Particles copper sulfide

In the flotation process, the powdered ore is mixed with water and a frothing agent such as pine oil. A stream of air is blown through the mixture to produce froth. The gangue in the ore, which is composed of sand, rock, and clay, is easily wetted by the water and sinks to the bottom of the container. In contrast, a copper sulfide particle is hydrophobic— it is not wetted by the water. The copper sulfide particle becomes coated with oil and is carried to the top of the container in the froth. The froth is removed continuously, and the floating copper sulfide minerals are recovered from it. 

FIGURE 9.4-1 Schematic drawing illustrating the leaching of a matrix mineral fiagroeni containing disseminated copper sulfide particles. 

It is found that the dissolution of zinc sulfides occurs more rapidly when they are in contact with copper sulfide or iron sulfide than when the sulfides of these types are absent. This enhancement is brought about by the formation of a galvanic cell. When two sulfide minerals are in contact, the condition for dissolution in acidic medium of one of the sulfides is that it should be anodic to the other sulfide in contact. This is illustrated schematically in Figure 5.3 (A). Thus, pyrite behaves cathodically towards several other sulfide minerals such as zinc sulfide, lead sulfide and copper sulfide. Consequently, pyrite enhances the dissolution of the other sulfide minerals while these minerals themselves understandably retard the dissolution of pyrite. This explains generally the different leaching behavior of an ore from different locations. The ore may have different mineralogical composition. A particle of sphalerite (ZnS) in contact with a pyrite particle in an aerated acid solution is the right system combination for the sphalerite to dissolve anodically. The situation is presented below ... 

Some of the discharged sulfide particles settle onto the chimney s exterior, where they are buried by the outward growth of anhydrite. Sulfide precipitation within the chimneys, causes copper, zinc, and iron sulfides to deposit and partially replace the anhydrite. Chimneys can build to several meters in height and their orifices range in diameter from 1 to 30 cm. Both the smoke and the chimneys are composed of polymetallic sulfide minerals, chiefly pyrrhotite (FeS), pyrite (FeS2), chalcopyrite (CuFeS2), and sphalerite or wurtzite (ZnS). 

XPS has been of use in revealing the oxidation of MC species in LB films. For example with films containing CdS, constructed from a mixed BeH/octadecyl amine monolayer on a subphase of stabilized CdS particles, only one oxygen state was found (79). By contrast, three oxygen states were found for the colloid in solution, indicating that the CdS in the film is protected from oxidation. This result correlated well with an observation that copper sulfide made in an LB film is resistant to oxidation when compared to copper sulfide prepared analogously in solution (9). The decomposition, via oxidation, of PbS made in films of StH has been followed by XPS (68,70). One study found that the decomposition rate of PbS was much slower for films deposited at faster rate (70). It was suggested that films deposited at the faster deposition rate were more ordered and this presented a barrier to PbS decomposition via oxidation. 

Aciivators are chemical reagenls. which alter the surface of a sulfide so that it can absorb a collector and final. Cupric sulfate is the most widely used activator. For example, xamhatc as a collector will not readily float sphalerite, but the addition of cupric sulfate to the pulp changes the surface of the sphalerite particles to copper sulfide. Xamhate then will readily fioat the activated sphalerite as it behaves similarly to copper sulfide. 

The concept of direct attack mechanisms as direct contact phenomena requiring intimate physical contact between the mineral surface and the organism requires some precise definition. Vanselow (1976) has thrown some light on the possible physical interactions between cells and minerals in studies on the effects of dilution on the rates of oxygen uptake by T. ferrooxidans strains in the presence of synthetic covellite. The dilution of a slurry will lower the rate of copper sulfide oxidation per unit volume, and the relationship between the dilution factor, and the factor by which the oxidation rate is lowered, will depend upon the nature of the physical interaction between the cells and the mineral particles. Three principal situations were postulated, namely, that in which the oxidation was carried out by cells... 

Composition of Water. Water is composed of hydrogen and oxygen [1] - one often hears these or similar statements in classrooms about compounds, which supposedly contain certain elements. These expressions arise from a time when it was common to analyze and find out which elements make up certain compounds. Insiders know the background of these statements - for novices however, they will lead to school-made misconceptions students would associate the substances copper and sulfur in the black copper sulfide, particularly as experiments show that one can remove these elements out of copper sulfide. It would be better, in introductory classes, to point out that the metal sulfides could be produced from metals and sulfur or to show that one can obtain the elements from the compound. Later on, if one is aware of atoms and ions as the smallest particles of matter, one can expand on these statements, that the compound contains special atoms or ions, that one water molecule contains two H atoms and one O atom connected and arranged in a particular spatial structure. But the pure sentence water contains hydrogen and oxygen will develop school-made misconceptions ... 

Although this strategy works well for copper-sulfide, copper-selenide, and copper telluride particles, it has not been shown that related silver- and gold-chalco-... 

Nanocrystalline metal (silver and copper) and metal sulfide (silver sulfide, cadmium sulfide, and lead sulfide) particles were prepared via RESOLV (Rapid Expansion of a Supercritical Solution into a Liquid SOLVent) with water-in-carbon dioxide microemulsion as solvent for the rapid expansion. The nanoparticles were characterized using UV/vis absorption. X-ray powder diffraction, and transmission electron microscopy methods. The results of the different nanoparticles are compared and discussed in reference to those of the same nanoparticles produced via RESOLV with the use of conventional supercritical solvents. 

A rather special problem can sometimes arise when analyzing certain t)rpes of copper sulfide ore from an open cast mine. In this case it can happen that, close to the surface, where air has been in contact with the sulfide ore, the ore can be oxidized. Thus a particle of chalkopyrite CuFeSa may be converted to CuFeOa. Where the oxidation is limited to the outside of the particle the effect is called rimming the outside of the particle is copper iron oxide, but the inside of the particle is copper iron sulfide. ITie thickness of the oxide layer may be dependent on the depth of the mine from which the ore is being taken. As has been previously stated, while fusion of the sample with a borate flux would probably solve the problem, special circumstances may prevent use of this additional sample preparation step. The problem for the analyst is to judge when special precautions have to be taken. 

Applying this concept to the example of the partially oxidized copper sulfide ores, by measurement of Cu Ka and Cu La lines, one can use the intensity ratio of these two lines to predict when the outermost portion of a given particle changes composition. As an example, Table 13.2 shows a small portion of the data taken... 

Braithewaite and Madsen and Wadsworth used the simplified continuity equation for copper sulfide ores using finite difference approximations. The spherical ore matrix was divideid into j concentric shells of thickness Ar, with 1 corresponding to the center and = n to the outer edge of the spherical matrix particle. The term (R may be evaluated using the equation... 

Fig. IV.4. Charge of lead sulfide particles on copper (a) or cadmium (b) substrate as a function of potential impressed on substrate (1) natural powder (2) powder with metallic properties after vacuum treatment (3) powder with non-metallic properties after treatment in sulfur vapor.

For example, zinc sulfide, copper sulfide, cadmium sulfide, and lead sulfide Qdots were attached to four different secondary antibodies to detect four different proteins [56]. The four different Qdots were dissolved to yield four different metal ions, each associated with a different protein. These were measured by stripping voltammetry after dissolution of the particles following the binding steps. Multiple metal striped rods, spheres or alloy rods were also used for multiplexing. The rods were capped with a gold end for attachment to Ab2. Upon dissolution, these materials give a series of metal stripping peaks whose peak potentials and relative intensities are associated with individual analyte proteins [38]. Such bar code labels have the potential to determine many proteins in patient samples, but this has yet to be reported. 

Comparison of octyl isothiourea and dixanthogen in the flotation of copper-sulfide ore is listed in Table 1.8. The particle size of copper-sulfide ore is 10 mesh. And the mass fraction of copper in copper-sulfide ore is 4-4.5 %. It can be seen that the flotation performance of octyl isothiourea is better than that of dixanthogen. 

A representation of the flotation process for enrichment of copper sulfide ore. The relatively light sulfide particles are suspended In the water-oil-detergent mixture and collected as a froth. The denser rxky material sinks to the bottom of the container. 

The discovery suddenly gave an explanation of the origins of many massive workable sulfide ores. The sulfide particles were baked into the sediments and preserved. The deposits may later have moved from sea to land in geological processes. Many of the ores we find in the earth s crust have been formed in this way, among others probably the famous ores in the Trudos mountains on the copper island of Cyprus. 

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