Jamesonite

Quer-schwlngung. /. transverse vibration, -spalte, /. transverse split or fissure, -spiess-glanz, m. jamesonite. -streifung, /. cross striping or striation. -Strom, m. cross current Elec.) wattless current, -sttick, n. 

However, it may seem that we have ignored the m, n, and p odd combinations that are also possible. For example, in jamesonite, Fe"Pb4Sb5Si4 [80], the mnp values are 034 (or 068), respectively (assuming one Fe(II) = 2 Cu(I)). We have successfully substituted europium into the structure to create a congru-ently melting, semiconducting FePb2Fu2Sb6Si4 [79]. This has a value of A B =... 

Opaque minerals include stibnite, jamesonite, cinnabar, gold, pyrite, pyrrhotite, arsenopyrite, marcasite, sphalerite, galena and chalcopyrite. 

Figures 2.6, 2.7 and 2.8 provided the evidence that there exists the critical upper and lower limit of pulp potential for collectorless flotation at certain pH. Figure 2.9 further demonstrated the flotation recovery of jamesonite as a function of potential at different pH. It is obvious that jamesonite has very good collectorless floatability in different potential range, which much depended on different pH. The...

The F h-pH diagram for jamesonite is given in Fig. 2.18. It may be seen from Fig. 2.18 that in acid and neutral solutions, the reactions producing elemental sulphur may render jamesonite surface hydrophobic and jamesonite shows good collectorless flotation. In alkaline solution, the hydrophilic species Fe, Pb ", HSb02, SbOj, are produced, the collectorless floatability of jamesonite becomes weaker, it may be attributed to the presence of Fe(OH)3 and Pb(OH)2 at the same time on the jamesonite surface. The relative amounts of hydrophobic sulphur and hydrophilic Fe(OH)3 and Pb(OH)2 perhaps determine the collectorless floatability of jamesonite. 

Figure 2.18 rpH diagram for jamesonite in aqueous solutions with elemental sulphur as metastable phase. Equilibrium lines correspond to dissolved species at 10 moFL... 

The voltammogram for jamesonite is given in Fig. 2.21. It can be seen that there are four obvious anodic peaks at the first cycle voltammetry. The peak current of api, aps and cp2 constantly increase with the number of cycle adding, but the peak height of ap2 and ap4 decreases at the second cycle and then keeps constant even by multi-cycle according to the experimental appearances. It was... 

Figure 2.21 Multi-voltammograms for jamesonite electrode in 0.1 mol/L KNO3 mixed phosphate buffer solution at pH = 6.86 and scanning rate of 50 mV/s...

The correlation between the amount of extracted sulphur and floatability was frirther investigated. Figure 2.27 represents the relationship between the recovery of marmatite, pyrrhotite and jamesonite and the amount of extracted sulphur at... 

The collectorless flotation recovery of marmatite, pyrrhotite and jamesonite and the amount of extracted sulphur as a function of pH are shown in Figs. 2.28, 2.29 and 2.30. Figure 2.28 shows that the trend of recovery of marmatite is consistent with change of the amount of extracted sulphiu. They all decrease with the increase of pH. In acidic pH media, both collectorless flotation recovery of marmatite and the amount of extracted sulphur from its surface are the maximum. 

Abstract The sodium sulphide-induced collectorless flotation of several minerals are first introduced in this chapter. The results obtained are that sodium sulphide-induced collectorless flotation of sulphide minerals is strong for pyrite while galena, jamesonite and chalcopyrite have no sodium sulphide-induced collectorless flotability. And the nature of hydrophobic entity is then determined through J h-pH diagram and cyclic voltammogram, which is element sulphur. It is further proved widi the results of surface analysis and sulphur-extract. In the end, the self-induced and sodium sulphide-induced collectorless flotations are compared. And it is found that the order is just reverse in sodium sulphide-induced flotation to the one in self-induced collectorless flotation. 

Flotation recovery of jamesonite as a function of Na2S concentration is shown in Fig. 3.3. It follows that the recovery of jamesonite is decreased by the addition of low dosage of Na2S at various pH. In contrast to self-induced collectorless flotation, the collectorless flotation of jamesonite is depressed in the presence of sodium sulphide. In alkaline pH range, the self-induced collectorless flotation of jamesonite is sharply depressed by the addition of Na2S. In acidic pH range, the... 

Figure 3.3 Flotation recovery of jamesonite as a function of Na2S concentration...

Figure 3.5 Sulphur-induced collectorless flotation recovery of pynhotites, jamesonite and marmatite as a function of NaaS concentration at pH = 8.8...

The results above show that the sodium sulphide-induced collectorless floatability of sulphide minerals is strong for pyrite. Galena, jamesonite and chalcopyrite have no sodium sulphide-induced collectorless floatability. Marmatite and pyrrhotite showed some sodium sulphide-induced collectorless floatability in certain conditions. 

Table 4.1 shows the measured rest potential of sulphide electrode in thio collector solutions at pH = 6.86 and the equilibrium potential calculated for possible processes. In terms of the mixed potential model, the reaction products should be metal collector salts between four thio collectors and galena and jamesonite and should be disulphide between four thio collectors and pyrite and... 

The influence of pulp potential on floatability of jamesonite is shown in Fig. 4.12 for an initial concentration of 1 x 10 mol/L ethyl xanthate (EX), dithiocarbamate (DDTC) and ammonium dialkyl dithio-phosphate (ADDP). If the upper and lower... 

Figure 4.12 Flotation recovery of jamesonite as a function of pulp potential in the presence of collector (collector concentration 10" mol/L, pH = 8.8)...

Figure 4.13 presents the lower (E h ) and upper (E h ) limiting flotation potential of jamesonite as a function of pH with collector concentration of 1 xl0 mol/L. It can be seen that the lower (E ) and upper (Et ) limiting flotation potential is changed with the pH value. The flotation of jamesonite may occur only at a range of pulp potential E < h < E - The flotation potential with DDTC as a collector is higher than that with EX as a collector. 

Figure 4.13 The lower (E ) and rqjper limiting flotation potential of jamesonite as a function of pH (1-EX, 2-DDTC, collector concentration 1 xlO" mol/L)...

Figure 4.14 is the Tafel curves of jamesonite under the conditions of different concentration of DDTC in natural pH solution. Obviously, the corrosive potential moves negatively and its corrosive current decreases with the DDTC concentration increasing. DDTC can obviously inhibit the anodic corrosion of jamesonite due to its chemisorption. 

In cathodic area, the Tafel slope in the presence of DDTC is bigger than that in the absence of DDTC, and the cathodic curves imder the conditions of different DDTC concentration are almost parallel and their Tafel slopes only change a little. These demonstrate that the chemisorption of DDTC on the surface of jamesonite electrode also inhibits the cathodic reaction, but the chemisorption amoimt of DDTC is a little and almost not affected by the DDTC concentration due to their negatively electric properties of DDTC anion and the electrode surface. This reveals that there is a little DDTC chemisorption on the mineral even if the potential is lower (i.e., negative potential). 

Figure 4.14 Tafel curves of jamesonite electrode in 0.1 mol/L KNO3 solution under the conditions of different DDTC concentration (unit of/ A/cm )...

The electrochemical resistance is smaller in the absence of DDTC, but increases four times in presence of DDTC. So the adsorption of DDTC on jamesonite results in reducing the reaction rate of the corrosive electrochemistry in open circuit potential. 

Table 4.2 EIS parameters of jamesonite electrode under the conditions of difiFerent cone, of DDTC...

As DDTC adsorbs on jamesonite electrode chemically, the double electric charge layer is treated as a plate capacitor, the capacitance C of the tight layer as a constant, and the change of the capacitance of the double electric charge layer is designated to the capacitance Ct of the diffusion layer. Thereby, the tight layer and the diffusion layer are looked upon as two series capacitances according to the method from Cooper and Harrison, then ... 

Therefore, the corrosive potential of jamesonite moves negatively with the DDTC concentration added. It promotes the anodic reaction of jamesonite. On the contrary, DDTC metal salt of the reaction production covered tightly the electrode surface inhibits its anodic reaction to result in the decrease of the corrosive current. There must be an optimum concentration of collector DDTC... 

---