Environmentally friendly disposal of the full components of gold tailings: feldspar recovery and cemented filling

Abstract

ABSTRACT Due to the extremely low-grade of gold in natural ores, a huge amount of gold tailings is produced in the beneficiation progress, which caused the disposal of tailings becomes extremely urgent because of the increasingly stringent environmental protection factors. The present study focuses on the innovative full component disposal of gold tailings, which including the recovery of useful feldspar and safe filling of the remaining low-value component. However, the Fe content of feldspar concentrate is strictly limited, and the Fe removal process is preferred. Firstly, a clean physical (physical-chemical) separation method, magnetic separation, and flotation were combined to remove harmful Fe elements. In addition, Fe removal characteristics of narrow particle size were analyzed. Subsequently, the deslimed gold tailings (+0.045 mm) were used for the recovery of feldspar by flotation in acidic environment. Finally, the ultrafine grained tailings (−0.045 mm), flotation tailing, and iron impurity were backfilled underground by cementation. Separation results show that magnetic field strength and particle size have a significant positive correlation with Fe removal. As the particle size decreases from 0.5–0.25 mm to −0.045 mm, the total Fe content (TFe) increases from 0.23% to 0.35% under 1.4 T field strength, accompanied by the reduction of TFe removal from 68.73% to 61.34%. Flotation can further reduce the TFe to 0.09%–0.21%. Further, feldspar concentrate was successfully recovered with dodecylamine as collector. The grades of Na2O and K2O can reach 7.55% and 3.73% with dosage of 1000 g/t, with recovery of 86.63% and 74.63%. When the tailings pulp concentration is greater than 56%, the curing strength can exceed 0.5 MPa at 3 d. Therefore, feldspar concentrate meeting ceramic standards with whiteness of 58.63 is obtained, and the remaining low value components are filled back to the ground, making it a secondary resource rather than a waste with environmental threats.