Effect mechanism of carbonaceous materials on the flotation separation of lead–zinc ore

[Display omitted] •Carbon pre-flotation can improve the grade and recovery of lead.•Amorphous carbon accounts for 99.70% of total carbon in the concentrate.•Amorphous carbon has rich aromatic rings, carbonyl and hydrocarbyl.•The adsorption capacity of the amorphous carbon for diethyl dithiocarbamate was superior to that of galena. The associated carbonaceous material in ore will deteriorate the flotation process. However, only a few studies have been conducted on the properties of carbonaceous materials in lead–zinc ore flotation. The properties and adsorption performance of carbonaceous materials remain unclear. In this study, the closed-circuit flotation of bench-scale experiments shows that carbon pre-flotation can improve the grade and recovery of lead. The properties of the enriched carbonaceous materials were analysed. Amorphous carbon accounts for 99.70% of the total carbon in the concentrate. The structure of amorphous carbon is similar to the properties of coal, which has rich aromatic rings, carbonyl, and hydrocarbyl. Moreover, amorphous carbon has abundant pore structures with a specific surface area of 16.18 m2/g and an average pore diameter of 12.94 nm. The adsorption isotherm of diethyl dithiocarbamate (DDTC) onto amorphous carbon fits the Freundlich model well. The pseudo-second-order (PSO) model can better interpret the adsorption process. The adsorption capacity of amorphous carbon for DDTC is superior to that of galena, leading to the depletion of DDTC in the flotation pulp.