Search Documents

By R. G. Meara, O&apos

The land-pebble district of Florida, which in 1928 supplied 96.7 per cent of the phosphate production of that State and 82 per cent of the domestic requirements of the United States, is centered in Polk and Hillsboro Counties about 30 miles east of Tampa The deposits are unconsolidated sediments occurring as beds of phosphate matrix overlain by a mantle of barren sands and clays. The matrix consists of a mixture of Sand (quartz grains), clay, and phosphate rock in which the coarsest sand is much finer than the coarsest phosphate; that is, the sand is segregated in the fine material. Before the introduction of classifiers the concentration consisted of log washing, and screening at about 20-mesh, which was usually the finest size that could be taken to maintain commercial grade, 66 per cent B. P. L. (bone phosphate of limey or more. When classifiers were introduced some of the fines that had escaped at the head of the washery and some of the minus 20-mesh material isolated during the rushing and formerly lost supplied the feed.

Jan 1, 1931

By Stephen R. Iverson

Mineral deposits examined in and near the Raywood Flats RARE II area have low potential for development. The Mill Creek Mine (fig. 1), has produced about 14,000 tons (13,000 t) of marble, and another 5.5 million tons (5.0 million t) of marginal marble reserves suitable for lime, chemicals, and cement production are estimated to remain at this deposit. However, nearly all the marble is outside the study area. The deposit is marginal because alternate sources of marble are closer to markets. A tungsten occurrence in the marble is too small and low grade to be considered a resource. Ten tons (9.1 t) of uranium- and thorium-bearing material have been mined from a pegmatite dike at the St. Patrick Mine. However, this occurrence also is too small and low grade to be considered a resource. More than 400 lode and placer claims have been located in or near the study area. There are no current claims or mineral, oil and gas or geothermal leases.

Jan 1, 1983

By Ralph P. Carter

It is apparent that coal will play an increasingly important role in satisfying the nation's energy requirements for the remainder of this century. Both deep mining and surface mining will be practiced to develop known U.S. coal reserves, but until significant improvements in the productivity of deep mining emerge, surface mining is likely to be predominant. This report addresses the problems of coal extraction and surface mine reclamation in the 11-state Midwestern coal resource region, where surface stripping of high-sulfur, bituminous coal has been a well-developed industry for most of this century. Midwestern coal markets have declined in recent years. In part this is a result of widespread conversions to more convenient and (apparently) economical liquid and gaseous fuels, but the decline in Midwestern coal use is also attributable to the impact of current air pollution control regulations that prohibit emissions of sulfur oxides and particulate matter. A part of the regional demand for Midwestern coal has been transferred to the Northern Great Plains where extensive low-sulfur coal reserves are currently being developed.

Jan 1, 1974

This report is the 23d in a series summarizing research and technologic work by the Federal Bureau of Mines on coal and related investigations; it is the fifth report to be issued on a calendar-year basis.2/ Publications by Bureau personnel in 1958 are cited;3/ in addition work in progress during the year is briefly described. To conserve our reserves of coal the Bureau of Mines conducts a program concerned with the development of fundamental information on coal characteristics and behavior, and the improvement of technology related to its production and utilization. The ability to anticipate and meet future demands for coal depends on a number of factors: (1) Knowledge of reserves from a stand- point of both quantity and quality; (2) the development of improved mining methods, health and safety measures, and preparation techniques that will insure its most efficient exploitation; and (3) knowledge of the controlling factors in efficient use of coal in combustion, carbonization, gasification, direct and indirect hydrogenation, and other new processes. The Bureau is concerned with each of these areas.4/,5/

Jan 1, 1960

By L. C. IlsLey

Figure 1 is a reproduction of a chart recently prepared by the Bureau of Mines at its Pittsburgh Laboratory to show the Bureau's approval work in connection with electrically operated mining equipment. Nearly 27 years of approval work, covering 346 approved units, are shown on this chart. These approvals are arranged according to year of approval and the manufacturer to whom approval was granted. Forty-five manufacturers are represented, and a scheme of using various colored tabs permits the following subdivision of the equipment: Cutting machines, loading machines, conveyors, battery-operated locomotives, battery-operated power trucks, drills and drilling machines, rock-lusting machines, pumps, room hoists, air compressors,, and miscellaneous, The greatest number of approvals granted to a single manufacturer is 80; the next highest is 65, and the third is 49. Several manufacturers have been granted only a single approval. The chart shows all approvals granted for, motored equipment. Some of these units have since become obsolete, and a few are used to a very limited, extent if at all.

Jan 1, 1941

By Stephen C. Tadolini, Yunqing Zhang, Thomas M. Barczak

Standing crib supports have been applied in underground mining programs to resist large roof movements and sustain high-loads. The strength and deformation capability of these systems has been documented under both laboratory and field conditions. The parameter that has not been examined and is not well understood is the effect that a crib or other types of standing support has on the primary and secondary bolting systems. A crib support system with low system stiffness may allow large amounts of closure and deformation and cause the bolting systems to yield or even fail. Conversely, cribs or standing support that are too stiff may experience brittle or buckling failures, negating the advantage of the intrinsic supports previously installed. Utilizing a combination of field measurements and 3-dimensional finite element modeling techniques, the relationship between system stiffness and the subsequent performance of the installed bolting system is evaluated. Additionally, a simple method for calculating the combined system stiffness for standing supports, when using materials with different strengths such as steel, concrete, wood, etc., is presented.

By E. P. Youngman

The mining laws of Russia (Collection of Laws, vol. 7, 1912) are still in force in Latvia. The Free State of Latvia (declared independent on November 8, 1918) is composed chiefly of the Baltic Provinces of the former Russian Empire, which are ethnographically Lettish: The Province of Courland, four districts of the Province of Livonia, and three districts of the Province of Vitebsk. Since the establishment of its independence, Latvia has not felt the need of a special mining law, inasmuch as mining so far has not been found profitable in that country. A supplement to this paper, entitled "Mineral Resources," is a brief summary of the minerals found and utilized in latvia. RIGHTS OF FOREIGNERS A foreign individual is permitted to explore for minerals and to own and operate mines in Latvia on equal terms with Latvians. A foreign corporation is required to establish a branch in Latvia, which shall be subject to the corporation laws of the country. A certain number of the partners or incorporators must be citizens of Latvia.

Nov 1, 1931

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

C. 4 Hoist Assemblies (not man-rated) A large number of manufacturers supply materials handling winches. These units are predominately electric powered while a limited number of vendors supply air powered equipment. Air powered units are currently used extensively for underground materials handling purposes. Suppliers of materials handling equipment normally include a disclaimer statement in their published literature which clearly states that the equipment "is not designed or suitable for lifting or lowering persons " This category of commercially available equipment can be adequate for emergency man hoisting provided that its' capacity is suitably derated and provided also that the necessary safety features are incorporated. Section C. 5 details the equipment which could be added to a commercial materials hoist to meet these needs. Four commercially available hoist assemblies, two electric and two pneumatic are discussed in the following paragraphs. This equipment is typical of what is commercially available and three of the units are currently used extensively in mining applications. Each hoist description includes a remarks paragraph which identifies the additional equipment each hoist would require for emergency hoist use.

Jan 1, 1976

By Howard E. Parkinson

A brief description is given of various Bureau of Mines research activities that have begun since July 1974 and are not being reported on by others at the Third West Virginia University (WVU) Conference on Coal Mine Electrotechnology. An essential feature of the various projects is that they are pragmatic. The projects are applied research and are carried out both by the Bureau in-house research group and by other research groups through contract research. Projects have been directed toward wired-type communications with a special effort to modify the wired systems so as to be more effectively used. The projects are in three groups: Pager phone systems, trolley line phone systems, and guided-wire wireless communications. Also, a brief sketch is given of research that is essential for further developments in mine communications. From the early results of these various projects, the Bureau has good reason to project that there will be improved performance of existing communication systems and that communications will be extended to other individuals working in areas that are excluded from present mine communication systems.

By P. Yant, A. C. Fieldner

"IntroductionIn its investigations relative to reducing the hazards of carbon monoxide poisoning, the Bureau of Mines recently had its attention drawn to a compound2a sold under a trade name for which claims are reported to have been made regarding its efficacy in reducing that type of poisoning in automobile garages. Accordingly, some of the product was obtained and analyzed for its power to absorb, oxidize, or destroy carbon monoxide; and the results are herein reported.Description of ""Compound"" (quoted from manufacturer's circular)While the circular does not actually state that the ""compound"" protects against carbon monoxide, the inference is therein, because each of the two following quotations is below these respective headings; ""Carbon-Monoxide Poisoning,"" and ""Chronic Gassing Among Garage Workers.""The ""compound"" holds chlorine and oxygen gases in solution with formaldehyde, which unites with the hydrogen to form hydrochloric acid., giving an over-supply of oxygen which burns up carbon just as a piece of wood is burned in the fire. The formaldehyde in the composition of the ""compound"" is a great affinity for ammonia and hydrogen sulphide."

Apr 1, 1924

By Thomas J. Peters

In 1988, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied the 34,310-acre Diablo Mountain (Additional) study area (OR-001-058), in order to evaluate its identified mineral resources and occurrences. The study area lies along the east shore of saline Summer Lake in Lake County, OR, about 145 miles southeast of Bend and 45 miles northwest of Lakeview. The climate is semiarid and temperate, and the study area is almost treeless. Geologically, the (Additional) study area is in a region of fault block-formed mountains and basins, characterized by interior drainage. The area is mainly underlain by unconsolidated Quaternary and Pleistocene lake and playa sediments, which may include subsurface evaporite mineral deposits and resources. Near the center of the eastern margin of the study area are an occurrence of dolomitic limestone of unknown extent, and an area of basalt outcrop totaling 1.5 square miles. A veneer of windblown sand covers about one-half the study area.

Jan 1, 1989

By Norwood B. Melcher

This report describes preliminary experiments by the Federal Bureau of Mines on the practicability of adding raw pellets of taconite concentrate to blast furnace feeds. The usual industrial practice is to harden the pellets by heating before they are charged to the furnace. The Bureau research demonstrated that raw pellets could be successfully smelted in an experimental furnace with no significant change in coke consumption and only a moderate increase in dust losses. The dust loss was 43 pounds per ton of metal for an all-pellet charge, compared with 7 pounds per ton for an all-sinter charge. Raw taconite pellets undergo only slight degradation during charging to the furnace if 1 percent bentonite is used as a binder. INTRODUCTION Fines and concentrates must be consolidated or agglomerated into larger masses before they can be smelted in a commercial blast furnace. Such agglomeration is usually done by sintering, pelletizing, nodulizing, or briquetting. Sintering has been the more common practice, but with the advent of taconite concentrates pelletizing is increasing in importance.

Jan 1, 1960

By R. A. Beall

A series of 45 zirconium ingots has been cast by the consumable electrode arc melting process with the object of analyzing the effects of power input from 50 to 230 kilowatts and reduced pressure furnace atmosphere to improve the quality of regular 8-inch-diameter production ingots made thereby. Electrode consumption rate, molten pool volume, melting efficiency, sidewall quality, arc stability, and yield efficiency are considered. The use of direct current and alternating current is studied. In conclusion, reduced pressure furnace operation is shown to promote electrical efficiency, ingot homogeneity, high metal yield, and are stability. INTRODUCTION Zirconium is a particularly difficult metal to melt because of its affinity for atmospheric gases and its solvent properties when molten. In addition, zirconium sponge as produced by the boll process contains minor amounts of magnesium chloride, which cause severe spattering luring melting, because of these difficulties with zirconium, and its sister metal titanium, near techniques have been developed to permit production of commercial size ingots. Among the more promising is the consumable electrode arc melting method.

Jan 1, 1955

By N. E. Hanna

The effect of small percentages of sodium chloride on the incendivity of permissible explosives was studied by the Bruceton up-and-down technique in gallery tests. Both the reduction in incendivity achieved by addition of sodium chloride and application of the test method to explosives evaluation are discussed. It is demonstrated that the up-and-down technique in gallery testing is suitable for distinguishing differences in incendivity between different explosive compositions and between lots of the same composition. The study also shows that addition of relatively small quantities of sodium chloride tends to reduce the incendivity of explosives to firedamp, but addition of sodium chloride cannot insure reduced incendivity. Any improvement attributable to the salt can be counteracted by undefined variations in the explosive. The need for experimental investigations of a number of factors that may affect the safety of permissible explosives is emphasized. ACKNOWLEDGMENTS Grateful acknowledgment is made of the assistance of Roy L. Grant in analyzing for normality of distribution of the data obtained by the up-and-down methods and to Harold E. Tubbs for numerous calculations.

Jan 1, 1959

By S. Gallagher

If we consider ergonomics to be an exercise in matching job demands to worker capabilities, one of the principal capabilities we must be concerned with is that of human strength. Our ability to evaluate different characteristics of muscular strength has increased dramatically over the past couple of decades with the development of new and increasingly sophisticated instrumentation. One would think that armed with such advanced techniques, we might be able to develop methods to conclusively identify workers at risk of injury in physically demanding jobs. Unfortunately, this has not yet proven to be the case. Instead, what these instruments have continued to point out is how intricate a function muscular strength really is, and how complicated and ambiguous its relationship is to musculoskeletal injury. While we cannot just use isolated tests of strength to specify precisely who may be at risk of injury, studies have indicated that strength testing can be a useful tool for job design and, under certain circumstances, selection of workers for demanding jobs. However, because strength is such a complex phenomenon, there has often been some confusion regarding the proper application and interpretation of strength tests in ergonomics, especially among persons not thoroughly familiar with the limitations and caveats associated with the available procedures. The purpose of this chapter is to discuss some of the fundamental principles of strength assessment in ergonomics, so that these procedures can be better applied to control the risk of musculoskeletal disorders in the workplace 1.1. What is Strength? (And what are we Measuring?) Many of the complications associated with strength assessment arise from the simple fact that even our most sophisticated machinery does not directly measure the force or tension developed by a muscle in a living person. Instead, we can only observe the consequences of force development by a contracting muscle, or more likely, by a combination of muscles There are many ways in which we can measure the effects of muscular contraction, and the techniques we use can have a dramatic impact on the strength readings we will obtain. Consider the situation illustrated in Figure 1. In this example, the muscle exerts a constant force of 1000 Newtons (N). However, the forces we measure can vary quite dramatically depending on where we place the force cuff - from 167 N if we place it near the wrist to 500 N if we place it near the elbow. Which value should we select as properly representing the muscular strength for this elbow flexion exertion? The preceding example illustrates some important points with regard to strength assessment. Perhaps the most important is that "muscular strength is what is measured by an instrument" (Kroemer et al. 1999). It should also be clear from this example [ ] that two researchers could perform an elbow flexion strength experiqent on the same group of subjects, but if each selected different force cuff positions, they might end up with wildly differing estimates of strength. Differences in the strengths of various muscle groups in the published literature may be the results of differences in the procedures and measurement methods used by the experimenters Thus, it is critical that any strength data presented be accompanied by a detailed account of the manner in which the data were obtained. A few additional points need to be made with regard to the testing of human strength. We must be clear that what we are obtaining in such tests are not a person's maximal strength capability, but their maximal voluntary strength. The voluntary nature of the exertion introduces an unknown, but surely substantial, amount of variability in our measurements of strength. One can imagine two subjects with identical muscular strength capabilities, but with varying levels of motivation or discomfort tolerance, for example. We are likely to observe considerable differences in the voluntary force exerted by the two, but it should be understood that such results may be largely the result of psychological factors, and not differences m muscular strength per se. The important point to be made here is that not only are we unable to directly measure muscular force, what we are able to measure is modified by an invisible filter - a filter subject to a wide variety of influences and which will differ considerably for every person we test To make matters worse, this filter would be expected to change even within a given individual on a given day. From the foregoing discussion, one can perhaps better appreciate some of the difficulties with establishing a definitive relationship between an individual's measured strength and that individual's risk of injury.

By John J. Sammarco

Abstract- Emergency shutdown systems (ESDs) for mining machinery provide critical functions to safeguard miners. Traditionally, ESDs were realized with simple hardwired circuits; today, there is a growing trend to use programmable electronic technology such as programmable logic controllers (PLCs). This paper describes an analytical study to quantify the safety integrity of a PLC-based ESD and a hardwired ESD. The safety integrity level of each design approach was determined by quantifying the average probability of failure on demand (PFDavg) as described by the recommendations for programmable electronic mining systems published by NIOSH and the IEC 61508 international standard. The safety analyses addressed system architecture, hardware failure probability, proof test interval, diagnostic coverage, and human error probability. The results indicated that a same level of safety, safety integrity level 3 (SIL 3), could be attained when evaluating random hardware failures. Neither approach could attain SIL 3 if manual activation was used. Human error was the limiting factor where, using human reliability analysis, PFDavg < 1 x 10-1; thus, the ESD does not meet SIL 1. It is apparent that automatic verses human¬activation of the ESD is a very important safety consideration. Manually actuated ESDs can only achieve SIL 1 regardless of the technology; therefore, additional independent safety layers of protection are needed to exceed SIL 1. Secondly, it is apparent that the technology choice is very important. The PLC-based ESD was much simpler to design and to validate safety1.

Jan 1, 2007

By Gerrit V. R. Goodman

In This Chapter [Design and operation of machine-mounted scrubbers Dust control with scrubbers and blowing ventilation Dust control with scrubbers and exhaust ventilation Dust control with exhaust ventilation and no scrubber Dust control methods common to all continuous miner sections Dust control for roof bolters] This chapter explains how to control dust at continuous miner sections in coal mines where the main dust sources are continuous miners and roof bolters. In relation to dust, there are three categories of continuous miner faces depending on the type of ventilation and whether or not a machine-mounted dust scrubber is used. These are— 1. Mining machines with dust scrubbers used with blowing face ventilation 2. Mining machines with dust scrubbers used with exhaust face ventilation 3. Mining machines without scrubbers used with exhaust face ventilation The approach to dust control is somewhat different in all three of these. However, there are many dust control features (such as the need to provide adequate airflow) common to all continuous miner sections. For workers at roof bolter faces, there are two dust sources: 1. Dust from the continuous miner when it is upwind. 2. A malfunctioning dust collector on the bolter, which allows dust to escape DESIGN AND OPERATION OF MACHINE-MOUNTED SCRUBBERS [Almost all new continuous miners are equipped with scrubbers. When the dust is excessive, it is possible that the scrubber needs some maintenance.]

Jan 6, 2003

By C. B. Manula, R. L. Sanford, R. A. Rivell

Data input is divided into three divisions for discussion purposes below. These divisions are: a) Information Retrieval and Control Options; b) Gaming Options; and c) Descriptive Parameters. The data input for model application, which is listed in Appendix B, is segmented to show the location of these divisions. In actuality, however, these divisions form a continuous data file. Each 80 character record of data input is edited by an alpha¬numeric editing routine which permits the format free numerical speci¬fication in most data divisions. The editing routine searches each record for numeric types and when found, converts these numbers into computational forms. The Fortran convention of decimal and integer numbers is not used by the editor so that a number may appear on the data record in either form desired by the user. Since the editor seeks only numeric types, the input records may be freely commented and identified with alphabetic letters (A - Z). One or more input records may contain only commentary information or be entirely blank. On the other extreme, any data record may contain up to 40 numeric elements, each separated by a blank space. The application of this capability can be seen by reference to the data. Information Retrieval and Control Options The information retrieval options specify the detail of infor¬mation required to be printed. These have been placed in a separate data division, identified on the data record by option name for use

Jan 1, 1974

By Horace M. Lawrence, Edmund S. Leaver

"The sulphidizing filming of minerals in oxide ores as a preliminary treatment to aid their recovery by flotation is known practice. In this work the use of barium polysulphide does not appear to have been considered. A study of the properties of barium lead to the following comparative investigation of the sulphides and polysulphides of the alkaline and alkaline-earth metals. It is thought that barium polysulphide may prove to be a more satisfactory sulphidizing reagent than others now in use under conditions that favor the cheaper barium reagent.For the investigation two fairly typical oxidized ores of copper and lead were selected. The copper ore came from the Big Indian Mine in southeastern Utah, and assayed 3.8% Cu; the copper was present in a sandstone gangue mainly as the carbonates, malachite and azurite, with less than 0.2% as sulphides, or silicate. The lead ore is from the Tintic Standard mine in the Tintic district, Utah. It is typical of the oxidized lead-silver ores of that district; the lead is present in an oxidised form in a siliceous gangue, much: Uncolored by ferric oxide. The sample assayed 5.15% Pb and 11.3 oz. Ag.In addition to the results obtained in this investigation, there are included some results secured by Mr. J. B. Lain, consulting metallurgist of Reno, Nevada, on a sample of ore from the Chino Copper Co. The ore assayed about 1.7% Cu, of which about 0.25% was nonsuiphide."

Aug 1, 1925

By Nicholas Kyriazi

Significant portions of the present Federal regulations for certification of closed-circuit breathing apparatus (42 CFR 84) are not quantitative. The human-subject testing portion of the regulations specifies activities rather than metabolic work rates; however, heavy human subjects have higher oxygen consumption, CO2 production, and ventilation rates than lighter human subjects performing the same activities. This means that apparatus certified using different human subjects have effectively passed different tests. In addition, apparatus performance is monitored only during selected intervals of testing, and always during rest, rather than during the entire performance period. Further, testing is arbitrarily terminated at specific rated durations, leaving unknown the performance during the remaining duration. Duration itself is misleading to users who believe that the apparatus will last a certain time no matter how much they weigh or how hard they work. The actual duration obtained from an apparatus, however, is highly variable, being inversely proportional to the work rate at which it is used. In this report, recommendations are made to (1) replace the present regulations for certification of closed-circuit breathing apparatus with quantitative tests specifying metabolic work rate rather than activity,(2) continuously monitor relevant physiological stressors, (3) continue testing until exhaustion of the oxygen source, and (4) classify closed-circuit breathing apparatus by quantity of usable oxygen, i.e., capacity, rather than by duration. Physiology-based stressor levels are suggested as well.

Jan 1, 1999