| Over 75 million Nickel Cadmium
(NiCd) batteries were sold in the US during the year 2000. Market
predictions indicate that the demand of NiCd batteries will
rise six percent per year until 2003. The demand for other chemistries
such as Nickel Metal Hydride (NiMH) and Lithium Ion (Li-ion)
is increasing 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 old 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 small rechargeable
batteries. Homeowners have the lowest return ratios, but this
should improve once more recycling repositories become available
and better environmental awareness is emphasized.
The NiCd battery is one of the more hazardous batteries in
terms of disposal. 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. Under no circumstances can batteries be incinerated
as this can cause them to explode.
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.
Cameras and other commercial products also use primary lithium
batteries. For proper disposal, these batteries must be fully
discharged in order to consume all metallic lithium content.
Li-ion batteries (rechargeable), on the other hand, do not contain
metallic lithium and the disposal problem does not exist. Most
lithium systems contain toxic and flammable electrolyte, however.
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 must be done manually, an operation that adds to the
cost of recycling.
If a steady stream of sorted batteries 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 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 in bulk? 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 that 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 retrievable metal. The recycling cost of alkaline is
33 percent lower than that of NiCd and Li-ion because the alkaline
cell contains 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 average cost of
recycling batteries is $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 is setting 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.
Summary
Proper disposal of batteries is a growing concern, especially
with NiCd. In spite of the move to environmentally friendlier
chemistries such as NiMH and Li-ion, the NiCd battery continues
to fill an important market niche. Many applications do not
run satisfactorily with newer battery systems. Portable equipment
that must rely on the durable and forgiving power source of
the classic NiCd are power tools, biomedical devices and two-way
radios.
Rechargeable batteries produce far less waste than the non-rechargeable
variety because they can be reused hundreds of time. In terms
of preserving the environment, switching to rechargeables makes
common sense. The most durable rechargeable battery is the NiCd,
a chemistry that is also the least friendly if carelessly discarded.
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