The recycling of lead-containing car batteries requires that they be heat treated. Melting is carried out in various units. In the past, the prevalent technology used was the coke-fired shaft furnace. This process was used by Weser-Metall up until the mid-1990s.

Since 1996, thanks to investments amounting to tens of millions, it has been possible to replace these shaft furnaces by modern, gas-fired, bath melting reactors. Instead of indirect firing, in this instance the fuel is fed directly into the chamber by means of a lance, which reduces the process energy accordingly. By continually optimising the process control, the input of lead-containing recycling material can correspondingly also be increased to just under 70%. Altogether, this results in a saving of about 80% of CO2 emissions.