This paper presents the extraction of zinc ions from waste resulting from the galvanic industry, such as sludge from acid zinc electroplating baths, and their revaluation in mineral fertilizer as zinc-ammonium phosphate. The purpose of this work is to extract zinc ions from the sludge that forms directly in the zinc bath, which can only contain zinc and small amounts of iron, to revalorize zinc into the form of zinc-ammonium phosphate. The process of obtaining zinc-ammonium phosphate is presented using waste sludge from the galvanic industry. In order to obtain zinc-ammonium phosphate, the solution resulting from the dissolution of the sludge with a 20% hydrochloric acid solution was used in reaction with diammonium phosphate and a 25% ammonia solution. After the chemical analysis of the obtained products, zinc-ammonium phosphate was characterized using X-ray powder diffraction, infrared FT-IR spectroscopy and electronic microscopy (SEM) analysis. The results obtained indicate a promising approach to sustainable resource utilization in the production of zinc-ammonium phosphate.
Keywords: microelement fertilizer; waste sludge; zinc–ammonium phosphate.