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In
the past, we have already dealt with certain types of plants which,
because of their features, can, or rather could, contribute to the disposal
of certain typologies of waste, such as tires for instance, by using
them as energy sources. We have already explained that various different
European countries have been adopting this procedure for years, and
that the situation is now evolving in Italy. This trend might in fact
be quickened as a result of the BSE disease issue, and of the consequent
need to dispose of animal meal in the most effective and ecological
way. In this regard, a clear example is offered by France; indeed in
1996 in this country a first test was conducted in 4 cement factories,
differing both in the technologies they employed and in the companies
they belonged to; the test was carried out under the supervision of
public authorities and in compliance with a protocol which was jointly
decided by the Ministry of Agriculture and Environment, ADEME (Agence
de l’Environnement et de la Maitrise de l’Energie), INRS (Institut National
de Recherche et de Sécurité), the cement industry and the representatives
of butchers and of animal meal producers. The positive results achieved
through these experiments displayed no variations in the operating parameters
of cement kilns, no changes in the quality and quantity of emissions
into the atmosphere and in the features of the cement produced. Hence
the decision to proceed from the trial phase to the employment on an
industrial scale of animal meal as an alternative combustible material
in several factories belonging to the leading French companies in this
field. During the year 2000, French cement manufacturers have eliminated
200,000 t of animal meal (70,000 t of which in five cement factories
belonging to the Italcementi Group) and, following the recent extension
of the ban on animal meal, French cement manufactures are equipping
themselves to reach a consumption of approximately 450,000/year. As
mentioned above, the BSE emergency has also led Italy to consider this
possibility. Indeed, the Italian Association of Cement Manufacturers,
AITEC (Associazione Italiana dei Cementieri), at the request of the
Minister of Agriculture and of the Emergency Officer, has granted its
availability to use animal meal as combustible material in its factory
kilns. It should however be pointed out that what is being burnt is
not the animals’ carcasses or offal but only the meal obtained by adequately
processing carcasses and offal of animals which have been proved not
to be affected by BSE and which do not belong to groups of animals in
which BSE cases have been discovered. In order to supply a complete
guarantee, the meal burnt in the cement factories is covered by a veterinary
certificate stating its origin. On the other hand, for animals affected
by BSE and also for those belonging to groups in which contamination
has occurred, the use of dedicated facilities is absolutely compulsory,
with the same procedure employed for hospital waste. Another major aspect
is that, although no alterations are required on existing burning plants,
on the other hand it will be necessary to accomplish closed circuit
plants for the reception, metering and forwarding of meal to the kilns,
and to improve the emission control systems in accordance with the requirements
of the regulations which are currently being drawn up. In addition,
the meal will be transported in closed trucks, so as to avoid dispersion,
and will be subsequently stored in specially designed storage bins,
whereas the trucks will be emptied by means of a pneumatic system, or
by means of vacuum-operated hermetic mechanical systems. Furthermore,
the loading and handling cycle-air forming up to the kiln entrance will
be filtered and conveyed to the kiln without any emissions into the
environment. As regards the environmental impact, it should also be
remembered that the use of meal or of other alternative combustible
materials involves the use of the energetic power supplied by the combustion
of such products in place of the similar energetic power supplied by
the combustion of an equivalent amount of coal. Therefore, chimney emissions
do not vary, since they remain within the standard parameters provided
for by the law in force and by the cement factory operating licence.
In addition, in view of the temperatures involved (animal meal is injected
into the main burner flame which reaches a temperature of 2,000°
and in any case remains at a temperature exceeding 1,000°
for 5-8 seconds)(Fig. 1) and of
the total destruction of the meal, there is no possibility of smell
emissions from the chimneys. On the other hand, to avoid smell problems
in the surroundings of the plant where the meal is processed before
being forwarded to the kiln, the meal is to be handled in closed-circuit
plants, vacuum-operated by a filter. The air exiting the filter is then
conveyed to the kiln instead of being emitted into the atmosphere; in
any case the meal smell is simply that of dry meat. As soon as the Government
implements the new regulations covering the disposal of animal meal,
AITEC will schedule the investments required to accomplish the plants
supplying the meal to the kilns and those controlling emissions, whose
realisation will in any case require a few months. In conclusion it
may be worthwhile pointing out that, as far as the other European countries
are concerned, in addition to the already mentioned French experience,
in Switzerland animal meal has been employed as combustible material
in cement factory kilns ever since the mid 90s; in Spain an agreement
has recently been reached to this end, between the Government and the
Association of Cement Manufacturers, whereas in Belgium, in 1999, Government
authorities have in fact made it compulsory for the cement industry
to burn animal meal.
(traduzione
Interpres sas-Giussano)
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