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The direct sulfidization of cuprite is inefficient because cuprite is a copper-oxide mineral with a strong surface hydrophilicity. In this study, oxidant was used to modify cuprite surfaces to regulate the sulfidization of cuprite. Microflotation tests showed that the flotation recovery of pre-oxidized cuprite was nearly 25% higher than that of direct sulfidization flotation, which indicates that the cuprite surface activity was enhanced after pre-oxidation by Cu(I) species (weak affinity with sulfur ions) transformation to Cu(II) species (strong affinity with sulfur ions). Zeta potential, scanning electron microscopy-energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry results showed that pre-oxidation improved cuprite sulfidization and promoted the formation of copper-sulfide species on the cuprite surfaces. The mineral surface stability and thus, xanthate species adsorption on the cuprite surfaces were improved. The surface-adsorption measurements and infrared spectroscopy showed that a large amount of xanthate species was adsorbed onto the sulfidized cuprite surfaces after pre-oxidation, which enhanced the cuprite hydrophobicity and improved the cuprite flotation.

High-power red lasers (mainly at 639 and 670 nm) based on Pr

Copper-lead-zinc mixed ore in Tibet, China, is a complex and refractory polymetallic ore resource; thus, ascertaining its mineralogical properties is very important for comprehensive recovery of valuable elements. In this work, the mineralogical properties of this copper-lead-zinc mixed ore have been characterized in detail following a multidisciplinary approach, including chemical, phase, x-ray diffraction (XRD), electron microprobe, and mineral liberation analyses. The results show that the raw ore contained 0.53% Cu, 1.29% Pb, and 0.54% Zn; the oxidation rates of copper, lead, and zinc were 40.21%, 79.31%, and 84.83%, respectively. The Au and Ag contents in the raw ore were 0.28 g/t and 23.6 g/t, which can be comprehensively utilized along with the recovery of copper, lead, and zinc. The gangue mainly contained SiO2, CaO, and Al2O3. Copper in the raw ore mainly existed in bornite, duftite, chalcopyrite, and chrysocolla; lead mainly existed in cerussite, duftite, and galena; zinc mainly existed in willemite, hemimorphite, and sphalerite. The complexity in the embedding and wrapping relationships, fine-grained dissemination, high oxidation, and considerable differences in the floatability of various minerals result in difficulties in recovering the target minerals using a single method. Based on the systematic mineralogical properties obtained, an integrated technology of “bulk flotation-oxidation roasting-hydrometallurgy” has been proposed to enrich and separate copper, lead, and zinc in the ore, providing new ideas for the comprehensive and efficient utilization of polymetallic mineral resources in Tibet.

In the process of chalcopyrite–pyrite flotation, depression of pyrite is of great significance. In this study, tannic acid (TA) was used to replace traditional inorganic reagents for depression of pyrite under the low-alkalinity condition, and the interaction mechanism of TA with the pyrite surface was studied. Adsorption experiments showed that adsorption of xanthate on the pyrite surfaces was greatly inhibited after treatment with TA, while that of chalcopyrite was only slightly affected. Zeta potential measurements suggested that TA decreased the surface potential of pyrite among pH 3–10. A new characteristic peak appeared in the pyrite–TA infrared spectrum. Time-of-flight secondary-ion mass spectrometry and X-ray photoelectron spectroscopy measurements revealed that Fe atoms were the active sites on the pyrite surface, and they strongly interacted with TA. Microflotation tests confirmed that TA had an obvious depression effect on pyrite, but it had no distinct depression effect on chalcopyrite. These results verified that TA can selectively weaken the floatability of pyrite in Cu–Fe flotation, thereby enabling separation of chalcopyrite from pyrite at low alkalinity.

Titanium(Ti)-bearing electric furnace slag (TEFS) was leached with sulfuric acid in this study. The influence of temperature, acid/solid ratio, particle size, and initial sulfuric acid concentration on the Ti extraction was evaluated. The leaching kinetics indicate that diffusion across the product layer and the interface transfer both affected the decomposition of the TEFS, and the apparent activation energy was24.01 kJ/mol. Reaction temperature was the most important factor that influenced the extraction of Ti, followed by the acid/solid ratio, sulfuric acid concentration, and particle size. The Ti leaching rate reached up to 89.46 % under the conditions of an average particle size of 31.5 μm, acid/solid ratio of 2.0:1, initial acid concentration of 88.0 wt%, reaction temperature of 513.15 K, and water leaching temperature of 333.15 K for 120 min. Fe was almost completely dissolved in the acid, whereas MgO (22.73 wt%) and Al2O3 (44.57 wt%) in spinel were retained in the leach residue, and SiO2 (45.94 wt%) and CaO (34.96 wt%) occurred in the form of diopside in the leach residue. During the leaching process, substantial TiOSO4 and CaSO4·2H2O were produced and coated the TEFS particles, which hindered the leaching of Ti. Keywords: Sulfuric acid leaching, Titanium-bearing electric furnace slag, Kinetics, Mechanism

This paper proposed the surface modification of hemimorphite using lead ions as a promising method for increasing its flotation recovery with sodium oleate as collector. The floatability of lead-modified hemimorphite was significantly improved and the flotation recovery of hemimorphite in the presence of lead ions reached up to 90.3% at 5 × 10−5 mol/L sodium oleate. The experimental results of zeta potential showed that lead ions could adsorb on the hemimorphite surface in the form of Pb2+ and Pb(OH)+, and the adsorbed lead species rendered the hemimorphite surface positively charged at pH Zn O, Si O and OH species. O atoms on the hemimorphite surface interacted with Pb2+ and Pb(OH)+ in the flotation pulp to form a new active product, i.e., O Pb complex through electrostatic interaction and chemical adsorption, which greatly increased the number of reactive sites on the hemimorphite surface. The adsorbed lead species on the mineral surface exhibited strong reactivity towards sodium oleate, so more hydrophobic species were formed on the hemimorphite surface, thus enhancing the floatability of hemimorphite.

This paper proposed a promising method of improving the sulfidization flotation of smithsonite through surface modification with ammonia. The floatability of ammonia-modified smithsonite was superior to that of bare smithsonite under the same flotation condition due to the enhanced sulfidization. Results of zeta potential and surface adsorption experiments showed that the preliminary modification of smithsonite surfaces with ammonia increased the amount of sulfide ion species adsorbed onto the mineral surface, thereby facilitating the attachment of xanthate species onto the sulfidized mineral surface and promoting its hydrophobicity. XPS measurement revealed that surface modification with ammonia prior to Na2S addition increased the amounts of zinc sulfide species formed on the mineral surface and altered the chemical environment of sulfidization products. Furthermore, the activation mechanism of ammonia modification for enhancing the adsorption of sulfide species onto the smithsonite surface was studied by solution chemistry calculations. Zinc ammonia complexes were found to interact with hydrophilic species coated on the smithsonite surface. This interaction increased the number of zinc sites on the surface of ammonia-modified smithsonite and thus enhanced its sulfidization flotation.

Copper-oxide raw ore has a complex composition and cannot be processed effectively by conventional, single-stage sorting methods. Based on the characteristics of copper-oxide ore, a new combined grinding–flotation–high-gradient magnetic separation–secondary grinding–leaching process has been proposed to recover copper. Test results show that the new process is very effective. Sodium sulfide was used as a vulcanizing agent in the flotation process, and butyl xanthate was used as a collector to obtain a qualified copper concentrate with a copper grade of 29.37% and a recovery rate of 32.22%. The flotation tailings were subjected to high-gradient magnetic separation to obtain magnetic concentrates and magnetic tailings, and copper was recovered by leaching from the magnetic concentrates and tailings. After secondary grinding of the magnetic concentrates, the leaching rates of copper from the magnetic concentrates and magnetic tailings were 26.85% and 26.95%, respectively. The total copper recovery was 86.02%. The new process introduces high-gradient magnetic separation, enriches refractory chrysocolla, leaches chrysocolla at 65 °C, leaches malachite from the magnetic tailings at 40 °C, and saves heating costs. Secondary grinding can reduce the leaching temperature, shorten the leaching time, and achieve a low energy consumption and effective extraction of refractory copper-oxide ore.

Sulfide hemimorphite can be depressed by Fe3+ during flotation. In this study, the depression mechanism was studied by microflotation, inductively-coupled plasma mass spectrometry, local electrochemical impedance spectroscopy (LEIS), and X-ray photoelectron spectroscopy (XPS). Flotation test results suggested that sulfated hemimorphite can be depressed by Fe3+ across the entire pH range. LEIS, adsorption analysis, and XPS indicated that S species were adsorbed on hemimorphite as ZnS. The sulfide film was attenuated and no adsorbed Fe species were found after treatment with Fe3+. The results indicate that Fe3+ reacts with the ZnS film, which decreases the number S species, and this leads to hemimorphite depression.

Titanium-bearing electric furnace slag (TEFS) was prepared from vanadium titanomagnetite and leached with sulfuric acid. The Ti leaching rate of vanadium titanomagnetite TEFS is significantly lower than that of ilmenite TEFS. The impurity content in vanadium titanomagnetite TEFS is higher than that in ilmenite TEFS. This might be one of the main factors resulting in the low leaching rate of Ti, so the leaching behaviors of various impurities under different conditions (temperature, acid/solid weight ratio, particle size, and initial sulfuric acid concentration) were investigated. The following trends were observed under different leaching conditions: The leaching rate of Fe increased rapidly and reached equilibrium quickly, that of Si increased quickly in the early stage and then decreased in the later stage, that of Ca increased initially and reached equilibrium later, and the leaching rates of Mg and Al increased gradually until the equilibrium was reached. The leaching rate of Fe was too rapid to be able to investigate its leaching kinetics, and the insoluble leached products of Si and Ca interfered with their leaching. The effects of leaching parameters on the leaching of impurities were further analyzed by X-ray diffraction (XRD) and scanning electron microscopy analysis. XRD data indicated that spinel is the major Mg- and Al-bearing mineral in TEFS. Mg and Al showed similar leaching behaviors, and their leaching conformed to a new model based on interface transfer and diffusion across the product layer, both of which affect the leaching rate.

Pr3+:YLF crystal has been demonstrated as a successful laser gain medium in the visible region. However, the 604-nm laser based on this crystal is limited in power due to the intrinsic reabsorption in the orange region. We propose a laser diode (LD) pumped continuous-wave (CW) 604-nm laser based on a lowly-doped Pr3+:YLF crystal. A maximum output power of 3.28 W with a total slope efficiency of 34.2% is achieved at 604 nm. The slope efficiency increases to 43.0% under high-power pumping conditions. To the best of our knowledge, the output power of the 604-nm laser we achieved is the highest to date and no output power saturation is observed. Besides, dual-wavelength operations at 604 and 607 nm are achieved by tuning the thermal lensing effects of the crystal, without any additional wavelength-selection elements. The dual-wavelength laser at 604 and 607 nm with a maximum output power of 3.30 W (highest to date as well) is obtained by this approach. Since no extra intracavity losses are introduced by intracavity wavelength-selection elements, the method we proposed will be promising to obtain high-power wavelength-switchable lasers.

Water used by mining enterprises needs to be comprehensively recovered and utilized to achieve clean production. This requires the effective treatment of mineral processing wastewater. Wastewater produced during non-ferrous metal mineral processing contains a complex mixture of pollutants at high concentrations, making comprehensive treatment difficult. Here, the sources of and hazards posed by wastewater produced during non-ferrous metal mineral processing are introduced and the techniques for removing heavy metal ions and organic chemicals are reviewed. Chemical precipitation and adsorption methods are often used to remove heavy metal ions. Chemical precipitation methods can be divided into hydroxide and sulfide precipitation methods. Organic chemicals are mainly removed using oxidation methods, including electrochemical oxidation, photocatalytic oxidation, and ultrasonic synergistic oxidation. External and internal cyclic utilization methods for treating wastewater produced by mineral processing plants are introduced, and a feasibility analysis is performed.

Metal ions are unavoidable in pulp solution, and they frequently influence the flotation recovery of minerals, such as by activation or depression. In this work, we systematically investigated the adsorption characteristics of Cu2+ species on cerussite surfaces and the concomitant effect on sulfidization flotation by micro-flotation experiments and surface analysis. The flotation results indicated that the flotation recovery of cerussite was almost unchanged at low Cu2+ concentration in the presence of Na2S, but it decreased at high Cu2+ concentration. X-ray photoelectron spectroscopy indicated that CuCO3 species formed on cerussite surface in the presence of Cu2+, and Pb–S species and Cu–S species formed after Cu2+–Na2S treatment. Time-of-flight-secondary-ion mass spectrometry indicated that the distribution of lead species narrowed and that of copper species broadened with increasing Cu2+ concentration, which demonstrated that Cu2+ covered the mineral surfaces and inherent Pb2+ was shield. Ultraviolet–visible spectroscopy indicated that the stability of cerussite surface increased with increasing amount of added Na2S. Compared with only Na2S treatment, consumption of xanthate was almost unchanged at low Cu2+ concentration, whereas consumption of xanthate considerably increased at high Cu2+ concentration, which may be because xanthate was consumed by the residual copper ions in the pulp solution. Zeta potential measurements indicated that Cu2+ can chemisorb on cerussite surfaces and increasing the Cu2+ concentration facilitates adsorption of copper species, but it inhibits adsorption of Na2S and BX. Therefore, sulfidization flotation of cerussite is not substantially affected by low concentrations of Cu2+, but is greatly affected by high concentrations of Cu2+.

Separation of chalcopyrite from galena in a low-alkaline environment is a critical technological process. This study explores the mechanism of the selective flotation depression effect of locust bean gum (LBG) toward galena. This natural polymer is applied for the first time to improve the selectivity of chalcopyrite/galena flotation. After the addition of 5-mg/L LBG at pH 8.0, the recovery of galena using sodium butyl xanthate as a collector drops below 10%, whereas the recovery of chalcopyrite remains over 80%. The selectivity of LBG toward galena is further characterized by adsorption tests, zeta potential measurements, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry. The interaction mechanism that drives the adsorption process may be the hydrogen bonding between the hydroxylated mineral surface acting as a Bronsted acid and –OH groups from LBG polymer acting as a Bronsted base.

The interaction behavior and mechanism of magnesium ions with cassiterite and quartz surfaces and their effects on flotation separation of cassiterite from quartz were investigated by micro-flotation tests, surface adsorption experiments, zeta potential measurements, solution chemistry calculation, and X-ray photoelectron spectroscopy (XPS) analysis. The micro-flotation tests showed that solution pH significantly affected the floatability of cassiterite and quartz in the absence and presence of magnesium ions, and the preferred flotation separation of cassiterite from quartz was obtained at pH 6.8–8.2. Adsorption experiments and zeta potential measurements indicated that magnesium ions significantly affected the adsorption of sodium oleate on the mineral surface. The effect gradually aggravated with increasing pH due to the specific adsorption of hydrated Mg(OH)+ and Mg(OH)2 on the mineral surface. The adsorption mechanism of magnesium species onto the mineral surface was ascertained by XPS measurement. Magnesium species were adsorbed onto the mineral surface through interaction with the O sites of cassiterite and quartz particles, and a strong interaction occurred in the solution with high pH.

The dissolution kinetics of lead-bearing ore in trichloroacetic acid (TCA) solution were investigated. The effects of various parameters were studied to optimize the dissolution conditions and to d...