Flotation Separation Of Scheelite Research Articles

Surface pretreatment of scheelite and cassiterite by gallic acid to achieve high efficiency flotation separation

Scheelite and cassiterite are common tungsten and tin oxide minerals that often coexist in nature. However, the similar oxidation degrees and solution and surface chemical properties of scheelite and cassiterite pose challenges to their flotation separation. Moreover, research in this area is currently limited. This study investigated the selective depression mechanism of gallic acid (GA) in the flotation separation of scheelite and cassiterite and successfully achieved the effective separation of the two minerals. Single mineral and artificially mixed mineral experiments were performed to analyze the flotation separation behavior of scheelite and cassiterite. The results revealed that in the absence of a depressant, scheelite and cassiterite exhibited recovery of 93.43 % and 89.72 %, respectively. After the addition of 5 × 10−4 mol/L GA to the mineral slurry, the grades of WO3 and Sn in the flotation concentrates were 48.93 % and 18.13 %, with recovery of 82.50 % and 31.62 %, respectively. Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, zeta potential, adsorption amount, contact angle, and atomic force microscopy imaging analyses were conducted to examine the selective depression mechanism of GA in the flotation separation of scheelite and cassiterite. In the slurry, the cassiterite surface provided active Sn sites for the chemical adsorption of GA. Moreover, the phenolate O- donor atoms of the deprotonated polar groups of GA will undergo coordination with metal ions and then adsorb on the mineral surface. GA forms metal gallate through adsorption of its –COOH and –OH groups on mineral surface and produces textured oxide layer rich in OH groups, thus reducing the surface hydrophobicity of cassiterite and then depressing cassiterite. The selective adsorption of GA on the cassiterite surface hindered the further adsorption of NaOL, thereby reducing its surface hydrophobicity. Therefore, GA finally realized the flotation separation of the two minerals.

Mechanistic analysis and validation of an efficient novel inhibitor for scheelite and calcite flotation separation: A DFT and MD simulation study

Due to the similar surface characteristics of scheelite and calcium-bearing minerals, the efficient utilization of scheelite has become a current research focus. This study investigated a novel inhibitor, phosphonic carboxylic acid copolymer (POCA), and explored its influence on the flotation separation of scheelite and calcite in a sodium oleate collector system. The flotation experiments demonstrated that 3 mg/L POCA can effectively inhibit the flotation of calcite. The results of zeta potential and Fourier transform infrared spectroscopy (FTIR) indicate the emergence of a novel carboxyl (C = O) characteristic peak in the infrared spectrum of calcite following the introduction of POCA. This suggests that the interaction between POCA and the calcite surface occurs via chemical adsorption. Additionally, a markedly negative shift in the surface potential of calcite is observed, suggesting that this interaction is more robust compared to the interaction with scheelite. Density functional theory (DFT) and molecular dynamics (MD) simulations suggest that POCA can chemically adsorb onto the Ca site on the calcite surface through the –SO3H and –PO3H2 functional groups, simultaneously enhancing the hydrophilicity of the calcite surface to a certain degree.

Flotation separation of scheelite from calcite using luteolin as a novel depressant

Flotation separation of scheelite from calcite using luteolin as a novel depressant

Enhanced separation of scheelite and calcite by metal-inorganic complex depressant

The effect of metal-inorganic complex depressant composed of aluminum sulfate and sodium silicate (AlSS) on the flotation separation of scheelite and calcite was studied. Zeta potential and adsorption measurements confirmed that the negatively charged colloidal particles composed of Al(OH)4− and SiOm(OH) n4−2m−n tended to be adsorbed on calcite surface, inhibiting the adsorption of sodium oleate (NaOL), while the adsorption of negatively charged colloidal particles on scheelite surface was relatively low, which resulted in the great adsorption capacity of NaOL on scheelite. The contact angle measurements showed that the hydrophobicity of scheelite was significantly better than that of calcite in the NaOL+AlSS solution. XPS measurement results indicated the adsorption of Al and Si on the calcite surface rather than on the scheelite surface. Compared to adding water glass (sodium silicate, SS) only, the depression effect on calcite was significantly enhanced by the combination of AlSS, while scheelite flotation was hardly affected. Scheelite concentrate with WO3 grade of 68.34% and WO3 recovery of 83.14% could be obtained from mixed scheelite and calcite ores by adding AlSS.

Flotation separation of scheelite from fluorite by new depressant nitrilotriacetic acid and its mechanism

BackgroundFluorite and scheelite are main resources for fluorine and tungsten respectively, which are usually associated with each other, and the separation of them has important strategic meaning. For the first time, scheelite and fluorite were separated by using nitrilotriacetic acid (NTA) as depressant. MethodsThe effects of NTA on the flotation of scheelite and fluorite were investigated by flotation experiments. The selective adsorption mechanism of NTA on fluorite were revealed by atomic force microscope (AFM), zeta potential measurements, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Significant findingsNTA could achieve the efficient separation of scheelite from fluorite. Under the optimal separation conditions, the recovery of scheelite concentrate is 73.59 % and the grade of CaWO4 is 73.19 %, and the recovery and CaF2 grade of fluorite in tailings was 74.71 % and 79.44 % respectively. Mechanism study showed that although NTA had carboxy groups, NTA could not be adsorbed on scheelite surface due to the electrostatic repulsion and steric effect. However, NTA was strongly chemisorbed by calcium on fluorite, covering calcium groups and hiding the further adsorption of NaOL. Thus, NTA selectively disturbed NaOL adsorption and decreased the floatability of fluorite and realized the scheelite-fluorite separation.

Research Progress with Scheelite Flotation Reagents: A Review

With the depletion of easily mined and separated wolframite, scheelite has become the primary source of tungsten. Flotation is the primary technique used to enrich scheelite. However, flotation separation of scheelite from calcium-bearing gangue minerals, such as calcite and fluorite, has always been challenging due to their similar surface properties. To date, various flotation reagents and related mechanisms have been proposed for scheelite, which have attracted considerable attention. This paper reviews the scheelite flotation reagents, including collectors and regulators, and introduces recent research progress on the mechanisms for the interactions between the flotation reagents and mineral surfaces. The advantages and limitations of different flotation reagents are discussed. Inorganic or organic inhibitors in combination with fatty acids, chelate collectors, and cationic collectors are commonly used to separate scheelite from calcium-bearing gangue. Flotation differences between the scheelite and calcium-bearing minerals can be explained by variations in the electrical charges and steric hindrance at the mineral surfaces. In the future, fatty acid collectors will be still the main collectors used in scheelite flotation due to their low cost and strong collecting ability, and new collectors with high selectivity (such as metal complex collectors, new chelate collectors, new environmental collectors) will become a new research hotspot in the future due to their good selectivity.

Flotation separation of scheelite from calcite using baicalin as a depressant

In this study, the depressive effect and mechanism of baicalin (BAI), a flavonoid, in the flotation separation of scheelite and calcite was investigated. A series of surface analysis techniques were used to explain the selective depression mechanism of BAI on the calcite in flotation. The outcomes of the microflotation tests clearly demonstrated the selective depression of BAI on calcite in flotation separation. Under a pH of 9, dosage regimen of 20 mg/L BAI and 50 mg/L NaOL, the recovery rates were 82.24% for scheelite and 4.12% for calcite. Findings derived from contact angle measurements, adsorption tests, and zeta potential measurements that baicalin impeded the subsequent adsorption of sodium oleate onto calcite after interaction but had a lesser effect on scheelite. Furthermore, analysis of the FTIR spectra and XPS results revealed the selective adsorption of baicalin on the surface of calcite. The dominant component on the calcite surface was mainly positively charged calcium species, the hydroxyl group within the baicalin molecule could chelate react with the calcium plasmonic dots on the calcite surface, it resulting in a stronger chemisorption phenomenon on the calcite surface. But the dominant component on the scheelite surface was mainly negatively charged tungstate, it has less effect on its floatability. Under the inhibiting effect of BAI, the floatability difference between scheelite and calcite becomes larger, and finally achieving the flotation separation of the two minerals. Therefore, BAI is an environmentally friendly and efficient depressant.

Enhanced adsorption of citric acid at the calcite surface by adding copper ions: Flotation separation of scheelite from calcite

In this study, in light of the poor selectivity of single copper ions (Cu2+) and poor inhibition ability of citric acid (CA), the flotation separation effect of mixed depressant Cu2+/CA on scheelite and calcite was explored. The microflotation experiment showed that the mixed depressant had better separation effects on the two minerals than the single depressant, and the laboratory-scale experiment verified the efficient separation effect of the mixed depressant. The solution chemical analysis demonstrated the dominate components in the slurry environment. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis demonstrated the selective chemical co-adsorption of the mixed depressant in the form of copper species complexes on the calcite surface. The thermodynamic calculation of the complex formation and the conditional stability constant calculation prove that the copper species complex (CuL-) is more easily formed and more stable than the calcium species complex. The mixed depressant Cu2+/CA can efficiently separate scheelite and calcite, and scheelite can be efficiently enriched.

Camphor leaf extract as neoteric and environmentally friendly depressant in flotation separation of scheelite and calcite

Camphor leaves were directly extracted as depressants by using simple physical methods. The active ingredients and depression mechanism were studied through contact angle measurements, Fourier transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM). The flotation experiment showed that camphor leaf extract (CLE) had a strong depression effect on calcite but minimal effect on scheelite. The adsorption morphology detected using AFM confirmed the existence of active ingredients on calcite. FTIR results indicated that the adsorbed components on the surface of calcite contained a large number of hydroxyl groups that made calcite hydrophobic. Zeta potential measurements and FTIR revealed a much higher adsorption amount of CLE on the calcite surface than on the scheelite surface. The CLE has potential application value in the flotation separation of scheelite and calcite.

Application of a new amidoxime surfactant in flotation separation of scheelite and calcite: Adsorption mechanism and DFT calculation

With its high electrical conductivity, thermal creep resistance and compression modulus, tungsten take an irreplaceable position in modern industry, defense, and high technology. Scheelite, as the main raw material of tungsten resources, usually adopts Petrov’ process: steam heating 80 °C-90 °C, stirring in a tank containing 2%-4% sodium silicate solution for more than half an hour to make sodium oleate desorbed on the calcite surface, and repeated cleaning. Herein, a new amidoxime surfactant 3-dodecylamine propyl amidoxime (DPA), had been synthesized and used as a collector for the first time in the flotation separation of scheelite and calcite at room temperature without any sodium silicate, and compared with the traditional collector sodium oleate (NaOL). The flotation behavior of DPA was studied by micro-flotation and mixed binary mineral flotation tests, which showed that DPA has good collection ability and excellent selectivity for scheelite. Meanwhile, the interaction mechanism of DPA on the mineral surface was discussed by FTIR analysis, zeta potential test, contact angle measurement and density functional theory (DFT). FTIR analysis and zeta potential test confirmed that DPA collector had adsorption on scheelite surface but had little effect on calcite. DFT calculation further confirmed that the positively charged –C(NOH)N+H3 group in DPA had electrostatic adsorption on the negatively charged scheelite surface. The contact angle measurement results revealed that DPA can enhance the surface hydrophobicity of the scheelite particles. Therefore, this highly selective DPA surfactant can achieve effective separation of scheelite and calcite, contributing to environmental protection and sustainable green development of resources.

Study of the Effect of Manganese Ion Addition Points on the Separation of Scheelite and Calcite by Sodium Silicate.

The flotation separation (FS) of both scheelite and calcite minerals with similar physicochemical properties remains challenging, since the Ca active sites exist on their surfaces. The present work investigated the effects of different addition points of MnCl2 on the FS of scheelite and calcite by micro-flotation tests, zeta potential measurements, UV-Vis spectrophotometer measurements, infrared spectrum analysis, and X-ray photoelectron spectroscopy (XPS) tests, and the mechanism of separation is elucidated. Interestingly, the recovery of scheelite was 91.33% and that of calcite was 8.49% when MnCl2 was added after sodium silicate. Compared with the addition of MnCl2 before Na2SiO3, the recovery of scheelite was 64.94% and that of calcite was 6.64%. The sequence of adding MnCl2 followed by Na2SiO3 leads to the non-selective adsorption of Mn2+ on the surface of scheelite and calcite firstly, and later, sodium silicate will interact with it to produce hydrophilic silicate. This substantially enhances the hydrophilicity on the surface of both minerals, making separation impossible. In contrast, the addition of MnCl2 after sodium silicate can promote the formation of a metal silicate and enhance the selectivity and inhibition effect on calcite. Meanwhile, under this dosing sequence, the adsorption of Mn2+ on the scheelite surface offered more active sites for sodium oleate, which improved the scheelite surface hydrophobicity. This leads to a great improvement of the FS effect of scheelite and calcite.

Mechanism of manganese ion interaction with the surface of scheelite and calcite and its effect on flotation separation

Scheelite and calcite have similar surface physicochemical qualities and share the same calcium ion active sites in the mineral surface, making their separation more challenging. In this work, the effect of manganese chloride on the flotation separation of scheelite and calcite was explored utilizing flotation tests, Zeta potential tests, Fourier-transform infrared spectroscopy (FTIR), adsorption amount estimation, and X-ray Photoelectron Spectroscopy (XPS). The flotation test revealed that scheelite recovery increases gradually with increasing manganese chloride following manganese chloride addition, while the recovery of calcite gradually decreases. The recovery difference between the two minerals reached 82.84% points, achieving a better separation of scheelite and calcite. Manganese chloride produced manganese ions on the surface of scheelite, as confirmed by infrared spectroscopy, adsorption measurements, and X-ray Photoelectron Spectroscopy (XPS). Manganese ions were adsorbed on the surface of scheelite when manganese dichloride was added, increasing the number of cations on the surface and improving scheelite sodium oleate (NaOL) interaction. Furthermore, the addition of manganese ions increased the selectivity of sodium silicate, which increased its inhibition on the calcite surface, reducing sodium oleate adsorption on the calcite surface and thus reducing flotation recovery, achieving the goal of separating the two minerals.

Flotation Separation of Scheelite from Calcite Using Sulfonated Naphthalene–Formaldehyde Condensate as Depressant

In this paper, the potential of sulfonated naphthalene formaldehyde (SNF) condensate as a depressant in the flotation separation of scheelite from calcite was verified and investigated. The results of microflotation experiments showed that SNF had a stronger depressant performance on calcite than a conventional depressant—water glass and had an excellent performance in fine-grained particles (−0.037 mm) treatment. Adsorption tests were conducted to quantitatively study the selective adsorption of SNF on the surface of scheelite and calcite. At 200 mg/L SNF, the adsorption density of SNF on the calcite surface reached 5.48 mg/g, which was more than four times than that of scheelite. In addition, compared with scheelite, the adsorption of SNF on the calcite surface had a more significant negative effect on the contact angle. Moreover, infrared (IR) measurements combined with X-ray photoelectron spectroscopy (XPS) analysis were performed to investigate the adsorption mechanisms of SNF on scheelite and calcite surfaces. The results showed that the adsorption of SNF on scheelite was more likely to be physical attraction, while the –SO3− group in SNF could chemically react with Ca species on the surface of calcite, resulting in a stronger adsorption than on scheelite.

Unraveling roles of lead ions in selective flotation of scheelite and fluorite from atomic force microscopy and first-principles calculations

Metal ions are widely used to achieve selective hydrophobization of different mineral particles. However, the atomic understanding of the roles of metal ions is insufficient due to the limitation of experimental techniques. Herein, the in-situ atomic force microscopy (AFM) force curves and first-principles calculations were combined with the conventional experiments [i.e., batch flotation, zeta potential tests, and X-ray photoelectron spectroscopy (XPS)] to investigate the roles of lead ions (Pb2+) in flotation separation of scheelite and fluorite. The conventional experiments showed that Pb2+ could enhance the flotation recovery of scheelite but suppress fluorite. AFM force curves showed that, due to the presence of Pb2+, the interaction force between benzohydroxamic acid (BHA) and the scheelite surface was a stronger adhesion than the adhesion between BHA and fluorite without lead ions. First-principles calculations revealed that the strong electrostatic attraction resulted in the adsorption of BHA on fluorite surfaces. However, BHA could hardly bond with the scheelite surface with negative charges and hydroxylated Ca sites. The reaction between BHA and Pb2+ was the most favorable. The formed BHA-Pb complexes demonstrated repulsive interactions on fluorite surfaces but attractions on scheelite surfaces. Lead ions played as an inhibitor for fluorite flotation and an on-off switch for scheelite flotation. AFM and first-principles calculations have shown great potential in the analysis of the complicated interface interactions.

Effect of ultrasonication of sodium silicate on selective adsorption of scheelite and fluorite surfaces

Effect of ultrasound on solution properties of sodium silicate (Na2SiO3) was investigated in this study to separate scheelite from fluorite effectively. The effect of ultrasonicated sodium silicate solution on flotation separation of scheelite and fluorite and selective adsorption mechanism of scheelite and fluorite were also explored. Ultrasonicated Na2SiO3 was found to significantly improve the scheelite grade, and the adsorption capacity and adsorption heat of Na2SiO3 on fluorite surface were significantly improved, which can enhance the inhibitory effect. The ultrasonic cavitation effect promoted electrolysis of Na2SiO3 in the solution, forms additional SiO32− and SiO44− ions, reduced surface tension of the solution, and thus reduced adhesion work between Na2SiO3 and fluorite. Fourier transform infrared (FTIR) Spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses showed that sodium silicate was obviously adsorbed on the surface of fluorite, elemental Si content of the fluorite surface increased considerably and to a higher level than that of the scheelite surface, and Ca2+ binding energy shifted less noticeably on the scheelite surface than that on the fluorite surface. These results indicated that the higher adsorption strength for Na2SiO3 on the fluorite surface than that on the scheelite surface hindered the adsorption of benzohydroxamic acid (BHA) on the fluorite surface and ultrasound promoted selective separation of scheelite and fluorite.

Flotation separation of scheelite from fluorite by using DTPA as a depressant

The selective separation of scheelite from fluorite is difficult because of their similar surface properties. In this study, diethylenetriaminepentaacetic acid (DTPA) was used as a novel depressant for the efficient removal of fluorite from scheelite, and its depression effect and mechanism were systematically investigated by conducting micro-flotation experiments and a series of surface analyses. The micro-flotation experiments showed that the floatability of fluorite was significantly reduced by DTPA, whereas that of scheelite was minimally affected. Zeta potential measurements revealed that DTPA selectively adsorbed on fluorite surface and decreased the zeta potentials, whereas the zeta potentials of scheelite were negligibly influenced by DTPA. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy further proved that the interaction between DTPA and the fluorite surface was chemisorption, and in the adsorption configuration, the carboxyl groups of DTPA chelated with Ca sites on the fluorite surface. Additionally, an electrical analysis showed that electrostatic attraction facilitated the adsorption of DTPA on the fluorite surface. The adsorption of DTPA on fluorite surface could strongly inhibit the further adsorption of NaOL on fluorite surface, and therefore significantly depressed the floatability of fluorite. In contrast, the interaction between DTPA and scheelite was very weak and was impeded by steric hindrance caused by WO42- and electrostatic repulsion. Therefore, DTPA has the potential to act as a depressant for the effective separation of scheelite from fluorite.

Effects of Pb2+ ions on the flotation behavior of scheelite, calcite, and fluorite in the presence of water glass

Pb2+ ions and water glass are commonly used as the activator and depressant, respectively, in the flotation separation of scheelite from calcite and fluorite in industry. The interactive effects of Pb2+ ions and water glass are rarely reported. In this paper, the effects of Pb2+ ions on the flotation behavior of scheelite, calcite, and fluorite in the presence of water glass were investigated through single mineral flotation experiments, zeta potential measurements, solution chemistry calculations, and X-ray photoelectron spectroscopy (XPS) tests. The flotation results showed that at optimal conditions, Pb2+ ions could activate scheelite flotation and enhance the depression effects of water glass on the calcite and fluorite flotation compared with water glass alone. Solution chemistry calculations and zeta potential analysis indicated that after Pb2+ ions adsorption, water glass could strongly adsorb onto the calcite and fluorite surfaces and inhibit the NaOL adsorption, while on the scheelite surface, water glass could hardly adsorb and thus NaOL adsorption continued. XPS results further revealed that Pb2+ ions combined with WO bond to form the W-O-Pb2+ structure on the scheelite surface which could be the active sites for NaOL adsorption, while on the calcite and fluorite surfaces, the Pb-water glass polymers (polycondensation product of water glass and Pb2+ ions) and water glass combined with CaO bond to depress their flotation.

Flotation separation of scheelite and apatite by polysaccharide depressant xanthan gum

Tungsten is a crucial rare metal with extensive application in modern industries and scheelite is the major resource for tungsten production. In this work, xanthan gum (XG), a non-toxic, environmentally friendly polysaccharide, was explored as a depressant of apatite during the scheelite flotation. The results of single mineral flotation and artificial mixed minerals flotation showed that XG exhibited efficient selective depressive effect on apatite rather than on scheelite. The Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis indicated that the chelation action between the –COO– groups and the Ca on apatite surface was responsible for XG chelating adsorption. The firm XG chemisorption on apatite surface hindered subsequent sodium oleate (NaOl) chemisorption. Due to fewer available surface Ca sites and intenser anions group electronegativity on scheelite, the XG adsorption on scheelite surface was weak and it exhibited little effect on following NaOl chemisorption. As a result, the flotation separation of scheelite from apatite was achieved using XG as depressant and NaOl as collector.

Utilization of iron ions to improve the depressive efficiency of tartaric acid on the flotation separation of scheelite from calcite

Scheelite and calcite have similar surface physical and chemical properties and the same calcium ion active sites in the slurry. In order to achieve the flotation separation of the two minerals, high-efficiency flotation depressants are required. In this work, the mixed application of ferric ions (Fe3+) and small molecular organic chelating reagent tartaric acid (TA) was used to explore its depressive effect on the flotation separation of scheelite from calcite. The flotation separation effect of scheelite from calcite under the condition of mixed depressant Fe3+/TA was studied through microflotation experiments and artificial mixed mineral experiments. The selective adsorption mechanism of the mixed depressant on the two minerals was revealed by zeta potential experiments, solution chemical analysis, thermodynamic analysis, adsorption experiments and X-ray photoelectron spectroscopy (XPS) analysis. The flotation experiments indicated that the mixed depressant can efficiently realize the flotation separation of scheelite from calcite. The mechanism experiments revealed that the mixed depressant had a stronger co-adsorption on the surface of calcite. The pre-adsorption of iron ions provided much adsorption sites for the adsorption of depressant TA, which increased the adsorption amount of TA and iron ions on the surface of calcite, and it hindered the further adsorption of the collector sodium oleate (NaOL). The mixed depressant TA/Fe3+ adsorbed on the surface of calcite mainly existed preferentially in the form of the chelate FeL2−.

Effect of iron ions as assistant depressant of citric acid on the flotation separation of scheelite from calcite

The flotation separation of scheelite and calcite is challenging, because of the similarities in their surface chemical properties, solution chemical properties, calcium ion active sites, and, consequently, floatability. Efficient flotation depressants are required to separate scheelite and calcite by flotation. Citric acid (CA) has recently been investigated as a flotation depressant; however, its depressing action toward calcite is limited owing to its low number of polar groups (i.e., carboxyl and hydroxyl groups). In this study, iron ions (Fe3+) were used to improve the depressing action and selectivity of CA toward calcite. The microflotation behavior of scheelite and calcite was investigated under the influence of different depressant systems. Wettability, Fourier transform infrared, X-ray photoelectron spectroscopy, thermodynamic, and atomic force microscopy analyses revealed the selective depression mechanism of the depressant mixture comprising Fe3+ and CA (denoted Fe3+/CA). The microflotation results indicate that although the flotation separation of the two minerals is difficult using CA on its own, good separation effect is achieved using Fe3+/CA. Fe3+/CA chemically co-adsorbs on the calcite surface more strongly than on the scheelite surface. The iron ions and CA form ferric citrate (where L here denotes that the citrate ion is a ligand) that is then adsorbed at the oxygen sites on the surface of calcite in the flotation slurry. In the presence of Fe3+/CA, the adsorbed complexes form a dense layer on calcite, but a sparse layer on scheelite. The proposed depressant system realizes the efficient flotation separation of scheelite from calcite, which has theoretical and practical significance for the efficient development and utilization of scheelite resources.