To address the problems of poor fluidity and high viscosiy, ore rocks and higher ore losses and dilution due to the influence of moisture content on eastern stopes of Jinshandian Iron Mine, the variation laws of fluidity of ore blocks, shape characteristics of drawn ore blocks, as well as loss and dilution indices of two types of ore bodies in the eastern stopes under influence of different moisture content were analyzed by preforming physical tests and numerical simulation. A reasonable range of drift spacing for the eastern stopes was determined, which was then optimized from the perspectives of safety, technology and economy, based on the improved CRITIC-TOPSIS evaluation method. The results show that with the moisture content in a range of 0－8%, the drawn ore blocks in the eastern stopes are in a shape of an “inverted water drop”, and become shallow as the moisture content increases; with the moisture content in a range of 4%－8%, the natural angle of repose of ore rocks increases with the increase of moisture content, the recovery rates of those two ore bodies are negatively correlated with moisture content, and present an upward trend followed by a decline as the drift spacing becomes wider, while the dilution rate follows the opposite trend. With the moisture content at 6% on average, the optimal drift spacing in the eastern stopes of Jinshandian Iron Mine should be set at 15 m.

The parameters of the Fuzzy Measure Method (FMM) in slope stability analysis are difficult to determine, thus a support vector regression (SVR) model was established and used to accurately predict parameters of the FMM, and a slope stability prediction model, FMM-SVR, was established, which was then used to predict the instability probability of the slope during the second-phase open-pit mining in Gaocun Iron Mine of Masteel Mining Resources Corporation. The results show that the maximum slope instability probability is 0.120 8 as mining operation approaches the toe of slope in an open pit, indicating that the slope remains overall stable with a risk of partially instability. This conclusion is also consistent with the on-site measured results. The location of the most critical sliding surface of the slope was determined by the finite element strength reduction method, and the factor of safety is calculated to be 1.5, which further verifies the effectiveness of the FMM-SVR model.

To improve the accuracy of fracture recognition in borehole images, a borehole fracture recognition approach for open-pit mine was proposed. First, borehole images of an open-pit mine is obtained with an intelligent borehole inspection camera, and then data augmentation is performed by using random cropping and image flipping, while median filtering is used for noise reduction and images are converted to grayscalere, so as to eliminate noise and reduce computational complexity. Next, spatial attention and channel attention mechanisms are integrated into the U-Net model to improve the semantic segmentation model for fractures, forming an AU-Net model, which can enhance the model′s ability to extract features from both overall and local image information. Experimental results show that compared to the original U-Net model, the AU-Net model can achieve lower loss and higher accuracy in the fracture recognition dataset by borehole imaging. Specifically, the mean intersection over union is improved by 4.38 percentage points, up to 82.34%, bringing better image segmentation effect.

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.

A copper-gold ore from Xizang grades 0.50% Cu and 0.24 g/t Au, in which chalcopyrite as the dominant copper mineral is finely disseminated. It was proposed that a stepwise flotation process be employed to process this ore. At the first-stage roughing, a non-polar collector CM-2 was adopted under low-alkaline conditions to recover those easily floatable copper and gold minerals, and at the second-stage roughing, Z-200 was adopted to enhance copper flotation effect, so as to improve the recovery rates of copper and gold. A closed-circuit experiment yielded a copper-gold concentrate grading 22.33% Cu and 9.96 g/t Au at the corresponding recoveries of 90.57% and 79.83%, respectively. Compared to high-alkaline flotation processes with ethyl xanthate or Z-200 as collectors, this stepwise flotation process can increase gold recovery by more than 10 percentage points. This technical process can not only avoid depression effect of lime on gold minerals, but also strengthen the collecting effect of copper and gold minerals, thus achieving efficient resource recovery. This study can provide a reference for exploitation and utilization of similar ores.

A beneficiation experiment for super enrichment was carried out with the low-grade niobium ore from western zone of Bayan Obo mine. In the experiment, a process of magnetic separation followed by gravity concentration for tailings discarding was firstly adopted for pre-concentration, and the obtained rougher concentrate grading 2.61% Nb₂O₅ was subjected to a reverse flotation for desulfuration, followed by a direct flotation with CYN-7 as a collector and CYD-2 as a depressant for recovering Nb minerals, resulting in efficient separation between Nb and other gangue minerals. It is found that the raw ore grading 0.06% Nb₂O₅, with a grinding fineness of－0.074 mm 85% is treated by magnetic separation and gravity concentration for tailings discarding, followed by a reverse flotation for desulfuration, and a direct flotation consisting of one stage of roughing and three stage of cleaning. As a result, a Nb concentrate grading 22.37% Nb₂O₅ at 33.64% recovery can be finally obtained.

In order to comprehensively recover titanium resources and iron resources from a low-grade ilmenite ore, an experimental study was performed for the ore by a process of low intensity magnetic separation (LIMS) followed by regrinding and re-concentration to recover Ti and Fe therein. The results show that LIMS with ore at a grinding fineness of－0.074 mm 84.78% can yield an iron concentrate grading 62.82% TFe and 3.62% TiO₂ with iron recovery of 51.32%, presenting a good recovery of magnetic iron; the obtained LIMS concentrate is subjected to high-intensity magnetic separation (HIMS) consisting of one roughing and one cleaning, followed by gravity separation with a shaking table, resulting in the obtained Ti concentrate grading 40.81% TiO₂ at 18.47% recovery. It is shown that both Fe and Ti therein can be comprehensively recovered.

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.

Under the current production conditions, the fluorite concentrate obtained from the associated fluorite resources in a mine of Hunan Province has its processing indicators undesirable and fluctuating widely. In view of this technical bottleneck, a new processing technique was developed to recover such kind of fluorite ore for improving the quality of resources. In this technique, a principle of alkaline environment followed by acidic environment was adopted in the cleaning stage, and also the middlings obtained from the cleaning stage are returned to be processed again. As a result, a full-process closed-circuit test yielded 13.67% high-grade fluorite concentrate grading 96.11% CaF₂ at 60.13% recovery, and 3.93% low-grade fluorite concentrate grading 85.08% CaF₂ at 15.34% recovery. The comprehensive concentrate has a CaF₂ grade up to 93.65%, with total recovery of 75.47%. It is concluded that this low-grade associated fluorite ore can be efficiently and comprehensively recovered using this technique.