Flotation Results Research Articles

Pico–nano bubble column flotation using static mixer-venturi tube for Pittsburgh No. 8 coal seam

The flotation process is a particle-hydrophobic surface-based separation technique. To improve the essential flotation steps of collision and attachment probabilities, and reduce the step of detachment probabilities between air bubbles and hydrophobic particles, a selectively designed cavitation venturi tube combined with a static mixer can be used to generate very high numbers of pico and nano bubbles in a flotation column. Fully embraced by those high numbers of tiny bubbles, hydrophobic particles readily attract the tiny bubbles to their surfaces. The results of column flotation of Pittsburgh No. 8 seam coal are obtained in a 5.08cm ID and 162cm height flotation column equipped with a static mixer and cavitation venturi tube, using kerosene as collector and MIBC as frother. Design of the experimental procedure is combined with a statistical two-stepwise analysis to determine the optimal operating conditions for maximum recovery at a specified grade. The effect of independent variables on the responses has been explained. Combustible material recovery of 85–90% at clean coal product of 10–11% ash is obtained from feed of 29.6% ash, with a much-reduced amount of frother and collector than that used in conventional column flotation. The column flotation process utilizing pico and nano bubbles can also be extended to the lower limit and upper limit of particle size ranges, minus 75μm and 300–600μm, respectively, for better recovery.

SELECTION OF SULFHYDRIL COLLECTORS FOR FLOTATION OF SULFIDES OF NONFERROUS METALS FROM REFRACTORY ORES OF NONFERROUS METALS

Methods of selection of selective collectors are analyzed. The procedure of calculation of characteristics of absolute rigidity, absolute electronegativity, and reaction ability of compounds is presented. The correspondence between the results of theoretical calculations of the reaction ability of sulfhydril collectors and experimental results of adsorption and flotation of monomineral fractions of chalcopyrite, galenite, and pyrite by sulfhydril collectors is revealed. The prediction of the collecting activity based on calculations is complicated by the features of the chemical composition of natural sulfides and defectiveness of the surface associated with the genesis of ore minerals in the deposit is revealed. Dithiophosphates and thionocarbamates are isolated as main components of selective compositions of collectors for flotation of pyrite ores of nonferrous metals based on theoretical and experimental investigations. It is shown by the complex of adsorption investigations in conditions of nonfrothing flotation and analysis of the IR frustrated total internal reflection (FTIR) spectra of concentrates of nonfrothing flotation that the nonoptimal ratio of components weakly active relative to pyrite leads to a considerable increase in pyrite floatability. Sorption of components of the sulfhydril collector and pyrite floatability increase with the fraction of a nonionogenic collector in the composition lower than 40–60%. The action mechanism, which determines the action selectivity of sulfhydril collectors during the flotation of sulfides, is determined.

PROCESSING ORES AND ANTHROPOGENIC CU–NI FEEDSTOCK WITH THE APPLICATION OF TECHNOLOGY OF JET AIR–STEAM FLOTATION

A method of flotation investigated, for which a mixture of air with saturated water steam is used as a gas phase. When steam contacts with liquid, the boundary layer of the bubble is heated due to heat of condensation, which is further spent for steam evaporation—the bubble is broadened and forces out the «hot» layer from the surface into the bulk, while its place is occupied by underheated liquid, and condensation repeats. The wave-like repetition of condensation↔evaporation processes determines the damping pulsations of the bubble surface, which varies the result of flotation. The flotation method by the air-steam mixture is used when concentrating the copper–nickel feedstock by the scheme «in two jets»: the crude concentrate of the first flotation jet is isolated from 1/2 part of the initial feedstock, it is mixed with another 1/2 part of ore, and ready crude concentrate of the second flotation jet is isolated using aerosol column flotation. When concentrating the ores of the Pechenga ratio (Russia) by the flow chart with the jet motion of the initial feeding and crude concentrate with the application of the air-steam mixture as the gas phase during the flotation, an increment in recovery of nickel was 2,93 % and copper – 3,22 %. The passage to the technology of jet air-steam flotation when concentrating dump slags of OAO MMC «Norilsk Nickel» led to an increase in recovery of nickel from 45,94 to 47,34 % and copper from 78,27 to 82,77 %.

Ionic liquids as novel quartz collectors: Insights from experiments and theory

Application of quaternary ammonium based ionic liquids (IL’s) as flotation collectors of quartz has been investigated. Effect of number of carbon atoms in the four identical alkyl chains of the IL’s has been studied. The adsorption behaviour of the IL’s on the quartz surface is ascertained through FTIR, XPS and molecular modelling. The FTIR peak at 2900cm−1 indicates the adsorption of the IL’s onto the quartz surface, which is further substantiated by the appearance of the N (1S) peak in the X-ray photoelectron spectra (XPS). Curve splitting data of C (1S) suggests the maximum adsorption for the IL tetrahexylammonium iodide (THEX). Flotation results of pure quartz using ionic liquids are found to be better compared to the conventional collectors such as dodecylamine (DDA) or cetyltrimethylammonium bromide (CTAB). It is possible to float 92–100% quartz by using a THEX concentration of 4.8 × 10−5M. IL collectors are further applied in the flotation of a low grade banded hematite quartzite (BHQ) iron ore with ∼38% Fe. It is possible to achieve an iron concentrate of 63.6% Fe at 63.2% recovery by using THEX as the collector. Molecular simulations using the COMPASS forcefield explains the IL–quartz adsorption mechanism comprising of both electrostatic and van der Waals forces. Floatability of quartz has been correlated with the surface coverage and adsorption energy calculations. The IL’s used here are found to be better quartz collectors than the conventional ones as they show better collecting efficiency in lower dosages. Flotation using these IL’s does not require frothers which is an added advantage compared to the conventional collectors.

Selection of sulfhydryl collectors for flotation of sulfides of nonferrous metals from refractory ores of nonferrous metals

Methods of selection of selective collectors are analyzed. The procedure for calculating characteristics of absolute rigidity, absolute electronegativity, and reaction ability of compounds is presented. The correspondence between the results of theoretical calculations of the reaction ability of sulfhydryl collectors and experimental results of adsorption and flotation of monomineral fractions of chalcopyrite, galenite, and pyrite by sulfhydryl collectors is revealed. The prediction of the collecting activity based on calculations is complicated by the features of the chemical composition of natural sulfides, and the defectiveness of the surface associated with the genesis of ore minerals in the deposit is revealed. Dithiophosphates and thionocarbamates are isolated as main components of the selective compositions of collectors for the flotation of pyrite ores of nonferrous metals based on theoretical and experimental investigations. It is shown by a complex of adsorption investigations in conditions of nonfrothing flotation and analysis of the IR frustrated total internal reflection (ATR) spectra of concentrates of nonfrothing flotation that the nonoptimal ratio of components weakly active relative to pyrite leads to a considerable increase in pyrite floatability. The sorption of components of the sulfhydryl collector and pyrite floatability increase when the fraction of a nonionogenic collector in the composition is lower than 40–60%. The action mechanism, which determines the action selectivity of sulfhydryl collectors during the flotation of sulfides, is determined.

The Experimental Study and Mechanism Analysis on Flotation Separation of Tetradymite and Pyrite

The experimental results of flotation of pure tetradymite and pyrite show that HL-1 is an efficient collector for tetradymite flotation. Comparing to the butyl xanthate, HL-1 has stronger collector ability and higher selectivity. It solves the common problem of the separation of tetradymite and pyrite. The difference of adsorption quantity is consistent with results of the single mineral flotation test. Through the measurements of adsorption, zeta-potential, and FTIR spectral analysis, the flotation mechanism of tetradymite with HL-1 has been discussed. It is concluded that the adsorption of HL-1 on tetradymite surface is chemical adsorption through the dithiocarbamate group of the collector chelating the Bi (III) of tetradymite to form metal complex.

INVESTIGATIONS OF GOLD BEARING ORES BENEFICATION

There were quoted results of sulphide flotation with regard to ores of Natalka deposit. There was showed a possibility of production from ore contended 2 g/t of Au concentrate with gold content from 40 to 95 g/t at release of it over the range from 30 to 5 %. Precious metal recovery in such a case is 90–35 %. Sorption leaching of received concentrate by virtue CIL method allows recovers from it from 87,1 to 96,4 % of gold that is equivalent to total recovery in the range of 75,2–83,2 %.

Selective chalcopyrite flotation from pyrite with glycerine-xanthate as depressant

Micro-flotation tests, adsorption, electrokinetic and FTIR measurements were carried out in order to investigate the selective depression mechanism of sodium glycerine-xanthate (SGX) on pyrite in chalcopyrite flotation. The flotation results showed a large difference in chalcopyrite (>85%) and pyrite (<30%) recovery as stirred pulp-mixing with SGX before the addition of collector sodium butyl xanthate (SBX), at the range of pH 7–10. A much stronger adsorption of SGX on pyrite than chalcopyrite was dramatically revealed by zeta potential measurements, which can explain the better floatability of chalcopyrite than pyrite. The adsorption of SBX onto pyrite was depressed intensely while that onto chalcopyrite was affected slightly when SGX was used as depressant, because of more stronger adsorption between SGX and SBX occurring onto the pyrite surfaces. The absorbed amount of SGX on chalcopyrite increases slightly, over the pH range from 3 to 12, while that on pyrite increases rapidly with the increased SGX concentration, which is consistent with the flotation results. FTIR reflection spectroscopic measurements further demonstrated the depression effect of pre-absorbed SGX on SBX adsorption, which is attributed to its hydrophilic hydroxyl groups.

Flotation and adsorption of muscovite using mixed cationic–nonionic surfactants as collector

The performance of the mixed dodecylamine chloride (DDA)/octanol (OCT) surfactants on muscovite flotation was investigated using flotation tests, and their adsorption mechanisms on muscovite and air/water interface were clarified using contact angle measurement, surface tension and molecular dynamics (MD) simulations. The flotation results indicate that the recovery of muscovite rapidly decreases when the pH increases in the presence of only DDA, whereas the recovery of muscovite is high (>77%) over a wide range of pH in the presence of the mixed DDA/OCT surfactants with a ratio of 2/1. Contact angle measurements further confirm that the mixture displays a stronger collecting power than DDA and is a superior collector for the muscovite flotation. The surface tensions of DDA, OCT and their mixture indicate that the mixture is more efficient than DDA at decreasing the air–water interfacial tension and exhibits much better surface activities. MD simulations show that the mixture interacts with the muscovite mainly through electrostatic attraction and hydrogen-bonding. DDA ion is dominant in the interaction between the mixture and muscovite. OCT molecules are co-adsorbed onto the muscovite through the hydrogen-bond interaction and hydrophobic association with DDA ions. Compared with DDA, a well-compacted monolayer is formed on the muscovite surface in the presence of mixed surfactants, indicating a much stronger hydrophobic character of muscovite.

Post-regrind selective depression of pyrite in pyritic copper–gold flotation using aeration and diethylenetriamine

The present study investigates the effect of aeration and diethylenetriamine (DETA) on the selective depression of pyrite in a porphyry copper–gold ore, after regrinding (at grind sizes, d80=38 and 8μm) with respect to Au recovery and grade using oxygen demand tests, flotation, QEMSCAN, X-ray spectroscopy (XPS) and EDTA extraction analysis. It was found that pyrite depression increases after aeration and with decreasing grind size. This was observed to be due to the markedly higher oxygen consumption rate of pyrite at the 8μm (kla=0.10min−1) than at the 38μm grind size (kla=0.02min−1). The addition of DETA improved pyrite depression (9% with aeration only versus 39% with aeration+DETA) at the 38μm grind size. Gold and copper flotation recovery followed pyrite recovery for the two grind sizes using XD5002 in the presence of air and DETA.The surface analysis (XPS and EDTA extraction) revealed that the significant pyrite depression at the 8μm grind size was due to increased amount of surface iron oxides, oxy-hydroxides (FeO/OH), sulphate species and increased liberation of mineral phases (QEMSCAN analysis), whilst the poorer pyrite depression at the 38μm grind size was due to insufficient liberation of mineral phases and the persistence of activating Cu on the pyrite surface. The addition of DETA increased pyrite depression at the coarser grind size due to a significant reduction in Cu(I)S and increased Cu(II)O species, correlating with the flotation results of pyrite under this test condition. Two-stage copper and pyrite flotation, followed by Au cleaning after regrinding to 38μm grind size, under high pH or aerated condition is proposed as the recommended route to optimise Au flotation.

Study on the flotation technology and adsorption mechanism of galena–jamesonite separation

In order to further separate the concentrate containing galena and jamesonite before undergoing hydrometallurgical process, flotation experiment was performed on the basis of mineralogical analysis. And the adsorption mechanisms of collector H on galena and jamesonite were also studied by FT-IR spectra analysis and molecular dynamics (MD) simulation. The flotation result shows that the efficient separation can be achieved with H as selective collector. Galena concentrated with Pb grade of 72.09% and Pb recovery of 50.96% was obtained, and jamesonite concentrated with Sb grade and recovery of 10.89% and 76.67% respectively was obtained as well. Infrared spectrum analysis indicates that collector H can adsorb on the surface of galena and react with Pb2+ to generate hydrophobic salt, while no evident adsorption phenomenon was observed on the surface of jamesonite. The MD simulation and calculation results demonstrate that adsorption energy of collector H on galena and jamesonite surface is −872.74kJ/mol and −500.538kJ/mol, respectively, which means collector H is easier to adsorb on the surface of galena than that of jamesonite.

A Study of the Optimal Model of the Flotation Kinetics of Copper Slag from Copper Mine BOR

Abstract In this study the effect of mixtures of copper slag and flotation tailings from copper mine Bor, Serbia on the flotation results of copper recovery and flotation kinetics parameters in a batch flotation cell has been investigated. By simultaneous adding old flotation tailings in the ball mill at the rate of 9%, it is possible to increase copper recovery for about 20%. These results are compared with obtained copper recovery of pure copper slag. The results of batch flotation test were fitted by MatLab software for modeling the first-order flotation kinetics in order to determine kinetics parameters and define an optimal model of the flotation kinetics. Six kinetic models are tested on the batch flotation copper recovery against flotation time. All models showed good correlation, however the modified Kelsall model provided the best fit.

Elimination of the adverse effect of cement filling on the flotation of a nickel ore

In China, most of the nickel sulphide deposit is spatially related to ultrabasic rocks and the cementation filling method is used in the process of mining. However, the cement filling from the mine back fill often gets into the ore and interferes with the pentlandite flotation. In this work, the effect of the cement filling on the flotation performance of a nickel ore was studied and ammonium sulphate was used to eliminate this adverse effect. The flotation result shows that the pentlandite recovery decreased from 87% to 65% with the increase of the content of cement filling from 0% to 8%. The addition of ammonium sulphate was shown to improve the flotation performance of pentlandite that depressed by cement filling. This result points out a problem often encounter in the flotation of a nickel sulphide ore and finds a solution to it.

Faecal egg counts from field experiment reveal density dependence in helminth fecundity: Strongyloides robustus infecting grey squirrels (Sciurus carolinensis).

Investigation of endo-macroparasite infections in living animals relies mostly on indirect methods aimed to detect parasite eggs in hosts' faeces. However, faecal flotation does not provide quantitative information on parasite loads, whereas faecal egg count (FEC) techniques may not give reliable estimates of parasite intensity, since egg production may be affected by density-dependent effects on helminth fecundity. We addressed this issue using Eastern grey squirrels (Sciurus carolinensis) and their gastrointestinal nematode Strongyloides robustus to assess the performance of coprological techniques and to investigate factors affecting parasite fecundity. We compared results of gut examination, flotation and McMaster FECs in 65 culled grey squirrels. Sensitivity and specificity of flotation were 81.2% (Confidence Interval, CI 54.3-95.9%) and 85.7% (CI 72.7-94.1%), respectively, resulting in low positive predictive values when infection prevalence is low. Individual parasite fecundity (no. of eggs/adult female worm) was negatively affected by S. robustus intensity, leading to a non-linear relationship between parasite load and eggs/gram of faeces (EPG). As a consequence, whereas flotation may be a valid method to perform the first screening of infection status, FECs are not a reliable method to estimate S. robustus intensity, since diverse values of EPG may correspond to the same number of parasites. Neither the amount of analysed faeces nor the season had any effect on EPG, indicating that the observed reduction in helminth fecundity is likely caused exclusively by density-dependent processes such as competition among worms or host immune response.

Flotation of all-wheel drive vehicle on snowy wild land

Experimental results of flotation of GAZ-66-40, KamAZ-4350, Ural-4320-30 and Ural-5323-20 all-wheel drive vehicles on snowy wild land are given. Comparative assessment of flotation is carried out on basic indicators such as specific drawbar force, specific force of resistance to towing of car, maximal speed of rectilinear uniform motion without towed load and minimal car turning radius without flotation loss.

Improved recovery of a low-grade refractory gold ore using flotation–preoxidation–cyanidation methods

In this work, different flotation–preoxidation–cyanidation methods are considered for treating a low-grade refractory gold ore. On the one hand, the results of selective flotation show that 22% and 31.1% of total Sb and As, respectively, remained in the final tailings and only about 28% of the total Au remained for further cyanidation processes. On the other hand, in bulk method of flotation the maximum Au recovery of 90.6% achieved after 60min of flotation at the grind size with K80 of 146micron. In addition, the bulk flotation method resulted in the concentrate with low concentrations of Sb and As elements. To improve the recovery of low-grade refractory gold ores, flotation should be followed by roasting, biological, or pressure oxidation processes so that the gold could be liberated prior to cyanidation processes. It is also found that the pressure oxidation pre-treatment of the concentrates prior to cyanidation may yield high gold recoveries of over than 83%. In these processes, recoveries are controlled by the temperature and the oxygen partial pressure in the solvent. However, by utilizing the bio-oxidation technique, the oxidation of sulfur to sulfate cannot be completed and, consequently, the gold recovery may be limited to only 72.2%.

Effects of particle size and chain length on flotation of quaternary ammonium salts onto kaolinite

Effects of particle size and chain length on flotation of quaternary ammonium salts (QAS) onto kaolinite have been investigated by flotation tests. Dodecyltrimethylammonium chloride (DTAC) and cetyltrimethylammonium chloride (CTAC) were used as collectors for kaolinite in different particle size fractions (0.075 ~ 0.01 mm, 0.045 ~ 0.075 mm, 0 ~ 0.045 mm). The anomalous flotation behavior of kaolinite have been further explained based on crystal structure considerations by adsorption tests and molecular dynamics (MD) simulation. The results show that the flotation recovery of kaolinite in all different particle size fractions decreases with an increase in pH. As the concentration of collectors increases, the flotation recovery increases. The longer the carbon chain of QAS is, the higher the recoveries of coarse kaolinite (0.075 ~ 0.01 mm and 0.045 ~ 0.075 mm) are. But the flotation recovery of the finest kaolinite (0 ~ 0.045 mm) decreases with chain lengths of QAS collectors increasing, which is consistent with the flotation results of unscreened kaolinite (0 ~ 0.075 mm). It is explained by the froth stability related to the residual concentration of QAS collector in mineral pulp. In lower residual concentration, the froth stability becomes worse. Within the range of flotation collector concentration, it’s easy of CTAC to be completely adsorbed by kaolinite in the particle size fraction (0–0.045 mm), which led to lower flotation recovery. Moreover, it is interesting that the coarser particle size of kaolinite is, the higher flotation recovery is. The anomalous flotation behavior of kaolinite is rationalized based on crystal structure considerations. The results of MD simulations show that the (001) kaolinite surface has the strongest interaction with DTAC, compared with the (001) face, (010) and (110) edges. On the other hand, when particle size of kaolinite is altered, the number of basal planes and edge planes is changed. It is observed that the finer kaolinite particles size become, the greater relative surface area of edges and the more the number of edges are. It means that fine kaolinite particles have more edges to adsorb fewer cationic colletors than that of coarse kaolinite particles, which is responsible for the poorer floatability of fine kaolinite.

The interaction of N-butoxypropyl-N′-ethoxycarbonylthiourea with sulfide minerals: Scanning electrochemical microscopy, diffuse reflectance infrared Fourier transform spectroscopy, and thermodynamics

The adsorption mechanism of N-butoxypropyl-N′-ethoxycarbonyl thiourea (BOPECTU) on chalcopyrite surfaces was investigated by thermodynamics, scanning electrochemical microscopy (SECM), and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The thermodynamic results demonstrated that the adsorption agreed well with the Langmuir or Freundlich isotherm and the adsorption parameters of thermodynamics were ΔG (303K)=−31.02kJmol−1, ΔS=10.92Jmol−1K−1 and ΔH=−27.71kJmol−1. It inferred the adsorption of BOPECTU on chalcopyrite was a spontaneously exothermic chemisorption process. The in situ SECM images indicated the adsorption of BOPECTU on chalcopyrite resulted in the decrease of the current response. DRIFT spectra exhibited that after BOPECTU treatment, the characteristic peaks of copper–BOPECTU complex appeared on chalcopyrite surfaces, while on pyrite or sphalerite surfaces, no new peaks appeared. UV–vis and FTIR spectra elucidated that BOPECTU showed more affinities to Cu2+ ions than to Zn2+, Fe3+ or Fe2+ ions, and might bond copper atoms with its sulfur and nitrogen atoms. The results of flotation and adsorption experiments further demonstrated BOPECTU owned stronger collecting ability to chalcopyrite than to sphalerite or pyrite.

Flotation of ultra-fine rare-earth minerals with selective flocculant PDHA

The flocculating performance of 1,4-benzoyl hydroxamic acid (PDHA) on ultra-fine bastnasite was studied by individual and artificially mixed minerals flotation tests, and its optimum flocculation conditions including agitation speed, conditioning period and dosage were confirmed as well. Flotation results indicate that PDHA enhances the recovery of ultra-fine rare earth minerals, and it is possible that PDHA could be used as an effective flocculant in the treatment of low grade and finely disseminated rare earth ore.

Smithsonite Flotation from Zinc Oxide Ore using Alkyl Amine Acetate Collectors

Flotation of smithsonite from tailing coming from a cerussite flotation circuit was investigated using Armac C and Armac T as alkyl amine acetate collectors. The results showed that the dosage of Na2S, collector type and dosage, collector's mixture ratio, and desliming are the main affecting parameters on the Zn grade and recovery of smithsonite flotation concentrate. The contact angle measurement on smithsonite and calcite minerals indicated that Armac T acts more selectively than Armac C and enhances the Zn grade of the concentrate. At the mixture ratio of Armac C:Armac T, 1:6, the collectors' consumption are decreased significantly and an optimal concentrate with 94.4% recovery and 42.3% Zn grade is obtained without any gangue depressant reagents. Nevertheless, using NaOH as a pH regulator, the dosage of Na2S is decreased significantly but the flotation results are affected negatively. The recovery of Zn in the concentrate is more sensitive to the slime than Zn grade. The Zn minerals lost in the tailing are mostly in the form of very fine disseminated particles. About 11% of smithsonite with particle sizes finer than 10 µm is lost in the slime. Overall Zn flotation recovery is estimated to be about 84%.