Ecological pyro-hydrometallurgical technology of nickel pyrrhotite concentrate treatment with non-traditional and reagentless recovery of sulphur dioxide from low concentrated gases

Synopsis

A non-traditional method of the poor sulphur dioxide collection by the pulp of a sulphur sulphide concentrate, the middling of an autoclave-oxidation technology of pyrrhotite concentrates has been considered. The technology developed joins organically the process cycle of Nadezhda metallurgical plant (NMP) of Norilsk mining-and-metallurgical integrated works and allows to increase considerably technical-and-economic indices thereof solving simultaneously ecological problems. The results of the first step of semicommercial tests of the flowsheet are represented. On the basis of the results obtained as well as the data of other authors main stages of the process of sulphur dioxide recovery and absorbent dissolution on the basis of iron oxides are offered.

The atmosphere pollution by harmful substances has become at present a main problem of the environment protection. One of the problems are acid rains caused by sulphur dioxide emissions in the atmosphere.

Norilsk mining-and-metallurgical integrated works ejects large amount of sulphur dioxide 60% of which is ejected with low-concentrated gases. The use of traditional methods of sulphur recovery because of geographical isolation of the integrated works leads to considerable capital and operating costs and consequently to rise in the cost of finished products. The results of a tech-nical-and-economic comparison of sulphur recovery from poor gases containing 2–3, 5% SO₂ by three versions, namely

• production of marketable sulphuric acid;

• production of technical sulphur with preliminary upgrading of gases by an ammonia-cycling method;

• neutralization by a lime suspension followed by gypsum production have shown that the most effective version is the second one. The specific costs given amount to approximately 400 roubles per 1t of sulphur in finished products. The introduction of this method will lead to considerable increase of the manufacturing cost of the works finished products as a selling price of 1t of copper amounts to 65 roubles.

A unique location of the works requires the use of an unordinary solution of the problem indicated which is considered in the present paper conformably to the technology of Nadezhda metallurgical plant.