In the field of extractive metallurgy three routes have been identified for further upscaling to pilot stage. These routes are:

Reduction roast ammonia leach (National Metallurgical Laboratory , Jamshedpur)

Ammonia sulphur dioxide leach (Regional Research laboratory , Bhubaneswar )

Dilute sulphuric acid pre-Ieach pressure leach (Hindustan Zinc limited, Udaipur).

At least two of these routes will be, upsca1ed to the pilot plant stage (capable of handling 250 kg of nodules per day) by 1992. Vigorous efforts are being made in this direction.

Regional Research laboratory , Bhubaneswar, National Metallurgical , laboratory , Jamshedpur and Hindustan Zinc limited, Udaipur which are carrying out R&D work on extractive metallurgy , conducted further trials for firming up process parameters for upgradation to pilot plant stage.