Ultrafast Carbothermal\nProcess of Municipal Solid\nWaste Incineration Fly Ash for Purification and Valuable Elements\nRecovery

Municipal solid waste incineration fly ash (MSWI FA),\ncontaining\nheavy metals and dioxins that can migrate and accumulate in the biosphere,\nis harmful to human health and the environment. Thermal treatment\ncan effectively purify MSWI FA, but it is not widely used due to high\nenergy consumption and long calcination time. Herein, we report an\nultrafast carbothermal process to heat ash to 3600 °C within\n0.03 s for FA purification and valuable elements recovery. After one\ntime of ultrafast heating, 99.91% of the dioxins were removed, and\nthe purified ash met the leaching standards. After three ultrafast\nheating cycles, the removal efficiencies of heavy metals were up to\n71% for Zn, 86% for Pb, 71% for Cu, 62% for As, 100% for Hg, 93% for\nCd, and 70% for Ni. The ultrafast carbothermal process also promoted\nchlorine removal by an ash washing process due to the decomposition\nof CaClOH. The condensate of volatiles was a good urban mining resource,\nhigher than the minimum industrial grade of ore deposit. Compared\nwith the traditional carbothermal treatment, it consumed only 1/110\nof energy and needed 1/1920 of the furnace volume. The ultrafast carbothermal\nprocess provides an efficient and environmentally friendly way for\nFA purification and valuable elements recovery.