VERFAHREN ZUR GROSSTECHNISCHEN GEWINNUNG VON METALLOXIDEN, INSBESONDERE VON MAGNESIUMOXID, UND VORRICHTUNG ZUR DURCHFUEHRUNG DES VERFAHRENS

The disclosure is concerned with a process and apparatus for the recovery of metal oxides such as, for example, magnesium oxide from contaminated starting materials such as industrial scale in which the starting material is dissolved in hydrochloric acid to produce a brine which, after concentration, is thermally decomposed to produce metal oxide and hydrogen chloride, waste gas from the thermal decomposition step, and which contains hydrogen chloride, being brought into intimate contact with the brine to effect concentration. The brine to be concentrated is sprayed into a stream of waste gas and at least a proportion of the sprayed brine is resprayed one or more times into waste gas, the amount of brine being resprayed being controlled to maintain the pH value of the concentrated brine produced within a preselected range of values.