Flotation Results Research Articles

Selective flotation of scheelite from calcite using a novel self-assembled collector

Both being Ca-bearing minerals, scheelite and calcite cannot be well separated by froth flotation due to their similar surface properties. To date, there is no report that scheelite and calcite can be well separated using collectors alone (including traditional NaOL and selective Pb-BHA complexes). Therefore, in this study, Pb(NO3)2, benzohydroxamic acid, and sodium oleate with specific combination (Pb-BHA-NaOL) were firstly used to form a novel collector to selectively separate scheelite and calcite. The flotation results of single and binary mixed minerals showed that the mixture of Pb, BHA and NaOL (molar ratio 6:6:1) exhibited excellent separation selectivity for scheelite and calcite at pH 9.0. Zeta potential measurements indicated that the dominant species of Pb-BHA-NaOL were positively charged and had stronger adsorption on negatively charged scheelite surfaces. Infrared spectroscopy and X-ray photoelectron spectroscopy further showed that Pb-BHA-NaOL had strong chemical interaction with Ca sites in the form of Pb(OH)-BHA-OL−, especially with O sites in the form of Pb-BHA+ on scheelite, but had no interaction with O sites on calcite. Therefore, the novel collector proposed in this work can provide a meaningful guide for the design of other novel collectors and have potential application prospects in scheelite flotation.

Sensitivity of oil shale particle surface to the applied load in ball mill

ABSTRACT The size reduction is a mandatory step in oil shale processing. In this study, the sensitivity of oil shale and its organic matters to the applied load in grinding was tested in a ball mill not only by using the different number of grinding media balls as an effective load but also by using balls made of two materials, namely, steel and ceramic. The ground product was characterized in terms of its mean size (d50) as well as it was subjected to flotation tests, and the properties of the floating product in terms of the loss-on-ignition and recovery percentages were determined. Furthermore, the Fourier transform infrared (FTIR) was used to show how the grinding media load can affect the surface properties of the ground product and correlate that to the flotation results. The results indicated that a delicate grinding load is needed for this sample of oil shale. The higher the load, the lower the loss-on-ignition (LOI) of the ground product and the lower the d50 of the ground product, and its higher recovery in flotation proposes that the produced fines are rich in gangue minerals of inorganic nature.

New evidence for supplementary crop production, foddering and fuel use by Bronze Age transhumant pastoralists in the Tianshan Mountains

The nature of economies and the movement of agricultural crops across Eurasia in the Bronze Age have been the subject of significant research interest in recent years. This study presents and discusses new results of flotation, radiocarbon and carbon stable isotope analyses from the seed assemblage at the Adunqiaolu site (northwestern Xinjiang), in combination with archaeological evidence. Archaeobotanical evidence, including carbonized foxtail millet, broomcorn millet, and naked barley, documents the diversity of local cereal consumption during the mid-second millennium BC. Our results suggest that crops were not grown locally, however, but in the lower Boertala Valley, supporting the argument that Adunqiaolu was a winter camp. These new sets of data constitute an important contribution to the discussion on cereal dispersal across the Tianshan Mountains in the Bronze Age.

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.

Recovery of Coal Values from Middling and Rejects by Froth Flotation and Mozley Mineral Separation

The recovery of coals values from Middling and Rejects carries out by using Froth flotation and Mozley Mineral Separation. The middling and rejects are the waste products from gravity beneficiation process, it has been noted that most of washery plants are selling this product at low cost because they have less values.The independent variables selected for Mozley Mineral Separator and their ranges were indicated in the parentheses as follow, water flow rates (400, 600, 800ml/s), amplitude (1.25, 1.5, 1.75inch) and collection time (30, 40, 60 s) while the independent variables for froth flotation were; Pulp density (10, 12.5, 15 %), collector dosage (39.3, 44.4, 49.5 g/t) and frother dosage (61.8, 65.3, 68.8 g/t). The number of experimental runs and regression equation determined by using Design Expert softwareThe d80 for middling and rejects samples were 10.5mm and 12.89mm respectively. The ash contents for the middling sample treated by froth flotation decrease from 37% to 15.85% at the reagent concentration of 49.5g/t collector, 65.3g/t frother and pulp density of 10%. The froth flotation results of middling sample shown to have a great reduction of ash contents. The overall optimum middling recovery and yield for washery grade I and II attain at reagent concentration and pulp density of 47.703g/t, 68.568g/t and 13.2% for collector, frother and pulp density respectively. The feed of reject coal was 71% and the ash contents reduced to 28.87% with the recovery of 0.85%. The analysis through Mozley mineral separator did not show significant changes in the reduction of ash from both middling and rejects. The ash contents achieved were above the scope of the studies for recovering of coal values. The experiments for middling and reject by froth flotation and Mozley mineral separator may be carried out by varying other parameters as well as the type of methods.

Theoretical and experimental investigation of disodium carboxymethyl trithiocarbonate in Cu-Mo flotation

As ore grades in the mineral industry decrease and ores become more complex and polymetallic, froth flotation becomes increasingly important in separating and producing a saleable product. In the chalcopyrite-molybdenite flotation industry, depressants are critical in achieving the necessary metal separation. NaHS is the predominant reagent used to depress copper and iron sulfides and thereby enable molybdenum flotation recovery and grade. However, these inorganic reagents have increasing regulations governing their use and have high consumption rates collectively meaning that the use of alternative reagents, especially organic depressants, is needed. Disodium Carboxymethyl Trithiocarbonate (Orfom® D8) is one such organic depressant. This study will report on research conducted with Orfom® D8 including bench-scale flotation as well as simple kinetic test (SKT) flotation of bulk chalcopyrite-molybdenite concentrate obtained from an operating North American process. Density Function Theory (DFT) molecular modeling and zeta potential measurements of pure chalcopyrite (CuFeS2) and molybdenite (MoS2) samples were used to help corroborate the flotation results.

Selective separation of scheelite from calcite using tartaric acid and Pb-BHA complexes

The calcite content severely restricts the flotation of scheelite in tungsten ores. Previous researches have proven the surface transformation between fluorite and calcite could promote the selective flotation of scheelite from other calcium-containing minerals when the lead complexes of benzohydroxamic acid (Pb-BHA) were employed as collector. However, given the increasing content of calcite in tungsten ores, it’s hard to obtain qualified scheelite concentrate with only Pb-BHA, so developing highly selective depressants to combine with Pb-BHA is necessary. Here, tartaric acid (TA) and Pb-BHA were used for the flotation of scheelite from calcite. Current flotation results showed that this reagent scheme (TA and Pb-BHA) could effectively separate scheelite from calcite. The zeta potential measurements and X-ray photoelectron spectroscopy analysis revealed the adsorption of TA on the calcite surface is much stronger than that on the scheelite surface. Crystal chemistry analysis demonstrated that the distance between the TA functional groups and calcium distance on the calcite surface matched better than that on the scheelite surface, which may directly contribute to the high selectivity of TA. In addition, zeta potential and infrared spectrometric analysis demonstrated that the Pb-BHA adsorption on the calcite surface was significantly impacted by TA, but Pb-BHA still could be intensively absorbed on the scheelite surface after interaction with TA.

Depression mechanism of environment-friendly depressant dithiocarbamate chitosan in flotation separation of Cu-Zn sulfide

The depressant performance and mechanism of dithiocarbamate chitosan (DTC-CTS) in flotation separation of chalcopyrite and sphalerite were investigated by micro-flotation experiment, UV–vis (UV–vis) spectrophotometer determination, time of flight secondary ion mass spectrometry (ToF-SIMS) test and local electrochemical impedance spectroscopy test (LEIS). The flotation results of Cu-Zn (1:1) mixed sulfide showed that chalcopyrite can be effectively separated from sphalerite using DTC-CTS as depressant and butyl xanthate as collector. The optimum conditions for flotation separation of chalcopyrite from the Cu-Zn sulfide were as follows: the dosage of DTC-CTS of 0.4 mg/L, butyl xanthate of 1 × 10−5 mol/L and flotation pH of 10. Copper concentrate with Cu grade of 31.93% and recovery of 85.97%, Zn grade of 4.82% and recovery of 4.18% can be obtained under the above conditions in the Cu-Zn sulfide flotation system. The results of ToF-SIMS showed that DTC-CTS can adsorb on both chalcopyrite and Cu-activated sphalerite surfaces, and the adsorption capacity on the two surfaces is roughly equivalent. UV–vis Spectrophotometric determination and LEIS results indicated that DTC-CTS strongly blocks the subsequent collector adsorption of butyl xanthate on sphalerite surface, but has little effect on the adsorption of butyl xanthate on chalcopyrite. Such difference of collector adsorption on chalcopyrite and sphalerite surfaces differs the surface hydrophobic and further results in the selective separation of chalcopyrite from Cu-Zn sulfide ore.

Effects of pyrite on the flotation behavior and electrochemical interaction of different particle sizes of galena in the presence of diethyldithiocarbamate

ABSTRACT Lead is widely used metals and pyrite is usually associated with galena. In addition, galena is prone to super-crushing during the grinding process. In this study, the galvanic interaction between different particle sizes of galena and pyrite were studied by electrochemistry, adsorption test and flotation test, respectively. Adsorption tests and microflotation tests indicated the recovery of galena of different sizes in mixed ore was decreased 5%–15% compared with single galena flotation results. The results of electrochemical measurement pointed out that the presence of pyrite enhances the corrosion rate of galena, and the finer the galena particles were, the stronger the electrochemical corrosion effect with pyrite became.

Flotation Behavior and Synergistic Mechanism of Benzohydroxamic Acid and Sodium Butyl-Xanthate as Combined Collectors for Malachite Beneficiation

Sulfuration flotation is the most widely used technology in malachite beneficiation. However, the inhomogeneity of malachite surfaces usually results in a non-uniform sulfuration surface. The motivation of this work is attempt to adopt different functional combination collectors to enhance the sulfuration flotation of malachite. Accordingly, the flotation behaviors and adsorption mechanisms of benzohydroxamic acid (BHA) and sodium butyl-xanthate (SBX) on the surface of malachite were systematically investigated using flotation tests, zeta-potential measurements, Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, and first-principle calculations. The test results of vulcanization flotation showed that the combined collectors of SBX with BHA possessed a higher recovery than only using SBH by 20%, indicating that there may be a synergistic effect between BHA and SBX. The IR and Raman spectroscopy demonstrated that both BHA and SBX could chemically adsorb onto the malachite surface. The density functional theory (DFT) calculation results further indicated that the combined adsorption energy of BHA and SBX was much lower than that of only BHA or SBX, which confirmed the synergistic effects of BHA and SBX on the malachite surface. This work may shed new light on the design and development of more efficient combined flotation reagents.

Electrochemical conditioning of recycled flotation wastewater for flotation results improving

Flotation of minerals, an important part of the chain of metals production for our society, needs huge amounts of water. This industry can contribute to the sustainable use of water and circular economy development by utilizing its own production wastewater. However, reuse of clarified water without additional treatment may cause worsening of flotation results. Electrocoagulation of this water with mild steel sacrificial anodes, complemented by electroflotation is able to decrease the chemical oxygen demand (COD) and dissolved organic carbon (DOC) of the treated water, i.e. to remove at least partially the residual organic reagents. For the studied case 66 % of COD and nearly 32 % of DOC were removed by electrocoagulation with mild steel electrodes at energy consumption of 0, 458 kWh/m3. This warrants better results of lead-zinc flotation carried out with treated water, in comparison to the case of use of untreated water, and contributes to freshwater saving. Treated water ensured outcomes of lead-zinc flotation comparable to the results found at use of fresh tap water.

Influence of hydrodynamic cavitation pretreatment on coal flotation

The flotation of fine coal particles has been a long-standing challenge in coal processing industry. In this study, the influence of hydrodynamic cavitation pretreatment (HCP) on coal flotation was investigated. A special HCP experiment system was designed for the conditioning of pulp based on the cavitation phenomenon through a venturi tube. Flotation results indicate that, compared with the conventional flotation method, HCP increases combustible recovery of concentrate by about 5%, besides, 50% collector dosage or 25% frother dosage can be saved with HCP under the same combustible recovery of concentrate. Meanwhile, HCP enhances the flotation rate constant by 9.41%. The sieving analysis of flotation products reveals that HCP flotation has a better response for fine coal particles relative to that of coarse coal particles. The bubble observation tests confirm the existence of micro-nano bubbles generated by HCP and the selective generation of micro-nano bubbles on the surface of coal. In addition, HCP leads to an obvious improvement of dispersion of collector. The aggregation of fine coal particles caused by HCP is another important contribution for the coal flotation. [Received: May 18, 2019; Accepted: March 28, 2020]

In-situ study of the kinetics of phosphoric acid interaction with calcite and fluorapatite by Raman spectroscopy and flotation

In the reverse anionic flotation of phosphate ores using phosphoric acid, it is often suggested that a selective surface passivation of the phosphate minerals by calcium phosphate occurs. Several calcium phosphate species have been proposed in the literature for this surface passivation. In this study, in-situ Raman spectroscopy was used to monitor as a function of time the interaction of phosphoric acid with calcite and fluorapatite at a fixed pH of 4.5 or at fixed phosphoric acid concentrations in order to identify what species have formed in conditions similar to those used in flotation. X-ray photoelectron spectroscopy was also used to confirm and identify more clearly the species formed at the minerals surface. Although a calcium phosphate (1:1) species was observed on both minerals, its presence on calcite was highly dependent on phosphoric acid concentration and pH as the latter controls both calcium dissolution and calcium phosphate precipitation. The results of mineral flotation have confirmed the importance of phosphate concentration in solution, originating from phosphoric acid addition and/or mineral dissolution, in the formation/precipitation of calcium phosphate which can turn on or off the flotation of calcite or fluorapatite, or both.

Effects and Mechanisms of Grinding Media on the Flotation Behavior of Scheelite.

Grinding, an essential procedure for size reduction and fresh surface exposure of mineral particles, plays an important role in mineral flotation. The grinding media are the key factors for effective grinding and thus for successful flotation. In this study, ceramic ball (CB) and cast iron ball (CIB), two representative grinding media, were chosen to investigate the effects and mechanisms of grinding media on the flotation behavior of scheelite. The results of pure scheelite flotation show that scheelite ground by CB has a better floatability than that ground by CIB. Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) analyses indicate that there are Fe species, namely, elemental iron (Fe), ferrous oxide (FeO), and iron oxyhydroxide (FeOOH), coated on the surfaces of scheelite ground by CIB but not in the case of scheelite ground by CB. The dissolved oxygen (DO) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) tests show that Fe ions exist in the CIB grinding slurry but not in the case of CB grinding slurry. Compared with the CB grinding slurry, the CIB grinding slurry has a lower DO content and higher Ca ion concentration. Zeta potential results reveal that the Fe species in the CIB grinding reduce the NaOl adsorption on the scheelite surfaces. Finally, the deleterious effect of CIB grinding on the flotation behavior of scheelite is verified by the actual scheelite ore flotation experiments.

Synthesis of 1-(2-Hydroxyphenyl) Dec-2-en-1-One Oxime and Its Flotation and Adsorption Behavior for Malachite.

A novel collector of 1-(2-hydroxyphenyl) dec-2-en-1-one oxime (HPDO) was synthesized from 2-hydroxy acetophenone and octanal, and its flotation and adsorption behavior for malachite were studied by flotation tests and x-ray photoelectron spectroscopy (XPS) analysis. The flotation results of a single mineral show HPDO is a special collector for malachite. Compared with benzohydroxamic acid (BHA), isobutyl xanthate (SIBX), and dodecylamine (DA), HPDO exhibits excellent flotation performance for malachite and satisfied selectivity against quartz and calcite over a wide pH range. The HPDO with a concentration of 200 mg/L can float 94% malachite at pH 8, while only recovering 7.8% quartz and 28% calcite. XPS data give clear evidence for the formation of a Cu-oxime complex on malachite surfaces after HPDO adsorption.

Derivation of Flotation Kinetic Model for Activated and Depressed Copper Sulfide Minerals

The wettability and floatability of oxidized chalcocite, bornite, and chalcopyrite with the conditions of sodium hydrosulfide (NaHS) dosages and pHs were studied by contact angle measurements, and single and mixture mineral flotation tests. To evaluate the results of the flotation, the flotation kinetic model for copper sulfide minerals treated by NaHS was derived. In this study, we focused on the activation and depression by NaHS, a well-known activator and depressant of copper minerals. The flotation results showed that there can be a threshold NaHS dosage to activate the mineral surfaces, as evidenced by the depression of the minerals and reduction of recoveries at higher dosages of NaHS. Chalcocite recoveries increased with an increase of NaHS dosage. Bornite recoveries tended to be depressed with a smaller amount of NaHS as pH increased. The recoveries of chalcopyrite increased as pH increased at an optimum NaHS dosage. Moreover, the flotation kinetic model that includes the surface properties and the reaction rate constant between the copper sulfide minerals and NaHS was derived. The trends of the flotation rate constants and mass fractions with NaHS dosages and pHs could quantitatively well-explain the flotation results.

Optimizing oxidized coal flotation using impact flow conditioning pulp

ABSTRACT Numerous oxygen elements are present on the oxidized coal surfaces, resulting in the difficulties for flotation. In this study, the enhancement of oxidized coal flotation using the impact flow conditioning pulp was investigated, and the impact flow velocity was optimized. The enhancement mechanism of the impact flow conditioning pulp was investigated via a series of experiments. The results showed that the use of impact flow conditioning pulp could improve the cumulative combustible recovery and flotation kinetics of oxidized coal, and these increased with the increasing impact flow velocity. In the experimental range, an optimum flotation result was obtained at an impact flow velocity of 5 m/s. The SEM analysis showed that the impact flow conditioning pulp could remove the aggregations on the oxidized coal surface, exposing a fresh surface. The XPS analysis confirmed that the impact flow conditioning pulp could increase the carbon contents and decrease the oxygen contents on the oxidized coal surface. Further, the impact flow conditioning pulp could significantly enhance the hydrophobicity and floatability of oxidized coal.

Investigation of nanobubble enhanced reverse anionic flotation of hematite and associated mechanisms

Hematite is commonly upgraded in China using a reverse anionic flotation process with starch as depressant for hematite, Ca2+ as activator and fatty acids as collector for quartz. The Anshan type of hematite is well known for its low grade, fine dissemination, difficulty in upgrading, and huge reserve in China. To investigate effects of nanobubbles and different reagents on the flotation process of this particular hematite, batch flotation tests were conducted with a mechanical flotation cell integrated with a cavitation device that generates nanobubbles under different process parameters including corn starch dosage, lime (CaO) dosage, collector dosage, and air flow rate through the nanobubble generator. Significant improvements in hematite flotation performance was achieved in the presence of nanobubble. The nanobubble flotation results and associated mechanisms are discussed based on up-to-date chemistry of hematite flotation and unique nanobubble characteristics.

Synergistic collection mechanism of D-phenylalanine and sodium oleate in flotation of diaspore from kaolinite

Mixed collectors were widely used in mineral flotation. In this work, D-phenylalanine (D-phe) was first introduced to improve the collectability and selectivity of sodium oleate (NaOL) for diaspore from kaolinite. The flotation performance of diaspore and kaolinite were studied by micro-flotation tests, and the synergistic mechanisms of D-phe with NaOL were investigated through FTIR spectra, zeta potential, solution chemistry and X-ray photoelectron spectroscopy (XPS). Single and mixed flotation results show that D-phe exhibited superior synergism power with the NaOL collector. Under pulp pH 9.0, the flotation recovery of diaspore was increased from 77.13% to 91.07%, while that of kaolinite was decreased from 16.27% to 13.75%. The zeta potential and XPS analysis indicate that the synergistic mechanisms of D-phe with NaOL were mainly the co-adsorption via the carboxylate group of D-phe and NaOL bonding with the Al sites of diaspore surface. D-phe was chelated onto the diaspore surface through the –COO– and –NH3+/NH2 groups, and the pre-adsorption of D-phe could increase the Al active sites of diaspore surface for the direct adsorption of NaOL. NaOL could also indirectly adsorb on the diaspore surface through H-bonding with –NH2/NH3+ groups of D-phe.

Selective Flotation of Scheelite from Calcite Using a Novel Reagent Scheme

ABSTRACT Scheelite and calcite are usually intergrown calcium minerals that are separated via froth flotation. However, their selective separation remains difficult because of their similar surface properties. 2-phosphonobutane −1, 2, 4-tricarboxylic acid (PBTCA or H5L) is widely used in water treatment due to its low phosphorus content and efficient anti-scaling performance. With its excellent calcium-chelating ability, PBTCA was used as a novel depressant to selectively separate scheelite from calcite in this study. The flotation results of single mineral, binary mixed minerals, and real ore showed that PBTCA could selectively depress calcite at pH 9.0 using sodium oleate as collector. The results of zeta potential measurements, solution chemistry calculation, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculation indicated that the dominant form of PBTCA was L5-. This anion had a stronger adsorption on negatively charged calcite surfaces through electrostatic interaction. Higher Ca density and stronger Ca activity on calcite promote the adsorption of L5-. Moreover, the active O atoms in L5- could better match with two Ca sites on calcite in the interatom distance. Thus, PBTCA provides a new option for calcite depressants and has great industrial application potential.