Barium slag is a kind of solid waste derived from the carbon reduction process of producing barium salt. Carbon is one of the main components in barium slag with a content of more than 10%. In this study, a barium slag was characterized using XRF, XRD and SEM-EDS, and froth flotation test was introduced to recover the carbon in the barium slag. In the process of froth flotation test, diesel was selected as a collector and terpenic oil was selected as a frother for carbon separation. The flotation influences of pulp pH, collector dosage, frother dosage and flotation time were investigated. The results showed that the obtained carbon concentrate had a carbon grade of 63.25% and its recovery was 82.70% under the conditions of pH 8.50, diesel 600 g/t, terpenic oil 500 g/t, and flotation time 5 min. SEM-EDS analysis results revealed that the flotation concentrate was coarse and its particle sizes had a homogeneous distribution. The findings of this research provide a new pathway for barium slag utilization. The carbon obtained from the flotation test in this study can be recycled as raw materials, while the reduction of the remaining tailings can be utilized as building material additives. (C) 2020 Elsevier Ltd. All rights reserved.