Igst credit/refund of re-export of customs rejected goods

An import is made (100 Tons). Bill of entry for home consumption made and IGST paid on full 100 Tons. .

On physical examination, customs disallowed import of 15 tons. This 15 tons is re-exported.

Question

1. Is it possible to claim IGST ITC on full 100 Tons or on only 85 Tons?

2. If ITC allowed on 15Tons, whether this ITC on 15Tons can utilised on other domestic sales of company or have to be applied for refund?