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1

Evaluation of flotation reagents by normalization procedures

Drzymala J.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 1

182--192

EN

Froth flotation is a dynamic multiphase process in which particulate matter is separated with the help of chemical reagents by gas bubbles immersed in water. The original flotation results are usually presented in the form of kinetic curves relating recovered particulate matter mass (yield ) or mass of a selected component (recovery ), both shortly denoted as y, versus process time t at different concentrations c (g/dm3) of the applied reagents. The kinetic curves can be modified into three: incentive (maximum yield or recovery ymax vs c), limits (ymax vs kinetic constant k or specific rate) and half-life of flotation (t1/2 vs c) curves. The original and modified curves can be normalized by taking into account either an external parameter such as molecular mass (MW), critical coalesce concentration (CCC), critical concentration at the minimum bubble velocity (CMV), dynamic foaming index (DFI), and many other parameters or an internal parameter such as time, concentration needed to achieve certain yield, recovery (y) or kinetic constant. Normalization leads to new flotation curves and provides additional useful information about flotation performance. Normalization can be fully effective, partial or ineffective. Normalization of the original flotation kinetic curves usually is ineffective. Also, normalization of the incentive curve with external parameters such as frother molecular mass, which changes reagent concentration from c (g/dm3) to C (mol/dm3), is also ineffective. Partially effective are normalizations with other external parameters such as CCC and CMV, usually within the same class of regents, for instance alcohols. Only DFI seems to be a universal external normalization parameter for flotation results because it provides fully effective normalization and thus predicts the flotation results. Limited data on DFI restrict a full verification of this hypothesis. Normalization of the modified flotation curves with internal parameters such as k50 (value of 1st order kinetic constant when recovery or yield is 50% after a given flotation time), Ct1/2 (frother concentration in mol/dm3 at which the flotation half-life has an arbitrarily chosen value) and cy75 (frother concentration in g/dm3 at which recovery or yield is 75% after a given flotation time) is a good base for practical classification of flotation reagents.

2

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.

3

Kinetic separation curves based on process rate considerations

Drzymala J., Ratajczak T., Kowalczuk P. B.

Physicochemical Problems of Mineral Processing

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2017

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Vol. 53, iss. 2

983--995

EN

There are many graphical representations of separation results involving time as a crucial parameter determining the kinetics of a process. The graphical representations of results of separation are usually in the form of 2D plots relating two parameters which one of them is time. Time can also be utilized as a complex parameter such as a process rate. The plots involving time are called kinetic curves. Theoretically, the number of kinetic curves is infinite. The basic process kinetic curves, relating either yield (or recovery) and time can be modified to obtain numerous local and global efficiency curves. The global efficiency kinetic curves provide characteristic constants which do not change with the time and yield of a process. In this paper the local and global efficiency plots were created using experimental data which followed the so-called first order kinetics. It was shown that the integral 1st order kinetic equation provided the kinetic constant k which was numerically identical with the 1st order specific rate v, while their units were different (k, 1/min; v, %/(%·min). The global efficiency parameters plotted versus the maximum yield provided another type of plot, which can be called the limits kinetic curve. The limits kinetic curves are very useful for characterizing, quantification and classification of separation systems. The limits kinetic curves can be normalized providing one universal curve with a characteristic point, for instance, v50 indicating the specific rate (or kinetic) constant at the maximum recovery equal to 50%. The mathematical equation of the normalized limits kinetic curve was given in the paper.

4

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.

5

Some remarks on attachment of a gas bubble to another phase both immersed in water

Kowalczuk P. B., Drzymala J.

Physicochemical Problems of Mineral Processing

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2016

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Vol. 52, iss. 1

147--154

EN

In this paper the importance of definition of hydrophobicity and aquaoleophilicity in terms of contact angle as well as the properties of water films in flotation and oil agglomeration were briefly presented. It was shown that the hysteresis of contact angle for a considered system depends on the way of measurement and geometry of the system due to the presence of other that excess pressure and capillary forces and buffering properties of the capillary force. It was suggested that, the measured advancing and receding contact angles should be, when possible, recalculated into the Young (rest, equilibrium) contact angle. It was discussed that quartz is not a good model of hydrophilic surface because its contact angle with a gas phase in water is not zero and that a spontaneous attachment between highly hydrophobic materials such as hydrocarbons and Teflon in dynamic system, such as flotation, does not occur.

6

Professor Janusz Kazimierz Girczys, Ph.D., D.Sc. a tribute on his 80th birthday

Laskowski J., Drzymala J.

Physicochemical Problems of Mineral Processing

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2016

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Vol. 52, iss. 1

510--517

7

Influence of frother type and dose on collectorless flotation of copper-bearing shale in a flotation column

Kowalczuk P. B., Mroczko D., Drzymala J.

Physicochemical Problems of Mineral Processing

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2015

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Vol. 51, iss. 2

547--558

EN

In this paper the influence of nonionic (methyl isobutyl carbinol, tri(ethylene glycol) monobutyl ether) and cationic (hexylamine) frothers on flotation of copper-bearing shale in a flotation column was investigated. It was shown that naturally hydrophobic shale did not float in pure water but it floated in the presence of the investigated frothers. The real contact angle of shale, measured by the sessile drop method, was equal to about 40°, while its effective contact angle was zero when shale was floated in a flotation column in pure water. The investigated surfactants increased the effective hydrophobicity of shale from zero to 16±1, 22±1 and 33±2° for coarse, medium and fine particles, respectively. The calculations of the effective contact angle were based on a simplified probabilistic model of flotation.

8

In search of an efficient frother for pre-flotation of carbonaceous shale from the kupferschiefer stratiform copper ore

Kowalczuk P. B., Buluc B., Sahbaz O., Drzymala J.

Physicochemical Problems of Mineral Processing

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2014

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Vol. 50, iss. 2

835--840

EN

This papers shows that frothers such as aliphatic alcohols (CnH2n+1OH), poly(propylene glycols) (HO(C3H6O)mH), poly(propylene glycol) alkyl ethers (CnH2n+1O(C3H6O)mH) and poly(ethylene glycol) alkyl ethers (CnH2n+1O(C2H4O)mH), can be used for collectorless flotation of a sample of carbonaceous copper shale manually separated from the Kupferschiefer stratiform copper ore. It was shown that flotation is influenced by the type and dose of frothers. The best flotation results were obtained with tri(propylene glycol) butyl ether C4P3, tri(propylene glycol) propyl ether C3P3 and tri(propylene glycol) P3. For these frothers, the yield vs. frother dose relationship was in the form of convex curves indicating that carbonaceous copper shale can float at relatively low dosages of the frother. It means that these frothers can be used for pre-flotation of carbonaceous matter from the investigated copper ore. Other frothers formed concave yield–frother dose relationships and were less effective.

9

Interrelation of the fuerstenau upgrading curve parameters with kinetics of separation

Bakalarz A., Drzymala J.

Physicochemical Problems of Mineral Processing

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2013

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Vol. 49, iss. 2

443--451

EN

It was shown in the paper that kinetic equations relating recoveries of two components in separation products and time, when combined together to eliminate the time parameter, provide mathematical equations which relate recoveries of the two considered components in concentrate. The obtained one-adjustable-parameter type equations are very useful for approximation of the separation results plotted as the so-called Fuerstenau upgrading curves. Most empirical mathematical formulas presently used for the Fuerstenau plots were derived using various kinetic equations while some are still awaiting for their kinetic derivation.

10

Flotation after a direct contact of flotation reagents with carbonate particles. Part 1, Model investigations

Ahmed H. A. M., Aljuhani M. S., Drzymala J.

Physicochemical Problems of Mineral Processing

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2013

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Vol. 49, iss. 2

713--723

EN

Carbonate fluorapatite (francolite), calcite and dolomite separately, as well as their model mixtures, were subjected to flotation after conditioning the particles with microemulsion consisting of 20% of Custafloat AR27 (collector, blend of fatty acid soaps and sulfates), 55% fuel oil #5 and 25% water at 70% solids density and subsequent pulp dilution with water to 25% solids. The best separation of carbonate fluorapatite from calcite and dolomite occurred at pH 8.5 and microemulsion dose between 0.9 and 1.5 kg/Mg, 1.5 min conditioning time and 2 minutes of flotation time. The obtained flotation concentrates using 1.5 kg/Mg of collector contained 84% carbonate fluorapatite (34% P2O5) with 84% recovery. The 84/84 separation efficiency in terms of grade-recovery indices points to promising results which can be obtained for real phosphate ores.