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By J. B. Mitchell

Comminution methods for base metal and precious metal ores have had considerable attention from mine operators, equipment suppliers and design engineers for many years and much of their work has been well reported. This interest derives from a healthy concern with the costs of comminution, often the largest single cost factor in ore dressing of hard ores. Many imaginative innovations have resulted. One notices a trend toward autogenous and semi-autogenous methods, combined with a trend toward very large equipment. Unfortunately, there has been less obvious cost incentive to experiment with softer ores. This is unfortunate because the consequences of inappropriate comminution methods can have an important effect on overall economics by influencing down stream processing and salability of final products. This paper concerns some of the factors to be considered in the selection of comminution methods for potash ores, and gives some specific examples to illustrate some of the principles involved.

Jan 1, 1969

By R. D. Herron

Mining coal under deep cover conditions is certainly the proper phrase to use in describing one of our newest operations. Located in the southwest corner of Virginia is this operation which is the Beatrice Mine of the Beatrice Pocahontas Company, a joint venture of Republic Steel Corporation and Island Creek Coal Company. The mine is working in the No. 3 Pocahontas seam in an assigned area of over 9500 acres containing over 60 million tons of recoverable, high quality, low volatile coal. The site of the mine opening was at Keen Mountain, Virginia, where the seam lay 1350 feet below the surface. This depth, greater than anything attempted thus far in the coal industry on this continent, would pose some problems, we felt, with which we had not previously had to contend.

Jan 1, 1968

By F. Soumis

This paper describes an integrated procedure for the very short term production planning of an open pit and the execution of this plan: the truck dispatching. Integration of plan and dispatch means that the plan is realistic so that its objectives can be realized by the dispatch. This realism is obtained by supplying the plan optimization, which involves mixed integer programming, linear programming and non-linear programming, with experimental O.R. models of waiting and blending. The arrangement of these models in the computer programm has made it possible to obtain very short computing time for the planning in spite of the width of the optimisation. The dispatching of a truck is made by solving a classical assignment problem for each dispatch over a horizon of the expected*next 10-15 trucks to request dispatches. This deep-reaching dispatch procedure uses the continuously arriving information about trucks' positions and shovels situations and models by probability functions the expected waiting time of shovels and trucks. In this manner trucks and shovels are synchronized and last moments' opportunities for productivity gains can be obtained. The dispatch procedure takes .5 second on PDP11. This integrated planning and dispatch procedure gives high productivity while ensuring good blending. Results from the Mount Wright mine of the Quebec-Cartier Mining Co., where the integrated procedure has been installed on the existing computer equipment PDP11, are included.

Jan 1, 1989

By Ronald E. Feltman

Most engineering firms engaged in the design and manufacture of milling components and systems have established, through the years, a relatively well defined system design procedure. The process design engineer has at his disposal several alternative approaches to the successful completion of this task. Unfortunately, while these alternatives, at first glance, appear to be rather straight Forward, any attempt to implement them into a fully integrated commuter design program becomes increasingly more complex when one addresses himself to the problem in total. This paper summarizes Kennedy Van Saun's approach to the solution of this problem through a planned system design. Following the problem definition and discussion, a detailed analysis and system design synthesis is presented; the major aim here being to provide a system design which may be programmed and run on a relatively inexpensive computer installation such as the IBM 1130 system currently in use at Kennedy Van Saun. A summary section is also included, which Provides a general outline guide to the program systems design of equipment which, while quite different from milling system functionally, nevertheless lends itself to the approach used in this paper.

Jan 1, 1969

By S. K. Kawatra

In order to meet federal air pollution guidelines, it is necessary to remove a considerable quantity of sulfur from many North American coals. This may be accomplished by oxidizing the sulfur to water soluble forms, followed by washing the coal. Selective oxidation of the various sulfur forms can be accomplished through the use of a variety of types of bacteria. In this paper, the various bacteria and their requirements are described, and processes using bacteria to remove coal sulfur are discussed.

Jan 1, 1987

By R. F. Harig

Designing an underground nuclear waste repository is a complex process. Although many decisions are involved before the design is complete, the first three--what the target horizon is, what the underground boundary is, and where the entry point will be located--are important because they establish the basis for the entire repository design. Even more important than these decisions, however, is the data on which the decisions are based. Because the current data are limited, an aggressive data gathering program is needed during the next design phase to augment information about the intricate interplay among all facets of the repository design and the geologic medium in which the proposed repository is to be developed. Although unique to modern engineering enterprises, the challenges involved in designing a repository in the unsaturated zone are within current technology and engineering practices.

Jan 1, 1991

By M. N. Herrera

The bioleaching of mineral sulfide pulps in a bench-scale rotating drum reactor has been studied. The reactor includes horizontal paddles in the inner wall for lifting of the mineral pulp. The performance of the reactor was tested in the bioleaching of a refractory pyritic gold concentrate in the presence of pure Thiobacillus ferrooxidans strain (ATCC 19859). The concentrate was efficiently bioleached at 50% pulp density with the drum operating at 0.5 -1.0 rpm Attempts of bioleaching the concentrate at the same pulp density in conventional stirred reactor showed severe inhibition of bacterial activity. The results demonstrated that the drum reactor allows to operate at much higher pulp densities than the conventional stirred tank reactor. This behavior is explained in terms of an improvement of the bacterial activity due to a better control of the attrition of the mineral particles.

Jan 1, 1997

By E. D. Hummer

During the planning phase of the fine coal cleaning addition at the Gary Coal Preparation Plant, careful consideration was directed toward the problem of minus 48 mesh refuse disposal. The plant flow sheet included wet screening the raw coal at 1/4 inch, pumping the minus 1/4 inch raw coal to bowl desiltors for desliming, and then cleaning the disliked raw coal on tables. The material to be removed from the circuit as minus 48 mesh refuse consisted of the minus 100 mesh desiltor overflow thickened in two 120 foot diameter thickeners and minus 1 mm screened from the table refuse. Later a flotation plant was added to recover coal from the desiltor overflow, and a classifier replaced the screens to make a sharper size separation of the table refuse at 48 mesh Today the minus 48 mesh refuse at Gary consists of thickened flotation tailings and thickened spiral classifier overflow. The transportation of large quantities of fine wet refuse filter cake mixed with jig and table refuse over existing conveying equipment would have been neither dependable nor economical. Filtration was therefore impractical, and disposal of the fine materials was a problem. The decision was to pump the material to storage ponds

Jan 1, 1965

By W. N. Brown

One of the seemingly eternal problems with which we are frequently faced is that of providing adequate and economical warehousing facilities to store large quantities of bulk product. Seasonal consumption, transportation, marketing, and other factors very often dictate extensive product warehousing requirements for an operation geared for steady, year-around production of a material requiring weather protection during storage. Fertilizers such as potash and urea are examples of such products; the consumption of these materials is extremely heavy in the early spring at which time the materials must be placed in the soil, whereas, for obvious operating efficiencies, production is more or less constant for a given operation throughout the year.

Jan 1, 1961

By C. M. Marquardt

The materials handling systems in the large concentrating plants have required the employment of a considerable number of workmen, many of whom had very little to do except to act as watchmen to avoid bad spills at belt junctions and to operate tripper cars, shuttle belts, etc. Much time also was spent in watching bins to make sure they were properly filled. Approximately four and one-half years ago the author, Yin coopera¬tion with the engineering and supervisory personnel of The Anaconda Company at Anaconda, Montana, began to give this problem serious consideration. Prior to this the author had developed, at the request of The Anaconda Company, a transistorized resistance-sensitive probe relay system for detecting the level of ore in bins. With this system cables or chains were suspended from insulators above the bins and were of suitable length to determine the elevation of the ore in the bins.

Jan 1, 1962

By Charles H. McGuirk

The movement of iron ore, limestone and-coal on the great lakes involves an intricate transportation network between mine, dock, vessel, railroad and consumer. The system requires that stockpiling be performed at certain points in the pipeline because of the seasonal closing of the lakes, traditionally, this has been accomplished at origin and destination with a substantial cost. Impact to both the shipper and consumer, From the time that the raw material is removed from the ground, expeditious handling and movement to final destination is threatened by a series of potential delays. An initial movement from mine or processing plant to the upper lake port must be coordinated between rail equipment and dock facility, As each vessel is loaded, a schedule must be developed which routes the cargo to an unoccupied lower lake port. However, if the vessel is not delayed by unpredictable weather conditions on the lake, the boat may still arrive at a port congested with other vessels awaiting their turn to unload.

Jan 1, 1973

By S. P. Singh

In order to understand the intricate nature of blast damage mechanism and to counter the associated problems, small scale blasting experiments were performed on hydrostone, concrete and granite. This was followed by a 2.4 m x 2.7 m (8'x 9') drifting operation in a quartzite quarry. Interior as well as exterior damage was assessed by different techniques. On the basis of the experimental results, the effect of explosive characteristics on the damage was examined.

Jan 1, 1992

By P. Walshe

A common belief among Itlnl.ng operators today is that computer based truck m:mitoring and dispatching systems are only applicable to, or affordable by, very large scale open pit mines. Before the advent of microcomputer technology this belief was generally a valid one. Microcomputer technology as it currently exists has reached a high level of sophistication and capability, rapidly approaching that of the minicomputer standard. When coupled with reliable software and data communications packages, it now provides the means to make truck monitoring and dispatching a viable and attractive management aid to mines of all sizes. This paper briefly addresses the evolution and current state of computer truck dispatching and examines a microcomputer based system in this context. To demonstrate the effectiveness of this approach to truck dispatching a recent installation in a medium sized mine is presented. Preliminary field data from the case mine are presented to illustrate the methodology.

Jan 1, 1989

By M. P. Fahey

A significant amount of silca is recovered in the rougher stage of anionic flotation of Florida apatite. This recovery, in the past, has been attributed to both entrainment and cation activated flotation. This study shows that by using a transport factor, it is possible to determine the contribution of each mechanism towards silica recovery. Further, it is shown that the concentration of cations in the conditioning water significantly affects both the amount of silica recovered due to entrainment and true flotation. Further confirmation of this phenomenon was obtained by Ca++ doping of the conditioning water and by using a sodium silicate depressant.

Jan 1, 1996

By George F. McIntyre

The subject of this paper is mineral processing chemicals - how they work and where they end up environmentally. First of all, it is necessary to recognize that water is the most universally and widely used chemical used by the mining industry to separate desirable minerals from unwanted wastes, sands, and slimes. Of the total world's water supply, over 97 percent is found in the oceans. Another two percent is tied up in the ice caps, leaving roughly only one percent for us to work with. This one percent is distributed either as ground or surface water and makes up the bulk of all water used industrially. Even with such a small proportion available for immediate use, there appears to be enough fresh water to meet our needs for at least another hundred years. This availability, however, depends heavily on how we handle our waste waters, how we process them, and how we plan for their reuse. Certain governmental agencies have been charged with the task of setting up standards of water quality which must be met prior to environmental discharge. There is even discussion of zero discharge from industrial operations. Due to limited supply and availability, the mining industry has always been forced to reuse its process water or to treat it prior to discharge. Consequently, we are in an enviable position and are presently able to live with the environmentalists demands. To stay on top of the situation, it is necessary to continually concern ourselves with the .effects of changing orebodies and reagents on the final mill effluent. From a process standpoint, it is also important to recognize the impurities of plant recycle water and how they might tend to influence overall operations

Jan 1, 1974

By J. F. Brune

"Re-occurring face ignitions in U.S. coal mines are concerning and require a closer look at air quality monitoring systems and practices employed in these mines. The explosion disaster at the Upper Big Branch mine in West Virginia in 2010 caused 29 fatal injuries and was largely caused by inadequate water sprays and inadequate ventilation monitoring. In this comparison, the author compares ventilation system monitoring in Australian, German and U.S. underground coal mines and makes recommendations for improvements and best practices. Mines in Germany and Australia are adhering to more stringent requirements for monitoring air quality and quantity and for monitoring water spray systems on cutters to prevent frictional ignitions. Air quality should to be monitored for sufficient oxygen, toxic gases, explosibility and for fire gases indicating a potential fire. Ventilation monitors must also confirm that sufficient quantities of air are available. Fully automated, continuously recording atmospheric monitoring and alarm systems are established practices in Germany and Australia and should be mandated for U.S. mines as well, in addition to the current, regular spot inspections of the ventilation system by certified mine examiners. BACKGROUND: METHANE EXPLOSIONS, FACE IGNITIONS AND NEED FOR AIR QUALITY MONITORING Accumulations of methane in face areas of underground coal mines frequently lead to ignitions that can cause burns, traumatic injuries and, in the case of the 2010 Upper Big Branch disaster, cause major explosions with multiple fatalities. Table 1 shows the number of reported face ignitions in U.S. coal mines between 2010 and 2014, based on statistical data published by MSHA (MSHA 2010 – 2014). Although there appears to be a downward trend in such ignition incidents over time, ignitions continue to occur with some regularity; and each ignition may cause a potentially catastrophic mine explosion.Per regulation, all U.S. coal mining machinery, continuous miners and longwall equipment, is outfitted with continuously monitoring methane sensors wired to cut power to the equipment as the methane level exceeds 1%. Face ignitions keep occurring because these sensors are usually not positioned in sufficiently close proximity to the coal cutting drums or to the freshly exposed coal face where the methane is most likely released. Therefore, methane may accumulate in explosive concentrations near the coal face and the cutting drums long before the gas concentration reaches the 1% level near the monitor and creates an alarm."

Jan 1, 2016

By Robert G. Beverly

The presence of radioactivity in uranium mill wastes has resulted in somewhat unique waste disposal methods. In addition to the common problems of disposing of large quantities of solid wastes, neutralizing acids, minimizing dissolved heavy metals, and clarifying all liquid effluents, the uranium mill operator must sample and analyze liquid effluents for micro-micro quantities of radionuclides such as, radium-226, thorium-230 and lead-210. Special disposal methods or decontamination procedures are required to meet the stringent limitations established by the U. S. Atomic Energy Commission on the concentration of radionuclides in liquid effluents. Routine monitoring of the receiving stream is also normally required. In recent years there has been a growing concern about the radioactivity remaining in the uranium mill tailings, particularly at the sites of shut-down or dismantled mills. The State of Colorado, in cooperation with the industry, has adopted regulations for stabilization of inactive uranium mill tailings. The Mining and Metals Division of Union Carbide operates mills for the recovery of uranium and vanadium at Uravan and Rifle in Colorado and a mill in the Gas Hills of Wyoming for uranium production. The company also owns former mill sites on which mill tailings are located at Maybell, Rifle, and Slick Rock in Colorado and at Green River, Utah. The purpose of this paper is to describe the methods used by a few uranium mills, largely those operated by Union Carbide Corporation, to dispose of radioactive wastes, to discuss briefly the regulations under which the mills operate, and to present reference information on the subject.

Jan 1, 1968

By E. Watkins, S. J. Schatzel, K. Ajayi, V. Gangrade

The National Institute for Occupational Safety and Health (NIOSH) has been conducting research related to unconventional gas wells positioned in abutment pillars associated with active longwall mining in Southwestern PA. The Ventilation and Explosion Prevention Team at NIOSH is working toward predicting and characterizing a hypothetical casing breach and its effect on the safety and health of mine workers, gas well workers, and the general public. An important aspect of this research is to distinguish coalbed gas from shale gas in the mine environment as an indicator of a casing breach. Another noncoal gas source exists in the region in the form of underground gas storage fields which also have the potential to migrate towards mine workings. During a potential gas breach, the addition of excess natural gas to coal mine environments will exceed the anticipated ventilation loading and can create a mine explosion hazard. A methodology has been developed to distinguish these gas sources. Gas samples from the three sources were analyzed by gas chromatography, and interpretive methods were applied to distinguish the populations graphically and statistically. Bivariate plots using the hydrocarbon index and the normalized molecular ratios showed that the sources occupy different regions of the graphs. All samples of non-coal gas contained under 2% CO2, and all coal samples included greater than this amount. A multivariate T-squared (T2) test analysis relating comparing data in pairs showed a low p-value (dimensionality parameter) and a high T2 test statistic for all comparisons, indicating that these sources are different and distinct gas populations. Ultimately, stakeholders from the mining and gas production industries can utilize this method to identify gas sources and a potential casing breach.

Mar 2, 2022

By D. H. Davidson

The basic principal in the ISL process involves the recovery of metal values by moving fluids through rock instead of moving rock. The process combines surface and sub-surface operations, with the economic performance controlled by four major factors; rates of fluid injection and production from wells; the rate of mineral solubilization; the volume of rock swept by the fluid; and the volume of solution processed through the system. This paper discusses various technical and economic parameters affecting these four factors and how they impact project costs.

Jan 1, 1985

By A. J. S. Spearing, G. Bylapudi, K. Mondal

The mining industry is a major consumer of rock anchors in the United States. Due to the high humidity in the underground coal-mining environment, the rock anchors corrode and lose their load bearing capacity, which, in turn, reduces the life expectancy of the ground support. This creates operational difficulties and a number of safety concerns (Li and Linblad, 1999). Research on rock anchor corrosion has not been adequate in the past and the effects of several factors in the mine atmosphere and waters are not clearly understood. One of the probable reasons for this lack of research may be attributed to the time required for gathering meaningful data. Underground water samples from different mines in the Illinois coal basin were collected and the major chemical content was analyzed and used for laboratory testing. The corrosion performance of the different commercial rock anchors was investigated by techniques such as laboratory immersion tests in five different corrosion chambers and potentiodynamic polarization tests in simulated ground waters based on the Illinois coal basin. The tensile strengths were measured for the selected rock anchors taken every three months from the salt spray corrosion chambers maintained at different pH values and temperatures. The corrosion potential, corrosion current and the corresponding corrosion rates of the #5, #6, #6 epoxy-coated and #7 forged-head rebar steels, #6 and #7 threaded-head rebar steels were measured in the pHs of 5 and 8 at room temperature. The open circuit potential (OCP) readings of the different rock anchors were recorded in three selected underground coal mines (A, B & C) in the Illinois coal basin and the data compared with the laboratory electrochemical tests for analyzing the life of the rock anchors installed in the mines with respect to corrosion current measured.

Jan 1, 2010