preferable that firstly the organic material and the first plastic material should undergo partial heating in separate tanks, thereby resulting in a process of heating of the mass divided into several successive stages. Thus, during a first heating stage in which the temperature reaches and exceeds 100 °C, it is envisaged eliminating the moisture present in the mass, increasing the temperature thereof using mechanical friction operations and/or thermal heating operations by means of contact. For this purpose, during the first heating stage, the mass is supplemented with a second plastic material having a high melting point able to increase the temperature thereof by means of friction, performing the function of a temperature catalyst. If the organic material is already dry, since it has already undergone previous processing, this heating stage could be eliminated.

During a second heating stage it is envisaged performing the thermal destruction of the proteins which occurs at temperatures of about 200°C. At this point it envisaged melting the first plastic material so as to form a "wetting" film lining the organic material and enveloping the individual granules of meal.

From this point onwards, the gradual solidification of the mixture in the form of granules is performed by means of the controlled introduction of a liquid, consisting of water and/or a suitable chemical solution. Whereas the temperature previously reached is generally maintained, in order to favour completion of thermal destruction of the proteins, each introduction of liquid causes an instantaneous and localised reduction in temperature sufficient to determine partial granulation of the mixture during evaporation of the liquid. When granulation of the mixture is complete and the meal granules are incorporated inside the plastic material, a step involving rapid discharge into a pneumatic conveying system, with a sudden drop in the temperature and corresponding completion of the granulation, is started.

Finally, the granulated material is packaged inside plastic packaging for protection against atmospheric agents and stored in the waste disposal site. With this type of procedure it is therefore possible to neutralise the notorious animal meal, eliminating it from the food chain, but at the same time also store it suitably pending the construction also in Italy of thermoelectric power stations designed to use it as an alternative fuel. During the whole process, it is envisaged capturing and treating the gaseous effluent so as to avoid any discharge of pollutants into the external environment .

The invention thus conceived is subject to numerous modifications and variants, all of which fall within the scope of the inventive idea. Moreover, all the details may be replaced by technically equivalent elements.

In practice, modifications and/or improvements are obviously possible, nevertheless falling within the scope of the following claims.

Claims

1. Process for the treatment of organic materials, characterized in that it comprises at least the following steps: mixing the organic material with a first plastic material;

- heating the mass obtained so as to obtain a liquid mass with uniform characteristics;

- gradual solidification of the mixture in the form of granules.

2. Process according to Claim 1, characterized in that it comprises a preliminary step in which the organic material and the first plastic material are collected in separate tanks so as to meter the quantities thereof which are to be mixed.

3. Process according to Claim 2, characterized in that the tanks comprise automatic extraction and weighing systems.

4. Process according to Claim 1, characterized in that mixing and heating of the mass formed by the organic material and by the first plastic material are performed simultaneously.

5. Process according to Claim 1, characterized in that the heating of the mass obtained is performed in successive stages.

6. Process according to Claim 5, characterized in that the first heating stage envisages elimination of the moisture present in the mass, increasing the temperature thereof by means of mechanical friction operations and/or thermal heating operations with contact .

7. Process according to Claim 6, characterized in that, during the first heating stage, the mass is supplemented with a second plastic material having a high melting point and able to increase the temperature thereof by means of friction.

8. Process according to Claim 5, characterized in that the second heating stage envisages the thermal destruction of the proteins.

9. Process according to Claim 5, characterized in that the second heating stage envisages the melting of the first plastic material so as to form a film lining the organic material.

10. Process according to Claim 1, characterized in that the gradual solidification of the mixture in the form of granules is performed by means of controlled introduction of a liquid which causes a reduction in the temperature sufficient to cause granulation of the mixture during evaporation of the liquid.

11. Process according to Claim 10, characterized in that the liquid is a chemical solution.

12. Process according to Claim 10, characterized in that the liquid is water.

13. Process according to Claim 1, characterized in that it comprises a successive step involving rapid discharge into a pneumatic conveying system, with a sudden drop in temperature and corresponding completion of granulation.

14. Process according to Claim 1, characterized in that it comprises a final packaging step for protection against atmospheric agents and storage in a waste disposal site.

15. Process according to Claim 1, characterized in that it envisages capturing and treating the gaseous effluent so as to prevent any discharge of pollutants into the external environment.

16. Process according to the preceding claims and in accordance with that described for the objects mentioned.