Method for further refinement of blast furnace slag - has molten slag collected in vessel placed under catchment hood and lance used to blow oxygen@ air or oxygen enriched air into slag causing metal sulphide(s) to oxidise

摘要

The molten slag is collected directly from the furnace in a vessel which is placed under a catchment hood. A lance is used to blow in oxygen, air or oxygen-enriched air, causing teh slag-metal sulphides to oxidise, whereby teh sulphur comes away as hot sulphur dioxide gas which is collected in the hood and conducted away through a filter. The gas has a temp. of between 1400 and 1500 deg.C, and is cooled and diluted with air down to a temp. of 500 deg.C. This gas is then conducted into a conventional sulphuric acid plant with V2O5 as catalyst, anbd the sulphor dioxide is converted to sulphur trioxide which is then absorbed in 98% sulphuric acid. Concentrated sulphuric acid is tapped off continuously. Oxidation of the slag is exothermic, and an synthetic wollastonite is obtained which is white if not coloured mineral is added.