In this process the Primary aim is to recover Lead Metal from the Raw Materials. Metallics and Lead Scrap received from the Battery Breaking Process are unloaded/shifted directly in the Plant with the help of pallet trucks or Loader so as to charge in to the Rotary Furnace.
With the help of Scoop attached to Fork Lift this Charge is fed into the preheated Furnace. Charging can be done manually also in some cases where Furnace capacity is very small. Calculated quantities of Chemicals are added to the Furnace along with Charge or Charge mix.
Under the heat from the Burner and with the chemicals, few of the chemical reactions that take place during the Smelting Process are as under.
PbSO4 + Na2 CO3 + Fe --------------- PbCO3 + FeNa2 S
PbCO3 + C ------------------------------- PbO + CO2
CO2 + C ----------------------------------- 2 CO
PbO + CO --------------------------------- Pb + CO2
2 PbO + C --------------------------------- 2 PB + CO2
PbO2 + C ---------------------------------- Pb + CO2
PbSO4 + 2 C ------------------------------ PbS + 2 CO2
PbS + Fe ----------------------------------- Pb + FeS
2PbSO4 + Na2CO3 + Fe + 9 C------- 2 Pb + FeNa2S + 9 CO + CO2
4PbS + 4Na2 CO3---------------------- 4 Pb + 3Na2S + Na2 S4 + CO2
Other fluxes also are added whenever required to get best lead recovery and fluid slag. When the Smelting Process is completed the Metal is tapped in to the Moulds / Trays. Slag is tapped separately.
The Lead blocks on cooling are lifted from Moulds by using Crane and added to Refining Kettles or shifted to open area by using Forklift. The Lead Recovered thus is associated with other miner impurities with it and therefore is called Crude Lead or Recycled Lead.
During the Smelting process the fumes formed are passed through a series of Pollution control equipments before it is emitted to atmosphere. The main pollution control system consists of Expansion Chamber/Quenching Tank, Cooling Towers, Cyclones, Spark arrestor, Ducts and Metallurgical Bag House, Exhaust Blower and the Stack. Therefore, fumes/gases emitted through the stack are very clean and are quite within the specified limits.
To arrest fugitive emission fumes if any emitted during the smelting process or tapping of molten Lead and slag, a hygiene hood is provided on top of Furnace which is connected to a SANITARY BAG HOUSE. The emissions are passed through Cyclone, FILTER bags, wet scrubber etc. and are cleaned completely before passing to stack from Exhaust blower.
The Flue Dust generated in the Pollution Control System during the Smelting Process is recycled in Rotary Furnace.