582
M. Maccagni and E. Guerrini
In lead production, secondary lead production overtook primary production and
both the technologies had to face a lot of environmental constraints that pushed
these technologies to go through significant improvements becoming safer and more
environmentally friendly. The strong reduction in emissions data, as well as blood
lead data within lead production plants, demonstrates that a properly operated lead
production plant is no more dangerous than other metals having an infinitely better
reputation than the lead. This result was possible because of the steady introduction
of new processes, new equipment, and new concepts to continuously update the
existing processes that, currently, are only pyrometallurgical.
Hydrometallurgical/electrochemical processes are welcome as they are more
selective, more environmentally friendly, and able to reduce the emissions and the
generation of wastes typical of a pyrometallurgical process.
Engitec started investigating this kind of processes since thirty years ago trying
different systems and different chemical approaches till, a few years ago, the FAST
Pb Process was patented.
The FAST Pb Process is a way to produce metallic lead from oxidized Pb bearing
materials, in particular from lead acid battery paste, through an innovative and unconventional approach. The first application for this electrolysis was an electrochemical
pre-removal of lead within Engitec’s chloride zinc electrowinning EZINEX
® Process. This electrolysis was first performed in a tubular cell and was never fully
developed. Unfortunately, the EZINEX
® Process was limited to the first plant and
was decommissioned for non-technical reasons after 4 years operation.
At the beginning, the FAST Pb Process was supposed to be used only on desulphurized paste. Paste desulphurization is a common unit in Engitec’s battery recycling
process, the CX
® Integrate Process, used to remove the sulphur before feeding the
paste to the furnace to avoid, or at least minimize, SO 2 emissions. We were concerned
about building up sulphates in solution that, sooner or later, were supposed to create
problems in the electrochemical system. However, after extended test campaigns, the
viability of the same process using undesulphurized paste was demonstrated. Some
further considerations and studies, caused us to realize this new approach, could
deeply change and improve the lead acid battery recycling process.
Some other oxidized lead bearing materials were successfully tested in the demo
plant built at Engitec’s laboratory demonstrating the robustness of the process.
The FAST Pb Process
The process is based on an ammonium chloride electrolyte and a flow cell, which is
the true novelty of the process, where Pb is not plated in the traditional form of a sheet
but in a non-adherent flake form. These Pb flakes are stripped off the cathode and
transported out of the cell by the electrolyte flow. This electrolysis uses a chloride
electrolyte that usually produces anodic chlorine. Engitec’s EZINEX
® experience
demonstrated that in the presence of ammonium/ammonia in a buffered solution, the
chlorine will immediately react with ammonium producing nitrogen.
M. Maccagni and E. Guerrini
In lead production, secondary lead production overtook primary production and
both the technologies had to face a lot of environmental constraints that pushed
these technologies to go through significant improvements becoming safer and more
environmentally friendly. The strong reduction in emissions data, as well as blood
lead data within lead production plants, demonstrates that a properly operated lead
production plant is no more dangerous than other metals having an infinitely better
reputation than the lead. This result was possible because of the steady introduction
of new processes, new equipment, and new concepts to continuously update the
existing processes that, currently, are only pyrometallurgical.
Hydrometallurgical/electrochemical processes are welcome as they are more
selective, more environmentally friendly, and able to reduce the emissions and the
generation of wastes typical of a pyrometallurgical process.
Engitec started investigating this kind of processes since thirty years ago trying
different systems and different chemical approaches till, a few years ago, the FAST
Pb Process was patented.
The FAST Pb Process is a way to produce metallic lead from oxidized Pb bearing
materials, in particular from lead acid battery paste, through an innovative and unconventional approach. The first application for this electrolysis was an electrochemical
pre-removal of lead within Engitec’s chloride zinc electrowinning EZINEX
® Process. This electrolysis was first performed in a tubular cell and was never fully
developed. Unfortunately, the EZINEX
® Process was limited to the first plant and
was decommissioned for non-technical reasons after 4 years operation.
At the beginning, the FAST Pb Process was supposed to be used only on desulphurized paste. Paste desulphurization is a common unit in Engitec’s battery recycling
process, the CX
® Integrate Process, used to remove the sulphur before feeding the
paste to the furnace to avoid, or at least minimize, SO 2 emissions. We were concerned
about building up sulphates in solution that, sooner or later, were supposed to create
problems in the electrochemical system. However, after extended test campaigns, the
viability of the same process using undesulphurized paste was demonstrated. Some
further considerations and studies, caused us to realize this new approach, could
deeply change and improve the lead acid battery recycling process.
Some other oxidized lead bearing materials were successfully tested in the demo
plant built at Engitec’s laboratory demonstrating the robustness of the process.
The FAST Pb Process
The process is based on an ammonium chloride electrolyte and a flow cell, which is
the true novelty of the process, where Pb is not plated in the traditional form of a sheet
but in a non-adherent flake form. These Pb flakes are stripped off the cathode and
transported out of the cell by the electrolyte flow. This electrolysis uses a chloride
electrolyte that usually produces anodic chlorine. Engitec’s EZINEX
® experience
demonstrated that in the presence of ammonium/ammonia in a buffered solution, the
chlorine will immediately react with ammonium producing nitrogen.