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By D. G. F. Hedley, S. N. Muppalaneni, J. W. Roxburgh

A stope and pillar method is used to mine the gently-dipping uranium bearing reefs, to a depth of 1000 m, at Elliot Lake, Ontario. A few isolated rockbursts have been reported in the 11 mines in the area during the first twenty-five years of operation. However, in March 1982 a series of rockbursts were initiated in the old mined-out workings at the Quirke Mine of Rio Algom Ltd. Detailed records of pillar deterioration and size of the affected area were kept both prior and subsequent to the occurrence. Seismic instrumentation was installed before and convergence stations shortly after the start of bursting. Observations indicate that the squat pillars failed violently where- as the slender pillars exhibit a less violent failure mechanism. Floor cracks and heaving are common, but the massive quartzite hanging wall strata is relatively undamaged although some roof falls have occurred due to local structure. The microseismic system accurately locates seismic events to f 20 m within the geophone array and it has been found that an accelerating convergence rate coincides with and in some cases precedes an increase in seismic activity. Displacement discontinuity and boundary element computer models have been used to estimate pillar stresses and areas of high stress concentration in an effort to determine the causes of rockbursts. Mine and pillar stiffness and energy balance concepts are used to explain cases of gradual and sudden pillar failures at Quirke Mine.

Jan 1, 1984

By D Syme

In the middle of 2000, BHP Billiton implemented a Six Sigma Plus business improvement program known as Operating Excellence. It was developed based on a business bottom line initiative to deliver 35 - 40c/share and was one of the BHP Billiton strategies to deliver $2 earnings per share and a longer term $40 share price (BHP share price). Cannington is a silver, lead and zinc mine owned and operated by BHP Billiton. Through implementing Six Sigma Plus Cannington wanted to:have in-house capabilities to change and improve; tailor for the needs of each business unit and department; have æSharing of its KnowledgeÆ as a tool for improvement and have a competitive edge across Cannington û to be better than our competitors; learn from and leverage off the successes of improved safety and prior business improvement efforts; and ensure networking and sharing of information have common measurement systems across all assets. As with most business improvement programs û Six Sigma Plus was met with some degree of skepticism, especially given the amount of resources involved. After 18 months, much of this skepticism has been replaced with enthusiasm as peopleÆs understanding and acceptance of its fundamental concepts are being realised. The idea behind Six Sigma Plus is that it combines sound technical solutions with high acceptance by those who need to work with or implement the change. The future vision for Six Sigma Plus is that it become part of what we do at Cannington û just like safety and environment û so that Six Sigma tools and methodologies are used in our every day work.

Jan 1, 2002

By P. E. Cavanagh

THE Ontario Research Foundation has developed a family of dry magnetic concentrators which, when used in conjunction with a dry grinding mill such as an Aero-fall mill, will allow the production of a completely dry magnetite concentrate. Previous experience with extrusion of iron ore and with pelletizing of fine iron concentrates suggested that it might be possible to develop a method particularly suited to the agglomeration of completely dry concentrates which might have some practical advantages over other methods of agglomeration. Pelletizing is the preferred method of agglomerating very fine iron ore concentrates. Magnetite concentrate is fod to the pelletizing equipment in the form of a moist filter cake. Binders and plasticizers may be added if necessary, and the moisture content must be increased or adjusted to the percentage necessary to give good balling action and satisfactory green strength in the resulting moist pellets. The moist ore with a closely controlled water content of about 7 to 12 per cent moisture may be rolled into pellets by a snow-balling action in a pelletizing drum, a Lurgi pan, or a Mac-Dowell disc pelletizer. The resulting green pellets are fired by one of several alternative processes to produce a hard pellet which has sufficient strength to withstand handling and shipping.

Jan 1, 1957

By Erich Steinlechner, Freddy Lopez

The Rhine, with its length of approx­imately 1,230 km (764 mi), is the second-longest river in Central and Western Europe and one of the most important navigable waterways in the world. The alpine Rhine (or Alpenrhein) is the section of the river between Reichenau, Switzerland, and the Rhine's confluence with Lake Con­stance on the borders of Germany, Austria and Switzerland. A Swiss­Austrian flood control project known locally as RHESI aims to protect the habitat of about 300,000 people living in the valley along the "international stream" of the alpine Rhine. Along the international stream, the Rhine flows within a central channel toward Lake Constance in a canal-type bed with fortified embankments. In the event of rising water levels, the Rhine floods the foreland, stressing the existing flood embankments (dams). In order to allow even larger amounts of water to flow off safely, more space and new (or rehabilitated) dams are re- quired. With the implementation of the RHESI project, the middle channel of the Rhine will be significantly widened, and the foreland reduced, creating more space for the river. Around 65% of the flood embankments will be rehabili- tated and 25% completely renewed, while 10% of the dams will remain as they are today. These measures will increase the discharge capacity from the current 100-year to a 300-year flood rate. More discharge capacity means better protection against flood events.

Jul 1, 2024

By Eddie Martin

Jim Walter Resources, Mining Division, employs the retreat longwall mining system as the primary method of coal production. The strata control aspects of developing and maintaining roadways for retreat longwall mining have continued to improve and advance at Jim Walter Resources. New and innovative concepts in pillar design, roof and rib support, as well as longwall face support, have been combined to provide better strata control. Control of immediate roof breakup in the headgate and tailgate entries has been a problem at Jim Walter Resources' mines. The application of roof trusses as supplemental roof support failed to provide the desired strata stability. The immediate roof deterioration has been controlled through the installation of increased density of roof bolts in the affected roadways. Control of the rib sides has been a documented problem at Jim Walter Resources' No. 4 Mine since its start-up. The installation of 3/4 inch diameter roof bolts at 2 ft. spacing failed to control rib rolls. The development and application of a yieldable rib support system provided the desired results. Rib rolls have been virtually eliminated where the yieldable system of rib support has been installed. An evaluation of longwall panel development using the total yield pillar mining plan has been completed. Results of the strata stability and other operational data have been compiled. Coal production and gate entry stability were not adversely affected using the total yield pillar mining plan for longwall panel development. Strata Control on the longwall face is provided by the face support system. Excessive convergence and roof breakup along the longwall face have been experienced at several of the Jim Walter mines. In an effort to eliminate this problem, an evaluation of higher setting pressures for longwall face supports is being conducted. Results have been inconclusive to date. Each of the above strata control projects will be presented as case studies. Since Jim Walter Resources business is coal production, emphasis will be directed toward the application rather than the theoretical aspect of the projects.

Jan 1, 1988

By E. P. Chen

This investigation involves the development of a two-dimensional continuum model for the description of jointed media. Specific application of the model developed here is for the potential geological disposal of radioactive waste in the layered sequence of fractured volcanic tuffs under Yucca Mountain, Nevada. This is currently being considered by the Nevada Nuclear Waste Storage Investigations Project, administered by the Nevada Operations Office of the U. S. Department of Energy. The work is a direct extension of the previous constitutive model by Thomas (1982) based on the work of Morland (1974). The main feature of Thomas's model includes two parts: a continuum approximation based on average discontinuous displacements across jointing planes within a representative elementary volume, and a material constitutive description based on linear elastic matrix material behavior and nonlinear normal and shear joint behavior between jointing planes. The mathematical descriptions by Morland based on strain partitioning among matrix material and joint sets allow multiple joint sets to be included in the model. However, the initial effort by Thomas to implement Morland's mathematical model included only a single set of joints. To make the material model reflect more realistically the field characteristics, the current work extended Thomas's model to include orthogonal sets of joints. The nonlinear elastic normal joint behavior is retained in the present model. Joint shear response was treated as linear elastic in the shear stress versus shear displacement relationship prior to attaining the stress level governed by the Coulomb friction criterion. Beyond this critical stress value, a horizontal line is assumed in the work of Thomas for the shear stress versus slip displacement relationship such that the shear stress remains constant while the slip displacement increases. Motivated by experimental observation, the current work generalized the shear response to allow a line with finite slope to govern the slip behavior beyond the critical stress level. The inclusion of an orthogonal joint set led to a fourth order algebraic equation for the calculation of stress increments as compared with a second order equation obtained by Thomas. The nonlinear elastic normal joint behavior provides criteria which allow the selection of the root that yields result consistent with the loading condition of the problem. The addition of one more set of joints provides the potential to more completely study the interaction of various parameters representing the characteristics of jointed media behavior. Material responses to various loading conditions based on the present constitutive model have been obtained. These results and their comparisons to single joint set results are presented. Formulation of the Continuum Model The inclusion of an orthogonal joint set led to a fourth order algebraic equation for the calculation of stress increments as compared with a second order equation obtained by Thomas. The nonlinear elastic normal joint behavior provides criteria which allow the selection of the root that yields result consistent with the loading condition of the problem. The addition of one more set of joints provides the potential to more completely study the interaction of various parameters representing the characteristics of jointed media behavior. Material responses to various loading conditions based on the present constitutive model have been obtained. These results and their comparisons to single joint set results are presented. Let us focus our attention on the set with normal n first. Let the jump dilation displacement and jump slip dasplacement associated with the [ ]

Jan 1, 1986

By Charles H. Kline

Industrial minerals are the Cinderella of the mining I industry. Often considered as just dirt by traditional hard-rock miners and oil drillers, these products nonetheless comprise the second largest segment of the industry and the fastest-growing one. With annual sales of $5.7 billion, industrial minerals make up 22% of the dollar value of U.S. mineral consumption. By contrast, metals account for only 11%. Fuels, of course, are dominant, representing 67%. The dollar values of production and consumption for the three segments of the industry in 1968 are shown in Table I. The growth rate of industrial minerals is shown in Table II. From 1953-1968, the current-dollar value of all U.S. mineral production increased at the average annual rate of 3.8% while that of the gross national product increased at 5.9%. Industrial minerals are the only segment of the mining industry that approached the growth of the overall economy in this period, with production values increasing 5.1% a year and apparent-consumption values 5.6% These data, expressed in current dollars, include the effects of inflation. The growth in U.S. industrial minerals production is even more striking when expressed in indexes of physical production. As shown in Table III, production of all U.S. industries increased by 4.1% a year from 1953 to 1968. The growth in production of stone and earth minerals just matched this figure. By contrast, the average annual increase for oil and gas was 2.2%: for metals, 1.6% : and for coal, only 0.6 %.

Jan 1, 1970

By D. C. Bard

THESE notes are based on the megascopic study of a suite of 2,400 specimens of minerals and ores from the Butte mines, combined with field observations at intervals over a period of several years. The estimate of average vein composition is based on field acquaintance with the veins. It is probably correct in its broader proportions, and should be of use for comparison. Chemical and Mineral Composition of Butte Sulphide Vein. Matter. Per Cent. Oxygen 43.00-Quartz, rhodonite, rhodochrosite, barite, calcite, and hübnerite. Silicon 36.00-Quartz, rhodonite, and willemite (very rare). Sulphur 5.00-Sulphides of. iron, zinc, copper, lead,. and sulphates of barium and rarely calcium. Iron 5.00-Ferric sulphides (pyrite, bornite, chalcopyrite), also in sphalerite, tetrahedrite, and rarely hematite and siderite. Manganese, . . . . 2.00-Rhodonite, rhodochrosite, and hübnerite. Zinc, . . . . 1.00-Spha erite, very rare wurtzite and willemite, and tetrahedrite and tennantite.

Jan 8, 1913

By George B. Clark, John W. Brown, Hemendra N. Kalia, Ronald R. Rollins

A new theory for three dimensional collapse of conical liners shows why the two dimensional theory may offer a good approximation. Shaped charge design parameters and rock target properties were investigated to determine their effects on penetration and breakage. Penetration in dolomite is somewhat similar to that in steel, but copper does not have markedly better penetration capabilities than brass. Several metals, liner thicknesses, cone angles and standoff ranges for each were investigated. Effective standoff is greater for aluminum than more dense metals. Optimum geometry appears to approximate that for metal targets. Resistance to penetrations was greatest for a red granite and dense siliceous rocks, and least for dolomite and porous sandstone. Hardness and compressive strength appear to be two important conventional proper- ties. The first order law does not apply to the rocks tested. Dolomite may be drilled with shaped charges, the holes sprung and round blasted successfully.

Jan 1, 1971

By Baafi E. Y

In this paper, impact of expert systems development is examined from the coal mining point of view. Some introductory concepts about expert systems are explained with a view to identifying possible beneficial applications of expert systems in coal Mining.

Jan 1, 1988

By Homer Turner

COALS, other than anthracite, have been so thoroughly studied under the microscope during recent years, that we now know what kinds of plants and what parts of plants form the bulk of lower rank coals from peat to bituminous coal. The microscope has also shown the state of preservation of such vegetation as well as the nature and distribution of products of plant decay. These and further details have been ascertained mainly through the employment of two methods of attack, section cutting and maceration. Anthracite has failed to respond to these methods, so well adapted to the study of lower rank coals and, therefore, has been neglected by investigators to such an extent that there is much doubt as to its microscopical characteristics. The object of this paper is to lift anthracite from its realm of obscurity by demonstrating the wealth of microscopical detail that is revealed when reflected light is used on a properly polished and etched surface and, further, to show the relationship between anthracite and bituminous coal.

Jan 2, 1925

By Steve Konieczki

[ ] Great Basin Gold Ltd. (GBG) owns the Hollister Mine and operates it through the wholly owned subsidiary Rodeo Creek Gold, Inc. The property is located in northern Nevada on the Carlin Trend gold belt within the historic Ivanhoe Mining District. The mine is located on the western edge of the Northern Nevada Rift, a major north-northwest trending structural zone that has localized middle Miocene volcanic rocks and numerous epithermal gold deposits. The precious metal deposits are low-sulfidation epithermal systems characterized by banded quartz veins with electrum and silver selenides. The Hollister Mine will employ the selective underground mining method of cut and fill. This will be combined with split shooting (resuing mining method) to optimize recovery and reduce dilution. The focus of mining will be on extraction of ?ounces? from the narrow-veins rather than trying to maximize tons. The initial drifts will be excavated along the strike of the vein and then capped with a substantial concrete sill pillar. Back stoping with hand held drills will be used to selectively mine the vein. The stopes will be backfilled with waste rock material. With every lift, an 18 inch concrete cap will be poured onto the backfill waste rock to prevent gold values from being lost into the fill. Targeted ore production rate will be over 400 tons per day. With current ore reserves, project life is estimated to be around eight years; however, Hollister geologists view the site as one of the most prospective systems for bonanza vein deposits in Nevada. Approximately $14

Jan 1, 2008

By C. B. Dudley

In a work published in 1838, De Morgan, the author of the article on " Probabilities," in the Encyclopedia Metropolltimn, says: " The method of least squares is not yet introduced iutb the affairs of common life,.....that many thi~gs which are denlonstrable only by the higher branches of mathematics are looked upon as useless." And he mentions an instance in which "a method was suggested for estimating the relative importance of boroughs, by considering their population and ~wntributions to the revenue con)-

Jan 1, 1881

By Leo J. Laughlin

In recent years, heavy mining applications have put an increasing demand on conveyor pulleys. This has resulted in the increased usage of turbine pulleys. The designs of these pulleys are often based upon the failures seen in the conventional welded designs, overlooking the interaction of pulley-shaft system components as the profile of the disc is modified. This paper will focus on the development of balanced design philosophy using case studies of turbine pulleys in heavy mining applications, evaluated with FEA.

Jan 1, 2002

By B. G. Fordyce, W. B. Parker

A description is given of the methods used in management planning, pit-equipment selection and maintenance operator training, and formal organization of mining personnel.

Jan 1, 1979

By G. T. Lineberry, L. Adler

Reduced clearance a one of the most important characteristics of encumbered space in underground coal mining. Another key variable is the maximum velocity at which a piece of mobile mining equipment can operate in this limited space. Typical velocity-clearance curves for different mine transportation systems are developed and characterized. Applications of the relationships are examined, emphasizing their significance in designing and controlling mine materials handling system.

Jan 1, 1985

By J. G. Bensley, K. S. Detheridge

"Many plants use computers for process control and most have computerized Management Information Systems but few have been able to have these systems interact with one another. Developing this system interaction is not a one-step process but requires careful planning and implementation. This paper describes two projects that were implemented to provide the bridge between the process control and management information systems of Cominco Limited. Both projects include the replacement of essentially process control systems installed in the late 1960s. These original systems provided an enhanced level of control in the form of Direct Digital Control (via computer/manual analogue control stations) and a management reporting capability of process data. The experience gained from the use of these systems over a period of fifteen years formed a basis for the evaluation and planning for the new systems. The new systems were commissioned in 1985 and 1986 and operating and further developments leading to a totally integrated process information and control system are underway. INTRODUCTIONThe concept of hierarchical control involves a control structure consisting of a number of defined levels. Each level performs a defined function with information consolidated and combined as it moves up through the hierarchical structure. The commonly accepted structure of a hierarchical control system echoes the structure of the plant which is being controlled. Referring to Figure 1:Level 0 - Sensors and ActuatorsSensors and actuators, such as thermocouples and flow control valves, interface directly to the process and are generally connected directly to the controllers or multiplexers at Level I.Level 1 - Regulatory ControlThis level provides basic PID control (proportional/integral/ derivative) typically using microprocessor based controllers and programmable controllers for digital control of motors and machines. Systems at this levelare usually segregated by plant unit, e.g, crushing, flotation, drying. Control is concentrated on achieving optimum conditions for a particular feed rate."

Jan 1, 1989

By K. N. Han, H. Lee, M. C. Fuerstenau

An investigation of the recovery of finely-divided cassiterite and silica particles less than 1 µm (1200 mesh) in size has been carried out using packed and fluidized beds. The bed particles used included cassiterite and silica particles ranging from 44 to 210 µm (325 to 70 mesh). Effects of various system parameters on the recovery and selectivity of cassiterite fines were investigated. System parameters included pH of the slurry solution, superficial velocity, slurry concentration, and bed particle sizes. High recoveries of cassiterite fines were obtained at pH 4.0 and slow slurry flow rates. In a packed bed system, recovery of cassiterite fines was greater than 95%, while that of silica fines under the same conditions was about 35%. Although the total recovery per pass is not as good as the packed bed, the fluidized bed system exhibits good recovery in general and an excellent selectivity of cassiterite fines. There is an optimum superficial velocity, vo, for the rate of fine particle uptake and the apparent rate constant has the form of Kvo1/2- K'vo, where K and K' are system constants.

Jan 1, 1985

By Fuller P. G, Miller D. R

Hydraulic fill using surface sand deposits or cycloned tailings has been used in underground mining for at least fifty years. Current technology requires a permeable fill and high cement additions for strong fill. Shortages in quantities of acceptable fill with finely ground ore may require rockfill or aggregate to be introduced as a supplement and these usually incur additional distribution costs. Alternative approaches to the problem are now being developed whereby the pulp density of the fill is raised so that it is delivered either as a dense slurry or as a paste. These regimes of fill behaviour are defined together with the plant and pumping techniques required to prepare and deliver the materials. Test techniques to define the different regimes of behaviour are identified and the variation in material properties for fills with varying pulp densities are outlined. The results indicate that high pulp density fills are stronger and have less permeability restrictions than conventional fills and that aggregate can be carried with the pulp. Thus the disadvantage of finer materials can be turned into an economic advantage. Criteria are developed for defining the type of operation suited to this Technology.

Jan 1, 1986

By Roberto Javier Santiago

The main properties of Calcium Carbide seem to be the grain size and the CaC2 content. This paper tries to describe the Calcium Carbide used in the South-American steel plants and how and where it is added.

Jan 1, 2006