Sarcheshmeh Porphyry Copper Mine Research Articles

Improving the accuracy of detecting and ranking favorable porphyry copper prospects in the east of Sarcheshmeh copper mine region using a two-step sequential Fuzzy - Fuzzy TOPSIS integration approach

The detection and prioritization of optimal favorable areas for the ground follow-up stage are among the most challenging issues in the early stages of any mineral exploration program. A common approach to identify the favorable mineralized zones is to create and integrate independent evidential predictor layers using knowledge or data driven approaches. The method proposed in current study is not only capable of detecting favorable zones, but also provides reliable ranking of the best favorable areas to focus in the next exploration stage. For this purpose, a two-step sequential Fuzzy-Fuzzy TOPSIS approach, which deploys the merits of both Multi-Criteria Decision Making (MCDM) and Fuzzy logic inference methodologies simultaneously, is proposed. In the first step, the favorable porphyry copper mineralizations in the east of the well-known Sarcheshmeh porphyry copper mine, are detected through combining evidential layers including geological, remote sensing data, geophysical and geochemical data using fuzzy logic integration approach. As a result of the first step, a number of twenty prospects with the highest porphyry copper favorability membership were selected and inputted into the TOPSIS and fuzzy-TOPSIS algorithms. Subsequently, the chosen prospects were prioritized and ranked according to their scores acquired by each technique of the aforementioned approaches separately. The performance of each approach was evaluated thorough comparison with the known ground porphyry copper mineralizations. The results indicated the capability of the proposed approach not only in detecting favorable porphyry copper mineralization prospects consistent with the previously detected porphyry Cu mineralization but also rank them based on their priorities.

Evaluation of the geometallurgical indices for comminution properties at Sarcheshmeh porphyry copper mine, Iran

Geometallurgy has become an important tool to predict the processing behaviour of ores, and to decrease the production risks associated with the variable nature of economic mineral deposits. Understanding the ore variability and subsequently the response of the ore to processing are considered to be the most important functions of an accurate geometallurgical study. In this paper geometallurgical indices for grinding properties of a copper ore are investigated. Geometallurgical index (GI) is described as any geological feature which makes a footprint on the processing performance of the ores. A comprehensive study at Sarcheshmeh porphyry copper mine was undertaken. This included the process responses of the ore such as grade, recovery and plant throughput as possible geometallurgical indices. In this paper the effects of rock breakage variability on the plant throughput and energy consumption are presented. Ninety samples were collected based on geological features including lithology, hydrothermal alteration, and geological structures. The samples were characterized using X-ray diffraction, X-ray fluorescence, electron and optical microscopy. A small scale simulated test method for Bond ball mill work index (BWI) was used to perform the comminution examinations. The results showed that BWI values vary from 5.67 kWh/t to 20.21 kWh/t. Examination of the possible correlations between BWI and the geological features showed that the key geological feature related to comminution variability is lithology. In addition, the hydrothermal alteration would be an effective parameter in the period that the plant is fed with a single lithology.

Development of geometallurgical indexes (GI) for semi-autogenous milling at Sarcheshmeh porphyry copper mine

Geometallurgy tries to predict the instability the behavior of ores caused by variability in the geological settings, and to optimize the mineral value chain. Understanding the ore variability and subsequently the process response are considered to be the most important functions of an accurate geometallurgical study. In this paper, the geometallurgical index is presented as a new tool to optimize the mining activities. Geometallurgical index is described as any geological feature that makes a footprint on the process performance of ores. In a comprehensive research work at the Sarcheshmeh porphyry copper mine, the geological features that affect the main process responses including the product grade and recovery and plant’s throughput are subjected to investigation. In the current report, the rock hardness variability in terms of semi-autogenous grinding power index (SPI) and its effects on the mill throughput and energy consumption are presented. Ninety samples are collected based on the geological features including lithology, hydrothermal alteration, and geological structures. The samples are mineralogically characterized using XRD, XRF, and electron and optical microscopy. The Starkey laboratory mill, commercialized by Minnovex, is used to perform the SPI comminution test. The SPI results show a wide range of hardness, varying from 12 to 473 minutes. The correlation between the SPI results and the geological features show that lithology is a key geological feature that defines the hardness variability. In addition, the hydrothermal alteration would be an effective parameter in the period that the plant is fed with a single lithology.

Geochemical signatures of waste rocks around Sarcheshmeh porphyry copper mine dumps, southeastern Iran: Implications for exploration, economic by-products and the environment

The Sarcheshmeh porphyry copper deposit (1.7 Gt @ 0.65% Cu, 0.02% Mo, 1.22 ppm Ag, 0.06 ppm Au) is one of the giant Miocene continental arc porphyry ore systems in the Tethyan metallogenic copper belt. The supergene sulfide ore zone (6 Mt. @ 2.43% Cu, 0.022% Mo, 1.55 ppm Ag and 0.114 ppm Au) is mainly capped by a hematitic gossan. This hematitic gossan is a possible surficial exploration target for unexposed porphyry copper ores. The total tonnage of waste rocks is about 2.6 G tonnes of gossanized as well as sulfide-bearing waste rocks with an average modal content of 10% pyrite-chalcopyrite. The gossanized waste rocks show boxwork texture and are composed of hematite, goethite, jarosite, malachite, chalcanthite, brochantite and delafossite. In order to assess the exploration, economic and environmental aspects of chalcophile and precious elements in the waste rocks, a total of 86 waste rocks and 10 residual gossan samples were collected by a systematic random sampling method, analysed by XRF and ICP-MS methods for major oxides and 50 minor and trace elements at ALS Minerals Lab, Ireland. The highly anomalous elements in immature residual gossans are Au (0.775 ppm), Ag (13.4 ppm) and Mo (122 ppm). The gossanized waste rocks are also enriched in Au (0.608 ppm), Ag (87 ppm) and Mo (2960 ppm). These geochemical signatures could be used as possible exploration guides for concealed porphyry copper deposits. The enrichment of Au, Ag and Mo is caused by the lower mobility of these elements in the immature gossans and gossanized waste rocks. The elemental enrichment factors normalized to the Sarcheshmeh ore zone are Au (2.50), Pd (1.05), Ag (4.67), Pb (4.6), Zn (17.34), Sn (2.64), W (1.47), Re (22.22), Se (5.38), Te (5.75), Tl (4.1), Bi (3.29), Ga (1.15), In (11.5), La (1.2), Ce (1.2) and Y (4.1), respectively. The mean contents of the most valuable by-product elements in the gossanized waste rocks include Cu (3168.2 ppm), Mo (180.22 ppm), Au (0.085 ppm), Ag (5.7 ppm), W (42.76 ppm), Re (0.01 ppm), Bi (10.87 ppm) and Se (13.45 ppm). The S-NNP diagram highlights that the sulfide-bearing waste rocks have also a negative impact on the environment, are prone to generate acid mine drainage (AMD) and release the potentially harmful metal (loids): Pb (107 ppm), Zn (365.3 ppm), As (83.53 ppm), Sb (10.24 ppm), In (0.44 ppm), and Se (13.45 ppm) into the surrounding area. These elemental values occurred at concentrations about 4–269 times greater than the crustal abundances and natural background of fresh granodiorite. As such, the heavy metal-rich gossans and sulfide-bearing waste rocks around the Sarcheshmeh mining areas may be considered as an exploration guide for valuable by-product elements as well as environmental concern.

Sub-pixel classification of hydrothermal alteration zones using a kernel-based method and hyperspectral data; A case study of Sarcheshmeh Porphyry Copper Mine and surrounding area, Kerman, Iran

Remote sensing image analysis can be carried out at the per-pixel (hard) and sub-pixel (soft) scales. The former refers to the purity of image pixels, while the latter refers to the mixed spectra resulting from all objects composing of the image pixels. The spectral unmixing methods have been developed to decompose mixed spectra. Data-driven unmixing algorithms utilize the reference data called training samples and end-members. The performance of algorithms using training samples can be negatively affected by the curse of dimensionality. This problem is usually observed in the hyperspectral image classification, especially when a low number of training samples, compared to the large number of spectral bands of hyperspectral data, are available. An unmixing method that is not highly impressed by the curse of dimensionality is a promising option. Among all the methods used, Support Vector Machine (SVM) is a more robust algorithm used to overcome this problem. In this work, our aim is to evaluate the capability of a regression mode of SVM, namely Support Vector Regression (SVR), for the sub-pixel classification of alteration zones. As a case study, the Hyperion data for the Sarcheshmeh, Darrehzar, and Sereidun districts is used. The main classification steps rely on 20 field samples taken from the Darrehzar area divided into 12 and 8 samples for training and validation, respectively. The accuracy of the sub-pixel maps obtained demonstrate that SVR can be successfully applied in the curse of dimensional conditions, where the size of the training samples (12) is very low compared to the number of spectral bands (165).

Phytoextraction-based process of metal absorption from soil in mining areas (tailing dams) by Medicago sativa L. (Alfalfa) (Case study: Sarcheshmeh porphyry copper mine, SE of Iran)

The present work was planned to evaluate the phytoextraction of metal mine tailings, Sarcheshmeh copper mine, SE of Iran, by the endemic plant species Medicago sativa L. (Alfalfa). In this pot experiment, we investigated the effects of seven amendments on the growth of alfalfa and uptaking metals from the mine tailings and stream sediment of tailing dam surface. The mean metal concentrations in both the tailing and stream sediment increased in the order of Hg < Te < Ag < Re < Ge < In < Ga

Environmental mineralogy of Cu-porphyry mine tailings, a case study of semi-arid climate conditions, Sarcheshmeh mine, SE Iran

Sarcheshmeh porphyry copper mine is located in semiarid clime conditions, in the Central Iranian Volcano-Plutonic Copper Belt. Hydro-geochemical and climatological conditions produce suites of secondary mineral assemblages in the Sarcheshmeh mine tailings, which are very interesting and important from the environmental point of view. Solid samples were collected from the fresh and weathered tailings and also from the surface evaporative layer formed on top of the old impoundments. Samples were investigated by using X-ray diffraction (XRD), ore microscopy and chemical fractionation methods. The primary mineralogy of fresh tailings, which is controlled by alteration/mineralization in the Sarcheshmeh mine, was mainly composed of quartz, pyrite, muscovite (sericite), albite, orthoclase, ±clinochlore±chalcopyrite and±illite. This mineral assemblage was subjected to the oxidation/weathering reactions in dried impoundments. Acidic conditions of the weathering zone were compatible with the precipitation of jarosite [KFe3+3(SO4)2(OH)6], hydronium jarosite [(H3O)Fe3+3(SO4)2(OH)6], natrojarosite [NaFe3+3(SO4)2(OH)6], alunite [KAl3(SO4)2(OH)6], butlerite [Fe3+(SO4)(OH)2H2O] and gypsum [CaSO4 2H2O]. A great variety of soluble secondary minerals, typical of arid and semiarid environment, were distinguished in the well-developed evaporative layer on top of the old weathered tailings. These minerals, which are formed due to the upward migration of multi-elemental contaminated waters enriched in Al, Ca, Cl, Cu, Fe2+, Fe3+, H, K, Mg, Mn, Na, O, S, and Zn, were mainly from: (1) simple hydrated sulfate salts of the divalent metal cations (gypsum, hexahydrite, kieserite, leonite, poitevinite, and Zinc-melanterite); (2) simple hydrated salts of the trivalent ions (alunogen, kalinite, and tamarugite); (3) mixed divalent–trivalent salts (lishizhenite, römerite, and Zincobotryogen); and (4) chloride containing minerals (eriochalcite, halite, and mitscherlichite). Secondary minerals in the evaporative zone were found in several unique mineral assemblages such as poitevinite–tamarugite–alunogen–hexahydrite. Formation, transformation, and dissolution of evaporative minerals are induced by the wetting/drying cycles. Mineralogical results, which are supported by the hydro-geochemical and sequential extraction data, are useful for the prediction of contamination potential of tailings, the fate of environmental contaminants, and also the possible remediation strategies.

Study of acid mine drainage production potential in flotation tailings of Sarcheshmeh porphyry copper mine

Acid mine drainage (AMD) is one of the most significant environmental challenges facing the mining industry worldwide. Water infiltrating through the metal sulfide minerals, effluents of mineral processing plants, and seepage from tailing dams becomes acidic, and this acidic nature of the solution allows the metals to be transported in their most soluble form. To predict, prevention and treatment of AMD, wastes, and tailing are subjected to series of evaluations that more include the following: mineralogical and textural evaluation studies, static tests that evaluate the balance between acid generation potential and acid neutralizing capacity and kinetic testing that involve site or laboratory tests which describe the weathering, relative potentials for acid production neutralization, sulfide mineral oxidation rates, potential for metal release, and the effectiveness of control techniques. Sarcheshmeh copper mine in Kerman, Iran, has the most important copper concentration plants in Iran. The plant processes more than 40,000 t of copper feeds and rejects about 39,000 t of tailings containing sulfide minerals such as pyrite. AMD is formed by the oxidation of metal sulfides, mainly pyrite and marcasite, which have been exposed to air and water during and following mining operations. With regard to AMD generation possibility, studies related to the AMD problem were carried out. These evaluations were included site geology study, mineralogical studies, paste pH and modified acid-base accounting (ABA) static tests, and modified humidity cell tests. According to the results, it was demonstrated that long dryness cycles in Kerman result to pyrite weathering and production of AMD.

Determination of Elements Leachability from Sarcheshmeh Porphyry Copper Mine Tailings: Application of Toxicity Characteristic Leaching Procedure

The Toxicity Characteristic Leaching Procedure (TCLP) was applied in order to determine the leachability and mobility of different trace metals and metalloids from the Sarcheshemh Cu mine tailings. Twenty one solid samples were collected from weathered and fresh tailings and also from evaporative secondary minerals and efflorescence salts associated with the oxidation zone of dried tailings. According to the TCLP results, the most leachable and mobile trace elements are Ag, Al, Cd, Ni, S, Se, Co, Cr, Cu, Fe, Mn and Zn. These contaminant elements were concentrated in the surface evaporative layer formed on the top of old weathered tailings. Very high concentrations of Al (27,600 mgL−1), Cu (56,900 mgL−1), Mn (13,260 mgL−1), S (151,800 mgL−1), and Zn (3,935 mgL−1) were observed in the TCLP results of the evaporative samples (mean values are presented). The results obtained from evaporative and efflorescence samples were higher than the regulatory levels for Al, Cu, Cd, Ni, Se, and Zn. The maximum leachability was found for Al and Cu, followed by Ni, Cd, Zn, and Se. The results of this study are useful for the prediction of contamination potential of trace elements and environmental management of mine tailings.

Investigating the origin and geochemical behaviour of toxic elements within the waste dumps using statistical analyses: a case study at waste dumps of Sarcheshmeh copper mine, SE of Iran

Knowledge of the possible origin and behaviour of toxic elements in waste dump systems plays a crucial role in evaluating the potential risks for environment in mining sites. Sequential extraction experiments are often used to investigate the origin and behaviour of toxic elements. However, these experiments are not common in waste dumps due to need of the large number of samples for considering the heterogeneity. Therefore, this paper attempts to determine the origin and behaviour of Cd, Cu, Cr, Mo, Pb and Zn in waste dump using statistical analyses. For the aim of this study, sixty samples were collected from two waste dumps at the Sarcheshmeh Copper mine in Kerman province of Iran. The samples were characterised via ICP, XRD, ASTM-D2492 and paste pH experiment. Principle component analysis (PCA), hierarchical cluster analysis (HCA) and correlation analysis (CA) were used to identify the relationship and interdependency amongst the concentrations of toxic elements and the exact mineral contents. For detailed investigation, the samples were classified according to the paste pH value and then correlation analysis (CA) was performed. The results in comparison with previous experimental investigations revealed that pyrite and aluminosilicate minerals were the main sources of contamination. It was also found that hydroxysulphate minerals, manganese and iron oxyhydroxides, muscovite and chlorite were the principal minerals which control the concentrations of toxic elements in the waste dumps of the Sarcheshmeh porphyry copper mine.

Geochemistry of Trace Metals and Rare Earth Elements in Stream Water, Stream Sediments and Acid Mine Drainage from Darrehzar Copper Mine, Kerman, Iran

Darrehzar porphyry copper mine is located 10 km south of the famous Sarcheshmeh porphyry copper mine in Kerman province, Iran. Water and sediment samples in the Darrehzar porphyry copper mine were collected and analyzed in order to characterize the environmental effects of regional geology and mining activity. Stream affected by acid mine drainage (AMD) are \({\hbox {Ca}}{-}{\hbox {SO}}_{4}^{2-}\) in type, while unaffected streams are \({\hbox {Ca}}{-}{\hbox {HCO}}_{3}^{- }\) type. Acid drainage, with pH values as low as 2.5, is quite rich in dissolved copper (mean 306.53 mg/L) \(>\) iron (77.83 mg/L) \(>\) aluminium (48.62 mg/L) \(>\) manganese (6.90 mg/L) \(>\) zinc (2810.42 \(\upmu \)g/L) \(>\) cobalt (831.55 \(\upmu \)g/L) \(>\) nickel (298.47 \(\upmu \)g/L). The high sulfate concentration makes sulfate the major controlling factor of electrical conductivity. The strong correlation among the majority of the elements indicates either similar geochemical behavior or a common origin, (mostly sulfides). Calculation of Acid Mine Drainage Index (AMDI) indicates that Darrehzar mine is classified as dangerous in view of AMD hazards. In Darrehzar porphyry copper mine, total rare earth element content (\(\Sigma \)REE) in AMD (5.54–417.76 \(\upmu \hbox {g L}^{-1})\) is higher than natural water (REE in upstream and downstream water is 0.87–1.40 and 0.83–1.71 \(\upmu \hbox {g L}^{-1}\)respectively). The North American Shale Composite (NASC) normalized REE patterns of AMDs revealed strong enrichment of middle REE (MREE), and heavy REE (HREE) compared with light REE (LREE). Speciation modeling indicates the predominance of aqueous species i.e., \(\hbox {LnSO}_{4}^{+}\), \(\hbox {Ln} (\hbox {SO}_{4})_{2}^{-}, \hbox {Ln}^{3+}, \hbox {LnCO}_{3}^{+}, \hbox {LnHCO}_{3}^{2+}\) and \(\hbox {Ln} (\hbox {CO}_{3})_{2}^{-}\) (Ln refers to any lanthanide element). In upstream, where pH is 7.2 \(\le \) pH, REEs primarily exist as \(\hbox {LnCO}_{3}^{+}\), and HREE bicarbonate complexes (Ln \((\hbox {CO}_{3})_{2}^{-})\) exceed those of LREEs. Based on mean geoaccumulation indices (\(I_\mathrm{{geo}}\)), Darrehzar river sediments at mine site display the following trend: \(\hbox {Cu}>\hbox {Mo}>\hbox {Pb}>\hbox {Sb}>\) Cd. Calculated potential ecological risk index (RI) indicates higher risk at mine site. The mean potential ecological risk factors \((\hbox {E}_{\mathrm{i}})\) for sediment metals display the following trend: \(\hbox {Mo}>\hbox {Cd}>\hbox {Cu}>\) As \(>hbox{Pb}>\hbox {Ni}>\hbox {Cr}> \hbox {Zn}\).

Characterisation of the Sarcheshmeh copper mine tailings, Kerman province, southeast of Iran

Mineral processing operation at the Sarcheshmeh porphyry copper mine has produced huge quantities of tailings materials containing sulphide minerals in particular pyrite. These tailings materials were geochemically and mineralogically characterised to assess pyrite and chalcopyrite oxidation, acid mine drainage generation, and trace element mobility to lead development of a proper remediation plan. Five vertical trenches up to 4.2 m deep were excavated from the tailings surface, and 70 solid samples were taken in 0.3 m intervals. The samples were first mineralogically analysed. Pyrite was the main sulphide mineral found in the tailings. The gangue minerals include quartz ± muscovite–illite ± chlorite ± albite ± orthoclase ± halite. The samples were geochemically analysed for total concentrations of 62 elements, paste pH, SO4 2−, CO3 2−, and HCO3 −. The maximum concentrations of SO4 2− (1,300, 1,170, 1,852, 1,960 and 837 mg/L) were observed at a depth of 0.9 m in profiles A, B, C, D and E, respectively. The tailings have a high acid-producing potential and low acid-neutralising potential (pyrite 4–6 wt %, calcite 1 wt %). Fe2(SO4)3, CuSO4, MgSO4 and MnSO4 were the dominant secondary sulphate minerals in the tailings. The lowest pH values (2.9, 3 and 3) were measured at a depth of 0.3 m in the profiles A, B and C, 3.9 at a depth of 0.6 m in the profile D and 3 at a depth of 0.9 m in the profile E. The upper portions of the profiles C (1.8 m) and D (2.1 m) were moderately oxidised, while oxidation in the profiles A, B and E did not extend more than 1.2, 1.2 and 1.5 m beneath the tailings surface. Zn, Pb, Rb, U, Hf, Nd, Zr and Ga show almost a constant trend with depth. Cd, Sr, Th, La and Ce increased with increasing depth of the tailings materials while, Co, V, Ti, Cr, Cu, As, Mn, Ag, Mo and Ni exhibit initially a decreasing trend from tailings surface to the depths that vary between 0.9 and 1.2. They then remained constant with the depth. The results show pyrite and chalcopyrite oxidation at surface layers of the tailings and subsequent leaching of the oxidation products and trace elements by infiltrated atmospheric precipitation.

Geochemical behavior and speciation modeling of rare earth elements in acid drainages at Sarcheshmeh porphyry copper deposit, Kerman Province, Iran

Acid mine drainage is a major source of water pollution in the Sarcheshmeh porphyry copper mine area. The concentrations of heavy metals and rare earth elements (REEs) in the host rocks, natural waters and acid mine drainage (AMD) associated with mining and tailing impoundments are determined. Contrary to the solid samples, AMDs and impacted stream waters are enriched in middle rare earth elements (MREEs) and heavy rare earth elements (HREEs) relative to light rare earth elements (LREEs). This behavior suggests that REE probably fractionate during sulfide oxidation and acid generation and subsequent transport, so that MREE and HREE are preferentially enriched. Speciation modeling predict that the dominant dissolved REE inorganic species are Ln3+, Ln(SO4)2−, LnSO4+, LnHCO32+, Ln(CO3)2− and LnCO3+. Compared to natural waters, Sarcheshmeh AMD is enriched in REEs and SO42−. High concentrations of SO42− lead to the formation of stable LnSO4+, thereby resulting in higher concentrations of REEs in AMD samples. The model indicates that LnSO4+ is the dissolved form of REE in acid waters, while carbonate and dicarbonate complexes are the most abundant dissolved REE species in alkaline waters. The speciation calculations indicate that other factors besides complexation of the REE's, such as release of MREE from dissolution and/or desorption processes in soluble salts and poorly crystalline iron oxyhydroxy sulfates as well as dissolution of host rock MREE-bearing minerals control the dissolved REE concentrations and, hence, the MREE-enriched patterns of acid mine waters.

Chemical Fractionation and Contamination Intensity of Trace Elements in Stream Sediments at the Sarcheshmeh Porphyry Copper Mine, SE Iran

This paper presents chemical fractionation and contamination intensities of trace elements in stream sediments at the Sarcheshmeh mine, southeastern Iran, which is one of the world’s largest Oligo-Miocene porphyry copper deposits. Evaluation of environmental pollution indices and maximum probable background concentrations revealed that As, Cu, Cd, Mo, Pb, Sb, Se, S, and Zn are highly concentrated in the contaminated sediments, while Cr, Co, Ni, Fe, and Mn show lower enrichment values. Discharges of industrial effluents (especially those contaminated by tailings), reject waste from the semi-autogenous mill, and rock waste drainages are the main anthropogenic contaminant sources. High values of As, Cu, Fe, Mo, Pb, and Zn were associated with the oxidizable, primary sulfide, and residual sediment fractions. Relatively high percentages of Co (>92 %), Cr (>58 %), Cu (>79 %), Fe (>40 %), Mn (>97 %), Ni (>87 %), and Zn (>83 %) in the sediments associated with the rock waste drainages were readily released during the extraction of water-soluble, exchangeable, and carbonate fractions. Sediments that received reject waste drainages were also polluted by As (>351.7 mg kg−1), Cu (>1.58 %), Mo (>91.8 mg kg−1), Pb (>291.8 mg kg−1), and Zn (>762.4 mg kg−1). A large percentage of these contaminants were found to be adsorbed and co-precipitated with amorphous Fe-oxides and carbonate phases. The chemical fractionation pattern of the potentially hazardous trace elements corresponded well with the mineralogical composition of the contaminated sediments.

Application of multivariate statistical methods to indicate the origin and geochemical behavior of potentially hazardous elements in sediment around the Sarcheshmeh copper mine, SE Iran

Multivariate statistical techniques, i.e., correlation coefficient analysis, principal components analysis (PCA), and hierarchical cluster analysis (CA), were applied to the total and water-soluble concentrations of potentially hazardous metals in sediments associated with the Sarcheshmeh mine, one of the largest Oligo-Miocene porphyry copper deposits in the world. The samples were analyzed for hazardous metal concentration levels by inductively coupled plasma mass spectrometry method. Results indicate that the contaminant metals As, Cd, Cu, Mo, S, Sb, Sn, Se, Pb, and Zn were positively correlated with the total concentrations. These hazardous metals also have strong association in the PCA and CA results. Different anthropic versus natural sources of contaminant metals were distinguished by using CA method. Water-soluble fraction of hazardous metals showed that the hydro-geochemical behavior of these metals in sediments is different considerably. Elements such as Cd, Co, Cr, Cu, Fe, Mn, Ni, S, and Zn are readily water soluble from contaminated samples, especially from evaporative mineral phases, while the release of As, Mo, Sb, and Pb into the water is limited by adsorption processes. Results obtained from the application of multivariate techniques on the water-soluble fraction data set show that the hazardous metals are categorized into three groups including (1) Ni, S, Co, Cu, Cr, and Fe; (2) Se, Mn, Cd, and Zn; and (3) Sb, As, Mo, and Sn. This classification describes the hydro-geochemical behavior of hazardous metals in water–sediment environments of the Sarcheshmeh porphyry copper mine and can be used as a basis in remedial and treatment strategies.

Lime Treatment of Mine Drainage at the Sarcheshmeh Porphyry Copper Mine, Iran

Laboratory and field treatment tests were performed to evaluate the effectiveness of lime treatment for mitigation of environmental effects of acid mine drainage (AMD) at the Sarcheshmeh porphyry copper mine. AMD associated with the rock waste dumps is contaminated with Al (>36,215 μg/L), Cd (>105 μg/L), Co (>522 μg/L), Cu (>53,250 μg/L), Mn (>42,365 μg/L), Ni (>629 μg/L), and Zn (>12,470 μg/L). The concentrations of other metals (Fe, Mo, Pb, and Se) are low or below detection limits (As, Cr, and Sb). Due to the very high Al and Mn content and the low concentration of Fe, a two-stage lime treatment method was chosen for the laboratory tests. In the first stage, the AMD was treated at four pH set points: 7.5, 8.9, 9, and 10. In the second stage, after removing the sludge at pH 9, treatment was continued at pH 10 and 11. The results indicated that a two-stage treatment method was not necessary because elements such as Al, Cu, Co, and Zn were easily treated at pH 7.5, while complete removal of Cd, Mn, and Ni only required a pH of 10. Increasing pH during the treatment process only caused a slight increase in Al. Field treatment tests support the laboratory results. Lime treatment of highly contaminated AMD from dump 11, using simple low density sludge pilot scale equipment, show that contaminant metals are treatable using this method. The mean treatment efficiency for contaminant metals was 99.4% for Al, % for Cd, 99.6% for Co, 99.7% for Cu, 98.5% for Mn, 99.7% for Ni, 99% for U, and 99.5% for Zn. The optimum pH for AMD treatment by lime was in the range of 9–10. The produced sludge in the treatment process was highly enriched in the contaminant metals, especially Cu (>7.34%), Al (>4.76%), Mn (>2.94%), and Zn (>1.25%). A correlation coefficient matrix indicates that the distribution pattern of the contaminant metals between soluble and precipitated phases is consistent with the hydrochemical behavior of the metals during the lime treatment process.

Prediction of heavy metals in acid mine drainage using artificial neural network from the Shur River of the Sarcheshmeh porphyry copper mine, Southeast Iran

Water is one of the basic and fundamental requirements for the survival of human beings. Mining of the sulphide mines usually produce a significant amount of acid mine drainage (AMD) contributing to huge amounts of chemical components and heavy metals in the receiving waters. Prediction of the heavy metals in the AMD is important in developing any appropriate remediation strategy. This paper attempts to predict heavy metals (Cu, Fe, Mn, Zn) from the AMD using backpropagation neural network (BPNN), general regression neural network (GRNN) and multiple linear regression (MLR), by taking pH, sulphate (SO4) and magnesium (Mg) concentrations in the AMD into account in Shur River, Sarcheshmeh porphyry copper deposit, southeast Iran. The comparison between the predicted concentrations and the measured data resulted in the correlation coefficients, R, 0.92, 0.22, 0.92 and 0.92 for Cu, Fe, Mn and Zn ions using BPNN method. Moreover, the R values were 0.89, 0.37, 0.9 and 0.91 for Cu, Fe, Mn, and Zn taking the GRNN method into consideration. However, the correlation coefficients were low for the results predicted by MLR method (0.83, 0.14, 0.9 and 0.85 for Cu, Fe, Mn and Zn ions, respectively). The results further indicate that the ANN can be used as a viable method to rapidly and cost-effectively predict heavy metals in the AMD. The results obtained from this paper can be considered as an easy and cost-effective method to monitor groundwater and surface water affected by AMD.

Bio-Remediation of Acid Mine Drainage in the Sarcheshmeh Porphyry Copper Mine by Fungi: Batch and Fixed Bed Process

Acid mine drainage (AMD) containing high concentrations of iron and sulphate, low pH and variable concentrations of heavy metals leads to many environmental problems. The concentrations of Cu and Mn are high in the AMD of the Sarcheshmeh porphyry copper mine, Kerman province, south of Iran. In this study, the bio-remediation of Cu and Mn ions from acid mine drainage was investigated using two native fungi called Aspergillus niger and Phanerochaete chrysosporium which were extracted from the soil and sediment samples of the Shour River at the Sarcheshmeh mine. The live fungi was first harvested and then killed by boiling in 0.5 N NaOH solution. The biomass was finally dried at 60 C  for 24 h and powdered. The optimum biosorption parameters including pH, temperature, the amount of biosorbent and contact time were determined in a batch system. The optimum pH varied between 5 and 6. It was found that the biosorption process increased with an increase in temperature and the amount of biosorbent. Biosorption data were attempted by Langmuir and Freundlich isotherm models and showed a good match. Kinetic studies were also carried out in the present study. The results show that the second-order kinetics model fits well the experimental data. The biosorption experiments were further investigated with a continuous system to compare the biosorption capacities of two systems. The results show that biosorption process using a continuous system increases efficiency up to 99%. A desorption process was eventually performed in order to recover Copper and Manganese ions. This process was successful and fungi could be used again.

Environmental geochemistry of toxic heavy metals in soils around Sarcheshmeh porphyry copper mine smelter plant, Rafsanjan, Kerman, Iran

The Sarcheshmeh copper mine smelter plant is one of the biggest copper producers in Iran. Long-time operation of about 25 years of the smelter plant causes release of potentially toxic heavy metals into the environment. In this paper, geochemical distribution of toxic heavy metals in 28 soil samples was evaluated around the Sarcheshmeh smelter plant. Soils developed over the nonmineralized and uncontaminated areas have an average background concentration of 41.25 mg kg−1 Cu, 26.6 mg kg−1 As, 12.7 mg kg−1 Pb, 0.9 mg kg−1 Sb, 1.9 mg kg−1 Mo, 1.7 mg kg−1 Sn, 0.2 mg kg−1 Cd, 0.15 mg kg−1 Bi, 235 mg kg−1 S and 73.4 mg kg−1 Zn, respectively. As a result of smelting process, the upper soil layers (0–5 cm) were polluted by Cu (>1,397 mg kg−1), Cd (>3.42 mg kg−1), S (>821 mg kg−1), Mo (>10.3 mg kg−1), Sb (>11.7 mg kg−1), As (>120.6 mg kg−1), Pb (>83.8 mg kg−1), Zn (>214.9 mg kg−1), and Sn (>3.7 mg kg−1), respectively. These values are much higher than the normal concentration of the elements in the uncontaminated soil layers. The elemental values decrease with distance travelled away of the smelter plant, especially at minimum wind direction. Furthermore, high contaminated values of Cu (8,430 mg kg−1), As (500 mg kg−1), Pb (331 mg kg−1), Mo (61 mg kg−1), Sb (56.2 mg kg−1), Zn (664 mg kg−1), Cd (17.2 mg kg−1), Bi (13.4 mg kg−1), and S (3,780 mg kg−1) were observed in the upper soil layers close to the smelting waste dumps. Sequential extraction analysis shows that about 270 mg kg−1 Cu, 28 mg kg−1 Pb, 50.33 mg kg−1 Zn, and 47.84 mg kg−1 As were adsorbed by Fe and Mn oxides. The carbonate phases include 151 mg kg−1 Cu, 28 mg kg−1 Pb, 25 mg kg−1 Zn, and 32.99 mg kg−1 As. Organic matter adsorbed 314.6 mg kg−1 Cu and 29.18 mg kg−1 Zn.

Mine drainage water from the Sar Cheshmeh porphyry copper mine, Kerman, IR Iran

This paper presents the results of a study on stream and mine waters in the area of one of the world largest porphyry copper deposit located in the southeastern Iran, the Sar Cheshmeh porphyry copper mine. Trace metals are present as adsorption on Fe and Mn oxide and hydroxide particles, as sulfate, simple metal ions, and scarcely as adsorption on clay particles and hydrous aluminium oxides. Mean pH decreases and the mean concentration of trace elements, EC and SO4(2-) increases from the maximum discharge period (MXDP) during snow melt run off (May), through the moderate discharge period (MDDP; March and July) to the minimum discharge period (MNDP; September). Water samples have sulfatic character essentially, however, from the MNDP through the MDDP towards the MXDP they show a bicarbonate tendency. This study indicates that the surface waters draining the Sar Cheshmeh open pit have a higher pH and lower concentration of trace metals compared with some other porphyry copper deposits.