Effect of the collector

In the electrospinning process, usually a conductive material is used to cover the collecting media. Aluminium foil is one of the most common conductive materials that are used for collection of fibers onto it. By using the conductive material covering, a stable potential difference can be obtained between the tip and the collector. Conductive collectors attract more jets on the surface of the collector, resulting in a higher amount of fiber deposition. For nonconductive 

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Average effectiveness of the collector 0.3 Average temperature increase of the air preheated by solar energy (July, Hungary) at RPM 1090 per min, 2.9°C at RPM 475 per min, 9.86°C Output of the auxiliary air heater 93 kW Medium-scale crop-dryer with unglazed collector is presented in Ref. [218]. 

Excess collector can also reduce the separation by forming micelles in the bulk which adsorb some of the colhgend, thus keeping it from the surface. This effect of the micelles on Ki for the colhgend is given theoretically [Lemhch, Principles of Foam Fractionation, in Periy (ed.). Progress in Separation and Purification, vol. 1, Interscience, New York, 1968, chap. 1] by Eq. (22-44) [Lemlich (ed.). Adsorptive Bubble Separation Techniques, Academic, New York, 1972] if F, is constant when C, > C-... 

Other types of inertial collectors which might be used for particulate separation from a carrying gas stream depend on the same theoretical principles developed for cyclones. Table 29-2 summarizes the effect of the common variables on inertial collector performance. 

The Smoluchowski-Levich approach discounts the effect of the hydrodynamic interactions and the London-van der Waals forces. This was done under the pretense that the increase in hydrodynamic drag when a particle approaches a surface, is exactly balanced by the attractive dispersion forces. Smoluchowski also assumed that particles are irreversibly captured when they approach the collector sufficiently close (the primary minimum distance 5m). This assumption leads to the perfect sink boundary condition at the collector surface i.e. cp 0 at h Sm. In the perfect sink model, the surface immobilizing reaction is assumed infinitely fast, and the primary minimum potential well is infinitely deep. 

Effect of secondary collectors on PGM from the Norilsk (Russia) disseminated Cu/Ni-PGM ore... 

Types of secondary collectors were extensively examined in research work. Figure 18.6 shows the effect of secondary collectors on the PGM grade-recovery relationship. 

Xanthated fatty acid mixture is a new line of collectors, specifically designed for beneficiation of oxide copper ores that contain dolomitic and carbonaceous gangue minerals [19]. This collector was developed after extensive laboratory development testwork. The effectiveness of this collector was compared to a standard xanthate collector in a series of continuous locked cycle tests (Table 19.5). 

Effect of different collectors on tin flotation from the Union and Rooiberg old tailings... 

Limited research work has been conducted on these ores, but have indicated that REO cannot be recovered using either fatty acid or sodium oleate. It was, however, found that a mixture of sulphosuccinamate and phosphate ester modified with alkylsulphate can recover REO and zircon efficiently. Figure 24.5 shows the effect of above collector mixture (KBX3) on REO recovery from complex RE0-Zr02 ores. Oxalic acid and fatty acid (FA3) were not so effective compared to collector KBX3. 

Effect of different collectors on monazite flotation from the Chennai beach sand... 

Effect of different collectors on flotation of monazite using sodium oleate as the activator... 

Effect of different collectors on rutile flotation from the Cerro Blanco rutile ore from Chile... 

Most recently, development testwork was performed on a large perovskite deposit (Powderhom) located in the USA. An effective beneficiation process was developed, where a concentrate assaying >50% Ti02 was achieved in the pilot plant confirmation tests [7]. During this development testwork, a number of different collectors were examined at different pH values. Figure 25.5 shows the effect of the different collectors on perovsikte flotation. The most effective collector was phosphoric acid ester modified with either fatty alcohol sulphate or petroleum sulphonate. 

During research development testing, a fairly large number of collectors were examined, mainly phosphoric acid esters that were modified with different secondary collectors. Figure 25.9 shows the effect of different collectors and pHs on ilmenite flotation. 

In many cases, it is necessary to modify the surface of the other constituent so that it does not adsorb the collector or promoter. This is effected by means of materials known as modifiers which are either adsorbed on the surface of the particles or react chemically at the surface, and thereby prevent the adsorption of the collector or promoter. Mineral acids, alkalis, and salts are frequently used for this purpose. 

Abstract This chapter reviews the development of froth flotation achieved in the past one hundred years and accounts for the achievements of the theory of flotation of sulphide minerals in four aspects, which are the natural flotahility of sulphide minerals, the role of oxygen in the flotation of sulphide minerals, the interaction of collectors with sulphide minerals, the effect of the semi-conductor property of sulphide minerals and electrochemical behaviors in the grinding system. Furthermore, the purpose of this book is revealed in the end. 

The first class of chemical additives to be considered is the regulator, a compound that affects the adsorption of the collectors. Regulators, like catalysts, may be positive or negative in their role. For the case in which the collector adsorption is enhanced, the regulator is called an activator when the effect is negative, it is called a depressant. Regulators are frequently compounds that control the pH and sequester metallic cations that would otherwise compete with the mineral particle surfaces for the surface-active collectors. The pH affects not only the availability of certain collectors, but also the charge of the mineral particles (see Chapter 11,... 

In the collectors used, R is generally in the C2 to C6 range. Xanthates are readily oxidized to dixanthogens, and the extent of this reaction may have a big effect on the efficiency of the collector. 

ACTIVATOR. 1. A substance that renders a material or a system reactive commonly, a catalyst. 2. A special use of this term occurs in the flotation process, where an activator assists the action of the collector. 3. An impurity atom, present in a solid, that makes possible the effects of luminescence, or markedly increases their efficiency. Examples are copper in zinc sulfide, and thallium in potassium chloride. See also Enzyme. 

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