Ultrasonically assisted acid extraction of manganese from slag

An ultrasonically assisted extraction (UAE) technique was developed for the extraction of manganese from electrolytic manganese slag using a sulfuric acid–hydrochloric acid mixture (4:0.3, v/v) as solvent. The UAE conditions were optimized and the significance of variables affecting UAE tested. The determination of manganese was carried out by atomic absorption spectrophotometry (AAS). The ultrasonic extraction efficiency of manganese can reach about 90% under the following optimum conditions: solvent–slag ratio: 4 mL/g; temperature: 333 K; particle size: 0.2 mm; extraction time: 35 min; amount of additive (citric acid): 8 mg/g slag. During the UAE process, the particle size parameter on the extraction was the most significant, followed by solvent–slag ratio, citric acid mass, time and temperature. The repeatability of UAE technique was satisfactory. The ultrasonic method shown to be a much superior approach to the conventional extraction method in the extraction of manganese from slag.