Enhanced sulfidation xanthate flotation of malachite using ammonium ions as activator

Exchanging Anion in CuCo-Carbonate Double Hydroxide for Faradaic Supercapacitors: A Case Study

A systematic synthetic method involving the anion exchange process was designed and developed to fabricate the superior functioning three-dimensional (3-D) urchin-architectured copper cobalt oxide (CuCo₂O₄; CCO) and copper cobalt sulfide (CuCo₂S₄; CCS) electrode materials from copper-cobalt carbonate double hydroxide [(CuCo)₂(CO₃)(OH)₂; CCH]. The effective tuning of chemical, crystalline, and morphological properties was achieved during the derivatization process of CCH, based on the anion exchange effect and phase transformation without altering the 3-D spatial assembly. Benefiting from morphological and structural advantages, CCO and CCS exhibited superior electrochemical activity with capacity values of 1508 and 2502 C g^-1 at 10 A g^-1 to CCH (1182 C g^-1 at 10 A g^-1). The thermal treatment of CCH has generated a highly porous nature in nanospikes of 3-D urchin CCO structures, which purveys betterment in electrochemical phenomena than pristine smooth-surfaced CCH. Meanwhile, the sulfurization reaction induced the anion effect to a greater extent in the CCS morphology, resulting in hierarchical 3-D urchins formed by 1-D nanospikes constituting coaxially swirled 2-D nanosheets with high exposure of active sites, specific surface areas, and 3-D electron/ion transportation channels. The asymmetric supercapacitor was constructed with a superior CCS electrode as a cathode and an activated carbon electrode as an anode, showing a high specific capacity of 287.35 C g^-1 at 7 A g^-1 and durability for 5000 cycles with 94.2% retention at a high current density of 30 A g^-1. The ultrahigh energy and power density of 135.3 W h kg^-1 (10 A g^-1) and 44.35 kW kg^-1 (30 A g^-1) were harvested during the PC device performance. Our finding proposes an idea about the importance of anions and phase transformation as a versatile tool for engineering high-functioning electrode materials and their endeavor toward overwhelming the major demerit of SCs by aggrandizing the energy density value and rate performance.

N-Alkylated Chitin Nanocrystals as a Collector in Malachite Flotation

The majority of reagents currently used in mineral flotation processes are fossil-based and potentially harmful to the environment. Therefore, it is necessary to find environmentally-friendly alternatives to reduce the impact of mineral processing activities. Chitin nanocrystals are a renewable resource that, due to the natural presence of amino groups on its surface, represents a promising collector for various minerals of economic relevance. This study examines the one-pot functionalization of chitin nanocrystals with aldehyde structures to obtain hydrophobized colloids suitable for mineral flotation. The chemical properties of these nano-colloids were investigated by nuclear magnetic resonance spectroscopy, their colloidal behavior and structure by electrophoretic light scattering and atomic force microscopy, and their wettability through water contact angle measurements. The functionalized N-alkylated chitin nanocrystals possessed a hydrophobic character, were able to dress mineral particles and featured a performance in the flotation of malachite similar to commercial collectors, which proves the high potential of chitin nanocrystals in this field of application.

Estimation and Improvement of Recovery of Low Grade Copper Oxide Using Sulfide Activation Flotation Method Based on GA–BPNN

Copper oxide ore is an important copper ore resource. For a certain copper oxide ore in Yunnan, China, experiments have been conducted on the grinding fineness, collector dosage, sodium sulfide dosage, inhibitor dosage, and activator dosage. The results showed that, by controlling the above conditions, better sulfide flotation indices of copper oxide ore are obtained. Additionally, ammonium bicarbonate and ethylenediamine phosphate enhanced the sulfide flotation of copper oxide ore, whereas the combined activator agent exhibited a better performance than either individual activator. In addition, to optimize all of the conditions in a more reasonable way, a combination of the 5-11-1 genetic algorithm and back propagation neural network (GA–BPNN) was used to set up a mathematical optimization model. The results of the back propagation neural network (BPNN) model showed that the R2 value was 0.998, and the results were in accordance with the requirement model. After 4169 iterations, the error in the objective function was 0.001, which met the convergence requirements for the final solution. The genetic algorithm (GA) model was used to optimize the BPNN model. After 100 generations, a copper recovery of 87.62% was achieved under the following conditions: grinding fineness of 0.074 mm, which accounted for 91.7%; collector agent dosage of 487.7 g/t; sodium sulfide dosage of 1157.2 g/t; combined activator agent dosage of 537.8 g/t; inhibitor dosage of 298.9 g/t. Using the combined amine and ammonium salt to enhance the sulfide activation efficiency, a GA–BPNN model was used to achieve the goal of global optimizations of copper oxide ore and good flotation indices were obtained.

Reexamining the Role of Ammonium Ions in the Sulfidization, Xanthate-Flotation of Malachite

Ammonium ions have positive effects on the sulfidization flotation of malachite; however, the underlying mechanisms remain poorly understood. In the present work, micro-flotation tests, field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and solution analysis for ammonium nitrogen were carried out. The flotation results showed positive effects of ammonium on the sulfidization flotation of malachite. Macroscopically, the sulfidized malachite produced with ammonium exhibited a darker color than that without ammonium, whereas the opposite appeared to be true for their corresponding residual liquids. FESEM images highlighted the larger particle size and higher converge density of the sulfidization product when the presence of ammonium. Furthermore, XPS results indicated a higher sulfur concentration on malachite surfaces when the presence of ammonium. XRD results showed that Cu31S16 (djurleite) and Cu7S4 (anilite) comprised the sulfidization products, regardless of the presence or absence of ammonium. However, neither EDS nor XPS analysis showed nitrogen on malachite surfaces; moreover, the residual-ratio results for ammonium nitrogen clearly demonstrated that most ammonium continued to be held in solution before and after malachite sulfidization. Based on these findings, we inferred that ammonium ions may mediate the nucleation and growth of sulfidization product during malachite sulfidization, rendering larger sulfidization product particles. The larger size of sulfidization products may result in a darker, stabler and denser sulfidization product coating layer, and then may reduce the generation of colloidal copper sulfide in the residual liquids. Ultimately, ammonium facilitates better performance of sulfidization flotation of malachite.

Recovering Cobalt and Sulfur in Low Grade Cobalt-Bearing V–Ti Magnetite Tailings Using Flotation Process

There is 0.032% cobalt and 0.56% sulfur in the cobalt-bearing V–Ti tailings in the Panxi Region, with the metal sulfide minerals mainly including FeS2, Fe1−xS, Co3S4, and (Fe,Co)S2, and the gangue minerals mainly including aluminosilicate minerals. The flotation process was used to recover cobalt and sulfur in the cobalt-bearing V–Ti tailings. The results showed that an optimized cobalt–sulfur concentrate with a cobalt grade of 2.08%, sulfur content of 36.12%, sulfur recovery of 85.79%, and cobalt recovery and 84.77% were obtained by flotation process of one roughing, three sweeping, and three cleaning under roughing conditions, which employed pulp pH of 8, grinding fineness of < 0.074 mm occupying 80%, flotation concentration of 30%, and dosages of butyl xanthate, copper sulfate, and pine oil of 100 g/t, 30 g/t, and 20 g/t, respectively. Optimized one sweeping, two sweeping, and three sweeping conditions used a pulp pH of 9, and dosages of butyl xanthate, copper sulfate, and pine oil of 50 g/t, 15 g/t, 10 g/t; 25 g/t, 7.5 g/t, 5 g/t; 20 g/t, 5 g/t, 5 g/t, respectively. Optimized one cleaning, two cleaning, and three cleaning condition dosages of sodium silicate of 200 g/t, 100 g/t, 50 g/t, respectively. Study of analysis and characterization of cobalt–sulfur concentrate by X-ray diffraction (XRD), automatic mineral analyzer (MLA), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) showed that the main minerals in cobalt–sulfur concentrate are FeS2, Co3S4 and (Fe,Co)S2, of which FeS2 and (Fe,Co)S2 accounted for 65.64% and Co3S4 for 22.64%. Gangue minerals accounted for 11.72%. The element Co in (Fe,Co)S2 is closely related to pyrite in the form of isomorphism, and the flotability difference between cobalt and pyrite is very small, which makes it difficult to separate cobalt and sulfur. Cobalt–sulfur concentrate can be used as raw material for further separation of cobalt and sulfur in smelting by pyrometallurgical or hydrometallurgical methods.

Confirmation of Interlayer Sulfidization of Malachite by TOF-SIMS and Principal Component Analysis

In this work, a sulfidization mechanism of malachite was confirmed based on the depth profile product, principal component, and depth profile curve analyses of time-of-flight secondary ion mass spectrometry (TOF-SIMS). The results showed that Cu/S species, including fragment ion peaks of Cu2S+, Cu3S+, S−, HS−, S2−, CuS2−, and CuS3−, were present in the inner layers of sulfidized malachite in the positive and negative spectral ranges 75–400 and 30–470 m/z. Na2S reacted with the surface and inner atoms, causing simultaneous sulfidization of malachite on the surface and in the inner layers. The inner layer mainly contained positive fragment ions with large Cu/S ratios. In summary, the interlayer sulfidization phenomenon was confirmed and the differences in sulfidization products between the surface and inner layers were determined.