Flotation separation

Collectors Fitting into Fattice Cavities. Lattice site fitting of collectors at sohd walls has been invoked as a means of explaining the selective behavior of amines (cationic coUectors) as reagents in the flotation-separation of soluble salt minerals such as KCl and NaCl (22). 

In general, collectors for the flotation separation of sulfides and precious metals contain at least one sulfur atom ia an appropriate bonding state. 

Sulfide collectors ia geaeral show Htfle affinity for nonsulfide minerals, thus separation of one sulfide from another becomes the main issue. The nonsulfide collectors are in general less selective and this is accentuated by the large similarities in surface properties between the various nonsulfide minerals (42). Some examples of sulfide flotation are copper sulfides flotation from siUceous gangue sequential flotation of sulfides of copper, lead, and zinc from complex and massive sulfide ores and flotation recovery of extremely small (a few ppm) amounts of precious metals. Examples of nonsulfide flotation include separation of sylvite, KCl, from haUte, NaCl, which are two soluble minerals having similar properties selective flocculation—flotation separation of iron oxides from siUca separation of feldspar from siUca, siUcates, and oxides phosphate rock separation from siUca and carbonates and coal flotation. 

Scrubbing andDesliming. Sylvinite ores in North America contain 1—6 wt % water-insoluble clays. A significant portion of these clays is less than 0.002 mm in diameter. If not removed or controUed in some manner, clay bodies that are dispersed in the flotation solution, ie, brine saturated with KCl and NaCl, absorb the amine coUector, which is added to effect flotation separation, and the coUector is rendered ineffective. Clay is the most troublesome impurity encountered in the processing of sylvinite ore. 

Foam Production This is important in froth-flotation separations in the manufac ture of cellular elastomers, plastics, and glass and in certain special apphcations (e.g., food products, fire extinguishers). Unwanted foam can occur in process columns, in agitated vessels, and in reactors in which a gaseous product is formed it must be avoided, destroyed, or controlled. Berkman and Egloff (Emulsions and Foams, Reinhold, New York, 1941, pp. 112-152) have mentioned that foam is produced only in systems possessing the proper combination of interfacial tension, viscosity, volatihty, and concentration of solute or suspended solids. From the standpoint of gas comminution, foam production requires the creation of small biibbles in a hquid capable of sustaining foam. 

Extraction and flotation separation of POMs as ion-pair with a bulky cation of Astrazone Violet (AV) with different organic solvents is investigated. Conditions for separation of dye excess from ion-pair PMo TiO j with polymethine dye AV ai e found. 

Figure 4 Schematic representation of a froth flotation separator.

This book systematically summarizes the researches on electrochemistry of sulphide flotation in our group. The various electrochemical measurements, especially electrochemical corrosive method, electrochemical equilibrium calculations, surface analysis and semiconductor energy band theory, practically, molecular orbital theory, have been used in our studies and introduced in this book. The collectorless and collector-induced flotation behavior of sulphide minerals and the mechanism in various flotation systems have been discussed. The electrochemical corrosive mechanism, mechano-electrochemical behavior and the molecular orbital approach of flotation of sulphide minerals will provide much new information to the researchers in this area. The example of electrochemical flotation separation of sulphide ores listed in this book will demonstrate the good future of flotation electrochemistry of sulphide minerals in industrial applications. 

The effect of DMPS on the flotation recovery of pyrrhotite and marmatite in the presence and absence of CUSO4 with butyl xanthate is shown in Fig. 5.16. It follows that the flotation of pyrrhotite and marmatite is greatly affected by DMPS addition. In the absence of cupric ion the recovery of pyrrhotite hardly exceeded 40%. At pH = 2, the recovery of marmatite is more than 90%, but the recovery sharply decreases to below 20% with pH increasing. These results show that pyrrhotite and marmatite can not be separated in the absence of cupric ion with DMPS as depressant and xanthate as a collector. In the presence of cupric ions, marmatite flotation improves under wide pH condition. The flotation of pyrrhotite is activated only aroimd pH = 2. The results demonstrate that flotation separation of copper-activated marmatite from pyrrhotite is possible in the presence of butyl xanthate and DMPS. 

At pH = 6, the flotation recovery of marmatite, arsenopyrite and pyrrhotite as a function of depressant dosage GX2 is given in Fig. 5.22. With the increase of GX2 dosage, the flotation recovery of these three minerals decreases. However, marmatite remains with reasonably high flotation recovery of above 70%, and arsenopyrite and pyrrhotite exhibit poor flotation with recovery of below 35% when the concentration of GX2 is above 120 mg/L. It indicates the possibility for flotation separation of marmatite from arsenopyrite and pyrrhotite by using 2,3-dihydroxyl propyl dithiocarbonic sodium as a depressant and butyl xanthate as a collector. 

The influence of pulp potential on the flotation of marmatite, arsenopyrite and pyrrhotite with 10 mol/L butyl xanthate as a collector in the presence of 150 mg/L 2,3-dihydroxyl propyl dithiocarbonic sodium (GX2) has been tested. Taking the flotation recovery to be 50% as a criterion, above which the mineral is considered to be floatable and otherwise not floatable, the upper and lower potential limits of the flotation of marmatite, arsenopyrite and pyrrhotite at different pH are presented in Fig. 5.25 and Table 5.1. It is evident that marmatite is floatable in some range of potential at various pH, whereas arsenopyrite and pyrrhotite are not floatable in the corresponding conditions. It suggests that the flotation separation of marmatite from arsenopyrite and pyrrhotite may be... 

Similarly, in the presence of 150mg/L TX4, copper ion still activates the xanthate flotation of marmatite as shown in Fig. 6.17. Marmatite starts flotation at a potential around 0.3 V with recovery of above 80%. At pH=4.5, the upper limit potential of flotation of marmatite can be high to above 0.6 V with a recovery about 90%. At pH = 6.5 and 9.2, the upper limit potential of flotation of marmatite decreases to about 0.5 V. Arsenopyrite can not be floated in the same conditions with a recovery of below 30% as seen from Fig. 6.18. This result also suggests that the flotation separation of marmatite from arsenop)aite may be accomplished by using TX4 as a depressant and xanthate as a collector in the presence of copper ion through the control of pulp potential and pH. 

DDTC has better selective action than xanthate in flotation separation of Pb-Zn-Fe sulphide ores in high lime medium. 

Grinding is essential for the liberation of sulphide minerals in order to achieve effective flotation. The grinding process, however, may also have a various effects on the flotation separation because of the galvanic interactions among the grinding media and the different minerals due to the high redox activity of sulphide mineral and iron media as well as thio-reagents. 

In flotation practice, the reducing environment produced in the grinding system may be useful for the interaction between galena and xanthate to form collector salt and not suitable for the formation of dixanthogen. It may promote the selective flotation separation of galena from pyrite. 

Chapter 10 Electrochemical Flotation Separation of Sulphide Minerals... 

Technological Factors Affecting Potential Controlled Flotation Separation of Sulphide Ores... 

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