You should go with core branches at NIT Warangal or Surathkal as other option in IITs that you have won't garuntee you placements. The polymer science and industrial chemistry doesn't garuntee decent placements, but if you are very interested the ISM mining course will definitely have great placement options. Indian School of Mines is famous for their mining related courses and Manny big companies related to petroleum, mining etc visit for placements than in other IITs for same branch. Packages are above 10lpa and I know seniors who have been placed from there.
But the point is you have to decide if career in mining is what you want- the working conditions won't be pleasant but pay will be very high. Decide about this, and if you don't want to, then you have core branches at NIT Warangal and Surathkal which are the best NITs in India.