A discussion on collaborative development of low-altitude economy (LAE) and mining & metallurgical engineering (MME), as well as the two-way empowerment mechanism is presented. Low-altitude technologies, such as unmanned aerial vehicle (UAV) and electric vertical take-off and landing aircraft (eVTOL), can be used to reshape MME, while MME can provide core materials for low-altitude aircraft. However, the collaboration between them is limited by disciplinary barriers and talent gaps, so it is necessary to build a dual system of “technology chain－talent chain”. This can be achieved by adding interdisciplinary courses, establishing actual flight certification bases in mining areas, promoting integration of relevant qualification certifications, and accelerating incubation of key technologies based on low-altitude economic industrial parks. These measures can break down discipline barriers, shorten the cycle of technology transformation, and provide support for the in-depth integration and collaborative development of LAE and MME.

With the red mud from Guizhou as raw material, an experiment was carried out by adopting a process of low-temperature acidification roasting followed by water leaching to recover scandium, and effects of factors, including sulfuric acid dosage, temperature and time for roasting process, liquid-solid ratio of leaching solution, leaching temperature and time, on scandium leaching rate were investigated. It is shown that after 4 h-roasting at 200 ℃ with sulfuric acid and raw ore in a mass ratio of 1∶1, and then 4 h-leaching at 80 ℃ with leaching solution and solid in a mass ratio of 6∶1, the leaching rate of scandium can be finally up to 89.10%.

In an experiment, oxidative precipitation method was adopted to remove iron from crude nickel sulphate solution. With H₂O₂ or Cl₂ as oxidant, Fe²⁺ in the solution was oxidized to Fe³⁺, and then Fe³⁺ was precipitated in the form of Fe(OH)₃ and FeOOH by adjusting the pH of the solution. It is found that under the optimum conditions for iron removal with H₂O₂ as the oxidant, including H₂O₂ dosage of 3.84%, temperature of 75 ℃, pH of 4.5, dropping of H₂O₂ solution at a rate of 0.33 mL/min, and the aging time of 90 min, the removal rate of iron can reach 99.74%. Under the optimal conditions for iron precipitation with Cl₂ as oxidant, including reaction temperature of 70 ℃, pH of 4.5, Cl₂ injection time of 60 min and aging time of 90 min, the iron removal rate can reach 99.72%. It is shown that the solution after iron removal with H₂O₂ or Cl₂ as an oxidant can have the iron content therein up to the class I standard (iron content no more than 0.000 5%) in GB/T 26524—2023 Refined Nickel Sulfates.

To address problems of accuracy and efficiency in automatically reading of float flowmeter at low flow rates under a complex environment in sintering kilns for new energy materials, an innovative YOLOFFM algorithm was proposed. The core improvements include reconstructing the backbone network, enhancing the neck structure, introducing an asymmetric compression decoupling head, and optimizing the loss function, which can significantly improve the efficiency and detection performance of the algorithm. The results show that this YOLOFFM algorithm has accuracy up to 99.15% and a recall rate of 98.69%, significantly reducing the number of model parameters and computational costs. Compared with various advanced algorithm models, YOLOFFM can improve accuracy while reducing the computational cost by more than 90%, fully demonstrating its high efficiency and reliability for new energy materials in a complex environment of sintering kilns.

To investigate the fracture characteristics of rocks with bent cracks under saturated condition, uniaxial compression tests were conducted for rock specimen with different inclination degrees and numbers of crack bends under saturated conditions to study load-displacement curves, peak strength, acoustic emission characteristics, crack initiation modes, and penetration modes of the rock specimen. The results show that the load-displacement curve of saturated rock specimen with bent cracks presents one-peak or double-peak shape, with peak strength increasing after an initial decreasing as the crack inclination angle becomes larger. The acoustic emission signals become stronger as the crack inclination angle becomes larger and the number of crack bends increases. Cracks mainly initiate at the tip and bends, and mainly penetrate directly or run without penetration.

Single mineral flotation tests of chalcopyrite oxidized respectively in air and water were carried out under optimized conditions such as pulp pH and collector dosage. The mechanism for oxidation bringing effect to the floatability of chalcopyrite was studied by measuring contact angle and Zeta potential, and using infrared spectroscopy. The results show that the recovery of oxidized chalcopyrite with collector JXZZ is higher than those using DJHY and BXZX; the surface hydrophobicity of chalcopyrite oxidized in air and water can be improved; the area of CO₂ absorption peak increases with the increase of air oxidation time, air oxidation temperature and water oxidation time, and all the three collectors can be chemisorbed on chalcopyrite. After oxidation, point of zero charge of oxidized chalcopyrite shifts positively, while the oxidization state of chalcopyrite in water is comparatively stable. It can be concluded that the floatability of chalcopyrite can be regulated by surface oxidation of this ore.

The ore in the concentrator of Anhui Taiping Mining Company cannot reach the expected flotation effect. In order to address the problem, the properties and particle size composition of raw ore were analyzed, and condition tests were conducted to rule out the influence of reagent system and flotation conditions on the flotation performance. Based on a test on pre-desliming of the raw ore sample before grinding and the concentrate from pretreatment, it is found that the secondary slime has a significantly superior floatability than the primary slime, and too much primary slime is a contributing factor in the finally poor flotation performance. And based on a test on comparison of desliming, it is found that after pre-desliming process, the flotation effect of ore can be obviously improved, and the concentrate can have its final recovery improved by around 10 percentage points compared to that without pre-desliming process, due to significantly decreased slime content in concentrate and middlings. It is concluded that pre-desliming process is an effective approach for improving flotation performance of such kind of copper-bearing ore with serious sliming.

Effect of annealing temperature on the mechanical properties and fatigue properties of Al-Cu-Mg-Ag alloy was explored by preforming fatigue crack propagation (FCP) rate testing, room-temperature tensile test and using characterization means such as X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the T4 state specimen annealed at 420 ℃ for 4 h presents higher yield and tensile strength, but poor plasticity. As the annealing temperature increases within the range of 400－430 ℃, the orientation density of the Goss texture in the alloy first increases and then decreases, and the T4 specimen after 4 h annealing at 420 ℃ presents an optimal fatigue performance, with lower FCP rate around 1.34×10^－3 mm per cycle at ΔK≈20 MPa·m^0.5.

In order to solve the problems of fuzziness, randomness and uncertainty in optimization of mining method by traditional analytic hierarchy process (AHP), some measures, including introducing fuzzy theory, optimizing judgment scale and constructing optimal transfer matrix, were introduced to reduce subjective deviation and enhance the processing ability of uncertain information. Then, based on the combination of improved analytic hierarchy process (AHP) with the technique for order preference by similarity to ideal solution (TOPSIS), a comprehensive evaluation system with multi-level, multi-factor, multi-objective and multi-index characteristics was constructed and applied to the optimization of mining methods for a gently-inclined medium-thick phosphate ore body. The analysis shows that the relative closeness coefficients of those three mining schemes are 0.177 9, 0.822 5 and 0.648 3, respectively. Scheme 2, namely sublevel open stoping with subsequent backfill, is primarily determined as the suitable mining method for the mine. The numerical simulation of Scheme 2 also shows that the maximum surface subsidence in this scheme can be controlled within 72.94 mm, indicating that the mining operation at this stage brings little impact to the surface industrial zone on the mining site.

The process of extraction and separation of indium and Fe(III) requires a step of reduction of trivalent iron in advance and also emulsification is prone to occur. In order to solve the problems, an experimental study was carried out with acid leaching solution of volatile dust from a domestic large-scale zinc smelting enterprise to explore the processing technique of direct extraction with a extractant system of DY23 (a combination of extractant A and co-extractant M) to recover indium without a step of reduction of Fe(III) in advance. Based on the experiment, effects of organic phase concentration, phase ratio in extraction, extraction time and temperature on the separation between indium and Fe(III) were investigated. It is found that with a combined extraction system, consisting of 30% extractant A, 10% co-extractant M and 60% sulfonated kerosene, O/A ratio of 1∶1, the leaching solution of volatile dust is subjected to a two-stage countercurrent extraction at room temperature for 1.5 min, leading to indium extraction rate exceeding 99% and extraction rate of Fe(III) at only around 10%, presenting a good separation effect. The loaded organic phase is then subjected to a stripping process with 4 mol/L hydrochloric acid after being washed with 200 g/L sulfuric acid, leading to the stripping rate of indium exceeding 95%. After stripping of indium, the organic phase is subjected to another stripping with 70 g/L oxalic acid to remove Fe(III), resulting in the stripping rate of Fe(III) up to 98%. It is concluded that indium and Fe(III) therein can be effectively separated.