in the past week there has been a
disaster in Hungary a very sad one in
which the so-called red sludge from
processing of aluminium has escaped from
the pond where it was being
held and chemically this has had quite
serious
consequences so Hungary is a landlocked
country right in the middle of the
Europe its rivers flow into the danu
which goes right across Europe and into
the Black Sea Hungary is also a country
where there are quite a few
minerals and in this case they were
processing aluminium aluminium is a very
common mineral or element it's found all
over the world in Clays and so on but
there is a particular mineral called
bite which is hydroxide of aluminium
which is usually found mixed with iron
oxide rust to you and me and titanium
dioxide which is what you get in white
paint and the processing is chemically
pretty trivial everything is dissolved
up in cotic soda sodium
hydroxide and then out of this you get
alumina pure aluminium oxide which is
what process to make
aluminium but this process generates a
lot of waste
and the waste is red because it contains
rust soal red
sludge and this is done in many places
in the world in Australia for example
and you get huge ponds of the
sludge but Australia by comparison with
Hungary is a very um sparsely populated
country so the danger from these Lakes
is much less and what happened in this
tragic occasion is that the wall which I
think was made of mud which retained the
sludge gave way at least in part and the
sludge came out and seven people were
killed and I think probably though I
don't know the details they're more
likely to been killed because they were
engulfed in
mud than because of any of the chemistry
but the sodium hydroxide makes the
sludge alkaline alkaline is the opposite
of acid and because of the way position
of Hungary there is a danger that the
sludge can then get into the rivers and
go all the way down to the Black Sea
fortunately sodium hydroxide is not a
terribly dangerous chemical it makes the
water alkaline and in principle you can
neutralize it by putting in some acid
but you've got to make the acid just
just the right amount or you make the
river too acid which is just as
bad and when you mix it in it's not like
mixing acid in a beaker you've got a
huge River so how you add it is quite
Difficult about 10 or 15 years ago there
was a similar tragedy in Hungary where
cyanide came out from a gold mine and
cyanide can't be neutralized and is far
far more poisonous and it went all the
way down the danu to the Sea killing
fish thousands of miles away from where
it
originated so the problem in this case
is that the volume of the red sludge is
very large in fact it's possible that
some more may come out after the first
release and so it is difficult to know
what is the best way to treat it but I
think the take-home message
is that whenever people are processing
chemicals or minerals on a large
scale you have to think beforeand what
will happen if something gets out not
wait for the disaster to take place and
then start deciding what to do as far as
I'm aware by and large the red sludge is
just
left and nobody is quite sure what to do
with it eventually I think the red
sludge could be treated with acid to
make it neutral but by and large there
isn't very much that can be done with it
and it is the price that we pay for
using aluminium in
our takeaway
microwave food in our wrappers of sweets
and so on one
cannot obtain these riches from the
earth without generating some waste what
we have to do is to try and minimize the
amount of that waste and look after it
carefully