Q2. a) A sampling process for chemical analysis is carried out for a lead ore containing 5.2% of Pb which has a top size of 15 mm and lower size limit of 500 m. The liberation size of the ore is determined as 50 m. The amount of error is determined as 0.06% for PbS% (confidence level is ignored). What will be the minimum amount of sample should be taken? (21 pts)

b) It is observed that 15 mm of top size is not suitable for chemical analysis sampling and much less sample is needed for chemical assaying. What should be done in next stage? (9 pts)

gangue: 2.65 g/cm3, PbS: 7.5 g/cm3, Pb: 207.2 g/mol, S: 32 g/mol