组合捕收剂硫化浮选氧化铜的机理和应用（英文）

通过浮选试验、芘荧光探针、zeta电位和红外光谱分析,研究组合捕收剂丁钠黄药(NaB X)和十二胺(DDA)对氧化铜浮选的影响。单矿物浮选试验表明,在pH7～11条件下,NaBX+DDA的浮选效果优于NaBX,其中NaBX与DDA的最佳摩尔比为2:1。实际矿的浮选试验表明,NaBX和DDA的用量为(100+54) g/t时,精矿中铜的品位和回收率分别为15.93%和76.73%。芘荧光探针结果表明,NaBX+DDA可降低胶束在矿浆中形成的浓度。Zeta电位和红外光谱测试结果表明,NaBX+DDA通过化学吸附、氢键吸附和静电吸附作用在孔雀石表面,并生成黄原酸铜和铜胺络合物。

Effect of sodium alginate on reverse flotation of hematite and its mechanism

Given the gradual increase in the chlorite content of hematite ores, pulp properties seriously deteriorate during flotation. The traditional anion reverse flotation of hematite cannot effectively eliminate the effects of chlorite, leading to a significant decrease in the total Fe(TFe) grade of the concentrate. In this work, the effect of sodium alginate on the reverse flotation of hematite was systematically investigated. Flotation tests of artificially mixed ores were conducted, and the results showed that sodium alginate can significantly improve the removal rates of quartz and chlorite. The adsorption measurements, infrared spectroscopy, and contact angle tests demonstrated that sodium alginate adsorbs on the quartz surface by chelating with calcium ions, thereby weakening the steric hindrance of oleate ions and increasing the adsorption capacity of sodium oleate to ultimately improve the removal rate of quartz. Furthermore, owing to its lower density and fine particle size, chlorite is easily entrained into the foam layer. Sodium alginate dramatically increases the liquid-to-gas ratio of the foam layer by increasing pulp viscosity, thereby increasing the entrainment rate of chlorite and finally improving its removal rate. The core content of this thesis bears significance in improving the Fe grade in the reverse flotation of chlorite-containing hematite.

Interactive effect of minerals on complex ore flotation: A brief review

Froth flotation is the most effective industrial method used to separate fine-grained minerals. The main problem of complex ore flotation is the negative effect of interactions among minerals in slurry, leading to variation in surface properties during separation. In this review,studies on the interactive effect among minerals on the flotation of iron ores, magnesite ores, and scheelite ores are summarized, and the main problems and mechanisms that diminish the separation efficiency of minerals are revealed in detail. Recent research progress on the flotation of these ores has confirmed that mineral aggregation, coating, and dissolution, as well as other factors caused by interacting behavior, explain the depressing effects of fine particles on mineral separation. Solvable methods for these effects are further discussed. Novel flotation processes and more selective reagents are critical for further investigations on various approaches to improve the beneficiation efficiency of these ores.This review aims to provide a good reference for conducting studies related to complex ore flotation.

Selective flotation separation of andalusite and quartz and its mechanism

The separation of andalusite and quartz was investigated in the sodium oleate flotation system, and its mechanism was studied by solution chemical calculation, zeta-potential tests, Fourier transform infrared spectroscopic(FTIR), and X-ray photoelectron spectroscopic(XPS). The flotation tests results show that FeCl3·6H2O has a strong activation effect on andalusite and quartz and citric acid has a strong inhibitory effect on activated quartz, thus increasing the floatability difference between quartz and andalusite when the pulp p H is approximately 8. The FTIR, Zeta potential, and XPS analyses combined with the chemical calculation of flotation reagent solutions demonstrate that Fe forms hydroxide precipitates on the surface of andalusite and quartz and that oleate anions and metal ions adsorb onto the surface of the minerals. The elements Al and Fe can be chemically reacted. The anions in citric acid have different degrees of dissolution of Fe on the andalusite and quartz surfaces, thereby selectively eliminating the activation of the elemental Fe on andalusite and quartz and increasing the floatability of andalusite, leading to a better separation effect between andalusite and quartz.

Improving the sulfidation-flotation of fine cuprite by hydrophobic flocculation pretreatment

Hydrophobic flocculation pretreatment was performed to assess its effect on the recovery of fine cuprite in sulfidation-flotation. The results of the micro-flotation experiment showed that cuprite recovery is related to the particle size, and that an excessive content of fine particles(<18 μm) impacted the recovery of coarse particles. When hydrophobic flocculation pretreatment was used, the recovery of fine cuprite in sulfidation-flotation increased from 60.3% to 86.3% under optimum conditions(pH 9.5; sodium oleate concentration, 2 × 10^(-4) mol×L^(-1); stirring time, 6 min; stirring speed, 1600 r×min^(-1)). The laser particle size analysis and optical microscopy results indicate that hydrophobic flocculation pretreatment effectively reduces the content of fine cuprite, and augments the apparent particle size in the pulp. We performed the Derjaguin–Landau–Verwey–Overbeek(DLVO) theory and extended DLVO theory calculations to further support the interpretation of the results.

Research on new beneficiation process of low-grade magnesite using vertical roller mill

We investigated whether the vertical roller mill can be efficiently used in the beneficiation of low-grade magnesite and whether it can improve upon the separation indices achieved by the ball mill.We conducted experiments involving the reverse flotation and positive flotation of low-grade magnesite to determine the optimum process parameters,and then performed closed-circuit beneficiation experiments using the vertical roller mill and ball mill.The results show that the optimum process parameters for the vertical roller mill are as follows:a grinding fineness of 81.6wt%of particles less than 0.074 mm,a dodecyl amine(DDA)dosage in magnesite reverse flotation of 100 g·t?1,and dosages of Na2CO3,(NaPO3)6,and NaOL in the positive flotation section of 1000,100,and 1000 g·t?1,respectively.Compared with the ball mill,the use of the vertical roller mill in the beneficiation of low-grade magnesite resulted in a 1.28%increase in the concentrate grade of MgO and a 5.88%increase in the recovery of MgO.The results of our causation mechanism analysis show that a higher specific surface area and greater surface roughness are the main reasons for the better flotation performance of particles ground by the vertical roller mill in the beneficiation of lowgrade magnesite.

Effect and mechanism of siderite on reverse flotation of hematite

The effects of siderite on reverse flotation of hematite were investigated using micro flotation, adsorption tests, and Fourier transform infrared spectroscopy. The flotation results show that interactions between siderite and quartz are the main reasons that siderite significantly influences the floatability. The interactions are attributed to dissolved siderite species and fine siderite particles. The interaction due to the dissolved species is, however, dominant. Derjaguin-Landau-Verwey-Overbeek（DLVO） theoretical calculations reveal that adhesion on quartz increases when the siderite particle size decreases and that fine particles partly influence quartz floatability. Chemical solution calculations indicate that the dissolved species of siderite might convert the surface of active quartz to CaCO_3 precipitates that can be depressed by starch. The theoretical calculations are in good agreement with the results of adsorption tests and FTIR spectroscopy and explain the reasons why siderite significantly influences reverse flotation of hematite.

New insights into the flotation responses of brucite and serpentine for different conditioning times: Surface dissolution behavior

The inadvertent dissolution of gangue minerals is frequently detrimental to the flotation of valuable minerals.We investigated the effect of conditioning time on the separation of brucite and serpentine by flotation.By analyzing the Mg2+concentration,relative element content,and pulp viscosity,we studied the effect of mineral dissolution on brucite flotation.The results of artificially mixed mineral flotation tests(with-10μm serpentine)showed that by extending the conditioning time from 60 to 360 s,a large amount of Mg2+on the mineral surface gradually dissolved into the pulp,resulting in a decreased brucite recovery(from 83.83%to 76.79%)and an increased recovery of serpentine from 52.12%to 64.03%.To analyze the agglomeration behavior of brucite and serpentine,we used scanning electron microscopy,which clearly showed the different adhesion behaviors of different conditioning times.Lastly,the total interaction energy,as determined based on the extended DLVO(Derjaguin-Landau-Verwey-Overbeek)theory,also supports the conclusion that the gravitational force between brucite and serpentine increases significantly with increased conditioning time.

Solution chemistry of carbonate minerals and its effects on the flotation of hematite with sodium oleate

The effects of carbonate minerals（dolomite and siderite） on the flotation of hematite using sodium oleate as a collector were investigated through flotation tests, supplemented by dissolution measurements, solution chemistry calculations, zeta-potential measurements, Fourier transform infrared（FTIR） spectroscopic studies, and X-ray photoelectron spectroscopy（XPS） analyses. The results of flotation tests show that the presence of siderite or dolomite reduced the recovery of hematite and that the inhibiting effects of dolomite were stronger. Dissolution measurements, solution chemistry calculations, and flotation tests confirmed that both the cations（Ca^（2＋） and Mg^（2＋）） and CO_3^（2＋）ions dissolved from dolomite depressed hematite flotation, whereas only the 23CO-ions dissolved from siderite were responsible for hematite depression. The zeta-potential, FTIR spectroscopic, and XPS analyses indicated that Ca^（2＋）, Mg^（2＋）, and CO_3^（2-）（HCO_3^-） could adsorb onto the hematite surface, thereby hindering the adsorption of sodium oleate, which was the main reason for the inhibiting effects of carbonate minerals on hematite flotation.

Improved flotation performance of hematite fines using citric acid as a dispersant

In this study, citric acid was used as a dispersant to improve the flotation performance of hematite fines. The effect and mechanism of citric acid on the reverse flotation of hematite fines were investigated by flotation tests, sedimentation experiments, scanning electron microscopy（SEM）, zeta-potential measurements, and X-ray photoelectron spectroscopy（XPS）. The results of SEM analysis and flotation tests reveal that a strong heterocoagulation in the form of slime coating or coagulation in hematite fine slurry affects the beneficiation of hematite ores by froth flotation. The addition of a small amount of citric acid（less than 300 g/t） favorably affects the reverse flotation of hematite fines by improving particle dispersion. The results of sedimentation experiments, zeta-potential measurements, and XPS measurements demonstrate that citric acid adsorbs onto hematite and quartz surfaces via hydrogen bonding, thereby reducing the zeta potentials of mineral surfaces, strengthening the electrical double-layer repulsion between mineral particles, and dispersing the pulp particles.

Synthesis and formation mechanism of micro/nano flower-like MgCO_3·5H_2O

Micro/nano magnesium carbonate pentahydrate（MgCO3 ·5H2 O） with flower-like morphology was synthesized using magnesite as a substrate and potassium dihydrogen phosphate as an additive. The synthesized samples were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetry and differential scanning calorimetry. The influence of pyrolysis time on crystal morphology was explored. The formation mechanism was investigated on the basis of the characterized results and the crystal structure of MgCO3 ·5H2 O. The results showed that the flower-like MgCO3 ·5H2 O was 1.5-3.0 μm in length and 100-500 nm in diameter and was successfully obtained with a pyrolysis time of 30 min. The formation mechanism of flower-like MgCO3 ·5H2 O is suggested to be the selective adsorption of potassium dihydrogen phosphate on the surface. The process of flower-like crystal growth is as follows： amorphous nanoparticles formation, acicular and rod monocrystal formation, flower-like monocrystal formation, and flower-like polymers（MgCO3 ·5H2 O） crystallization. In the MgCO3 ·5H2 O crystal, the magnesium ion presents two different octahedral coordinations corresponding to2 26 Mg（H O）＋and2 2 2 4 23 [Mg（H O）（CO） ]--, and the chemical formula of the crystal is2 2 6 2 4 23 Mg（H O） Mg（H O）（CO）2.

Structure–activity relationship and mechanisms of reagents used in scheelite flotation

Effects of carboxylic acid collector, benzohydroxamic acid (BHA), sodium hexametaphosphate (SHAP), sodium silicate, and oxalic acid on scheelite flotation were studied through flotation tests, quantum chemical calculation, and flotation solution computational chemistry. In terms of the calculation results, the relationship between chemical reactions occurring on the scheelite surface and molecular structures of the reagents were analyzed. The results show that BHA and carboxylic acid collectors interact with scheelite in different forms and the recovery of scheelite using sodium oleate as collector declines successively from SHAP, sodium silicate, to oxalic acid. Moreover, it is found that the performance of depressant in scheelite flotation is directly related to the group electronegativity, indicating that the latter is a dominant factor that determines the former. These findings will be helpful to the academic research communities of scheelite flotation.

Optimization and mechanism of gold-bearing sulfide flotation

In order to overcome the difficulty of extracting gold from gold-bearing sulfide ore by cyanide process flotation was adopted based on mineralogical analysis Mineralogy shows that gold particles are of superfine structure and mainly enclosed by sulfide ores. Primary gold-bearing sulfide ore is fine-grained pyrite and arsenopyrite. The paper describes the effects of ratios and dosage of activators and collectors on the recovery and grade of gold concentrate. A proper flotation flowsheet was then proposed based on experimental condition and closedcircuit test. The gold concentrate with the gold grade of25.14 g ton-1and the recovery of 86.94 % is obtained after one rougher, three cleaners, and four scavengers from fine grinding flotation process. Furthermore, the mechanisms of combined activators and combined collectors were studied by thermodynamic calculation, and structure-activity relationship of flotation reagent was also explained