Abstract This study evaluates the effectiveness of mineral concentration techniques, gravimetry and flotation, for the remediation of metallurgical waste with the presence of metal sulfides, mainly galena (PbS). Analysis of the Federico mine (La Carolina, Spain) flotation tailings dam's geology and geophysics revealed its formation, internal structure, and resistivity/chargeability variations tied to moisture and metal content. Although the concentration methods used were efficient, residues maintain high metal levels. Samples collected on the slope of the dam contained up to 9,140 mg kg −1 Pb, 147 mg kg −1 As, 3,920 mg kg −1 Mn and 197 mg kg −1 Zn. The old flotation residue was treated in a hydrocyclone before being taken to the spiral classification process, where a significant amount of Pb (up to 17,700 mg kg −1 ) was eliminated in the overflow. The underflow (4,870 mg kg −1 Pb) was processed in a spiral classifier, generating heavy (221,000 mg kg −1 Pb), mixed (8,050 mg kg −1 Pb), and light (2,840 mg kg −1 Pb) flows. The light fraction obtained from the spiral classifier, with a Pb concentration of 2,840 mg kg⁻ 1 , is comparable to the maximum reference level established by Andalusian legislation for contaminated soils (2,750 mg kg⁻ 1 for industrial land). In terms of mass distribution, this light stream represents 77.91% of the spiral treatment and 72.82% of the total processed material, and could be redeposited at a previously conditioned site, eliminating the environmental risk. Instead, the Pb-enriched streams may be potentially valorisable depending on economic and metallurgical conditions. Froth flotation tests were conducted on the original flotation tailings for comparison purposes. The flotation test yielded a float with 46,700 mg kg −1 Pb (15.49% of total) and a sink with 6,500 mg kg −1 Pb (84.50% of total), this value exceeding Andalusian soil legislation's maximum reference level.
Martínez et al. (Thu,) studied this question.