In view of low prediction accuracy and slow speed of traditional prediction methods for strip crown, a weighted prediction model based on random forest (RF) and support vector machine (SVM) was established. The parameters of models based on RF, SVM, and a combination of RF and SVM were optimized respectively by adopting the improved coati optimization algorithm (ICOA), so as to improve crown prediction accuracy. A 1 580 mm production line of a hot-rolling mill in one company was taken in a simulation research on crown prediction based on its actual measurement. The root mean square error of the weighted prediction model based on RF and SVM is 2.23 μm. It is found that this weighted prediction model has its prediction accuracy increased by 7.08% and 2.62% respectively, compared with the models based on RF and SVM respectively.

A seabed collector vehicle usually carries a large amount of sediments during mining seabed polymetallic nodules. For reducing the environmental impact caused by tail water discharged in the mining, two kinds of high efficiency and low diffusion desliming pretreatment devices, with twine-drum spiral structure and a direct discharge device with arresting mesh structure, respectively, have been developed, which integrates a jet-assisted transport testing equipment, and is also equipped with an online monitoring system. The desliming effect and environmental performance of the developed device was evaluated by performing computational fluid dynamics simulations and laboratory tests. It is found that the direct discharge device with arresting mesh can pretreat tails with desliming rate over 98%, and this pretreatment device can make quick separation of nodules from sediment, and also lead to subsequent quick settlement of the separated sediment, thus effectively controlling the plume caused by collector in the mining. It is concluded that this developed pretreatment device can improve the lifting efficiency in the mining and mitigate the pollution of tails in the deep-sea mining from the source.

A kind of polymetallic lead-zinc sulfide ore in Guangxi was taken for experimental research. In view of its characteristics of high zinc and low lead, as well as difficulty in the separation between zinc and lead, a new type of efficient inhibitor JFR-1 was adopted in the experiment. It is shown that the lead-zinc sulfide ore was subjected to a lead-zinc bulk flotation, consisting of one roughing, two cleaning and two scavenging, followed by a separation of lead and zinc, consisting of one roughing, two cleaning and two scavenging, finally resulting in a lead concentrate grading 21.00% pb at 72.82% recovery, a zinc sulfide ore grading 6.96% Zn at 94.21% recovery, and a tailings grading 0.04% Pb and 0.13% Zn with a lead recovery of 10.85% and a zinc recovery of 4.79%. Thus, the enrichment and separation of lead and zinc can be actualized.

Illite, a kind of clay mineral, was taken as an adsorbent in an experiment for low-concentration rare earth ions in rare earth leaching solution to explore effects of initial concentration of Y³⁺, adsorption temperature, pH value of solution, ion concentration, and adsorption time on the adsorption behavior of illite. Then, based on the constructed isotherm model for adsorption of yttrium ions by illite and its reaction kinetic model, the mechanism for the adsorption of yttrium ion by illite was analyzed. Results show that illite has an excellent adsorption performance for Y³⁺. With an increased initial concentration, higher temperature, prolonged time, and higher pH value of solution, the adsorption capacity of Y³⁺ for illite increases. It is found that the existence of Na⁺, Mg²⁺ and Al³⁺ can inhibit the adsorption of Y³⁺ by illite in the following descending order of importance: Al³⁺>Mg²⁺>Na⁺. The adsorption reaction follows Langnuir isotherm model and pseudo-second-order reaction kinetic model. Ion exchange reaction takes place during the adsorption process, thus this adsorption process belongs to chemical adsorption, with adsorption rate controlled by chemical reaction.

A composite photocatalyst of TiO₂-CNTs was synthesized by adopting the sol-gel method and ultrasonic dispersion, and then its activity in the photocatalytic reduction of CO₂ was tested. With a load capacity of carbon nanotubes (CNTs) at 0.75%, the TiO₂-CNTs present a better performance in photocatalytic CO₂ reduction. Under UV irradiation with wavelength of 365 nm, the average yield of CH₄ and CO from the composite catalyst are enhanced by 90% and 156% respectively, compared to the usage of single TiO₂ catalyst. It is believed that the reaction is based on the following mechanisms: CNTs, as a co-catalyst, forms a compact electron transport structure with semiconductor of TiO₂, which significantly accelerates the transfer of photogenic carriers and reduces the electron-cave recombination efficiency. In addition, high specific surface area and excellent adsorption performance of CNTs can increase active sites for reaction, thus improving efficiency of photocatalytic reduction of CO₂ by the catalyst.

For estimating the amount of infiltrated water during heavy rainfall after transition from open-pit mining to underground block caving, the Beiyi mining area of Shilu Iron Mine in Hainan Province after transition from open-pit to underground mining was taken for study. The characteristics of “three zones” formed due to overburden subsidence during the block caving of Beiyi mining area were analyzed based on the field investigation and numerical simulation of land subsidence area. The influence of different overburden on the infiltration coefficient of rainfall was also analyzed with a numerical calculation model for unsaturated overburden. Then, based on the practical measurement of rainfall and drainage, statistical analysis and inverse analysis were conducted for the infiltration coefficient of the caving zone and the surface runoff coefficient. The infiltrated water due to heavy rainfall in Beiyi mining area after transition from open pit from underground mining is calculated to be 225 386 m³, which can provide a reference for the design of infiltration and drainage system for the mine after transition from open-pit to underground mining.

To study the distribution of flow and pressure in the slurry pipeline of large-diameter slurry shield, Simcenter Flomaster was used to simulate the slurry pipe for calculation, and a one-dimensional model was established for the slurry pipe of large-diameter slurry shield. The distribution of flow and pressure in the pipeline under different working conditions by changing the valve opening degree, fluid density and rotating rate of pump were recorded, so as to obtain the optimal flow distribution. The calculation results show that valve opening degree, fluid density and rotating rate of pump all have a certain influence on the distribution of flow and pressure in the slurry pipeline system. By increasing valve opening degree, the flow rate in the pipeline increases and the pressure difference between two ends of the pump is reduced; as the fluid is changed from clear water to slurry, the flow rate in the pipeline increases and the pressure difference between two ends of the pump decreases; as the pump rotates at a lower rate, both the flow rate and the pressure difference are reduced. If the rotating rate of discharging pump is too low, the discharging pipe can be kept operating normally by increasing the rotating rate of the discharging pump or adding another pump in series.

Based on the investigation of occurrence state, fluoride associated with barite was leached with HCl-AlCl₃ by using Plackett-Burman design, and influences of HCl concentration, AlCl₃ concentration, reaction temperature, reaction time, and liquid-to-solid ratio on fluorine leaching rate were investigated. It is found that the fluorine in barite mainly exists in the form of disseminated and banded fluorite. By using HCl at a concentration of 3 mol/L and AlCl₃ at a concentration of 0.4 mol/L, after 30 min leaching reaction of ore sample with grain size of 48-75 μm, liquid-to-solid ratio of 10 mL/g, and stirring speed at 300 r/min, the leaching rate of fluorine can reach 93.20%, and the mass fraction of barite is 95.91%. Results show that all factors that influence fluorine leaching rate are arranged in descending order of importance as follows: reaction temperature > HCl concentration > reaction time > AlCl₃ concentration > liquidto-solid ratio.

Aiming at problems including low content of magnetic iron, fine dissemination size and high content of ferrous silicate in processing of the amphibole-type primary ore in Yuanjiacun Iron Mine, an experimental study was carried out by adopting a pre-concentration process consisting of fine crushing plus dry magnetic pulley separation and a roll grinding plus wet magnetic separation. The pre-enriched concentrate was then processed with a flowsheet including a three-stage grinding, a three-stage low-intensity magnetic separation and a reverse flotation, resulting in an iron concentrate grading 65.66% TFe at 49.31% recovery, with the yield of 21.45%. It is shown that iron resource can be utilized efficiently.

The effects of sulfuric acid concentration, calcite particle size, sodium dodecyl sulfate (SDS) dosage and flow rate of dynamic fluid on the apparent density of calcite particles during acid reaction were studied. The results show that when the sulfuric acid concentration is 1%, calcite can sustain at the low apparent density state, and the smaller the calcite sizes, the lower the apparent densities. SDS with a concentration of 300 mg/L can enhance the hydrophobicity of calcite, increase effectively the adsorption density and residence time of CO₂ bubbles on calcite, and prolong the duration of low apparent density of calcite. Dynamic fluids may accelerate desorption of gas bubbles from calcite, which is detrimental to the reduction of apparent density of calcite during acid reaction process, but the SDS treatment can significantly reduce this detrimental effect. Settling tests show that acid reaction can prolong the settling time of calcite particles, creating favorable conditions for the separation of calcite and non-carbonate minerals by gravity concentration.