El medio ambiente en la minería

EL MEDIO AMBIENTE EN LA MINERIA 92 - Higb degree of mecbanization and computarization - Feeding of rawmateria1s witb his natural moisture - Metallurgical reactions carried out in a cIosed vessel - Minimization of handling materials and gaseous volume - Transportation of dusty recycling materials in encIosed conveyors - Hygiene ventilation everywhere dusty and fume can be emitted and cIean- ing of tbis air in bagbouses. Sulpbur contamination is furthennore prevented by the use of tecbnical pure oxygen (95% 02) which radically reduces the gaseous volume, increasing its sulphur dioxide content for an efficient desulphurization in a standard sul– pburic acid plant. A conversion rate of S02 to S03 of 99,6% and a content of max. 50 mg!Nm 3 S03fH2S04 are acbieved after passing a standard Lurgi Sulphuric Acid Plant. Figure 4 shows tbe main principies of the QSL-Process Tbe QSL-Process is a submerged direct smelting process in whicb the con– tinuous pbase, metal and slag, is Iiquid. Continuous smelting of lead bearing materials is done in a slightly inclined and refractory lined horizontal reactor to produce lead bullion and a discardable slag. Tbe mixture ollead bearing materials, fluxes, recycled flue dust and ir neces– sary a small amount of coal is continuously fed througb charging chutes into tbe oxidation zone ofthe reactor. Here pardal oxidationoftbe sulphides under the fonnation of primary lead bullion, lead oxide slag and sulpbur dioxide gas takes place by submerged injection of tonnage oxygen. Several pairs of dual media n¡trogen protected troyeres, type Savard-Lee, for injecting oxygen are installed in tbe bottom part of tbe oxidation zone. Oxygen is additionallyblown into the gas pbase of the oxidation zone by means ofoxygen lances in order to oxidize and partly sulpbatize evaporated metals in the gas phase before entering the gas up-take radiation channel. Primary lead fonned in the oxida– tion zone and secondary lead from the reduction are combined and flow continuousIy out of the reactor through a water cooled siphon which is installed at the lower part of the reactor in the reduction zone at the front end. Tbe generated sulpbur dioxide gas in the oxidation zone leaves the reactor through a vertical radiation channel to the waste heat recovery and gas cleaningunits before enteeing into the sulphuric acid plant foe its desulphuriza– tion. A partitionwall separates the oxidation and the reduction zone. Tbe wall has an underflow opening for a controlled flow of melted lead to the oxidation zone.