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By J. Mersch Ward

Homestake Mining Company has identified a significant native sulfur resource at its Cinnabar Canyon prospect in Mono County, California. Elemental sulfur occurs as replacements, fracture coatings and breccia fillings in a thick sequence of Miocene-Pliocene intermediate volcanic rocks. The deposit extends along a northwest trending regional fault and measures approximately 900' in width, at least 1800' in length, and has a thickness in excess of 200'. The deposit lies approximately 150' below the surface and is covered by a silicified cap of volcaniclastic strata. The deposit has been delineated by rotary and core drilling. Utilizing a grade cutoff of 5% elemental sulfur, the delineated deposit has a probablelpossible resource of 16.1 million tons of ore averaging 17.9% elemental sulfur containing 2.57 million long tons sulfur. Assay grades within the resource area range up to 40% sulfur over a 40-foot intercept.

Jan 1, 1992

By L. C. Atkinson, E. A. Azrag, T. M. Hanna

The results of using a simple analytical solution and a relatively complex numerical model to estimate ground water inflow to an open pit mine are compared. The analytical solution assumes lateral, radial flow to a fully penetrating pit in an idealized confined aquifer, whereas the numerical model simulates fully three-dimensional flow to a partially penetrating pit from a water table aquifer. The latter is a more realistic simulation of the problem, but the former method is significantly easier to use. Comparison of the results obtained with the two methods for some typical hydrogeologic conditions encountered in mining yields ratios between them in the range of 0.2 to 0.6. These values can be used as a coefficient in the Pit Flow analytical solution to produce reasonable estimates of in-flow even when there are significant differences from the idealized conditions implicit in its application.

Jan 1, 1995

By P. R. A. Andrews, R. K. Collings

The beneficiation of barite has been the subject of many investigations at CANMET, thus reflecting barite's importance as an industrial mineral. Fifty-one studies relating to various aspects of beneficiation were conducted between 1920 and 1986, and a review of some of the more important studies is presented. The information, including mineralogy, beneficiation methods and results, flotation parameters, and reagent concentration data, is presented in tabular form. By so arranging the principal data, the research worker and production metallurgist will be assisted in the evaluation of barite ores from a variety of origins.

Jan 1, 1990

Acid mine drainage is still a common problem in the northern Appalachian high sulfur coal region despite mining and reclamation practices applied to control it. Mining companies must treat water with alkali to raise pH and precipitate metals in order to discharge the water into receiving streams. Common chemicals used to treat drainage are limestone, hydrated lime, soda ash briquettes, caustic soda, and ammonia. Each chemical has advantages or disadvantages under specific conditions. A simple spreadsheet program was developed to evaluate costs of treating acid mine drainage across several specified water quality parameters and time horizons. Caustic soda and soda ash were shown to be cost effective for treating low flows and low acidity over short time periods. However, as quantity of water increased, quality decreased, and time horizon increased, the ammonia and hydrated lime systems were found to be much cheaper than caustic soda.

Jan 1, 1991

By Thomas H. Koenning, James R. Boulton

The coal mined by Cyprus at the Shoshone mine near Hanna, WY is highly susceptible to spontaneous combustion. Spontaneous heatings have occurred in the gob of several of the longwall panels and, in some cases, following roof falls. Prevention and detection methods have evolved over the years as more has been learned about the occurrences. Seal design and construction have progressed to reduce air leakage into the gob. Pressure balancing has been successful as a supplement to good workmanship in reducing leakage. Early heating detection has improved as knowledge has been gained. Prior methods of detection relied upon thermocouples detecting a temperature change. Later a gas chromatograph was used to analyze gob gas samples. Initially the products of combustion (POC) were relied upon for detection. Most recently, lack of oxygen depletion in the gob has been used as an early warning of problems. Examples are presented to illustrate the evolution of spontaneous combustion control at the Cyprus Shoshone coal mine. Methods have been developed which minimize the oxygen concentration in the gob and reduce the potential for spontaneous combustion.

Jan 1, 1997

By G. D. Trump, F. L. Stanley

Spirals have become one of the most popular methods for treating fine coal. Unfortunately, spirals tend to produce an undesirably high specific gravity cut point and often misplace significant amounts of coal and/or rock. In the present study, a process-engineering tool known as linear circuit analysis was used to identify problems with traditional spiral circuits and to suggest alternative configurations. These analyses indicate that a modified rougher-cleaner circuit incorporating a middlings recycle stream offers the best option for improving performance while maintaining a reasonable circulating load. In light of this finding, a full-scale test circuit was installed and evaluated at an existing preparation plant. Data obtained from the plant tests indicate that the new spiral circuit can simultaneously reduce the cut point and improve separation efficiency. Preliminary economic analysis show that the new circuit provides an attractive payback on capital investment.

Jan 1, 1999

By Malcolm J. McPherson

This paper describes the algorithm used in a BASIC program for an IBMXT microcomputer, to simulate the underground mine climate. The program called CLIMSIM has been developed and refined over several years as a result of considerable use at operating mines. The program has been designed to be easy to use and be understood by the practicing mine ventilation engineer. It provides predictions of the work place climate, so that the optimum ventilation/cooling system can be designed to obtain a certain air cooling power or effective temperature at the work place. An example is given of the application of the program to a mechanized cut and fill stope at the Homestake gold mine in South Dakota.

Jan 1, 1986

By X. Wen, D. Tao, B. Li

A high effective method using a hammer mill, a column pneumatic separator and an electrostatic separator was studied for recycling copper from waste printed circuit board. The factors influencing the copper liberation degree and following separations were discussed. Two different physical separating methods were compared and discussed. Experiment results show that a well-controlled impact action can produce a satisfactory degree of copper liberation at a relatively coarse particle size. Around 90% copper recovery from printed circuit board for coarse particle size can be achieved by using a combination of electrostatic separation and pneumatic separation.

Jan 1, 2003

By M. S. Klima, A. Simard, M. L. Turek

Laboratory testing was carried out to evaluate several devices for recovering clean coal from bituminous coal refuse material. The bulk of the testing focused on using a dense-medium cyclone to process -0.6-mm refuse material. A hindered-settling column and a spiral concentrator were also used to process nominal 1.2 x 0.15-mm material. Product yields and ash contents were obtained for all tests, while partition curves were generated for selected tests from which the characteristic performance parameters (relative density of separation and probable error) were determined. The results indicated that the dense-medium cyclone was capable of cleaning down to 0.037 mm, while the other devices were effective to 0.15 mm. Keywords: Coal recovery, Coal refuse, Dense-medium cyclone, Hindered settling, Spiral concentration

Jan 1, 2003

By Erich U. Petersen, J. B. Hiskey, William J. Tafuri, Donald M. Hausen, X. H. Jiang, Douglas N. Halbe, G. Ramadorai

The extraction of gold from chloride solutions with activated carbon is examined. It is shown that the uptake of gold by activated carbon from chloride solution follows a mechanism whereby gold is reduced to the metallic state. Metallic gold appears as deposits both on the carbon surface and in pore space within the carbon particle. The deposition rate is dependant on the carbon particle size and pH. At low initial gold concentrations, the initial rate is insensitive to gold concentration. Sodium hypochlorite exhibits an adverse effect on the reduction reaction. The overall loading and initial rate of reduction are both decreased in the presence of NaC10. The effect of iodide on the loading of gold was also examined in an attempt to overcome the superficial deposition of gold on carbon.

Jan 1, 1990

By Kenneth R. Miller

Surface mine equipment operators in the Campbell County region of Wyoming's Powder River Basin have found new ways of solving old problems. Technology, experience, competitive pressures and an increasing grasp of economies of scale have driven mine operators, equipment manufacturers and suppliers to specialization of applications. In economic terms, today's coal price of $4.95/t ($4.50/st) equates to $2.53/t ($2.30/st) in 1980 terms - an incomprehensible value at that time. This article describes some examples of change and adaptation made by Powder River Basin coal operators in overburden stripping equipment and techniques. It focuses on the evolution of the design and use draglines, shovels, trucks, scrapers and dozers.

Jan 1, 1998

By N. Oswald

As coal mines age and become more developed, ventilation modeling becomes more important for the planning and continued operation of the system. Numerous studies have been performed and presented that address the collection of data and measurement of airway friction factor and resistance per unit length values. However, a quantitative analysis of the resistance for stoppings in coal mines for different construction materials and methodologies has not been adequately addressed. In order to develop an accurate/realistic ventilation model both airway resistances and stopping resistance values need to be determined. Over the course of the past two decades Mine Ventilation Services, Inc (MVS) has measured the resistance of stoppings of various construction types in mines throughout the world. An analysis of this data is presented in this paper along with a discussion of measurement methodology.

Jan 1, 2009

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 D. E. Ranta, Leigh A. Readdy

Defining classes of ore using geostatistical methods that match historical classifications has presented problems in the past. A simplistic and practical approach to this problem is presented. An example of the approach is presented using a porphyry-type system as a case study. The technique described uses area of drill-hole influence and known conditions from similar deposits, or the production history of the deposit being studied. It provides a practical bridging mechanism for defining the class of ore on a block-by-block basis using the error of estimation value developed during kriging. The approach provides a filtering method that refocuses attention on the adequacy of drill-hole spacing.

Jan 1, 1992

By D. E. Ranta, Neil D. O’Donnell, Thad B. Ostrowski

Ore reserve estimation at the Syncrude Canada Ltd. open-pit oil sands mine in Northern Alberta has evolved since the project's inception. Early techniques followed a conventional petroleum reservoir analysis format, with relatively widely spaced drill holes and semiquantitative grade data. Experience has developed a more standard mining approach, including classification of geological materials by both lithology and sedimentary origin, timely and multi-purpose drill holes, precise analytical data, empirical recovery factors, a computerized geological data base, and an orebody block model. Future efforts will involve enhancement of existing techniques, use of geostatistical algorithms, quantification of confidence limits, and improved control of the ore model by geological parameters.

Jan 1, 1992

By Serguei A. Diatchkov

The principles of classification of reserves and resources in the Soviet Union were developed in 1960. Mineral reserve calculations were reviewed by the State Committee on Reserves for approval, then registered in the State List of Mineral Deposits and included in the State Balance of the Reserves. In 1981, however, a new "System of Classification of Reserves and Resources of Mineral Deposits" was adopted. This classification system (Table 1) is still used today in the Commonwealth of Independent States (CIS). It subdivides mineral concentrations into seven categories in three major groups, based on the level of exploration performed: explored reserves (A, B, C,), evaluated reserves (C) and prognostic resources (P1, P2, P3). Explored reserves Explored reserves are calculated within exploration contours. Category A The A category is the highest level of classification for any given mineral deposit and requires comprehensive exploration. First, the ore body's position, shape and structure must be accurately delineated (Fig. 1). Next, the mineralogy of the ore body must be studied to determine its composition and properties as well as the distribution of both ore and detrimental components. It is also necessary to outline the blocks of barren rocks and limits of subeconomic ores and to distinguish between the different types, grades and physical-chemical properties (mineral texture and structure) of the ore, the

Jan 1, 1994

By James W. Evans

It appears that all extractive processes involve, at one or more points, fluids (gases or liquids) and that the flow of the fluid is an essential part of the functioning of the process. Usually that flow is turbulent and the turbulent flow frequently determines the rates of mass and heat transfer as well as other important phenomena such as bubble/droplet breakup and coalescence, particle suspension, etc. Over the past decade many attempts have been made to model turbulent flows in metallurgical unit operations. The present paper summarizes some of that work. Amongst the operations considered are agitated leaching, ladle metallurgy, electrowinning/refin- ing, induction furnaces, Hall cells and electro- magnetic casting. Where possible, comparisons are made between model predictions and experimental results.

Jan 1, 1990

By Wei Wu

A computer-aided method for optimization of bench blast design in surface mines is presented. The design procedures basically consist of two steps. Firstly, a series of normalized, full- scale bench crater tests must be carried out in the field to find the optimum burden that produces the largest amount of acceptable fragments and other parameters that defines the effective fracture zone. Next, the locations and initiation sequence of blast-holes will be determined in such a way that each hole, at its time of firing, will be responsible for same amount of burden rock and will be in a position favorable to effective fracture of burden rock. A computer software "B.B." which can assist the second step of the design is fully introduced and its application is illustrated by an example.

Jan 1, 1992

By G. Raspa

This article describes a procedure for calculating the recoverable reserves of stratified orebodies characterised by a thin and irregular layers. An application on the phosphate deposits in the N'Zeto region of the Popular Republic of Angola is also described. The procedure consists in building a block model of the deposit through the conditioned multivarial geostatistical simulation of small areal units. The recoverable reserves are then calculated and defined by applying to the model a selection processes based on measured geological/economic parameters taken from the drillholes: thickness of overburden and mineralised layers, economic grain-size fraction, grade. The procedure also takes account both of the geometrical constraints of the mining method and dilution. For reasons of confidentiality, a multiplier has been applied to the values adopted for the sampling data.

Jan 1, 1992

By Julie Mitchell

The U.S. Bureau of Mines is conducting research on the application of expert sys tens technology to mining equipment diagnostics and predictive maintenance, to increase mining productivity and efficiency. One of the greatest hindrances to mining productivity is the breakdown of equipment, causing lengthy and costly delays. A diagnostic maintenance expert system (DIMES) is being developed for the hydraulic system of a continuous coal mining machine. Through the use of such a system, the frequency of equipment failures and repair time should be significantly reduced. This paper describes the application domain, the functional requirements, and the problem approach for DIMES, the design and implement at i on of the knowledge- based system, the sensor work involved with the project, and the future plans for the continued development of this and other expert systems.

Jan 1, 1989