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RESIDUAL ULTRA-FINE PYRITE AS A RAW MATERIAL FOR NON FERROUS METALS RECOVERY AND SIMULTANEOUS SULPHURIC ACID PRODUCTION.

Objective

DEVELOPMENT AND IMPLEMENTATION OF A SIMPLE, ECONOMICAL PROCESS FOR THE UPGRADING OF BASE METALS CONTAINED IN PORTUGUESE PYRITES.
Tailings directly related to the sulphides of nonferrous metals ores consist in ultrafine residual pyrite issued from the ore beneficiation.
These residual pyrites are a cheap raw material for sulphuric acid production. Because such tailing material is unusually fine, laboratory and pilot plant tests are required in order to indicate the possible and most suitable processing methods.

The following recommendations have been put forward for the processing the Portuguese ultrafine pyrite.
The filtration of the ultrafine residual pyrite is feasible without previous hydrocycloning to eliminate the finest particles. Pressure filtration is required because of the specific cake resistance. Membrane squeezing and blowing air through the cake is essential for reaching sufficient low residual moisture in the cake. Nevertheless, if in the residual pyrite the proportion of submironic particle size is high and finer than that tested, difficulties in the filtration operation can be foreseen. In that case, a hydrodynamic treatment before the filtration would be useful.

As far as the filtration feed is concerned, the viscosity of the pulp has to be kept in low range (below 70% of dry solids) for securing a uniform filling in the filter chambers. The blowing air is the slowest operation in the sequential cycle of the pressure filtration so the blowing has to be limited to the highest acceptable residual moisture reached. Therefore, automatic sophisticated press filters with membrane for cake squeezing, air blowing through the cake and filter cloth washing are beneficial to the process.
An adequate pulp has to be prepared in a surge mixing tank. Heavy agitation has to be operated in the whole volume of the pulp. Before the roasting, the filter cake has to be treated in a desintegrator in order to destroy the lumps and limit the reamaining clumps.
The roasting has to be carried out in fluidized bed roaster in dead roasting conditions if the valuable elements are not worth of recovery. But if remaining valuable elements such as copper and gold are to be recoverd then sulphatizing roasting is recommended. The specific rate of the roaster is similar to others already in operation for ultrafine pyrite but more attention has to be paid to the boiler elements installed in the sulphur dioxide gas circuit in the case of waste heat recovery with sulphatizing roasting.
THIS RESEARCH CONSISTS OF DEVELOPING THE FULL USE OF THE NON-FERROUS RESIDUES CONTAINED IN PYRITES.
THIS STUDY MAINLY CONCERNS:

- THE REMOVAL OF THE RESIDUAL WATER IN THE FINES;
- ROASTING;
- METAL RECOVERY BY MEANS OF HYDROMETALLURGY.

Topic(s)

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Call for proposal

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Coordinator

Produits Chimiques et Engrais du Portugal SA - SAPEC
EU contribution
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Address

2901 Setubal
Portugal

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Total cost
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