| 摘要 |
<p><PICT:0967052/C1/1> Zinc values are extracted from blast furnace dust by placing the dust in a series of vats and passing ammoniacal liquid through the vats in series, the extractant, i.e. the ammoniacal liquid, being freed of dust before passing into the next vat, or in the case of the last vat in the series being treated to remove zinc before being recycled to the first vat in the series, while the dust separated from the extractant coming from each vat is treated to recover ammonia which is fed to the first vat. The figure shows a suitable apparatus. Vats 1 to 6 having three compartments equipped with stirrers and containing ammoniacal liquid, e.g. an aqueous solution of ammonia and ammonium bicarbonate are fed with blast furnace dust from lines 7 to 12. The slurry formed passes consecutively through the compartments and into cyclones 16 from which the liquid passes in the case of vats 1 to 5 via line 18 into the next vat and from vat 6 it passes into chamber 19 where it is boiled to precipitate the zinc values which are removed via line 20 whilst the liquid is returned to vat 1 via line 21. The extracted dust passes from cyclones 16 into chamber 22 where it is treated with steam to recover ammonia. The ammonia recovered is returned via line 23 to vat 1.</p> |
