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By S. J. Ripke

To pelletize fine moist magnetite concentrate, a 40% water slurry must be dewatered to about 10% by filtration, before it can be agglomerated into pellets. Slurry pH, typically ranging from 8 to 11, gives the magnetite particle surface a strong negative charge and thus causes two adverse effects. First, this negative charge attracts calcium and magnesium cations, which strongly retard the effectiveness of the bentonite clay binder added during agglomeration. Second, a repulsive force created by the negative charge functions as a dispersant that reduces filtering production rates. Tests were conducted to remove these cations during filtration, by rinsing the moisture remaining in the filter cake with a small amount of water adjusted to pH 6 with HCl. Laboratory work was also conducted at Michigan Technological University (MTU) and at Cliff’s Mining Services Company (CMSC) to corroborate the plant tests. In some cases HCl caused filter bag blinding, therefore CO2was investigated to reduce pH. The CMSC lab tests showed that using carbon dioxide to reduce slurry pH from 7.6 to 7.0 improved filtering production rates by 11%. Plant-scale filtering rates were improved by 23.7% when carbon dioxide addition reduced the slurry pH from 8.6 to 6.7.

Jan 1, 2004

By L. G. Stolarczyk, R. C. Fry

In coal-bearing formations, seams are often bounded by sedimentary layers of mudstone, claystone or shale. When the electrical conductivity of the surrounding sediment layers is greater than the conductivity of the seam, a natural parallel plate waveguide forms in the strata. For frequencies below the AM broadcast band, the waveguide can be used for the transmission of electromagnetic (EM) waves. In a uniform seam, the primary wave travels in the coal layer along paths between a radiating antenna and a distant receiving antenna. The travel distance increases with seam height and the conductivity of the surrounding sediment layers. The distance decreases with increased coal conductivity. In Cretaceous western bituminous coal, the distance may exceed 549 m (1800 ft). Anomalous geologic disturbance zones such as faults, shear zones, paleochannels, sills and dikes significantly alter the values of EM wave propagation constants (attenuation and phase) expected in a uniform seam. In the neighborhood of an anomaly, EM wave energy is scattered (reflected and diffracted). Scattering creates secondary waves in the seam wave guide. A receiving antenna at a remote location in the coal seam can be used to measure the magnitude and phase of the EM wave at the end of the path. The measured data can be processed to determine the average value of the propagation constants along each path. Paths with anomalous propagation constants are used to locate and image geologic disturbance zones. Radio Imaging Method (RIM) instrumentation, survey procedures and data processing (tomography) algorithms have been developed to image geologic structure in advance of mining. The survey is conducted between gate roads of a longwall panel. Data processing constructs contours of constant attenuation rate (phase constant) across the plan view of the panel. In anomalous zones, the contours rapidly change with distance. The shape of the contour lines generates a visual image of the anomaly and suggests the type of anomalous condition to be expected in the coal seam. This paper briefly discusses the depositional environment and the formation of the imperfect waveguide in coal-bearing strata. The linkage between sedimentary geology and EM wave theory establishes an understanding of how the propagation constants depend on the anomalous geologic conditions. A case study compares in-mine geologic mapping with the tomographic image of a longwall panel.

Jan 1, 1991

By Yoginder P. Chugh

The Department of Energy is presently sponsoring the development of automated miner-bolter machines in an effort to increase production and productivity in the continuous room-and-pillar mining sections. This study is concerned with the production potential of these machines in three different mine layouts. The Underground Material Handling Simulation (UGMHS) computer model was utilized in the study. The effect of variables such as bolt installation delay, shuttle car capacity, and equipment availability on production are analyzed.

Jan 1, 1979

By Ralph D. Daley, Kevin E. Redinger

The production of coal/water fuel (CWF), a highly loaded mixture of finely ground coal, water, and chemical additives, presents a unique opportunity for significant ash and sulfur reduction through physical coal cleaning. Froth flotation can be integrated with the staged, wet, fine grinding inherent in the CWF production process. A laboratory scale research program was conducted to demonstrate the feasibility of a flexible, integrated coal cleaning/CWF process flowsheet. Performance of the conceptual flowsheet was examined for two coals of CWF commercial interest, Upper Freeport and Pittsburgh seam coals, from central and southwestern Pennsylvania, respectively. Several multi-stage coal flotation and reverse flotation circuits were evaluated. CWF was produced from the cleaned coal in each case at similar solids loadings and viscosities as observed for the raw coal. However, the ash loading and SO2 emission potential for each CWF had been significantly reduced.

Jan 1, 1988

By F. F. Aplan, V. Choudhry

This investigation is an exploratory study to evaluate a large number of potential pyrite depressants for use during coal flotation. Subsequently, the more promising reagents can be evaluated in detail. Several reagent categories (such as alkalis, lime, oxidizing agents, reducing agents, specific inorganic ions and dispersants) that were found to be effective pyrite depressants are discussed here. Other pyrite depressants will be discussed in Parts II and III.

Jan 1, 1993

By J. J. Carlson

Studies were carried out to determine whether filtration rate changes observed in an iron ore concentrator were due to variations in particle shape. It was confirmed that ores mined from different locations differed in filtration rates by as much as 60%. However, when image analysis was used to quantify the shapes of the individual particles in the filtration feed, it was found that the particle shapes showed almost no variation, and the shapes did not correlate with the filtration rate. It was also determined that the filtration rate variations were not caused by changes in particle size distribution. These results suggest that the differences in filtration rate are due to factors other than size and shape, such as surface chemistry.

Jan 1, 2008

By Fred N. Kissell, Robert J. Timko

Safe escape from coal mine fires continues to be a concern of the mining industry. The most life-threatening fires occur outby the working sections. Because stoppings always leak some air, an outby fire may in time cause intake escapeways to become contaminated with smoke and toxic gases. Smoke and gas infiltration into intake escapeways can be minimized by raising their air pressure over that of adjacent airways. This can be done by checking off the intake escapeway near the working face. The Bureau of Mines has investigated the use of a parachute stopping as a quick-erect check curtain during mine fires, and the concept has been tested in several mines. In every instance, when a parachute stopping was erected on the section, the intake pressure went up substantially. The pressure-raising effect of the parachute persisted for up to 1200 m (4000 ft) outby. Results indicate that checking off the intake escapeway may serve as a viable way to improve safety during mine fires.

Jan 1, 1991

By James Boyd

JAMES BOYD 29.1-STAFF-AND-LINE ORGANIZATION Industrial organizations are established primarily to coordinate the activities of many individuals working toward a specific goal. In mining, the goals can vary widely, and the skills necessary to reach them likewise will vary from operation to operation. It is essential to keep in mind the principal point that an organization embodies the necessary skills which supplement each other and achieve a given objective. Those who direct such an organization are grouped together as "management" and accept the responsibilities for the regulation, administration, supervision and guidance of the enterprise. Those who comprise the "administration" and have supervisory authority are referred to as the "executives." In the early days of mining it was common for one executive to exercise virtually complete control over the entire organization, and direct its operation from a central office. However, the science of management has advanced significantly since then. Mining organization administration now allocates increased authority and flexibility to those in direct-line responsibility, and organizes competent people in specialized fields to provide supervisors with guidance where it is needed in day-to-day operations. Few mining companies today are confined to one operation. Therefore, highly developed skills can be provided in the staff which assists management. This is known as staff-and-line organization, illustrated, in general, in Fig. 29-1. Each operation requires diverse skills for the carrying out of specific functions. The acquisition and training of those with such skills is an important operation in assembling organizations. An organization normally is modified to accommodate individuals rather than being a "hard and fast" mold into which people are fitted. The modern manager is inclined to organize to minimize central direction, with delegation to line executives, providing staff whose day-to-day operations, in cooperation with line executives, coordinate a continuing drive toward the organization's objectives. The staff officers, therefore, tend to become what could be described as parts of the president's brain, dealing with specific areas requiring certain skills. They do not necessarily direct operations, but watch them to be sure that the skills which they have themselves developed can be transmitted to line operations by persuasion rather than by direct authority. The elements of management requiring staff assignments are: 1. Planning, which, at staff level, is only a coordinating activity. Planning is done at all levels in the organization. 2. Engineering. 3. Finance. 4. Control. 5. Personnel and industrial relations, which set personnel policies, including salary plans and the means of handling relations with the unions. 6. Research, which, in a modern organization, is essential to progress and needs to be overseen at the top. 7. Legal staff to see that all operations of the company are provided with sound legal advice, and that the company's policies stay within the law.

Jan 1, 1973

By P. Venkatsubramanian, D. R. Maneval

An insufficient hydrologic data base exists for most large and small coal basins in Alaska owing to the lack of need in the past to collect data. The runoff process is insufficiently understood which is complicated by specifically northern phenomenon, and the lack of understanding of hydrologic relationships in permafrost environment. This paper presents an understanding of the hydrologic effects of frozen ground and presents methods by which the influence of surface mining upon the hydrologic balance can be analyzed.

Jan 1, 1987

By A. K. Sheik, W. G. Pariseau

A small underground mine in northern Idaho was used as an experimental facility for studying the role of water in the analysis of mine-opening stability. Laboratory test data, borehole measurements and geological mapping assisted in the construction of a coupled finite element model of the rock mass. The model was used to make quantitative estimates of rock stress, strain and displacement changes and to make estimates of the water pressure and flow velocity changes that occurred during historical mining. Stope cuts and wet fills were included in the analysis. The stability of the crown pillars between stopes was of particular interest. The relatively low effective stress and high rock-mass strength showed that water pressure changes were of no great consequence, which is in agreement with experience. The computational tools used in the analysis may be applied to other wet mines with appropriate changes to site-specific data.

Jan 1, 2002

By J. E. Brownhill

This paper does not deal with the typical start-up issues of equipment, production capacity or work force. This is a description of the challenges faced and the changes made by the project team to bring to fruition the reconstruction of Port Inland. Many honored traditions and norms had to be overturned to find the winning combination that provided the productivity, flexibility and cost necessary to survive in today's competitive minerals environment. This paper covers the innovation in terms of machinery, operations, and management philosophy that permitted the renovation and reopening of Port Inland as a commercial limestone producer in the spring of 1992. Port Inland, constructed by Inland Steel in 1930, operated as a captive source of metallurgical grade limestone for the steel industry until its closure in 1989. Located in the Upper Peninsula of Michigan on the north edge of Lake Michigan, the operations consist of a deep water port facility with crushing, screening and stockpile storage for 500,000 tons of finished product at the port. Ninety-nine percent of the stone is shipped via lake boat to ports within the Great Lakes. The operation is unique in that both metallurgical Dolomite and Limestone are produced on site. In 1930, Port Inland was at the fore front of technological advancement. It was the first major mining operation to use roller bearings and other equipment innovations. Over the 60 years of operation, Inland Steel placed emphasis on steel making technology and iron ore mining at the detriment of the limestone operation. By the early 80's, Port Inland was no longer a leading competitor. Inland Steel, unable or unwilling to spend the capital to modernize, closed the facility in the fall of 1989.

Jan 1, 1994

By N. L. Piret, R. J. Wesely, A. E. Melin, A. D. Zunkel

At the end of the sixties new iron precipitation techniques as jarosite, goethite or hematite brought about the new generation of electrolytic zinc plants, thereby terminating the multitude of existing neutral leach residue treatment schemes. Since the eighties, increasing environmental impact considerations urge the conversion of these contaminated waste generating precipitation processes to techniques which either produce environmentally acceptable residues or minimize their formation thereby generating iron-bearing byproducts. Technologies identified and economically assessed include the hematite process either suitably improved or with subsequent upgrading, the iron extraction process and the direct smelting of neutral leach residue to slag and fumed zinc oxide.

Jan 1, 1993

By Edgardo I. Cifuentes, Andrew L. Mular, Andrew Burkert

Experimental designs are data acquisition plans which, if followed exactly, will quickly provide process engineers with information to assess statistically the individual and joint influence of factors on responses to permit of rapid decision making. Methodology employed to construct data acquisition plans is described in some detail. In production environments, factorial designs are appropriate for most purposes. Use of two level factorials to make decisions is described for a grinding circuit.

Jan 1, 1991

By W. A. Cincilla, S. C. Tadolini

INTRODUCTION Resin bolting systems continue to gain popularity in underground coal mines in the United States, and their general success under a wide range of geological and operational conditions is well documented. In 1984, 36% of all bolts used were resin-grouted systems. However, many questions dealing with basic support mechanisms and the influence of various factors on bolt effectiveness in situ remain only partially answered. The Bureau of Mines' Denver Research Center conducted a major research project to investigate the influence of installation procedures on the effectiveness of resin-grouted roof bolts. The project consisted of two main studies: the first dealing with the contribution of bearing plates to the load-carrying capability of the bolt; the second examining the relationship between installed grout column and the anchorage capacity as measured by the standard pull-out test. Additionally, a finite-element computer model and other analytical and empirical techniques were applied to aid in the basic understanding of the test procedures and to examine the load transfer mechanism in resin-grouted bolts, which to date has not been comprehensively assessed. The plate study includes field test results from two mines (Fig. 1). At these test sites two behavioral parameters were measured: the actual loads that bearing plates were subjected to when installed in conjunction with full-column resin grouted bolts, and the roof movements generated by the applied loads. Results indicate that bearing plates are subjected to varying degrees of loading, which range from conventional installation pressures of 2.2 kN (500 lb), up to a measured load of 142.4 kN (32,000 lb) when the immediate roof is shifting and deforming. These measured loads indicate that the bearing plate is an integral part of the support system. Differential sag stations, installed to monitor roof displacements in the test sites, show the highest degrees of loading occur in conjunction with the largest amounts of movement. The column-length study addresses possible reductions in anchorage capacity of "full column" bolts. These reductions could result from such factors as the loss of grout to surrounding strata, or improper mixing of catalyst and resin. Field test sites were established at eleven mines located in major coal mining districts throughout the United States (Fig. 1). Four major roof-rock types were represented in the study: shale,

Jan 1, 1986

By Harrison R. Cooper

Composition data is needed as input for executing process control and management of particulate separation for flotation control. While requirements for composition data can be satisfied in many cases by manual sampling and analysis, automatic sampling and assay systems are now viewed as justified for all but the simplest or smallest processes. On-stream X-ray fluorescence analysis (XRFA) has satisfied requirements for the main portion of metalliferous sulfide ore flotation processes as XRFA technology evolved in reliability and sophistication from its beginnings in the late 1950's. In recent years, advanced on-stream analysis technologies have reached levels of development suitable for use in process control to increase efficiencies of important processes in mining and minerals industries such as coal fines flotation and industrial minerals beneficiation (particularly phosphate beneficiation) where XRFA methods have been inapplicable. Recent technical developments pertinent to use of advanced technologies as well as improvements to established on-stream composition analysis methods are discussed.

Jan 1, 1989

By Chinmoy Sarkar

Mining organizations have been trying to employ best practices at exploration, exploitation and processing level to increase productivity in the supply chain. Traditional techniques of cost control can no longer meet the ambitious target of mine managers. An integrated perspective of Mining Value Chain with enterprise-wide application of information technology (IT) ensures the ability of every mining processes to improve energy, land, capital and labour resource performance while continuing to cut costs and achieve profitability. IT offers enormous potential in mining industry at shaping entirely new opportunities to create value. This paper characterizes important entities of Mining Value Chain and attempts to provide a vision on how IT can transform the mindsets of industry managers addressing the needs of the customers.

Jan 1, 2002

By Richard A. Williams

The design, modelling and simulation of solid-liquid mixers remains one of the least advanced aspects of minerals processing, due to difficulties in quantifying complex slurry hydrodynamics from first principles, and in acquiring reliable experimental data for model verification and development. This contribution describes the application of electrical resistance tomography (ERT) for three dimensional imaging of the concentration of mineral particulates in a slurry mixer as a function of key process variables (particle size, impeller type, agitation speed). It is demonstrated how ERT can provide a wealth of detailed data to allow model development, which ultimately will lead to much improved design capabilities and the generation of mixing models which could reside within Particle Process Simulators. This principle is illustrated using descriptions of mixer behaviour based on an empirical approach, although the measurement methodology described is equally suited to development of computational fluid dynamics models, cellular models or design approaches based on artificial intelligence. The experimental data can be built into a visualisation data bank, which acts as a "process toolkit" by allowing a library of process responses to be catalogued. Hence these data can be accessed for the purposes of model development, equipment selection, optimisation of operating conditions or testing on-line control strategies.

Jan 1, 1995

By I. Iwasaki, K. A. Smith, X. Cheng

A cathodic decomposition model was examined for both pyrrhotite and chalcopyrite in an attempt to analyze the formation of surface coatings in deoxygenated solutions at natural, near neutral pH. Combination potentials established between the mineral-grinding media pair were simulated by applying a potential of -0.455 V (vs. a standard hydrogen electrode) either to a pyrrhotite or to a chalcopyrite electrode. Chronoamperometry was used to study the polarization behaviors and alteration of mineral surfaces through cathodic processes. The kinetic parameters of cathodic decomposition of pyrrhotite and chalcopyrite were determined and compared. It was concluded that pyrrhotite decomposed faster than chalcopyrite in near-neutral pH solutions. Both minerals were then covered by a film consist¬ing mainly of iron hydroxides, which adversely affected their flotation.

Jan 1, 1999

By Alan C. Noble

Ore reserve estimation is a multi- disciplinary process involving not only tonnage and grade estimation (resource estimation), but also consideration of technical and legal aspects such as mining the deposit, beneficiating the ores, and selling the product. This paper provides a background to under- standing resource estimation including geologic modelling, manual estimation methods, conventional computer methods. and geostatistical methods. Mine planning, metallurgical studies, legal/environmental, and marketing considerations are also discussed as they relate to estimating ore reserves.

Jan 1, 1991

By P. K. Mululi, T. M. Yegulalp

The number and type of trucks and shovels used are two important factors in determining the optimal design parameters of an open-pit mining system. The characteristics of the arrival and service-time distributions of the trucks determine the performance measures of a truck-shovel system when it is modeled as a closed queuing network. In all of the previous analytical queuing studies of truck-shovel systems, trucks are assumed to be identical with respect to their arrival and service-time distributions. This assumption, although desirable for reducing computational difficulties, causes either underestimation or overestimation of the performance measures, depending on the number and types of equipment used in the model. The relative error in performance measures could be significant when the number of different types of trucks and shovels is large. In this paper, an analytical method is proposed to model the truck-shovel system as a multiple-class closed queuing network. This approach provides the capability of estimating system performance measures for planning purposes when the truck fleet is not necessarily composed of identical trucks. An example of truck-shovel systems is presented to show how the incorporation of different types of trucks affects performance measures.

Jan 1, 1998