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By W. R. Reed

NIOSH continues to conduct respirable dust control research for surface mine blasthole drilling operations. Research areas have included testing variables (shroud leakage area, drill deck cross-sectional area, shroud height, collector-to-bailing airflow ratio, etc.) that have the most impact on respirable dust control, development of a dust collector inlet hood, development of a dust collector dump point shroud, and testing of a small diameter water separating sub. This paper summarizes the results of the aforementioned research that has been completed. Additionally, past dust control research for drilling operations of both underground and surface mines completed by the U.S. Bureau of Mines, created in 1910 and incorporated into NIOSH in 1997, is reviewed.

Jan 1, 2008

By G. A. Dawe, E. G. Kelly

Because of the nature of the breakage in the Barmac vertical spindle impactor, the 80% reduction ratio is very small, so that when an energy efficiency is calculated from Bond's method, it appears to be very low. However, the product size distribution contains a high proportion of fines. It is argued that the production of these fines accounts for the high energy consumption, and Bond's method is modified to account for this, by considering the crusher to be, effectively, a number of smaller crushers in parallel, each having a different reduction ratio.

Jan 1, 1990

By E. Alan Haley

Accurate and economic control of line and grade on long tunnels, large structures, excavations and waterways, has been a problem to surveyors and engineers for decades. The conventional method of surveying, incorporating a level, transit, and a number of surveying technicians, has proven, in the past, to be a very expensive and time-consuming operation. Alignment with a laser has solved most of the problem. Figure 1. With the advent of the Perkin-Elmer Model 5620 Construction Laser, use of laser light is now both dependable and economically feasible for unlimited applications in modern construction and surveying. The laser projects a continuous, narrow red beam of brilliant light, providing a constant alignment reference, and will not interfere with operations.

Jan 1, 1968

By Barry A. Hillman

Respirable (PM-10) crystalline silica is regulated by the State of California as a carcinogen. The risk-management of this material by the State exemplifies the inherent problems in the development of regulations based on current risk-assessment practices. The influence of extremely conservative risk-assessment and risk-management can be expressed in economic impacts including the increased cost of production, reduced competition, increased prices, reduced employment and redistribution of income. This paper attempts to contrast theoretical risk- assessment and risk-management with current application using crystalline silica as an example. Based on health information pertaining to silica, the paper examines federal and State of California regulatory and public policy positions. Using current risk factors and empirical data for the Central Valley of California, the projected incidence of lung cancer in humans is examined. While such an analysis would project an extremely high incidence of lung cancer as well as silicosis, not a single case of either lung impairment has been recorded within the study area or throughout the world in the general population. This suggests that sound guidelines for the analysis of scientific information have given way to the assumption that virtually any information representing a substance as a carcinogen is to be considered valid with little or no qualification.

Jan 1, 1992

By Reinhold Schulze

Thiourea is being applied as an industrial leaching agent for gold and silver only in a few cases. A CIP technique was developed which eliminates most of the obstacles against its use. Mild conditions for precious metals stripping from the loaded carbon simplifies process conditions in comparison to cyanide CIP technique. Examples are given.

Jan 1, 1998

By P. D. Nora, M. G. Ranade

A statistically designed pot grate-kiln test program was conducted to determine the agglomeration process variables necessary for increasing the low temperature disintegration resistance (LTD) and reducibility (R40) of magnetite-based Empire acid pellets. The ASTM tumble index and compression strength were to be maintained at an acceptable level. Six process variables - bentonite addition level, preheat time and temperature, firing time and temperature, and cooling rate - were investigated within the constraints of the Empire plant. The bentonite addition level and firing temperature had the largest effect on pellet properties. The results of this program were verified during a plant trial. The target firing temperature at the Empire plant has been decreased for increasing the LTD and R40 of commercially produced Empire pellets.

Jan 1, 1987

By K. A. Natarajan

The relative significance of corrosive and erosive wear in magnetic taconite grinding is examined. The influence of different types of aeration, namely, nitrogen, air and oxygen on ball war was established for mild steel and high carbon low alloy steel balls. Ball wear data from dry and wet grinding tests are compared with those obtained in the presence of an organic solvent that does not promote electrochemical corrosion. 'Marked ball grinding, tests along with electrochemical measurements involving ball material and magnetite electrodes indicate that contribution from oxygen towards wear (corrosive wear) is relatively small and abrasive wear appears to be significant. Rheological properties of the slurry-appear to have an important bearing on the abrasive wear of grinding balls.

Jan 1, 1983

By Kevin Sharman, Peri Mehling

A detailed assessment of acid rock drainage (ARD) potential was conducted at the Quintette Coal Mine site in northeastern British Columbia The site is unusual in that the coal seams contain low sulphur levels as compared to eastern coals (typically less than 0.5%), and the non-coal wastes generally do not to have the potential to generate acid on the basis of static ABA tests. The presence of small iron-stained seeps on the pit walls indicate localized sulphide oxidation, while the overall mine site drainage has remained of excellent quality with extremely low levels of metals after approximately 15 years of mining. Thus the site provides an excellent comparison to more problematic coal mine sites. For the Quintette assessment, static acid-base accounting (ABA) analyses of individual samples were compared to criteria for potentially acid generating materials developed for the U.S. Appalachian coal, as well as criteria developed in British Columbia for hard rock mines. Geologic units were characterized by the percentage of samples, or weighted thickness, that was deemed potentially acid generating (PAG). Links were then made to actual seepage and water quality emanating from geologic units around the site. Seeps at the site demonstrate a large range in pH (2.32 to 8.18). The few acidic seeps (pH < 4.0) were found to contain elevated levels of sulphates, dissolved iron, manganese and aluminum, consistent with the metals typically of concern in Appalachian coal mines. Other heavy metals that were detected in acidic seeps at Quintette included copper, zinc, nickel and cadmium. The use of simple ABA tests, and comparison of individual sample results with the Appalachian and British Columbia criteria, was found to be useful in predicting the probable sources of the small localized acidic seeps.

Jan 1, 2000

By Ricardo Gomez, C. T. Ogryzlo, A. A. Dor

This paper reviews the historical background leading to the development of the project. It gives a description of the exploration program and resulting geological and ore reserve information together with plans for mining. A discussion is included of the three processes investigated for the project: 1. Rotary Hearth and Magnetic Concentration 2. Shaft Furnace and Electric Furnace 3. Rotary Kiln and Electric Furnace Results of pilot plant campaigns conducted at Fiskaa, Norway, and Riddle, Oregon, on the process chosen for the production of ferronickel are presented. The paper continues with a review of the considerations involved in selection of commercial plant equipment and concludes with comments on the current status of the project.

Jan 1, 1979

By Hans Hamrin, Bruce Kennedy

Once an ore body has been probed and outlined, and sufficient information has been collected to warrant further analysis, the important process of selecting the most appropriate method or methods for mining can begin. At this stage, the selection is preliminary only, serving as the basis for a project layout and feasibility study. Later, it may be found necessary to revise the details, but the basic principles for the ore extraction should remain a part of the final layout. With respect to the basic principles employed, relatively few mining methods are used today. For the purposes of this presentation, the principles are classified as follows: 1) For naturally supported stopes, the available methods are room-and-pillar mining and sublevel stoping. 2) For artificially supported stopes, the available methods are shrinkage stoping, cut-and-fill mining, square-set mining, and longwall mining. 3) For caving methods, the available techniques are sublevel caving and block caving. Due to the uniqueness of each ore deposit, the variations on each of these methods are nearly limitless. It is impossible to include even the major variations in this chapter; the goal of this chapter is to present the principles as a guide to the mining engineer in adapting the general methods to specific needs. The selection process described herein is intended to supply the techniques by which the candidate methods available for a given ore body can be reduced to one or two feasible approaches. The feasible approaches then can be evaluated in detail, and the particular modifications can be investigated. In describing costs and economic factors, all values herein are expressed in terms of 1978 US dollars.

Jan 1, 1982

By C. McDonald, S. Slottee

Deep "paste" thickeners have been used in the alumina industry for several decades to improve chemical recovery and allow “stacking” of the red mud for disposal. These paste systems have eliminated many traditional tailings ponds in addition to providing better tails washing and better water recovery. This technology is not widely used or understood in other mineral processing applications. However, there is growing worldwide recognition of the advantages of concentrating mill tailings to a “paste”, i.e. a solid suspension that does not settle or segregate. This technology offers several alternatives to the traditional tailings pond such as “stacking” or mine backfill. More water recovery is possible than with high rate thickeners. Process benefits come in the form of better chemical and metals recovery through better washing in counter current decantation (CCD) applications. Obtaining a true paste (non-segregating suspension which exhibits a yield stress) and understanding the handling characteristics for applications outside alumina, are recent developments. Achieving all of the benefits available from a paste system requires careful design that takes into account the specific requirements of the disposal application along with the peculiar difficulties in producing and handling paste. In fact, design of a paste system is markedly different from a conventional system. Project design usually requires the cooperation of experts in several interrelated specialties including geotechnical, thickener design, pumping and discharge design and controls. A successful project must coordinate all activities to ensure that the overall objectives for the project are achieved. This paper describes the properties of paste, reviews the applications, and discusses the design of a complete paste deposition system.

Jan 1, 2003

By Marion A. Goudie

The Devonian salt basin, which contains the Saskatchewan Potash deposits, extends from just east of the foothills in Alberta, north as far as the Peace River area, across Saskatchewan and into Manitoba as far east as Range 10 west of the First Meridian and south into Montana and North Dakota. The basin is closed everywhere except to the northwest. The known potash deposits are confined almost entirely to the Province of Saskatchewan, with the exception of a small area in western Manitoba bordering the Saskatchewan boundary. The following discussion will concern only the Saskatchewan part of the basin. The evaporite series in the basin is defined as the Prairie Evaporite Formation of the Elk Point Group, of Middle Devonian age. Recent work done by potassium-argon dating methods has indicated an Upper Middle Devonian (Givetian) age of from 265 to 347 million years for the potash. The Elk Point Group consists in ascending order of the Ashern, Winnipegosis and Prairie Evaporite Formations. The Ashern formation, sometimes called the Third Red Bed, consists of dolomitic shales or shaly dolomites. The Winnipegosis is a reef type dolomite, usually with good porosity, and in many cases oil-staining, although to date no production has been obtained. The Prairie Evaporite formation consists of anhydrite overlain by halite and finally, in Saskatchewan, by the potash beds. In almost all wells which have been cored for potash the lowest potash bed is underlain by one or two bands of anhydrtte, which are used as marker horizons. Cores from a few wells which cored to the bottom of the salt series have shown flecks of potash throughout the halite.

Jan 1, 1959

The value of US industrial mineral output last year was $20 billion, a 12% decline from 1981. A glance at the accompanying table and a review of the comments made by several contributors reveals how poorly many industrial minerals fared during 1982. Bromine and peat posted a 6% increase in production while recovered sulfur showed only a 3% gain over 1981. Pumice, salt, and dimension stone managed to stay more or less even with 1981 production. However, most industrial minerals posted losses for the year from 3% for vermiculite, sodium carbonate, and gypsum to 49% for ilmenite. Naturally, the depressed economy is to blame for decreased production and consumption. Low steel and auto production, lower housing starts, and many other factors impacted the industrial mineral industries. Hopefully the worst is over. Interest rates are down, energy costs are decreasing, the automobile and housing industries show signs of picking up. Perhaps the 1983 annual review will be less gloomy. Many thanks to these industrial minerals technical committee members for their contribution to this year&apos;s annual review: G. S. Austin, E. S. Montgomery, H. P. Ehrlinger III, D. B. Jorgensen, R. L. Parratt, J. F. Burst, W. Mallory, N. C. Trivedi, and N. K. Olson.

Jan 5, 1983

By Lucien Duckstein

The purpose of this paper is to give recommendations for utilization of water resources in a mining region, considering also water supply and environment; the case study of mining for coal and bauxite under the karstic aquifer of the Transdanubian mountain of Hungary is used to illustrate the approach, which consists in formulating a static multiobjective control model and solving it by compromise programming. The three activities of regional mineral resource exploitation, water supply and environmental protection are represented by different objectives which cannot be expressed in commensuerable units. Thus, a solution which is optimal for one objective is usually far from being optimal with respect to the other two objectives. As a result, we are not seeking an optimal solution for the conjunctive regional system, but a good compromise, trade-off or "satisfactum" (1), (2).

Jan 1, 1979

By T. E. Wilson

The length of Alaska&apos;s coastline, combined with the presence of a significant number of fjords, encourages consideration of marine disposal of mine tailings. However, the decision-making process is complex because various factors govern the viability of the submarine tailings disposal (STD) option. An expert system, called the Submarine Tailings Disposal Expert System (STADES), was developed to help mining project planners explore the feasibility of STD. A review of the existing literature, supplemented by engineering recommendations, on the various aspects of the marine disposal of tailings formed the knowledge base for the expert system. The shell used to develop the expert system was LEVELS.

Jan 1, 2003

By C. A. Hollingsworth

The Deep Leg Flotation Cell was developed to solve a problem which confronted the Smith-Douglass Company on moving from one mining area to another. Poor recovery and, to some extent, inferior concentrate grade were encountered in the silica flota¬tion circuit. This was believed due to the softness of the phosphate which caused it to form slime. In view of the urgency of the matter, the problem was attacked from two angles. The first involved the development of a flotation cell which would not create slime and the second, a new or improved reagent for floating silica from phosphate rock which would be less sensitive to slime than reagents currently in use.

Jan 1, 1964

By Robert Stefanko

The importance of underground stress instrumentation cannot be minimized. It was Lord Kelvin who said that unless you can assign a number to a quantity,, you know very little about it. Most engineers will agree although this kind of statement is resented by our friends in non-technical fields. Mining is undergoing a revolution from art to science. But how can mining methods be optimized if there is no way of measuring the effectiveness of a given mining method? Do we know how effective a&apos; support is unless we can determine its reaction to the mine structure? How do we assess the need for modifications to existing systems and supports, and how do we measure the effectiveness of such changes? Cut and try techniques are too wasteful of time and energy, and rarely provide solutions to a given problem. The purpose of underground stress instrumentation is to provide answers to some of the above questions -- answers that cannot be obtained otherwise This does not mean that laboratory studies are not valuable -on the contrary. Laboratory and underground studies supplement one another. Rock mechanics had its conception with the study of stresses in homogeneous, isotropic, and elastic models subjected to various force systems. These analyses were valuable inasmuch as they pinpointed possible sources of trouble due to stress concentrations. If the results observed underground did not always agree with the experimental analysis, it was not an indictment of the latter. More probably, the discrepancy could be attributed to the lack of similitude between model and prototype. The more nearly one can simulate underground conditions in a model, the more apt one is to produce results which correlate well-with underground observations. It is impossible to completely simulate underground conditions because all of the significant design parameters have not been recognized and evaluated. What better way can one evaluate these parameters than by underground stress instrumentation?

Jan 1, 1963

By Frederick W. Bauer

The potential worldwide "market" for metallurgical bauxite is about 94 million MT. The high degree of concentration of the alumina sector, combined with the high percentage of long-term contractual relationships, results in a small spot market with an illdefined price structure. Further segmentation occurs based on bauxite quality and alumina plant design. The potential &apos;free" market is estimated to be about 18 million MT that represent the requirements of nonintegrated alumina producers. It, too, is covered almost entirely by multi-year supply contracts.

Jan 1, 1984

By R. V. Ramani

Control is a vital management function by which operations are brought into compliance with predetermined standards to achieve the goals of an enterprise. Events that are characterized by a low degree of expectation, avoidability, and intent necessarily have a low degree of control. Such events are difficult not only to predict but to control as well. Fortunately, very few industrial situations fall into that category of events. It is an axiom of control technology that in order to control, one must first measure; further to measure, one must know the characteristics of the subject (or environment) upon which the measurement must be made. Finally, if measurements are to be made reliably, the influences that affect the measurement must be known and, if possible, understood. The complete control cycle therefore consists of the following: (1) defining the objective, (2) planning to achieve the objective, (3) putting the plan into practice with appropriate instructions, (4) measuring variables or parameters of interest, (5) transmitting and transforming the measurements to analyze the system&apos;s status and to predict the future outcome, (6) comparing these with the defined objective, and (7) determining and taking corrective actions to bring the actual results closer to the objective. The management principle underlying the control cycle is the principle of management by exception. The application of the principle and the frequency with which corrective actions are taken vary according to the purposes of the review and control. For example, the control of a machine operation (e.g., truck on a haul road) may require adjustments and therefore data, analysis, and decisions, in intervals of seconds whereas the review for ore-grade control may take several hours. Reviews, on the other hand, for cost control may be done in intervals of weeks or months. In any case, three specific purposes of the control cycle are: (1) to correct the operation so that it follows the accepted plan closely, (2) to evaluate the operation and predict future outcomes in light of changes in the environment or of more experience, and (3) to review the objectives and modify these to be reasonable and realistic.

Jan 1, 1979

By B. Andersen, P. Somasundaran

An accurate knowledge of the interactions among mineral particles and between such particles and dissolved and precipitated species is important in developing efficient separation processes. In this investigation, interactions relevant to dispersion and selective reagent adsorption (the two main prerequisites for selective flocculation) within Florida phosphatic clay Waste were studied. Initial studies with artificial slimes, consisting of pure clay and phosphate minerals, showed dispersion of artificial slimes to be relatively easy. The problems that were encountered during selective flocculation of the artificial slimes were due to unselective polyacrylic acid adsorption on clay, which was caused by the presence of multivalent calcium ions on the exchangeable cation positions on the clay surfaces. This problem could be solved by exchanging calcium for sodium, which reduces the interaction between the polymer and the clay surface. This procedure, however, was not successful for mineral mixtures. Natural slimes were found to be much more difficult to disperse. This was attributed to the presence of cementing materials such as humic substances and Al and Fe (hydr)oxide precipitates. Selective removal of these cementing materials resulted in good dispersion and partial separation. A further increase in the separation of natural slimes is most likely determined by the presence of calcium on the clay surfaces, as was found for the artificial mixtures.

Jan 1, 1994