钢厂含锌烟尘强化浸出及铁钾钠分离研究

Enhanced leaching zinc dust from iron-steel plant and separation of iron, potassium and sodium

钢铁厂冶炼过程中产生的含锌烟尘中主要含锌、铁、铟等有价金属,具有较高的回收价值。针对常规中浸-酸浸-高酸浸工艺处理烟尘存在原料适应性差、流程长、渣量大等问题,提出钢厂含锌烟尘中浸氧化沉铁-加压浸出的两段浸出工艺路线,并采用高温铁矾法对铟回收后液中的铁钾钠进行分离。研究结果表明:在液固比为3.9 mL/g、温度为60℃、过氧化氢用量为65 mL/kg、中浸时间1 h以及中和时间2 h的Ⅰ段浸出条件下,锌的浸出率为83.55%,Ⅰ段浸出液中铁的质量浓度仅为3.88 mg/L;在液固比为2.5 mL/g、温度为125℃、浸出时间为3 h的条件下Ⅱ段浸出,锌的浸出率为98.71%。经两段浸出后,锌的总浸出率和回收率分别为99.61%和95.42%,含锌烟尘中锌的质量分数从57.18%降低到0.83%,铅的质量分数由7.31%富集至30.10%;在120~150℃时,促进Fe(Ⅲ)水解生成铁矾,所得铁矾渣品质高,锌、铁、钠和硫质量分数分别为1.97%,30.77%,0.69%和12.52%,沉铁率和沉钾率分别为99.52%和96.57%。钢厂含锌烟尘的两段浸出及高温铁矾沉铁工艺实现了锌的高效浸出、溶液中铁钾钠的高效分离和烟尘的资源化处理。

Zinc dust produced during the smelting process of iron-steel plant contains zinc, iron, indium and other valuable metals with high recovery value. In view of the problems that the poor material adaptability, long process, large amount of slag in zinc dust was leached by neutral leaching-acid leaching-high acid leaching, a novel two-stage leaching process route of zinc dust was developed by oxidation iron precipitation neutral leaching-pressure leaching process, and separation of iron, potassium, sodium from the pressure leaching solution after recovery In by high temperature jarosite. The results show that under the reaction condition of Ⅰ-stage leaching with liquid-solid ratio of 3.9 mL/g, temperature of 60 ℃, H2O_(2)dosage of 65 mL/kg, neutral leaching time of 1 h,neutralization time of 2 h, the extraction of zinc is 83.55%, and the iron concentration is only 3.88 mg/L in Ⅰ-stage leaching solution. The Ⅱ-stage leaching reaction condition is liquid-solid ratio of 2.5 mL/g, temperature of 125 ℃, leaching time of 3 h, and the extraction of zinc in the Ⅱ-stage leaching is 98.71%. After two stage leaching, the total extraction and recovery of zinc are 99.61% and 95.42%, respectively. The mass fraction of zinc decreases from 57.18% to 0.83%, and the mass fraction of lead increases from 7.31% to 30.10%. The high quality of jarosite residue is produced at the range of 120-150 ℃ and promotes the hydrolysis of iron to form jarosite.Under this condition, the main composition(mass fraction) of the high temperature jarosite residue is Zn 1.97%, Fe 30.77%, Na 0.69% and S 12.52%. The precipitation rate is 99.52% and 96.57% for iron and potassium,respectively. The two-stage leaching process of zinc dust and iron precipitation of high temperature jarosite can realize high efficiency leaching of zinc, high efficiency separation of iron, potassium, sodium in solution and resource utilization of dust.