|
Battery Recycling
Even though the emphasis in battery research
has shifted away from NiCd to newer technologies, the NiCd
battery continues to be one of the most used rechargeable
batteries. Over 75 million NiCd batteries were sold in
the US during the year 2000. Market reports indicate that
the demand of NiCd batteries is expected to rise six percent
per year until 2003. The demand for other chemistries, such
as the NiMH and Li-ion family, is rising at a more rapid
pace. Where will the mountains of batteries go when spent?
The answer is recycling.
 The
lead acid battery has led the way in recycling. The automotive
industry should be given credit in organizing ways to dispose
of spent car batteries. In the USA, 98 percent of all
lead acid batteries are recycled. Compared to aluminum cans
(65 percent), newspaper (59 percent) and glass bottles
(37 percent), lead acid batteries are reclaimed very
efficiently, due in part to legislation.
Only one in six households in North America recycle
rechargeable batteries. Teaching the public to bring these
batteries to a recycling center is a challenging task. Homeowners
have the lowest return ratios, but this should improve once
more recycling repositories become available and better environmental
awareness is emphasized.
Careless disposal of the NiCd is very hazardous
to the environment. If used in landfills, the cadmium will
eventually dissolve itself and the toxic substance will seep
into the water supply, causing serious health problems. Our
oceans are already beginning to show traces of cadmium (along
with aspirin, penicillin and antidepressants) but the source
of the contamination is unknown.
Although NiMH batteries are considered environmentally
friendly, this chemistry is also being recycled. The main
derivative is nickel, which is considered semi-toxic. NiMH
also contains an electrolyte that, in large amounts, is hazardous
to the environment.
If no disposal service is available in an area,
individual NiMH batteries can be discarded with other household
wastes. If ten or more batteries are accumulated, the user
should consider disposing the batteries in a secure waste
landfill.
Lithium (metal) batteries contain no toxic metals,
however, there is the possibility of fire if metallic lithium
is exposed to moisture while the cells are corroding. Most
lithium batteries are non-rechargeable and are used by defense
organizations. For proper disposal, these batteries must be
fully discharged in order to consume all the metallic lithium
content. Li-ion batteries do not contain metallic lithium
and the disposal problem does not exist. Most lithium systems,
however, contain toxic and flammable electrolyte.
In 1994, the Rechargeable Battery Recycling Corporation
(RBRC) was founded to promote the recycling of rechargeable
batteries in North America. RBRC is a non-profit organization
that collects batteries from consumers and businesses and
sends them to Inmetco and Toxco for recycling. Inmetco specializes
in recycling NiCd, but also accepts NiMH and lead-based batteries.
Toxco, focuses on lithium metal and Li-ion system. Currently
only intended to recycle NiCd batteries, RBRC will expand
the program to include also NiMH, Li-ion and SLA batteries.
Programs to recycle spent batteries have been
in place in Europe and Asia for many years. Sony and Sumitomo
Metal in Japan have developed a technology to recycle cobalt
and other precious metals from Li-ion batteries. The
rest of Asia is progressing at a slower rate. Some movements
in recycling spent batteries are starting in Taiwan and China,
but no significant infrastructure exists.
Battery recycling plants require batteries to
be sorted according to chemistries. Some sorting is done prior
to the battery arriving at the recycling plants. NiCd, NiMH,
Li-ion and lead acid are often placed in designated
boxes at the collection point.
Sorting batteries adds to the cost of recycling.
The average consumer does not know the chemistry of the batteries
they are using. For most, a battery is a battery.
If a steady stream of batteries, sorted by chemistry,
were available at no charge, recycling would be feasible with
little cost to the user. The logistics of collection, transportation
and labor to sort the batteries make recycling expensive.
 The
recycling process starts by removing the combustible material,
such as plastics and insulation using a gas fired thermal
oxidizer. Gases from the thermal oxidizer are sent to the
plant’s scrubber where they are neutralized to remove pollutants.
The process leaves the clean, naked cells which contain valuable
metal content.
The cells are then chopped into small pieces,
which are then heated until the metal liquefies. Non-metallic
substances are burned off; leaving a black slag on top that
is removed with a slag arm. The different alloys settle according
to their weights and are skimmed off like cream from raw milk.
Cadmium is relatively light and vaporizes easily
at high temperatures. In a process that appears like a pan
boiling over, a fan blows the cadmium vapor into a large tube,
which is cooled with water mist. This causes the vapors to
condense. A 99.95 percent purity level of cadmium can
be achieved using this method.
Some recyclers do not separate the metals on
site but pour the liquid metals directly into what the industry
refers to as ‘pigs’ (65 pounds) or ‘hogs’ (2000 pounds).
The pigs and hogs are then shipped to metal recovery plants.
Here, the material is used to produce nickel, chromium and
iron re-melt alloy for the manufacturing of stainless steel
and other high end products.
Current battery recycling methods requires a
high amount of energy. It takes six to ten times the amount
of energy to reclaim metals from recycled batteries than it
would through other means. A new process is being explored,
which may be more energy and cost effective. One method is
dissolving the batteries with a reagent solution. The spent
reagent is recycled without forming any atmospheric, liquid
or solid wastes.
Who pays for the recycling of batteries? Participating
countries impose their own rules in making recycling feasible.
In North America, some recycling plants bill on weight. The
rates vary according to chemistry. Systems that yield high
metal retrieval rates are priced lower than those which produce
less valuable metals. The highest recycling fees apply to
NiCd and Li-ion batteries because the demand for cadmium
is low and Li-ion batteries contain little in the way
of retrievable metal. The recycling cost of alkaline is 33 percent
lower than that of NiCd and Li-ion because the alkaline
cell contains valuable iron. The NiMH battery yields the best
return. Recycling NiMH produces enough nickel to pay for the
process.
Not all countries base the cost of recycling
on the battery chemistry; some put it on tonnage alone. The
cost of recycling batteries is about $1,000 to $2,000US
per ton. Europe hopes to achieve a cost per ton of $300US.
Ideally, this would include transportation, however, moving
the goods is expected to double the overall cost. For this
reason, Europe sets up several smaller processing locations
in strategic geographic locations.
Significant subsidies are sill required from
manufacturers, agencies and governments to support the battery
recycling programs. These subsidies are in the form of a tax
added to each manufactured cell. RBRC is financed by such
a scheme.
Caution: Under
no circumstances should batteries be incinerated as this can
cause them to explode.
Important: In
case of rupture, leaking electrolyte or any other cause of
exposure to the electrolyte, flush with water immediately.
If eye exposure occurs, flush with water for 15 minutes
and consult a physician immediately.
|
