| 摘要 |
<p>PROBLEM TO BE SOLVED: To recover bromine in a high yield from a printed substrate as a part of recycle by leaching an incinerated ash dust with water or alkali or acid, neutralizing the leached liq. and filtering the neutralized liq. and absorbing volatiolized bromine obtained by blowing a gaseous chlorine and stream to the filtrate, with an alkali liq. SOLUTION: The incinerated ash dust containing 1-15% bromine is leached with water or an alkali such as sodium hydroxide or potassium hydroxide or an acid such as sulfuric acid, and the leached liq. is subjected to an alkali neutralizing treatment at need and filtered. The filtrate is adjusted to pH 7-8 with alkali, and the liq. is leached for 30-80 min. The leached liq. is filtered to separated to the filtrate and a residue. The leaching ratio of bromine to the filtrate is more than 90%. When the filtrate is stored inside a distillation column, and the filtrate is made to flow down from an upper part and the chlorine and the steam are blown from a lower part of the column, bromine oxidized with chlorine is volatilized with the stream and discharged outside from the upper part of the column. The steam acts a heating function and also works as a carrier gas carrying the volatilized bromine.</p> |
