Carrier flotation

Very finely divided minerals may be difficult to purify by flotation since the particles may a ere to larger, undesired minerals—or vice versa, the fines may be an impurity to be removed. The latter is the case with Ii02 (anatase) impurity in kaolin clay [87]. In carrier flotation, a coarser, separable mineral is added that will selectively pick up the fines [88,89]. The added mineral may be in the form of a floe (ferric hydroxide), and the process is called adsorbing colloid flotation [90]. The fines may be aggregated to reduce their loss, as in the addition of oil to agglomerate coal fines [91]. 

Piggyba.ckFlota.tlon, This process has also been called carrier flotation. The principle is based on the flotation of fine particles adhering to others by mutual coagulation. Thus when one is floated the other, which is usually more difficult to float, is also collected. 

In conventional chemical pulping systems, micronized talc is used for pitch control. The mechanism is not well understood, but talc does adsorb on the pitch and detackify it, preventing it from agglomerating and attaching on equipment. In de-inking talc is used both to enhance ink removal in conventional screening/centrifugation methods and as a carrier in flotation systems. 

The term three-phase fluidization, in this chapter, is taken as a system consisting of a gas, liquid, and solid phase, wherein the solid phase is in a non-stationary state, and includes three-phase slurry bubble columns, three-phase fluidized beds, and three-phase flotation columns, but excludes three-phase fixed bed systems. The individual phases in three-phase fluidization systems can be reactants, products, catalysts, or inert. For example, in the hydrotreating of light gas oils, the solid phase is catalyst, and the liquid and gas phases are either reactants or products in the bleaching of paper pulp, the solid phase is both reactant and product, and the gas phase is a reactant while the liquid phase is inert in anaerobic fermentation, the gas phase results from the biological activity, the liquid phase is product, and the solid is either a biological carrier or the microorganism itself. 

Wang, Y.C., Carrier Flotation of Anatase from Clay and its Physicochemical Mechanisms, D.E.Sc. Thesis, Columbia University, New York, 1980. 

Each of the sulphide minerals, which are PGM carriers (i.e. pyrrhotite, pyrite, pentlan-dite, etc.) have different flotation properties under some flotation conditions. The selectivity between sulphide minerals and gangue minerals is relatively poor in principle, and in the majority of cases, a hydrophobic gangue depressant has to be used. 

The major carriers of PGM are a variety of minerals and alloys, where the flotation properties of the PGM minerals and alloys are not well defined. These ores have very little to no sulphides present that are PGM carriers. 

The PGM carriers in this ore include a variety of PGM minerals (sperrilite) and its alloys. The main problems identified associated with processing this ore type were (a) poor concentrate grade, (b) low rate of PGM flotation, (c) excessive chromium reporting to the PGM concentrate and (d) high collector consumption. 

Oil flotation, liquid-phase agglomeration, carrier flotation... 

Some modifications to the standard froth-flotation process have been developed in order to improve separation and recovery efficiency including carrier flotation, emulsion flotation, and floe flotation. These are all aimed at making very fine particles amenable to flotation, or at improving the efficiency of their flotation. 

In carrier flotation, small-sized (several pm diameter) particles become attached to the surfaces of larger particles (perhaps 50 pm diameter, the carrier particles) [630]. The carrier particles attach to the air bubbles and the combined aggregates of small desired particles, carrier particles, and air bubbles float to form the froth. An example is the use of limestone particles as carriers in the flotation removal of fine iron and titanium oxide mineral impurities from kaolinite clays [630]. The use of a fatty acid collector makes the impurity oxide particles hydrophobic these then aggregate on the carrier particles. In a sense, the opposite of carrier flotation is slime coating, in which the flotation of coarse particles is decreased or prevented by coating their surfaces with fine hydrophilic particles (slimes). An example is the slime coating of fine fluorite particles onto galena particles [630],... 

Emulsion flotation is analogous to carrier flotation. Here, small-sized particles become attached to the surfaces of oil droplets (the carrier droplets). The carrier droplets attach to the air bubbles and the combined aggregates of small desired particles, carrier droplets, and air bubbles float to form the froth. An example is the emulsion flotation of submicrometre-sized diamond particles with isooctane. Emulsion flotation has also been applied to the flotation of minerals that are not readily wetted by water, such as graphite, sulfur, molybdenite, and coal [623]. Some oils used in emulsion flotation include mixed cresols (cresylic acid), pine oil, aliphatic alcohols, kerosene, fuel oil, and gas oil [623], A related use of a second, immiscible liquid to aid in particle separation is in agglomeration flocculation (see Section 5.6.4). 

Rubio, J. and H. Hoberg (1993). Process of separation of fine mineral particles by flotation with hydrophobic polymeric carrier. Int. J. Mineral Process. 37, 1-2, 109-122. Sincero, A. P. and G. A. Sincere (1996). Environmental Engineering A Design Approach. Prentice Hall, Upper Saddle River, NJ. 

Trace amounts of Te were separated with Se as carrier (after the reduction to the element) by flotation with xylene [8]. 

Conventional flotation processes can be made applicable to the treatment of Ases simply by preaggregating them among themselves or with another carrier material. Techniques in this category include floccflotaiion, carrier flotation (ultraflotation), and spherical agglomeration. 

In this technique, known also as piggyback flotation, a carrier material is used for floating the line particles. For example, utetase is removed on a commercial scale from clay for use in the puper iedustry by using calcite as the carrier. While anatase does not float by itself, it is cofloated with a coarse auxiliary mineml such as calcite. 

Adsorbing colloid flotation (adsorption onto or coprecipitalion with a carrier floe which is floated)... 

Some modifications to the standard froth flotation process have been developed in order to improve separation and recovery efficiency including carrier flotation. 

Uses Solvent in cosmetics solvent, diluent, carrier for personal care prods, for sprays solvent for coatings, odorless alkyd/actylic paints thinner cleaner defoamer in processing foods in coatings on fruits/ vegetables/egg shells in froth flotation cleaning of vegetables in insecticides for processed foods... 

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