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By Sigmund J. Sulinski

The following is a progress report on a continuing study being made by the Sanitary District for purposes of developing reliable data for predicting costs and progress on future tunnel contracts. All data available to date on five separate tunnel contracts has been analyzed. All were machine-mined in soft ground, all used steel ribs and wood lagging and finished inside diameters varying from 5'6" to 6'6". Basic data regarding progress per shift, hours mined per shift, hours of downtime per shift, cause of downtime and type of soil mined were reported by the District's resident engineer at the job site. Figure 1, Weekly Mining Report is an example of the form used. Data regarding manpower and equipment used during tunnelling operations was also supplied by the resident engineer during the course of construction. Soil type being mined was verified by the resident engineer during construction, by visual observation, and compared with data listed on a previously prepared soil profile. The soil profile is a graphic presentation of anticipated soil stratas superimposed on a cross section

Jan 1, 1997

By Joaquin Marti, Peter A. Cundall

This paper reports on some recent work in which several schemes were developed to model jointed rock under high stress, with particular reference to the phenomenon of "block motion" observed during dynamic loading of underground structures. Three approaches were made, corresponding to an increasing relative importance of internal block deformations as compared to rigid block movements. The first one uses distinct element method and assumes internally rigid blocks, which can break, repeatedly, whenever an empirical crack criterion is met. In the second approach each block is allowed three degrees of freedom to deform internally. The third approach, still in the development stage, permits arbitrary deformation of all blocks, which are internally decomposed into finite-difference zones and automatically rezoned during slip to preserve the calculation accuracy on joints. The last two schemes allow arbitrary constitutive relations for the intact rock, and all three schemes permit the geometrical arrangement of joints to be arbitrarily complex, in contrast to normal Lagrange, finite-difference programs, which are unsuited to model discontinua.

Jan 1, 1979

By N. S. Dalal, Xianglin Shi

Metal ions, such as chromium (Cr) and vanadium (V) are found as trace impurities in mineral dust. Since metal ion mediated free radical generation has been implicated in many disease processes, we carried out a detailed investigation of the metabolism of these metal ions by biological redox systems and the possible oxygenated radical generation therefrom. We found that highly reactive Cr(5+) species are generated in the reduction of Cr(6+) by NADPH-dependent glutathione reductase, lipoyl dehydrogenase, and ferredoxin-NADP+ oxidoreductase. The reduced metal ion species react with hydrogen peroxide, to generate hydroxyl (•OH) radicals in a continuous cycle. The enzymatic catalysis processes also involves the reduction of molecular oxygen to the superoxide [(0-1 2)] radical. Thus only a trace amount of metal ions chemisorbed on mineral dusts, such as quartz, can catalyze the generation of the highly toxic oxygenated radical species from cellular hydrogen peroxide, suggesting a new biochemical mechanism for mineral dust induced chronic lung injury.

Jan 1, 1991

By Norman D. Harte, George W. Holl

The development of the most important tool used in Site Testing is reviewed briefly and the application of the information gained is described. The operation of Site Testing and pregrouting of underground excavations is dealt with in detail. Practical experiences (and pitfalls into which the inexperienced might fall) are recorded. But for the application of Site Testing and grouting of shafts, tunnels and other excavations, vast areas of the present goldfields in South Africa would remain unexploitable.

Jan 1, 1981

By David J. Dyet

Computer applications in the past five to seven years have become a typical and necessary practice in most modern geological offices. Manual calculations, interpretations and plotting of data can be, at times, quite tedious, inefficient and lacking in ac- curacy. The introduction of geostatistical and geological software can eliminate these problems. Computer applications in the uranium industry are not new; however, they are constantly being developed. A variety of soft- ware programs are available. Generally, these programs support most geological and geostatiscal applications in uranium mines. The Rabbit Lake Operation - Eagle Point mine in Northern Saskatchewan is a high grade mine, as one such case. Computer applications at the Eagle Point mine have been a mainstay in the geology department, since the mine's collaring in 1991. This paper presents a discussion on descriptions of programs, operations and applications of computers. It also explains and de- scribes the radiometric equipment used at Eagle Point. This pa- per will demonstrate how, by using computer systems, mine site information flows reliably with the involvement of computers.

Jan 1, 1996

By Hector M. Valenzuela, Juan H. Rojas

This paper presents a strategic plan for automation, plant integration and process management being implemented at the Chuquicamata mining and metallurgical complex of Codelco-Chile. This five-year plan considers different levels of process control and plant integration, which include instrumentation and direct control, process models and supervisory control, plant information integration, and real time process and plant wide management. The conceptual solution developed defines an architecture for the overall system and the projects to be implemented by each production unit, as part of the proposed solution for the division wide process control, plant integration and real time process management. An estimate of the cost benefit relation of the plan is also given.

Jan 1, 1998

By George A. Hoffman, Richard J. Proctor

INTRODUCTION We will discuss here only the subway construction phase; that is, two to five years at a given location--not the long-term analysis. We also will compare some tunnel construction methods used for BART and in Los Angeles. Typically, urban planners and engineers try to balance a new mass transit system to include tunneled subways, cut-and-cover construction in city streets, and elevated guideways. Their decisions are based on many factors, most of which can be quantified. But there are some socio-economic-environmental factors which are almost intangible, or nonquantifiable, and these are rarely included in the final report for a rapid transit system. There are two reasons for this: First, it is difficult to evaluate disruptions and psychological inconveniences to individuals and to the community during the construction period, and even more difficult to assign costs because the valuations are always subjective. Second, the rapid transit project capital costs are given in the final report and the public knows them; but the intangible social costs are borne by the affected neighborhood community, not the entire city, and as such they are "hidden costs," which in fact may add as much as 25 percent to the total system cost.

Jan 1, 1974

By Prasad Kummarapurugu, Maija Teijonsalo, Sirkka-Liisa Jamsa-Jounela

There has been a significant progress in the use of mathematical modeling and simulation in the minerals industry in the last decade. Process models have moved from academic world to important industrial tools. This paper reviews the status of mineral processing simulators and recent progress in simulator development and applications is discussed. The simulation for process design and optimisation is now an established technique, as evidenced by its increasing use of practising engineers through commercially available simulator software. The paper presents a systematic approach to the process study procedure for the control system development, clarified by practical case examples calculated by SimCon - a novel steady-state simulator for mineral processes. Examples of the application of SimCon in drawing flowsheets, calculating mass balances and making simulations for grinding and flotation processes are presented. At the end of the paper, the state-of-the-art and the future of computer-aided pro- cess study at mineral processing plants is discussed. Keywords: Simulators, modelling, object oriented programming, computer aided control system design

Jan 1, 1996

By A. G. Belova

Conversion of coal into high-value gases via gasification offers significant pollution reduction and efficiency improvement benefits associated with controlled combustion of clean gases for power generation. However, current gasification-based electricity production technologies, such as IGCC do not address carbon dioxide emissions. The focus of the study is CO2 capture on CaO prior to combustion of coal-derived gases. To overcome kinetic and stability limitations associated with its utilization, CaO is distributed on high-surface area -Al2O3 and supported on a ceramic honey-comb monolith. The proposed method allows for efficient capture of CO2 from a gas mixture, as studied in a flow-through reactor system. This novel method of CO2 capture is used here to argue for pre-combustion capture of CO2 in coal gasification-based power plants. When CaO is present during the steam reforming of coal gasification gases, continuous withdrawal of CO2 from the system provides for higher yields of reforming products (hydrogen gas) by influencing the thermodynamic equilibrium of the entire system.

Jan 1, 2009

By William R. Nash

The scope of work for the fast track construction of the Weeks Island Replacement Facility, Weeks Island, Louisiana included the design and construction of two salt mines. Mine #1 - An interim underground mining level consisting of a 975 m (3200 ft) incline and 3520 m of 5.5 m x 7.3 m (11560 ft of 18 ft x 24 ft) drill and blast excavation; raise boring; core drilling; roadheader excavation; complete bulk material handling facilities utilizing an existing production shaft. Mine #2 - Simultaneous with the interim mine construction a new one million ton per year underground salt mine was constructed consisting of: two 5.5 m diameter x 381 m (18 ft diameter x 1250 ft) deep shafts; 76450 cu m (100,000 cu yd) of drill and blast bottom excavation; surface and undergound bulk material handling systems (conveyors, skip loaders, shaft equipment, hoisting); ground freezing for water control for both the production and service shafts; the design of the first underground doublewall slipform installation of a dynamic bitumen shaft lining system; the emergency grouting of both the existing production shaft and the interim mining level in the salt dome; 227 mt x 64 m (250 ton x 210 ft) high structural steel production headframe; 2.2 MW (3000 hp) double drum mine hoist; service shaft headframe; and service buildings.

Jan 1, 1987

By Gary Schaffer, Anthony Stentz

Surveying of mines is a necessary step in coal mining to assemble maps which are used for tracking progress in the development of the mine and to plan future coal removal. A first approach for automatically building high-resolution two-dimensioml maps of underground coal mines is presented. The technique assembles laser rangefinder scans obtained from several locations within the mine into a consistent global map of the mine. Each range scan comprises thousands of data points collected in one second, thereby achieving higher resolution and much faster measurement compared to a human using a transit. The raw data (range scans) are processed to fuse them into a consistent representation. This paper describes a first approach to automated surveying and presents initial results of merging range scans. Improvements to the scan-merging algorithm are proposed.

Jan 1, 1993

By S. Saklar, i. Bayraktar

The effect of the feed size distribution on the kinetic parameters in pyrite flotation was studied. The kinetic parameters of the particular sizes were determined as a function of whether other particle sizes were present. From the data, a relation between the pyrite flotation rate and the particle size distributions was obtained. It was shown that the flotation rate constant (k) is a function of the size modulus (dt) of the Gates-Gaudin-Schuhmann distribution, and its variation may be expressed as k = a • exp(b . d,) for either individual size fractions or composite feed. Parameters a and b are dependent on the particle size distribution of the feed. Specifically, parameter a increases linearly as the distribution becomes coarser. The above relationship was also tested under conditions in which the collector (KAX) dosage was varied from 130 to 278 g/t. It was shown that the established relation was not dependent on the collector dosage.

Jan 1, 2002

By Abdullah Arik

In deposits with highly skewed grade distributions, such as precious metals deposits, proper handling of the outlier high grade data is very crucial to the ore reserve estimation. Although some recent geostatistical techniques are available to handle the estimation problems with these outlier data, ordinary kriging or conventional methods are still widely used to estimate the ore reserves for such deposits. One reason for this is the fact that the alternative methods offered are either too complex or too exhaustive for the mine engineers and geologist who often do not have the expertise or the time to apply these methods. This paper presents a new 2-step kriging algorithm "Outlier Restricted Kriging" (ORK) which can be a simple and a practical tool to use where the ordinary kriging will fail to handle the outlier high grade data properly in block grade estimation. The paper details the methodology and discusses the results of its application to a gold deposit.

Jan 1, 1992

By A. D. Davis, C. J. Webb, F. W. Beaver

The proposed National Underground Science Laboratory will be housed in the former Homestake Gold Mine at Lead, South Dakota. Uses will include underground neutrino experiments that must be shielded by several thousand feet of rock, as well as ground-water research in fracture-flow environments, and investigation of the microbiology of extreme environments. The Homestake Mine has about 300 miles of underground workings. Seepage of ground water into the mine openings is approximately 500 gallons per minute. Average annual precipitation in the northern Black Hills is approximately 28 inches per year. The majority of this becomes surface-water runoff or evapotranspiration, with little ground-water recharge because of the low permeability of the Precambrian rocks in the area. Dewatering of the workings over the 125 years of operation of the mine has influenced the subsurface hydrology of the 8,000-footdeep mine.

Jan 1, 2003

By D. J. McKee, D. M. Wiseman

The usefulness of simulation as a technique for metallurgical process design and optimization studies has been greatly extended over the last few years by the development of a number of general purpose simulation packages. The packages, or simulators, all have the common objective of presenting the mathematical models and simulation methods in a form which is readily usable by plant engineers and metallurgists. To date, most simulators have been concerned with steady state simulation, but packages capable of dynamic simulation are now becoming available. The paper outlines the essential features of versatile steady state and dynamic simulators. Typical applications are presented by considering examples of design and optimization studies. Limitation on the use of simulators are also presented.

Jan 1, 1991

By Jin Anshi, Wang Dai, Wang Zingshen

Both fire and gas problems in Fully Mechanized Sublevel Caving Coat Face are quite different from those in common fully mechanized coal face. Pouring N2into the goaf would be the best method to prevent fire in the goaf. In this paper how to determine parameters of pouring N2 is discussed. Comparing distributions of gases and temperature before pouring N2into the goaf with those after pouring N2 into the goaf, the effectivenesses of preventing the fire by pouring N2 into the goaf are testified. Some special gas problems appear in Fully Mechanized Sublevel Caving Coal Face, which are proved to be serious and interrelated with pouring N2 into goaf. Finally, a few methods adopted to deal with gas problems are described simply.

Jan 1, 1991

By Bruce Congleton

The Florida phosphate industry is a leader in environmental control, both in terms of dollars spent and significant achievements. For instance, since 1960 the phosphate industry has spent over $71 million for air pollution and control devices, including installation, research and development and maintenance. Water pollution control expenditures also total in the millions, with over $69 million spent in the same 10 year period. The industry also is a leader in water conservation measures, having spent nearly $ 18 million since 1966 for conservation devices. Since phosphate is mined by strip mining, land reclamation plays an important part in the environmental control picture. Here again, the phosphate industry has met the challenge with a voluntary program of reclamation which accounts for over 20,000 acres of land useable after mining has taken place. In terms of progress in environmental control, the industry has been able over the years to solve within the limits of technology the fluoride emission problems it once had, and is currently at work solving sulfur dioxide and particulate problems. In just the past year the industry also has been extremely successful in limiting phosphorus and nitrogen discharges into area streams. The industry continues to cooperate with state and local pollution control officials on matters of environmental control, and future plans include even closer cooperation and assistance, as well as increased expenditures.

Jan 1, 1972

By F. A. Kruse, R. J. Madrid, P. L. Hauff

Sub-microscopic gold grains in disseminated gold deposits in Nevada are often directly associated with the clay mineral illite. Delineation of gold ore-zones can be improved by accurate characterization of the associated illite varieties or polytypes. X-ray diffraction studies of clay minerals from several disseminated gold deposits demonstrate that illite polytypes reflect lateral and vertical zonation around the ore bodies. Polytypes act as geothermometers indicating temperatures of ore deposition and proximity to hypogene and supergene fluids. Visible/near infrared spectral measurements using a field-portable reflectance spectrometer provide a reconnaissance technique for mapping the in-situ distribution of illites. Changes in the visible/near-infrared reflectance spectra are observed as illites progress from the lower temperature, less ordered 1 M variety to the higher temperature 2M type. The combination of the reflectance spectroscopy with the X- ray diffraction data creates a powerful tool for detailed mineralogic mapping for gold exploration.

Jan 1, 1989

By Regina N. Tempel, Mae S. Gustin, Mark A. Engle

This study characterizes the hydrogeochemistry of groundwaters near opalite-hosted epithermal hot-spring type mercury deposits in the Ivanhoe mining district, Elko County, Nevada. Local groundwaters generally range from Ca-HCO3 to Ca-Mg-Na-SO4 type waters with background mercury concentrations ranging from 0.014 to 0.32 ug/l. Leaching experiments conducted on mineralized rocks, using typical water chemistries to represent local groundwaters, yield total mercury concentrations ranging from 6.3 ug/l to 27.4 ug/l after one year of reaction. Geochemical modeling indicates dissolved mercury is dominated by HgO(,) and that precipitation of quicksilver controls mercury concentrations to an upper limit of 63 ug/l.

Jan 1, 2000

By J. Kemeny, B. Norton, T. W. BoBo

Digital image analysis systems to quantify particle size of crushed materials have successfully been applied in large-scale mining operations throughout the world. Particle size measurement at various crushing and sieving stages, especially in aggregate production, will facilitate the industry’s desire and need to achieve higher levels of process control and automation. This paper will 1) summarize applications of digital image analysis in the industrial minerals industries and introduce the Split-Online technology; 2) detail an actual recent test application of digital image analysis that ultimately lead to the installation of an automatic, non-invasive particle size distribution monitoring system; 3) document how this information is being applied: and 4) summarize the new Split-Online Aggregates Module now available.

Jan 1, 2004