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By George Wilson

As the economic and environmental attractiveness of conveying coal and ore slurries by pipeline increases, greater attention has been given to designing and selecting components for these pipeline systems. Pumps are one critical element in pipelining. Pumping slurries is a particularly arduous task, calling for special design and construction. The first article in this two-part series describes some factors to consider when selecting pumps to resist abrasive wear.

Jan 9, 1981

By D. V. Ramani, M. M. Kissel, M. T. Ityokumbul

Experiments were carried out to determine the efficacy of bubble column flocculation. An acid-base neutralization method was used to determine the mixing time in a 0.064- by 1.5-m bubble column equipped with a Mottporous sparger. The mixing times decreased as the tracer injection point approached the gas sparger. Preliminary flocculation experiments on two clay samples were carried out. The effects of frother addition and airflow rate are presented and discussed.

Jan 1, 2000

By T. Altman

Using theory of network planning together with graph theory, an algorithm is presented that creates canonical diagrams for mine ventilation networks (M VN). The data generated by the algorithm is used in the construction and plotting phases of a program that automatically plots the canonical diagrams, which can then be used for further studies of a given MVN.

Jan 1, 1988

By Anthony Busigin, Charlett Busigin, Colin R. Phillips

For the purposes of measurement and dosimetry of airborne radon daughters in uranium mines and elsewhere, it is important to understand their physicochemical state. This work deals with the chemical fate of 218Po in air. Extensive experiments were performed to determine the rate of neutralization, diffusion coefficient and fraction born charged of 218Po in air. The experiments were performed in a specially constructed apparatus of well-defined geometry. Careful control of experimental conditions made it possible to obtain more precise and detailed quantitative data than previously possible.

Jan 1, 1981

By G. Pan

A geostatistical approach is proposed for the design of infill drilling programs. The method consists of the following four major steps: developing geological favorability models, delineating mineralization and ore envelopes, classifying resource potentials, and designing infill drilling patterns. Geological modeling develops the permissible geological zones in which infill drilling is designed. Modeling mineralization and ore envelopes establishes criteria on the potential blocks to be drilled. The blocks that are included within the ore envelopes are considered in the infill drilling. The following four types of resource potentials are used in this analysis: measured, indicated, possible and barren. Blocks in the indicated category are the top targets to be confirmed in infill drilling. Blocks of possible resources may be considered exploration targets. The algorithms involved in the analysis include indicator favorability analysis, indicator kriging and ordinary kriging. A case study on a gold deposit of the Carlin type is presented to demonstrate the methodology. The deposit was originally delineated by a sparse drilling program with about 230ft of average spacing. The infill drilling design, based on the new method, suggests a significant reduction on the number of holes from a regular-grid infill drilling pattern.

Jan 1, 1996

By A. Mahtab, S. Xu, P. Grasso, B. J. Fu

The large population base, complex geology of the large land mass, and notable commercial activity have accelerated the development of underground construction market in China. The projected lengths of underground openings per year in the various sectors are: hydro-tunnels, 180 km; coal mine entries, 40 km; transport-tunnels, 300+ km. An example of the mega projects (being planned by the Government) is the water supply scheme for connecting Yangtze river to Yellow river involving 131 km of water tunnels with a diameter of 8-10m. Several large projects are highlighted in the paper with reference to the schemes for generating hydro-power, mining of coal and minerals, and constructing transportation networks. The related problems of construction and geomechanics are outlined.

Jan 1, 1995

By Fernando Concha, Arturo Barrientos

The flow in a hydrocyclone is divided into a boundary layer around the walls, an exterior inviscid flow and an air core in the center of the equipment. The boundary layer flow over the lateral walls is associated with the short circuit of particles to the underflow, while the boundary layer over the top of the hydrocyclone and the outer part of the vortex finder tube is related to the short circuit of particles to the overflow. Classification takes place in the exterior flow. The model can be validated with pilot or industrial data and simulates the performance of hydrocyclones in a wide range of design and operating variables.

Jan 1, 1992

By C. Garcia, C. L. Lin

Characterization and analysis of multiphase particles and/or particulate systems (such as the packed particle bed) are of great technological importance for mineral processing applications. In general the performance of these applications depends on the statistical characteristics of particle microstructures, such as composition distribution, surface exposure of mineral grains, pore network structure, etc. For continued technological progress in the field of multiphase particulate processes, the need for quantitative spatial analysis of multiphase particles in three dimensions has increased sign6cantly. Such quantitative information must be accurate enough that the measured values can be used as parameters for simulation models, process design procedures, and control strategies. Modern 3D image-acquisition techniques, such as X-ray microtomography (XMT), offer a unique imaging capability that can produce high-resolution (a few micrometers) three-dimensional images of the internal structure of multiphase particulate samples. These three-dimensional image data present new challenges for image analysis, image processing, and visualization. Furthermore, important issues should focus on how to use the 3D information and derive new insights into the improvement, design, and operation of mineral processing processes. In this paper, utilization of XMT for characterization and analysis of leaching process involving multiphase particulate system is discussed.

Jan 1, 2005

By V. Dezelic, D. B. Apel

This paper describes the results of laboratory and field experiments conducted to determine the applicability of Ground Penetrating Radar (GPR) for the assessment of the strata thickness and for the identification of separation between bedding planes in stratified rocks. The knowledge about the extent of such separation in the roof layers and information about roof lithology can be used to determine the roof support requirements for underground mines where stratified rocks are present. The laboratory and field experiments were conducted at the Rock Mechanics Laboratory and the Experimental Mine at the University of Missouri-Rolla. The 1.5 GHz high resolution, shallow depth GPR antenna was used for all of the experiments.

Jan 1, 2004

By Donald L. Meredith, Jeffrey Harris, Donald A. Stanley

Principal Components Analysis (PCA) is a versatile, multivariate statistical method that the Bureau of Mines is applying to mineral processing data to achieve data simplification and pattern recognition. The principal components are obtained from an eigenanalysis of the data matrix. To achieve data simplification PCA replaces a larger number of measured variables with a smaller set of principal components and at the same time removes a significant amount of experimental error. Data simplification and error reduction make PCA useful in process control. Plots of the individual principal components form the basis of a pattern recognition technique that allows detection of significant variations in the structure of the data. These applications of PCA are illustrated with appropriate mineral processing data.

Jan 1, 1993

A form of column flotation cell is described in which the contact between the feed and the air stream is made in a mixing device at the top of a vertical downcomer. The air-liquid mixture flows downward to discharge into a shallow pool of pulp in the bottom of a short cylindrical column. The bubbles disengage and rise to the top of the column to overflow into a concentrate launder, while the tails are discharged from the bottom of the vessel. The main advantages of the device described are that the overall height of the column is reduced to about 1 m (3 ft), and the column can be self-inducing with respect to the air supply. Experimental results are given from tests on a feed stream to a conventional zinc cleaner circuit. Using wash water to reduce gangue entrainment, the column gave high concentrate grades and high recoveries.

Jan 1, 1987

This paper discusses the type of scaling operations presently in use in underground mines. It defines a scaling factor that is expressed as the area necessary to scale to extract 1 t (1.1 st) of ore. The problems associated with conventional scaling methods are discussed as well as recent developments in mechanized hand-held scaling de- vices and methods of loose detection. The elements of the scaling process are further analyzed. The conception and design of a mechanized scaling device, developed at Universite' Laval is also described. The results of field tests conducted in Quebec hard rock mines are presented. The experimental findings show that the mechanized hand-held scaling device shows potential in improving the productivity and safety of underground mining operations.

Jan 1, 1996

By Yuanping Chen, Yihui Zhao, Yunhe Hong

It is important to study the methane transport phenomenon in a longwall panel under descentional ventilation conditions. The gob area is divided into a number of rectangular percolating elements, each of which is connected with its neighbors by leakage passages, so that a network can be formed. Using the mechanics of porous media fluid flow, the mathematical model of air and gas flows can be established. Based on the existing ground pressure theories, the inhomogeneous porosity of the porous media in the gob can be given. Through computer simulation it is found that air pressure and temperature are functions of position. Air density, viscosity, and natural ventilation pressure are functions of temperature, pressure and methane concentration. It is also found that the resistance varies with air density and viscosity. Finally, the calculation results are given to show the differences between ascentional and descentional ventilation methods.

Jan 1, 1991

By Andrew H. Merritt

INTRODUCTION The prediction of the engineering behavior of a rock mass depends upon the systematic analyses of the results of an exploration program, and upon the recognition of the significant rock properties in the early stages of excavation. The variations in rock properties in different geologic terrains and the state of the geotechnical art preclude complete success in the former case, and we therefore must rely heavily on the experience gained in the latter phase. The geotechnical information obtained from these two phases is only of value to the design engineer when applied to the rock behavior during excavation and subsequent plant operation. Pertinent questions which must be answered include: how does the joint orientation and frequency effect tunnel support and overall cavern stability; how does the depth of surficial soil or weathering effect foundations or slope stability for portal cuts; are there permeable zones within the rock mass that could lead to leakage problems around penstocks and is the material in these zones soluble or likely to pipe in the long term; and does the proposed engineering structure fit the terrain, or will it inevitably lead to problems requiring extensive remedial treatment. During the early stages of construction there are two types of geotechnical information required; actual rock behavior with respect to the original design assumptions,

Jan 1, 1997

By Stephen D. Schwochow

Aggregate producers nationwide well recognize the numerous problems often faced in securing local approval to open and operate new gravel pits and rock quarries. Similar problems are faced in Colorado, but this region also presents certain political, social, and geological complexities that have become particularly troublesome in the last 10 years. The gravity of the local permitting dilemma can be related directly to the worsening supply-demand imbalance for aggregates in the state's most populated area, the Front Range urban corridor, particularly the Denver metropolitan area. The drive to develop crushed-rock reserves to supplement dwindling alluvial supplies and to meet increasing regional growth demands was somewhat predictable but perhaps more a "last resort" alternative forced onto producers by a hesitant and often apathetic government.

Jan 1, 1982

By R. P. Killmeyer, R. E. Hucko, P. S. Jacobsen

Cleaning of three coals from the eastern US was tested by five selective agglomeration processes and one selective flocculation process. The coals and processes are described, and the results are reported and compared. Two of the processes, which ground the coal to the finest volume mean diameter, met the stringent test program quality specifications.

Jan 1, 1991

By E. Topuz, M. J. McPherson, I. M. Konduri

The research is carried out to investigate the flow mechanics and effectiveness of face ventilation using induction fans, as an effort to provide a more efficient alternative to conventional auxiliary duct or brattice ventilation systems. The induction effects and plume longevity of fluid jets are being studied with the help of a plexi-glass model, using water as the fluid medium and creating a system that is dynamically similar to the flow in mine headings. This scaled model represents a typical 1.5m x 6m x 25m heading connecting to a crosscut. Reynolds Number criteria are used to obtain dynamic similarity of the flow in the designed model to simulate real mining conditions. The role of various parameters such as nozzle position in three dimensions, airway roughness, nozzle geometry, and flow rate in the jet are studied. During the laboratory tests, flow visualization techniques, coupled with still and video photography, were employed to identify the flow patterns. The results indicate that in typical coal mine headings, jet fans can produce effective face ventilation for distance up to 30 meters.

Jan 1, 1995

By Gene M. Handel

Today the world is heavily dependent on petroleum for its energy. In the United States, over 75% of the primary energy used comes from petroleum. Other developed countries are similar. The less developed countries have a lower dependence on petroleum just as the United States did through the early 20th Century. However, these less-developed countries look upon petroleum as one of the primary energy sources for the economic growth required to improve their standard of living. So everyone considers petroleum an essential ingredient in the recipe for the good life. But there is a substantial problem with this recipe, and it is finally getting general recognition. Petroleum is a finite resource, and the world is using it up at a rapid, accelerating rate. Though it won't be exhausted for many decades, the early warnings of ultimate limits have already appeared. The suppliers of the incremental production in the Middle East have threatened to restrict increases in their production rates. And, of course, the short term embargo of four years ago clearly demonstrated the economic impact of reduced access to petroleum as a primary source of energy. World petroleum production will probably peak in. 10 to 15 years and then start declining. When that happens, economics--the allocation of scarce products (also known as the dismal science for obvious reasons)--indicates that the price of petroleum will escalate in real terms. So that's the situation today. We have a serious and growing problem facing us that could substantially alter the quality of our life over the next 25 years. Recognition that the society may face a period of lowered expectations after a long period of upward mobility will be a painful experience, but it is certainly not the moral equivalent of war. And, besides, we have time to take positive actions to avert the most serious consequences. When we consider alternate energy sources, the possibilities are almost endless: coal, oil shale, tar sands, solar, fission, fusion, wind, tides, biomass, etc. Actually, the list is endless because new possibilities are continually being proposed. Of these possibilities, coal uniquely stands out as an attractive substitute for petroleum. Coal can be, and is, burned to generate electricity and provide heat. It can be liquefied to supplement the liquid fuels from petroleum, and it can be gasified for use as synthetic natural gas. Unlike exotic alternate energy such as solar and fusion, coal has successfully been used commercially to produce synthetic fuels. But, the technology does need to be refined and modernized. Thus, coal's role is not to be "America's Ace in the Hole," but to bridge the transition from primary dependence on petroleum for energy to the utopia of renewable sources of energy. But don't be mislead by the prophets--those renewable sources of energy are going to be very, very expensive when they are invented.

Jan 1, 1978

By Veliko Kertikov

Complicated processes of heat exchange and evaporation, leading to changes in the temperature and humidity of the ventilating air flow, take place during the driving of headings. In the case when virgin rock temperature is high, the increase in air temperature and humidity is significant. This causes a deterioration of climatic conditions in the headings. Procedures for predicting the changes in air temperature and humidity are discussed, together with appropriate calculations and computer programmes. Predicted results for example scenarios are used as a background for the selection of approaches and means to improve the climatic conditions in a dead-end heading using auxiliary ventilation.

Jan 1, 1997

By Osvaldo A. Bascur

The implementation of continuous quality improvement is the confluence of Total Quality Management, People Empowerment, Performance Indicators and Information Engineering. The supporting information technologies allow a mineral processor to narrow the gap between management business objectives and the process control level. One of the most important contributors is the user friendliness and flexibility of the personal computer in a client/server environment. This synergistic combination when used for real time performance monitoring translates into production cost savings, improved communications and enhanced decision support. Other savings come from reduced time to collect data and perform tedious calculations, act quickly with fresh new data, generate and validate data to be used by others. This paper presents an integrated view of plant management. The selection of the proper tools for continuous quality improvement are described. The process of selecting critical performance monitoring indices for improved plant performance are discussed. The importance of a well balanced technological improvement, personnel empowerment, total quality management and organizational assets are stressed.

Jan 1, 1995