Y6riob69rri++IirMrl^Y,^rWYlrrirrYY^iaib^riiHW M^mrlNilYWfa I , 14.11 I "I, r^kr^rle+IMIrYifl gfM"16r^rv, , 1,14 ISBN : Hi-87053-i3-4 Processing of Fines (2) Eds.: P. Bharran car7_ a. R. Singh and N. G. GcW s 7Y rrrri ONMLJarns/ redpcrr -831 007. India. 2000. 1,p 188-/98 Designing flotation process for lead-zinc ore from Nepal R. SINGH', S. K. SENGUPTA', P. N. PATHAK', S. N. PRASAD`, J. P. SRIVASTAVA', B. BANERJEE', A CHATTOPADHYAY', D. S. RAO', S. C. MAULIK' and C. K. CHAKRABARTI' 'National Metallurgical Laboratory, Jarnshecipur 831 007. India 2Nepal Metal Company Ltd., Kathmandu, Nepal ABSTRACT The paper deals with the development of a process based on froth flotation for the concentration of a lead-zinc ore from Gane.sh-Himal region of Nepal. A detailed characterisation and flotation studies were carried out under the varying process conditions. The ore was predomionantly made up of sphalerite and pyrite in association with sub-ordinate amount of galena, minor amount of pyrrhotite and chalcopyrite with dolomite as the major gangue. Under the optimum process conditions the rougher lead and zinc recovery were 96.3% and 90.8% respectively. Regrinding followed by three stage cleaning of the lead rougher concentrate resulted in cleaner concentrate assaying 79.11 % Pb with 83.4% recovery. Similarly two stage cleaning of the zinc rougher concentrate produced cleaner concentrate analysing 60.08% Zn with 80.4% recovery. Based on the studies undertaken a process flow-sheet for the concentration of the ore to individual lead and zinc concentrates has been recommended. Key words : Froth flotation, Lead-zinc ore, Process flo-n-sheet, Characterisation INTRODUCTION A rich mineralisation of lead and zinc is located in the Ganesh-Himal region of Nepal. There are six rich mineralisation of lead and zinc sulphides in an area of' 5 sq.krn. between 4,050 and 4,900 m above mean sea level. From the recent exploration the mineable ore reserves are estimated to he I million tonne con- taining 2.06%c lead and 13.30% zinc. The in situ ore grade is about 19c% as combined lead and zinc and the possible ore reserves are more than 2 million tonne' 1. 188