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By N. P. Reddy, Y. J. Wang

Stall or aerodynamic stall of axial flow fans has long been recognized as an important operational problem in mine ventilation. To develop a technique for characterizing fan stall in multiple fan ventilation networks, a research project was initiated through the Generic Mineral Technology Center for Mine Systems Design and Ground Control. Considering that fan stall is related to multiple operating points, this paper discusses a numerical model for multiple fan ventilation networks, and numerical methods for solving multiple networks solutions. It is hoped that the results of this project will lead to an innovative method of ventilation network analysis and simulation, thus preventing stall.

Jan 1, 1993

By Laura J. Carroll, Gordon A. Goldsmith

Experts, like many of the speakers at the SME Annual Conference, are frequently called upon by lawyers to assist them in litigation. Due to the technical nature of many cases, the testimony of an expert with knowledge and experience in a particular field is necessary to help a judge or jury understand and decide certain issues. Environmental litigation is no exception. Experts routinely are called upon to offer testimony to establish the existence of contamination and its source, as well as the potential health and environmental risks associated with the contaminants. This article will briefly discuss the factors courts apply to determine whether to admit expert testimony after the recent Supreme Court decision in Daubert v. Memell Dow Pharm., Inc., 509 U.S. 579 (1993). The Court's decision in Daubert overruled a long-standing test that had based the admissibility of scientific evidence on its "general acceptance" in the field in issue. Next, the article will discuss in general terms what a party must do to "link a particular defendant's conduct to the contamination involved in order to recover from that defendant. This link, known as causation, varies depending upon the type of claim being asserted. Expert witnesses are used extensively to help establish causation. JUNK SCIENCE OR GOOD SCIENCE- HOW DOES A COURT DETERMINE WHAT TO LET IN A frequent complaint in litigation involving technical or scientific issues is that one party or another is trying to use so-called "junk science" to prove its case. While some expert testimony might be so clearly lacking in support or so "off the wall" that a court can easily determine to exclude it, other testimony, especially testimony on the "cutting edge," is much more problematic. In 1923, the District of Columbia Circuit Court of Appeals decided the case of Frye v. United States, 293 E 1013 (1923). In deciding whether to admit certain expert testimony, the court in Frye stated that while a court will "go a long way in admitting expert testimony deduced from a well-recognized scientific

Jan 1, 1998

By Gerald V. Jergensen, Edward J. Samuel

Slurry system are the principal method for storage and transportation of solids within and between concentration operations In a mineral processing plant. A slurry 1s a mixture of solid particles In water, or a chemical solution, that behaves like a liquid. The design of slurry transportation systems is generally analagous to pumping and piping water, but with a few notable exceptions: • The interaction of particle on particle affects slurry transport. • Particles often interact with the fluid, particularly when chemicals have been added to the system. • Particles have a frustrating tendency to settle from the slurry suspension, especially into locations not considered In the design. • Solids have an affinity for wetted surf aces and tend to wear them away. Slurry transportation systems Include a number of separate components, each requiring special design considerations. A systematic evaluation of each component of a slurry transfer system will help overlooking the small details that could cause operational headaches. Most slurry transport systems include: • A receiving sump or tank that provides for mixing and/or momentary storage of slurry. • A driving force.. by a pump, atmospheric pressure or gravity. • A suitable conduit for transportation.. pipes or launders. • A delivery objective.. another sump or process vessel, or distribution system to several process points. • A control strategy and design to regulate the transfer operation. The design of the slurry transportation system normally evolves through the following steps: • Finalizing the process flowsheet and establishing the weights and volumes to be handled. • Identifying and characterizing the various process fluids and slurries. • Defining critical and minimum transport velocities of fluids. • Selecting a pipe diameter (or dimensions and gradient) and

Jan 1, 1986

By E. M. Van Eeckhout

The National Uranium Resource Evaluation Program (NURE) has produced a mass of geochemical data in the form of data files on tapes. This paper presents a methodology for utilizing those tapes in a simple, practical manner. An example is given of an analysis of the Butte quadrangle, Montana, tape obtained from the Los Alamos National Laboratory (LANL). The example details the sequence of splitting the data file, plotting histograms, cumulative frequency curves, concentration plots, and methods for evaluation. All programs are written in FORTRAN. The case study was performed using a mini- computer (DEC PDP 11/70) and standard plotting subroutines.

Jan 1, 1982

By J. M. Mutmansky, Y. J. Wang

The method usually used to predict the direction of flow in a connecting airway is to conduct a survey of the two existing nodes to be connected by the new pressure airway. It is then assumed that the air will flow from the node with the measured higher pressure to the node with measured lower pressure. This paper examines this direction-of-flow problem using properties of the system characteristic curve for a two-terminal network and specifies some conditions that will ensure that the air will flow in the direction anticipated. It was concluded that the only requirement is that all characteristic curves of the fans in the network should be strictly decreasing. Five numerical examples illustrate some important proper- ties of the direction-of-flow problem.

Jan 1, 2000

By R. F. Al-Fariss

The phosphoric acid industry is expected to develop in Saudi Arabia in the near future. There are three main reasons for expecting this: the discovery of phosphate deposits in the Sirhan-Turayf region, the construction of phosphate fertilizer facilities of the TSP, DAP and NPK plants on the east coast of the country, and the availability of an ample amount of sulfur As a by-product from the petrochemical industries. This study is a part of the research work performed in the chemical engineering department At King Saud University to evaluate the Saudi phosphate rocks for the wet process phosphoric Acid production and to test different flotation methods for the carbonate rich phosphate rock In a laboratory scale flotation cell. Experimental results for the above tests, as well as Beneficiation by calcination, are presented.

Jan 1, 1993

By J. G. Groppo, J. G. Justice, B. K. Parekh

Removal of particulates and/or metal ions from mineral/coal processing waste water is a necessity from the environmental point of view. This paper describes application of a novel AC- electrocoagulation technique to remove the particulates as well as metal ions using AC power. A series of laboratory tests conducted on a stable black water sample obtained from a sub-bitminous coal operation provided a clear supernatant (-10 NTU) from the suspension. The process also shows promise in removal of up to 90 percent of phosphate ions and other metal ions (copper and nickel) from solution. A preliminary economic evaluation of the process will also be included.

Jan 1, 1992

By Peter H. Grimley

It is important to realize that lending institutions have a very different risk-profile from that of an equity investor. For bank financing, a feasibility study must address the concerns of the lender and these can be summarized under the four 'PI Is: Project, Performance, Product and People. Generally, feasibility studies focus on the measurable project risks associated with a new venture, but frequently insufficient emphasis is placed on key risk areas such as ore grade and metallurgical recovery. Before accepting full or even partial non-recourse risk, financial institutions will demand evidence that the project was constructed according to specifications and within budget and that its Performance within agreed limits has been demonstrated. Product risk should be discussed in detail in any feasibility study. For industrial minerals, penetration of the market can be critical to success and for commodities with volatile prices, the sensitivity of the cash flow to a range of prices should be carried out. Methods of reducing price risk such as long term contracts or, in the case of gold, forward selling should be carefully evaluated. The People risk is rarely discussed in feasibility studies, but can be a key element. Few projects turn out to be faithful copies of the study and the ability of the operator to identify

Jan 1, 1988

By R. H. Seraphim

The name is derived from an Egyptian myth, "A beautiful lone bird which lived in the Arabian desert for 500 or 600 years and then consumed itself in fire, rising renewed from the ashes to start another long life." HISTORY This account of the first history is gleaned from old reports and documents which are listed in the Bibliography and from discussions with old-timers of the district. Prospectors were active in the vicinity of Greenwood in 189 1, and in that year staked the Mother Lode, Crown Silver, and Sunset. Henry White staked the Knob Hill claim in Phoenix on Jul. 15, 1891, and by the end of the year, other prospectors had staked most of the claims covering the valuable ore bodies in the camp. Much surface work done in the early years indicated that the values in copper, gold, and silver were low. Large capital investments were required to develop the ore bodies and build smelters. The discovery that the ore was practically self-fluxing greatly enhanced the value of the deposits. A map of the area showing the geology is given in Fig. 1. The bedded Brooklyn conglomerate is shown in Fig. 2.

Jan 1, 1991

By J. S. Stachulak

Inco Limited operates nine underground mines on the rim of the Sudbury Basin. These operations are situated near the City of Sudbury, 589 km (365 miles) west of Montreal, and 363 km (225 miles) north of Toronto. The ores are mined primarily for nickel and copper, and the principal minerals are pentlandite, chalcopyrite, and pyrrhotite. Total ore production from underground is in excess of 51,000 tons per day. The total volume of fresh air supplied to the nine mines is six million cubic feet per minute. There are 50 main fans in operation at these mines, powered by electric motors totalling 11,200 kw (15,000 hp). The trend in metal mining during recent years towards mechanization and high-tonnage production methods has greatly increased ventilation requirements. The flow of air must quickly dilute and carry away diesel exhaust fumes, dust created by mining operations, and the fumes of the explosives used in blasting. Mechanical ventilation is required to obtain the necessary volume and control, as natural ventilation pressures alone are, for the most part, inadequate and unreliable. In the event of a mine fire or other needs, close control of ventilation is essential. There are two unique heating systems presently in operation at Inco: Creighton Natural Heat Ex- changer and Stobie Ice Stopes.

Jan 1, 1989

By Murali M. Gadde, Syd S. Peng, C. T. Holland

Cutter roof failure is one of the most common ground control problems affecting the safety and economy of an underground coal mine operation. Several attempts were made in the past to understand the processes responsible for cutter development and to devise mitigating measures. Yet, many cutter failures still happen and their advance prediction remains as elusive as before. One of the reasons for the impasse in predicting cutters lies in the limitations of the current numerical modeling technologies. The development and propagation of cutters is a progressive phenomenon and continuum models can only approximate this process. Since the discontinuum modeling is severely restricted by the lack of reliable input data, alternatives must be sought to better understand cutter failures using the continuum models. This paper proposes one approach using strain-softening material model to simulate the cutter initiation and propagation process. An attempt has also been made to provide some insights into the reasons for the change in cutter location at different parts of a development layout.

Jan 1, 2005

By Ronald J. Doll, John Elkin, M. P. Evans

The application of "Alignment Free” right angle shaft mounted drive systems offers improved reliability and reduced costs for surface and underground belt convey- ors. Comparisons to conventional approaches will cover installation, operating, maintenance, and spares inventory cost savings. Various options for belt acceleration and load control on fixed and variable length (booster) belt conveyors will be reviewed for operating performance, reliability, and total cost. Lastly, a case study of a successfully operating installation will be highlighted.

Jan 1, 1996

By S. Majumder

The longwall face supports are provided to prevent the caving of the immediate roof at the working face. The thickmess of the immediate roof may be obtained from the working height and the average bulking factor. A strong bed, capable of withstanding maximum bending moment among the beds within the above roof, can be identified. The load on the strong bed may be obtained by finding out the overlying beds that will rest on the former during sagging. The limiting span, L, for this unsupported loaded bed, as a beam with built-in ends, can be calculated. The support density required at the supported span (face to goaf edge), a, during the first fall, is now estimated with a view to have a safety factor 2 at the face end, when bending failure occurs at the barrier end. However, the above value is inadequate to provide necessary safety margin against bending failure at the face end, during the subsequent cavings as cantilever, for L/a less than 20.6. d For the latter case a separate expression is derived.

Jan 1, 1986

By B. Ni, J. D. Robertson

A new radioactive tracer method for the measurement of airflow in inaccessible airways was developed. The method can be used in situations where studies of the mine-ventilation system are not possible using conventional flowmeters (anemometers). The method was tested in the ventilation laboratory at the University of Kentucky and in the US Bureau of Mines Experimental Underground Coal Mine and was utilized in leakage, dilution and flow-velocity measurements.

Jan 1, 1998

By Zsolt Csillag, Dragorad Ivankovic, Miomir Ceh, Anna Csordás-Tóth

Results of the common research work of ALUTERV-FKI and RI in field of ore dressing are presented here. Although monohydrate types of bauxites consist of finely dispersed minerals, however, in some cases certain contaminants (carbonates mainly), can be reduced by physical methods before Bayer process. Electronmicroscopy combined with computerized data processing is proven to determine the possibility of beneficiation and to control the different stages of ore dressing. Test results gained by Hungarian and Yougoslavian bauxite samples, contaminated by calcite, dolomite, siderite and pyrite, are discussed. Basic operations were: grinding (mostly dry) and classification, magnetic separation (mostly wet) and selective agglomeration. Only simple processes, having high efficiency and mostly dry ore dressing technique may meet the requirement of economical criteria. 1. [CONDITIONS OF ADAPTING THE BAUXITE DRESSING METHOD] Bauxite is a relatively cheap raw material, occurring in great bulks. Bauxite deposits may often lay far from the traditional ore processing plants, and in such cases the ore reaches the plants after long transportation. Some of these plants must face the difficulty that the resources of high quality ore are exhausted, they fall short of supply and, consequently, they must decide on whether to utilize the existing resources of poorer

Jan 1, 1984

By J. E. Gebhardt, P. E. Richardson

External control of the electrochemical potential of a bed of mineral particles was investigated by the US Bureau of Mines as a method for controlling particle interaction with organic collectors and, thus, flotation response. A cylindrically shaped, 200- to 300-g bed of sulfide mineral particles was used as the working electrode in an electrochemical-flotation cell. In a pH 9.2 sodium tetraborate buffer, chalcocite floated with ethylxanthate at applied potentials [=] - 0.25 V (versus the standard hydrogen electrode) ; pyrite floated at potentials [=] 0.15 V. Differential separation of a chalcocite-pyrite mineral mixture was obtained by controlling the potential, but the flotation response of the mixture did not follow the behavior predicted from measurements on the individual mineral beds. Chalcocite dissolution products had a deleterious effect on chalcocite-pyrite separation by activating pyrite so that it floated below the potential (~ 0.13 V) at which xanthate is oxidized to dixanthogen. A pyrite bed activated with a copper(II) sulfate solution exhibited a flotation response with a potential dependence between that of chalcocite and pyrite. Pyrite dissolution products had no effect on chalcocite flotation.

Jan 1, 1988

By W. L. Han, Y. D. Zhang, X. C. Li

Meta-systhetic technique for large systems engineering has been placed on the agenda. The meta-systhetic A1 approach should involve the integration of digital and knowledge info, from qualitative to quantitative analysis, etc. Some algorithms of meta-systhetic technique such as ANN-ES and GA-ANN are introduced. A case study follows - mining conditions evaluation by meta-synthetic A1 methods, including: setting up the structure of evaluation indexes system, deciding their grade of membership by ANN-ES algorithm; determining the weight values of evaluation factors by GA-ANN algorithm; and developing the integrated evaluation model.

Jan 1, 2002

By E. F. ‘Pat’ Nelson, Richard Broom

Our portion of this afternoon’s session is dedicated to the operation of automatic process control associated with small to medium size primary or SAG milling circuits. In recognition of the subject matter of this symposium, specifically precious metals, our historical reference is Rosario Dominicanna in the Dominican Republic, one of the largest gold producers in the Western Hemisphere. Plus a backward glance to review very briefly the initial performance of the big primary mills at Island Copper in British Columbia and Pima IV in Arizona. We will then get to the subject at hand with a discussion of a retrofit control logic recently installed on a 5000 hp primary mill. The focus of this review is the simple, inexpensive, and cost effective character of this retrofit installation.

Jan 1, 1984

By L. John Minnick

Current developments in using lime and limestone slurries to remove sulfur oxide gases from the stacks of coal- and oil-burning furnaces have established an important need for treatment systems which include adequate disposal of resulting waste materials. The paper briefly outlines the classes of scrubbers which are using lime and limestone and describes the characteristics of the by-product material being produced. Some discussion is also included relating to methods of disposal of the scrubber underflow. Since coal-burning plants also produce fly ash as a waste material, one system developed by the author's company combines this material with the sulfur oxide by-products. The mixture is processed in a manner which converts the waste products into usable materials with acceptable structural and environmental properties. Recent interest in protection of ground waters from heavy-metal leachates has made the fly ash-sulfur oxide system an acceptable means of disposal, because the conversion products have very low permeability and adequately encapsulate soluble salts within the hardened mass. Although only limited information is available on the types and chemical requirements of limestone used in these processes, a few guidelines are presented to indicate the range of materials that can be used with good results.

Jan 1, 1974

By J. P. Allen, D. A. Rice, H. L. Abercrombie

Cobalt, nickel and manganese can be recovered quickly, cleanly and selectively from cobalt-rich manganese ocean crust by leaching in dilute acid solutions in the presence of hydrogen peroxide. Common selective precipitation methods can then be used to recover these metals from the leach liquor. The leaching reaction produces only oxygen as a byproduct, and the waste residue from leaching was tested and found to be nonhazardous under existing EPA specifications. The leaching process is effective in either fresh water or seawater. This research is a part of the Bureau of Mines program to identify the mineral resources of the Exclusive Economic Zone and devise methods, for recovering their valuable components.

Jan 1, 1992