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By Ralph M. Foecking

The disposal of the phosphate slimes produced by Florida beneficiation operations is perhaps the biggest single problem of the phosphate mining industry. This is an old problem which has not been solved and which is becoming increasingly severe. In a typical phosphate mining operation, the phosphate rock mined is initmately mixed with sand and clay, constituting what is known as matrix. During the beneficiation, the clay and other fine materials are separated usually at -150 mesh, and washed from the phosphate rock in a form of diluted slurry known as phosphate slimes. The quantity of slimes solids and their composition vary considerably with the location but usually represent from 25 to 35% of the ore mined. Because of the affinity that clays have for water, large volumes of water are required to separate the granular material in the matrix forming a dilute slime suspension (1.5 to 3% solids) of colloidal material, which settles very slowly, and thus requires immense impounding areas, which never becomes totally usable land. These ponds also contain about 25 to 35% of the total P205 values mined. The magnitude of the problem represented by the slimes can be appreciated better if we realize that there are around

Jan 1, 1971

By A. Noble

"Froth flotation circuits are widely used throughout the mineral processing industry for the concentration of fine particles. It had been estimated that nearly 2 Gt (2.2 billion st) of ores are treated globally each year using this versatile separation process (Fuerstenau, 1999). Due to the high feed tonnage, a large economic incentive exists for flotation plant operators to optimize the performance of this critical processing circuit. Prior to the 1950s, the optimization of flotation circuits primarily involved the manual adjustment of operating variables based on visual observation and sporadic sampling (Lynch, Harbort and Nelson, 2010). During the next several decades, however, the advent of improved on-line instrumentation coupled with the rapid development of high-speed microprocessors allowed the industry to develop more advanced control systems that could quickly adjust operational parameters in response to disturbances in ore characteristics and plant flows. These early online controls typically involved feedback loops designed to stabilize cell performance through the automatic manipulation of process variables such as pulp levels, gas rates and chemical dosages. The set-points for these controllers were often set by plant operators based on one or more operator objectives, such as maximizing throughput, recovery or grade. More recently, these regulatory controllers have been interfaced with high-level data display and management systems that provide operators with the ability to better optimize flotation plant performance based on mathematical models and rule-based algorithms (Greet, 2010).While tremendous strides have been made during the past several decades, even the most modern flotation plants are still faced with the long-standing question: “What are we trying to optimize?” From an operator perspective, some common responses include “Maximize tonnage of saleable concentrate” or “Maximize metals recovery at a customer-specified market grade.” These replies may or may not reflect those of management, who often focus on economic goals such as “Maximize profits for each operational unit” or “Maximize rate of return for all corporate assets.” Unfortunately, these high-level objective statements do not always translate well into practice due to the disconnect between plant operating protocols and product value. Attempts have been made by industry to overcome this issue using various types of optimization routines such as linear programming or other optimization engines. While this approach does have some merit, these blind routines require considerable input data and interpretational expertise and provide little or no fundamental insight that can be used to drive improvements in concentrator performance."

Feb 1, 2017

By R. A. Cummings

From before the turn of the century until as recently as the 1950s, relatively shallow coal reserves near the margins of the Illinois Basin were extracted by room- and pillar methods. Subsequent development has, in many cases, extended onto ground with high subsidence potential. The same state of affairs exists in many other historical coal mining districts, as well as in Illinois. Pit subsidence in Illinois is particularly common in the towns of Streator, Carterville, and Herrin, although there are others. Pit subsidence is characterized by distinct circular or oval depressions and normally is associated with shallow mining and thick soil relative to the thickness of rock.

Jan 1, 1985

By William M. Warren

Recent sinkhole activity in carbonate terranes of Alabama has resulted in damage to transportation lines, structures, utility lines, and property in general. Active sinkhole development and subsidence has been well documented in Alabama, Florida, Pennsylvania, and South Africa. An excellent example of the potential danger resulting from this activity is the spectacular collapse under a South African gold ore crusher plant that resulted in the death of 29 men in 1962. Due to the severity of the problem in certain localized areas in Alabama, a detailed investigation is being undertaken by the Geological Survey of Alabama and the U. S. Geological Survey. One of the most promising techniques is the application of aerial photography and thermal infrared imagery. Conventional and modern remote-sensing techniques are being used in Alabama to locate and define areas of sinkhole activity and to determine which areas are most prone to its occurrence.

Jan 1, 1975

By Hossein Kazemi

This article is a review of fluid flow and mass transport in fractured rocks. The topics include: single-phase and multiple- phase flow theory, formation productivity or injectivity improvement by artificial fracturing, and mass transport associated with fracture acidizing. Possible extension and application of such ideas to in situ mining in fractured rocks are presented.

Jan 1, 1974

By Allen D. Graham

The coal industry in South Africa is briefly outlined. Test- work carried out on bulk samples of coal in the laboratory and used in the design of the Van Dyks Drift washery are described. Factors affecting the selection of equipment and the designed capacity of the plant are discussed. A description of the crushing plant, washery and load out section is given together with performance data obtained in the final acceptance tests. New features incorporated in the Van Dyks Drift plant and in more recent plants of the Group are outlined.

Jan 1, 1982

By Yutaka Mochida

OUTLINE Beginning in 1946, a careful geological survey was made of the Tsugaru Straits. In 1964, excavation of the exploratory tunnels were started to observe the characteristics of faults and rock formation directly, and to study construction methods of excavation and sealing water inflow. In March 1971, the investigation stages were over, and in April 1971, the construction project was authorized from the government. The geological features in the straits may be divided into three broad classes. One third consists of andesite on Honshu side. The other two thirds consists of tuff. The middle of the straits consists of tuff, so-called Kuromatsunai-layers. On Hokkaido side, it consists of tuff, called as Kunnui-layers. There are nine noteworthy faults on the route. Prior to the excavation of the main tunnel, the horizontal pilot tunnels and service tunnels are made. Exploratory borings are taken to confirm the geological conditions and the presence of gushing water. Groutings for sealing water inflow are carried out when necessary. In geologically bad conditioned sections such as disintegrated or fractured zones, special methods are applied. In geologically good zones, the tunnels are bored through using the same methods as for a mountain tunnel driving. The pilot tunnel being constructed at the sea bottom is under direct control of the Japan Railway Construction Public Corporation. The service tunnel and the main tunnel are being excavated by contractors.

Jan 1, 1981

By E. Grygiel, J. Haynes, T. McNider

Jim Walter Resources Blue Creek No. 3 Mine was opened in one of the most gassy coal beds in the United States. Although face ventilation requirements exceeded 14,000 cfm (6 .6m3/s) air, continuous miner sections experienced an unacceptable frequency of frictional ignitions. Modifications offered primarily by the U. S. Bureau of Mines such as diffuser fans, water spray fans, and slow speed cutting motors were used with little success. However, laboratory tests conducted at the U. S. Bureau of Mines indicated that an increase in bit attack angle from 50° to 55°-57° significantly reduced the chances of the bit causing a frictional ignition. An experimental miner drum was built using this concept coupled with a new bit designed by the Bureau and manufactured by Hughes Tool Company that better protected the bit steel shank with a carbide cap. It was installed on a continuous miner and placed in an area of the mine prone to ignitions. 50,000 tons (45,500 metric tons) of coal were cut without a frictional ignition. When the miner was withdrawn for rebuild and a machine with an unmodified cutting drum placed in service, two ignitions occurred before 10,000 tons (9,100 metric tons) were mined. Other machines have been rebuilt and are in service, and to date none have been known to cause an ignition.

Jan 1, 1987

By Nancy J. Wheatley

I. INTRODUCTION The Massachusetts Water Resources Authority (MWRA) is a regional water and sewerage authority which provides wholesale water and sewer services to the Metropolitan Boston area. The MWRA was created by the Massachusetts Legislature as an independent authority in 1985 following the filing of a lawsuit in federal court to correct the pollution of Boston Harbor resulting from inadequate and inadequately maintained sewerage facilities. Immediately upon its creation, the MWRA began to tackle treatment plant issues, including addressing the need for a secondary treatment plant, planning for ceasing ocean discharging of sludge, and making interim repairs to the existing, antiquated treatment plants. The MWRA's initial activities led to a court-ordered schedule for construction of a single new primary and secondary treatment facility, for development of sludge management plan focussed principally on reuse, and for completion of a short term program of repairs to existing facilities. Once a schedule for completing these activities had been negotiated, the U.S. Environmental Protection Agency (EPA), a plaintiff in the federal court case, asked that the MWRA take "responsibility" for controlling discharges from combined sewer overflows (CSOs) within its service area. Combined sewers (sewers in which both sanitary sewage and storm water runoff are carried in a single pipe) presently discharge over 10 billion gallons of untreated wastewater into Boston Harbor and its [ ]

Jan 1, 1991

By J. A. G. Llerena, J. Sattarvand

Tailings dam failures have been occurring in recent years. They are considered more vulnerable than hydraulic dams due to the lack of regulations on specific design criteria, and stability requirements regarding monitoring during the construction and maintenance process. Thus, monitoring the dam is essential to know the dam's existing state and ensure its safety. One of the reasons tailings storage facilities fail is slope instability caused by moisture content. A relationship does exist between moisture content and surface strength, early detection of seepage would help to assess the physical condition of the dam. Moreover, to cover the tailings dam area in an efficient way Unmanned Aerial Vehicles (UAVs) are suitable because of their versatility and high-resolution data acquisition. Mounted with a high-resolution RGB camera, and thermal, or hyperspectral sensors UAVs can acquire good quality images that combined with image analysis and machine learning algorithms yield a good estimate of soil moisture.

Feb 1, 2023

By F. W. Petersen

Slurry reactors are being used extensively throughout the chemical, biochemical and mineral processing industries. This paper describes the interaction between fine ore particles and granular porous adsorbents such as activated carbon and ion-exchange resins in a stirred tank reactor. Gold and silver cyanides were used as adsorbates to detect changes in the mass transfer characteristics of the adsorbents, which were ashed to determine the loading of ore particles. A simple kinetic model incorporating film diffusion, intrapanicle diffusion ~d the adsorption equilibrium, was used to interpret kinetic data and to estimate the effect of slurry conditions on the diffusion parameters. It was observed that the equilibrium loading of fines in the adsorbents was independent of their concentration in the slurry. Furthermore, the presence of these panicles inside an adsorbent decreases the effective diffusion of gold or silver cyanides into the adsorbent matrix. When fine suspended solids are present in the reactor, a decrease in the effective availability of the superficial surface of the pre-saturated adsorbent panicles for mass transfer from the liquid phase was observed. This newly defined surface availability factor was dependent on the concentration, panicle size, and the zeta potential of the fine particles in suspension.

Jan 1, 1993

By R. L. Grayson

Conventional mine safety wisdom states that "the most efficient mines are also the safest." Since the 1980s, small mines (and contractors) have been targeted as the most dangerous ones because of their fatality records. Statistical testing of 1993 West Virginia safety and production data indicated that the most efficient WV mines were not the safest ones, considering correlations between the severity measure and tons per employee-hour, except for very small mines. This paper will present the results of an extended analysis of WV mine safety using 1993 and 1996 data, concluding with the method used to suggest current priorities for focusing interventions.

Jan 1, 1998

By Cyrus W. Field

Metalliferous sediments constitute an important component of the sedimentary veneer that overlies basaltic oceanic crust of the Nazca Plate and elsewhere. Although first collected more than one century ago near the East Pacific Rise during the Challenger Expedition and recognized for their anomalously high content of Fe and Mn, occurring as very fine-grained, yellow-orange, oxides, hydroxides, and oxyhydroxides, it was not until the more detailed studies of Bostrom and Peterson (1966) that their geologic significance and concentrations of other transition metals were fully appreciated. The Nazca Plate is a dynamic lithospheric unit bordered by the Peru-Chile trench and the East Pacific Rise to the east and west, and by the Galapagos Rift and the Chile Rise to the north and south (Fig. 1). Samples employed in this study were taken from piston core recovered from the Nazca Plate (Fig. 2), D. S. D. P. drill core from the northeast Pacific (Dymond and others, 1973), ferromanganese nodules from dredge-haul s at several locations, and from hydrothermal mineral deposits of the Andes. Our efforts have been largely sponsored by the National Science Foundation through its International Decade of Ocean Exploration Pro- gram. The metalliferous fraction of these sediments is widespread, but generally small. Sedimentation is dominated by biogenic silica in the equatorial latitudes, terrigenous debris adjacent to the South American Continent, and by biogenic carbonate elsewhere, except at depths below 3500 m in the central and northwest parts of the Nazca Plate near the East Pacific Rise. Contributions of these distinctive sediment types are shown by the distributions of Si02, A1203, and CaC03 given in Figure 3.

Jan 1, 1982

By Raymond L. Lowrie

Deregulation, as authorized by the Energy Policy Act of 1992 (PL102-486) allows free-market competition in the electric-utility industry. As the act unfolds, though, uncertainties abound about the type, degree and direction of impacts throughout the affected economy — from fuel suppliers to electricity generators and from power distributors to energy consumers. Instead of having a familiar base of captive customers and electricity prices fixed by negotiation with state public utility commissions, utility companies are preparing for open, free-market competition. They are looking at all areas, including fuel supply, to cut costs to remain competitive. Humorous anecdotes are told about utility companies shunning insiders for senior executive positions. Instead, they are opting for people from the telephone or other industries with deregulation experience. And there are light-hearted stories about a trend away from traditional electric-company names, such as the name of a city or state followed by Edison or Power and Light, to space-age names, such as Ameren, Entergy, Illinova or Unicom. No one wants to be left behind or be perceived to be left behind.

Jan 1, 1996

By D. E. Nash

Environmental compliance programs for mining companies are not only important management tools, but can deflect serious civil and criminal penalties if violations of environmental laws do occur. The paper discusses the legal foundation for such programs and their basic structure.

Jan 1, 2001

By K. V. Raj, T. Bhowmick

"The control of fugitive dust in high-latitude openpit mines is challenging due to unique atmospheric phenomena resulting in complicated flow regimes as well as atmospheric inversion due to the lack of adequate insolation during prolonged winter seasons. In this study, two idealized (one conical and one trapezoidal) three-dimensional openpit mine geometries were simulated for different seasonal conditions using a computational-fluid-dynamics package from Software Cradle. The airflow was solved by Reynolds-averaged Navier-Stokes equations using the standard kappa-epsilon turbulence model. The concept of particle tracking was used to predict the flow patterns of dust particles. For various climatic conditions and two different pit geometries, fugitive dust particles varying in size, from PM0.1 to PM10, and concentration were generated at various locations and dispersed by the airflows inside the openpit mine. The amount and location of dust particles inside the pit were reported at various time intervals. In the summer season, airborne dust particles were quickly transported outside the openpit domain. In the winter season, however, the development of atmospheric inversion significantly affected the amount of dust retention inside the openpit domain. IntroductionThe computational-fluid-dynamics (CFD) modeling of openpit mines is challenging. In a recent paper (2015), we presented different constraints and challenges in developing a three-dimensional CFD model. In order to obtain realistic results from a simulation, however, appropriate values of various inputs are required. The simulation results of a three-dimensional nonhydrostatic model by Shi et al. (2000) showed that both the mechanical and thermal forces are important mechanisms, controlling the development of the atmosphere inside an openpit mine. Alvarez et al. (2007) used a CFD model for predicting dust dispersions in a medium-sized limestone quarry, and presented several iso-surfaces of varying dust concentrations using ANSYS CFX. A similar study by Torno et al. (2010) introduced a more sophisticated parameterization of the dust sources. Flores et al. (2014) used an OpenFOAM CFD simulation package to simulate and predict pollutant dispersion in an idealized and an actual openpit mine in Chile with an intense insolation condition. The model was simulated for three different conditions: (1) air-advection (10 m/s, or 33 ft/ sec)-driven mechanical turbulence, (2) surface-heat-flux (240 W/m2, or 76 Btu/ ft2-h)-driven thermal buoyancy and (3) both air-advection- and surfaceheat- flux-driven conditions. The results of the simulations showed that the buoyant currents contribute to the removal of a large percentage of the dust particles. The buoyant currents modify the purely mechanical-turbulence- induced flow pattern and reduce the particle residence time, commonly observed in a purely mechanical turbulent flow (nonbuoyant case)."

Jan 1, 2015

By A. J. Basu

Geotechnical design plays a key role in mine design. I A proper geotechnical design provides a safe working environment and facilitates efficient mining operation. There are mainly three design approaches I) judgmental, based on observational and experiential facts, 2) empirical, based on empirical design formulae, and 3) analytical, incorporating numerical analysis. Most design applications are based on the design methods one and two as mentioned earlier. However, complexities arise in deep underground mining operations and deep open pit mines. These complexities and difficult geological environment introduce more uncertainties and simple empirical formulae would not be adequate as a design tool. These situations require numerical modelling and analysis of the design problems including interpretation of the results obtained from the analysis. There are several tools available for performing the numerical modelling and analysis. A brief review of the available tools was addressed earlier (Basu and Kuruppu, 1995). The authors selected ANSYS (a general purpose finite element analysis tool) for use in mining geomechanics and geotechnical design. This paper includes several examples demonstrating the applicability of this software in designing structures applicable to mining geomechnics. The authors hope that the design examples will demonstrate the use of the numerical modelling and analysis application in excavation design.

Jan 1, 1996

By J. C. Stankus

Many coal seams are associated with soft floor strata and during mine development if coal pillars are not properly designed, floor heave occurs and causes interruption of coal production. In the severe cases, the section or mine is abandoned. One of the methods for controlling floor heave is floor bolting. This paper describes the demonstration of floor bolting methods in a West Virginia coal mine. Three methods were used: (1) vertical full resin bolting, (2) floor truss bolting, and (3) floor truss bolting plus a floor cut at the center of the entry. The design of each method and the experimental results are discussed in detail.

Jan 1, 1993

By J. A. Murray

Maintaining satisfactory air quality in electrowinning tankhouses is problematic and costly, particularly as plant operating current densities have increased. Conventional approaches have not proved completely effective. These include the use of beads, hollow spheres, surfactants and coalescer devices. They require powerful ventilation systems to be installed. As workplace and environmental regulations become more stringent, containment of the acid mist at its source is more attractive. An electrode cap system based on this approach has been developed and tested in two commercial copper electrowinning tankhouses.

Jan 1, 1996

By C. L. Wilsey, K. M. Oakes, W. J. Reich, M. J. Protani

The time frame required to complete the National Environmental Policy Act (NEPA) process for a new mine, or for the expansion of an existing mine, can range between 9 months to 24 months, or more. The time frame will vary depending on whether an Environmental Assessment (EA) or an Environmental Impact Statement (EIS) will be completed. Completing properly designed baseline studies to collect natural resource data to support the EA or EIS prior to the start of the NEPA process can shorten this time frame. The two year natural resource baseline study completed by Homestake Mining Company for the Ruby Hill Mine, located in Eureka County, Nevada will be used as the case study to describe how properly designed and executed natural resource baseline studies streamlined the NEPA process.

Jan 1, 2001