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1

Mineralogical characteristic and beneficiation evaluation of rare earth carbonate wall rock

Gao Chunqing, Yan Guoying, Wang Hailiang, Luo Hongzhen, Zhang Lin, Yang Hanxu, Xu Jian

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 1

art. no. 161300

EN

In order to rationalize the development and utilization of the wall rock discarded during rare earth mining, chemical analysis, inductively coupled plasma-atomic emission spectroscopy, X-ray diffraction analysis, artificial panning, optical microscope analysis, mineral liberation analysis and energy-dispersive spectroscopy were used to study the process mineralogy of the wall rock. The results show that the main useful elements in the rare earth wall rock were iron, light rare earth elements, fluorine and niobium. Iron was mainly occurrence as magnetic iron in magnetite, rare earth elements in bastnaesite and monazite, fluorine as a independent mineral in fluorite and niobium in columbite. The main useful minerals were finely disseminated, with magnetite (48.16%), bastnaesite (49.04%), monazite (42.18%), fluorite (39.30%) and columbite (63.26%) distributed in -0.030 mm particle size. The useful minerals were evaluated separately for beneficiation based on the process mineralogical characteristics of the rare earth wall rock, and the results showed that magnetite, rare earth and fluorite resources could be effectively recovered using magnetic separation, flotation, gravity concentration and leaching enrichment methods. The sequential recovery of iron, rare earth, fluorine and niobium elements produces iron concentrate (65.40% TFe at recovery of 38.03%), rare earth concentrate (50.66% REE at recovery of 62.73%), fluorite concentrate (95.23% CaF2 at recovery of 40.34%) and niobium iron ore concentrate (1.63% Nb2O5 at recovery of 5.56%). This study provides recommendations for the rational development and utilization of rare earth wall rock and provides reasonable levels of recovery predictions.

2

The behaviour of tannic acid adsorption on fluorite surface: isotherm, kinetic and thermodynamic studies

Tangarfa Mariam, Semlali Aouragh Hassan Naoul

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 1

77--87

EN

Fluorite is an important mineral to produce hydrofluoric acid. As fluorite resources contain calcite as a gangue mineral, the separation between these two calcium containing minerals is difficult. Tannic acid is the most commonly used reagent as a depressant to separate fluorite from calcite by flotation. To enhance this separation, it is so primordial to understand tannic acid physicochemical reactivity via these minerals. Therefore, the aim of this work is to investigate the mechanism of tannic acid adsorption on the fluorite surface by experimental study using isotherm, kinetic and thermodynamic. Adsorption isotherm modelling results showed that the adsorption process is well described by Sips model. On the other hand, the kinetic and thermodynamic require firstly the adsorption study as a function of three main reactional parameters including initial tannic acid concentration, solution pH and temperature. This study showed that acidic pH as well as initial tannic acid concentration increase and temperature decrease promote the studied adsorption. These finding were then exploited to determine the adsorption mechanism by pseudo n order kinetic model adjustment to experimental kinetic data using nonlinear regression method. Obtained high correlation coefficient and low mean absolute error at 95 % confidence level showed good agreement of experimental kinetic data with the tested model. These results revealed that the mechanism of tannic acid adsorption onto fluorite was attributed to a chemical reaction. In addition, the thermodynamic study showed that the studied adsorption process was exothermic.

3

Influence and mechanism of Zn2+ on fluorite/calcite in sodium hexametaphosphate flotation system

Ruitao Liu, Dan Liu, Ruofan Sun, Daqian Wang, Wenkang Zhang, Yuebing Liu, Shuming Wen

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 6

art. no. 151676

EN

Fluorite and calcite have similar surface properties and natural floatability, so their flotation separation has always been a problem faced by the beneficiation industry. The key to flotation separation is the choice of depressants. Sodium hexametaphosphate (SHMP) has a good effect on fluorite calcite selective inhibition. In this paper, the effects of Zn2+ on the selective inhibition of SHMP in the flotation process of fluorite and calcite were studied through single mineral and artificial mixed mineral flotation experiments. Solution chemical calculation, X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared spectroscopy (FT-IR) and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) analyses investigated the mechanism of action of Zn2+, which had the most significant negative effect on the selective inhibition of SHMP. The results show that the main components of SHMP inhibiting minerals are HPO42- and H2PO4-, which can react with Ca active sites on the mineral surface to form hydrophilic Ca(H22PO4)2 and CaHPO4, while Zn2+ The presence of HPO42- in solution resulted in the formation of stable ZnHPO4 complexes, thereby weakening the inhibitory effect of SHMP on minerals.

4

Effect and mechanism of depressant CK102 on flotation separation of fluorite and dolomite

Li Zhengyao, Wang Xuewen, Xu Chengyan, Sun Tichang, Liu Weiran, Wei Jinzhi

Physicochemical Problems of Mineral Processing

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2022

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Vol. 58, iss. 3

art. no. 145796

EN

For a low grade dolomite type fluorite ore in the Hebei province, it was observed that the depressant CK102, a mixture of sulfuric acid, sodium silicate and aluminum sulfate, can effectively inhibit the gangue mineral dolomite in the flotation of fluorite. However, the inhibition mechanism of the depressant is still unclear. In this paper, the flotation separation performance and underlying mechanism of CK102 inhibiting dolomite were investigated through mineral flotation tests, adsorption measurements, infrared spectroscopy, and X-ray photoelectron spectroscopy (XPS). The flotation results showed that the inhibition effect of CK102 on dolomite flotation was much more remarkable than that of fluorite flotation under optimum conditions. Adsorption measurements revealed that there was competitive adsorption between the depressant and collector and that the adsorption of the depressant CK102 prevented the collector modified sodium oleate from adsorbing onto the surface of minerals. The FT-IR and XPS results showed that the co-oxygen cross-linked component of the depressant CK102 chemisorbed on the surface of dolomite; the CaSiO3 precipitation was generated from the reaction of CK102 with Ca2+ groups on the surface of the dolomite; Al2MgO8Si2 precipitation was also generated from Mg2+ reacting with the sodium silicate and aluminum sulfate of CK102. The above adsorptions and reactions enhanced the hydrophilicity of the dolomite surface and the dolomite was effectively depressed.

5

Kozłowski Andrzej, Matyszczak Witold

Acta Geologica Polonica

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2022

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Vol. 72, no. 1

9--31

EN

Fluorite mineralization was studied in the Variscan granitoid Karkonosze pluton in the northern part of the Bohemian massif (Lower Silesia, Poland). Fluid inclusions in fluorite and quartz were investigated by the following methods: heating and freezing on an immersion microscope stage, spectrophotometric and electron probe analysis, calcination and water leachate. The parent fluids of fluorite were of the Na-Ca-Cl type with a low CO₂ content. The fluoride ions had sources in the pluton and in its host rocks. Fluid inclusion observations provide evidence of various post-formation alteration. such as refilling, partition, cracking, migration, expulsion or vacuole modification from irregular to cubic habit. A final model of fluorite origin and parent fluid evolution is presented.

6

Homogenization phenomena of surface components of fluorite and calcite

Sun Ruofan, Liu Dan, Zhang Benyue, Lai Hao, Wen Shuming

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 1

250--258

EN

The flotation separation of fluorite and calcite poses one of the most difficult problems in the mineral processing industry. In particular, the surface homogenization of fluorite and calcite worsens the result of fluorite flotation. In this paper, time of flight secondary ion mass spectrometry and principal component analysis are used to study the surface homogenization of fluorite and calcite during grinding and in solution using X-ray photoelectron spectroscopy, infrared spectroscopy, and solution chemical calculations. The results show that the surface composition of calcite converts to fluorite after mixed grinding and that the surface composition of fluorite also converts to calcite in clarified calcite solution.

7

Effects of Ca2+ and SO4 2- ions on fluorite flotation

Xun Luobing, Hu Jiacheng, Shi Qing, Zhang Guofan

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 2

95--104

EN

The effects of Ca2+ and SO4 2- on the flotation behaviour of fluorite with sodium oleate as a collector and the underlying mechanism by which these effects were investigated via micro-flotation experiments, solution chemistry calculations, and X-ray photoelectron spectroscopy. The results indicated that the addition of SO4 2- and Ca2+ inhibited fluorite flotation and the inhibition effect was increased by the addition of pH. This was mainly due to the increase of the sulphate-containing components in the solution and the adsorption of SO4 2- on the surface of fluorite. With the increase of pH, the alkalinity of the solution increases, OH- and more SO4 2- are further adsorbed on the fluorite surface, thereby reducing the recovery of fluorite flotation.

8

Effect of grinding media on the flotation behavior of fluorite using sodium oleate as a collector

Yao Wei, Li Maolin, Zhang Ming, Qian Gongming, Cui Rui, Ning Jiangfeng

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 3

556--565

EN

Grinding, an essential procedure before flotation, to some extent, determines the flotation behavior of minerals. In this study, the effect of grinding media on the flotation behavior of fluorite using sodium oleate (NaOl) as a collector was investigated via micro-flotation experiments, zeta potential measurements, scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) analyses. The results indicated that, compared with the fluorite particles ground by ceramic media, the ones ground by cast iron media adsorbed less NaOl, resulting in lower flotation recovery. The lower flotation recovery of fluorite particles ground by cast iron media resulted from the coating of the hydrophilic Fe precipitates generated in the grinding, including Fe(0), Fe(OH)2, and Fe(OH)3on their surfaces. These Fe precipitates may cover the Ca active sites and increase the hydration membrane which can inhibit the further NaOl adsorption. This research reveals the effect of grinding media on the flotation behavior of fluorite and guides for media selection in disposing of fluorite ore.

9

The effect of polyacrylic acid on the surface properties of calcite and fluorite aiming at their selective flotation

Zhang C., Gao Z., Hu Y., Sun W., Tang H., Yin Z., He J., Guan Q., Zhu Y.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 3

868--877

EN

In this study, the polyacrylic acid (PAA) was studied as a selective depressant for calcite in the selective flotation of fluorite and calcite, and the implications of this process for the separation of fluorite ore were studied using micro-flotation tests, and the results were analyzed with Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analyses. The flotation tests indicated that the preferential adsorption of PAA onto calcite rather than sodium oleate (NaOl) could selectively depress the flotation of calcite, allowing its separation from fluorite at pH 7. The zeta potential of calcite became more negative with the addition of PAA rather than with NaOl. However, the characteristic features of PAA adsorption were not observed for fluorite, suggesting that NaOl preferentially adsorbed on the surface of fluorite, or that PAA could be replaced by NaOl on the fluorite surface. FT-IR and XPS analysis were utilized to obtain a better understanding of the mechanism by which PAA was more strongly adsorbed on the calcite surface than NaOl. This was revealed to occur through chemical bonding between the carboxyl group of PAA and the hydroxyl groups of the Ca species on the calcite surface, modifying the structure of the adsorbed layer. A possible adsorption mechanism, along with a postulated adsorption mode for the surface interaction between PAA and calcite, is proposed.

10

Effect of modified starch on separation of fluorite from barite using sodium oleate

Chen Z., Ren Z., Gao H., Qian Y., Zheng R.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 2

228--237

EN

In this study, a modified starch was utilized to selectively separate barite from fluorite. The results of flotation tests showed that highly selective separation of fluorite from barite was obtained when 250 mg/dm3 of modified starch and 13.16×10−5 mol/dm3 sodium oleate was used in neutral solutions. FTIR spectra results showed that the modified starch can adsorb on the fluorite and barite surfaces. Zeta potential analyses indicated that the modified starch had little effect on adsorption of sodium oleate on the fluorite surface, although it interfered with the adsorption of sodium oleate on the barite surface. Contact angle measurements results corresponded well with the flotation results.

11

Water contact angle on corresponding surfaces of freshly fractured fluorite, calcite and mica

Kowalczuk P. B., Akkaya C., Ergun M., Janicki M., Sahbaz O., Drzymala J.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 1

192--201

EN

Advancing and receding contact angles of water with corresponding surfaces of freshly fractured calcite, fluorite and mica were measured. The corresponding surfaces were obtained by mechanical splitting of a small lump of each mineral into two pieces. Theoretical considerations revealed that depending on the mineral cleaving plane, surfaces created by splitting into halves can be either identical or entirely different as far as their surface chemical composition is concerned. It was experimentally established that receding and advancing contact angles measured on the corresponding surfaces of fluorite, calcite and mica were identical for the sessile drop method. When the contact angle was measured by the captive bubble approach, there were small differences in the contact angles measured on the corresponding surfaces of fluorite. It was most probably due to surface irregularities and roughness, and therefore different times needed to rupture the liquid film between the bubble and solid surface.

12

Effects of colloidal montmorillonite particles on froth flotation of graphite, galena and fluorite

Chen T., Zhao Y., Li H., Song S.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 2

699--713

EN

The effect of colloidal montmorillonite (MMT) on froth flotation of graphite, galena and fluorite was investigated in this work. The results showed that the presence of sufficient amount of colloidal MMT particles in the mineral slurry would be detrimental of flotation by reducing the recovery of minerals. This observation was attributed to slime coating of MMT on the coarse valuable mineral particles and entrainment of MMT particles in the froth product together with water in the triangle froth zones. The former would reduce the recovery of the valuable minerals because of hydrophilic MMT coating. The latter would decrease the concentrate grade. The degree of slime coating depended on slurry pH, while the degree of entrainment was closely related to water recovery. It was also found that slime coating was a dominant factor in mineral flotation in acidic pH regions in the presence of colloidal MMT particles.

13

Structure and surface energy of both fluorite halves after cleaving along selected crystallographic planes

Janicki M. J., Drzymala J., Kowalczuk P. B.

Physicochemical Problems of Mineral Processing

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2016

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Vol. 52, iss. 1

451--458

EN

The density functional theory, supported with a commercial software, was used to compute the geometry and surface energy of fluorite cleaved along the (111), (110) and (100) planes. In the case of cleaving a piece of fluorite along the (111) plane the two newly created surfaces are identical consisting of fluorite ions with the surface energy equal to 0.384 J/m2. Cleaving fluorite along the (110) plane also provides identical halves and, both contain one Ca ion next to two F ions, with the surface energy equal to 0.723 J/m2. When cleaving takes place along the (100) plane, it creates two corresponding halves with different surface structures. One half, having only surface Ca ions (100Ca) has the surface energy equal to 0.866 J/m2, while the surface energy of the second half, having only F surface ions (100F), is 0.458 J/m2. Different structures and energies of the corresponding fluorite surfaces, that is (100Ca) and (100F) planes, should have an impact on their chemical properties, including hydrophobicity expressed by contact angle. The calculations performed in the paper also showed that reorganization of fluorite surfaces after cleaving was insignificant for all of the investigated planes.

14

Selective Flotation of Barite and Associated Minerals: A Comparative Study

Kecir M., Kecir A.

Inżynieria Mineralna

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2015

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R. 16, nr 2

117--124

EN

In the present socio-economical difficult context and with the oil prices fall, Algeria aims to develop its economy. For this purpose, it has to research, work and valorize not only its hydrocarbons resources, but also mineral ones, among which barite and fluorite, two industrial minerals of great importance. Because Algeria is a producer of gas and oil and a member of the OPEC, it needs important quantities of barite. This mineral plays a leading role in the oil industry, where it’s a major ingredient of the drilling muds. As for fluorite, it is essentially used as flux in metallurgy, especially as the country has a huge iron deposit in Gara Djebilet, with a potential of 2,5 billions tons, that will support the steel platform of Algeria. Particularly interesting areas with reserves of almost 300 000 tonnes of fluorite have been highlighted in the Hoggar in Sahara. In order to answer the requirements of the mentioned uses, barite and fluorite ores have to undergo an appropriate processing. The method here applied is flotation, during which different reagents, both anionic and cationic, have been tested in order to choose those who give the best results. The aim of our study is, in a first step, a systematic flotation behaviour of barite and associated minerals, during which various collectors, combined with modifiers have been tested. Then, an artificial mixtures flotation was carried out and all the optimal conditions of flotation were applied to barite and fluorite-barite ores. Definitive choice of optimal flotation requirements focused on Petronate L (1000 g/t ; pH 6.5) for barite flotation and on Flotbel R171A (100 g/t; pH 9) for fluorite, combined with potassium dichromate as depressing agent for quartz and barite. The final flotation treatment has led to the obtention of a barite concentrate with a 93,4% BaSO4 grade and a fluorite concentrate with 93,6% CaF2,both answering the users’ requirements.

PL

W obecnej trudnej sytuacji socjoekonomicznej, w połączeniu ze spadkiem ceny ropy, Algieria jest nastawiona na rozwój ekonomiczny. W tym celu należy przeprowadzić badania, prace i waloryzację zasobów nie tylko surowców węglowodorowych, lecz również mineralnych, do których można zaliczyć baryt i fluoryt – dwa istotne minerały przemysłowe. Z racji tego, że Algieria prowadzi wydobycie gazu i ropy oraz jest członkiem OPEC, ma wysokie zapotrzebowanie na baryt. Minerał ten ma kluczowe znaczenie w przemyśle naftowym jako główny składnik iłowych płuczek wiertniczych. Fluoryt jest używany jako substancja zmiękczająca w metalurgii. Jest to istotne z powodu dużego złoża znajdującego się w tym kraju w GaraDjebilet, której zasoby sięgają 2,5 miliardy ton. Szczególnie interesujące tereny z zasobami fluorytu dochodzącymi do 300 000 ton mieszczą się w Hoggar na Saharze. W odpowiedzi na zapotrzebowanie przemysłu rudy barytu i fluorytu muszą być poddawane wzbogacaniu. Zastosowano flotację, podczas której badano odczynniki, zarówno anionowe jak i kationowe. Celem badań, w pierwszym etapie, było określenie wyników (efektów) flotacji barytu i minerałów towarzyszących, podczas której testowano różne kolektory wraz z ich modyfikatorami. Następnie przeprowadzono flotację sztucznych mieszanek oraz określono optymalne warunki flotacji rud barytu i fluorytu. Ostateczny wybór najlepszych parametrów technologicznych flotacji, został oparty na odczynniku zbierającym Petronate L (1000 g/t; pH=6,5) dla flotacji barytu oraz na Flotbel R171A (100 g/t; pH=9) dla fluorytu, w połączeniu z dichromianem potasu, jako czynnika depresyjnego dla kwarcu i barytu. Optymalny proces flotacji doprowadził do otrzymania koncentratu barytu z BaS04 na poziomie 93,4% i koncentratu fluorytu zawierającego 93,6% CaF2. Oba spełniają wymogi użytkowników.

15

Luminescence properties of Ce3+ and Eu2+ in fluorites and apatites

Bodył S.

Mineralogia

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2009

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Vol. 40, iss. 1/4

85--94

EN

Natural samples of fluorite and apatite from granites, pegmatites, carbonatites and andesitic tuffs were investigated by steady-time spectroscopy to characterize the luminescence properties of Ce3+ and Eu2+. The luminescence of Ce3+ has been clearly seen in fluorite as 320 and 337 or 343 nm bands. In apatites, two distinct bands for two different Ca crystal sites were obtained: 340–380 nm for Ca(1) and 420–450 nm for Ca(2). The luminescence spectra of Eu2+ in the fluorite crystals were measured even at for low concentration of this element (0.11 ppm). For Ce3+, it has been showed that the crystal field strength depends more on the nature of the ligand than on the Me-ligand distances.

16

Natural hydrophobicity and flotation ff fluorite

Zawala J., Drzymała J., Małysa K.

Physicochemical Problems of Mineral Processing

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2007

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Vol. 41

5-11

EN

The free ascending bubble–fluorite surface collision test showed that the three phase contact (TPC) was formed and time of the TPC formation was strongly affected by the roughness of the fluorite surface. The time of the TPC formation varied by an order of magnitude, from ca. 20 to 200ms, depending on the fluorite origin and surface roughness. The fact that the TPC was formed shows that fluorite can be considered as a naturally hydrophobic material. The contact angle formed by the bubble attached to fluorite plate was found to be 40 st. in comparison to 10-25 st. measured by flotometry and 55 st. by sessile drop. Thus, the macroscopic contact angle of fluorite depends on the method of measurement as well as its origin and color since colorless fluorites float better. Hydrophobicity of fluorite and the time of the three phase contact formation influence its flotation. The best flotation is observed in Hallimond tubes while flotation is significantly reduced or absent in laboratory flotation machines. This is very likely a result of relatively long time of the TPC formation and/or low hydrophobicity of fluorite, which is not enough to withstand the detachment force during enhanced hydrodynamics of larger flotation devices.

PL

Badania kolizji swobodnie wznoszącego się pęcherzyka z powierzchnią mineralną zanurzoną w wodze wykazały, że czas tworzenia się kontaktu trójfazowego silnie zależy od chropowatości powierzchni fluorytu. W zależności od chropowatości powierzchni fluorytu, czas kontaktu wynosił od 20 do 200ms. Tworzenie się kontaktu trójfazowego świadczy o naturalnej hydrofobowości fluorytu. Kąt zwilżania tworzony pomiędzy pęcherzykiem powietrza a płaska płytka fluorytową zanurzoną w wodzie wynosił 40 st. w porównaniu do wartości 10-15 st. uzyskanych metodą fotometryczną i 55 st. uzyskaną metodą siedzącej kropli. Zatem makroskopowy kąt zwilżania dla fluorytu zależy od metody pomiaru oraz pochodzenia próbki, a nawet jego koloru, gdyż barwne odmiany flotują lepiej. Hydrofobowość fluorytu oraz czas tworzenia się kontaktu trójfazowego wpływają na flotację. Najlepszą flotację obserwuje się w celce Hallimond, podczas gdy flotacja w mechanicznej maszynce laboratoryjnej jest znacząco zredukowana z powodu względnie długiego czasu tworzenia się kontaktu trójfazowego i/lub słabą hydrofobowością fluorytu, który nie wytrzymuje zwiększonych sił odrywania występujących w większych maszynach flotacyjnych.