By-Products of Porphyry Copper and Molybdenum Deposits

Author(s):  
David A. John ◽  
Ryan D. Taylor
Keyword(s):  
2020 ◽  
Author(s):  
Maurice Brodbeck ◽  
Sean McClenaghan ◽  
Balz Samuel Kamber ◽  
Patrick Redmond

<p>Porphyry copper deposits are predominantly mined for the major commodities Cu, Mo and Au. From some of these deposits, minor (trace) elements are also recovered as by-products (e.g. Ag, Pd, Te, Se, Bi, Zn, Pb). This list will potentially expand with the increasing demand for critical raw materials in modern energy-related technologies. Key components for such technologies are energy-critical elements (ECEs), many of which are classified as credit elements (e.g. Co, Ga, Ge and In). However, even if currently recovered as by-products, their deportment in copper ores and their overall distribution at the deposit scale have received little research attention. This gap in knowledge is limiting more effective recovery of ECEs. The same applies to elements that might incur refining penalties (e.g. As, Cd, Sb and Sn). Characterizing the trace element inventory of host mineral phases contributes to an improved understanding of the distribution of trace metals. By informing geometallurgy, element deportment studies can thus potentially promote economic and ecologic benefits in the form of improving recovery, adding value to ore resources and helping to reduce the dispersion of deleterious metals into the environment.</p><p>This study focused on the deportment of ECEs and precious metals in the northwestern high-grade section of the Bingham Canyon Cu-Mo-Au porphyry deposit. Contained Cu-(Fe-) sulphides were characterised with scanning electron microscopy and analysed by laser ablation (LA) ICP-MS for their metal endowment and for their potential use as discriminators of magmatic-hydrothermal processes. The availability of copper (iron) sulfides was found to exert principal control over the chalcophile trace element budget. The abundance of bornite and digenite primarily controls the Bi and Ag- budgets of the overall system and significantly affects variations in Te and Se. Chalcopyrite predominantly controls the Co, Ga and In budgets. By contrast, Ge, As, Cd, Sn, Sb and Au are not significantly controlled by the major sulfides indicating their residence in accessory phases. The presence of electrum and Ag-(Au) tellurides governs the distribution of Au, and most likely also the Te budget.<br>At the small scale relevant to mineral processing, the Bingham ore shows a particularly interesting phenomenon. Digenite (Cu<sub>9</sub>S<sub>5</sub>) is invariably present within bornite likely as the exsolution product of a copper-rich bornite solid solution. LA-ICP-MS analyses revealed that the exsolution process has resulted in a redistribution of trace elements, including some ECEs. Trace element partitioning between bornite and digenite is evident in element maps of the complex intergrowths. Silver, Te and Au strongly partition into digenite, while Se seems to retain its primary homogenous distribution, unaffected by exsolution. Elements that are preferentially retained in bornite (Sn and Bi), or at similar levels between the two sulphide species (In) show more complex zoning patterns in bornite. Zones of lowest concentration in bornite, peripheral around exsolved digenite grains, indicate stress-induced diffusion due to accumulating lattice distortions in bornite during digenite growth. The findings from digenite exsolution in bornite at Bingham show that relatively late, solid-state processes can result in complex deportment of precious metals and ECEs within copper-iron sulphides.</p>


1997 ◽  
Vol 161 ◽  
pp. 179-187
Author(s):  
Clifford N. Matthews ◽  
Rose A. Pesce-Rodriguez ◽  
Shirley A. Liebman

AbstractHydrogen cyanide polymers – heterogeneous solids ranging in color from yellow to orange to brown to black – may be among the organic macromolecules most readily formed within the Solar System. The non-volatile black crust of comet Halley, for example, as well as the extensive orangebrown streaks in the atmosphere of Jupiter, might consist largely of such polymers synthesized from HCN formed by photolysis of methane and ammonia, the color observed depending on the concentration of HCN involved. Laboratory studies of these ubiquitous compounds point to the presence of polyamidine structures synthesized directly from hydrogen cyanide. These would be converted by water to polypeptides which can be further hydrolyzed to α-amino acids. Black polymers and multimers with conjugated ladder structures derived from HCN could also be formed and might well be the source of the many nitrogen heterocycles, adenine included, observed after pyrolysis. The dark brown color arising from the impacts of comet P/Shoemaker-Levy 9 on Jupiter might therefore be mainly caused by the presence of HCN polymers, whether originally present, deposited by the impactor or synthesized directly from HCN. Spectroscopic detection of these predicted macromolecules and their hydrolytic and pyrolytic by-products would strengthen significantly the hypothesis that cyanide polymerization is a preferred pathway for prebiotic and extraterrestrial chemistry.


Author(s):  
Sumio Iijima

We have developed a technique to prepare thin single crystal films of graphite for use as supporting films for high resolution electron microscopy. As we showed elsewhere (1), these films are completely noiseless and therefore can be used in the observation of phase objects by CTEM, such as single atoms or molecules as a means for overcoming the difficulties because of the background noise which appears with amorphous carbon supporting films, even though they are prepared so as to be less than 20Å thick. Since the graphite films are thinned by reaction with WO3 crystals under electron beam irradiation in the microscope, some small crystallites of WC or WC2 are inevitably left on the films as by-products. These particles are usually found to be over 10-20Å diameter but very fine particles are also formed on the film and these can serve as good test objects for studying the image formation of phase objects.


2020 ◽  
Vol 3 (1) ◽  
pp. 20-25
Author(s):  
A.I. Zharinov ◽  
O.V. Kuznetsova ◽  
L.A. Tekutieva
Keyword(s):  

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