The flotation of low-grade manganese ore using a novel linoleate hydroxamic acid

Unlocking the potential of sulphide tailings: A comprehensive characterization study for critical mineral recovery

Sulphide tailings are a major environmental concern due to acid mine drainage and heavy metal leaching, with costly treatments that lack economic benefits. Reprocessing these wastes for resource recovery can address pollution while creating economic opportunities. This study aimed to evaluate the potential for critical mineral recovery by characterizing sulphide tailings from a Zn-Cu-Pb mining site. Advanced analytical tools, such as electron microprobe analysis (EMPA) and scanning electron microscopy (SEM)-based energy dispersive spectroscopy (EDS), were utilized to determine the physical, geochemical, and mineralogical properties of the tailings. The results showed that the tailings were fine-grained (∼50 wt% below 63 μm) and composed of Si (∼17 wt%), Ba (∼13 wt%), and Al, Fe, and Mn (∼6 wt%). Of these, Mn, a critical mineral, was analyzed for recovery potential, and it was found to be largely contained in rhodochrosite (MnCO₃) mineral. The metallurgical balance revealed that ∼93 wt% of Mn was distributed in -150 + 10 μm size fractions containing 75% of the total mass. Additionally, the mineral liberation analysis indicated that Mn-grains were primarily liberated below 106 μm size, suggesting the need for light grinding of above 106 μm size to liberate the locked Mn minerals. This study demonstrates the potential of sulphide tailings as a source for critical minerals, rather than being a burden, and highlights the benefits of reprocessing them for a resource recovery to address both environmental and economic concerns.

A critical review on approaches for electrolytic manganese residue treatment and disposal technology: Reduction, pretreatment, and reuse

Electrolytic manganese residue (EMR) has become a barrier to the sustainable development of the electrolytic metallic manganese (EMM) industry. EMR has a great potential to harm local ecosystems and human health, due to it contains high concentrations of soluble pollutant, especially NH₄⁺ and Mn²⁺, and also the possible dam break risk because of its huge storage. There seems to be not a mature and stable industrial solution for EMR, though a lot of researches have been done in this area. Hence, by fully considering the EMM ecosystem, we analyzed the characteristics and eco-environmental impact of EMR, highlighted state-of-the-art technologies for EMR reduction, pretreatment, and reuse; indicated the factors that block EMR treatment and disposal; and proposed plausible and feasible suggestions to solve this problem. We hope that the results of this review could help solve the problem of EMR and thus promote the sustainable development of EMM industry.

Adsorption Behavior and Wettability of Rhodochrosite Surface: Effect of C18 Fatty Acid Unsaturation

Mineral surface wettability and its regulation by the adsorption of collectors have an important influence on the flotation performance. The adsorption behavior of C18 fatty acid with different unsaturation and its effect on rhodochrosite wettability was investigated with surface tension, contact angle, and atomic force microscopy (AFM) measurements. The results indicated that rhodochrosite hydrophobicity increased with the increasing concentration of fatty acid, along with the maximum contact angle (θmax) between hemimicelle concentration (HMC) and critical micelle concentration (CMC). Oleic acid (OA), linoleic acid (LA), and α-linolenic acid (ALA) had a higher θmax than stearic acid (SA), but the value decreased with the increase of C=C bond number. Besides, preferential adsorption of unsaturated fatty acids on the liquid-air interface can be attributed to the molecule’s steric hindrance resulting from C=C double bond, and the θ kept almost invariant with a higher value of ΓLG than ΓSL until HMC. The oriented monolayer and bilayer structure of fatty acids formed gradually on rhodochrosite surface with increasing concentration. However, the θmax may not necessarily correspond to the beginning of bilayer formation. Cylindrical monolayer and bilayer micelles of SA molecules were observed on rhodochrosite surface at HMC and CMC, respectively. While bilayer structures of unsaturated fatty acids formed before complete coverage of monolayer on rhodochrosite surface because of surface heterogeneity. This work provided a good understanding on the adsorption mechanism of fatty acid on rhodochrosite for flotation.

Removal of sodium oleate from synthetic manganese leaching solution by coagulation-dissolved air flotation

The coagulation-dissolved air flotation for removal of sodium oleate (NaOL) from synthetic manganese leaching solution was focused in this study. It indicates that partially hydrolyzed polyacrylamide (HPAM), NaOL dosage and pH have a multiple effect on the removal efficiency of NaOL. The results represents a significant removal efficiency of 97.6% NaOL was achieved under the optimal conditions of coagulation-dissolved air flotation by dosage of 20 mg/L HPAM and 30 mg/L NaOL, pH 8.0. Solution pH has a significant effect on the distribution of oleate species and Mn²⁺ species. The addition of HPAM facilitates the formation of OL^- micelle and the decrease of critical micelle concentration (CMC). Oleate species primarily exist, containing Mn(OL)_2(s), OL^- and HOL_(aq). HPAM could cause the Zeta potential of NaOL to shift negatively. HPAM could decrease CMC of NaOL and lead to a transition from three dimensional network structure to lamellar structure. NaOL can be removed by coagulation-dissolved air flotation through the adsorption and bridge effect of HPAM chains on the floating bubble surface.

Recent experimental advances for understanding bubble-particle attachment in flotation

Bubble-particle interaction is of great theoretical and practical importance in flotation. Significant progress has been achieved over the past years and the process of bubble-particle collision is reasonably well understood. This, however, is not the case for bubble-particle attachment leading to three-phase contact line formation due to the difficulty in both theoretical analysis and experimental verification. For attachment, surface forces play a major role. They control the thinning and rupture of the liquid film between the bubble and the particle. The coupling between force, bubble deformation and film drainage is critical to understand the underlying mechanism responsible for bubble-particle attachment. In this review we first discuss the advances in macroscopic experimental methods for characterizing bubble-particle attachment such as induction timer and high speed visualization. Then we focus on advances in measuring the force and drainage of thin liquid films between an air bubble and a solid surface at a nanometer scale. Advances, limits, challenges, and future research opportunities are discussed. By combining atomic force microscopy and reflection interference contrast microscopy, the force, bubble deformation, and liquid film drainage can be measured simultaneously. The simultaneous measurement of the interaction force and the spatiotemporal evolution of the confined liquid film hold great promise to shed new light on flotation.

Immobilization of Mn and NH4 (+)-N from electrolytic manganese residue waste

The objective of this work was the immobilization of soluble manganese (Mn) and ammonium nitrogen (NH4 (+)-N) leached from electrolytic manganese residue (EMR). Immobilization of Mn was investigated via carbonation using carbon dioxide (CO2) and alkaline additives. NH4 (+)-N immobilization was evaluated via struvite precipitation using magnesium and phosphate sources. Results indicated that the immobilization efficiency of Mn using CO2 and quicklime (CaO) was higher than using CO2 and sodium hydroxide (NaOH). This higher efficiency was likely due to the slower release of OH(-) during CaO hydrolysis. The immobilization efficiency of Mn was >99.99 % at the CaO:EMR mass ratio of 0.05:1 for 20-min reaction time. The struvite precipitation of NH4 (+)-N was conducted in the carbonated EMR slurry and the immobilization efficiency was 89 % using MgCl2 · 6H2O + Na3PO4 · 12H2O at the Mg:P:N molar ratio of 1.5:1.5:1 for 90-min reaction time. A leaching test showed that the concentrations of Mn and NH4 (+)-N in the filtrate of the treated EMR were 0.2 and 9 mg/L, respectively. The combined immobilization of Mn and NH4 (+)-N was an effective pretreatment method in the harmless treatment of the EMR.