Gold Sulfide Research Articles

Bromic acid-thiourea synergistic leaching of sulfide gold ore

Abstract Bromate–thiourea coordinated leaching of gold sulfide ore for gold sulfide ore as leaching object. The effects of leaching reagent, stirring speed, and leaching time on gold leaching were investigated in this article. The results showed that the optimum leaching conditions were potassium bromate 0.1 M, thiourea 0.6 g·L−1, hydrochloric acid 0.2 M, agitation speed 250 rpm, ratio of liquid to solid 4, and leaching time 10 min. Under these conditions, high efficiency and rapid leaching of gold can be achieved, and reagent consumption is reduced. The research results have theoretical and practical significance for expanding new green gold extraction technology.

Petrogenesis and tectonic evolution of mineralized mafic intrusions in the Eastern Desert of Egypt: Implications for gold–sulfide genesis

The whole–rock chemistry, mineral chemistry, and remote sensing data of the Atud–UmKhasila Neoproterozoic mafic intrusions in the Eastern Desert of Egypt show two different mafic plutons: (1) the metagabbro–diorite complex; and (2) the G. Atud gabbros. Both of these contain two types of Cu–Ni–Fe–sulfide mineralizations. Multispectral remotely sensed images of Landsat 8 OLI/TIRS, Sentinel 2–B, and ASTER1T were used to give an overview of hydrothermal alteration signatures and distinguish different lithological units. The G. Atud gabbros are intruded into the metagabbro–diorite complex and consist mainly of olivine gabbros, while the metagabbro–diorite complex comprises metagabbros, diorites, and quartz diorites. They were formed under high fO2 (ΔFMQ= +1.43 to + 0.33) with a higher crystallization temperature (∼ 900–1100 °C) and pressure (∼ 6.0 kbar on average) at 18 km depth relative to associated metagabbros. Like magmatic sulfides in mafic intrusions, the G. Atud gabbros contain disseminated grains of pyrrhotite, pentlandite, chalcopyrite, and pyrite, up to 5 vol%. On the other hand, sulfide deposits (up to 30 vol%) such as pyrite, As–bearing pyrite, arsenopyrite, and gold with minor sphalerite and galena at the Atud gold mine, are related to the metagabbro–diorite intrusion. They are found as disseminations, patches, microveinlets, and bands. The sulfide deposits and economic gold are spatially concentrated in smoky quartz veins (up to 25 g/t) and metasomatic alteration zones, i.e., silicification and hematization of metagabbros (0.32 g/t), phyllic, argillic, and propylitic alteration, and carbonate–silicified zones, along gabbroic intrusive contacts, which all follow the Najd NW–SE shear zone. They are possibly of hydrothermal origin (epigenetic). They are also precipitated by mineralized fluids (rich in Si, K, Fe, Pb, Ag, Au, As, S, Ni, Zn, Cu, CO2, and H2O) that have been derived from a mixed magmatic–metamorphic source. The high Au contents with As–bearing pyrite and arsenopyrite in both Fe–rich and smoky quartz veins are related to the interaction between Fe from metagabbro–diorites and the Au(HS)-2 compound as well as the crystallization of pyrite, which reduced the sulfur contents in the mineralized fluids and hence led to gold precipitation. The late intrusion of G. Atud gabbros into metagabbro–diorite rocks enhanced the circulation of sulfide-gold-bearing hydrothermal fluids towards the contacts of the latter ones. These fluids along the shear zones cause metasomatic alteration in addition to leaching and the collection of sulfides and gold in the metagabbros. The protoliths of metagabbro–diorite rocks have a calc–alkaline nature and were formed in a volcanic arc setting, while the G. Atud gabbros were crystallized from Mg-rich tholeiitic melts in the extensional rift (e.g., rifted arc) setting as a result of asthenospheric upwelling due to the slab detachment and/or lithospheric delamination. The Atud gold–sulfide mineralization was related to the thermal uplifting–extensional tectonism. The enrichment of the G. Atud gabbros in LILE, alongside LREE over HFSE, reflects their derivation from a metasomatized mantle source during a rifted arc following the subduction processes.

Orogenic Gold Deposits of Northern Transbaikalia, Russia: Geology, Age, Sources, and Genesis

The paper presents newly obtained and summarizes preexisting data of long-term geochronological and isotope studies of orogenic mesothermal gold deposits in the world’s largest Lena metallogenic province and reviews interpretations of their genesis. Geochronologic data indicate that the gold mineralization was formed during three ore-forming Paleozoic events. The early Late Ordovician–Early Silurian (450–430 Ma) event produced the abundant veinlet—disseminated gold–sulfide mineralization in Neoproterozoic carbonaceous terrigenous–carbonate rocks of the Baikal–Patom foldbelt (BPB). The mineralization was formed simultaneously with regional metamorphic processes. The rejuvenation of hydrothermal activity in the BPB resulted in gold-bearing quartz veins, which was produced in the Middle Carboniferous (340–330 Ma) in relation to postcollisional granitoid magmatism. The latest ore-forming event occurred in the Early Permian (290–280 Ma) and affected exclusively in Precambrian structures of the Baikal-Muya foldbelt (BMB). It was synchronous with the development of intraplate alkaline and subalkaline magmatism in the region. Newly obtained and preexisting isotopic-geochemical (87Sr/86Sr, 143Nd/144Nd, Pb–Pb, and δ34S) data indicate that the mesothermal ore-forming systems of northern Transbaikalia were heterogeneous in their isotopic characteristics, which distinguishes them from the ore–magmatic (intrusion-related type) systems. Comparison of the Sr, Nd, and Pb isotopic composition of the ores and rocks, including magmatic rocks coeval with the gold mineralization, indicates that the Precambrian continental crust was the dominant source of mineral-forming components for the hydrothermal systems of the gold deposits. The contribution of the magmatic source to the genesis of the orogenic gold mineralization was limited and is identifiable only for the Early Permian ore-forming systems of the BMB, for which the input of metals from alkaline mafic melts was suggested.

GOLD ENRICHMENT MECHANISM IN MID-OCEAN RIDGE HYDROTHERMAL SYSTEMS: AN EXAMPLE FROM THE LONGQI HYDROTHERMAL FIELD ON THE ULTRASLOW-SPREADING SOUTHWEST INDIAN RIDGE

Abstract In mid-ocean ridge (MOR) hydrothermal systems, the gold grade of sea-floor massive sulfides (SMSs) is negatively correlated with the spreading rate of the ridge. Previous investigations have addressed the distribution of gold in sulfides from hydrothermal fields hosted by ultramafic rocks. In contrast, the gold enrichment mechanisms in sulfides from hydrothermal fields hosted by mafic rocks in ultraslow-spreading ridge environments are less well constrained. The basalt-hosted Longqi hydrothermal field, located on the classic ultraslow-spreading Southwest Indian Ridge, provides an opportunity to examine gold enrichment mechanisms in such an environment. Two ore-forming stages are identified in chimney fragments: anhydrite + barite + colloidal/porous pyrite (Py1) + marcasite + fine-grained sphalerite (stage 1); euhedral-subhedral pyrite (Py2) + coarse-grained sphalerite + chalcopyrite + isocubanite (stage 2). Py1 is usually overgrown by marcasite, which is in turn enclosed by Py2. Py2 coexists with coarse-grained sphalerite and chalcopyrite. Abundant native gold nanoparticles occur in Py1 or at the transition zone between Py1 and Py2. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis suggests that Py1 contains higher Mo, V, Sn, and Pb and lower As, Co/Ni, and Se/Tl values compared to Py2. In situ LA-multicollector (MC)-ICP-MS analyses show that Py1 has a higher mean δ34S (+7.1‰) value than Py2 (+6.6‰). Sulfur primarily derives from MORB and seawater sulfate, of which the proportion of sulfur from seawater sulfate is between 20.5 and 47.6%. Textures, mineral assemblages, and trace element contents of sulfides indicate that the degree of mixing between hydrothermal fluids and seawater decreases as the chimney grows and is accompanied by a gradual increase in temperature. Based on data compiled from 41 hydrothermal fields hosted by basalt, the large range of sulfide δ34S from slow- and ultraslow-spreading MORs may be attributed to the wide range of sulfur sources (e.g., leaching from MOR basalt, thermochemical reduction of seawater sulfate, magma degassing, and bacterial activity), fluid-basalt interaction, and redox state (CH4/CO2 ratios). Prolonged fluid-basalt interaction and the type of chimneys, such as beehive chimneys, may lead to higher gold grades in hydrothermal fields. Moreover, low H2S content may be an important contributor to gold enrichment in basalt-hosted SMS deposits in ultraslow-spreading MOR environments.

PEGylated Opto-Magnetic Gold and Silver Sulfide Iron Oxide Nanoprobes for Synergistic Photothermal Therapy

PEGylated Opto-Magnetic Gold and Silver Sulfide Iron Oxide Nanoprobes for Synergistic Photothermal Therapy

Remnant Copper Cation-Assisted Atom Mixing in Multicomponent Nanoparticles.

Nanostructured high-/medium-entropy compounds have emerged as important catalytic materials for energy conversion technologies, but complex thermodynamic relationships involved with the element mixing enthalpy have been a considerable roadblock to the formation of stable single-phase structures. Cation exchange reactions (CERs), in particular with copper sulfide templates, have been extensively investigated for the synthesis of multicomponent heteronanoparticles with unconventional structural features. Because copper cations within the host copper sulfide templates are stoichiometrically released with incoming foreign cations in CERs to maintain the overall charge balance, the complete absence of Cu cations in the nanocrystals after initial CERs would mean that further compositional variation would not be possible by subsequent CERs. Herin, we successfully retained a portion of Cu cations within the silver sulfide (Ag2S) and gold sulfide (Au2S) phases of Janus Cu2-xS-M2S (M = Ag, Au) nanocrystals after the CERs, by partially suppressing the transformation of the anion sublattice that inevitably occurs during the introduction of external cations. Interestingly, the subsequent CERs on Janus Cu1.81S-M2S (M = Ag, Au), by utilizing the remnant Cu cations, allowed the construction of Janus Cu1.81S-AgxAuyS, which preserved the initial heterointerface. The synthetic strategy described in this work to suppress the complete removal of the Cu cation from the template could fabricate the CER-driven heterostructures with greatly diversified compositions, which exhibit unusual optical and catalytic properties.

Characterization and prediction of acid mine drainage potential and metal solubility: Critical data for tailings and waste rock management in high sulfidation gold deposits

Abstract In the Purnama gold deposit at the Martabe mine of South Tapanuli District, North Sumatra Province, Indonesia, gold is extracted from the ore and the remaining fine-sized material is stored in the tailings storage facility (TSF) and waste rocks are placed as TSF embankments. Without proper management, tailings and waste rocks from mining can create acid mine drainage (AMD) and release toxic chemicals, posing significant risks to local ecosystems and residents in mining areas. To address this, a mineralogical and geochemical characterization study was investigated, as well as the leaching behavior of heavy metals in the tailings leach column tests (LCT) was conducted. Geochemical characterization showed quartz hornblende andesite and hornblende dacite as NAF materials; clay breccia, volcanic andesite, carbonaceous clay, volcanic breccia, and silica breccia as PAF materials. Further tests revealed that volcanic breccia, carbon clay, and volcanic andesite were classified as high-risk PAF materials, supported by XRD test results. Finally, the LCT results showed that volcanic breccia produced rapid acid drainage, with arsenic (45.9 mg L−1), copper (41.4 mg L−1), and manganese (14.1 mg L−1) being the main dissolved metals. It is important to manage PAF rocks and ensure the water leachate does not contain high concentrations of these metals.

Platinoids in gold sulphide deposits in black shales in the east of the Orenburg Region

Platinoids in gold sulphide deposits in black shales in the east of the Orenburg Region

Gold occurrence and mineralization in the Paleozoic Heijianshan Fe–Cu (–Au) deposit, Eastern Tianshan

Gold (e.g., electrum) has been reported in the Paleozoic Heijianshan Fe–Cu (–Au) or iron oxide–copper–gold-like (IOCG-like) deposit in the Eastern Tianshan, but relationships between gold occurrence and sulfides are unclear. The Heijianshan Fe–Cu (–Au) (or IOCG-like) deposit underwent five alteration and mineralization stages: Pre-ore epidote alteration (Stage I), syn-ore magnetite/iron mineralization (Stage II) followed by pyrite alteration (Stage III) and Cu (–Au) mineralization (Stage IV), and post-ore late veins (Stage V). This deposit mainly has two types of pyrite (A and B) based on pyrite–hematite and pyrite–pyrrhotite–chalcopyrite assemblages. They are euhedral to subhedral and mainly homogenous, with the former having porous or inclusion-rich domains. Trace elements incorporating into pyrite at Heijianshan are mainly controlled by compositions (e.g., As, Co, and Cu), temperature (e.g., Ni and Se), and oxygen fugacity (fO2; e.g., As and Se) of hydrothermal fluids, respectively. The time-resolved depth-concentration profiles suggest trace elements in pyrite and chalcopyrite occur as solid solution (e.g., Co, Ni, Zn, As, and Se) and micro- to nano-sized mineral inclusions (e.g., Cu, Bi, and Pb). The gold occurrence at Heijianshan is invisible as solid solution in Stage III pyrite and Stage IV chalcopyrite and visible as micron-sized Stage IV electrum. Moreover, incorporation mechanisms of invisible gold are Au3+ substituting iron or copper in pyrite A and chalcopyrite, respectively, and Au+ incorporating into the vacancy or defect positions of pyrite B. Sulfides texture and geochemical compositions when combined with previous in-situ sulfur isotope suggest that pyrite formation was resulted from interaction between external basinal brines and altered host rocks under different temperature and fO2 conditions. Ongoing fluid-rock reaction led to formation of chalcopyrite ± electrum veins as Cu (–Au) mineralization at Heijianshan. This study suggests that the prolonged interaction contributes to sulfide formation and Cu (–Au) mineralization in these Paleozoic Fe–Cu or IOCG-like deposits formed in basin-related setting, and the Aqishan-Yamansu belt, Eastern Tianshan has gold mineralization potential.

Fluid inclusions in quartz of the gold-ore occurrences and gold-quartz intergrowths from placers in the Sololi uplift of the Olenyok arch (Yakutia)

Fluid inclusions have been studied in vein quartz with gold sulfide mineralization from metamorphosed sandstones of the Eekite series and metarhyolites of the Early Proterozoic, in quartz breccia from the zone of overlapping gold mineralization on the Early and Middle Permian sandstones, as well as in the gold quartz intergrowths from the Sololi River placer. It has been revealed that formation of quartz breccias occurred within a wide temperature interval from 230 to 425 ºC, with predominance of carbon dioxide and nitrogen in the vapor phase. It is suggested that the increased nitrogen content may be associated with a chemical reaction between the fluid and ammonium-containing silicates of host rocks, in which nitrogen in the form of NH4+ isomorphically replaces potassium at the regressive stage of metamorphism. At the same time, it is possible that mantle nitrogen, which was transported along the Anabar-Eekite deep fault, participated in formation of the studied breccias. The close homogenization temperatures and similar nature of the water-salt composition for the fluid inclusions of quartz veins that inject the Eekite series meta-rocks and meta-rhyolites indicate the synchronism of their formation and attribute them to the common stage of ore formation. Quartz veins with gold sulfide mineralization were the primary sources of pebbles with gold-quartz intergrowths from the Sololi River, this is evidenced by similarity of principal characteristics of fluid inclusions. Oxidizing conditions of the mineralization serve as favorable factor for the Au deposition, it is indicated by the predominant CO2 content in fluid inclusions, keeping role of a geochemical barrier and leading to an elevated gold content in quartz veins.

Conditions of Formation of the Pavlik Gold–Sulfide–Quartz Deposit (Northeast of Russia) According to a Study of Fluid Inclusions

The stockwork gold–sulfide–quartz ores of the Pavlik deposit (northeast of Russia) are formed mainly by homogeneous, low saline (9.4–4.3 wt %-eq. NaCl), essentially water–chloride fluid at temperatures of 275–330°C and a fluid pressure of 600–1840 bar. The fluid is characterized by a rather high CO2 content and a reduced methane content, with the ratio of CO2 : CH4 being 17–37.3. In the fluid, among the cations, the main role is played by Na and Ca, and K and Mg are in a subordinate amount. In addition, many trace elements were detected in the fluid composition: As, Li, Rb, Cs, Mo, Ag, Sb, Cu, Zn, Cd, Pb, U, Ga, Ge, Ti, Mn, Fe, Co, Ni, V, Cr, Y, Zr, Sn, Ba, W, Au, Hg, and rare-earth elements. The obtained data allow us to suppose that there was a decrease in the depth of ore formation during the formation of the deposit by 4–5 km due to the rise of the ore-bearing block. Attention is drawn to the low fluid pressures for a number of samples (330–140 bar), which may be associated with a separate stage of mineral formation. The ore-forming fluid of the Pavlik deposit in composition, temperatures and pressures shows similarities with the fluids of the neighboring Natalka and Rodionovsky deposits and has a great similarity with typical fluids of orogenic gold deposits. The information given in the article is of great practical importance for regional predictive metallogenic constructions, as well as prospecting and evaluation of gold deposits.

Acidithiobacillus ferrooxidans Leaching of Silica-Sulfide Gold Ores from May-Hibey Deposits, Tigray, Ethiopia

Oxidative leaching is an inexpensive alternative to using chemical cyanide extraction methods for gold from low-grade gold sulfide. Oxidation of finely ground gold-bearing ore by Acidithiobacillus ferrooxidans was evaluated in terms of cell density, pH, and leaching efficiency of Fe and Au in shake flask experiments. The compositional and elemental analyses of the beneficiated ore were analyzed using XRD and EDXRF spectroscopy. The ore’s primary constituents are gold (4.356 mg/L), silicon, iron, and sulfur (62.456, 15.441, and 7.912 wt%, respectively). XRD spectra, the main phases of the concentrated ore, showed that the major components of the ore were quartz, syn, silicon sulfide, pyrite, and polymetallic elements such as silderenrite, gismondine, siderenikite, hematite, and syn. The experimental results, with Acidithiobacillus ferrooxidans bacteria and blank, were evaluated. The pH of the blank remained nearly constant, and the pH of the bioleached was occasionally lowered. The A. ferrooxidans strain always grew better throughout the bioleaching process. For the A. ferrooxidans strain, the cell density of cells reached a maximum of 90.00 × 106 cells/mL after the 11th week and decreased to 87.00 × 106 cells/mL after the 12th week. The decrease in cell density may be due to the presence of polymetallic elements such as Al, Cr, Ti, and Ni, leading to reduced metal tolerance of the A. ferrooxidans strain. In the A. ferrooxidans leaching process, the maximum total iron and gold extraction reached 92.16% (14.23 mg/L) and 99.97% (4.355 ppm), respectively, after the 11th week, and leaching tends to decrease up to 14 weeks, which may be due to the formation of secondary minerals. More research will be performed to optimize the procedure and leaching kinetic, examine the impact of metal content, and take into account the potential for bioleaching process pollution in addition to the amount of gold recovered.

Evaluating the catalytic effect of pyrite on thiourea leaching of gold in the absence and presence of citrate

With the depletion of high-quality ore, the extraction of gold from refractory gold ores/concentrates is a promising endeavor. Pyrite is an important gold-bearing sulfide mineral. It is of great significance to study its influence on gold leaching to realize the maximum utilization of refractory sulfide gold ores/concentrates. In this paper, the effect of pyrite on thiourea leaching of gold was investigated through leaching experiment, surface characterization and density functional theory (DFT) calculation. Results showed that the presence of pyrite sharply decreased both gold dissolution and thiourea stability, and its adverse effect of pyrite is likely that pyrite catalyzes the oxidation of thiourea by Fe3+, resulting in the high thiourea consumption, which deteriorates the gold dissolution. The catalytic mechanism is believed to be that thiourea firstly adsorbs on the pyrite surface, and then electrons transfer from thiourea to the oxidant of Fe3+ through the conduction band of pyrite. Citrate was used as an additive to improve the thiourea stability and gold dissolution, and its mechanism was proposed as follows: citrate weakens the interaction between Fe3+ and thiourea by complexing with Fe3+, and competes with thiourea to adsorb on the surface of pyrite, reducing the adsorption of thiourea. Furthermore, the formation of Fe-citrate complexes, as terminal electron acceptor, has a lower oxidation capacity than Fe3+, thus relieving the catalytic effect of pyrite on thiourea oxidation by Fe3+.

The Effect of Aloe Vera Bioreagent as a Frother and Collector in the Gold Ore Flotation Process on Increasing Grade and Recovery

One of the concentration processes in processing sulfide gold ore is the flotation technique which takes advantage of differences in mineral surface properties by adding chemical reagents. The addition of chemical reagents to the flotation process can cause environmental problems. Therefore, efforts are needed to replace chemical reagents with more environmentally friendly materials. In this research, an attempt was made to replace chemical reagents with a commonly found plant extract, namely aloe vera, as a bioreagent. Bioflotation experiments on a laboratory scale were carried out using a Denver flotation cell with an aloe vera reagent as a frother. This gold mineral bioflotation experiment was carried out on a 150 mesh size fraction. The results of increasing concentrate levels by flotation indicate that the aloe vera reagent as a frother is able to produce biosurfactants which replace chemical reagents as a more environmentally friendly biofrother and biocollector. This can be concluded based on flotation experiment data with bioreagent which has been tested showing an Au content value of 10.09 and a recovery of 96.15%, while flotation using chemical reagents shows an Au content value of 10.50 and a recovery of 95.96%. So the use of aloe vera as an environmentally friendly bioreagent in the flotation process releasing low sulfidation gold is more effective than the use of chemical reagents because it is indicated that there is a biosurfactant content in aloe vera.

Mineralogy and Geochemistry of the Mupane and Shashe Gold Deposits of the Tati Greenstone Belt (NE Botswana): Implications for Mineral Deposit Models and Exploration

Abstract The Archean Tati greenstone belt is located at the southwestern margin of the Zimbabwe craton (northeast Botswana) and hosts numerous Cu-Ni ± platinum group element (PGE) and Au ± Ag occurrences and deposits. Gold occurrences/deposits are poorly studied, and key questions pertaining to their genesis remain unclear, including the mode of occurrence(s) of gold, the relative timing of gold introduction with respect to the evolution of the greenstone belt, the number of gold mineralization events, the alteration patterns, and the relationships between each alteration pattern and gold mineralization. A detailed study that includes sulfide and gold grain chemistry using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and electron probe microanalysis (EPMA), respectively, and X-ray diffraction (XRD) of mineralized rock samples of three Tati greenstone belt gold deposits was carried out to constrain the genesis of gold mineralization and formulate exploration guidelines in the Tati greenstone belt. Gold in the Tati greenstone belt is the result of multiple events, is mainly associated with arsenopyrite, pyrite, and sphalerite, and occurs as (1) microinclusions within sulfides, (2) intergrowth with sulfides, (3) minute particles (<2–10 µm) within the silicate matrix, (4) microfractures and microvug infills, and (5) lattice-bound and sulfide-hosted refractory gold. The first gold event (as electrum) is premetamorphic and associated with sphalerite-quartz veins. The second stage is a postmetamorphic high-grade gold event that is accompanied by extensive carbonatization and propylitization of host rocks. The third stage of gold mineralization is marked by the dissolution of gold in the early formed stages 1 to 2 and subsequent reprecipitation within cracks, fractures, and vugs. Auriferous pyrite composition suggests that Au-bearing mineralizing fluids are predominantly of magmatic origin and that their physicochemical compositions changed during the mineralization process, as supported by chemically zoned Au-bearing arsenopyrite, various alteration types containing gold, and variation in gold fineness across the several gold deposits in the Tati greenstone belt. Gold deposition in the Tati greenstone belt mainly occurred through sulfidation, as indicated by the closest spatial association between gold and Fe-bearing sulfides and ferromagnesian silicates. Gold in the Tati greenstone belt is closely correlated with As, Sb, Pb, Bi, Ni, Hg, Tl, Cd, In, Mo, W, Zn, and Te and moderately to weakly associated with Sn, Se, Cr, Co, Ge, Cd, Mn, V, Ga, and Ag. The correlation between Au and fluid mobile elements, i.e., Te, Sb, Se, As, Hg, and Bi, can be used as a vectoring tool during the exploration of gold within the Tati greenstone belt, as these elements likely form halos that are much broader than the primary footprint of gold mineralization.

Thiourea leaching of gold: Elucidating the mechanism of arsenopyrite catalyzed thiourea oxidation by Fe3+ and the beneficial role of oxalate through experimental and density functional theory (DFT) investigations

The combination of bio-oxidation pretreatment of refractory sulfide gold ore and thiourea leaching is a suitable method for gold extraction due to its environmental friendliness and compatibility in the two leaching systems. Arsenopyrite is an important auriferous sulfide mineral where the encapsulated gold can be effectively exposed by bioleaching pretreatment. The issue of high thiourea (TU) consumption, however, severely hinders the commercial application of this technology. In this paper, the effect of arsenopyrite on gold leaching in an acidic TU solution was investigated. Leaching results showed that the presence of arsenopyrite seriously impeded TU leaching of gold represented as the much decrease in gold dissolution and TU stability. The dominant cause for the detrimental effect of arsenopyrite was that arsenopyrite can catalyze the oxidation of TU by Fe3+ and thus bring about high TU consumption, further resulting in the marked deterioration of TU dissolution of gold. The catalytic mechanism is believed to be that TU adsorbs on arsenopyrite surface and then electrons transfer from TU to the oxidant Fe3+ through the conduction bands of arsenopyrite. Oxalate was used to improve TU stability and gold dissolution, and its mechanism was proposed as follows: oxalate not only weakened the interaction between Fe3+ and TU through complexing with Fe3+ but also competed with TU to absorb on the arsenopyrite surface, which decreased the TU adsorption. Besides, the formation of Fe-oxalate complexes, as the terminal electron acceptor, distinctly reduced the oxidation capacity of Fe3+, thus alleviating the catalytic effect of arsenopyrite on TU oxidation by Fe3+.

Морфоструктурные особенности минеральных индивидов в рудах золотосульфидного типа. Забайкальский край

The article deal with the results of a study of the morphostructural features of gold sulfide type ore: the forms of ore mineral deposits, their spatial distribution and relationship. The results of crushed ore research are also reflected. The data obtained make it possible to choose of methods for technological ore processing.

Experimental study on mineral processing of shallow oxidation ore in a hydrothermal metasamatic sulfide gold mine

The ore produced by a gold mine in Fujian province belongs to hydrothermal metasomatism sulfide type gold (silver) ore, and the shallow oxidized ore of the deposit has a gold grade of 0.91g/t. In order to understand the selectability of this oxidized ore, the selectability test study is carried out. Through the beneficiation test study, the concentration of-0.074mm is 70%, the concentration of isoopyl yellow is 150g/t, the concentration of butyl ammonium black is 50g/t, and the concentrate products of 16.98g/t can be obtained, and the gold recovery rate is 74.04%.

МИНЕРАЛОГИЧЕСКИЕ ОСОБЕННОСТИ РУДНЫХ ПРОЯВЛЕНИЙ ЗОЛОТА СОЛОЛИЙСКОГО ПОДНЯТИЯ ОЛЕНЕКСКОГО СВОДА

The paper deals with studied mineralogical and geochemical features of gold-sulphide manifestations of the Sololi uplift of the Olenek arch (northeast of the Siberian Platform) in order to identify their mineralogical features and prospects for their further research. The identical mineral composition of gold-sulphide formations developed by Early Proterozoic rocks of the Eekitian series and rhyolites of the same age gave reason to assume the simultaneity of their formation and to refer them to the general stage of ore formation. According to the established mineral paragenesis, described gold sulphide manifestations are attributed to the gold-quartzsulphide formation type. The discovery of gold sulphide mineralization in the zone of tectonic fracturing of Early-Middle Permian sandstones indicates the formation of ore occurrences in the area associated with the processes of tectonomagmatic activation of the Mesozoic. The identification of indicators of low-temperature hydrothermal processes as mineral paragenesis – mercury-containing gold, cinnabar and barite, testifies to shallow and low-temperature conditions for the formation of this ore manifestation. It was found that according to the Co/Ni ratio, 28% of pyrites (including gold-bearing ones) are associated with hydrothermal processes. In general, the detection of native gold in quartz veins in free form and as microinclusions and impurities in pyrite, as well as the discovery of relatively large poorly rounded attachments of gold to quartz in stream flows dewatering the studied ore formations, allows researchers to positively assess the prospects for further study of ore manifestations of the Sololi uplift of the Olenek arch.

The Regime of the Olimpiada Gold–Sulfide Deposit Formation

The Regime of the Olimpiada Gold–Sulfide Deposit Formation