Menshikovite Pd3Ni2As3 and associated minerals of sulphide ores within the Eastern flank of the Oktyabrsky deposit (Norilsk ore field)

Author(s):  
E. M. Spiridonov ◽  
S. N. Belyakov ◽  
N. N. Korotayeva ◽  
K. V. Egorov ◽  
Yu. A. Ivanova ◽  
...  

Significant amount of menshikovite (rare palladium and nickel arsenide) Pd3Ni2As3 was found on the Eastern flank of the Oktyabrsky deposit (Norilsk ore field), near the contact of solid and impregnation sulfide Co-Ni-Cu ores among magnetite-plagioclase-fassaite skarns. Sulfide material of both ores consists of chalcopyrite, pentlandite, pyrrhotite and cubanite aggregates, which are the products of subsolidus transformations of high-temperature solid solutions Iss3, Iss4 and subordinate Mss; with interpositions of later Se-galenite. Menshikovite in association with mertieite-II, silver-gold (fineness 756–706), golden-electrum (fineness 694–672), kotulskite, moncheite, rare altaite, hessite, naldrettite and melonite forms small (up to 30 microns) metasomatic growths on the contact of silicate matrix and magmatogenic sulfide aggregates. The average composition of menshikovite is close to theoretical data: (Pd2,98Ru0,03)3,01(Ni1,89Fe0,-08Co0,01)1,98 (As2,94Se0,04Bi0,02Sn0,01)3,01. Sperrylite metacrystals cut the borders of menshikovite accretions as well as other minerals of precious metals and contain “corroded” inclusions. This association of minerals of noble metals has arisen under the increased activity of As, Te, Sb, Bi and low activity of Sn in fluids. Menshikovite is typical for Pd-rich ores of the Oktyabrsky Deposit, while mayakite PdNiAs (another palladium and nickel arsenide) is relatively widely developed in ores of the Talnakh Deposit (Mayak mine and partly Komsomolsky mine) and the Norilsk-I. Perhaps, such a distribution of palladium-nickel arsenides is an element of mineral zonality of the Norilsk ore field.

2018 ◽  
Vol 82 (2) ◽  
pp. 367-373 ◽  
Author(s):  
Sergei F. Sluzhenikin ◽  
Vladimir V. Kozlov ◽  
Chris J. Stanley ◽  
Maria L. Lukashova ◽  
Keith Dicks

ABSTRACTVymazalováite, Pd3Bi2S2 is a new platinum-group mineral discovered in the Komsomolsky mine of the Talnakh deposit, Noril'sk district, Russia. It forms small (from a few μm to 20–35 µm) inclusions or euhedral grains in intergrowths of polarite, sobolevskite, acanthite and unnamed (Pd,Ag)5BiS2 in aggregates (up to ~200 µm) in galena and rarely in chalcopyrite. It occurs with telargpalite, cooperite, braggite, vysotskite, sopcheite, stibiopalladinite, sobolevskite, moncheite, kotulskite, malyshevite, insizwaite, Au-bearing silver and the newly described mineral kravtsovite (PdAg2S) in association with pyrite, chalcopyrite and galena in vein-disseminated mineralization in skarn rocks. Synthetic vymazalováite is brittle; it has a metallic lustre and a grey streak. In plane-polarized reflected light, vymazalováite is creamy grey and appears slightly brownish against galena in the assemblage with chalcopyrite. It exhibits no internal reflections. Average reflectance values in air for natural and synthetic vymazalováite are (R natural, R synthetic in %) are: 46.35, 45.7 at 470 nm, 47.65, 47.45 at 546 nm, 48.5, 48.2 at 589 nm and 49.5, 49.0 at 650 nm. Seven electron probe micro-analyses of vymazalováite give an average composition: Pd 40.42, Bi 49.15, Ag 0.55, Pb 1.02, S 7.77 and Se 0.26, total 99.17 wt.%, corresponding to the empirical formula Pd3.05(Bi1.89Ag0.04Pb0.04)Σ1.97(S1.95Se0.03)Σ1.98 based on a total of 7 atoms per formula unit. The simplified formula is Pd3Bi2S2. The mineral is cubic, space group I213, with a = 8.3097(9) Å, V = 573.79(1) Å3 and Z = 4. The density calculated on the basis of the empirical formula and cell dimensions of synthetic vymazalováite is 9.25 g/cm3. The strongest lines in the powder X-ray diffraction pattern of synthetic vymazalováite [d in Å (I) (hkl)] are: 4.15(32)(200), 2.93(78)(220), 2.40(100)(220), 2.08(53)(400), 1.695(34)(422), 1.468(35)(440) and 1.252(31)(622). The structural identity of natural vymazalováite with synthetic Pd3Bi2S2 was confirmed by electron back-scatter diffraction measurements on the natural sample. This new mineral honours Dr Anna Vymazalová of the Czech Geological Survey, Prague.


2020 ◽  
Vol 26 (8) ◽  
pp. 40-48
Author(s):  
Yu. Rubtsov ◽  
◽  
А. Trubachev ◽  
E. Voronov ◽  
A. Lavrov ◽  
...  

Since the cost of gold has increased by an order of magnitude over the past 20 years, gold mining began to be carried out from ores that are not previously acceptable for heap leaching (HL) technology – these are refractory ores with thin and ultrafine inclusions of precious metals, ore with an increased silver content. In the Russian Federation, classical representations in the field of gold and silver HL prevail in design solutions. At the same time, the problem of silver leaching is considered in terms of the associated extraction of the main component. This approach is determined by a limited set of technological measures that have become an integral part of the classic technological regulation: ore crushing to the class –200–40 mm, sodium cyanide consumption at the level of 0,5 kg/t; pH value – 10,5; cycle duration 65 days or more; gold concentration in production solutions – fractions, mg/l; using activated carbon for sorption of noble metals. Processing ores with silver contents of 30 g/t and a more classical approach to gold HL does not allow to increase the degree of extraction. There is a need to modernize the circuit or change the parameters of the technological regulations. The object of the study was a sample of poor quartz ore provided by the customer developing one of the gold and silver deposits of the Far Eastern Federal District, the object was to increase the degree of leaching of silver from poor gold-bearing ores without changing the technological scheme and without attracting additional mining equipment. Critical analysis of literary data was carried out and the main directions of gold production from poor gold-bearing ores were identified. Chemical and mineralogical compositions of silver-containing minerals and ore rocks were investigated. Forms of association of silver with ore minerals and rocks have been established. The option of physical and chemical activation of increase of reactivity of cyanide solutions during heap leaching of silver from poor gold-bearing ores is chosen. In laboratory conditions, it was found that an increase in the concentration of sodium cyanide by 6 times or more contributes to a satisfactory extraction of gold both in agitation and percolation leaching of silver. However, in the latter case, the positive result was obtained only with the use of solutions with increased reactivity


2010 ◽  
Vol 2010 ◽  
pp. 1-12 ◽  
Author(s):  
Abdul-Majeed Azad ◽  
Desikan Sundararajan

Fuel processors are required to convert sulfur-laden logistic fuels (jet fuels, diesel, and coal) into fuel cell quality hydrogen-rich reformate with little or no sulfur for extended periods. Sulfur poisons and deactivates the reforming catalyst, therefore, sulfur-tolerant catalysts ought to be developed. In this paper, the development, characterization, and evaluation of a series of nanoscale ceria-supported reforming catalysts containing three noble metals in low concentration (1 wt% ≤ total metal loading ≤ 1.33 wt%) for the steam-reforming of kerosene (a JP-8 surrogate) are reported. Their performance is quantified in terms of H2yield, tolerance towards sulfur in the fuel, and the on-stream stability and compared with that of monometal and bimetal analogs under identical conditions. Due to the inherent cooperative synergy, a trimetal catalyst was found far superior to its mono- and bimetallic analog containing same amount of the precious metal loading in terms of quality of the reformate (measured by H2level in steady-state) as well as the catalyst longevity on-stream prior to deactivation. At the same time a mechanistic correlation between the distinct role of a given precious metal and the extent of its loading in each of the formulations and quality of the corresponding desulfurized H2-rich reformate was discovered.


2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Abdul-Majeed Azad ◽  
Desikan Sundararajan

Fuel processors are required to convert sulfur-laden logistic fuels into hydrogen-rich reformate and deliver to the fuel cell stack with little or no sulfur. Since sulfur poisons and deactivates the reforming catalyst, robust sulfur-tolerant catalysts ought to be developed. In this paper, the development, characterization and evaluation of a series of reforming catalysts containing two noble metals (with total metal loading not exceeding 1 weight percent) supported on nanoscale ceria for the steam-reforming of kerosene is reported. Due to inherent synergy, a bimetallic catalyst is superior to its monometallic analog, for the same level of loading. The choice of noble metal combination in the bimetallic formulations plays a vital and meaningful role in their performance. Presence of ruthenium and/or rhodium in formulations containing palladium showed improved sulfur tolerance and significant enhancement in their catalytic activity and stability. Rhodium was responsible for higher hydrogen yields in the logistic fuel reformate. Duration of steady hydrogen production was higher in the case of RhPd (75 h) than for RuPd (68 h); hydrogen generation was stable over the longest period (88 h) with RuRh containing no Pd. A mechanistic correlation between the characteristic role of precious metals in the presence of each other is discussed.


2013 ◽  
Vol 825 ◽  
pp. 301-304 ◽  
Author(s):  
Aleksander Bulaev ◽  
Maxim I. Muravyov ◽  
Tatyana Pivovarova ◽  
Natalya V. Fomchenko ◽  
Tamara F. Kondrat'eva

Mining and metallurgical treatments of sulphide ores are characterised by present significant losses of non-ferrous and precious metals as different types of waste. These elements are accumulated in heaps due to the lack of efficient technology for the recovery of the metals from metallurgical waste. The treatment of two types of industrial metallurgical waste (copper converter slag and old flotation pyrite tailings) containing non-ferrous and precious metals were examined in the laboratory. Leaching of the slag containing 2.74% Cu (as digenite, bornite, and free metal) and 2.49% Zn (as a ferrite ZnFe2O4 and silicate) by an Fe3+-containing solution was studied. The effect of various experimental parameters on the leaching dynamics of copper, zinc, and iron under batch conditions was investigated. The following experimental parameters were recommended: a pH of 1.5, a pulp density of 10% (w/v), a temperature of 70 °C, and an initial Fe3+ concentration of 15 g/L. Leaching under these conditions resulted in the solubilisation of 89.4% copper and 35.3% zinc within 2.5 hours. Percolation leaching of the pyrite tailings containing 0.29% Cu (as chalcopyrite), 0.26% Zn (as sphalerite), 0.00007% gold, and 0.00108% silver was also studied. Acidic percolation leaching and the resulting biooxidation lasting 134 days resulted in the solubilisation of 73.4% zinc and 50.8% copper. The recovery rates of gold and silver from the bioleaching residues by cyanidation were 57.2% and 50.7%, respectively. The data obtained in the present work may be used to estimate the operating parameters for the industrial-scale processing of non-ferrous and precious metals from mining and metallurgical waste.


2021 ◽  
Author(s):  
Zhuang Ma ◽  
Binbin Jin ◽  
Yalin Guo ◽  
Xuejun Li ◽  
Guodong Yao ◽  
...  

<p>Gamma (γ)-valerolactone (GVL) is a promising liquid for energy and carbon-based chemicals. Although many researches regarding the GVL synthesis from carbohydrate biomass, most of them involve the use of noble metals accompanying with the high-purity and high-pressure gaseous hydrogen, existing high cost in large-scale application and safety risk during the transportation and operation process. In this paper, the cheap metal Fe was employed as a reductant for splitting water to produce hydrogen under mild hydrothermal conditions, and commercial Raney Ni was used as a catalyst for in situ hydrogenation of biomass-derived levulinic acid (LA). More than 95% yield of GVL can be attained at 150 <sup>o</sup>C for 2 h and ~ 90% yield of GVL was also achieved at 100 <sup>o</sup>C by increasing the reaction time to 5 h. Furthermore, Raney Ni remains the stable catalytic activity after being recycled for 4 times at 150 <sup>o</sup>C. This work provides a safe and facile process for highly efficient hydrogenation of biomass-derived LA to GVL without precious metals.</p>


2021 ◽  
Author(s):  
Zhuang Ma ◽  
Binbin Jin ◽  
Yalin Guo ◽  
Xuejun Li ◽  
Guodong Yao ◽  
...  

<p>Gamma (γ)-valerolactone (GVL) is a promising liquid for energy and carbon-based chemicals. Although many researches regarding the GVL synthesis from carbohydrate biomass, most of them involve the use of noble metals accompanying with the high-purity and high-pressure gaseous hydrogen, existing high cost in large-scale application and safety risk during the transportation and operation process. In this paper, the cheap metal Fe was employed as a reductant for splitting water to produce hydrogen under mild hydrothermal conditions, and commercial Raney Ni was used as a catalyst for in situ hydrogenation of biomass-derived levulinic acid (LA). More than 95% yield of GVL can be attained at 150 <sup>o</sup>C for 2 h and ~ 90% yield of GVL was also achieved at 100 <sup>o</sup>C by increasing the reaction time to 5 h. Furthermore, Raney Ni remains the stable catalytic activity after being recycled for 4 times at 150 <sup>o</sup>C. This work provides a safe and facile process for highly efficient hydrogenation of biomass-derived LA to GVL without precious metals.</p>


Author(s):  
И.А. Богуш ◽  
Г.В. Рябов ◽  
В.И. Черкашин ◽  
Н.А. Исаева

Объектами исследования являются терригенные породы, входящие в состав Тоханского комплекса (Тоханский покров), расположенные в пределах Передового хребта Северного Кавказа и прослеженные на протяжении более 200 километров. Тоханский комплекс сложен пелитоморфными углеродсодержащими отложениями (черными сланцами) с подчиненными проявлениями вулканогенных, глинистокремнистых, глинистокарбонатных и псаммитовых пород, испытал зеленокаменный метаморфизм. Целью работы был анализ геохимических особенностей углеродсодержащей черносланцевой герцинской толщи Северного Кавказа. Специфическим для черных сланцев является комплекс элементов, типоморфных для ультрамафитовых пород: хром, кобальт, никель, титан, марганец, ванадий, фосфор. Халькофильные элементы гидротермалитов в черных сланцах, такие как медь, цинк, свинец, содержатся обычно в небольших количествах, но локально, в флюидоактивных зонах тектонических нарушений, их содержание резко возрастает. Группа элементов, типоморфных спутников золота мышьяк, висмут, сурьма, в неизмененных сланцах проявлена слабо, концентрируясь в участках наложенной гидротермальной проработки. Установлена значительная возмущающая роль магния в сланцах. Все это говорит о своеобразии черносланцевых отложений и значительном влиянии ультраосновного материала на их петрохимические особенности. Петрохимические модули указывают на установленную невысокую проявленность процессов механической дифференциации, низкую степень вклада процессов химического выветривания и низкий уровень показателя зрелости материала пород области сноса при формировании основной массы отложений. Площадное и точечное опробование черных сланцев на благородные металлы показало повсеместное присутствие золота, платины и палладия в аномальном количестве в сумме трех металлов не менее 1 г/т. Изложенный материал впервые однозначно указывает на ультрабазиты в качестве единого первичного источника благородных металлов в черносланцевом комплексе. Показано, что благородные металлы (Au, Pt, Pd) сингенетичны вмещающим осадочным терригенным толщам и отлагаются в процессе седиментогенеза. Анализ рудоносности черных сланцев Кавказа и установление древнейшего источника благородных металлов стали отправным пунктом для создания авторами металлометрической геологогенетической модели благородных металлов Северного Кавказа, охватывающей весь фанерозойский этап его развития. Черносланцевая зона Северного Кавказа может рассматриваться как новая перспективная провинция благородных металлов Au, Pt, Pd. The objects of the study are terrigenous rocks that are part of the Tokhan complex (Tokhan cover), located within the Advanced ridge of the North Caucasus and traced for more than 200 kilometers. The Tokhan complex is composed of pelitomorphic carbonaceous sediments (black shales) with subordinate manifestations of volcanogenic, claysiliceous, claycarbonate and psammitic rocks, has experienced greenstone metamorphism. The aim of the work was to analyze the geochemical features of the carbonaceous black shale Hercynian strata of the North Caucasus. Specific for black shale is a complex of elements typomorphic to ultramafic rocks: chromium, cobalt, nickel, titanium, manganese, vanadium, phosphorus. Chalcophilic elements of hydrothermalites in black shales, such as copper, zinc, lead, are usually contained in small quantities, but locally, in fluidactive zones of tectonic disturbances, their content increases sharply. A group of elements, typomorphic satellites of gold arsenic, bismuth, antimony, in unmodified shales is weakly manifested, concentrating in the areas of superimposed hydrothermal development. A significant perturbing role of magnesium in shale has been established. All this indicates the originality of black shale deposits and the significant influence of ultrabasic material on their petrochemical characteristics. Petrochemical modules indicate the established low manifestation of mechanical differentiation processes, a low degree of contribution of chemical weathering processes and a low level of maturity of the material in the drift area during the formation of the bulk of the deposits. Areal and point testing of black shale for noble metals showed the ubiquitous presence of gold, platinum and palladium in abnormal amounts in the sum of three metalsnot less than 1 g / t.The presented material for the first time clearly indicates ultrabasites as a single primary source of precious metals in the black shale complex. It is shown that noble metals (Au, Pt, Pd) are syngenetic to the host sedimentary terrigenous strata and are deposited during sedimentogenesis. Analysis of the orebearing black shales of the Caucasus and the establishment of the oldest source of precious metals became the starting point for the creation of the authors metallogenically geologicalgenetic models of noble metals in the North Caucasus spanning the entire Phanerozoic stage of its development. The black shale zone of the North Caucasus can be considered as a new promising province of precious metalsAu, Pt, Pd.


2020 ◽  
Vol 10 (9) ◽  
pp. 3042
Author(s):  
Joudia Akil ◽  
Stéphane Siffert ◽  
Pirault-Roy Laurence ◽  
Damien P. Debecker ◽  
François Devred ◽  
...  

Carbon dioxide has become an environmental challenge, where the emissions have reached higher level than can be handled. In this regard, conversion of CO2 to value-added chemicals and thus recycling of CO2 appear a viable option. Prior to valorization, CO2 must be purified. Among several opportunities, oxyfuel combustion is a process in rapid development. However, the gases resulting from this process contain some traces of impurities that can hinder the recovery of CO2 such as NO and CO. This work has, therefore, focused on the study of the NO-CO reaction in an oxidizing medium, using heterogeneous catalytic materials based on various supported noble metals. These materials were extensively characterized by a variety of methods including Brunauer–Emmett–Teller (BET) surface area measurements, hydrogen chemisorption, transmission electron microscopy (TEM) and H2 temperature programmed reduction (H2-TPR). The results obtained show that the catalytic behavior of M/Al2O3 catalysts in CO oxidation and NO reduction with CO in oxidative conditions depends mainly on the nature of the metal. The best result for both reactions is obtained with Pt/Al2O3 catalyst. The Pt nanoparticles in their metallic form (Pt°) as evidenced by TPR could explain the activity.


1964 ◽  
Vol 29 (3) ◽  
pp. 251-NP ◽  
Author(s):  
F. KHALIL ◽  
J. TAUFIC

SUMMARY Seasonal changes in the content of neurosecretory material in the supra-optic and paraventricular nuclei and in the pars nervosa of the desert rodents Jaculus jaculus (Oliv.) and Gerbillus gerbillus (Linn.) were followed and compared with those in the white rat kept under laboratory conditions. From the morphological characteristics it was concluded that neurosecretory activity in the desert rodent is minimal in December; signs of increased activity started in March, and maximal activity was reached in June. A decline of neurosecretory activity started in August and continued through the autumn season. In the laboratory white rat, on the other hand, the neurosecretory system showed low activity the whole year round. The quantity of neurosecretory material in the pars nervosa was less in summer than in winter.


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