Oxide Ore Research Articles

Influence of Lead Nitrate on Sulfurizing Flotation of a Copper-Cobalt Oxide Ore

Copper-cobalt oxide ores contain several minerals that are economically treatable by concentration techniques. The most used technique is froth flotation in which selective reagents are used to recover more valuables. It is, therefore, important to examine the optimal doses of those reagents while investigating the behaviors of minerals at the same time. This study explored the influence of lead nitrate Pb(NO3)2 on the froth flotation of oxide ore to increase valuable metals recoveries. Four factors were investigated including Pb(NO3)2 dosage, its conditioning, its addition dose in the 2nd fraction, and sulfidiser dosage. Other parameters were kept constant. The optimum was found at 25 g/t of Pb(NO3)2, conditioning together with sodium silicate (Na2SiO3) for 5 min, the addition of 5 g/t of Pb(NO3)2 in the 2nd fraction, and 3,000 g/t of sulfidiser. Recoveries in concentrates were 79.51 % Copper (Cu) and 60.27 % Cobalt (Co), with grades of 9.49 and 0.67 %, respectively. The conclusion was that the use of Pb(NO3)2 can considerably improve copper and cobalt recoveries.

Современное состояние проблемы прогнозирования самовозгорания и взрывчатости сульфидных руд и вмещающих пород на глубине более 1500 м.

The mining factors of ore fire hazard during mining of the lower horizons of the Oktyabrskiy and Talnakhskiy northern deposits are considered. It is noted that the probability of self-heating of sulfide ores and the sulfide dust’s tendency to spontaneous combustion and explosiveness in certain sections of rich sulfide copper-nickel ores are quite high. The oxidation of sulfide ores occurs continuously due to the absorption of oxygen from the mine atmosphere and is accompanied by the release of heat. The oxidation can be accompanied by intense heating of the ore in mining conditions, with the accumulation of large volumes of broken rock mass for a long time in treatment and preparation workings and with free access of air to the bulk of the ore mass. The processes of ore and rock oxidation are especially intense when their moisture content is 1–4%. When the ore is heated above 35 °C, sulfurous gas (SO2) may be released. The main signs of the above-mentioned oxidative processes’ development and signs of the initial phase of a possible underground endogenous fire are indicated along with a constant increase in the temperature of the air coming from the bottom of the face. It is noted that in case of detecting at least one of the signs of a possible underground endogenous fire’s initial phase, urgent measures are taken to improve the ventilation of this working face, to ensure maximum intensity of shipped ore from the fresh stream and the content of sulfurous gas and hydrogen sulfide and mine air temperature are determined every 4 hours. If after two days on the outgoing stream there is no decrease in the content of sulfur dioxide and air temperature, then it should be considered that an endogenous fire has occurred. Measures for the prevention, localization and elimination of foci of spontaneous combustion are given. As an additional safety measure, it is recommended to moisten the dust, since sulfide dust becomes non-explosive at a moisture content of 9–9,5%, and at a humidity of 10% the dust does not transmit an explosive impulse.

Treatment of copper-cobalt alloy with molten magnesium for metal extraction

Cu-Co alloy is an intermediate product from the pyrometallurgical processing of cobalt oxide ores, which mainly contains metallic components of Cu, Co, Fe and Si. This research aims to extract Cu from Cu-Co alloy by selective dissolution using molten Mg. The alloy particles were mixed with Mg and held at temperatures in the range 700–900 °C for 0.5–2 h. The residual Fe-Co-Si alloy settled to the bottom of the melt due to the density difference between the alloy and molten Mg. Under optimal conditions, as much as 99 wt% Cu can be selectively extracted from the alloy by dissolution into the molten Mg. Vacuum distillation at 900 °C was applied to the obtained Mg-Cu alloy, resulting in the formation of Cu power with 80 wt% purity. The recovered Mg metal after distillation could potentially be recycled for re-use. Therefore, this process achieved efficient extraction of Cu without the consumption of Mg and generation of waste, representing an effective and environmentally-sound approach for the processing of Cu-Co alloy.

Leaching kinetics and predictive models for elements extraction from copper oxide ore in sulphuric acid

The results of experimental investigation on the study of leaching kinetics of copper oxide ore in sulphuric acid solution were discussed. The effect of time, pH, stirring speed and temperature on the extend of dissolution was investigated. The XRD analysis indicated that copper is mainly in the form of malachite mineral CuCO3(OH)2. The elemental analysis by XRF showed that the copper oxide ore is composed mainly of 10.07% Cu, 0.71% Co, 4.12% Fe, 24.29% Si, 5.20% Mg, 2.50% Al, 1.00% Ca and 0.48% Mn. Results of dissolution studies showed that the copper oxide ore leaching in H2SO4 solution increase with increasing time, pH, stirring speed and temperature at fixed H2SO4 concentration of 0.77 M. The study showed that 97.02%, 85.41% and 39.64% of copper, cobalt and iron were, respectively, leached by H2SO4 at 70 °C, pH value 1 within 60 min. The important part of this study was to analyse the mechanism and to develop fitting models for leaching process of copper oxide ore by sulphuric acid solution. In understanding the mechanism of dissolution, the reaction rate controlling factor and the order of reaction are of interest. The experimental data were best fitted by mixed controlled mechanism (diffusion and chemical reaction). The corresponding activation energies were calculated to be 24.0 kJ/mol for copper, 28.1 kJ/mol for cobalt and 19.5 kJ/mol for iron. The reaction order was determined to be Gompertz kinetic model. In developing fitting models for the prediction of leaching of copper, cobalt and iron, Eureqa Newtonian software was used. Results confirmed that the suggested models can be effective tools to predict the behaviour and outputs of the dissolution process.

Estimation and Improvement of Recovery of Low Grade Copper Oxide Using Sulfide Activation Flotation Method Based on GA–BPNN

Copper oxide ore is an important copper ore resource. For a certain copper oxide ore in Yunnan, China, experiments have been conducted on the grinding fineness, collector dosage, sodium sulfide dosage, inhibitor dosage, and activator dosage. The results showed that, by controlling the above conditions, better sulfide flotation indices of copper oxide ore are obtained. Additionally, ammonium bicarbonate and ethylenediamine phosphate enhanced the sulfide flotation of copper oxide ore, whereas the combined activator agent exhibited a better performance than either individual activator. In addition, to optimize all of the conditions in a more reasonable way, a combination of the 5-11-1 genetic algorithm and back propagation neural network (GA–BPNN) was used to set up a mathematical optimization model. The results of the back propagation neural network (BPNN) model showed that the R2 value was 0.998, and the results were in accordance with the requirement model. After 4169 iterations, the error in the objective function was 0.001, which met the convergence requirements for the final solution. The genetic algorithm (GA) model was used to optimize the BPNN model. After 100 generations, a copper recovery of 87.62% was achieved under the following conditions: grinding fineness of 0.074 mm, which accounted for 91.7%; collector agent dosage of 487.7 g/t; sodium sulfide dosage of 1157.2 g/t; combined activator agent dosage of 537.8 g/t; inhibitor dosage of 298.9 g/t. Using the combined amine and ammonium salt to enhance the sulfide activation efficiency, a GA–BPNN model was used to achieve the goal of global optimizations of copper oxide ore and good flotation indices were obtained.

From Laboratory towards Industrial Operation: Biomarkers for Acidophilic Metabolic Activity in Bioleaching Systems.

In the actual mining scenario, copper bioleaching, mainly raw mined material known as run-of-mine (ROM) copper bioleaching, is the best alternative for the treatment of marginal resources that are not currently considered part of the profitable reserves because of the cost associated with leading technologies in copper extraction. It is foreseen that bioleaching will play a complementary role in either concentration—as it does in Minera Escondida Ltd. (MEL)—or chloride main leaching plants. In that way, it will be possible to maximize mines with installed solvent-extraction and electrowinning capacities that have not been operative since the depletion of their oxide ores. One of the main obstacles for widening bioleaching technology applications is the lack of knowledge about the key events and the attributes of the technology’s critical events at the industrial level and mainly in ROM copper bioleaching industrial operations. It is relevant to assess the bed environment where the bacteria–mineral interaction occurs to learn about the limiting factors determining the leaching rate. Thus, due to inability to accurately determine in-situ key variables, their indirect assessment was evaluated by quantifying microbial metabolic-associated responses. Several candidate marker genes were selected to represent the predominant components of the microbial community inhabiting the industrial heap and the metabolisms involved in microbial responses to changes in the heap environment that affect the process performance. The microbial community’s predominant components were Acidithiobacillus ferrooxidans, At. thiooxidans, Leptospirillum ferriphilum, and Sulfobacillus sp. Oxygen reduction, CO2 and N2 fixation/uptake, iron and sulfur oxidation, and response to osmotic stress were the metabolisms selected regarding research results previously reported in the system. After that, qPCR primers for each candidate gene were designed and validated. The expression profile of the selected genes vs. environmental key variables in pure cultures, column-leaching tests, and the industrial bioleaching heap was defined. We presented the results obtained from the industrial validation of the marker genes selected for assessing CO2 and N2 availability, osmotic stress response, as well as ferrous iron and sulfur oxidation activity in the bioleaching heap process of MEL. We demonstrated that molecular markers are useful for assessing limiting factors like nutrients and air supply, and the impact of the quality of recycled solutions. We also learned about the attributes of variables like CO2, ammonium, and sulfate levels that affect the industrial ROM-scale operation.

Study of biohydrometallurgical technology used to recover gold from ore at a gold-recovery plant

The article contains the results of the studies performed for the biochemical eхtraction modes for mineral raw materials using thionic bacteria Acidithiobacillusferrooxidans of a certain strain capable to oxidize sulfide minerals. A representative sample of mineral raw materials was taken, and its physical and chemical studies were performed. The optimal conditions to leach mineral raw materials with biochemical solvents based on various factors (temperature, S:W) were established. Modern physical and chemical methods of analysis were used during the study: X-ray fluorescence, X-ray phase, mineralogical, electron probe, chemical analyzes, IR methods to study the phase composition of ores and changes in the structure of minerals. The chemical composition of the ore sample quartered and crushed up to a size of -0.074 mm is as follows, wt. %: SiO2 - 60.11; Al2O3 6.2; Zn 0.016; Cu 0.10; Fe - 2.5; S 0.50; Au - 3.67 g/t and Ag - 3.2 g/t. This paper discusses various options for agitational leaching with acid pre-wash, bacterial dissection and oxidative decomposition of minerals using sodium hypochlorite. The results obtained showed that the most effective method to increase the gold recovery is to perform bacterial oxidation of ore using acidophilic bacteria At. Ferrooxidans preliminarily adapted to the material composition of the test sample, followed by treatment with sodium hypochlorite solution and cyanidation. Biohydrometallurgical ore processing provides high gold recovery (78.1%).

Petrogenesis of the gabbronorite sill hosted Fe-Ti oxide ore bodies from the eastern part of Chotanagpur granite Gneissic Complex, India

Magmatic Fe-Ti oxide ore bodies of the eastern Chotanagpur Granite Gneiss Complex (CGGC), India occur as massive conformable lenses within a gabbronorite sill. The occurrence, lithological association, mineralogy, and geochemistry of the Fe-Ti oxide ore bodies are significantly different from the typical Fe-Ti oxide deposits associated with anorthosite complexes and mafic- ultramafic complexes. Textural evidence and mineral chemistry suggest mostly simultaneous fractional crystallization of the comprising minerals e.g. titanomagnetite, ilmenite and magnesio-hercynite. The temperature and fO2 conditions of re-equilibration are calculated using the compositions of ilmenite and pre-exsolved titanomagnetite pairs. Extrapolation of the data along ulvospinel isopleths reveals the probable original magmatic conditions e.g. temperature ~ 900 °C and fO2 ~ ΔFMQ + 2. The ore forming melt calculated by ‘equilibrium distribution method’ shows no crustal contamination and has a trace elemental pattern similar to typical enriched basaltic melts e.g. ferropicrites, alkali basalts, OIB and EMORB. High Ti and Zr contents of the melt suggest a possible within plate tectonic setting and enrichment in HFSEs and LREEs suggest that the parent melt could be generated from an enriched mantle source by low degree partial melting of garnet-peridotite layer of the upper mantle. The ‘quantitative fractional crystallization modelling’ indicates that early crystallization of olivine, pyroxenes, plagioclase and ilmenite from an enriched basaltic melt similar to EMORB (most fit melt) led to a condition of high oxygen fugacity and iron enrichment in the residual melt. The residual Fe-Ti rich melt moved to low pressure zones within the gabbronorite sill during late stage of D2 deformation, and later crystallized in the form of present ore bodies.

Comparative Cleaning Stages in Recovery of Copper and Cobalt from Tailings using Potassium Amylxanthate as Collector

Copper and cobalt demand is projected to be increased from here to 2050 and the challenge is to find treat economically minerals which contains those metals. Several tailings from oxide ores throughout the word contain good grades of copper and cobalt that should be recovered by froth flotation. This paper investigates the recovery of copper and cobalt through reprocessing of spiral classifier tailings by determination of specific reagents dosage. The flotation behaviours of malachite and heterogenite were studied through many roughing and cleaning flotation tests in order to recovery most of copper and cobalt. The effect of specific reagents was be varied and others parameters were kept constant. The highest recoveries of both copper and cobalt in rougher concentrate were respectively 82.51% and 72.51% with grades of 12.52% and 0.99% respectively. However, the cleaner concentrate was 24.54 Cu% and 1.38% Co with recoveries of 69.26 % and 40.7% respectively. It was concluded that the reprocessing of spiral classifier tailings through froth flotation is benefit because it recovers most of desired metal and reduces the risk of their presence on environment through.

Comparative Cleaning Stages in Recovery of Copper and Cobalt from Tailings using Potassium Amylxanthate as Collector

Copper and cobalt demand is projected to be increased from here to 2050 and the challenge is to find treat economically minerals which contains those metals. Several tailings from oxide ores throughout the word contain good grades of copper and cobalt that should be recovered by froth flotation. This paper investigates the recovery of copper and cobalt through reprocessing of spiral classifier tailings by determination of specific reagents dosage. The flotation behaviours of malachite and heterogenite were studied through many roughing and cleaning flotation tests in order to recovery most of copper and cobalt. The effect of specific reagents was be varied and others parameters were kept constant. The highest recoveries of both copper and cobalt in rougher concentrate were respectively 82.51% and 72.51% with grades of 12.52% and 0.99% respectively. However, the cleaner concentrate was 24.54 Cu% and 1.38% Co with recoveries of 69.26 % and 40.7% respectively. It was concluded that the reprocessing of spiral classifier tailings through froth flotation is benefit because it recovers most of desired metal and reduces the risk of their presence on environment through.

Activation mechanism of lead ions in the flotation of sulfidized azurite with xanthate as collector

Metal ions are commonly used to activate oxide minerals and improve the collector adsorption on the mineral surface. In this work, lead ions were added after azurite was sulfidized with Na2S, and the effect of lead ions on the flotation of sulfidized azurite was investigated. Micro-flotation tests were performed to study the flotation behavior after sulfidized azurite was treated with lead ions, and the activation mechanism was revealed by zeta potential determination, X-ray photoelectron spectroscopy (XPS) analysis, time-of-flight secondary ion mass spectrometry (ToF-SIMS), Fourier-transform infrared (FT-IR) spectroscopy, and ultraviolet spectroscopy measurements. The flotation results showed that the azurite recovery increased when a low concentration of lead ions was poured into the pulp solution in the presence of Na2S. Zeta potential determination indicated that chemisorption occurred when the sulfidized azurite surface was modified with lead ions. The XPS results showed that Pb–S species formed on the sulfidized azurite surface treated with lead ions. ToF-SIMS analysis showed that S−, S2−, SO3−, and Pb2+ ions were present on the azurite surface and the thickness of the S species in the azurite–Na2S–Pb(II) system was larger than in the azurite–Na2S system. FT-IR showed that the interaction between the lead ions and sulfidized azurite surfaces improved the xanthate attachment to the mineral surface. These results illustrated that addition of lead ions after sulfidization of azurite with Na2S was beneficial to the flotation recovery of copper oxide ores containing azurite.

Gold in the Oxidized Ores of the Olympiada Deposit (Eastern Siberia, Russia)

Native gold and its satellite minerals were studied throughout the 300 m section of oxidized ores of the Olympiada deposit (Eastern Siberia, Russia). Three zones are identified in the studied section: Upper Zone ~60 g/t Au; Middle Zone ~3 g/t Au; Lower Zone ~20 g/t Au. Supergene and hypogene native gold have been found in these zones. Supergene gold crystals (~1 μm), their aggregates and their globules (100 nm to 1 μm) predominate in the Upper and less in Middle Zone. Relic hypogene gold particles (flattened, fracture and irregular morphology) are sporadically distributed throughout the section. Spongiform gold occurs in the Lower Zone at the boundary with the bedrock, as well as in the bedrock. This gold formed in the process of oxidation of aurostibite, leaching of impurities and its further dissolution. Hypogene gold is commonly isolated but for supergene gold typically associated with ferric (hydr)oxides. New formation of gold occurred due to oxidation of sulfide ores and release of “invisible” gold, as well as dissolution, mobilization and re-deposition of metallic hypogene gold. A model for the formation of oxidized ores with the participation of meteoric and low-temperature hydrothermal waters has been proposed.

Liquid immiscibility in the Panzhihua intrusion, SW China: Evidence from ore textures and Fe–Ti oxide-rich globules in gabbros

Abstract The Panzhihua intrusion hosts a large Fe–Ti oxide deposit in the Permian Emeishan large igneous province (ELIP), SW China. The mechanism of such massive Fe–Ti oxide accumulation in the layered intrusion is still a matter of debate. In this study, we suggest that the ore formation occurred via density-driven liquid segregation of immiscible Fe-rich liquid, instead of simple mineral sorting of Fe–Ti oxides. Interstitial oxides and kinked plagioclase crystals reveal that the Fe–Ti oxides were crystallized in-situ after their surrounding silicate minerals. Dissolution texture of primocryst plagioclase is ubiquitous in the ores, indicating that the primocryst plagioclase grains were in disequilibrium with the surrounding melt. Fe–Ti oxide-rich globules (~38 wt% FeO) are present in the ore-barren gabbro, and likely represent solidified pockets of the immiscible Fe-rich liquid. Olivine in the Fe–Ti oxide ores occurs as primocrysts (avg. Fo = 68.5) that crystalized before the interstitial Fe–Ti oxides, or as growth rims (avg. Fo = 77.5) that crystalized after interstitial Fe–Ti oxides. The primocryst olivine was likely in equilibrium with the Panzhihua parental magma, and its composition matches well with that of the basalt (Fe2O3T = ~16 wt%) exposed near the intrusion. The olivine rim was likely in equilibrium with the residual melt produced from ~33% crystallization of the Fe–Ti oxide-rich globule. This study confirms that the ore layers are formed by the sinking of dense immiscible Fe-rich liquid to squeeze out the original silicate melt in the crystal mush, forming the (semi-)massive Fe–Ti oxide layered ores.

Geochemistry of Fe-Ti oxide and sulfide minerals in gabbroic rocks and magnetitite of the Archean Mayurbhanj mafic complex (eastern India): Magma fractionation, thermometry and oxygen fugacity of re-equilibration, and implications for Ni-Cu mineralization

The Archean Mayurbhanj mafic complex in the Singhbhum Craton (eastern India) contains a magmatic Fe-Ti-(V) oxide ore deposit within a gabbro-norite-anorthosite suite of rocks. Immediate country rocks belong to the early Archean Gorumahisani greenstone belt and 3.1 Ga granitic complex. The gabbro-noritic rocks of the Mayurbhanj complex consist of plagioclase (An26−69), clinopyroxene (En42−54Fs4−36Wo22−42), and orthopyroxene (En67−81Fs15−28Wo4−5) as cumulus phases with Fe-Ti-oxides (magnetite and ilmenite) and sulfides (pyrite, pyrrhotite, chalcopyrite) as disseminated phases. Two-pyroxene thermometry yields temperatures of 1199 °C − 956 °C which are close to the primary liquidus temperature of pyroxene from a fractionated basaltic magma. The co-existing magnetite and ilmenite pairs in gabbro and magnetitite yield equilibrium temperatures of 498–797 °C and oxygen fugacities of 11.38–27.1 (log fO2) reflecting various stages of cooling and subsolidus re-equilibration of the mineral phases. Disseminated sulfides are mainly present along the grain boundaries of accessory Fe-Ti oxide grains, within interstitial spaces of silicate minerals, as inclusions within the silicate minerals and along altered fracture zones of the silicate host whereas the magnetitite bodies are devoid of such sulfide mineralization. In-situ trace element analysis of oxide and sulfide minerals from the gabbro-noritic rocks and magnetitite ores reveals a higher concentration of Cr (22301–67433 ppm) and Ni (896–3880 ppm) in the magnetite of gabbro than in the magnetitite bodies. This is due to early fractionation of the accessory magnetite in the gabbro from a Fe-rich basaltic magma. The lower concentration of V (30211–34608 ppm) in the accessory magnetite of the gabbro-noritic rocks than in the magnetitite (48534–64855 ppm) suggests partitioning of vanadium into clinopyroxene within the gabbroic rocks. Higher chalcophile element (Pb ≈ 2–11 ppm, Zn ≈ 6773–8139 ppm, Mo ≈ 25–68 ppm) concentrations in magnetite of the gabbro-noritic rocks indicate equilibration with co-magmatic sulfide mineral assemblages. The partitioning behavior of HFSE (Zr, Hf, Ta, Nb) in the magnetite and ilmenite is mainly dependent on the Ti4+ content of the minerals. The rim of iron-oxide minerals around sulfide grains and negative Ni anomaly in the trace element pattern of pyrite suggest that these pyrite grains have formed after pyrrhotite which is magmatic in origin. Enrichment of Pb (≈ 27–3120 ppm), Ag (≈ 8–15 ppm), Bi (≈ 0.2–9 ppm), As (≈ 48–6561 ppm), and Sb (≈ 0.4–18 ppm) in a few pyrites suggests hydrothermal alteration of primary magmatic pyrite grains.

Formation of the Weiya magmatic Fe–Ti oxide deposit and its ore-hosting layered gabbro intrusion, Eastern Tianshan (Xinjiang, NW China)

The Weiya is the largest magmatic Fe–Ti oxide deposit in the Chinese Eastern Tianshan orogen, and is divided into an eastern, central and western section by younger granitoid and diabase intrusions. The Weiya eastern section contain Fe-Ti oxide ores and ore-bearing apatite-poor layered gabbro, which display significant difference in mineral assemblage from the layered gabbro in the central section. We presented new data on the geology, mineralogy, petrology, geochemistry, geochronology, and Sr-Nd isotopes of the gabbroic rocks and the Fe-Ti oxide ores from the eastern section. Igneous zircons from the Weiya anorthosite yielded a SIMS U–Pb concordia age of 237.9 ± 0.71 Ma, coeval with the apatite-rich gabbro in the central section. The gabbroic rocks and Fe-Ti oxide ores in the eastern section and the central section have parallel chondrite-normalized REE patterns and N-MORB-normalized multi-element patterns, together with highly-similar Sr-Nd isotope features, suggesting that the two are comagmatic. Olivine Fo value (62.0–66.7), clinopyroxene Mg# number (68.1–76.2) and plagioclase An contents (39.9–55.4) suggest that the Weiya parental magma was highly evolved after extensive fractional crystallization in the deeper magma chamber, and the residual magma became increasingly oxidized and metals- and volatiles-rich. During the magma emplacement, plagioclase accumulated extensively in the magma chamber roof and further enriched Fe–Ti in the residual melts, leading to Fe–Ti oxide mineralization.

Leaching and solvent extraction purification of zinc from Mehdiabad complex oxide ore

An integrated hydrometallurgical process was used for the zinc leaching and purification from a zinc ore containing 9.75 wt% zinc. The zinc minerals in the ore were hemimorphite, willemite, and calcophanite. Main gangue minerals were quartz, goethite, hematite, and calcite. Central composite design (CCD) method was used to design leaching experiments and the optimum conditions were found as follows: 30% of solid fraction, 22.05% sulphuric acid concentration, and the leaching temperature of 45 °C. The PLS containing 35.07 g/L zinc, 3.16 g/L iron, and 4.58 g/L manganese impurities was produced. A special purification process including Fe precipitation and Zn solvent extraction was implemented. The results showed that after precipitation of iron, Zn extraction of 88.5% was obtained with the 2 stages extraction system composed of 30 vol% D2EHPA as extractant. The overall Zn recovery from the ore was 71.44%. Therefore, an appropriate solution containing 16.6 g/L Zn, 0.05 g/L Fe, and 0.11 g/L Mn was prepared for the electro-winning unit without using the roasting and calcination steps (conventional method), which result in environmental pollution.

Application of hyperspectral remote sensing for supplementary investigation of polymetallic deposits in Huaniushan ore region, northwestern China

A gold–silver–lead–zinc polymetallic ore was selected in Huaniushan, Gansu Province as the study area. Hyperspectral aerial images as the primary information source, ground spectrum tests, and sampling analysis were used as auxiliary techniques. They were combined with large-scale mineral and geological maps and other high-resolution satellite remote sensing images. Hyperspectral remote sensing classification identification and quantitative analysis methods were used to study the main mineral resources and rock mass occurrence. Finally, deposit distribution information was extracted and validated. The results showed that the effective classification methods by hyperspectral images were spectral angle mapping, minimum noise fraction transform, and mixed tuned matched filtering. Based on the ground survey, combined with sampling analysis, the accuracy of classification was 80%. The recognition rate of the main ore body—the iron-manganese cap lead–zinc oxide ore—was as high as 81%. This research showed that hyperspectral remote sensing in this mining area has excellent demonstration effects and is worth completing and supplementing original mineral and geological maps. The targets are important areas for detailed follow-up on mineral resource exploration.

РАЗРАБОТКА ТЕХНОЛОГИЧЕСКИХ РЕКОМЕНДАЦИЙ ПО ОБЕСПЕЧЕНИЮ ПОЖАРОВЗРЫВОБЕЗОПАСНОСТИ ПРИ ПОДЗЕМНОЙ РАЗРАБОТКЕ МЕСТОРОЖДЕНИЙ КОЛЧЕДАННЫХ РУД

The urgency of the problem of reducing the risks associated with spontaneous com-bustion of coal ores and sulfide dust explosions has now increased not only in Russia, but al-so abroad, as there have been significant changes in the mineral resource base of the world's leading metal producers. The oxidation of sulfide ores and rocks with air oxygen is an irre-versible and characteristic exothermic reaction that should be taken into account during the extraction and processing of sulfide-containing minerals to prevent spontaneous combustion of ores and explosions of sulfide dust. The article presents the developed technological measures and recommendations aimed at preventing the processes of oxidation and sponta-neous combustion of coal ores and sulfide dust explosions.

THE MICROWAVE IRRADIATION EFFECT ON THE FLOATABILITY OF MIXED SULPHIDE/OXIDE COPPER ORES

Pre-treatment of copper sulphide and oxide ores using microwave radiation causes a difference in their floatability through change in the surface properties of the minerals. The aim of this study is to investigate the behaviour of Sungun porphyry copper ore under the influence of microwave radiation. In this regard, the feed sample of Sungun copper flotation circuit has been subjected to microwave irradiation for 0-120 s and a radiation power of 0-600 W. The prepared samples were then subjected to flotation experiments. According to the results, the grade of sulphide and oxide Cu minerals, as well as the grade of Fe, increased by microwave irradiation in all experiments compared to the non-irradiated samples. At the same time, recovery rate has a reversed trend and decreased in all cases. Variations in the recovery rates of copper oxides and sulphides due to microwave irradiation are different. Increasing the power of irradiation resulted in a greater reduction in the recovery of copper oxides than of sulphides. On the other hand, increasing the power of microwave irradiation reduced the amount of iron recovery in the copper concentrate and with an increase in the duration of microwave irradiation, the reduction of iron recovery values is even more pronounced. Changes in the power and duration of microwave radiation have not had a significant effect on variations in oxide copper grade in flotation tailings. While the grade of sulphides in tailing is affected by the parameters of microwave irradiation and with an increase in power and duration of microwave irradiation, the grade of copper in tailing increases.

Forms of Gold and Some Typomorphic Characteristics of Native Gold of the Pavlik Orogenic Deposit (Magadan Oblast)

Abstract—The ratios of vein and ore minerals bearing native gold, the shape and size native gold particles, their surface features, variations in chemical composition, and the presence and distribution of impurities and inclusions in them, allow sufficiently substantiated assumptions about ore-forming settings and composition, phase state, and certain other parameters of ore-forming fluids that precipitated native gold. If these data are insufficient for a full-fledged judgment on the ore formation processes, they can at least be used to curtail various genetic speculations. Certain typomorphic features of native gold were studied from one of the largest orogenic gold deposits in northeastern Russia. New data on the grain size distriubtion and chemical composition of native gold and gold contents in sulfides of the Pavlik deposit were obtained. Optical and SEM images were used to determine the ore texture, morphology, and internal structure of native gold and auriferous pyrite and arsenopyrite. ICP-MS, EDS, EDX were used to assess the composition of gold grains, EPMA and LA-ICP-MS were used to qualitatively and quantitatively characterize gold-bearing grains of pyrite and arsenopyrite. It was established that microscopic (finely dispersed (>0.0005–0.01), dusty (>0.01–0.05), extremely fine (>0.05–0.1)) (peak size at 0.075 mm), visible (very fine (>0.1 –0.25)), and fine (>0.25–1.00)) (size peaks at 0.25, 0.55 and 0.85 mm) native gold in association with sphalerite, pyrrhotite, pyrite, arsenopyrite, quartz, carbonates, albite, and sericite is widespread at the Pavlik deposit. Gold particles with an average size of 0.3 mm predominate by weight. Comparison of grain size distribution data with the technological properties of ores and the results of mining in the Omchak ore–placer district made it possible to establish that the share of dusty and fine-dispersed size classes accounts for at least 15–20% of the gold mass at the deposit. ICP-MS analysis of a bulk sample of a monofraction of native gold, which included native gold grains from different parts of the deposit, showed that the composition of the monofraction includes Fe, Hg, As, Zn, Cu, and Pb impurities. The average gold fineness was 806 with additional peaks of 775, 855, and 985 (EPMA determinations). The heterogeneity of native gold is due to the redistribution of silver during late deformation events and, to a lesser extent, removal of silver from gold in the ore oxidation zone. Inclusions in gold are represented by microvoids, disseminated fragments of host metasomatites, and crystals or crystal fragments of potassium feldspar, albite, ankerite–dolomite, and arsenopyrite. The low gold content in pyrite and arsenopyrite, with a high (up to 287 g/t) gold content in arsenic-bearing pyrite and ratios of molar amounts of gold and arsenic in arsenopyrite, may indicate that gold is bound in the crystal structure of sulfides. The relationship between native gold and vein and ore minerals, the features of native gold, and the regularities of gold distribution in pyrite and arsenopyrite do not contradict the hypothesis that native gold was deposited at a single mineralization stage in a different substrate: (1) in the intergranular space (quartz–carbonate metasomatites), (2) in the interstitial space (in arsenopyrite and carbonates), (3) in microfissures in the host minerals. Obviously, the deposition of native gold is an independent process occurring against a background of metamorphogenic (quartz–carbonate veins) and magmatic–metamorphogenic (disseminated pyrite and arsenopyrite) mineralization. Comparison of native gold from ore and placer objects of the Omchak ore–placer district has culminated in methods for using the typomorphic features of native gold to search for placer sources. It seems that various inclusions in native gold with a porous surface are promising for identifying old sources and reconstructing its crystallization conditions.