Activation mechanism of ammonium oxalate with pyrite in the lime system and its response to flotation separation of pyrite from arsenopyrite

The activation properties of ammonium oxalate on the flotation of pyrite and arsenopyrite in the lime system were studied in this work.Single mineral flotation tests showed that the ammonium oxalate strongly activated pyrite in high alkalinity and high Ca^(2+)system,whereas arsenopyrite was almost unaffected.In mineral mixtures tests,the recovery difference between pyrite and arsenopyrite after adding ammonium oxalate is more than 85%.After ammonium oxalate and ethyl xanthate treatment,the hydrophobicity of pyrite increased significantly,and the contact angle increased from 66.62°to 75.15°and then to 81.21°.After ammonium oxalate treatment,the amount of ethyl xanthate adsorption on the pyrite surface significantly increased and was much greater than that on the arsenopyrite surface.Zeta potential measurements showed that after activation by ammonium oxalate,there was a shift in the zeta potential of pyrite to more negative values by adding xanthate.X-ray photoelectron spectroscopy test showed that after ammonium oxalate treatment,the O 1s content on the surface of pyrite decreased from 44.03%to 26.18%,and the S 2p content increased from 14.01%to 27.26%,which confirmed that the ammonium oxalatetreated pyrite surface was more hydrophobic than the untreated surface.Therefore,ammonium oxalate may be used as a selective activator of pyrite in the lime system,which achieves an efficient flotation separation of S-As sulfide ores under high alkalinity and high Ca2+concentration conditions.

Effect of arsenopyrite on thiosulfate leaching of gold

Arsenopyrite was artificially added into the thiosulfate leaching solution to clarify the role of arsenopyrite on the thiosulfate leaching of gold.The effect of arsenopyrite on the thiosulfate leaching of gold was studied by the thermodynamic calculation,mineral dissolution test,leaching test and XPS analysis.The results show that the thiosulfate consumption slightly increases with increasing the concentration of arsenopyrite,but the gold dissolution is obviously hindered.This may mainly attribute to the catalytic effect of arsenopyrite on the thiosulfate decomposition and the formation of passivation layer on the gold foil surface.The passivation layer likely consists of Cu2S or Cu（S2O3）35-,element S,FeOOH and iron arsenate,which is deduced from the XPS analysis.However,the negative effect of arsenopyrite can be eliminated by adding additives.It is found that both additives of sodium carboxymethyl（CMC） and sodium phosphate（SHPP） can not only decrease the thiosulfate consumption but also improve the gold dissolution.

Synthesis of glycerine-xanthate and its depressing mechanism in separation of marmatite from arsenopyrite

A small molecular organic depressor glycerine-xanthate was synthesized. The effect of glycerine-xanthate on the flotation of sulfide minerals was investigated based on a function of pH value and concentration of glycerine-xanthate through flotation experiments in the presence and absence of Cu^2＋. The results show that glycerinee-xanthate has a strong dressing effect on marmatite at pH〉6 and on arsenopyrite in weak acid and base conditions with butyl-xanthate as collector. In the presence of glycerine -xanthate, marmatite is activated by addition of Cu^2＋, but arsenopyrite cannot be activated and remains unfloatable. So the selective separation can be achieved for two minerals. The depression of glycerine-xanthate on sulfide minerals was discussed based on the radical electronegative calculation and the theory of HSAB. Infrared spectrum shows that there are some -OH and-CSS-in glycedne-xanthate molecule, which competes with butyl-xanthate on the mineral surface. As a result of many hydrophilic groups in glycerine-xanthate, the surfaces of marmatite and arsenopyrite become hydrophilic, thus the flotation of marmatite and arsenopyrite is depressed. The collector is adsorbed preferentially on the surface of marmatite and it shows a better floatability in the presence of Cu^2＋, whereas, the surface of arsenopyrite absorbs glycerine-xanthate and the flotation of arsenopyrite is depressed by glycerine-xanthate.

Selective depression mechanism of combination of lime and sodium humate on arsenopyrite in flotation separation of Zn-As bulk concentrate

Lime(CaO)and sodium humate(NaHA)were used as the combined depressant for arsenopyrite pre-treated by CuSO_(4) and butyl xanthate.Micro-flotation tests show that the combined depressant CaO and NaHA achieved the selective depression of arsenopyrite.Closed-circuit lab-scale test results indicate that the synergistic effect of CaO+NaHA achieved a satisfactory flotation separation of sphalerite and arsenopyrite,for which the Zn grade and recovery of Zn concentrate were 51.21%and 92.21%,respectively.Contact angle measurements,adsorption amount measurements and X-ray photoelectron spectroscopy analysis indicate that the dissolved calcium species(mainly as Ca(2+))were adsorbed on the mineral surfaces,thereby promoting NaHA adsorption.Moreover,the surface of the arsenopyrite absorbed more amount of calcium species and NaHA than that of the sphalerite,thereby accounting for the strong hydrophilic surface of arsenopyrite.The adsorption of NaHA on arsenopyrite was mainly chemical adsorption through its carboxyl groups and Ca atoms,whereas that on sphalerite surface was relatively weak.

THE PULP ELECTROCHEMISTRY OF FLOTATION SEPARATION FOR STIBNITE-ARSENOPYRITE BULK CONCENTRATE

In the thermodynamics, for flotation separation of the SbAs bulk concentrate system there is no potential extent using butyl xanthate as collector. However in the kinetics, there exists 150 mV in reducing potential of butyl dixanthogen on the surface of stibnite and arsenopyrite. In this paper, their reducing kinetic difference of electrochemistry was confirmed by pure mineral flotation under controlled potential, the artificial SbAs bulk concentrate flotation separation and UVspectrophotometic analysis. The electrochemical separation of SbAs bulk concentrate has been carried out. qualified concentrate has been obtained. Sbconcentrate contains Sb 4944 %, As 044 %, Sbrecovery is 8783 % and Asconcentrate contains As 1096 %, Asrecovery is 9466 %.

Galvanic effect of magnetite on electrochemical oxidation of arsenopyrite in acidic culture medium

The galvanic interaction of arsenopyrite−magnetite in acidic culture medium was investigated by electrochemical measurements,X-ray photoelectron spectroscopy characterization and leaching experiments.The results indicated that the rest potential of magnetite was 321 mV,which was more anodic than 223 mV of arsenopyrite,and the galvanic current was 7.40μA,verifying the existence of the galvanic interaction between arsenopyrite and magnetite.The galvanic potential and polarization curves suggested that the redox behaviors of arsenopyrite dominated the overall galvanic interaction.The galvanic interaction enhanced the electrochemical dissolution of arsenopyrite with the generation of more oxidation products(S^(0),SO_(3)^(2−),SO_(4)^(2−)and AsO_(3)^(3−)) on arsenopyrite and an increase in the chemical reactivity of the surface.Leaching experiments of 6 days showed that the presence of magnetite improved the arsenic release from arsenopyrite by 30 mg/L,and further confirmed the enhanced oxidation of arsenopyrite when coupled with magnetite.

Effect of the surface microstructure of arsenopyrite on the attachment of Sulfobacillus thermosulfidooxidans in the presence of dissolved As(Ⅲ)

Understanding bacterial adsorption and the evolution of biofilms on arsenopyrite with different surface structures is of great signific-ance to clarifying the mechanism of microbe-mineral interfacial interactions and the production of acidic mine drainage impacting the environ-ment.In this study,the attachment of Sulfobacillus thermosulfidooxidans cells and subsequent biofilm formation on arsenopyrite with different surface structures in the presence of dissolved As(Ⅲ)was studied.Arsenopyrite slices with a specific surface were obtained by electrochemic-al corrosion at 0.26 V.The scanning electronic microscopy-energy dispersion spectra analyses indicated that the arsenopyrite surface deficient in sulfur and iron obtained by electrochemical treatment was not favorable for the initial adsorption of bacteria,and the addition of As(Ⅲ)in-hibited the adsorption of microbial cells.Epifluorescence microscopy showed that the number of cells attaching to the arsenopyrite surface in-creased with time;however,biofilm formation was delayed significantly when As(Ⅲ)was added.

Interaction mechanism of ferrate(Ⅵ) with arsenopyrite surface and its effect on flotation separation of chalcopyrite from arsenopyrite

Potassium ferrate(K_(2)FeO_(4)) was used as a novel environmental-friendly depressant,and its inhibition effect on flotation performance of arsenopyrite and chalcopyrite using potassium ethyl xanthate(PEX)as a collector was investigated by flotation experiments,contact angle measurements,adsorption measurements,localized electrochemical impedance spectroscopy(LEIS)measurements,and X-ray photoelectron spectroscopy(XPS)analyses.The results showed that K_(2)FeO_(4)strongly depressed arsenopyrite in a pH range of 4−11,and the flotation separation of chalcopyrite from arsenopyrite could be realized in the presence of 5×10^(−4)mol/L K_(2)FeO_(4)and 5×10^(−5)mol/L PEX at pH 8 or 10.In the presence of K_(2)FeO_(4) and PEX,the contact angle and the xanthate adsorption capacity of arsenopyrite decreased significantly.LEIS measurements showed that the addition of ferrate could significantly increase the impedance of the arsenopyrite surface.XPS analyses further confirmed that ferrate accelerated the oxidation of arsenopyrite surface.

Analysis of Impurity Density in the Structure of Arsenopyrite of the Panimba Deposit

Based on comprehensive analysis of the crystal structure, chemical and phase composition of natural arsenopyrite of the "Panimba" deposit (Krasnoyarsk region), an analytical expression for calculating the impurity density in structure of minerals type of marcasite are received.

Thermal Decomposition of Pyrite, Arsenopyrite and Auriferous Concentrates in the Presence of Sodium Hydroxide

The thermal decomposition of pyrite, arsenopyrite and auriferous concentrates in the presence of sodium hydroxide was studied by using TG DTA and XRD methods. For the arsenopyrite mineral the reaction takes place at 200～350℃ with the formation of Na 2SO 4, Na 3AsO 4, FeSO 4, Fe 8As 10 O 23 and FeAs, and a large amount of FeAsS do not decompose at this temperature. When the temperature arrives at 800℃, the exothermic reaction takes place with the formation of Na 3AsO 4, Na 2SO 4, Fe 2O 3 and a little amount of As 4S 3. For the pyrite mineral the reaction takes place between 200～350℃ with the formation of Fe 2(SO 4) 3, Fe 3S 4, FeS, Na 2Fe(SO 4) 2 in addition to unreacted FeS 2 and NaOH. When the temperature arrives at 800℃, almost all the pyrite decomposes and the Fe 2O 3, Na 2SO 4, Fe(SO 4) 3 and a minor amount of Fe 1- x S are produced. The decomposition temperatures of arsenopyrite and pyrite get lower as their particle sizes are small. The results also indicated that with the addition of an appropriate amount of NaOH, nearly complete containment of arsenic and sulphur during the decomposition of auriferous concentrate may be possible.

REACTIONS OF ARSENOPYRITE IN CATALYTICAL OXIDATION ACID LEACHING SYSTEM

The kinetics of the catalytical oxidation acid leaching of arsenopyrite is studied in the HNO3-H2SO4-O2 aqueous system. In addition to the effect of reaction time on the extraction of arsenopyrite and distribution of products, the effects of operation factors and several additives on the reaction rate are also investigated. The experi mental results show that the oxidation rate is greatly dependent on nitric acid concentration, average radius of samples and acid concentration. The elemental sulphur produced does not interfere with the progress of the reacation process. It is found that a shrinking core model with chemical reaction controlling, which is expressed as 1-（1-α）1/3=kt, may be adopted to describe the kinetics results. The apparent activation energy is tested to be 23. 6 kJ/mol.

Flotation separation of arsenopyrite from several sulphide minerals with organic depressants

In this paper, the separation of arsenopyrite from chalcopyrite, pyrite, galena with organic depressants （guergum and sodium humic ） was discussed, and the functioning mechanism of those organic depressants was discussed. The experimental results of monomineral flotation indicated that both guergum and sodium humic have depressing effect on arsenopyrite in the presence of ethyl xanthate. Guergum and sodium humic showed different depressing ability to pyrite, chalcopyrite and galena, and the higher the pH value in pulp, the stronger the depressing ability. Ultraviolet-Visible Spectrophotometric study showed that the adsorption layer of xanthate on surface of minerals had been desorhed by the two organic depressants, and the selective desorption of the collector layer was found from different minerals. The xanthate cover on minerals surface was set free when dosage of the organic depressants was high enough. For artificially-mixed minerals, the separation of arsenopyrite from other sulphides was successfully realized by controlling dosage of the organic depressants. And sodium humic had been concentrates in a commercial Lead-Zinc concentrator.

A Prospecting Mineralogy Study: Arsenopyrite In Endogenetic Gold Deposits

Arsenopyrite is one of very important and common auriferous minerals in endogenetic gold deposits. In seven gold deposits, the prospecting typomorphic characteristics of arsenopyrite, such as morphological typomorphism, composition typomorphism, pyroelectricity typomorphism and so on, were established. The crystal form of arsenopyrite is simple, and the form symbols mainly are {101}, {120}, {210}, {140}, {230}, {012}, etc. The smaller grain and poor crystal form arsenopyrite indicates the better auriferous characteristics. The major elements (Fe, As and S) of gold-bearing arsenopyrite usually show Fe/As+S>0.5,As/S<1 which deviates from its theoretical value. The most important trace element is Au and next is Ag in arsenopyrite, and they often show the positive correlation. The pyroelectricity of arsenopyrite can reflect the mineralization epoch, and it also is related to the crystal form and granudarity.

Metallogenesis of the Baidi Au-Sb deposit, southwest Guizhou Province, China: mineralogical and geochemical evidence from sulfur-bearing minerals

The Baidi Au-Sb deposit, which contains 8 t of Au and 10,979 Mt of Sb, is a typical and rare paragenetic deposit located in southwestern Guizhou Province, China.Previous studies have focused on individual ores, but have not combined them to identify their paragenetic mechanism or metallogenic regularity. Therefore, we used field investigations, microscopic observations, and in situ analyses to identify the spatial distribution, mineral paragenesis, compositional evolution, and metallogenic material sources of the ore bodies. We also determined the Au and Sb paragenetic characteristics and the metallogenesis of the deposit. The main Au-bearing minerals in the deposit were early(Apy1–2) and late(Apy3) stage arsenopyrites, as well as pre-mineralization(Py1), mineralization(Py2–5), and late mineralization(Py6–7) stage pyrites. The main Sb-bearing minerals were stibnite(Snt), skinnerite, bournonite,and valentinite. The minerals formed in the order of Py1,Py2–3 + Apy1, Py4–5 + Apy2, Snt, and Py6–7 + Apy3.The δ34S values of the arsenopyrites and pyrites ranged from-5 to 5‰, while those of stibnite were mostly less than-5‰ in the later mineralization stages. Sulfur was provided by deep magmatic hydrothermal fluids, but sedimentary sulfur was added in the later stages. Moreover,the trace elemental contents fluctuated and eventually became similar to those of the sedimentary strata. By comprehensively considering the ores along with the geological characteristics of the deposit, we determined that deep magma provided the Au during ore formation. Later tectonic changes provided Sb from the sedimentary strata,which precipitated along fault expansion areas and produced Au and Sb paragenesis.

Stability of arsenopyrite and As(III) in low-temperature acidic solutions

Arsenopyrite is one of the most important primary arsenic mineral. It is easily oxi-dized under hypergene conditions to release Fe, As, S and other elements. Of the released elements, dissolved arsenic is an extremely toxic element. It is of particular importance to study arsenopyrite and the conversion of As species for environmental protection. This paper deals with the stability of arsenopyrite and As(III) in acidic Fe2(SO4)3 and FeCl3 solutions with the concentrations within the range of 10-2—10-5 mol·kg-1. Experimental researches revealed the following points: (1) under the conditions of the experiment arsenopyrite is unstable and its oxi-dation extent tends to increase with increasing Fe3+ concentration and reaction temperature and decreasing pH; (2) arsenic released during the oxidation of arsenopyrite is dominated by hydrous oxides of As(III); (3) in the FeCl3 solution the oxidation rate of arsenopyrite and As(III) toward As(V) is faster than in the Fe2(SO4)3; and (4) the stability of As(III) tends to increase with de-creasing oxidant concentration and reaction temperature, but to decrease with increasing Cl- concentration and illuminance.

Enhancement of bio-oxidation of refractory arsenopyritic gold ore by adding pyrolusite in bioleaching system

Pyrolusite was added in the bioleaching process to enhance the bio-oxidation process. Bioleaching tests at different dosages of pyrolusite ore, pH and inoculation amounts of Acidithiobacillus ferrooxidans were studied. The results showed that the time of the bio-oxidation process was decreased obviously and the arsenic leaching rate reached 94.4% after the bioleaching. The bio-oxidation of arsenopyrite and the effective extraction of manganese from pyrolusite were achieved by the bioleaching process. After bioleaching, the leaching rate of gold from the reaction residues reached 95.8% by cyanide leaching. In the bio-oxidation process, pyrolusite increased the redox potential of the solution to accelerate the bioleaching rate. The experiment showed that there were two reaction modes in the bioleaching process.

Age and metal source of orogenic gold deposits in Southeast Guizhou Province, China: Constraints from Re-Os and He-Ar isotopic evidence

The orogenic gold deposits in Southeast Guizhou are an important component of the Xuefeng polymetallic ore belt and have significant exploration potential, but geochronology research on these gold deposits is scarce. Therefore, the ore genetic models are poorly constrained and remain unclear. In the present study, two important deposits(Pingqiu and Jinjing) are investigated, including combined Re-Os dating and the He-Ar isotope study of auriferous arsenopyrites. It is found that the arsenopyrites from the Pingqiu gold deposit yielded an isochron age of 400 ± 24 Ma,with an initial ^(187)Os/^(188)Os ratio of 1.24 ± 0.57(MSWD = 0.96). An identical isochron age of 400 ± 11 Ma with an initial ^(187)Os/^(188)Os ratio of 1.55 ± 0.14(MSWD = 0.34) was obtained from the Jinjing deposit. These ages correspond to the regional Caledonian orogeny and are interpreted to represent the age of the main stage ore. Both initial ^(187)Os ratios suggest that the Os was derived from crustal rocks. Combined with previous rare earth element(REE), trace elements, Nd-Sr-S-Pb isotope studies on scheelite, inclusion fluids with other residues of gangue quartz, and sulfides from other gold deposits in the region, it is suggested that the ore metals from Pingqiu and Jinjing were sourced from the Xiajiang Group. The He and Ar isotopes of arsenopyrites are characterized by ~3 He/~4 He ratios ranging from 5.3 × 10^(-4) Ra to 2.5 × 10^(-2) Ra(Ra = 1.4 × 10^(-6), the ~3 He/~4 He ratio of air), 40 Ar=/~4 He ratios from 0.64 × 10^(-2) to 15.39×10^(-2), and ^(40)Ar/^(36)Ar ratios from 633.2 to 6582.0. Those noble gas isotopic compositions of fluid inclusions also support a crustal source origin,evidenced by the Os isotope. Meanwhile, recent noble gas studies suggest that the amount of in situ radiogenic ~4 He generated should not be ignored, even when Th and U are present at levels of only a few ppm in host minerals.

Ore Controls and Metallogenesis of Au-Ag Deposits at Atalla Mine,Central Eastern Desert of Egypt

Gold-silver deposits in the Atalla area occur as hydrothermal quartz veins in NE–SW pre-existing fractures within the Atalla granitic pluton.The orientation of such quartz veins has been attributed to extensional behavior related to the Atalla Shear Zone(ASZ).The Atalla area is covered by a variety of lithologies that are(from oldest to youngest):metasedimentary rocks,metavolcanic rocks,ophiolite assemblage(serpentinites/talc-carbonates),Atalla granite and Dokhan volcanic rocks.Microscopically,Atalla granite ranges in composition from granodiorite to monzogranite.Wholerock geochemistry constrains the calc-alkaine affinity of the Atalla granite that was intruded within an orogenic(syncollision)tectonic regime.The ore minerals are represented by gold/silver(electrum),pyrite(Py1&Py2),arsenopyrite,pyrrhotite,sphalerite,chalcopyrite,galena,covellite and goethite.The temperature of ore formation ranges from 240 to 285℃and the estimated fluid pressure is in the range of 20–100 MPa.Based on the geological setting,ore textures and fluid characteristics;the Atalla Au-Ag deposits are considered to be orogenic in nature,formed from a continental collision(~653-590 Ma),synchronous with the emplacement of calc-alkaline magmatism during the evolutionary history of the Arabian Nubian Shield(ANS).The initial ore-forming fluid was primarily derived from a metamorphic source related to ophiolitic-serpentinite rocks under deep regional conditions of greenschist-amphibolite facies,where the Atalla granitic eruption provided the required temperature conditions for the metamorphic process to take place.Under such conditions,the transportation of ore metals as bisulfide complexes is favoured.The deposition of ore minerals was triggered by fluidwallrock interaction through fracture pathways in conjunction with a temperature-pressure drop that is likely to have been related to uplift into the crustal levels.

Geochemical and geochronological characteristics of the Um Rus granite intrusion and associated gold deposit,Eastern Desert,Egypt

The Um Rus tonalite-granodiorite intrusion(~6 km2)occurs at the eastern end of the Neoproterozoic,ENE-trending Wadi Muba rak shear belt in the Central Eastern Desert of Egypt.Gold-bearing quartz veins hosted by the Um Rus intrusion were mined intermittently,and initially by the ancient Egyptians and until the early 1900 s.The relationship between the gold mineralization,host intrusion,and regional structures has always been unclear.We present new geochemical and geochronological data that help to define the tectonic environment and age of the Um Rus intrusion.In addition,field studies are integrated with EPMA and LA-ICP-MS data for gold-associated sulfides to better understand the formation and distribution of gold mineralization.The bulk-rock geochemical data of fresh host rocks indicate a calc-alkaline,metaluminous to mildly peraluminous,I-type granite signature.Their trace element composition reflects a tectonic setting intermediate between subduction-related and within-plate environments,presumably transitional between syn-and post-collisional stages.The crystallization age of the Um Rus intrusion was determined by in situ SHRIMP 206 Pb/238 U and 207Pb/235U measurements on accessory monazite grains.The resultant monazite U-Pb weighted mean age(643±9 Ma;MSWD 1.8)roughly overlaps existing geochronological data for similar granitic intrusions that are confined to major shear systems and are locally associated with gold mineralization in the Central Eastrn Desert(e.g.,Fawakhir and Hangaliya).This age is also consistent with magmatism recognized as concomitant to transpressional tectonics(D2:~650 Ma)during the evolution of the Wadi Mubark belt.Formation of the gold-bearing quartz veins in NNE-SSW and N-S striking fault segments was likely linked to the change from transpressional to transtensional tectonics and terrane exhumation(D3:620-580 Ma).The development of N-S throughgoing fault arrays and dike swarms(~595 Ma)led to heterogeneous deformation and recrystallization of the mineralized quartz veins.Ore minerals in the auriferous quartz veins include ubiquitous pyrite and arsenopyrite,with less abundant pyrrhotite,chalcopyrite,sphalerite,and galena.Uncommon pentlandite,gersdorffite,and cobaltite inclusions hosted in quartz veins with meladiorite slivers are interpreted as pre-ore sulfide phases.The gold-sulfide paragenesis encompasses an early pyrite-arsenopyrite±loellingite assemblage,a transitional pyrite-arsenopyrite assemblage,and a late pyrrhotite-chalcopyrite-sphalerite±galena assemblage.Free-milling gold/electrum grains(10 sμm-long)are scattered in extensively deformed vein quartz and in and adjacent to sulfide grains.Marcasite,malachite,and nodular goethite are authigenic alteration phases after pyrrhotite,chalcopyrite,and pyrite and arsenopyrite,respectively.A combined ore petrography,EPMA,and LA-ICP-MS study distinguishes morphological and compositional differences in the early and transitional pyrites(PyⅠ,PyⅡ)and arsenopyrite(ApyⅠ,ApyⅡ).Py I forms uncommon small euhedral inclusions in later PyⅡand Apy II.PyⅡforms large subhedral crystals with porous inner zones and massive outer zones,separated by narrow As-rich irregular mantles.The Fe and As contents in PyⅡare variable,and the LA-ICP-MS analysis shows erratic concentrations of Au(<1 to 177 ppm)and other trace elements(e.g.,Ag,Te,and Sb)in the porous inner zones,most likely related to discrete sub-microscopic sulfide inclusions.The outer massive zones have a rather homogenous composition,with consistently lower abundances of base metals and Au(mean 1.28 ppm).The early arsenopyrite(Apy I)forms fine-grained euhedral crystals enriched in Au(mean 17.7 ppm)and many other trace elements(i.e.,Ni,Co,Se,Ag,Sb,Te,Hg,and Bi).On the other hand,ApyⅡoccurs as coarsegrained subhedral crystals with lower and less variable concentrations of Au(mean 4 ppm).Elevated concentrations of Au(max.327 ppm)and other trace elements are measured in fragmented and aggregated pyrite and arsenopyrite grains,whereas the undeformed intact zones of the same grains are poor in all trace elements.The occurrence of gold/electrum as secondary inclusions in deformed pyrite and arsenopyrite crystals indicates that gold introduction was relatively late in the paragenesis.The LAICP-MS results are consistent with gold redistribution by the N-S though-going faults/dikes overprinted the earlier NNW-SSE quartz veins in the southeastern part of the intrusion,where the underground mining is concentrated.Formation of the Um Rus intrusion and gold-bearing quartz veins can be related to the evolution of the Wadi Mubarak shear belt,where the granitic intrusion formed during or just subsequent to D2 and provided dilatation spaces for gold-quartz vein deposition when deformed by D3 structures.

Optimization and mechanism of gold-bearing sulfide flotation

In order to overcome the difficulty of extracting gold from gold-bearing sulfide ore by cyanide process flotation was adopted based on mineralogical analysis Mineralogy shows that gold particles are of superfine structure and mainly enclosed by sulfide ores. Primary gold-bearing sulfide ore is fine-grained pyrite and arsenopyrite. The paper describes the effects of ratios and dosage of activators and collectors on the recovery and grade of gold concentrate. A proper flotation flowsheet was then proposed based on experimental condition and closedcircuit test. The gold concentrate with the gold grade of25.14 g ton-1and the recovery of 86.94 % is obtained after one rougher, three cleaners, and four scavengers from fine grinding flotation process. Furthermore, the mechanisms of combined activators and combined collectors were studied by thermodynamic calculation, and structure-activity relationship of flotation reagent was also explained