The present invention relates to a method for heating an asbestos-containing waste product and removing the resulting safe product, comprising the steps of placing an asbestos- containing waste product on a platform, transporting the

platform including the product into a kiln, heating the platform including the product and removing the product from the platform after heating by tilting the platform.

A variety of products containing asbestos fibers were used in the past because of their excellent insulating and fire- resistant properties, for example building materials. When asbestos was used for its resistance to fire or heat, the fibers were often mixed with cement, resulting in asbestos cement. It is known that prolonged inhalation of asbestos fibers can cause serious illnesses such as asbestosis. Therefore, the use of asbestos has been restricted in many countries. The demolition of a building which contains a large amount of asbestos-based materials is mostly deconstructed piece by piece. The asbestos- containing demolition materials are wrapped at the location of demolition and transported to a recycling site. In the

Netherlands about 80,000 tons of asbestos-based demolition materials, such as corrugated plates and sewer pipes, must be processed annually.

EP 1 277 527 is related to a method for converting an asbestos-containing waste product into a safe asbestos-free product. The asbestos-containing waste product is supplied to a tunnel kiln. During a predetermined residence time the waste product is exposed to a temperature of about 600-1000 ⁰ C . As a consequence, the asbestos fibers contained in the asbestos- containing waste product are dehydrated. Due to the release of water the actual chemical structure of the asbestos fibers is essentially retained, and a pseudomorphic water-free fiber structure is produced. It appears that the fibers become brittle after the heat treatment. The resulting water-free fiber

structure is destroyed, forming the physiologically harmless asbestos-free product, which has a cementitious chemical

composition with the character of a secondary raw material suitable for the cement industry, for example. The resulting harmless product can also be used in non-asbestos building material products, for example as a filler.

After the heat treatment the product is removed from the platform by tilting the platform. This appears to be very effective in order to remove the safe asbestos-free product from the platform.

Since the platform is also susceptible to a high temperature during the heat-treatment the present invention aims to provide a method wherein the method can be performed

reliably .

For this purpose the platform comprises separate heat- resistant elements which are engaged together before tilting the platform.

The separate heat resistant elements allow the platform to expand and shrink during heating and cooling down to a great extent, respectively. The risk of damaging the platform during the heat treatment is minimized, for example compared to a platform which is made of a single piece. In order to tilt the entire platform the separate elements are engaged together before tilting.

In a practical embodiment the heat-resistant elements are supported by a mobile carrier. The carrier may be used to transport the product - and the platform - into the kiln as well as to transport the heat-treated product out of the kiln to a site where the product is discharged from the carrier.

The step of heating may be performed in a continuous kiln or tunnel oven through which the carrier is displaced. The platform may comprise a matrix of the separate elements in a horizontal plane including at least two rows of the separate elements in a first direction and at least two rows of the separate elements in a second direction perpendicular to the first direction. Different numbers of rows in both

directions are conceivable.

The separate elements may be block-shaped and they are preferably made of a refractory material. Numerous dimensions of the separate elements are conceivable.

In an advantageous embodiment each of the separate elements is provided with at least a hole, in which holes pin- shaped protrusions are inserted in order to engage the separate elements together.

The holes of the separate elements of the platform may be parallel. This provides the possibility of engaging a number of elements simultaneously by means of a fork-shaped apparatus.

The holes may be through-holes, wherein one pin-shaped protrusion is inserted into holes of at least two adjacent separate elements. Preferably, the holes are aligned, hence facilitating the insertion of the protrusion.

The protrusions may be inserted from opposite sides into holes of a row of separate elements. For example, a row of elements that are located behind each other in the same

direction as the centre lines of the holes such that the

respective holes are aligned, can be engaged in a stable manner by inserting two protrusions from opposite sides into the aligned holes.

Preferably, each of the separate elements is provided with at least two parallel holes in order to improve stability of each element during the step of tilting.

After the step of heating, the product may be put into a grinder in which the heat-treated product is pulverized such that the resulting material can be used for a next process.

The invention is also related to an apparatus for removing the safe product in the method as described hereinbefore, comprising two rows of pin-shaped protrusions which face to each other and are movable towards and away from each other in longitudinal direction of the protrusions, wherein the pin-shaped protrusions are mounted to a frame that is tiltable with respect to a basis. The basis may be fixed to the floor. The frame can also be adapted to lift the platform before tilting .

The invention will hereafter be elucidated with

reference to the very schematic drawings illustrating an

embodiment of the invention by way of example.

Fig. 1 is a schematic side view of a mobile carrier including a platform supporting an asbestos-containing waste product, illustrating a part of an embodiment of the method according to the invention.

Fig. 2 is a frontal view of the carrier of Fig. 1, illustrating a different step of the method.

Fig. 3 is a top view of the carrier as shown in Figs. 1 and 2, in which the product is not shown.

Fig. 4 is a similar view as Fig. 2, but showing a next step of the method.

Figs. 1-4 illustrate different steps of an embodiment of the method according to the invention, wherein an asbestos- containing waste product 1 is heated after which the resulting safe asbestos-free product is removed.

Fig. 1 shows an asbestos-containing waste product 1 which is placed on a platform 2. The platform 2 is supported by a mobile carrier 3 which is driven through a continuous kiln or tunnel oven (not shown) . The carrier 3 including the platform 2 and the asbestos-containing waste product 1 are exposed to a temperature of 600-1000 ⁰ C during a predetermined residence time in the kiln. After the heat treatment the product 1 on the platform 2 looks like the same as before the heat treatment, but is now a safe asbestos-free product 1. The carrier 3 including the platform 2 and the safe product 1 is transported to a location where the product 1 will be removed from the platform 2 and put into a grinder (not shown) in which the heat-treated product 1 is pulverized.

The platform 2 is formed of a matrix of separate heat- resistant elements which are made of a refractory material, in this case block-shaped refractory bricks 4. Fig. 3 shows that the matrix of refractory bricks 4 extends in a horizontal plane and comprises three rows of bricks 4 in a driving direction X of the carrier 3 and three rows of bricks 4 in a transverse

direction Y perpendicular to the driving direction X.

Alternative numbers of rows are conceivable.

Each of the bricks 4 is provided with two parallel through-holes 5. The matrix of bricks 4 is arranged such that the respective through-holes 5 of two adjacent bricks 4 in transverse direction Y are aligned.

Figs. 2 and 3 show an apparatus 6 which has two rows of pin-shaped protrusions 7 which face to each other. The apparatus 6 is adapted to move the rows of protrusions 7 to and from each other in transverse direction Y as indicated by arrows in Fig. 3. The mutual distances of the protrusions 7 in driving

direction X correspond to the locations of the corresponding holes 5 of the bricks 4 on the mobile carrier 3.

Fig. 3 illustrates a condition before the protrusions 7 are inserted into the holes 5 of the bricks 4, whereas Fig. 2 illustrates a condition in which the protrusions are inserted into the holes 5 from opposite sides of the platform 2. In this stage the bricks 4 are engaged together by the apparatus 6. In a next step the apparatus 6 lifts the platform 2 including the product 1 and tilts the platform 2 such that the product 1 moves downwardly as shown by an arrow in Fig. 4. As mentioned above the product 1 can be put into a grinder for pulverizing the product 1 and use the resulting powder as a filler for other products, for example.

After removing the product 1 from the platform 2 the bricks 4 can be placed back together onto the carrier 3 by means of the apparatus 6 such that the carrier 3 is ready for supporting and heat treating a next product.

The invention is not limited to the embodiment shown i the drawings and described hereinbefore, which may be varied in different manners within the scope of the claims and their technical equivalents.