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By E. V. Deshayes, W. E. Young

"INTRODUCTION The Camp Bird mine was investigated by Bureau of Mines engineers 3/ September 22 and 24, 1942, and April 29 and 30, 1944. In a subsequent report and supplement, it was recommended that core drilling be done below the 14th. level to determine if commercial ore existed at greater depths, and particularly if ore existed in the vein or adjacent thereto where it passes into the sedimentary formations estimated to underlie the volcanics approximately 400 feet below the 14th level.Seven diamond-drill holes aggregating 3,956 feet were drilled. Four of these holes were under the Hematite ore body and three were under the Big Discovery ore body. Two holes under, the Hematite ore body wore directed at angles but little steeper than the angle of dip of the vein and penetrated the sedimentaries beneath the volcanics close to the vein. Enough low-grade ore was found at the base of the Telluride conglomerate to indicate the presence of a large body of low-grade zinc sulfide ore. Two holes were directed to crosscut the vein at a depth of approximately 125 feet below the 14th level. No commercial ore was cut, but the vein showed the average width and same general characteristics as at the 14th level. One hole under the Big Discovery ore body was directed to crosscut the vein and test the base of the Telluride conglomerate in the footwall block. No commercial ore was found in either the vein or the sedimentary horizon. One hole was directed to test the base of the Telluride conglomerate in close proximity to the vein in the hanging-wall block. This hole was lost approximately 100 feet short of its objective, and a third hole was drilled to accomplish this same thing. The third hole was stopped approximately 50 feet short of its objective when failure of equipment caused a recess of the"

May 1, 1948

By John C. Machisak

INJURY experience and employment data for the nonmetal mining industry in the United States are presented for the calendar year 1958. Statistical tables 6 to 12 give detailed information on injuries and employment at nonmetal mines. Data for nonmetal mines are presented separately from those for nonmetal mills, tables 23 29. The Bureau is authorized to send questionnaires to the nonmetal industry for their voluntary submission on of injury and employment experience at their operations. As this information contributes to the promotion of safety in the nonmetal mining industry, every effort has been made to make these questionnaires as complete as possible.

Jan 1, 1962

By R. W. Baker

"The development of uppers drilling at Brunswick Mining is reviewed. This paper describes design criteria for drilling patterns and the research required for selection of a suitable drill jumbo. The success of the uppers drilling program based on operating procedures is highlighted. IntroductionBrunswick Mining and Smelting Corporation Ltd., operates a 10 500 tonnes per day lead /zinc/copper I silver underground mine some seventeen miles southwest of Bathurst, New Brunswick .The No. 12 orebody, first discovered in 1952 by a group headed by M.J. Boylen, had extensive development, including two shallow shafts (500 ft), and test work carried out on it by St. Joe Lead between 1953-1957. However due to complex metallurgy and depressed metal prices, the operation was suspended.In 1961, a group comprised of M.J . Boylen, K.C . Irving and Patino acquired the rights of St. Joe Lead to the No. 12 property. A concerted development plan was initiated along with construction of the necessary sur face facilities and by July 1964, the property was in production at 4500 tons per day.In 1967 Noranda Mines Ltd. acquired operating control of Brunswick Mining and Smelting Corporation Ltd."

Jan 1, 1988

By Raja V. Ramani

The recognition that surface mining need not be viewed as a permanent dedication of the land but rather as a temporary non-renewable use in a series of land uses has caused greater emphasis on the re-use of surface-mined lands. In an effort to develop a procedure for evaluating postmining land use potentials, specific mines in various regions of the U.S. have been studied to determine the extent of current mined-land planning and to discover characteristics that are regional in nature. As part of this investigation, the Indian Head Mine, which is located in Mercer County, North Dakota, has been studied. The Indian Head Mine is presently operated by The North American Coal Corporation -Western Division and has been in operation since 1917 under various ownership. The status of current reclamation and postmining land use planning was reviewed. In addition, the relationship between mine planning and public planning in an area impacted by energy development was investigated. Finally, key factors affecting site potential realization for western surface mines have been identified.

Jan 1, 1983

By V. V. Nazimko

Abandoned coal mines cause subsidence and structural damages. Shallow abandoned mines induce the most severe and harmful damages. In addition, they produce time-dependent subsidence which is difficult to predict. Backfilling of underground cavities with waste materials have been used to prevent the time-dependent subsidence or to mitigate its effect. However, this procedure is expensive. A new drill and blast technique has recently been proposed to prevent surface damage from time¬dependent subsidence over abandoned mines. It utilizes the principle that blasting in the caved rock and roof in the vicinity of a cavity will dilate the ground and create a self-supporting effect owing to increase in the volume. Physical modeling has demonstrated that artificial dilation of caved rock using the drill & blast technique creates positive effects due to the following sequence of events: the dilated rock creates a supporting effect for the suspended rock strata and reduces its span which decelerates 3.4 times the process of caving. The roof span is reduced by the next caved layer, which causes the hole boundaries to incline to each other. This effect converts the process of caving from a developing mode to a reduction mode. Finally, the sinkhole zone assumes a triangular shape with a negative angle of draw 64-700 in contrast to a rectangular shape of the chimney zone for natural caving. Vertical dimension of the triangular zone is 3.87 times of the room height. Final surface subsidence decreases at least 2.09 times; displacement 1.31 times, slope 2 27 times; curvature 3.42 times, horizontal strain 1 21 times in comparison to natural caving of the ground over an abandoned mine.

Jan 1, 1999

By M. K. Larson

Proper employment of numerical stress analysis design tools is based on the demonstrated ability of a model to capture key elements of the geologic site model and accurately simulate how these elements interact with a mine design. While these tools have progressed markedly, they are, at heart, a gross simplification of the abundant complexity of a natural setting and its response to mining. A generic deep longwall site model was developed that includes aspects of the geology of deep coal mines in the Wasatch Plateau and Book Cliffs coal fields of Utah. The site model contains a set of common features and observations of how these features typically respond to mining. This site model was the basis for evaluating use of empirical, boundary element and volume element stress analysis tools to analyze the distribution of stress around a deep longwall panel. More specifically, this evaluation examined shifting of stress to panel abutments and gob, distribution of stress in the abutment, and deformation and failure of bridging strata. Measurements of abutment stress changes at two sites in the Wasatch Plateau region were used to illustrate model calibration. Overall, these comparisons highlight the considerable differences between methods. Volume element tools can incorporate considerable detail and have fewer underlying assumptions, but this detail carries a considerable computational cost. Boundary element tools are much more efficient. But this efficiency also comes at a cost of added assumptions. These assumptions were challenged by the presence of a strong sandstone unit in the overburden, leading to boundary element results that depart significantly from volume element results. Empirical rules are the simplest, but are even more burdened by assumptions, many of which are implicit in underlying cases. Insight into the nature and impacts of underlying assumptions in each method is essential to proper use of results in mine design. Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health

Jan 1, 2009

By R. J. Burgess

During World War II the shortage of ore revived interest in eastern iron deposits, among which -!2..c "Ile Massachusetts and Connecticut limonites. The Cheever mine, in the Richmond-Salisbury area of Massachusetts, was formerly a large producer of limonite ere. The Bureau of Mines investigated the lateral and downward extensions of the Cheever ore body, which was mined from about 1850 to 1892, by ap open cut 1,000 feet long and also by underground workings. even holes aggregating 1,723 feet, were drilled by the Bureau during the winter of 1943-44. They comprised three diamond-core drill holes, two churn-drill holes, and two rotary-drill holes. A geophysical survey of the Cheever mine area and adjoining ground was made in conjunction with the drilling program. Although this survey did not locate the limonite ore beds, the data were of considerable assistance in locating the limestone contact which forms the footwall of the ore beds. Drilling disclosed two beds of limonite with a heavy overburden of glacial till.

Jan 1, 1949

By William E. Greenawalt

IN these days of special legislation for the benefit of various industries one might well consider one branch of human endeavor intimately associated with engineering-that of patents and patent litigation. It is estimated that 85 per cent of all industries in the United States are based directly or indirectly on patents. Most inventors are engineers, and most patent litigation pertains to the engineering industries. It is fitting, therefore, that engineers should be vitally interested in discussing patent affairs, particularly as inventors are not a professional group, and invention is mostly a transitory phase incident to the development of specific industrial problems.

Jan 1, 1937

By G. H. Bennett

A field experiment was performed in a production unit of an operating copper room and pillar mine to compare the support capabilities provided by resin and mechanical roof bolts. Resin and mechanical roof bolts were alternately installed in eight intersections in a single entry. Rock mechanics instrumentation was installed to measure roof sag, bed separation, convergence, bolt pullout, torque, and strain. Bolt cost and installation time are included. Two analyses of the test were made. The analysis of the rock mechanics data showed there was no definite difference between the two bolting systems. From a broader analysis on a mine-wide basis it was concluded that resin bolts gave better support. A critical view of the experiment is given in the appendix.

Jan 1, 1974

Thirty mixed cultures of microorganisms from soil, water and mineral samples from the Groote Eylandt Mining Company mine site were approximately three times more effective in biodegrading manganese dioxide (34± 18 mg Mn++/1/day) than sixteen purified strains (11 ± 10 mg Mn++/1/day) isolated from the primary enrichment cultures. Two pure bacterial genera identified as a Pseudomonad and a Bacillus, with an excess MnOz and nutrient, were able to dissolve 106 mg Mn++/litre/day in mixed culture compared with 29 mg Mn++/litre/day when grown separately.

Jan 1, 1983

By Joan Weinberg

Seasonally adjusted new factory orders for primary metals declined in January, February, and March, especially in the steel industry. The decline was part of an apparent slowdown for the entire manufacturing sector. Orders for all durable goods, including not only primary metals, but also clay, glass, and stone products, fabricated metal products, machinery, and transportation equipment, fell in January and February. In March, orders rose a slight 0.8%. According to the U.S. Department of Commerce, the downturns in durable goods orders in January and February were the first back-to-back declines in 3 years. They were largely attributed to a drop in orders for transportation equipment, mainly auto-mobiles and aircraft, while the small gain in March was due to a surge in aircraft orders. Higher interest rates may be partly responsible for the slowdown in durable goods orders over the past 3 months. The higher rates have also hit the construction industry--another major end-user of minerals. Construction of new homes and apartments fell by a seasonally adjusted annual rate of 5.4% in March, following a 12% decline in February.

Jan 1, 1989

By O. H. Metzger

This is one of a series of papers on placer mining in the western United States. The author has endeavored to give a general outline of the available placer deposits in Boise County, Idaho, together with a description of current practices and the recovery costs of the principal producers. The paper is based on a field examination by the author in May and June 1937. Boise County (fig. 1) is in the southwestern part of Idaho. It has a maximum length of 60 miles, a maximum width of 42 miles, and an area of approximately 1,600 square miles.

Jan 1, 1938

By G. H. Glos

There was a time when an occasional failure of a tailings embankment was considered an acceptable risk associated with mining activities. This is not the case anymore. A major tailings failure today could result in the indictment of mine officials, huge fines and a possible site closure due to the loss of operating permits. As a result of this changed operational environment, tailings disposal facilities must be operated with these potential consequences in mind. Physical controls for tailings embankments are prohibitively expensive. However, the nuclear industry has developed a system of administrative controls as an alternative to physical controls. Administrative controls may be defined as control of actions, through organizations and management, using written procedures, record keeping, review and audit to assure operation of a facility in a safe manner (10 CFR 50). Administrative controls can reduce the cost of operating tailings impoundments, as well as increase the level of confidence in these facilities.

Jan 1, 1999

By B. S. Crocker

Pebble grinding was used at Lake Shore Mines in 1949. A full description of experimental evidence and test plant results was published in 1952 1 and further operating details in 1954 2.' In more recent years the term autogenous grinding has been coined and is now frequently seen in the technical literature. Autogenous crushing and/or grinding covers any grinding mill in which the larger pieces of ore are made to grind the fine pieces; the crushing and grinding may be either dry or wet. This discussion deals only with wet autogenous grinding, and only in the fine grinding part of the circuit, i.e., from 6 mesh to 92 pct —325 mesh. The term pebble milling could apply to fine autogenous grinding in which the pebbles are made from the ore itself, or it could also refer to grinding with pebbles, such as flint pebbles, from a source outside the mine. The first mill to use screened ore to grind the ore (1949) was Lake Shore Mines, Kirkland Lake, Ont. Pebbles were screened from the jaw crusher discharge and used in 5x16-ft tube mills which had been converted to 6 ft 8 in. by 16-ft grate discharge pebble mills. The same general practice was adopted the following year by the Wright-Har-greaves Mine in Kirkland Lake. Shortly after that the Neptune Mines in Nicaragua started correspondence with the writer concerning the possibility of using screened ore for grinding in their plant. They first ran some plant-scale tests which confirmed the Lake Shore findings, with the ultimate result that their plant was successfully converted in 1956 to an autogenous grinding plant. In 1957-1958 the writer was successful in converting the grinding plant of Renabie Mines in northern Ontario to autogenous grinding. In all these plants the existing grinding equipment was converted, usually by expanding the diameter of the shell to make the change from steel grinding to ore pebble grinding mills. In all the above plants primary grinding was done in either small rod mills or ball mills. These mills first reduced the pebble mill feed to about 6 mesh. The final grinding in the pebble mills varied from 75 pct —200 mesh to 92 pct —325 mesh. At Lake Shore three stages of pebble milling were used, with a different size pebble in each stage. In other parts of the world interest was being shown in this form of grinding, and in March 1952 the writer had some correspondence with the mill staff at Outokumpu in Finland, with regard to the pebble system used at Lake Shore. At Stockholm in 1957 the account of the crushing and grinding system at Outokumpu was presented in a paper by H. Tanner and T. Heikkinen.V his is the only ore grinding plant that does not use grate discharges on its pebble mills; trunnion discharges equipped with heavy reverse spirals retain the pebble load. The first new mill designed to use screened ore as a grinding medium was the Bicroft mill at Bancroft, Ont., which began operation in the fall of 1956. In 1957 this plant was followed by similar installations at Faraday Mines, also in the Bancroft area, and the North Rankin Nickel Mines in the North West Territories. In 1958 the Dyno Mill at Bancroft was converted, using the same type of grinding. Since all these plants, designed by Kilborn Engineering (1954) Ltd., were originally planned as pebble grinding mills, they were able to take full advantage of the latest design and technique. They are neat in appearance and very efficient and easy to operate. Effect of Ore Hardness: It is often commented that this type of autogenous grinding applies only to hard siliceous ores. Experience has shown that this is not so. In the past ten years the author has had an opportunity to test more than a dozen ores, several of which were quite soft. One of these was shale. The softer ores actually make better looking pebbles than the hard ores. These soft ores produced no particles in the intermediate size range which could not be ground by the largest pebbles in the mill charge. Slabby ores, such as shales, make a suitable pebble for the —6 mesh grinding. It is not generally recognized that for fine grinding a spherical medium is not essential or more efficient. Another frequent objection to pebble grinding is the belief held by some operators that there is too much variation in the hardness of their particular ore to make it acceptable as a source of pebble media. Experience has also shown that this is not a serious problem at all. The variation in pebble load due to changes in the ore hardness is nothing like as great as most people would expect, and the method used for feeding the ore and controlling the the load in the mills is more than sufficient to take care of daily variations in ore hardness. This point

Jan 1, 1960

By K. Wangerud, B. S. Caruso

A water balance model with deterministic and stochastic components was developed and used for the Gilt Edge Mine Superfund Site, South Dakota, to evaluate risks of contaminated runoff discharging to surface waters based on assumed water treatment plant (WTP) rates for different remedial alternatives. The objectives of the modeling were to use a stochastic approach for analysis of precipitation based on historic records, and for probabilistic estimation of annual and monthly runoff from primary disturbed/mining activity areas that currently requires, or will need, treatment at the WTP, water storage and changes in a major pit, and risk of contaminated water bypass of the WTP to a downstream drainage. Subareas/source areas generating contaminated runoff requiring treatment were delineated. A simple water balance model was used based on precipitation inputs and evapotranspiration and groundwater losses. Annual and monthly precipitation records for Lead, South Dakota were used to estimate precipitation at the mine site. A lognormal distribution was estimated for monthly precipitation. The stochastic software package/Excel add-in “@Risk” was used to generate random monthly precipitation values using a Monte Carlo method based on the distributions. The average annual and monthly distribution of pan and lake evaporation, and groundwater losses were also estimated for the site. Stochastic outputs from the model for the end of each month and year included contaminated runoff requiring treatment, water storage in mine pits and the risk of WTP bypass given different assumed WTP rates. The probability of the time required to dewater the pits was also modeled.

Jan 1, 2002

By Jonathan Ludlow

This document is the final report of a study aimed at defining the relative contributions of various sources of respirable airborne dust on longwall faces. In order to define the contribution of various primary sources, continuous dust level data were recorded on five longwalls for an average of five shifts at each. By analysis of these data with records of face activity, it was possible to determine the overall contribution of each of the major elements of the longwall system to overall respirable dust exposure at various face locations. Average levels were determined for roof support generated dust, conveyor and intake dust and for dust levels during various shearer activities. When average levels are compared between mines, a significant degree of consistency is noted. The next phase of the study was aimed at differentiating the various dust sources associated with the shearer. To this end 'fly cuts' varying from 6 in. to 30 in. were closely monitored as were dust levels at operators' positions over the various segments of longwall cycle. These data indicated that the clearance ring of the shearer drum as a disproportionately heavy contributor to shearer dust make. A statistical analysis of the effect of shearer haulage speed on dust make revealed that high haulage speeds are associated with low specific dust make.

Jan 1, 1983

By William O. Vanderburg

This report 3/gives the results of a reconnaissance of the mining districts in Lander County, Nev., made from March 29 to April 20 and from May 9 to May 21, 1938, during which virtually all of the mining districts n the county were visited. No attempt has been made to include in this report all the mines and prospects in the various mining districts, and it should be stated that whether or not a property is mentioned herein has no. bearing on its merits. The report rovers the situation of the various districts, types of ore deposits, ownership and description of mines and prospects, information on past and current activity, and other information of economic interest likely to be useful to those interested in the development of our mineral resources. The names of the various districts mentioned are those generally used when they were organized for purposes of record and regulation. When originally organized, the districts embraced large areas with no well-defined boundaries, so that the names have little geographical significance.

Jan 1, 1939

By R. C. D. Phillis

The annual mine planning process is one of the most important tactical/operational steps towards achieving strategic goals. These tactical plans are part of a very comprehensive Mineral Resource Management process, with the natural sequel to planning being execution. The execution of an underground hard rock mine plan is a multi-project environment that comprises many development-construction-equipping-stoping single project paths, which are referred to as ?stoping paths?. The uncertainty that typifies execution of projects comes in the form of untimely disruptions to constituent tasks and/or project paths. Annual mining plans also include quantified objectives for occupational health and safety, production, quality, cost, employee morale, environment, and corporate social investment. Such objectives make for a highly complex environment that management must contend with?complex in the sense that all the paths and objectives have interdependent constraints. Furthermore, at the time of this paper, Sections54*and 55**of the MHSA*** put the onus on management to ensure legislative adherence. It stands to reason that planning estimates allow excess capacity?buffers?that cushions the impact of untimely disruptions. This paper concerns the fact that despite all the buffers allowed for, time, scope, and budget creeps impact on mine planning and threaten its successful execution. As a consequence, the paper deals with buffer management, the essence of Critical Chain Project Management (CCPM). Effective buffer management provided strategic (executive level) updates without losing the tactical/operational detail necessary for job card creation, especially where professional skills and experience are in short supply. Indicative bottom-line results showed CCPM to be highly effective.

Jan 1, 2011

By G. Song

"SynopsisAccording to the overlying rock strength and thickness of 10 shallow coal seams in China, the strata are classified into four types: weak and laminated strata (hereinafter referred to as WL), weak and massive strata (WM), strong and laminated strata (SL), and strong and massive strata (SM). The four types of strata, together with longwall panel height (M), panel length (L), and seam depth (H) are factors that influence the loads on hydraulic power supports. Principal component analysis was used to study the seven influencing factors. It turns out that seam depth (H) is multicollinear with WL, WM, SL, and SM. Thus the enumerated seven factors are divided into two models. In Model 1, six factors; panel height, panel length, and layer thickness of the four type strata are involved. In Model 2, three factors; panel height, panel length, and seam depth are included. Using multivariate regression analysis, two equations to calculate loads on supports are obtained for each model. The equations were applied to shallow coal seams. The equation of Model 1 is more accurate than that of Model 2, but Model 2 could be further used in deep coal seams. The equations were coded through VB programming to simplify the calculation.IntroductionTo ensure coal production in the long term, the focus of coal mining has been gradually shifted to the western areas of China in recent years due to rich coal resources in this region. Most of the coal seams in this area are shallow but the support loads are abnormally high. In these circumstances, the chock loads estimating methods used in the past do not work. If the rated working resistance of a support is larger than needed, the shield is unable to fully perform, while a lower working resistance would lead to accidents like shield crushing or even casualties. This problem is frequently found in shallow coal seams such as Shenfu-Dongsheng, Yulin, Tuha, Lingwu etc. (Zhang, 2011). Thus, to ensure safety and efficiency during mining, the estimation of support loads and selection of supports are of great significance."

Jan 1, 2015

By Michael W. Neill, O&apos

Drilling slurry has become an effective aid to the construction of drilled shafts in caving and/or waterbearing soils. Historically, drilling slurry made of bentonitic clay and water was first used in the US in water well drilling as early as 1889. In coastal Texas drilled shaft contractors began using slurry, often made of on-site clay mixed with potable water, in the years following World War II, on a relatively routine basis. This type of slurry was used to "process" boreholes, in which the borehole was drilled "in the dry" until water or unstable soil was encountered, after which water and on-site clay were introduced into the borehole and mixed in place with the auger or other drilling tool. Drilling then continued under a slurry consisting of the uncontrolled mixture of clay and water until the excavation had reached a relatively impermeable and cohesive material. At this point, a steel casing was dropped into the hole and sealed into the lower stratum of impermeable geomaterial (soil or rock). The slurry inside the casing was bailed or pumped out, drilling continued to plan depth in the dry, a reinforcing cage was set in the partially cased borehole, concrete was placed and the casing was withdrawn. Some soil-slurry was undoubtedly trapped between the casing and the borehole wall, but the quality of that slurry was usually of no concern, because engineers of the period usually viewed drilled shafts as nothing more than deeply buried footings. Any unejected slurry would only serve to lower side shearing resistance, not yet considered in design, but would have no effect on end bearing. In the 1960 's the effectiveness of soil-slurry came into question because it was often ineffective in maintaining borehole stability at marginal drilling sites and because the economy of using shaft resistance, in addition to end

Jan 1, 1991