Page 204 - Mechanic Diesel - TT

MECHANIC DIESEL - CITS

At each of these stages, lead fumes and dust are released into the air, contaminating both the workplace and the
wider environment. The use of automated, enclosed processes with pollution control devices can reduce these
emissions.
In a typical automated enclosed process, the lead batteries are broken up in a hammer mill or shredder and
the pieces are fed into tanks filled with water. Here gravity is used to separate the components: the lead and
heavy materials sink to the bottom and the plastics rise to the top. The plastic materials are skimmed away and
the liquid, including the sulfuric acid electrolyte is drawn off. The metallic components are channeled to closed
furnaces for smelting and refining and then piped into casting moulds. Waste from recycling is collected, treated
and disposed of at a designated waste disposal site
In a manual process the batteries are drained then broken up with electric saws, machetes or axes. The
components are separated by hand into piles. The lead components are carried to the furnace or taken on an
open conveyer belt. The furnace may, in the worst case, be no more than an open pot on a fire. The molten lead
is then poured into casting moulds.
Lead release and exposure during recycling
At the collection and transportation stage, the sulfuric acid electrolyte solution is sometimes drained out to reduce
the weight of the batteries or because a higher price is offered for drained batteries. If not done at this stage then
the electrolyte may be drained out at the recycling site (in some enclosed processes the batteries are not drained
prior to crushing). In addition, electrolyte may leak out of damaged batteries during storage and transportation.
If adequate precautions are not taken to avoid skin contact, the acid will cause corrosive injury. The electrolyte
contains dissolved lead and, if the electrolyte leaks out or is poured onto the ground rather than into collection
tanks, the lead becomes incorporated into soil particles, which subsequently become a source of lead dust.
Pouring the electrolyte into ponds or streams will contaminate water that may be used for drinking, fishing and
cooking.
Manually breaking up the batteries releases lead particles and lead oxide dust, which are a source of lead
exposure to the worker. The dust and particles also settle in the surrounding soil and may be blown to more distant
areas, contaminating the wider environment and becoming a source of exposure to the community. Hammer mills
and shredders may release lead mist, which can dry and release lead dust if disturbed. Dust settled on vibrating
equipment can become re-suspended in air and inhaled.

During the separation process, water used in automated systems for separating lead from other components
becomes heavily contaminated with lead compounds. If this leaks or is not treated before disposal it will
contaminate the ground or soil. As this water evaporates it leaves a residue of fine lead dust that may then be
dispersed by wind

When lead components are moved around the recycling site, e.g. on open conveyor belts or in wheelbarrows,
and when they are shoveled into the furnace, lead fragments and dust are released. The temperatures used
for refining lead can be up to 1000 °C, which generates large amounts of lead fume. If the furnace is not under
negative pressure or if the plant has inadequate ventilation and/or emission controls, the fumes will be inhaled by
workers. Lead fumes are particularly
hazardous as the small particle size enables the lead to be inhaled into the lower respiratory tract and absorbed.
The fumes will eventually settle as lead particles on surrounding surfaces and the soil, creating lead dust, which
can also be inhaled. Fugitive lead emissions from these sources can be substantial and are more difficult to
control. Sometimes ash from the smelting process is manually sifted to retrieve metal particles, dispersing lead-
contaminated dust into the air
Fume, lead particles and dust released at various stages in the recycling process will also settle on the skin, hair
and clothes of workers. If workers do not wash and change clothes before returning home this lead becomes
a source of take-home exposure to household members and even, potentially, to the wider community. Lead
poisoning in the spouses and children of lead workers, caused by transfer of lead from the workplace to home,
has repeatedly been documented

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CITS : Automotive - Mechanic Diesel - Lesson 57 - 61