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By K. Bunney

A high-pressure laboratory elution rig was commissioned to simulate industrial Zadra and AARL elution conditions for the stripping of gold, silver and mercury from loaded activated carbon. It was found that cyanide was essential for the efficient elution of both mercury and silver, while gold was found to elute most effectively in hot, low-ionic strength solutions. Therefore, the standard AARL-type elution, which implements a cyanide soak and water elution, results in a lower recovery of mercury and silver from the carbon. No single set of conditions was found whereby gold, silver and mercury can all be effectively eluted in a single step. However, sequential elution conditions can efficiently recover all metals and provide a potential approach for separating these metals.

Jan 1, 2010

By J. Choi

For the first time, the influence of stearyl trimethyl ammonium chloride (STAC) as a collector, on the flotation behavior of lepidolite (Uljin, South Korea) was systematically examined in Denver Sub-A cells. Flotation tests were carried out by varying amount of STAC (50?200 g/ton), feed size (-65, -100, -150, and -200 mesh), and solution pH. The impeller speed of 1000 rpm, flotation time of 10 min and AF-65 (a frother) of 250 mL/ton were invariably applied. In order to complement flotation experiments, zeta potential measurements and XRD analysis were conducted. XRD results showed that the ores were mainly composed of lepidolite, muscovite, quartz, calcite and albite. In addition, zeta potential results showed that isoelectric points were about 2.5, 2.3, and 9.7 for quartz, albite, and calcite, respectively, and lepidolite was determined to be less than 2. Overall, the results of 3-stage flotation showed that Li2O grade and recovery tended to increase with increasing STAC dosage and decreasing feed size. In addition, Li2O grade increased with decreasing pH. The results were explained by the extent of the interaction between STAC and each mineral.

Feb 23, 2014

By Boris CARO VARGAS, Bernard Theron

"In early 2014, Nicholson Construction Company was awarded, together with its tunneling sister company Bessac, the Norris Cut Miami Tunnel Project. The 2.5-meters diameter segmental lined tunnel, 1600-meters long, is aimed to replace the existing 54” force main connecting the Waste Water Treatment Plant (WTP) on Virginia Key to Fisher Island. To overcome project challenges such as the highly permeable limestone of the Fort Thomson Karstic Formation (one of the most permeable formation in the World), the project team has developed State of the Art solutions: The TBM was launched with pipe-jacking technique for the first 70-meters and then converted to segment erection mode. It allows substantial schedule savings and drastically reduces the size of the circular launching shaft. The TBM, jointly designed and manufactured by Bessac and Herrenknecht, can convert from slurry to EPB mode within a few minutes. The cutters can be replaced by wet divers thanks to an innovative application in the TBM industry. PRESENTATION OF THE PROJECT The aim of this project is to replace the existing 54-inch force main pipeline which transmitted all sewage collected from Miami Beach, Surfside, Bal Harbour, Bay Harbor, North Bay Village and Fisher Island to the Central District Wastewater Treatment Plant (CDWWTP) to Fisher Island. The existing pipeline consisted of pre-stressed concrete cylinder pipe which is in poor condition in a number of locations and could be subject to sudden failure. An adjacent portion of this existing force main under the Government Cut (North Fisher Island) has already been replaced as part of a previous design-build contract and involved the installation of a 60-inch diameter fiberglass-reinforced mortar pipe installed inside a micro-tunneled casing."

Jan 1, 2016

By Germán Toledo

The closure of TSF represents a critical milestone in the life cycle of mining operations, requiring the integration of technical, environmental, and social dimensions to ensure long-term safety and sustainability. The GISTM introduces the concept of “safe closure” as a demonstrable technical condition in which there are no ongoing material risks to people or the environment. This status must be validated by an independent technical reviewer and formally approved by the Accountable Executive. This article presents a risk-based methodology to support the achievement of safe closure, aligned with the principles and requirements of the GISTM. The proposed approach emphasizes the need to identify, assess, and manage closure and post-closure risks progressively throughout all phases of the TSF life cycle: from site selection and design, through construction and operation, to closure implementation and long-term monitoring. The methodology integrates key elements of effective risk management, including comprehensive knowledge bases, consideration of climate change, credible failure modes, continuous monitoring, stakeholder engagement, and governance. The ALARP principle is applied to demonstrate that residual risks have been reduced to tolerable levels. By incorporating closure planning from the earliest stages and adopting a risk-based view throughout the entire life cycle, this methodology aims to support mining organizations in achieving a verifiable and responsible closure of tailings facilities, in line with international best practices such as those of ANCOLD and ICOLD. The proposed framework offers a practical contribution to strengthening the credibility, effectiveness, and sustainability of tailings closure processes.

Feb 22, 2026

By R. L. Grayson

Compliance standards for respirable dust which are reduced because of high quartz concentrations have become an industry-wide problem. Research on the physical and chemical character of quartz-classified particles in respirable coal mine dusts indicates that they may exist in intermixed layers or may be coated by clay or coal material. The relative amount of intermixing varies with the coal seam being mined. If most of the quartz particles of a mine dust are "pure," then the dust may have a high fibrogenic risk potential because of truly free silica and the compliance standard should be lowered. If, however, the quartz is locked inside another material matrix, or coated, a reduced compliance standard may not be appropriate.

Jan 1, 1990

By Robert J. Ramsey, N. Finkelstein, Robert D. Jeppson

Introduction The Utah Copper Division of Kennecott Copper Corporation will present its contribution to the A. M. Gaudin Flotation Symposium in four parts. The first two segments will discuss briefly the historical development of the Utah Copper Division and describe the ore body. The third segment will review the facilities and operating procedures for the Utah Copper Division's newest plant, the Bonneville Concentrator. The fourth segment describes flotation process circuitry, including molybdenite recovery procedures, at the Arthur and Magna concentrators. (The Bonneville concentrator is a crushing and grinding unit and does not have its own flotation plant). 1. Historical Development Progress through change has been the key to the successful operation of the Utah Copper Division for more than 70 years. As the original low-grade copper operation, the pressures to remain competitive and profitable have dictated the timing and extent of each change. Much of the change has occurred through technological and economic advancements in the area of ore concentration. The Utah Copper Division of Kennecott Copper Corporation had its origin June 4, 1903, when the Utah Copper Company was organized. The initial mill of 300 tpd (tons per day) capacity was built at Copperton a few miles below the present Bingham Canyon mine site. From 1904 to 1910, the Copperton mill was expanded to a capacity of 1,000 tpd, and all of the known apparatus for gravity concentration were evaluated.

Jan 1, 1976

By Libby R. Ricafort, Nonato S. Retardo, Jose B. Anievas

This paper shows the metallurgical test results that led to the design of the heap leach facilities of Philex Mining Corporation. The design incorporates a water management model as process solution circulation is excessive with high rainfall intensity in the area. This poses problems in the operations requiring stringent controls than would be necessary in a less severe environment. The corporate perspective embraces on environmentally-sound mineral development. A budget is always provided to environmental management making certain that no industrial development is moved forward at the expense of the environment.

Jan 1, 1996

By Y. F. Vasyuchkov

In general a term "unconventional mining or "non-traditional mining technology" getting more and more familiar to the mining engineering media. There are several alternating terminological combinations such as "in situ mining", "borehole mining", "shaftless mining", "mineless mining", "geotechnology" etc.; specific terms denote particular method of unconventional mining technology: "underground coal gasification in situ", "underground coal combustion in situ", "borehole hydraulic coal mining" and others. Principal scheme of unconventional coal mining technology is shown in Figure I:

Jan 1, 1997

By C. G. Anderson

The treatment of concentrates for the recovery of the precious metals imposes many processing and environmental challenges. Hydrometallurgical technology for recovery of values from refractory precious metal materials has been developed at Sunshine Mining and Refining Company. Historically, conventional pyrometallurgical methods have been used for to recover values from refractory precious metal materials. However, enhanced environmental awareness has worked to constrain typical refractory material processing methods. This hinders and limits the ability of established smelting or roasting technologies to fill the needs of new sources of refractory materials. An alternative is to treat refractory precious metal bearing materials by hydro metallurgical techniques. These methods are considered more environmentally appropriate since they do not produce gaseous pollutants like sulfur dioxide. Industrially, Sunshine Mining and Refining Company employs hydrometallurgical technology to process refractory precious metal materials. The Sunshine antimony leach uses a mixture of sulfur and caustic under ambient pressure and boiling conditions. The Sunshine oxidation leach uses a mixture of sulfuric acid and a minimal amount of sodium nitrite under relatively mild oxygen pressure and temperature conditions. These conditions result in a nitrogen species catalyzed sulfuric acid pressure leach. Since hydrometallurgical technologies provide industrially proven processing options for many types of refractory precious metal containing materials, their usage should be considered. Ample work has been conducted to prove the effectiveness of Sunshine refractory processing technologies on various materials. This has included platinum group metal materials, refractory gold concentrates, silver materials and indium materials. In some cases, complete process flowsheets have been designed to recover both base and precious metals from these materials and to treat the generated waste streams in environmentally sound manners.

Jan 1, 1996

By M. Stephen Enders

The Little Rocky Mountains host epithermal gold-silver bearing vein and stockwork deposits in a syenite intrusive complex. Pegasus Gold Ltd. is currently mining the oxidized deposits by open-pit methods and recovering gold and silver by heap-leach processes. A geologic program has been designed to effectively determine the basic ore characteristics; 1)mineralization; 2)oxidation; 3)structural setting; 4)lithology; 5)alteration; and ultimately, 6)the leachability of the ore. Geologic mapping, sampling, drilling, assaying, and testing are routinely used in exploration, development, production control, mine planning, and ore reserve estimations. Timely and accurate assay results are essential for the program's success.

Jan 1, 1983

By G. Schriever, H. Thiel, E. J. Foell

A long-term, large-scale, disturbance-recolonization experiment with relevance to the environmental effects of deep seabed mining is described. The study is funded by the German government and was launched in the abyssal eastern tropical South Pacific Ocean in February-March, 1989. After obtaining pre-impact baseline environmental data, a 10.8 km2 (4.2 sq miles) circular area of seafloor was disturbed using a specially designed "plow-harrow" device. An initial post-impact sampling series was carried out immediately after disturbance followed by a second post-impact sampling series six months after the disturbance. Plans call for repeated visits to the site at two year intervals to monitor the anticipated slow recolonization process until the area is inhabited by a new, stabilized community.

Jan 1, 1993

By Solomon J. Salat

During the major expansion of the Inspiration smelter, which took place in 1973, the bulk material handling system underwent a matching expansion in order to move the required materials. Inspiration is the first smelter worldwide to employ electric smelting in conjunction with the use of Hoboken converters (1), (2). The installation includes a 51 -MVA electric furnace, five 4.25m (14-foot) diameter Hoboken converters, rotary dryer, bedding plant, acid plant, heat recovery steam plant, and gas and dust handling system. See Figure 1, Plot Plan. As of today, the 51-MVA electric furnace is the world's largest in the smelting of copper. Engineering design for the installation was per- formed by Treadwell Corporation of New York. The task of designing the conveyor system was complex because the system had to be installed while the smelter was operating and with minimum plant shutdowns, and it had to serve both the existing and the new smelter. Existing conveyors were redesigned where necessary and incorporated into the new conveyor system. See Figure 2, Flow Sheet. The system encompasses the handling of such diverse materials as wet and dry copper concentrates, cement copper, silica flux, cold dope, and concentrate and flue dust.

Jan 1, 1979

By Guy Bridges, Elton Ko, Cheng Ting Ning, Owen Ng, Giovanni Chang, Robert Anderson

"PROJECT OVERVIEWThe Liantang/Heung Yuen Wai Boundary Control Point (BCP) and Associated Works will be the seventhland crossing between Shenzhen and the Hong Kong Special Administrative Region (HKSAR) of China.The project includes site formation of about 23 hectares of land for the development of the BCP and anapproximately 11-kilometre (km) long dual two-lane trunk road (the “Connecting Road”), connecting theBCP with the existing Fanling Highway. The route alignment is within a relatively rural area of HongKong, with very limited similar infrastructure works carried out nearby. It passes beneath bothmountainous terrain, and alluvial plains, and falls within an area of several major regional faults andassociated metamorphism, resulting in a complex variety of ground conditions.ALIGNMENTThe Civil Engineering and Development Department of the Government of the Hong Kong SpecialAdministrative Region carried out extensive public engagement in selecting the alignment of theConnecting Road. Over 70 consultation forums with public bodies, including the District Councils, RuralCommittees, local representatives, etc. were held during the alignment design process. In order toalleviate the concerns of various nearby villages, and to minimize land clearance and environmentalproblems, the original alignment of 10 km long (3.5 km of tunnels and 6.5 km of viaducts) was revised toits final alignment of 11 km long which comprises 5.7 km of tunnels, 4.3 km of viaducts and 1.0 km of atgrade roads.The finally adopted alignment commences at the southern end with an interchange with the existingFanling Highway, part of Route 9, which is a dual three lane expressway currently being widened to dual4 lane. Alongside the expressway is the main rail connection to the mainland of China, and theinterchange viaducts connecting to the southern portal of the Lung Shan tunnel must cross over thisrailway. The southern portal is located in the foothills of Lung Shan, and the 4.8km long tunnel is alignedin a north-northeasterly direction. The southern half passes under mountainous terrain of Lung Shan,and then crosses a valley containing the Kwan Tei river. The northern section comprises low hillsseparated by an alluvial plain and Tan Chuk Hang village area. At the northern end, the tunnel turns tothe north-west to connect with Sha Tau Kok road, an existing single carriageway road, with a newroundabout interchange. Mid-way along this tunnel there will be a ventilation building, connected to the main tunnel by a 330m long ventilation adit. To the north-western side of this interchange is the900m long Cheung Shan tunnel, and after this the remaining 4.3km of the highway connecting with theBoundary Control Point is to be constructed as an elevated viaduct. The alignment is shown in Figure 1."

Jan 1, 2016

By Yves Picot

Construction of new installations was recently completed in the Port of Tubarao, Brazil, With this expansion the port, operated by Companhia Vale do Rio Doce (CVRD), has become the largest iron ore port in the world, with an annual throughput capacity of 60 million long tons. GROWTH OR IRON ORE EXPORTS Since its formation CVRD has steadily increased the shipment of iron ore to overseas markets. Starting with less than 100,000 tons in 1942, the yearly export volume grew to 1,500,000 tons in 1951, 5,000,000 tons in 1961 and 25,000,000 tons in 1971. The number of different grades of ore also increased during this period. Production of high grade pellets, starting in 1970, further increased the number of ore products to be shipped. In the same period the size of ore carriers increased twenty-fold to over 250,000 DWT.

Jan 1, 1974

By M. Shriwas, F. Calizaya

"Recirculation is prohibited in many coal mining countries because of the fear that the re-use of return air would allow the build-up of air contaminants at the workings. The incorrect design and location of a booster fan in any ventilation network can create unsafe condition due to recirculation. The current approach to investigating recirculation using simulation software requires manual effort which becomes tedious in a complex and a large network. An algorithm-based C++ program was designed to detect the recirculation in a booster fan ventilation networks. This program needed an input file prepared from output file generated by any ventilation simulator. This program created an output file for recirculation. This program demonstrated the strong capability to detect the recirculation in a sample network and a coal mine ventilation network. The outcomes of this program were documented in this paper. INTRODUCTION The proper design and location of booster fans eliminate the safety hazards associated with high main fan pressure. Conversely, the incorrect design of booster fans in any ventilation network can create unsafe conditions due to uncontrolled recirculation. The proper utilization of a booster fan derives benefits to reduce the main fan pressure, leakage, and consequently ventilation cost especially with high resistance network due to deep and extensive working area in a mine. However installation of booster fan may create uncontrolled recirculation, if it is not sized and located properly with respect to main fan. Recirculation is prohibited in many coal mining countries because of the fear that the reuse of return air would allow the build-up of air contaminants at the workings. Therefore, it is imperative to check the recirculation while designing and operating booster fan for a ventilation network. This paper deals with an algorithm based C++ program to detect the recirculation in a booster fan ventilation networks. This program was implemented to detect the recirculation in a sample network and a coal mine network. STATEMENT OF PROBLEM The currently available ventilation simulation programs do not give much information about recirculation for the generated solution (fan pressures). The current approach to investigating recirculation using simulation software requires manual effort, i.e., traversing from node to node in the output network by the simulator while keeping tracks of all the nodes that form recirculation paths. This is an easy task in a simple ventilation network, but it becomes tedious and sometimes very confusing in a complex and large network. Moreover, the presence of multiple recirculation paths makes the manual effort more complex and difficult, especially in separating multiple loops that are connected together. Thus, there is a need for a more efficient program that will detect and quantify the recirculation efficiently, for the generated fan pressures. A program is developed to detect the recirculation(s) in a network."

Jan 1, 2015

By R. Bhaskar

The control of quartz levels in the respirable dust requires an approach different from that used to control respirable coal dust. The unique physical properties of quartz have to be utilized when developing quartz dust control systems. Also, techniques that modify the surface properties of quartz dust so that conventional dust control measures are effective should be explored. For instance, the wetting characteristics of quartz can be modified so that the capture efficiency of the quartz dust can be improved. Foam sprays assist in modifying surface wetting characteristics. This paper summarizes the results of a study that was conducted in an operating mine to evaluate the effectiveness of a compressed air foam spray system installed under the boom of a continuous miner and directed so as to cover the pan and the gathering arm. The objectives of the study were to evaluate the effect of the foam underboom sprays on (1) the respirable dust concentration in the ambient air, (2) the quartz concentration in the respirable dust. The engineering design of the foam generation and delivery system is described in the paper, followed by a description of the mine and the dust sampling strategy. The data were analyzed to study the effect of foam on respirable dust and quartz concentrations at the miner cab, face return and the intake. The results of the data analyses and costs are presented in the paper.

Jan 1, 1991

Refractory gold concentrates often contain sub-microscopic gold that is encapsulated within the crystal matrix of iron sulphide minerals such as pyrite, pyrrhotite and arsenopyrite. To recover the gold, the host mineral must generally be broken down chemically, by oxidative processes such as roasting, pressure oxidation or bacterial leaching, which expose the gold for subsequent recovery by leaching in cyanide solution. The focus of attention in these pre-treatment processes is usually the oxidation of the sulphides to elemental sulphur, sulphur dioxide gas or sulphate ions. Less attention is paid to the deportment of iron and the changes in its oxidation state, although this can have a profound effect on gold and silver liberation, as well as down stream operating costs. Iron sulphide minerals break down completely during pressure oxidation, and dissolve in the sulphuric acid solution that is generated from oxidation of the sulphides. This liberates the tiny gold particles that were originally trapped in the sulphide crystals, and gold recovery during subsequent cyanidation is usually very high (>95%). Iron goes into solution in the oxidation process, initially as ferrous sulphate, but this is rapidly oxidized to ferric sulphate, which then hydrolyzes and re-precipitates. The form of the precipitate varies depending on the operating conditions in the autoclave and the presence of certain metal cations. When the acidity in the autoclave is quite low (<20 g/L H2SO4) and the temperature is high (>200OC) the formation of hematite is favoured. When the acidity is high (>20 g/L H2SO4) and the temperature is relatively low (160 to 200OC), the formation of basic iron sulphate is favoured. If the ore or the leach solution contain significant levels of certain cations (such as Na+, K+, NH4+, Ag+ or Pb2+) and the acidity is high (>20 g/L H2SO4), jarosite compounds are favoured. Hematite is the desired iron product in the autoclave discharge, for both metallurgical and environmental reasons, but it is difficult to operate an autoclave under the conditions required for effective liberation of gold without converting some of the iron to basic iron sulphate and/or jarosite. These compounds fall into a category of iron compounds known generically as iron hydroxy sulphates, all of which can cause significant processing and environmental problems in the downstream gold process. This paper deals specifically with basic iron sulphate; the conditions under which it is formed in an autoclave, the problems that are caused by its presence in the feed to a cyanidation plant, and possible remedial strategies that can be adopted, both in the autoclave and downstream.

Jan 1, 2010

By Jacob Carr, Bruce Whisner, Adam Smith, Jingcheng Li

Electromagnetic-based proximity detection systems (PDSs) are utilized on mining machinery to protect workers from being pinned or struck. These systems generate magnetic fields covering the space around a machine, and a miner-wearable component (MWC) detects the field. The PDS determines the distance of miners relative to the machine based on the detected magnetic flux density in the magnetic field. This information is used to establish warning and shutdown zones around the machine. Maintaining a stable magnetic field is essential for system accuracy. However, components used to generate magnetic fields can be influenced by temperature changes. Depending on ventilation conditions and seasonal alternation, a PDS can be subject to significant temperature fluctuation. To better understand and quantify this phenomenon, researchers from the National Institute for Occupational Safety and Health (NIOSH) developed an experimental apparatus to study the influence of temperature on magnetic field generator circuits used in PDSs. Results from the study show that the electric current through a generator can be influenced by both ambient and internal temperatures, modifying the magnetic field that is produced. These findings show that temperature can significantly influence the ability of PDSs, used in underground coal mines, to accurately determine a worker’s position in relation to mining machine.

By H. Walqui

The Empire concentrator currently processes magnetite ore from the Empire pit which is approaching the end of its mine life. Over the past two years plant wide tests have been run to access the plant capability of processing ore from the neighboring sister Magnetite pit. The neighboring pit presents challenges to the Empire plant due to its higher feed grade, finer liberation size and higher percent silica which require additional secondary grinding and concentrating capacity to achieve concentrate grade. The following paper summarizes the results from the second full scale test, run during 2009 under a challenging market environment

Jan 1, 2010

By R. M. Hernandez

The Bureau of Land Management (BLM) constructed four passive biochemical reactor systems (BCRs) to treat mining influenced water (MIW) in the Bunker Hill Superfund area near Coeur D?Alene, Idaho between 2002 and 2003. Initially, the BCRs operated very effectively. However, in the past couple of years, the zinc removal effectiveness of the four BLM BCRs has declined [1]. The central objective of this study was to characterize the microbial communities and substrate present within the BLM BCRs and to use these factors to propose strategies to promote sustained sulfate reduction levels. Microbial communities were characterized by quantifying total bacteria and sulfate reducing species. Substrate was characterized by quantifying the percent organic, acid soluble organic, acid insoluble organic, and bioavailable material within the BCR. The results suggest the depletion of bioavailable organic substrates is the primary cause of the decline in zinc removal and not the microbial community structure. The ability to assess the amount of bioavailable organic substrate and microbial community is important to the understanding of the sulfate reducing capacity of the BLM BCRs and developing strategies to facilitate performance enhancement of the current BLM BCRs. The characterization of organic substrate and microbial community structure are also important to improving design of future passive treatment systems for mining influenced waters.

Jan 1, 2010