Minerals Engineering最新文献

Iron grain growth during deep reduction roasting is important for iron enrichment from copper slag (CS) through magnetic separation. In this work, a novel method of additive-free activation roasting, including oxidation and subsequent reduction roasting, was proposed to increase the iron grain size, then the iron was extracted by magnetic separation. The phase transformation of CS during activation roasting was studied by TG, XRD, SEM, and EDS. Results showed that the main mineral of fayalite in CS was decomposed into iron oxides and silica during oxidation roasting, and the thickness of iron oxide layer on the particle surface increased with the oxidation temperature. During reduction roasting, the CS and oxidized copper slag (OCS) were ultimately converted into metallic iron and cristobalite solid solution. In the reduced product obtained at 1150 °C, the iron grain sizes were 6.42 μm and 16.62 μm from CS and OCS-1100 °C, respectively. Furthermore, the Fe content in the magnetic concentrate was 72.86 % in the reduced product of CS while that was 87.85 % in the reduced product of OCS-1100 °C with an Fe recovery of ∼ 85 %. This study opens a new direction for iron enrichment from copper slag.

Vanadium-bearing titanomagnetite (VTM) is a crucial source for vanadium production. Conventional methods for recovering vanadium from VTM involving combined pyro- and hydrometallurgy (production of vanadium-rich slag, followed by leaching) or direct leaching encounter significant challenges, such as vanadium losses and complexities in metal separation stage. This study proposes an innovative approach for vanadium extraction from VTM through one-stage leaching and solvent extraction (SX), utilizing an acidic organophosphorus extractant, di(2-ethylhexyl)phosphoric acid/D2EHPA, as the lixiviant. Initial assessment demonstrated the viability of D2EHPA for treating vanadium oxide (V₂O₅) and iron oxides (only Fe²⁺-containing oxides like Fe₃O₄ and FeO). Notably, the addition of a small amount of water had a significant impact on iron extraction. The study investigated the effects of parameters, including the amount of added water, stirring speed, D2EHPA concentration, temperature, time, and pulp density on the vanadium and iron extraction from VTM. The optimal conditions were applied to treat roasted/oxidized VTM. The findings were corroborated through analysis of the resultant loaded D2EHPA using appropriate techniques such as FTIR and UV–Vis spectroscopy. The practicability of the proposed method for treating VTM concentrate on a larger scale was demonstrated by conducting up-scaled tests. Additionally, the separation of vanadium from iron the loaded D2EHPA was explored using selective stripping with H₂SO₄ solution. The recyclability of D2EHPA, a critical factor for sustainability, was investigated through five cycles of extraction-stripping.

Global mineral demand is forecast to increase significantly to achieve the transition to renewable energy. Greater volumes of ore of lower grade will have to be mined to meet demand. Techniques to process large volumes of low-grade ore efficiently are being investigated to reduce the cost and impact of mining. One technique is to use sensor information to sort mined material, allowing waste to be discarded early in mineral processing. Prompt gamma neutron activation analysis (PGNAA) is a sensing technique that can provide information on the multi-elemental composition of a bulk sample which can be used for bulk material sorting. This paper presents the development of a Monte Carlo simulation model of a PGNAA sensor for bulk sorting using the Geant4 toolkit. The GEOSCAN sensor (Scantech Australia) was used as a case-study to demonstrate the application of the model. The sensor responses for a range of pure mineral samples (Fe₂O₃, SiO₂, S, Na₂CO₃ and MnO₂) were measured to validate the developed model. The sensitivity of the simulation results to the hadronic and electromagnetic physics models used was tested. It was determined that the PGNAA sensor model can reproduce measurements obtained from the GEOSCAN sensor. In particular, the model can provide a good reproduction of the overall spectral shape and the locations of distinct characteristic peaks. The differences between simulated and experimental results are within 30% on average. It was found that the Geant4 HP neutron model best reproduces the activation peaks observed in experimental measurements. Additionally, the PGNAA spectrum was found to be insensitive to the choice of electromagnetic model for the photon interactions. The validated sensor model provides a useful tool for investigating PGNAA sensor applications including a bulk sorting strategy for new materials, sensor calibration, improvements in signal analysis and optimised sensor design.

In ores containing rutile, chlorite is the most common silicate gangue mineral. However, the flotation separation of rutile and chlorite has yet to be thoroughly studied. In this study, carboxymethyl cellulose (CMC) was used to depress chlorite when sodium oleate (NaOL) was used as the collector of rutile. The selective depression and its mechanism were investigated through micro-flotation experiments, zeta potential analyses, Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and particle video microscopy (PVM). Single mineral flotation showed selective depression of chlorite by CMC appeared at pH 7, NaOL concentration of 20 mg/L, and CMC concentration of 10 mg/L, when 88.39 % recovery difference between rutile and chlorite was obtained. The most effective concentration of CMC for the artificially mixed ore test was 15 mg/L, resulting in rutile recoveries and grades of 87.78 % and 75.28 % respectively. The results of Zeta, FTIR, and XPS tests indicate that the adsorption of CMC on chlorite surface is attributed to chemical and hydrogen bonding interactions, wherein the OH– and COOH– groups in CMC interact with hydroxyl groups of Fe²⁺ and Al³⁺ complexes, thereby diminishing chlorite floatability and impeding subsequent NaOL adsorption. PVM image further elucidates that hydration-repulsion interaction potentials between CMC-absorbed chlorite particles and gas bubbles deter particle adhesion. This markedly reduces chlorite ore carryover on bubble surfaces while minimally impacting rutile. This study can provide a theoretical basis for separating rutile and other vein minerals under the NaOL system.

The influence of mechanical activation (MA) and mechanochemical activation (MCA) with Fe and Fe₂O₃ on the microstructural changes, leachability and leaching rate of natural chalcopyrite was investigated and compared. MCA pretreatments were carried out by chalcopyrite co-milling with Fe and Fe₂O₃ for 20 and 50 min. The XRD analysis indicated that even after 50 min MA and MCA, constituent phases of chalcopyrite, Fe and Fe₂O₃ could be detectable beside the newly formed bornite. Regarding the peak broadening and peak intensity reduction, MCA generally intensified the microstructural changes of chalcopyrite in comparison with MA. The microstructural study performed by the Rietveld method also proved that all microstructural parameters changed in favor of reactivity, such that the amorphization degree and microstrain were increased to 96 % and 0.164 (%), respectively, while crystallite size was reduced to 14.6 nm after 50 min MCA of chalcopyrite with Fe₂O₃. It could be concluded from the leaching tests that MCA along with Fe and Fe₂O₃ addition could promote the leachability and leaching rate of chalcopyrite, as compared to MA and nonactivated chalcopyrite. Although both the MCA of chalcopyrite with Fe and Fe₂O₃ could enhance copper extractions in the 1 M sulfuric acid leaching tests at 80 °C, Fe addition was slightly more effective than Fe₂O₃. The results obtained from the kinetic study also revealed that the leaching mechanism of nonactivated chalcopyrite, mechanically activated chalcopyrite and mechanochemically activated chalcopyrite with Fe₂O₃ changed from diffusion control to chemical control due to MCA with Fe. Finally, the combination of kinetic and microstructural studies proved that all microstructural parameters, except for the microstrain parameters of chalcopyrite MCA with Fe₂O_3, could be effective in chalcopyrite reactivity promotion.

Copper (Cu) extraction from low-grade ores is limited by the formation of secondary minerals that can passivate the surfaces of Cu-sulphide minerals in these ores. Hence, a novel approach utilizing AlCl₃ as a lixiviant was developed to modify coupled dissolution-reprecipitation processes at the mineral interface. The formation of Al-rich phases instead of Fe-hydroxysulphates enhanced Cu extraction through combined ferric-iron and proton-promoted dissolution. AlCl₃ accelerated chalcopyrite and bornite dissolution by forming soluble intermediate Cu-phases (e.g., covellite) at consistently high Eh (550–650 mV) and acidity due to the Lewis acid property of AlCl₃. X-ray diffraction analysis revealed that Na-bearing jarosite [(K_0.61Na_0.41) Fe₃(SO₄)₂(OH)] and sideronatrite [Na₂Fe(SO₄)₂(OH)(H₂O)] formation in lixiviants without AlCl₃ decreased Fe³⁺_(aq) availability for Cu-sulphide minerals dissolution. In contrast, significant amounts of AlSO₄⁺_(aq) formed in the AlCl₃-rich lixiviant at pH 1–3, which reduced the sulphate activity and decreased the saturation state of the Fe-hydroxysulphates. Further, AlCl₃ promoted the formation of amorphous, porous Al-rich phases, facilitating quick Fe diffusion through the passivating layer and improving Cu recovery compared to lixiviants containing CaCl₂, NaCl, or acid-only.

Tracking mill liner wear is essential for improved plant reliability and grinding performance. This study developed a novel IoT wear sensor and a Discrete Element Modelling coupled methodology to predict and continuously evolve shell liner’s wear pattern. The IoT sensor was purposely developed to track and report the live thickness of a shell liner. Global wear pattern was then obtained by coupling the qualitative wear intensity obtained in DEM and sensor results, from which a topological evolution model was established to generate the shell liner’s progressive wear profiles. Predictions of the wear evolution model were compared with 3D laser scan measurements collected during operation. Results indicated that the wear evolution model showed less than 8% error with laser scan measurements in quantitative wear rate comparison.

The beneficiation and recovery of ores with complex nature, low abundance have become the main direction for the development of niobium resources. The niobium resources with large reserves in Bayan Obo have not been effectively developed due to their fine particles, low grade, and complex nature. A new method for the phase reconstruction of minerals through a reconstruction process was proposed. The reconstruction of Bayan Obo niobium-bearing rougher concentrate was realized by a high-temperature melting-cooling crystallization process. The impacts of multielement basicity on the reconstruction of niobium-bearing minerals were investigated by adjusting the composition of the slag in this study. The loparite ((Ca,Ce,Na)(Nb,Ti)O₃) phase is formed in slag with a higher basicity. On the contrary, the calciobetafite (Ca₂(Nb,Ti)₂O₇) is generated in slag with a lower basicity. Besides, the combined mass fractions of valuable TiO₂, Nb₂O₅, and rare earth oxide (REO) in calciobetafite reaches 71.94% (only 56.83% in loparite). The formation mechanism of niobium-bearing phases under different basicities was also discussed. The results of this study can provide theoretical guidance for transforming the niobium-bearing phase and enriching valuable elements in the process of phase reconstruction.

“Peak carbon dioxide emissions、Carbon neutrality” is the two stage goal of carbon emission reduction proposed by China. Carbon emission accounting is the basic premise for effectively carrying out various carbon emission reduction work and promoting the green transformation of the economy. The coal industry is one of the key objects of carbon emission reduction. Taking Zhenneng Coal Preparation Plant as the research object, this paper studies the carbon emission in the production process of the coal preparation plant and the selection of carbon emission factors, and constructs the carbon emission accounting model of the coal preparation plant. It is calculated that the carbon dioxide equivalent emission per 1 t of coal products produced by the coal preparation plant in 2018–2022 is 15.4391 kgCO₂e. Based on the carbon emission reduction path at home and abroad, the development suggestions for carbon emission reduction in coal preparation plants are put forward. It is of great significance to establish a unified and standardized carbon emission accounting system for the coal industry, achieve the goal of “double carbon” and promote the comprehensive green and low-carbon transformation of economic and social development.

Concentration of spodumene from lithium pegmatite ore generates large amounts of tailings that need to be recycled for sustainability and circular economy concerns. This study investigated the preparation of high-alumina porcelain compositions incorporating spodumene tailings, i.e., quartz feldspar silt (QFS). The mix design closely matched the theoretical composition of 60.51-wt.% Al₂O₃, 34.34-wt.% SiO₂, 2.98-wt.% K₂O, 0.66-wt.% Na₂O, and 0.33-wt.% CaO. For comparison, a reference composition free of QFS, composed of commercial materials, was also prepared. Both compositions were thermally treated at 1200℃, 1300℃, and 1400℃. The prepared samples were characterised using several techniques, including X-ray diffraction, scanning electron microscopy–energy-dispersive X-ray spectroscopy, thermogravimetry/differential scanning calorimetry, compressive and flexural strength tests, water absorption, apparent density, and dilatometry at high temperatures up to 1400℃. The results show that corundum and mullite are the primary crystalline phases formed at high temperatures in addition to an amorphous glassy phase. The compressive and flexural strengths were 25–60 and 6–10 MPa, respectively. QFS milling favoured phase densification, resulting in greater sintering shrinkage. However, all samples were relatively stabilised after the first heating cycle and exhibited less than 1% dimensional changes during the second heating cycle at 1400℃. The reference and 26.4-wt.% QFS samples exhibited comparable results, indicating the potential for upcycling spodumene tailings as feldspar substitutes in the development of corundum-mullite based-ceramics for possible high temperature applications.