Selective separation of magnesium from Slovenian dolomites

Although magnesium is one of the most abundant elements on Earth by weight, the demand for magnesium is constantly increasing due to its widespread use in a diverse range of industries such as metal alloys, electronics, batteries, agricultural and pharmaceutical compounds. For this reason, magnesium is categorised as a critical raw material by the European Union. Dolomite CaMg(CO3)2 is one of the most important mineral sources of magnesium, which in its pure form contains 13.18 % magnesium by weight. Various pyrometallurgical and hydrometallurgical processes have been developed and are used to extract magnesium from dolomite and other magnesium ores. In this study, samples of dolomite of different geological ages were collected in Slovenia and their elemental composition was analysed by microwave-assisted acid digestion and ICP-OES. Magnesium was then extracted by selective leaching and selective precipitation. Leaching was carried out with inorganic and organic acids. The separation of magnesium and calcium in a solution prepared by dissolving dolomite with acid was carried out by precipitation with hydroxide and oxalate. High extraction yields of magnesium and a significant separation between the two metals were achieved with both methods.