The characteristics and resource utilization of chromium-containing electroplating sludge

Chromium (Cr)-containing electroplating sludge is a hazardous solid waste and has a detrimental effect on human health and the environment. The existing mainstream methods still have problems such as high costs and complicated processes. In this study, the composition, phase composition, heavy metal content, microstructure, calcination characteristics, and vitrification of chromium electroplating sludge were analyzed by XRF, XRD, ICP-OES, and SEM. The results showed that calcination of sludge at 650 °C and 850 °C produces magnetic ferrite ZnFe2O4. When solidifying sludge with D245 glass, the maximum sludge addition is 35% in order to make the Cr(VI) leaching concentration meet the national standard. Here, the plastic solidification method was developed to solidify Cr-containing electroplating sludge and fill plastic building templates. This method is simple to operate, low cost, and a promising prospect. The effect of surface modification of electroplating sludge was discussed. The most obvious effect of the modification is sodium stearate, modified by sodium stearate powder oil absorption decreases value from 0.62 g/1.0 g to 0.40 g/1.0 g. When sodium stearate with 1.5% was used as the sludge surface modifier, the contact angle reached 88.98°. Then, the effect of the ratio of PVC to modification sludge on the performance of PVC building templates was investigated and compared with that of the templates prepared by calcium carbonate filling. It was found that the performance of the sludge-filled PVC template was superior to the traditional calcium-carbonate filled PVC template when the ratio of PVC to sludge is 100:150, and the tensile strength reached 15.3233 Mpa and 13.745 Mpa, respectively. Thus, this study demonstrates a new method to treat and recycle Cr-containing electroplating sludge.