Building roads with plastic bags in Niger

Environmental impact of end of life products: plastics, chemicals, vehicles, agri-food marketing. direct recycling and recycling (upcycling or upcycling) and reuse of good items for the trash!
Giul
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Building roads with plastic bags in Niger




by Giul » 24/01/09, 09:22

Recycling plastic bags in Niger: making pavers
to build roads, but the artisans' exhibition fears: : Shock: no masks, contact with toxic products etc.

the idea would be of interest with a suitable and secure manufacturing structure

video:
http://www.muvmedia.com/fr/reportage.php?rid=844

Same in Mali:
http://www.france24.com/fr/20080825-rep ... REPORTAGES


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Remundo
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by Remundo » 24/01/09, 11:52

Hi Giul,

This initiative is generally a good idea.

However, the methods used are too artisanal.

Indeed, the combustion of polyethylene or polypropylene theoretically only releases CO2 and H2O, but assuming complete combustion with pure oxygen.

In reality, the method presented is incomplete combustion (it burns with little air at the bottom of the oven). Carbon monoxide (CO: very powerful blood poison) is released.

There are also unburned hydrocarbons (volatile organic compound, some of which are "more or less" carcinogenic).

There can also be formation of hydrocyanic acid (HCN) because the air contains nitrogen and the high temperatures combined with the presence of "cracked" hydrocarbons can form this compound ...

Finally, sand contains many minerals, including sulfur, which can then give sulfur compounds that are oxidized (SO2, SO3) and sometimes acidic (H2SO3, H2SO4)

White smoke is a clever mixture of all of this.

All this to say that the "process" is dangerous for the workers.

A mechanical mixer / oven is required. The molding unit could be done by hand because it no longer smokes at this stage ... But we are in Africa ...

These few men full of goodwill, ideas and energy will quickly be tired of the corruption of their leaders and the indifference of their compatriots : Idea:
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chatelot16
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by chatelot16 » 24/01/09, 13:39

the idea is good: but the polyethylene must not burn: what burns is lost and no longer serves as a binder

it really looks like making hot mix, with gravel and tar: the machine exists: a rotary oven where the mixture of gravel and tar is heated away from air: in the flame a fuel burner

I wanted to make a small rotating oven for a long time to mix asphalt in small quantities: it will be even more interesting to mix sand and polyethylene

the heating of the mixture is quite slow: it's still more interesting to let a rotating oven turn than to stir with a shovel

but I am afraid that the principle of the rotary kiln is only good in large dimensions, or the weight of pasty material is sufficient for it to fall back: in small dimensions it will stay stuck and not mix: if it takes a mechanical stirring it complicates the production and produces wear: the sand is abrasive ...
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