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By R. D. Williams

Several hydrometallurgical leach processes have been recently proposed for the recovery of copper from copper concentrates. These include the Cymet Process of Cypress Metallurgical Processes Corporation, the Arbiter Process of the Anaconda Company, and the Treadwell Process of Treadwell Engineering company(1). These processes and similar processes for recovery of other minerals, have several phenomenological similarities which make their quantitative description difficult at best. These include (a) the presence of more than one phase, (b) non-uniform mineralization of the feed concentrate, (c) surface and diffusional effects, and (d) a particle size distribution which varies with time. Semi-theoretical, rather than purely empirical, treatment of such processes in their developmental stages will result in a better understanding of the physico-chemical mechanisms in effect. This, in turn, will allow reliable process designs to be made on reasonable time scales for reasonable development costs. Once a production unit is built, such an approach will provide straightforward methods for process control and optimization. A research and development effort to determine criteria and procedures for semi- theoretically characterizing such mineral leach recovery processes has been initiated in a joint venture by the Arizona Bureau of Mines and the College of Mines at the University of Arizona. This group has as its task the mathematical characterization of hydrometallurgical leach recovery processes using semi- theoretical mechanisms for the underlying phenomena. The resulting models are experimentally verified and parameterized on the laboratory scale in such a way that they can be utilized with similarity criteria to provide reliable scaleup to production designs. This discussion will be centered around the elements of such an approach and how they fit together.

Jan 1, 1975

By Earl M. Woodward

INTRODUCTION Kerckhoff-2 is a 140 MW underground hydro-electric project designed and owned by Pacific Gas and Electric Company and constructed between May, 1980 and May, 1983 by Auburn Constructors. The project is located in the western foothills of the Central Sierra Nevada Mountains, about 30 miles northeast of Fresno, California, and develops the power potential of the lower San Joaquin River and its tributaries between the existing Kerckhoff and Millerton Lakes. The Kerckhoff-2 Project consists of project roads, adits, and access tunnels, service tunnels, power tunnels, powerhouse, tailrace tunnel surge shaft, buss shaft, intake structure, discharge structure, and switchyard. In the 1920s, the Kerckhoff 1 project, consisting of a dam, reservior, tunnel, and 34 MW powerhouse, was built in the same general area as Kerckhoff-2. The tunnel was constructed by conventional methods, and was left unlined. In time, other projects were built upstream, allowing the flow of the San Joaquin River to be regulated. The Kerckhoff 2 project is designed to harness that regulated flow, providing an additional 140,000 ON of power. Kerckhoff 2 will be the primary power plant; Kerckhoff I will produce power whenever the flow rate exceeds 4,800 cubic feet. The new power tunnel is built along the east side of the San Joaquin River between Kerckhoff and Millerton Lakes, parallel to the existing tunnel but extending approximately one mile further downstream.

Jan 1, 1983

By A. Iordanidis

Ieropigi Fe-Ni deposit is located in northern Greece, in Kastoria?s prefecture near Albania?s borders. A laterite profile exposed by opencast mining and placed near the basement of the mine was chosen for sampling. Ten samples, representing ?pure? Fe-Ni ore, ophiolite-bedrock, ?red? ophiolite and ?enriched? ophiolite were collected, based on macroscopic observation. The samples were analysed by X-Ray powder Diffraction (XRD) for the determination of the mineral phases. Iron and Nickel concentrations of the same samples were also determined by X-Ray Fluorescence (XRF) methodology. The Fe-Ni ore samples consists predomi-nantly of hematite, goethite, chrysotile (serpentine), saponite and quartz. ?Red? ophiolite samples consists mainly of chrysotile, hematite, quartz, calcite and small amounts of paragonite and goethite. Bedrock and ?enriched ophiolite samples are comprised of chrysotile, hematite, calcite, quartz, nontronite, paragonite and sepiolite. The Fe content ranges between 13% and 49% in Fe-Ni ore samples and between 7% and 10% in ophiolite samples. The Ni content ranges between 1% and 3% in Fe-Ni ore samples and between 0.3% and 4.5% in ophiolite samples (the higher content is observed in the so-called ?enriched? ophiolite). A correlation between Fe-Ni concentrations and mineral assemblages is being attempted in order to evaluate the nickel-rich mineral phases. It is shown that the nickeliferous minerals are serpentine, hematite, goethite and saponite.

Jan 1, 2006

By P. T. Luckie

The selectivity curve -- a continuous function which predicts the expected proportion of feed material of a particular size that will appear as coarse material -- is the preferred model for describing classification. In a previous paper (I), the authors presented a technique for determining the selectivity curve of a classifier from experimental data. The separation process is defined by a binomial distribution of the form [ ] where s(x), the probability of particles of size x reporting to the coarse stream, is obviously the selectivity value for material of size x.

Jan 1, 1975

By L. B. Phelps

Many coal mining companies have potential surface mine reserves which either are known or suspected to have had prior drift mining activity on them. In many cases, there is no documentation on these mines or at best, very fragmented records. These undocumented abandoned underground mines are creating engineering, financial, and environmental difficulties and concerns for both surface coal mine operators and regulatory personnel. This paper examines the use of resistivity techniques in detecting entries of abandoned drift coal mines. The detection of such a drift mine entry would confirm the presence and orientation of an abandoned underground coal mine.

Jan 1, 1985

By Roussos Dimitrakopoulos, Liam Findlay

Semimobile in-pit crushing and conveying (IPCC) systems can help reduce truck haulage in openpit mines by bringing the crusher closer to the excavation areas. Optimizing a production schedule with semimobile IPCC requires integrating extraction sequence, destination policy, crusher relocation, conveyor layout and truck fleet investment decisions. A mining complex with multiple mines and IPCC systems should be optimized simultaneously to find an optimal schedule for the entire value chain. An integrated stochastic optimization framework is proposed to produce long-term production schedules for mining complexes using multiple semimobile IPCC systems. The optimization model has flexibility to select the crusher locations and conveyor routes from anywhere inside the pits. The framework uses simulated orebody realizations to consider multielement grade uncertainty and manage associated risk. A hybrid metaheuristic solution approach based on simulated annealing and evolutionary algorithms is implemented. The method is demonstrated using an iron ore mining complex

Nov 1, 2024

By Mark E. Gershon

A mixed-integer formulation of the mine scheduling problem is discussed and applied for the purpose of optimizing both the mine production sequencing and the mill blending and processing problems simultaneously. Previous attempts at solving these problems separately, although successful, fail to take into account the interrelationships between these problems. Project structure serves as the outline of this paper, which is directed towards a mining engineering audience. Generalized in its organization, this concept is useful for long, intermediate and short range scheduling. Actual applications are mentioned which show that the concept is also applicable to mining a variety of ores.

Jan 1, 1982

By William D. Leech, Peter S. Buskirk

Virginia Electric and Power Company commencing in early 1985 will begin operating the Bath County Pumped Storage hydroelectric facility, presently the largest capacity installation of its kind. Six concrete lined vertical shafts, 3 ea x 44.0 ft (13.4m) diam x 330 ft (100m) and 3 ea x 28.5 ft (8.7m) diam x 740 ft (226m), comprise a portion of the three underground power conduits. The project team decided to employ the slipform over the conventional jump form method. This selection was based on the engineer's hydraulic design and the contractor's performance requirements. This paper presents the key elements of the shafts' successful slipform operations. The contractor achieved slip rates as high as 60 ft (18m) per day; and the owner received competent permanent linings as specified by the engineer. The authors describe the team's effort to progressively improve both concrete quality and placement rate.

Jan 1, 1985

By C. Jardine

The concept of the system is to minimize costly unscheduled breakdowns of equipment by replacing components earlier than their "life" expectancy. Periodic unit services are scheduled according to pre-set constraints. Service sheets are generated by matching a job and component master listing based on assigned cyclic component lives. The system can provide accountability of all man-hours reported and history information can be selectively retrieved. By reducing unscheduled equipment shutdowns, this system allows for better utilization of manpower and an overall improvement in equipment reliability and availability.

Jan 1, 1979

By L. J. Habegger

This paper considers the potential water quality impacts of future energy scenarios which project an approximate doubling of coal utilization from 1975 to 1985. The major impacts estimated for coal extraction are related to effluents from unregulated activities (reclaimed areas prior to stable vegetation) and pollutants (e.g., metals and ammonia). Where applicable, the EPA effluent guidelines to be in effect by 1983 reduce the impact of individual sources to low levels. For example, total suspended solids and acidic discharges are to be regulated to levels generally below recommended water quality standards for receiving streams. However, implementation of these guidelines, particularly for coal extraction, has not been demonstrated on a wide scale. Water quality is not expected to be a major constraining factor for increasing capacity of coal fired utility and industrial boilers. Water quality control has not been demonstrated on a commercial scale for coal conversion to synfuels, but adequate control technologies appear to be feasible.

Jan 1, 1978

By T. Harrison

Surface coal mines in West Virginia are receiving stringent NPDES discharge limits for total recoverable selenium. With limits in the low parts-per-billion range, selection and implementation of proper sample collection and analytical methods are imperative for quality assurance and control and for consistency in results. Given the typical oxidized form of selenium in the water, the low limits and the large and variable flow rates from the watersheds, end-of-pipe treatment is difficult and cost-prohibitive to implement. Discharge locations in the remote and steep terrain exacerbate the problem. To evaluate options for end-of-pipe treatment at a Patriot Coal Corporation surface mining operation in West Virginia, CH2M HILL performed wastewater characterization for a range of key constituents and selenium species at three outfalls for selection and preliminary sizing of appropriate treatment processes. A preliminary evaluation of base and wet-weather flows was done to understand flow variability considerations for discharges. A conceptual evaluation of technologies to treat selenium to permitted levels was conducted in con-junction with order-of-magnitude life-cycle cost estimates.

Jan 1, 2010

By Jack S. Watson, Rasika Nimkar, Robert M. Counce, Matthew Gordy, Patrick Zhang

Waste phosphatic clay presents a difficult disposal problem and a significant loss of P2O5. Recent developments make this study on the use of phosphatic clay as a feed material for H3PO4 production worthwhile. (a) New data from Florida Industrial and Phosphate Research Institute (FIPR) suggest that the Bclay^ waste can be effectively treated by improved solid separation coupled with flotation to produce feed material for recovering additional phosphate. (b) The use of BOLI Flowsheet^ provides capability to predict performance of aqueous-based processes for a range of possible operating conditions. Using the new FIPR data and BOLI Flowsheet^ enabled the design of a new process that can potentially extend the usefulness of current P2O5 ore deposits. Predictions using OLI Flowsheet were able to identify process conditions that effectively overcome the difficulty of high Mg content of phosphatic clay. Estimated manufacturing cost in the current study lead to valuation of the P2O5 content of the phosphatic clay recovered/utilized at 60 to 70% of that of the phosphate rock feed material currently used. Phosphatic clay should be considered as a valuable material that is currently given zero value. The new FIPR data and BOLI Flowsheet^ enables the design of a new process that can potentially extend the usefulness of current phosphate ore deposits by extending the fraction P2O5 of recovered

By Gregory M. Rumbaugh, Todd R. Kostecki, Christopher Mark

From 2015 to 2021, five massive pillar collapses occurred at four underground stone mines in the eastern USA. These events resulted in powerful airblasts that damaged mine infrastructure and mobile equipment, seriously injured miners, and disrupted underground travelways. Each of these pillar collapses propagated through the overlying strata, causing a subsidence sinkhole on the surface. Pillar collapses are particularly hazardous for miners because they can occur with little warning and can affect miners that are far from the pillar collapse area. The following case studies show that certain factors may increase the likelihood of a pillar collapse. For instance, each of the 5 events involved at least 12 benched pillars with width-to-height ratios (w/h) of 0.8 or less. This study elaborates on these factors and proposes a framework to assist mine operators where they identify similar hazards.

Jul 24, 2023

By Yuting Xue, Khaled Mohamed

Rib control is a critical component of underground coal mining operations, and comprehensive rib support design is essential for ensuring the safety of miners. However, there is currently no standardized approach for rib support design in the United States. To tackle this issue, the National Institute for Occupational Safety and Health (NIOSH) has developed a standalone application, Design of Rib Support (DORS), for rib stability assessment and rib support design under development load. The rib support design in DORS starts with the rib support density, which is determined from the unsupported rib factor of safety (RibFOS). The relationship between rib support density and unsupported RibFOS was obtained from the collected field data. The objective of this research is to validate DORS rib support design by analyzing the extent to which the proposed design capability was utilized to support the coal ribs using numerical simulations. A series of numerical models with varying overburden depth and rib height were built and the ribs were supported with the DORS-recommended rib support design. The bolt load was analyzed under different conditions and the results show that bolt load varies with the overburden depth, the location of the bolt and bolt length. The load in the bolt(s) increases with the reduction in unsupported RibFOS. The bolt(s) start to yield when the unsupported RibFOS falls below a threshold value of 0.8 and secondary support is necessary.

Jun 25, 2024

By Timothy O’Rourke, Karrie Buxton, Chris Lynagh, Daniel Dobbels, Frederick Vincent

The Doan Valley Storage Tunnel Project in Cleveland Ohio was constructed to control Combined Sewer Overflows (CSOs). It is a complex system of three tunnels ranging from 8.5 to 18 feet in diameter with a total length of about 2.3 miles that was put into operation in mid-2021. The project lies within and below the cultural, educational, and medical hub of Cleveland, which presented unique design and construction challenges. This paper provides a case history of the design and construction, with particular attention given to lessons learned in devising a large tunnel system that can carry both dry and wet weather flows constructed in rock with limited cover, within a flood plain area and vibrant urban center

Dec 1, 2022

By Basilio Giurgola, Jeremiah M. Jezerski, Filippo Azzara, Federico Bonaiuti, Russell H. Lutch

The Northeast Boundary Tunnel Project consists of a 23 ft diameter, 27,000 ft long, CSO tunnel, multiple underground connections, and significant surface works within an urban corridor. The NEBT alignment depths range from 60 to 140 ft and includes seven shafts ranging in depth from 77 to 155 ft with diameters varying from about 19.5 to 56 ft, some as in-line connections and others required adits for connection to the main tunnel. This paper focuses on the design and construction of two major underground connections which are the First Street Connector Tunnel and the Mount Olivet Road Diversion Sewer.

Jun 13, 2023

By Bill A. Hancock

In Situ leaching for the recovery of uranium from low grade sandstone deposits is one of the newest technological advances in the mineral industry. It is rapidly developing into a commercially feasible mining system which has economic, environmental, and social advantages over conventional mining systems. Because of the current uranium shortage, development of In Situ leaching into a sophisticated system has gained new impetus. In Situ leaching will become an important mining technique in the future, which will greatly help to supply uranium for our nation's energy heeds. In this paper, I will be giving an overview of the merits of the system, as well as the technology, problems, and research in solution mining of uranium.

Jan 1, 1977

By K. A. Smith, X. Cheng

Introduction The separation of minerals from complex sulfide ores by flotation requires careful control of the surface chemical behaviors of the minerals constituting the ores. When the minerals in the ore are finely disseminated, extremely fine grinding is needed to liberate the minerals. Fine grinding is not only an energy-intensive operation, but also influences the flotation behaviors of liberated minerals. Steel balls are commonly used for grinding. Galvanic interactions occur not only between sulfide minerals and grinding media but also among the different sulfide minerals themselves. The electrochemical characteristics of chalcopyrite and pyrrhotite when they are independently coupled with steel grinding media and the relevance of these characteristics to the flotation behavior of these minerals have been exten¬sively studied (Cheng and Iwasaki, 1992: Li and Iwasaki, 1992). These studies dealt with reactions in two electrode combinations, simulating mineral-grinding medium and mineral-mineral interactions. In practice, however, it is more common to involve more than one sulfide mineral. In a study of a pyrite-pyrrhotite-mild steel system, Pozzo et al. (1989) provided evidence that a mineral having an intermediate potential could behave differently, depending on the condi¬tion of galvanic contact. This investigation was undertaken to study a chalcopyrite-pyrrhotite-mild steel system to gain better in¬sight into the mechanism of multiple galvanic interactions. A three-electrode system was chosen to simulate a typical copper sulfide ore. The sulfide minerals were represented by chalcopyrite and pyrrhotite. The grinding medium was rep¬resented by mild steel. The nature of galvanic interactions involving these minerals and grinding medium in an oxygen atmosphere was investigated in a three-electrode combina¬tion, and an attempt was made to relate the laboratory flotation results of pyrrhotite-chalcopyrite ores. Possible implications to the differential flotation of complex sulfide ores are discussed. Key words: Electrochemistry, Flotation, Sulfide ores Experimental The pyrrhotite (57.74% Fe, 0.09% Cu, 4.84% Ni and 36.54% S) sample was obtained from Falconbridge Ltd.'s Strathcona mine, Ontario, Canada, and the chalcopyrite (26.00% Cu, 28.57% Fe, 0.05% Ni and 31.52% S) sample came from Transvaal, South Africa. Mild steel (AISI 1020, 0.2% C) was chosen to represent grinding media. A conventional three-electrode cell was used in the elec¬trochemical measurements. The working, counter and refer¬ence electrodes were, respectively, sulfide minerals or mild steel, graphite rod and saturated calomel electrode (SCE, 0.245 V vs. standard hydrogen electrode). The exposed areas of the sulfide minerals and grinding medium electrodes were approximately the same (0.17 to 0.19 cm2). The preparation methods of working electrodes, the reagents used, the experi¬mental procedures and the instrumentation were the same as those described previously (Cheng and Iwasaki, 1992). Rest potentials of pyrrhotite, chalcopyrite and mild steel were measured individually in 0.05-M sodium sulfate solu¬tions. Combination potentials and galvanic currents of the sulfide minerals and grinding medium were measured in short-circuited two- and three-electrode systems. All poten¬tials in this study are quoted in volts with respect to the standard hydrogen electrode (SHE). To simulate the constantly abrading conditions in a ball mill, rest potentials, combination potentials and galvanic currents were also measured by rotating a porcelain ball against chalcopyrite, pyrrhotite and mild steel electrodes in

Jan 1, 2000

By WILLIAM M. CROSS, ALBERT ROMKES, BERNARDO MORENO BAQUEIRO SANSAO, Jon J. Kellar

In this research study, the interaction of particles with substrates of different roughness magnitude was investigated. Particle surface treatment, relative humidity (RH), and surface roughness levels were controlled in order to achieve separation of different particles by applying removal forces. Three different approaches to reproducibly roughen surfaces were used. Initially, glass disks were laser engraved to create a reproducible, controlled roughness substrate. However, the laser engraving method produced surface features that were much greater in scale than the particles. These scale differences were such that the substrates produced were not of value to this research. The second option investigated to induce reproducible substrate roughness was to scratch the glass disk using sandpapers of known grain size. A third approach to establish reproducible roughness was to use fine stainless-steel wire mesh substrates. In tests with sanded glass disks, the interfacial energy of plasma-cleaned (hydrophilic) glass beads had a high variation at 40% RH, showing non-uniformity of area of contact between particles and substrates. As the RH increased, it was expected that the interfacial energy of hydrophilic particles would increase, but this behavior was not observed. In addition, comparing the interfacial energy results of hydrophilic particles with hydrophobic particles, a region with significant interfacial energy difference was not identified. In the case of the stainless-steel mesh substrate, the mesh asperities and particle dimensions were comparable. Thus, the smaller particles had more area of contact with the substrate than the larger particles. For the plasma-cleaned (hydrophilic) beads, the recovery values had an average of 92.5% recovery when the RH was between 46 and 85%. For the hydrophobic beads, the average recovery was 19.0% when the RH was between 46 and 75%. Thus, the hydrophobic characteristic of the particle influenced its lower interaction with the mesh substrate. The difference in recovery can be exploited to achieve separation of particles based upon adhesive forces.

Nov 30, 2021

By Lake H. E.

The request to participate on your theme panel was accepted with some reluctance but indeed as an honor. My subject was outlined to cover 'Energy Resources - both nuclear and conventional' as related to your theme 'Minerals - Treasure Trove of the West'. This is indeed quite an order and I hope you will forgive me for concentrating mainly on the nuclear-uranium portion with brief references only to conventional fuels some of which will be covered in detail later in your conference. In regard to Uranium, I am speaking on the fringe of the area containing half the uranium reserves in your country and no doubt to many who are very conversant with knowledge of these resources. Nevertheless since our two countries have been very closely allied in both nuclear developments and uranium supplies I hope an exchange of information may be mutually beneficial. Concentration on the nuclear fuel resources is I hope understandable as nuclear energy is the coming source of power which will augment the rapid demand in the industrialized countries and provides hope for economic power in many of the more underdeveloped countries. The situation regarding conventional fuel resources is more widely known and their expanding future revolves around production cost reductions, research into diversified uses, plus more assurance of imports from countries less effected by international controversies determining export policies.

Jan 1, 1967