METHOD FOR MINUTELY CRUSHING ASBESTOS CONTAINING WASTE IN CONDITION OF ENVIRONMENTAL SAFETY

Abstract: Method for crushing asbestos containing waste, characterised in that the material to be crushed, optionally sealed in containers of plastics material, is subjected to the action of a ball mill - wherein the balls are made in any suitable material - operating under inert fluid, to attain a product with size and granulometric distribution suitable to subsequent aggregating or transforming steps aimed at the disposal thereof, and in that the optional container is extracted substantially uncrushed at the end of the crushing cycle. This method is environmentally safe and the obtained minutely crushed material is suitable to the subsequent transforming or aggregating treatments aimed at the disposal of said waste.

Description: METHOD FOR MINUTELY CRUSHING ASBESTOS CONTAINING WASTE IN CONDITION OF ENVIRONMENTAL SAFETY DESCRIPTION The present invention relates to the field of the disposal of asbestos containing waste (ACW) . As it is known, since about a century the art has been aware of asbestos, the latter being increasingly used starting from around 1940 in the industrial and service fields for the formulation of over three thousand products. However, owing to its confirmed carcinogenicity, a need has emerged for the disposal, in condition of environmental safety, of the waste containing it which has accumulated in the most varied forms and conservation states. In this regard, several processes suitable to make the ACW harmless, aimed at reducing or totally eliminating the harmfulness thereof, do exist. These processes provide, on the one hand, the ACW conditioning in matrices of different nature (e.g., concrete, resins), and on the other hand the direct intervention on the fibre structure of the asbestos mineral. In both cases, the material to be made harmless should have a minute granulometry. The prior art confronted the problem of the attainment of a fine granulometry of the ACW using grinding techniques (fast-rotating mills provided with knives; vibrating mills, planetary and attrition mills provided with grinding bodies) . However, these techniques failed to provide a ground material suitable to the subsequent ACW aggregating or transforming steps. In particular, the ACW not aggregated to concrete, like, e.g., the Eternit plates, due to the crystalline structure thereof appear to be difficult to crush. The method according to the present invention allows to overcome all the hereto mentioned drawbacks and to satisfy all the highlighted needs, further providing other advantages which will be made apparent hereinafter. In fact, subject of the present invention is a method for crushing asbestos containing waste, characterised in that the material to be crushed, optionally sealed in containers of plastics material, is subjected to the action of a ball mill operating under inert fluid, to obtain a product with sizes and granulometric distribution suitable to subsequent aggregating or transforming steps aimed at the disposal thereof, and in that the optional container is extracted substantially uncrushed at the end of the crushing cycle. The ball mill may be a tumbling mill. The balls of the mill may be made in any suitable material, like, e.g., alumina, and in particular 90% alumina. In a particular and preferred embodiment, the inert fluid under which the mill operates may be water. The granulometry of the material ' crushed with the method of the present invention ranges from 5 to 500 μm. Among the main advantages associated to the use of the method according to the invention, the following may be mentioned: since the operations are carried out under inert fluid, the danger of environmental pollution during the crushing process is eliminated; the granulometric distribution of the particles attained with the method according to the present invention eases the transforming or the aggregating of the asbestos containing waste; and - since the plastics material of the container is not crushed, the absence thereof results in a greater effectiveness in the subsequent treatments of the asbestos containing wastes or ACW. So far, a general description of the present -invention has been provided. With the aid of the following example, hereinafter a specific embodiment thereof will be provided, aimed at making better understood the objects, features, advantages and operation modes thereof. EXAMPLE 1 280 kg ACW with the following composition: - pure fibre asbestos, like rock wool 50 kg Eternit plates 230 kg are subjected to the crushing method according to the present invention. A tumbling mill with the following characteristics: diameter 1 m length 1 m inside capacity 785 litres is used. This mill is filled for one half of the volume thereof with Alubit™ balls with a diameter ranging from 35 to 5 mm, and water-filled for the other half. The mill is subjected to a 30 rpm rotation with a 5.5 KWh motor. After 4h a sludge of asbestos particles with dimensions ranging from 5 to 500 μm is attained, having the following granulometric distribution: 55 % > 250 μm 28 % > 125 μm - 6 % > 63 μm 6 % > 38 μm 5 % < 38 μm Had the same material been subjected to the action of traditional grinding devices, like, e.g., fast- rotating mills provided with knives, instead of a granulate a flocculate product, unsuitable to the subsequent transforming or aggregating steps, would have been attained.

Claims: CLAIMS 1. Method for crushing asbestos containing waste (ACW), characterised in that the material to be crushed, optionally sealed in containers of plastics material, is subjected to the action of a ball mill - wherein the balls are made in any suitable material - operating under inert fluid, to obtain a product with sizes and granulometric distribution suitable to subsequent aggregating or transforming steps aimed at the disposal thereof , and in that the optional container is extracted substantially uncrushed at the end of the crushing cycle. 2. Method for crushing asbestos containing waste according to claim 1, wherein the ball mill is a tumbling mill. 3. Method for crushing asbestos containing waste according to claim 1 or 2, wherein the balls of the mill are in alumina. 4. Method for crushing asbestos containing waste according to claim 3, wherein the balls of the mill are in 90% alumina. 5. Method for crushing asbestos containing waste according to any one of the claims 1 to 4, wherein the inert fluid under which the mill operates is water. 6. Method for crushing asbestos containing waste according to any one of the preceding claims, wherein the crushed material has a granulometry ranging from 5 to 500 μm and a granulometric distribution making it suitable to the subsequent aggregating or transforming steps aimed at the disposal thereof. 7. Asbestos containing waste, characterised in that it has a granulometry ranging from 5 to 500 μm, in that it has a granulometric distribution making it suitable to the subsequent aggregating or transforming steps aimed at the disposal thereof and in that it is obtainable with the method of claims 1 to 6. 8. Method for the crushing of asbestos containing waste, and asbestos containing waste as hereto described, exemplified and claimed.

Inventors: IMERITO ALDO, IMERITO, ALDO
Applicants: ECOTEC SRL, IMERITO ALDO, ECOTEC S.R.L., IMERITO, ALDO
Application year: 2001
Main classification: B09B3
IPC codes: B02C17, B09B3