Utilization of High-Zn Content Ferrous Landfill Sludge with the Use of Hydrogen

Abstract

Sludge, due to its form and significant moisture and zinc content, is the most problematic metallurgical waste. Near the site of a disused steelworks plant in Krakow (Poland) there is an estimated 5 million tonnes of landfill sludge that consists of more than 90% iron and other metal oxides. There is a global tendency to switch steel production towards carbonless technologies, which is why the presented work investigates the possibility of simultaneous waste liquidation and recovery of valuable metals with the use of hydrogenous reduction. Direct reduced iron (DRI) production was selected as the targeted technology, so the sludge was lumped and bound with cement or CaO addition. The obtained lumps were reduced in a hydrogenous atmosphere with gradual heating to 950 °C, after which their phase structure was analyzed and elemental analysis was performed. It was found that zinc evaporated during the experiment, but mostly thanks to the carbon contained in the sludge. The increased addition of binder to the sludge resulted in the enhancement of the lumps, but also limited the reduction range. The products obtained were mostly wustite and less pure iron. Taking into account the degree of reduction and the lumps’ compression strength, the best binding was achieved by adding cement at a quantity of 5% mass.

Research on the Synthesis of Zinc–Ammonium Phosphate Using Galvanic Waste Sludge as a Source of Zinc

“…The obtained products were subjected to X-ray diffraction analysis. X-ray diffraction was measured with a Shimadzu-600 diffractometer using CuKα radiation [18,19].…”

“…Waste sludge from industry or urban wastewater treatment plants is a source of revalorization of metals and other useful substances [13][14][15][16][17][18][19][20][21]. Galvanic sludges, generated as a byproduct of electroplating processes, contain valuable metals such as zinc, copper, nickel and chromium.…”