The dust generated during chlorination process in recovering titanium by metallurgical process was washed with water. Then, the residue left after water-washing was subjected to calcification roasting process, and the effects of roasting temperature and roasting time on the leaching rate of vanadium from the residue were studied. The results indicate that vanadium in the dust from chlorination process mainly exists as low-valent vanadium, and the vanadium leaching rate increases with the rising temperature. The vanadium leaching rate reaches 88% with the roasting temperature of 850 ℃. As the roasting time increases, the previously obtained different products undergo a secondary reaction, forming insoluble compounds of vanadium bronze, and also vanadate with different valences, which results in different vanadium leaching rates in Na₂CO₃ solution. It is concluded that the roasting process should be optimally at temperature of 850 ℃ with a roasting time of 120 minutes.

An experiment of acid leaching was performed for the concentrate obtained by flotation pretreatment of a refractory sulphide ore. After leaching at 95 ℃ for 2 h, with nitric acid concentration at 9 mol/L, and liquid-solid ratio of 4∶1, the leaching rates of copper and zinc reach 90.46% and 85.34%, respectively, showing no lead leached out. The leaching process is mainly controlled by both solid film and chemical reaction.

The single application of analytical hierarchy process (AHP) and grey relational analysis (GRA) algorithm is always affected by some subjective factors, leading to great deviation between the obtained evaluation result and the actual result. In view of this problem, a composite algorithm based on an integrated range analysis with GRA and AHP was proposed. Then, a phosphate mine in the southwest China was taken as an example, and this algorithm was adopted to analyze the sensitivity of factors, including gravity, internal friction angle, cohesive force, elastic modulus and Poisson's ratio, to the stability of slope in the Area A. The results show that the sensitivity of those influencing factors to the slope stability in Area A is in the following descending order: internal friction angle, cohesive force, gravity, elastic modulus, Poisson's ratio. It is found that the analysis result is consistent with the actual situation of the mine.

The tailings of an iron mine in Baotou, Inner Mongolia, contain fluorite resources with large reserve and low CaF₂ grade. Unfortunately, the gangue minerals in the tailings, such as ankerite, calcite and barite, share similar floatability with fluorite, resulting in difficulty in fluorite recovery. With DKCS, FX-1 and starch introduced to depress ankerite, calcite and barite respectively, fluorite can be effectively separated from gangue minerals with modified oleate acid FH as the collector. It is shown that a closed-circuit test can result in a fluorite concentrate grading 90.68% CaF₂ at 64.69% recovery, showing a comprehensive recovery of fluorite resources from the tailings.

Flotation tests were carried out for a fluorite-calcite symbiosis ore containing 31.09% CaF₂ and 53.23% CaCO₃, with the predominately valuable mineral of fluorite, and the dominantly gangue minerals of calcite, quartz and feldspar. After being milled to a fineness of -0.074 mm 75%, the ore was processed with acidized sodium silicate and EM-318 as depressants and EM-OL-3 as collector. Adopting a close-circuit flowsheet consisting of two stages of roughing, one stage of scavenging and eight stages of cleaning, a fluorite concentrate grading 97.26% CaF₂ at 86.55% recovery can be obtained. Qualified as an acid-grade fluorite powder (with grade FC-97A) according to the Industry Standard for Ferrous Metallurgy (YB/T 5217—2005 (Fluorspar)), this fluorite concentrate can be used as the raw material in high-end fluorine chemical industry.

A process mineralogy study and mineral processing tests were conducted for a copper slag with Cu grade of 0.81%, and a beneficiation flowsheet for recovering copper resource and its technical parameters were determined. With Z-200 and 2^# oil respectively as collector and frother, the slag was processed after being milled to a fineness of -0.038 mm 85%, and a high-grade copper concentrate with Cu grade of 26.40% was collected by fast preferential floatation, while a low-grade copper concentrate with Cu grade of 3.58% was obtained from a subsequent flotation process consisting of one stage of roughing, two stages of scavenging and two stages of cleaning, resulting in the total copper concentrate grading 13.03% Cu at 76.47% recovery. This copper-recovering technique has been successfully applied in commercial practice, showing that the comprehensive utilization of Cu metal resource in a copper slag can be actualized.

The kinetics and thermodynamics of oleate ion adsorption on the surface of fluorapatite and dolomite were studied by adopting TOC measurement and molecular simulation. The study on kinetics of adsorption shows that with HEDP as the depressant, the adsorption rate of oleate ions on fluorapatite is greater than on dolomite, and the adsorption on both minerals conforms to the quasi-second-order kinetic model. Furthermore, according to the study on adsorption thermodynamics, the characteristics of oleate ion adsorption on the inner pore surface of both fluorapatite and dolomite, on (001) surface of fluorapatite and (104) surface of dolomite nearly conform to Langmuir model. For identical specific surface area, the adsorption amount of oleate ions on dolomite is higher than that on fluorapatite, indicating that there are more active sites per unit surface area on dolomite than on fluorapatite.

With orange residue extract and tetrasodium glutamate diacetate (GLDA) as raw materials, a green activator was prepared. Then, the effects of phosphate-solubilizing bacteria (PSB) combined with green activator on the enrichment, translocation and accumulation of cadmium from soil by ryegrass were studied. The results show that PSB can significantly promote the growth of ryegrass in cadmium-contaminated soil. However, the growth of ryegrass is inhibited by only using green activator, with the dry weight of ryegrass at the end of experiment decreased by 27.37%; while a combination of PSB and green activator can make the final dry weight of ryegrass become 1.29 times that in the blank group, indicating that the addition of PSB can alleviate the negative effect of green activator on the growth of ryegrass. A combination of both can increase the content of phytoavailable cadmium in soil, while decrease the total cadmium concentration in soil. It is shown that the enrichment coefficient of Cd in stem and root parts of ryegrass increases by 35.37% and 10.23%, respectively, and the translocation factor of cadmium by ryegrass increases by 22.58%. In addition, the total accumulation of cadmium in the stem and root parts of ryegrass is up by 87.90% and 32.69%, respectively. It is found that the total accumulation of cadmium in the stem is all greater than that in the root whether by using PSB and green activator separately, or by a combination of both, indicating that PSB combined with green activator can promote the phytoextraction efficiency of cadmium from soil by ryegrass.

Aiming at problems of high mud content in tin tailings from Russia, finely disseminated particle size of cassiterite, and influence of sulfur and iron content on tin recovery rate, a combined process consisting of sulfide ore flotation, cassiterite preconcentration, and cassiterite flotation was adopted in a beneficiation test. It is found that the dominant tin mineral in tailings is cassiterite, and sulfide minerals therein include pyrite, pyrrhotite among others, while the dominant gangue includes quartz and tourmaline. The effect of sulfide ore and iron ore on subsequent cassiterite flotation can be reduced by adopting cassiterite preconcentration process for waste discarding. With the cassiterite grading 0.31% Sn, the beneficiation test with a combined process consisting of sulfide ore flotation, cassiterite preconcentration and cassiterite flotation can produce a concentrate grading 5.60% Sn at 34.01% recovery.

Flotation technique was introduced to reclaim copper resource from a copper smelting slag with Cu grade of 2.70%. With sodium sulfide as the regulator, the scavenger middling was collected for flotation and its tailings were classified into a size range of +20 μm to return, together with the cleaning concentrate of middling, to the quick flotation stage. With this optimized flowsheet, a stage of scavenging can be dislodged and the mud content in the middling can be reduced. Finally, a closed-circuit test produced a copper concentrate grading 20.59% Cu at 91.75% recovery, and the tailings with Cu grade reduced to 0.26%.