从废银催化剂中回收银的工艺

Recycling Silver Technology from Waste Silver Catalyst by Silver Acetylide

开发了一种乙炔沉淀法从废银催化剂中回收银的工艺.确定了硝酸溶解废银催化剂中银的工艺条件：硝酸浓度10％、反应温度60℃、反应时间1h、反应次数5次,银的溶解回收率接近100％.采取稀硝酸和碱连续吸收反应生成的NOx尾气,无废气排放.在常温、常压下,以乙炔为Ag＋离子沉淀剂,银离子沉淀率接近100％.在室温条件下,以水合肼还原乙炔银,反应时间为2h.在1 000～1 100℃,以中频感应炉熔炼银粉,熔炼时间为6～8 min.银的回收率为98.3％,纯度为99.89％.

The process of recycling silver from waste silver catalyst through silver acetylide with acetylene was developed.The dissolving conditions of waste silver in nitric acid were as follows：nitric acid concentration 10%,reaction temperature 60 ℃,reaction time 1h,and dissolving reaction for 5times.And under these conditions,silver recovery rate in the dissolution was almost 100%.Exhaust NOxfrom reaction were absorbed continuously by dilute nitric acid and sodium hydroxide solution,and therefore there was no emission in the silver dissolution.At room temperature and atmosphere pressure,silver ion in silver nitrate solution reacted with precipitating agent acetylene to produce silver acetylide,and silver ion precipitation ratio was almost 100%.Hydrazine hydrate as a reductant reacted with acetylide silver for2hours to produce silver powder at room temperature.Silver powder was melted in medium frequency induction furnace at 1 000-1 100℃and 6-8min.Silver recovery rate was 98.3%,and the purity of silver was 99.89%.