Recovering Volatilized Salts from MSWI Fly Ash into\nDifferent Metal Species with High Purifies

Thermal\nsintering/melting technology is a hot topic for the treatment\nof municipal solid waste incineration with fly ash (FA) nowadays.\nMost attention is focused on the safety of the treated FA, but seldom\nfocus is put on the separation of thermally volatile metal salts.\nIn this work, we investigated a thermal-sediment control method for\neffective separation of Zn, Pb, Cu, Cd, K, and Na from FA. Volatilized\nsolids collected from different sediment zones (according to their\ndistances from the FA source) are compared in detail under controlling\ngas flow rates and heating temperatures. As a result, 52 wt % of Cd\nand 54 wt % of Pb are first separated in different zones, and 53 wt\n% of Zn and 52 wt % of Cu are second separated in different zones.\nFinally, Na and K are recovered together. Pb and Zn purities are as\nhigh as 93–94 wt %. What is more, recovery rates of metals\nfrom FA follow the order of 90 wt % (Pb) > 83 wt % (Zn) > 81\nwt %\n(Cd) > 77 wt % (Cu) > 73 wt % (Na) > 66 wt % (K). A volatilization-condensation\nmechanism is put forward to explain the separation of different metal\nsalts. The main result of this work helps the development of the “zero-waste\ncity” concept, which is also in favor of green development\nand circular economy.