Anionic collectors

By using an anionic collector and external reflux in a combined (enriching and stripping) column of 3.8-cm (1.5-in) diameter with a feed rate of 1.63 ni/n [40 gal/(h ft )] based on column cross section, D/F was reduced to 0.00027 with C JCp for Sr below 0.001 [Shou-feld and Kibbey, Nucl. AppL, 3, 353 (1967)]. Reports of the adsubble separation of 29 heavy metals, radioactive and otheiwise, have been tabulated [Lemlich, The Adsorptive Bubble Separation Techniques, in Sabadell (ed.), Froc. Conf. Traces Heavy Met. Water, 211-223, Princeton University, 1973, EPA 902/9-74-001, U.S. EPA, Reg. 11, 1974). Some separation of N from by foam fractionation has been reported [Hitchcock, Ph.D. dissertation. University of Missouri, RoUa, 1982]. 

By using an anionic collector and external reflux in a combined (enriching and stripping) column of 3.8-cm (1.5-in) diameter with a feed rate of 1.63 m/h [40 gaP(h fU)] based on column cross section,... 

S. K. Mishra, Anionic Collectors in Non-sulfide Mineral Flotation, in Reagents in Mineral Technology, P. Somasundaram and B. K. Moudgil, eds., vol. 27, Surfactant Science Series, Mercel Dekker Inc., p. 195, New York, 1988. 

Figure 19.3 illustrates the floatability of pure malachite with different amines. It should be pointed out that there are several varieties of malachite, Cu4(P04)2(0H)4-0H. Pseudomalachite is difficult to float, and it is well known that pseudo-malachite can be floated with anionic collectors, but responds poorly to the sulphidization method. 

Research work carried out at the Mechanobre Institute in Russia involved the evaluation of cationic and anionic collectors [8], The anionic collectors examined included sodium oleate and sodium alkyl sulphate. The results obtained indicated that with the use of sodium oleate, both zircon and pyrochlore can be floated with good recoveries (Figure 22.3). 

Monazite is readily floatable using cationic collectors such as oleic acid and sodium oleate in the pH region of 7-11. Monazite does not float readily using, for example, laurel amine or anionic collectors. Adsorption of the sodium oleate on the monazite increases with an increase in pH, indicating that monazite does not float in acid pH, while pyrochlore is readily floatable and is depressed at a pH greater than 10. Figure 24.1 shows the effect of pH on flotation of monazite, pyrochlore and zircon. 

India has very large deposits of monazite on the coastal shores of Kerala and Chennai. A typical mineral composition of this type of deposit is 60% ilmenite, 1.2% rutile, 5% zircon, 6.4% garnet, 4% silinanite, 16% quartz, 2.5-5% monazite and 1-7% shell. Research work involved different anionic collectors and pH during monazite flotation, along with the level of sodium silicate used as depressant. 

Collectors arc chemical reagents that selectively coat the particles to be floated with a water-repellanl surface that will adhere to air bubhlcs. Collectors generally are classified as cationic, anionic, or nonionic. Examples of collectors include the xanlhales, dithiophosphates. thiocarbonilides. and ihionocarbonales, all of which are anionic collectors... 

The inadvertent activation of a mineral can often result in an undesirable response to flotation. A typical example is quartz, a highly unreactive mineral whose recovery by flotation is therefore difficult. However, in the presence of metal cations, it can be activated to respond to anionic collectors, as shown by the data13 in Figure 3. It is of interest that the pH value at which flotation is effective can be related to that at which the monohydroxy complexes of the metal ions are predominantly stable, suggesting a specific adsorption of these species onto the quartz surface. In some cases this can be used for the selective depression of the quartz minerals in, for example, the flotation of pyrite in the presence of cationic collectors such as the long-chain amines. 

Dixit and Biswas124 dealt with the relationship between H+ an OH- concentrations and adsorption of an anionic collector on a mineral surface and its flotability. They used the system zircon-Na oleate. If Na oleate is dissolved in water the following equilibrium sets up ... 

O. Kangal, A. A. Sirkeci, and A. Guney, Flotation behaviour of huntite (Mg3Ca(C03)4) with anionic collectors. Internal. J. Mineral Processing 75(1-2) (2005). 

PZC and lEP are important parameters for surface characterization of oxide minerals. The flotation of these minerals is best understood in terms of the electrical double layer theories. Simple oxide minerals such as hematite, goethite, magnetite and corundum float well with cationic collectors above their PZC. Fig. 3.14 shows the flotation of goethite using both anionic and cationic collectors. The PZC of this mineral is pH 6.7. Anionic collectors are effective for goethite below pH 6.7 since the mineral is then positively charged. 

Consider reactions between metallic ions of wolframite and anionic collector ion to be as follows ... 

Tannins are mainly used as depressants for dolomite, calcite and silicate minerals in the flotation of scheelite, apatite, fluorite and copper sulfide. Like starch, tannins after modification by oxidation, sulfidization and aminization (tannin O, S and A, respectively) have been used as a depressant for hematite in the reverse flotation of quartz with oleic acid or dodecylamine as collectors [22]. Flotation results show quartz to be depressed by tannins in the order of tannin A > S at low concentrations of dodecylamine. When an anionic collector is used for the reverse flotation of Ca +-activated quartz with tannins as depressant for hematite, the order of depression is tannin A > O > S. 

What is the composition of Pamak, an anion collector manufactured by Hercules ... 

Oxides and Silicates with Anionic Collectors Part II, Trans. AIME, 258, 261 (1975). 

A. M. Gaudin and D. W, Fuerstenau, Quanz Flotation with Anionic Collectors, Trans. AIME,... 

E, Sorensen, Ox (he Adsorption or Some Anionic Collectors on Fluoride Minerals, J. Colloid... 

F. Z. Saleeb and H. S. Hanna, Flotation of Calcite end Quartz with Anionic Collectors, the... 

An original technological solution for phosphate separation has been proposed in [157]. The typical flow-sheet requires rather high consumptions of anionic collectors, e.g. fatty acid soaps. The authors have proposed a two-step flow-sheet in which fine particles are first floated with a minimum aminoacid consumption. The concentrate from prefloat is then floatated with a fatty acid/fuel oil emulsion. As a result, a phosphorite concentrate is produced which contains about 30 % P2O5, and the P2O5 recovety is over 93%. 

For example, as shown in Figure 10.36 (15), no adsorption of myristate (an anionic surfactant) occurs below the isoelectric point (pH 7.0) of chromite (even though the surfaces are oppositely charged), while essentially complete flotation is achieved at about pH 9.0 (when the surfactant and surface are similarly charged). The lack of flotation below the lEP was attributed to the limited solubility of myristic acid under these conditions. A similar behaviour has been observed for the flotation of haematite with myristate. Chemisorption of another anionic collector, octyl hydroxamate, has also been observed on haematite at pH 9.0 (15). 

For flotation studies, dodecylamine hydrochloride from Eastman Kodak Co. and purified sodium oleate from Fisher Scientific Co. were used as the cationic and anionic collectors, respectively. All other chemicals were reagent grade purchased from Fisher Scientific Co. HNO3 and KOH were employed as pH modifiers. Deionized water (D.l.) of less than 1.2 micromhos conductivity was used in this study. 

Tannin can also be used as the depressant of hematite in the reverse flotation of quartz activated by Ca " using anionic collector. 

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