Throughout the process of dismantling lead-acid
batteries, separating and smelting the lead, microscopic
lead particles can be released. The effects of lead
particles in the air is a physiological threat and therefore
stringently regulated by appropriate national and regional
laws and agencies.
The industry is standardizing on PTFE matrix filter media
in process lead applications because of its superior
loading and release properties. It must be noted that
media choice is only part of the equation and overall
filter/collector design needs to be closely controlled to
secure the highest filtration standards.
Lead particles can be released
during recycling processes
In the USA, permissible facility-wide lead levels in
manufacturing or recycling plants are 0.2mg/m3. Other
countries in the Americas, notably Mexico, are improving
pollution control with a view to meeting identical levels as
the USA by 2023.
To meet ever more stringent standards, it has been
standard practice to include an in-line HEPA (High
Efficiency Particulate Air) filter in the outlet duct from a
typical dust collector.
One disadvantage to this approach is the regular
replacement cycles required for HEPA filter media,
requiring the entire filtration system be shut down for the
exchange operation. Without the filtration system, the
recycling or production has to be halted. Shutdowns to
process filtration cost the business enormous amounts in
lost production revenue.
A novel solution to the shutdown problem is to design a
modular filter bank system.
Rather than a single bank of HEPA filters in the outlet
ductwork, this design splits the HEPA filters into
four or more equal banks that are attached to separate
baghouse filter modules. A key issue is that the design
must size the baghouse to be run with only 3 modules
online. One of them can be isolated and maintained
while the rest continue to operate. This results in very
little down-time for the recycling operations.
In addition to this unique design aspect, a pulse-jet
baghouse can include other significant, proven, timesaving
For example, the control system can determine the
exact row that a broken filter bag is in. This allows for
shorter down-time when replacing broken bags. Also, in-line particle detectors can indicate the exact location of a
Wet Scrubbers - the preferred lead filtration solution
In several reference sites in across the world, these solutions
have reduced maintenance costs and assured compliance.
Now, digital control capabilities and precise particulate
sensors are being augmented by real-time remote
monitoring. The main value of cloud-based data for lead
operations is immediate reporting of non-compliance while
retaining maximum uptime. Additionally, worker safety is
enhanced by giving plant operations immediate oversight of
key compliance information from anywhere; onsite or across
Dust Collector designed to run without all modules online
Solving the process filtration problem is only one aspect of
plant-wide compliance. For transport, breaking and storage
areas it is just as important to capture lead particles. This
is best achieved by Hi-vacuum source capture within the
work area. Fortunately, these systems are easily designed,
modeled and adapted to existing plant layouts and are
flexible enough to meet expanded production demands.
Care should be taken to secure the safety of people and
equipment during acid operations in the lead acid battery
Real-time data focuses PM tasks
Wet scrubbers are the preferred solution to neutralizing
acidic gas content. Care should be taken in scrubber design
to optimize for particle size while reducing the maintenance
footprint in a harsh environment.
Conclusion. Successful lead-acid battery recycling and
manufacture requires a holistic approach to air filtration in
order to sustain regulatory compliance and improve factory
output, but these goals are in fact complementary. Only
careful choices in overall system design and implementation
will yield a consistent result. New technologies can assure
compliance while reducing maintenance overheads.