Lead Acid Storage Battery Manufacturing, Secondary Lead Smelting and Processing Sector

Case Studies

State Board Officials visited the unit of M/s. HBL Power Systems Ltd. at Mehboob Nagar, Hyderabad. HBL is one of the leading manufacturer and supplier of a wide range of batteries. These batteries are widely used for telecom, aviation, automotive, railways and industries. This unit manufactures Pb-acid battery. The unit comprises of 77 acre land, out of which one third is greenery. Unit runs generally in two shifts in a day. Pb ingot and Pb dross are used as main raw material which are purchased from India, China, South Africa. This unit has production capacity of 1000 batteries per day.
Different types of lead acid batteries are :
Flat plate VRLA
Pure Lead-Tin VRLA
Tubular gel VRLA
Ultra low Maintenance Tubular
Miners Cap Lamp
The unit is an integrated battery manufacturing unit. The unit has its own battery container
manufacturing division as well as used battery recycling division to ensure safe reuse/r ecycle of lead
scraps that are generated from the used batteries.
This unit has following divisions :
 
Plastic Moulding Division
Virgin granules of ABS, PP, LDPE, HDPE are used as raw materials for manufacture of Pb - acid battery container. Process is raw material dehumidification, charging into screw barrel cylindrical heat chamber and finally moulding. This section has capacity of 660 T/ 19 machines. Product rejection is 1.5 - 2 % which are also reused.
 
Preparation of MS Box Container from MS Sheet
Mild Steel (MS) containers of the battery are manufactured at the unit from MS Sheet using semiautomatic welding machines. Production capacity is 40 nos.containers/hr.
 
Powder Coating Division for MS Container
Stages are as follows -
  • Degreasing - by Meta Clean ( a biodegradable surfactant) at a temp. of 70-80o C and residence time of 10-15 min.
  • Water rinse - Process pH is 7-9 at ambient temp. with residence time 1-2 min.
  • De rusting - by Phosphoric acid at ambient temp. having residence time 5-10 min.
  • Water rinsing - Process pH is 5-7 at ambient temp. with residence time 1-2 min.
  • Activation - by Refine 2/2 at pH 8.5-10, and at ambient temp. with residence time 1-2 min.
  • Phosphating - by zinc tri phosphate( Phosband 511T) at a temp. of 50 -55o C and residence
    time of 5-10 min.
  • Water rinsing - by DM water at pH 5-7, and at ambient temp. with residence time 1-2 min.
  • Passivation - by acidic liquid chemical (Passtreat) at pH of 4-5 and at a temp. of 65-75o C and residence time of 1-2 min.
  • Dry off oven
  • Powder coating into an enclosed chamber where APC device is multicyclone .
  • Curing oven - temp is 200o C.
 
Battery Assembling Unit
The Steps are -
  • Pb plates are used as (+) ve and (-) ve electrodes. In between separators are applied.
  • Charging points are welded on to lead plate by LPG welding.
  • Plate assembly are welded by automatic squeeze welding.
  • Plate assembly are kept within plastic container and heat sealing is applied.
  • Leak testing of container is done.
  • Electrolyte (sulphuric acid) filling for cell formation. To control cell temp. batteries are dipped into water bath for 96 hrs.
  • Automatic gel filling into battery in acid : silica gel proportion of 10 : 1.
  • Charging, discharging and capacity testing - 120 batches are charged at a time as one batch contains 20 batteries.
 
Metal Recycling Section
HBL has its own used battery recycling division. Initially, manual separation of plastic and Pb metal are done from the waste batteries. Then the metal part is sent to smelting and refining section.
  • Smelting Section
    The unit has 3 nos. F. O. fired rotary furnace. Each has capacity of 1 batch / day. 1 batch is 5 T metal. 1 batch takes 7 -8 hrs. In furnace, scrap metal with charcoal are charged through front manhole. Battery assembling unit
    Product is taken out through bottom manhole. Fumes coming out from the furnace enters into settling chamber, heat exchanger, cyclone separator, bag house and then stack of height of 30 m from G L.
  • Alloying Section
    Unit has 4 nos. F. O. fired vertical refining melting pot. Each pot has capacity of 10 T/batch. Each batch takes 24 hrs. Top fumes are drawn into water scrubber, ID fan and finally stack of height 30 m from GL.
 
Lead Sub Oxide
Molten Lead at 450o C is pumped into top covered vessel fitted with agitator. Product is collected from cyclone, and bag house with the help of ID fan.
 
Red Lead Unit
Unit has 2 nos. red lead furnaces. Lead sub oxide powder is charged into HSD fired brick lined furnace fitted with agitator. The furnaces are provided with water scrubber, ID fan and finally stack of height 30 m from GL.
 
Effluent Treatment Plant
Effluent is generated from acid, acid- gel filling , cell formation, gel preparation, acid preparation, floor washing activities. The unit has installed a full-fledged effluent treatment plant alongwith R.O.Plant. The treated water from the R.O. Plant is reused.
The ETP consists of the following components:
  • Grit Chamber
  • Holding tank
  • Settling tank
  • Neutralization tank
  • Stabilization tank
  • Sand and activated carbon column filter
  • R.O. Plant - 13 KLD water which is recycled and RO reject is sent to double effect evaporator system.
  • Double Effect Evaporator - produces 12 KLD condensate which is cooled and reused as process water. Concentrate from DEE is 1 KLD which is treated as hazardous waste.