Stamenov L.Stefanova V.Lucheva B.Atanasova-Vladimirova S.2024-07-162024-07-162024-07-162024-07-162019-01-011314-79781314-7471SCOPUS_ID:85071160214https://rlib.uctm.edu/handle/123456789/1252The study is focused on the utilization of waste solutions containing a high concentration of ferric ions and sulfuric acid (> 60 g L-1). It is found that the crystallization of ferricopiapite (Fe4.67(SO4)6(OH)2.20H2O), rhomboclase (Fe2(SO4)3. H2SO4.8H2O) and paracoquimbite (Fe2(SO4)3.9H2O) takes place after 70 % evaporation of the solutions and subsequent cooling to a room temperature. With increasing saturation of the solutions (75 % evaporation), the main phases identified in resulting crystals refer to hohmanite (Fe2(OH)2(SO4)2.7H2O) and rhomboclase (Fe2(SO4)3.H2SO4.8H2O). The crystals of paracoquimbite (Fe2(SO4)3.9H2O) and iron hydrogen sulfate hydrate (Fe2(SO4)3.H2SO4.2H2O) are obtained at crystallization temperatures of 100oC and 120oC. The main phases in the crystals change to oxonium iron bis sulfate ((H3O)Fe(SO4)2) and rhomboclase (Fe2(SO4)3.H2SO4.8H2O) with temperature increase to 200°C.enArticle