Mechanochemical Treatment of Historical Tungsten Tailings: Leaching While Grinding for Tungsten Extraction Using NaOH

Abstract

Innovative tungsten (W) extraction techniques are continually being sought because of challenges of low leaching efficiencies, despite using advanced processing units such as autoclaves operating high temperatures and pressures. Compared to conventional leaching, mechanochemical treatment improves the efficiency of leaching. Therefore, in this study, an innovative mechanochemical treatment method, referred to as leaching while grinding (LWG), was employed as a reprocessing option to optimize W recovery from historical tungsten tailings. Experiments were run using the regular two-level factorial design to screen through the four factors of stirrer speed, liquid/solid ratio, temperature, and digestion time to assess their criticality and effects in the LWG process. The stirrer speed and the liquid/solid ratio were the most critical factors in the optimization of W recovery. The maximum W recovery (91.2%) was attained at the highest stirrer speed (410 rpm), low liquid/solid ratio (0.8), long digestion time (6 h), and low leaching temperature (60 °C). The attained low leaching temperature (60 °C) was due to the mechanical activation of scheelite resulting from the simultaneous grinding and leaching. For such low- grade W material, liquid/solid ratio optimizing is critical for maintaining the digestion mixture fluidity, and for environmental and economic sustainability regarding the sodium hydroxide (NaOH) consumption, which was low.

Effect of temperature on the leaching of heavy metals from nickel mine tailings in the arctic area, Norway

“…It takes about 51 weeks to occur acidification process of stacking, indicating that acidification will take a long time. However, low sulfur tailings will not acidify in a short time [41,42] . The acidified tailings have a strong promoting effect on the dissolution of heavy metal ions and salts in the tailings, so that the dissolution concentrations of heavy metals such as Pb, Zn and Cd are increased [43,44] .…”

Reuse and Mechanochemical Processing of Ore Dressing Tailings Used for Extracting Pb and Zn

“…The presence of many exogenous factors influencing the leaching efficiency significantly complicates the formulation of the problem [52,53]. The most important factors are a ratio of H 2 SO 4 and HCl in the leaching solution [54,55], a high-pressure value aimed at intensifying oxidative acid leaching [56,57], and leaching time [58][59][60]. Scientific works analysis [61][62][63][64] showed that in the metals leaching process, the following parameters are the most important: the lixiviant type (H 2 SO 4 , HCl, HNO 3 ); stirring speed; solid-to-liquid (S/L) ratio; acid concentration; temperature; granulometric composition of tailings; leaching time.…”