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By C. Timothy Shaw

Traditionally, only the large mining companies have maintained specialist departments in such areas as Rock Mechanics, Ventilation and Safety. To the small companies this has been a luxury that they could ill afford. Any work required by such companies in these areas, more complex than could be handled by the existing staff, was done by consultants. This situation is changing though and there is a need arising for many specialist departments. These changes are partly being brought about by the effects of inflation as the ever increasing costs are causing more and more operators to increase the size of their operations in search of economies of scale. In addition though the plethora of new laws and regulations are creating a need for many more specialists in all areas of mining in order to ensure compliance. The abovementioned factors, added to the existing Pattern of mines endeavoring to improve the working environment for their labor force, both for reasons of practical labor relations and also due to further legislative pressures, have thus created a climate where, in the near future, departments such as Rock Mechanics, Safety, Ventilation, Environmental Engineering and Subsidence Control will be commonplace in mining companies. It will no longer be practical to function without such services. Many mining companies already maintain such departments and this has particularly been true of the big mining groups of South Africa. From the experience gained by many of these large companies with specialist departments, it is clear that the maintenance of a cadre of experienced, competent professionals in such a department has not always been easy. It would seem from the experience gained that one can generalise and state that graduate mining engineers tend not to view specilisation as an optimum direction for their career development. It is of course true that many professionals, especially those with higher than a bachelors degree, do view these areas as valid career options, but even here experience shows that wastage is high. The time therefore seems to be ripe to take a look at this area in some detail to see whether reasons for the problems can be isolated. Working from that some suggestions can be made as to directions in which improvements might be made. If the challenge of the demands of the new regulations are to be met then such improvements must be made.

Jan 1, 1980

By R. C. Emmett

Gravity sedimentation is one of the most widely used unit operations in mineral processing and hydrometallurgy. Properly selected and operated sedimentation equipment can provide probably the most economical means of concentrating solids or clarifying solutions. Because of the variety of different approaches possible, including the use of modern flocculants, it is easy to overlook the optimum approach in selecting equipment. The different types of sedimentation systems that can be used in the minerals field and the sizing methods that are currently employed will be discussed here. Sedimentation applications usually fall into two areas, clarification or thickening. While the two operations are basically similar, the difference in emphasis (a well-clarified overflow as opposed to a highly concentrated underflow) results in significant differences in testing, equipment design, and operation. Clarifiers may be merely simple settling vessels with no special features, other than ample volume to provide the detention time needed for suspended solids to settle out of the feed slurry. Or, they can be designed to employ elaborate solids-contact techniques utilizing coagulants or flocculants to achieve more rapid clarification through the growth of particle agglomerates. Thickeners also are available in a wide variety of designs, with the main differences concentrated in the design of the raking mechanism. Thickeners operating in series (continuous countercurrent decantation or CCD) are used to recover valuable solution or purify the insoluble solids. Tray thickeners are used for recovering fine particulate solids such as alumina seed, but in other applications have been supplanted largely by unit thickeners or inclined plate units. Thickeners and clarifiers sometimes are used for storage of either solids or overflow liquor, or employed as precipitating reactors, such as in desilication applications. The use of flocculants and coagulants is much more common in modern processing plants, primarily due to the reduction in capital costs rendered possible through the use of these reagents. The terms flocculant and coagulant are often used interchangeably; generally, it is understood that flocculants refer to organic, high molecular weight synthetic or natural polymers which are useful in flocculating most suspended solids, but generally are ineffective on colloidal suspensions. Coagulants refer to chemicals such as those commonly used in water treatment, alum, ferric salts, lime, etc., which are usually far more effective on colloidal solids but cannot achieve the degree of agglomeration that is possible with the polymers. In some cases, both coagulants and flocculants are used in order to achieve optimum results.

Jan 1, 1986

By Silvia Misk, Cristina Araújo, João Felipe Costa, Roberto Rolo

Linear estimation methods are widely used for resource evaluation. Among the existing linear estimation methods, ordinary Kriging (OK) was accepted as the best estimator to determine the average ore grade of each block. However, OK is inadequate for modeling small blocks in relation to data spacing, resulting in over-smoothed models. In this study, the results of the recoverable resource from the short-term model are compared to estimated models generated by the traditional method, i.e., OK, and non-linear methods. The conclusion is that non-linear methods improve the accuracy and precision of the long-term model when compared to the model generated by OK.

Jun 25, 2023

By D. A. Fenton

The reliability of large diameter, high horsepower ball mill is paramount when large production and minimum downtime is required. The 17 ft. x 56 ft. double compartment ball mill at St. Lawrence Cement Company has the first gearless drive built in North America and has the world's largest hydrodynamic bearings currently built and running. The machine has seen three years operation and has met its specifications. The mill was designed by Aerofall Mills Limited and the gearless drive built and designed by the Canadian General Electric Company. This paper discusses the operation of the first North American installation of a gearless drive ball mill from the mechanical, electrical and process aspects.

Jan 1, 1977

By Ralph W. Barbaro

This paper presents a cyclic queueing model which evaluates the productivity of a shovel-truck materials haulage system. For a cyclic queueing problem with exponentially distributed service times, a cyclic queueing model provides exact solutions in a fraction of the time that simulation takes to produce an approximate solution. The model is applied to an example problem, and the results are validated with simulation. Simulation is used to show that the assumptions of exponentially distributed service times and steady-state are not serious problems. A cyclic queueing model can be used to quickly obtain an accurate assessment of the productivity of a shovel-truck system.

Jan 1, 1986

By J. Driscoll

After 30 years of success, Newmont Gold Company has temporarily ceased production from the original Carlin Pit. In late 1993, the Carlin East Decline was driven and an extensive underground exploration program was started. Today, Newmont Gold produces refractory ore from the Carlin East underground at the rate of 700 t/d (770 stpd) for an annual production of over 100,000 ounces. Over 70 underground miners enjoy the estimated 6-year mine life at Carlin East. About 70% of the ore at Carlin East is mined by mechanized longhole stoping with delayed cemented backfill. The remaining ore is mined by underhand drift and cemented fill methods.

Jan 1, 1997

By Albert H. Fay

The gypsum industry makes significant contribution to the wealth of our nation. This non-metallic mineral ranks in the highest order with America's most precious resources. Evidence of this is borne out by the fact that gypsum is a vitally necessary element in the building, industrial and agricultural industries. In 1967, the United States consumed 14 million tons of this valuable ore. Of .this amount 69% was required by the building industry for the manufacture of building materials. An additional 21% was directed to the industrial market, for the manufacture of Portland Cement and for other industrial uses. The remaining 10% was used for agricultural purposes.

Jan 1, 1969

By D. O. Murchu

Outokumpu Tara Mines located near Dublin, Ireland is Europe's largest producer of lead and zinc concentrates. To reduce dewatering costs and to improve environmental and working conditions, elimination of the lead concentrate thermal dryer was required. This paper describes the development and implementation of the pressure ceramic technology at Tara to replace a conventional vacuum filter/oil-fired dryer system. In 1996 the pressure ceramic filter dewatered 66,600tonnes of lead concentrate, producing a cake at 6 % moisture. Substantial operating cost savings have been realized. Commissioning of a second pressure ceramic filter to handle over 300,000 tonnes/year of zinc concentrates is scheduled for the first quarter of 1997.

Jan 1, 1997

By J. A. Luppens

Five years ago, Phillips Coal Company decided replacing mainframe/workstation programs with a new package of PC software was clearly the best solution for computer reserve modelling. The system chosen was actually three programs distinguished by their power, cost, flexibility and integration, and ease of learning and use. Phase I involves the use of the "StratiFact" program for borehole data management and seam correlation. This phase is probably the most neglected, yet critical aspect of reserve evaluation. Phase II employs the "PC/Cores" package for modelling and volumetrics. Phase m is "PC-Cut" which provides mine planning tools including an automated cut generator.

Jan 1, 1996

By Kal V. S. Sastry

Mathematical and expert system models are being used extensively for mineral process engineering. There exist no standardized methodologies for their computer implementation. In meeting this need, this paper introduces the concept of a process software model, or simply a software model and presents a two-step methodology for its development involving software model specification and development. The software model specification is to be performed after extensive discussions with the ultimate users of process software based on which the software model is developed. These software models provide a formal basis for the design and construction of software objects corresponding to the real world process objects.

Jan 1, 1994

By Dermot M. Ross-Brown

The more important factors controlling the design of pit slopes are related to the local geology over which the designer has little or no control. Nevertheless, there are some factors over which the designer does exert some control and these concern the say in which the rock is excavated and supported. They include blasting, face cleaning, water control, and the use of rock improvement techniques. The paper discusses these factors and relates the extra costs incurred to the steeper slope angles that can usually be obtained. It is demonstrated that even a modest increase in bench angle of 5° through improved excavation techniques can pay off in a single push-back.

Jan 1, 1975

By A. W. Jenike

Mine backfilling is a desirable method for the disposal of retorted oil shale. Hydraulic, mechanical and pneuna.cic transport and stowing methods were investigated, and the mechanical transport and stowing method using conveyors was selected as the most promising system. Transport of retorted oil shale at the rate of 3000 cons per hour (2700 t(h) to the backfill level, situated about: 2000 feet (610 m) below surface, with skips or conveyors is uneconomic. Hence, borehole transport utilizing gravity flow was investigated. This paper describes the theory of flow, flow properties of retorted oil shale, and the design of a borehole and hopper system.

Jan 1, 1978

By P. A. K. Wilkinson

This paper is concerned with the development of an in situ recovery of boric acid from a deep-seated colemanite deposit in California. The deposit contains 147 million tons of borate ore containing 6.4% boron oxide (B203). It is the largest undeveloped colemanite deposit in the United States and because of its unique occurrence and grade, in situ extraction appears to be the most economic viable process. The paper covers the geological, mineralogical, hydrological, well-field development, and extraction considerations leading to the initial pilot plant and subsequent demonstration plant phases of the project. Market potential aspects and preliminary economics of the project are also covered.

Jan 1, 1987

By L. 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 kreiging. The approach provides a filtering method that refocuses attention on the adequacy of drill hole spacing.

Jan 1, 1985

By Robert P. Larkin

The necessity for mineral extraction and its impact on man and the natural environment is a subject of increasing concern to Americans. Rising living standards and new demands for energy require increased mineral extraction, whereas the "new environmentalism" and concern over social well-being warn of the dangers to both the environment and the social system. This dilemma can only be solved by a complete understanding and analysis of all the factors relevant to human welfare which include environmental considerations, economic implications, and the social and psychological dimensions. A decision-making framework is therefore necessary which will encompass all relevant views of the problem.

Jan 1, 1975

By C. M. Walck

The Rosebud district is located in the Kamma Mountains, southeast of the townsite of Sulphur, Nevada. Since discovery in 1989, LAC Minerals, in joint venture with Equinox Resources, has delineated a resource containing approximately 570,000 ounces of gold and 5,500,000 ounces of silver. The deposit is of the volcanic-hosted epithermal quartz-sericite type. Mineralization occurs in tabular zones in and along the hanging wall of the South Ridge fault, and in cross-cutting high-angle structures. Multiple stages of discontinuous stockwork gold-and silver-bearing quartz-calcite-clay veins cut variably clay-altered, silicified, and sericitized rhyolitic Miocene volcanic rocks.

Jan 1, 1993

By Ernest L. Bradley

A positive pressure ventilation system, augmented by a dewatering well curtain and underground longhole drilling, provides effective ventilation and radon control at EXXON Minerals Company's Highland Underground Mine in the Southern Powder River Basin of Wyoming. Testing different types of bulkheads, sealants, and bleeder systems has led to improvements in the basic ventilation system. Continued testing of new or different materials and equipment is expected to lead to further improvement in the ventilation program. Effective training of both miners and supervisors is essential to maintaining and improving ventilation techniques. This paper addresses the ongoing ventilation program and experience to date at the Highland Uranium Mine.

Jan 1, 1979

By V. R. Manukonda

Selective flocculation of iron ores is extremely sensitive to the type and the amount of soluble salts in pulp solutions. Chemical precipitation of alkaline earth ions combined with ultrasonic treatment deactivates their adverse effects without using any environmentally ill-defined reagents. The manner in which ultrasonic treatment affects starch adsorption on hematite, dissolution of quartz, and selective flocculation process was investigated. Selective flocculation tests were conducted in the presence of up to 400 ppm calcium ion on a quartz-hematite mixture by precipitation as calcium carbonate, and the role that silicate ion generated by ultrasonic treatment plays in achieving the selectivity of separation is discussed.

Jan 1, 1987

By T. Szwilski

The Appalachian coal region is an area here the small mining operation dominates. The large number of small operations makes the coal industry in chat area very competitive, the industry concentration ratio being low. This feature is reflected in the nature and behavior of the coal supply and demand viz a viz the coal market. The vast majority of the small coal operations in Eastern Kentucky for example, are contractors. The circumstances under which a large mining company can elect to use contractors to supplement their coal production are examined. The pros and cons of small underground single unit mines and larger multiple unit mines are discussed.

Jan 1, 1986

By John Hughes

Fundamental to the use of rotary bit drilling equipment for oil and gas drilling is the requirement to maintain a cooling and lubricating environment for the bit and a means of conveying the cuttings from the drilling operation to the surface. The vast majority of such functions are provided for by the use of water based drilling fluids, commonly known as the drilling mud. One of the basic constituents of drilling mud is bentonite, a montmorillonite clay. Bentonite, when mixed with water at approximately 6% solids, will produce a fluid which has several important features in connection with its role as a drilling mud:

Jan 1, 1983