GOLD EXTRACTION PROCESS FROM SULFIDE ORES AND CONCENTRATES

FIELD: metallurgy, namely gold extraction from sulfide ores and concentrates. SUBSTANCE: method comprises steps of mixing gold- containing sulfide ores and concentrates with calcium-containing additives at content consisting 100 - 120 % of stoichiometrically needed one for complete fixing of sulfur to gypsum; roasting mixture at temperature more than 550°C; using calcium carbonate as calcium-containing additive; extracting gold out of formed roast by flotation. Before flotation it is possible to add to said roast initial concentrate in quantity consisting 1- 5% of roast mass. Invention eliminates SO₂ separation and provides increased by 5 - 8% degree of gold extraction. EFFECT: improved degree of gold extraction. 3 tbl, 3 ex.Изобретение относится к металлургии, в частности к извлечению золота из сульфидных руд и концентратов. Золотосодержащие сульфидные руды и концентраты смешивают с кальцийсодержащими добавками при расходе 100-120% от стехиометрически необходимого для полного связывания серы в гипс и обжигают при температуре выше 550°С. В качестве кальцийсодержащей добавки используют карбонат кальция. Золото из полученного огарка извлекают флотацией. Перед флотацией в огарок можно добавлять исходный концентрат в количестве 1-5% от массы огарка. Техническим результатом является то, что при осуществлении способа исключается выделение SO₂ и обеспечивается повышение извлечения золота на 5-8%. 3 табл

METHOD OF PROCESSING OF SULPHIDE CONCENTRATES

FIELD: metallurgy. SUBSTANCE: method includes mixing of source concentrate with calcium oxide CaO and calcium peroxide CaO₂ and burning in two stages. At the first stage burning is carried out at temperature of 350-500°C within 30-40 minutes, at the second stage - at temperature of 500-800°C during 30-60 minutes. After burning there is performed leaching of non-ferrous metals out of cinder. Consumption of calcium oxide CaO is 50-100% from stoichometric required for binding sulphur into gypsum while consumption of calcium peroxide CaO₂ is 1-10% from concentrate weight. EFFECT: increased extraction of non-ferrous metals and reduced duration of cinder leaching. 2 cl, 2 tbl, 2 ex.Изобретение относится к металлургии цветных металлов, в частности к способам комплексной переработки сульфидных концентратов и промпродуктов, и может быть использовано для извлечения цветных и благородных металлов. Способ включает смешивание исходного концентрата с оксидом кальция СаО и пероксидом кальция СаО₂ и обжиг в два этапа. На первом этапе обжиг ведут при температуре 350-500°С в течение 30-40 минут, на втором - при температуре 500-800°С в течение 30-60 минут. После обжига из огарка ведут выщелачивание цветных металлов. Расход оксида кальция СаО составляет 50-100% от стехиометрически необходимого для связывания серы в гипс, а расход пероксида кальция CaO₂ составляет 1-10% от массы концентрата. Техническим результатом является повышение извлечения цветных металлов и сокращение продолжительности выщелачивания огарка в 1,5-2 раза. 1 з.п. ф-лы, 2 табл

An update of the long-term trend of aerosol optical depth in the polar regions using POLAR-AOD measurements performed during the International Polar Year

An updated set of time series of derived aerosol optical depth (AOD) and Ångström’s exponent a from a number of Arctic and Antarctic stations was analyzed to determine the long-term variations of these two parameters. The Arctic measurements were performed at Ny-Ålesund (1991e2010), Barrow (1977e2010) and some Siberian sites (1981e1991). The data were integrated with Level 2.0 AERONET sun-photometer measurements recorded at Hornsund, Svalbard, and Barrow for recent years, and at Tiksi for the summer 2010. The Antarctic data-set comprises sun-photometer measurements performed at Mirny (1982e2009), Neumayer (1991e2004), and Terra Nova Bay (1987e2005), and at South Pole (1977e2010). Analyses of daily mean AOD were made in the Arctic by (i) adjusting values to eliminate volcanic effects due to the El Chichón, Pinatubo, Kasatochi and Sarychev eruptions, and (ii) selecting the summer background aerosol data from those affected by forest fire smoke. Nearly null values of the long-term variation of summer background AOD were obtained at Ny-Ålesund (1991e2010) and at Barrow (1977e2010). No evidence of important variations in AOD was found when comparing the monthly mean values of AOD measured at Tiksi in summer 2010 with those derived from multi-filter actinometer measurements performed in the late 1980s at some Siberian sites. The long-term variations of seasonal mean AOD for Arctic Haze (AH) conditions and AH episode seasonal frequency were also evaluated, finding that these parameters underwent large fluctuations over the 35-year period at Ny-Ålesund and Barrow, without presenting well- defined long-term variations. A characterization of chemical composition, complex refractive index and single scattering albedo of ground-level aerosol polydispersions in summer and winterespring is also presented, based on results mainly found in the literature. The long-term variation in Antarctic AOD was estimated to be stable, within `0.10% per year, at the three coastal sites, and nearly null at South Pole, where a weak increase was only recently observed, associated with an appreciable decrease in a, plausibly due to the formation of thin stratospheric layers of ageing volcanic particles. The main characteristics of chemical composition, complex refractive index and single scattering albedo of Antarctic aerosols are also presented for coastal particles sampled at Neumayer and Terra Nova Bay, and continental particles at South Pole

Seasonal, interannual and long-term variability of precipitation and snow depth in the region of the Barents and Kara seas

Observation data of temperature, precipitation and snow depth have been compiled and generalized climatologically for a network of 38 stations in and around the Barents and Kara seas, for the period 1951–1992. The monthly precipitation totals were corrected for measuring errors, and the correction method is described in detail. The corrected precipitation values show that the annual precipitation in the region ranges from more than 500 mm along the coast of the Kola Peninsula to less than 200 mm in parts of the north-eastern Kara Sea. The solid fraction of the annual precipitation ranges from 70 % in northern parts to 35 % in southern parts. For the period 1951–1992 the analysis indicates decreasing trends in annual values of temperature, precipitation and snow depths in the north-eastern parts of the region

The Arctic Basin: Results from the Russian Drifting Stations

The authors describe in The Russian North Pole Drifting Stations for the first time the history of establishing drifting stations in the Arctic Basin since 1937. They set out the main aims and goals of the observations made and outline the methods of organizing the drifting stations, gear and equipment for life support and scientific observations at the North Pole drifting stations and during the airborne high-latitudinal expeditions. The main scientific results and the analysis of data obtained during metereological, oceanographic, ice and geophysical observations are presented and the book contains illustrations, maps and tables that can be used by a wide range of specialists investigating the nature of the Arctic region. An analysis of the contribution of the data collected at the drifting stations, the process of envionmental research in the Arctic Basin and the plans for future use of drifting stations is provided, with special emphasis on the forthcoming International Polar Year 2007-2008

Spatial Distribution of Atmospheric Aerosol Physicochemical Characteristics in the Russian Sector of the Arctic Ocean

The results from studies of aerosol in the Arctic atmosphere are presented: the aerosol optical depth (AOD), the concentrations of aerosol and black carbon, as well as the chemical composition of the aerosol. The average aerosol characteristics, measured during nine expeditions (2007–2018) in the Eurasian sector of the Arctic Ocean, had been 0.068 for AOD (0.5 µm); 2.95 cm−3 for particle number concentrations; 32.1 ng/m3 for black carbon mass concentrations. Approximately two–fold decrease of the average characteristics in the eastern direction (from the Barents Sea to Chukchi Sea) is revealed in aerosol spatial distribution. The average aerosol characteristics over the Barents Sea decrease in the northern direction: black carbon concentrations by a factor of 1.5; particle concentrations by a factor of 3.7. These features of the spatial distribution are caused mainly by changes in the content of fine aerosol, namely: by outflows of smokes from forest fires and anthropogenic aerosol. We considered separately the measurements of aerosol characteristics during two expeditions in 2019: in the north of the Barents Sea (April) and along the Northern Sea Route (July–September). In the second expedition the average aerosol characteristics turned out to be larger than multiyear values: AOD reached 0.36, particle concentration up to 8.6 cm−3, and black carbon concentration up to 179 ng/m3. The increased aerosol content was affected by frequent outflows of smoke from forest fires. The main (99%) contribution to the elemental composition of aerosol in the study regions was due to Ca, K, Fe, Zn, Br, Ni, Cu, Mn, and Sr. The spatial distribution of the chemical composition of aerosols was analogous to that of microphysical characteristics. The lowest concentrations of organic and elemental carbon (OC, EC) and of most elements are observed in April in the north of the Barents Sea, and the maximal concentrations in Far East seas and in the south of the Barents Sea. The average contents of carbon in aerosol over seas of the Asian sector of the Arctic Ocean are OC = 629 ng/m3, EC = 47 ng/m3

Spatial Distribution of Aerosol Characteristics over the South Atlantic and Southern Ocean Using Multiyear (2004–2021) Measurements from Russian Antarctic Expeditions

Since 2004, we have carried out yearly measurements of physicochemical aerosol characteristics onboard research vessels at Southern Hemisphere high latitudes (34–72° S; 45° W–110° E). In this work, we statistically generalize the results from multiyear (2004–2021) measurements in this area of the aerosol optical depth (AOD) of the atmosphere, concentrations of aerosol and equivalent black carbon (EBC), as well as the ionic composition of aerosol. A common regularity was that the aerosol characteristics decreased with increasing latitude up to the Antarctic coast, where the aerosol content corresponded to the global background level. Between Africa and Antarctica, AOD decreased from 0.07 to 0.024, the particle volume decreased from 5.5 to 0.55 µm3/cm3, EBC decreased from 68.1 to 17.4 ng/m3, and the summed ion concentration decreased from 24.5 to 2.5 µg/m3. Against the background of the common tendency of the latitude decrease in aerosol characteristics, we discerned a secondary maximum (AOD and ion concentrations) or a plateau (aerosol and EBC concentrations). The obtained spatial distribution of aerosol characteristics qualitatively agreed with the model-based MERRA-2 reanalysis data, but showed quantitative differences: the model AOD values were overestimated (by 0.015, on average); while the EBC concentrations were underestimated (by 21.7 ng/m3). An interesting feature was found in the aerosol spatial distribution in the region of Antarctic islands: at a distance of 300 km from the islands, the concentrations of EBC decreased on average by 29%, while the aerosol content increased by a factor of 2.5

The Changing Face of Arctic Snow Cover: A Synthesis of Observed and Projected Changes

Analysis of in situ and satellite data shows evidence of different regional snow cover responses to the widespread warming and increasing winter precipitation that has characterized the Arctic climate for the past 40-50 years. The largest and most rapid decreases in snow water equivalent (SWE) and snow cover duration (SCD) are observed over maritime regions of the Arctic with the highest precipitation amounts. There is also evidence of marked differences in the response of snow cover between the North American and Eurasian sectors of the Arctic, with the North American sector exhibiting decreases in snow cover and snow depth over the entire period of available in situ observations from around 1950, while widespread decreases in snow cover are not apparent over Eurasia until after around 1980. However, snow depths are increasing in many regions of Eurasia. Warming and more frequent winter thaws are contributing to changes in snow pack structure with important implications for land use and provision of ecosystem services. Projected changes in snow cover from Global Climate Models for the 2050 period indicate increases in maximum SWE of up to 15% over much of the Arctic, with the largest increases (15-30%) over the Siberian sector. In contrast, SCD is projected to decrease by about 10-20% over much of the Arctic, with the smallest decreases over Siberia (<10%) and the largest decreases over Alaska and northern Scandinavia (30-40%) by 2050. These projected changes will have far-reaching consequences for the climate system, human activities, hydrology, and ecology

Multiple Effects of Changes in Arctic Snow Cover

Snow cover plays a major role in the climate, hydrological and ecological systems of the Arctic and other regions through its influence on the surface energy balance (e.g. reflectivity), water balance (e.g. water storage and release), thermal regimes (e.g. insulation), vegetation and trace gas fluxes. Feedbacks to the climate system have global consequences. The livelihoods and well-being of Arctic residents and many services for the wider population depend on snow conditions so changes have important consequences. Already, changing snow conditions, particularly reduced summer soil moisture, winter thaw events and rain-on-snow conditions have negatively affected commercial forestry, reindeer herding, some wild animal populations and vegetation. Reductions in snow cover are also adversely impacting indigenous peoples' access to traditional foods with negative impacts on human health and well-being. However, there are likely to be some benefits from a changing Arctic snow regime such as more even run-off from melting snow that favours hydropower operations