Outokumpu Oy

Timo T Talonen

Maija-Leena Metsarinta

Jaakko T Poijarvi

Esko O Nermes

Tuula S Makinen

Erkki V Krogerus

Jaakko T I Poijarvi

The present invention relates to a method for removing sulphur dioxide and possible hydrogen sulphide as well as nitric oxides from exhaust gases by means of sulphides in a liquid phase so that the sulphur is recovered in the form of molten elemental sulphur. The soluble sulphates formed in the scrubbing are regenerated after a known fashion by means of sulphides or by reducing back into sulphides and are conducted back into the sulphur dioxide absorption stage.

Method for removing sulphur in elemental form from gases containing

The invention relates to a method for cleaning exhaust gases weak in sulphur dioxide, or sulphur dioxide and hydrogen sulphide. In order to remove the sulphur content of an exhaust gas, the exhaust gas is absorbed into a solution containing sulphide. Thereafter into the solution is added an agent which causes any unstable compounds of sulphur and oxygen, such as thiosulphate and polythionates, which are formed in the scrubbing solution, to decompose into elemental sulphur and sulphate in the autoclave whereinto the scrubbing solution is fed. The pH of the solution emerging from the autoclave is adjusted to stay within the range 2.0-2.9.

Method for removing the sulphur content of a weak gas containing sulfur

A method for the continuous recovery of non-iron metals from a molten metallurgical slag containing lead, copper or nickel by continuously reducing the layer with carbon dust. The metal layer produced at the furnace bottom is maintained sufficiently thin so that it is between 0 and 20 mm thick. Injection of carbon dust into the metal layer is avoided.

Method for continuous reduction of molten metallurical slag in an

The invention concerns a means for separating molten particles from the exhaust gases of metallurgical furnaces and for returning them to the furnace space (3). As taught by the invention, a molten dust cyclone has been provided substantially within the furnace space (3) or in its immediate vicinity, this cyclone comprising a vertical cylindrical chamber (4), a passage (8) leading from the furnace space (3) tangentially to chamber (4), an exit aperture (5) in the upper part of the chamber for removing the gas and a tap aperture (6) in the lower part of the chamber for returning to the furnace space (3) the solid and molten material that has separated from the gas. The invention furthermore concerns a way recover lead from the exhaust gases of a metallurgical furnace by regulating the oxygen partial pressure in the exhaust gases to be in the range of about 10.sup.-16 to 10.sup.-10 atmospheres at temperature 1250.degree.-1450.degree. K. and by subjecting the exhaust gases immediately to centrifugal separation to the purpose of separating lead fog droplets from the gas to the purpose of returning the molten lead to the furnace.

Means for separating solid and molten particles from the exhaust gases

A procedure based on suspension smelting has been developed for producing lead bullion from sulphidic concentrates in which the proportion of iron and of slag-forming substances is low. In the procedure oxygen or oxygen-enriched air is used. The slag containing lead oxide that is formed is in equilibrium with the sulphur-containing but refinable lead bullion. The lead oxide content of the slag may be lowered without increasing the sulphur content of the lead bullion by regulating the temperature, the FeO+CaO/SiO.sub.2 ratio and the degree of oxidation. In order that the highest possible amount of the lead contained in the concentrate might be recovered from the settler (3), the quantity of lead compounds in the gas phase is minimized and a hot cyclone is used in the uptake shaft (4) of the smelting furnace.

Procedure for producing lead bullion from sulphide concentrate

Lead is recovered from a lead-bearing sulfidic concentrate by heating the concentrate in such a manner that lead and its compounds pass into the gas phase. The oxygen pressure in the gas phase is adjusted by oxidation or reduction in order to cause the compounds of lead to react with each other to form lead, and the gas phase is cooled in order to condense the metallic lead out from the gas.

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Nakkila, Finland

Timo T Talonen