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By E. R. Bauer

A primary goal of Ground Control Research, Bureau of Mines, U.S. Department of the Interior, is to develop information that can be used by the mining industry to reduce accidents and fatalities due to failure of mine roof. A specific research objective is to determine methods to detect hazardous coal mine roof. This paper reviews the existing and experimental techniques, and describes a recent Bureau of Mines contract research project that resulted in a simple technique and prototype instrument for evaluating mine roof competence.

Jan 1, 1986

By M. A. Alan

The Bellavista Gold Deposit lies 75 Kms north west of San Jose, the capital of Costa Rica, Central America and 3 Kms north east of Miramar, in the Province of Puntarenas. The total road distance from San Jose to the deposit is 120 Kms all paved road except for a 2.5 Km graded, gravel road on the property (Figure 1). Infrastructure services in the Miramar-Puntarenas area are well developed with electrical power distribution, a modern port facility and community services being available. The deposit lies on the south west flank of the Tilaran Mountain Range between an elevation of 550 and 800 meters above sea level. The local topography is steep, originally covered with pre-montaine, tropical wet forest vegetation which has been largely destroyed due to clearing for cattle grazing. The annual rainfall is approximately 2,950 mms, 90% of which occurs between May and October.

Jan 1, 1992

By D. D. Rabb

Originally, the term solution mining applied to a dissolution, washing, or "brining" of soluble salts such as halite (common table salt), potash or trona. After the mid-sixties, however, the definition has been expanded to include heap and dump leaching, in-place (in situ) leaching, removal of oil from tar sands, extraction of sulfur from deep wells by the Frasch process and the recovery of metalliferous solutions from geothermal sources. Solution mining is also known as borehole, non-shaft, or chemical mining; the extraction of soluble mineral values from a variety of ores using appropriate solvents and chemicals. Solution mining frequently involves chemical changes; for example, copper usually goes into solution as copper sulfate, gold and silver as a cyanide compound, and uranium as a sulfate or uranyl tricarbonate. The valuable constituent is removed from the solid body of the ore by mass transfer to a aqueous solution.

Jan 1, 1986

By D. G. Chedgy

Careful consideration is given to the type of cleaning equipment and control sys- teas to be used when selecting circuits for wash-ing fine coal (28M x 0 size fraction). However, the desliming, declaying and sizing procedures required to ensure efficient operation normally are not evaluated in sufficient detail resulting in disappointing system performance. This paper details desliming and dewatering circuit design which is extremely effective based on recent test data. The circuit maintains control of the 28M x 0 (declayed) size fraction with minimal misplaced material and maximized circuit efficiency. A discussion of circuit design parameters and control systems, as well as results from the testing program, are included in this text.

Jan 1, 1986

By Michael Gauna

A high seam geologic condition exists at Jim Walter Resources No.4 mine which requires immediate rib support after a continuous miner cuts a place, High seam mining heights are typically 2.4 to 2.6 m (8 to 9 it) and a thick rock layer is present in the upper portion of the coal rib side. The 610 m (2000 ft) mining depth at No. 4 mine induces horizontal rib line movement after excavating an entry. Horizontal rib movement greater than 30.5 cm (12 in) have been noted. When lateral movement occurs in the high seam areas, the thick rock layer, and the coal above the rock layer, become fractured and tend to roll into the entry. If not adequately supported, large rib rolls develop in the place being bolted as well as in previously mined areas which endanger men and equipment. To control this situation rib support must be installed in the roof bolting operation as the bolting crew works towards the face. A rib control system has been developed for this high seam mining condition utilizing a mechanical anchor bolt placed at an angle in the rib and installed with a modified Fletcher DDFI- 15 bolting machine. Over 120 km (75 mi) of entry have been supported with angle rib bolts. These angle bolts constitute 43 to 60% of the total roof and rib bolt footage in the high seam port- ions of No.4 mine. The angle rib bolting system has proven safer, more effective, and more efficient than the earlier support method employing bolts installed horizontally into the rib. No rib roll accidents have occurred since the angle drill bolting machines were placed in service in 1981. By securing the broken rib material with an angle bolt anchored above the coal pillar, a more effective means of rib control is achieved. Angle rib bolting does not interfere with continuous miner productivity. In addition, bolting crews are now reduced from three to two people and the total drilling supply costs are approximately 60% the previous cost, when compared to the previous support method using horizontal rib bolts.

Jan 1, 1983

By C. William Parisi

Since the introduction of mechanical mining, some 35 years ago, a great deal of effort has been expended by the coal industry to solve the coal dust problem. The original concern was the possibility of a dust explosion or the propagation of a gas ignition; however, in recent years it has come to be recognized as a possible 'health hazard as well. In the middle thirties, the Pittsburgh Coal Company began an intensive study of the dust problem to determine the dust levels created by the various cycles of operation in mechanical mining and to make a comparison with those of hand loading operations. Numerous dust samples were collected with a midget impinger and it was found that dust counts varied from 38 to 268 million particles per cubic foot during hand loading and from 96 to 227 million particles per cubic foot during mechanical loading. The study indicated that the source of underground dust in coal mining could be classified as primary or secondary. A primary source is one associated with appreciable degradation of size, that is, where most of the fines capable of becoming air-borne are produced. A secondary source is one in which most of the fines have been produced at some previous operation and are in such condition that they can become air-borne. Cutting, drilling and blasting are the operations which produce the primary dust. Secondary dust is formed by operations which include; loading, transportation and discharge at transfer points. The study showed clearly that the coal cutting operation was responsible for the greatest amount of dust and that the amount of dust produced varied directly with the speed of cutting; type and dullness of cutting bits; and the distance the cuttings had to fall to the floor. The information obtained from the study enabled our company to decide on a course of action and the direction to follow. With the cooperation of mining machine manufacturers, water tanks with a 200 gallon capacity were built into the machine trucks and were provided with a pump driven by a small motor. A length of 1/2" water hose carried the water from the pump to the two water spray nozzles located at the front of the machine. Water was delivered to the machine tanks by water cars which were filled on the surface or from an underground water supply. It was during these early days that wetting agents were introduced into the water system. Our studies revealed that wetting agents did little better than plain water in the abatement of the dust problem. It was found that when using a wetting agent less water was required to obtain the same results but we could not take advantage of this fact because it was almost impossible to keep the smaller nozzles open to reduce the amount of water being used.

Jan 1, 1967

By Michael J. Fiannaca

Disseminated epithermal gold metallization occurs within a breccia unit interpreted to be a submarine debris flow. Cold is associated with oxidized pyrite, fluorite, and jasperoidal silica. A minimum of 9 million tons of open-pittable mining reserves will be cyanide heap leached as run-of-mine ore at a rate of 1.0 million tons per year. Careful evaluation of the combined results of successive sampling projects has established the pit plan, mineable reserves, and process metallurgy of the operation. The sampling procedure utilized for a given test depended upon geological interpretation as well as the procedures, successes, and failures of previous tests. This paper summarizes the sampling and testing procedures of the development effort in light of the project goals and attendant problems in achieving them.

Jan 1, 1984

By David K. Hylbert

This study investigated roof falls in room-and-pillar drift coal mines in eastern Kentucky and utilized geologic methods for predicting roof conditions in advance of mining. In the Highsplint mine, the roof was classified in four categories or conditions: Condition A and B (Laminated Shale), Condition C (Rolling Sandstone with Shale in Pockets) and Condition D (Zone of Major Sandstone Roll(s)). Structure contour and isopach maps of the Darby coal bed and associated immediate roof rocks were used to project axial trends of the sandstone roof. Trend mapping in the mine and on outcrop provided more detailed control for roof projections.

Jan 1, 1978

By C. Y. Chen

In order to put an end to the uneven environmental standards and enforcement established by various coal mining States in the United States, the Congress passed and the President signed the Surface Mining Control and Reclamation Act (Public Law 95-87 or the Act) on August 3, 1977. Within one year after passage, the Secretary of the Interior was directed to promulgate permanent program regulations implementing Title V provisions of the Act. These regulations were to form the basis for State regulatory programs under the Act and to allow States to assume primary regulatory responsibility. In order to implement the underground mining provision of the Act, the Secretary is directed in section 516(a) of the Act to promulgate rules, but ones which take into consideration the distinct differences between surface coal mining and underground coal mining. The regulations developed by the Secretary and promulgated on March 13, 1979, with respect to subsidence control, included (1) a subsidence control plan as part of the permitting process, (2) substantive provisions establishing performance standards for subsidence control, and (3) provisions providing for the prohibition of mining under perennial streams, impoundments larger than 20 acre feet, and certain public facilities and urban areas.

Jan 1, 1985

By W. G. Kegel

The past few years have produced a rash of demands for changes in America's way of doing things. From manufacturer to consumer, the rules have been changed. Some of the demands were needed and, when legislated to requirements, did manage some good for all concerned. Other demands made by zealots and taken up by regulatory agencies have forced costly changes on our way of life. No segment of industry has been exposed to more new rules and regulations than the deep coal mining industry in the United States. There is no denying that some good has evolved, but most mining men know that the effects have done more to reduce production and increase cost than they were ever intended to do.

Jan 1, 1975

By Allan Gebhard

The purpose of this paper is to summarize the role of water resource monitoring in mining activities and to discuss the considerations that go into designing and implementing a monitoring program. The design of a monitoring program is invariably based on sound engineering and scientific judgement since no design formulas exist that can be universlly applied to the monitoring of all activities. As discussed in this paper, however, a methodology of designing a water resource monitoring program does exist. In order to cost-effectively monitor the water resource impacts of mining activities, the following three monitoring related items should be understood: 1. the role of water resource monitoring in the planning, construction, and operational stages of mine development, 2. the available water resources monitoring methods and the proper role of each method in the various scages of mine development, and 3. the strategies that should be followed in designing and implementing a water resource monitoring program.

Jan 1, 1976

By S. R. Titley

Results of regional analyses of precious metal habits in Arizona ores lead to interpretations of a fundamental ore control related to geographic location that corresponds with crustal contrasts. Measurements of isotopic and trace element characteristics of Laramide ore-related intrusions lead to interpretations of crustal derivation of apparent ore-related magmas. Interpreted regionally, the numerous kinds of Laramide ores, which include porphyry copper deposits of this southern cordilleran region appear to be phenomena of a specific crustal lithology characterized by a basement of Proterozoic turbidites and (an interpreted) lower crust of amphibolite. This association with a specific basement terrane may be extended in principle from the United states into Mexico where faulted offsets of this basement are similarly favorable to formation of Laramide porphyry ores -to the exclusion of adjacent terranes. Whereas plate tectonic mechanisms may have triggered evolution of these ores, it is hypothesized here that crustal setting and crustal composition are more profound influences of metallogenesis.

Jan 1, 1992

By Ronald L. Wiegel

In the 2000 page Handbook of Mineral Dressing by A. F. Taggart, the subject of material or metallurgical balances is covered in only six pages of eve-straining type. Although Taggart's work was compiled before 1945, and there has been significant progress since then in most areas of mineral processing, the practicing metallurgist's approach to metallurgical balances remains exactly the same as described in those six pages. There are several portions of Taggart's text appropriate to introduce the subject of this paper which I would like to quote: "Milling Calculations. Computations of per¬formance in milling are complicated by the fact that it is a continuous rather than a batch operation, that the quantities of solid materials handled are large and usually mixed with water, hence difficult or impos¬sible to weigh. Fortunately it is possible to determine many facts concerning perfor¬mance without knowing weights, if the value of various constituents is known in some common unit, e.g., the content of some par¬ticular metal or mineral, or of water, or some ingredient soluble therein, or of par¬ticles of a particular size or falling within some particular size range, or the like."

Jan 1, 1979

By John L. Bolles

The Phelps Dodge Corporation's Morenci Concentrator includes facilities for coarse crushing, fine crushing, grinding, flotation, tailing, disposal, concentrate filtering, and drying. The Morenci Concentrator daily throughput is in excess of 60, 000 tons. The ore milled is mainly a medium-hard monzonite porphyry in which the principal sulfide minerals are chalcocite and pyrite. The ore is transported by rail from the Open Pit Mine to the primary crushing plant located at the concentrator site. Ore is side-dumped from 80¬ton railroad cars into a sixty-inch gyratory crusher. The ore is then conveyed to a. 12, 000 ton coarse ore storage bin. Fine crushing is accomplished by four parallel lines of conventionally stacked crushers in open circuit. Each unit consists of one seven-foot standard cone followed by two seven-foot shortheads. Ti% product of the fine crushing plant is distributed by two tripper cars across a fine ore storage bin. The crushed ore is then fed by variable speed belt feeders into thirty parallel, single stage, closed circuit grinding units. Each of the 30 grinding units consists of one 6' x 23' conditioning drum, one 10' x 10' ha l mill and two 54" duplex spiral classifiers as principal equipment. The dry ore is fed into the conditioning drum with water to dilute the ore to a slurry of approximately 78% solids by weight. An aqueous solution of ammonium sulfide is also added to the conditioning drum. The ammonium sulfide primarily acts as a sulfidizing agent. The ore slurry containing the naturally occurring sulfide copper minerals and the sulfidized copper minerals discharges into the feed scoop box of the ball mill, where milk of lime, collector and-.dilution water are added. The ball mill product slurry is gravity fed: to the classifier pool where water is added to obtain the desired classifier overflow product

Jan 1, 1977

By Brendan Demich, Linda L. Chasko, Brendan Macdonald, Timothy J. Orr, Jessie J. Mechling, Cassandra Hoebbel, Jason Navoyski, William Helfrich, Jessica Cohen, Paul E. Schmidt, Jennica L. Bellanca

The National Institute for Occupational Safety and Health (NIOSH) in partnership with the Mine Safety and Health Administration (MSHA) developed VR Mine Rescue Training (VR-MRT). It is a training platform that allows mine rescue team members to explore virtual emergency scenarios collaboratively. Team members use a head-mounted display to visualize and interact together with equipment, hazards, and dynamic ventilation. All player actions are recorded and displayed for debriefing. Researchers at NIOSH demonstrated the training platform at various mine rescue competitions, including the International Mine Rescue Competition, and collected feedback. Participants’ responses were overwhelmingly positive. This paper describes the development of the software platform and the results of the usability surveys and interviews.

Jun 25, 2023

By J. Mark Richardson

The use of an integrated software package to simulate and optimize the performance of mineral processing circuits is illustrated by three examples. Each represents application of the software and associated techniques to optimization of an existing plant. In the first example, a South-western U. S. copper company employs the method to simulate and improve performance in crushing, screening and SAG milling. A second copper producer evaluates equipment changes and flowsheet alternatives in a closed-circuit ball mill-cyclone operation. A Southeastern U. S. aluminum refinery optimizes performance of a dry milling and classification circuit for production of carbon particles used in anode casting. Graphical and tabular data describe the circuits simulated and the results achieved in each example.

Jan 1, 1990

By Wu Aixiang, Zhou Qian, Zhou Zaibo, Liu Juanhong, Wang Hongjiang

To improve the pumping capacity and engineering efficiency of fresh thickened tailings slurry, a high charge density superplasticizer was developed to improve the rheological properties of tailings slurry. The effects of superplasticizer content, the concentration and fineness of tailings, the proportion and type of cementitious materials, temperature, and hydration time on the rheological properties of unclassified tailings slurry and backfill materials were studied. The variation characteristics of the slurry yield stress, plastic viscosity, and thixotropy with different factors were measured by a Brookfield R/S-SST plus rheometer. The experimental results of fresh thickened tailings illustrated that the higher the concentration of the slurry and the finer the tailings, the worse the rheological properties of the slurry. The results of cemented paste backfill materials indicated that the rheological parameters increased as binder content and time increased. The rheological parameters decreased as the temperature increased. The addition of a superplasticizer reduced the rheological parameters and improved the rheological behavior of the fresh thickened tailings and cemented paste backfill materials, which was beneficial to the slurry’s pipeline transportation. This paper can provide technical guidance for slurry transportation in the backfill system and provide a reference for designing the superplasticizer used in tailings.

Jan 5, 2022

By Kathy Kalenchuk

To develop strategic and tactical strategies to manage seismic hazard in a safe and economic manner, it is necessary to understand the spatial and temporal distribution of mine wide seismogenic behavior. Global mine-scale numerical stress modelling provides a means to forward predict seismic susceptibility thereby facilitating informed decision making for the development and implementation of strategic and tactical risk mitigation measures. To make forward predictions of hazard susceptibility using global stress models with reasonable confidence, it is necessary to rigorously calibrate numerical stress models to the observed history of ground reaction. This paper demonstrates quantifiable methods for calibrating numerical models and developing probabilistic prediction criterion using seismic data. The appropriate applications of model inputs (including boundary conditions, constitutive models and material parameterization) specific to global mine-scale modelling are also discussed. Lastly, this paper demonstrates how the calibration process adds value not only to informed decision making, but also to the improved understanding of site geomechanical conditions; including enhanced identification of geotechnical domains and mechanical indicators required for seismic mechanism domaining.

Apr 26, 2022

By D. M. S. Bhatia

Five sulfide minerals from the Magiwnt mine, southeast Missouri were analyzed for 31 trace elements in over 300 samples by laser microprobe spectrographic analysis of polished sections. The concentration of several trace elements shows a pattern of progressive variation with depth (space) and variation with different paragenetic stages (time) of each mineral. Factor analysis of the geochemical data shows sympathetic correlation both in space and in time of Bi, Cd, Ge, and Sn in galena and sphalerite, and Ni and Co in sphalerite and marcasite.

Jan 1, 1979

By D. Malhotra

The effect of some of the reagents, namely hydrocarbon oil, Syntex (sulfated coconut oil surfactant), pine oil, sodium silicate, and lime, used at the Climax mill on the recovery and grade of molybdenite and gangue minerals has been investigated experimentally using factorially designed test approach in the laboratory. The results of the investigation are presented in two dimensional plots. The lower additions of lime (equivalent to a pH of 8 to 8.5) were desirable for maximizing recovery subject to constraints on grade. Higher additions of pine oil improved recovery, but only at the expense of grade. A mathematical model of the objectives of an operating plant was formulated and optimum reagent conditions obtained.

Jan 1, 1977