586
M. Maccagni and E. Guerrini
Impact of the FAST Pb Process on the Lead Acid Battery
Recycling Process
Despite the tests on a lot of different lead bearing materials, this new technology was developed to take care of the lead acid battery paste because we have
learned that it will have a significant impact on the overall battery recycling process,
deeply impacting several unit operations in terms of future efficiency, economics,
and environmental impact.
The most evolved current recycling process is the Engitec CX
® Process that is
highly simplified in the block diagram shown in Fig. 2.
This is a highly refined and consolidated process that has undergone extensive
changes and continuous process updates. But there are still some areas to be further
improved to obtain an even cleaner and environmental sound process. The most
important issues are:
• the paste smelting unit, along with slag and fumes management, which is the bigger
problem as far as concerns the environmental impact;
• the desulphurization unit where that cost of reactants is much higher than the revenues for the sulphate salt selling, and the evaporation cost is high and continuously
growing;
• not to be forgotten, the challenging market for the crystallized sulphate salt.
The introduction of the new FAST Pb Process can significantly change the entire
battery recycling approach. Some of the operations indicated in the previous block
diagram can be reduced, cut, and/or minimized by the introduction of this hydrometallurgical process. The process becomes simpler and more environmentally friendly
as shown in Fig. 3.
As you can understand looking at Fig. 3, the process changes where it needs to
change. In fact, desulphurization is not required anymore and this means to consequently cut also the sulphate solution purification and the big crystallization unit.
This also means to have not anymore the problem of selling the sulphate salt.
The other big change is that the big rotary furnace used for the smelting of the
paste is not required being the recovery of lead from the paste performed by the
FAST Pb Process. This means also that the big baghouse taking care of the foundry
is not anymore required.
There are several additional benefits to the FAST Pb Process not yet mentioned.
The sulphate removal can be carried out in a dedicated unit where, using a high
quality lime, a saleable gypsum can be produced. The final leaching residue contains
all the antimony from the paste, so it does not transfer through to the refinery. There is
a small amount of unleached lead also contained in the residue that can be treated by
campaign in a small furnace where the metallic grids fraction is also recovered. The
final amount of slag and ashes is very highly reduced compared to current operating
techniques. There is an evaporator for the FAST Pb Process, but the capacity is much
less than for desulphurization, and it is only to maintain the water balance in the
FAST unit, not to produce any products.
M. Maccagni and E. Guerrini
Impact of the FAST Pb Process on the Lead Acid Battery
Recycling Process
Despite the tests on a lot of different lead bearing materials, this new technology was developed to take care of the lead acid battery paste because we have
learned that it will have a significant impact on the overall battery recycling process,
deeply impacting several unit operations in terms of future efficiency, economics,
and environmental impact.
The most evolved current recycling process is the Engitec CX
® Process that is
highly simplified in the block diagram shown in Fig. 2.
This is a highly refined and consolidated process that has undergone extensive
changes and continuous process updates. But there are still some areas to be further
improved to obtain an even cleaner and environmental sound process. The most
important issues are:
• the paste smelting unit, along with slag and fumes management, which is the bigger
problem as far as concerns the environmental impact;
• the desulphurization unit where that cost of reactants is much higher than the revenues for the sulphate salt selling, and the evaporation cost is high and continuously
growing;
• not to be forgotten, the challenging market for the crystallized sulphate salt.
The introduction of the new FAST Pb Process can significantly change the entire
battery recycling approach. Some of the operations indicated in the previous block
diagram can be reduced, cut, and/or minimized by the introduction of this hydrometallurgical process. The process becomes simpler and more environmentally friendly
as shown in Fig. 3.
As you can understand looking at Fig. 3, the process changes where it needs to
change. In fact, desulphurization is not required anymore and this means to consequently cut also the sulphate solution purification and the big crystallization unit.
This also means to have not anymore the problem of selling the sulphate salt.
The other big change is that the big rotary furnace used for the smelting of the
paste is not required being the recovery of lead from the paste performed by the
FAST Pb Process. This means also that the big baghouse taking care of the foundry
is not anymore required.
There are several additional benefits to the FAST Pb Process not yet mentioned.
The sulphate removal can be carried out in a dedicated unit where, using a high
quality lime, a saleable gypsum can be produced. The final leaching residue contains
all the antimony from the paste, so it does not transfer through to the refinery. There is
a small amount of unleached lead also contained in the residue that can be treated by
campaign in a small furnace where the metallic grids fraction is also recovered. The
final amount of slag and ashes is very highly reduced compared to current operating
techniques. There is an evaporator for the FAST Pb Process, but the capacity is much
less than for desulphurization, and it is only to maintain the water balance in the
FAST unit, not to produce any products.