Study On Recovery And Cure Treatment Of Heavy Metals In Electroplating Sludge

Electroplating sludge is the product of treatment of electroplating wastewater. There are several heavy metals in electroplating sludge which is typical hazardous waste. Also, it is potential threat to the environment. On the another hand, heavy metals in it are precious resources. The level of electroplating sludge recovery in our country is low. Electroplating sludge often produces serious secondary pollution. In this study, heavy metals in electroplating sludge are transferred into the solution by acid leaching. Heavy metals are removed out of by extraction and fractional capitation. The leaching residue is solidified.This study performed impacts test of different factors on leaching, extraction, precipitation and solidification. The best leaching condition is being leached by vitriol for 30 min at room temperature. And concentration of vitriol is about 2 mol·L-1. Solid-liquid ratio is 1:2. The stirring intensity is 150r·min-1. Extraction rate of iron is 98% when p H value was about 0 by two-stage extraction with P204(33%). Extraction time is about 12 min. The volume ratio is 1:2. The load extracting agent was reused after baci-extraction. Metals like copper, zinc and nickel are precipitated at appropriate end-p H value when the amount of precipitant is enough. The recovery rate is more than 93%. Recovery rate of chromium is about 85%. Purity and crystal type of the product is good. The new solidifying method using gypsum shows good effect to leaching residue. Leaching residue can be directly landfilled. The expansion ratio is low. This method shows good prospects for engineering application.Comprehensive and low-cost recycle of high value heavy metals from electroplating sludge is implemented by this method. The leaching residue is solidified suitably. The method provides a new idea for recovery of electroplating sludge.