VERFAHREN ZUR AUFARBEITUNG VON SODASCHLACKEN AUS DER ENTSCHWEFELUNG VON ROHEISEN

摘要

1. A method of processing slags produced by the desulphurization of molten crude iron with sodium carbonate, wherein a) the disintegrated slag is leached with stirring with a washing liquor in a first leaching stage at a temperature from 55 to 75 degrees C and a pH value from 9.5 to 12, which pH value is so adjusted that at least part of the SiO2 content of the slag is dissolved, b) the suspension from the first leaching stage is adjusted with stirring at a temperature from 55 to 70 degrees and with introduction of CO2 to a pH value from 9 to 10, which is lower than that in (a), and the residence time in the leaching stage is so adjusted that the SiO2 is substantially precipitated, c) the ratio of washing liquor and slag in (a) and (b) is so adjusted that an Na concentration of at least 100 g/l in the leaching liquor is obtained but the saturation concentration is not reached, d) the suspension from (b) is separated by filtration into residue and filtrate, e) the residue from (d) is washed with water and the amount of water is so adjusted that the filtrate obtained after washing corresponds at most to the leaching liquor which is required in (a), and f) sodium carbonate is recovered from the filtrate from (d).