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By Robert H. Dickson

This paper describing the mining practices at the Verde Central mine at Jerome, Ariz., is one of a series being prepared by the United States Bureau of Mines on mining practices, methods and costs in various mining districts of the United States. ACKNOWLEDMENTS The costs contained in this paper were prepared by R. J, Huddleston, chief clerk, Verde Central Mines, Inc.

Jan 1, 1931

By W. J. Long

As a part of the strategic mineral exploration program, examining engineers of the Bureau of Mines collected samples of ore from four manganese properties in Yavapai, Yuma, Maricopa, and Mohave Counties, Ariz. As all of the ores were too low in grade to be acceptable by manufacturers of ferromanganese beneficiation studies were made to determine the amenability of the ores to concentration.

Jan 1, 1948

By M. J. Ankeny, J. J. Forbes

The United States Bureau of Mines often receives inquiries from the mineral , petroleum , and allied industries concerning the essential steps to be taken in the formation of Holmes Safety chapters and councils . The purpose of this circular is to answer in a general way such inquiries and to relate briefly the history and work of the Holmes Safety Association to the present date .

Jul 1, 1931

By H. L. Riley

This report describes the methods and equipment used by the Watauga Stone Co. to drill und blast limestone in a two-level quarry, and to crush, screen, blend, and load this stone. Power requirements per ton of stone produced are reported. The personnel requirements for individual phases of the operation are tabulated in man-hours per ton of stone produced.

Jan 1, 1963

By H. L. Riley

This report describes the methods and equipment used by the Watauga Stone Co. to drill and blast limestone in a two-level quarry, and to crush, screen, blend, and load this stone. Power requirements per ton of stone produced are reported. The personnel requirements for individual phases of the operation are tabulated in man-hours per ton of stone produced.

Jan 1, 1963

By T. T. Read, F. C. Houghten

"The bad effects upon the health and output of miners that result when the ventilating current in a mine lacks sufficient cooling power have been described by Harrington and Sayers in a previous report (1)*** The normal temperature of the human body is about 98.5°F. and whenever work is done by the muscles, indeed even when sitting still, the normal bodily processes generate heat which must be given off, otherwise the body will become overheated and a number of bad effects will be produced. If it were possible to so enclose a man that he could continue to breathe and no heat could escape from his body he would die within a short time. In a series of experiments made at the Pittsburgh Station of the Bureau of McConnell and Houghton (2) found that a dry-bulb and a wet-bulb temperature of 112.5°F could he borne for only 35 minutes, even when the subject was at rest. A wet-bulb temperature of 100.4°F (dry-bulb 157°F) could only be tolerated for 45°F minute. Under such conditions the bodily temperature rises as much as 45°F above normal and the pulse is accelerated. Very uncomfortable sensations are felt when the pulse rate exceeds 135. The human body, like any other internal combustion engine, must be cooled in order to function properly.Under ordinary circumstances the air surroundings people is enough coder than themselves to permit this heat generated within the boiy to be river off with¬out difficulty. At higher temperatures, or when the rate of work, with its corresponding generation of heat is high, the body can not throw off heat fast enough, so it begins to sweat and the evaporation of the sweat cools the body. But the results of the experiments cited above indicate that in still air, even with the body at rent, it can not adjust its temperature when the air is above 90° wet- bulb. J. S. Haldane (4) says ""at a wet-bulb temperature of 60°F the actual amount of work done by the miner begins to fall off; as the wet bulb temperature rinse farther the work Bona gradually diminishes to the vanishing point. Then the temperatures indicated by the wet-bulb exceeds 85°F hard work in a mine seems hardly or the commercial working of a mine the wet-bulb thermometer should not in generaI, be allowed to rise above 80°F, unless perhaps where there it a good current."

Dec 1, 1923

By Leonard Greenburg

The analytical procedure necessary when using this new impinger•bubbler eil)paratus is almost identical with that em:r;,loyed with the Palm0r a:pp8.ratua. As sugar is not employei, the new apparatus por.;sesses the advantage over the eug.r tube method in having vsry low control errors, being, therefore, much simple in laboratory manipulation during analysis.

Aug 1, 1922

The investment involved in any communication system represents a considerable sum. Even though it is desirable that the system work properly each and every time it is called into use, some failures are bound to occur. Most failures, however, and especially those that occur most frequently, are due to poor installation techniques. An extra hour spent at an installation site can save many maintenance trips and many frustrating hours of system troubleshooting. Typical faults likely to cause communication outrage are Pager phone systems Poor splices aggravated by corrosion. Strain relief not provided. Drip loop not provided. Incorrect branch connections. Overloading the circuit. Poor battery connections. Improper wire size or type. Lightning strikes. Improper placement of wire runs. Carrier phones Mounting transceiver near load resistors or other sources of heat. Tracks not electrically bonded. Cable abrasion due to poor mounting location. Disconnected battery. Poor mechanical installation. Each installation should be well planned. After an installation is completed, the technician should ask the question, "What can go wrong with this unit or line?" Remember the adage, "Whatever can go wrong, will." Preventive measures taken during installation will pay off in the long run. 6.2 Pager Phone Installation The pager phones used in many underground coal mines are battery-operated, party-line telephones with provisions for loudspeaker paging. The system is usually two-wire, nonpolarized, and operated by self-contained batteries. Many of the individual units are certified as permissible. 6.2.1 Mounting Pager phones are designed to be mounted on an upright support at the desired location. For convenience, the phone should be mounted 5 feet above the floor where there is no obstruction to using the handset or removing the cabinet front cover for servicing or battery replacement. In low-coal situations, a suitable height for installation should be selected convenient to the normal operator's position at the site selected. About 12 inches of free space on each side of the phone should be provided for cabinet access. The phone should be protected against direct exposure to dripping water and should not be allowed to rest in a puddle of water. The mounting location should be convenient to a work location and have a safe, unobstructed area for a worker to stand and use the phone. The phone must be in a location where the worker will not be in the path of moving vehicles or falling debris. Each telephone is normally well insulated, but it is still good practice to provide an insulating mat or dry planking for the user to stand on.

Jan 1, 1984

Coal miners, especially roof bolter and continuous miner operators, work in a hazardous underground environment where they are often exposed to poor roof conditions. Nearly 500 rock fall injuries are reported each year, and 99% of them are caused by rocks falling from between the roof bolts. These loose rocks that injure miners are usually just a few inches thick, but on average weigh 280 pounds. NIOSH has found that most rock fall injuries can be prevented by installing roof screen during the bolting cycle. Roof screen is a sheet made of steel wires in a grid pattern. When screen is bolted up against the mine roof, it provides far more coverage than any common surface control used in the mines today. Because more mine roof is covered, there is less chance that a rock will fall and injure a miner. The facts about roof screen are shown in the new NIOSH video entitled “Make It Safer With Roof Screen.” Using extensive underground footage, the 7-minute video shows how well screen keeps loose rock from falling in difficult roof conditions. Techniques for installing screen from both outside-controlled and walk-thru roof bolting machines are shown. The video also provides safe handling tips, best practices, and information about machine technology that can greatly improve material handling. Throughout the video, a coal mine safety manager and a shift foreman talk about the tremendous difference that roof screen has made at their mines. An instructional booklet supplements the video with additional information. It presents compelling data from mines that have practically eliminated rock fall injuries with a roof screening program. Other sections of the booklet discuss in greater detail roof screen installation, tips for manual screen handling, a material handling system for roof screen, and use of the personal bolter screen, which can be easily handled by one person. Screen specification and custom ordering are described, including the sizes of screen, grid sizes, reinforcing (indicator) wires, edge cut options, and screen strength. A list of additional sources of information is also provided. Nearly every mine eventually encounters poor roof. Screen is one of the most powerful control techniques available. This new video will help make mine managers aware of screen, and it can help them in developing a roof screen installation program. It also serves as an information source and teaching tool for safety managers and trainers. The video can easily be integrated into new miner training programs or annual refresher training.

Mar 1, 2005

By Miyuki Morioka, Michael J. Griffin

Discomfort, annoyance, or interference with activities due to exposure to vibration is only expected if the vibration exceeds the threshold for the perception of vibration. When there is more than one vibration input to the body (e.g. at the hands, seat and feet), the sensation is first experienced at the location with greatest sensitivity. Knowledge of differences in the thresholds of perception for vibration at the hand, seat, and feet should assist the identification of sources of discomfort caused by vibration. Perception thresholds for vibration have been determined in several studies, but only a few studies have investigated perception thresholds in the horizontal direction for hand-transmitted vibration 1, 6 or whole-body vibration 4-5, and there has been little consideration of perception thresholds for the foot resting on a vibrating surface. This study determines absolute thresholds for the perception of sinusoidal lateral vibration, examining the effect of vibration frequency (8 to 315 Hz for the hand and foot; 2 to 315 Hz for the seat) and the effect of input location (the hand, the seat and the foot). Methods Three groups of twelve males aged between 20 and 29 years participated in the experiment. Subjects in each group attended an experiment to determine perception thresholds for lateral vibration via either a rigid handlebar (30 mm diameter) at the left hand (left hand), or a rigid contoured seat (250 mm x 150 mm), or a footrest at the left foot (30.5 mm x 10.5 mm with 10-degree inclination). For the non-exposed hand (right hand) or foot (right foot), a stationary handle and footrest with the same dimensions as the vibrating handle and footrest were provided so that the same body posture was adopted among the three groups of subjects. An up-down (staircase) algorithm was employed to determine thresholds in conjunction with a three-down one-up rule. A single test stimulus (2.0 seconds) was presented with a cue light illuminated during this period. The task of the subjects was to indicate whether they perceived the vibration stimulus or not. The threshold was calculated from the mean of the last two peaks and the last two troughs, omitting the first two reversals. Results The median absolute thresholds of the 12 subjects determined at each frequency for the hand, seat and foot are shown in Figure 1. A frequency dependence of the threshold contours within the investigated frequency range is evident, with similar shape to the threshold contours

Jan 6, 2006

By Nancy Estrada, Jane Nowell, Cathy Jennings, Debra Yniguez, Carol Lavery, Kristin Harrer

Pilots of the MH-60S helicopter are exposed to continuous whole body vibration (WBV). Pilot fatigue is a growing operational concern due to the increased frequency of extended durations of missions (6-8+hours) in support of Operations Iraqi Freedom and Enduring Freedom. Endurance aspects of the currently used rotary wing seating systems were not optimized for the longer missions and wide range of pilot anthropometric measurements, which is now typical of naval aviation. The current seating systems were designed primarily to meet crashworthiness requirements, not for the wide range of pilot anthropometry or to mitigate WBV. Albeit, an issue, pilot fatigue and reduced mission effectiveness are also critical concerns. Current Hazard Reports indicated that pain in pilots’ legs and backs begin two to four hours into the flight and increase with time. Mission readiness also decreases with an increase in flight duration due to the constant distraction of pilots shifting in their seats while trying to get comfortable. Froom, et al [2] reported a dose-response relationship between the length of military helicopter flights and back discomfort. He also concluded that this pain is typically dull, over the lower back, and its prevalence and intensity are dependent on the total flight hours of exposure. Methods This study evaluated WBV produced in the pilot seating systems onboard the MH-60S. The purpose of the study was to test and compare the effectiveness of two different seat cushions, the current seat cushion versus an anti-vibration seat cushion. Both seat cushions were measured for acceleration levels averaged over five-minute intervals using a triaxial seat pad accelerometer. The recordings were completed for a 3-hour straight and level flight. A frequency analysis from 0-80 hertz (Hz) was conducted on all acceleration measurements to determine the dominant axis and frequency of the pilots’ vibration exposure. The results were then compared to the applicable Threshold Limit Values (TLVs) established by the American Conference of Governmental Industrial Hygienists (ACGIH) [1] and the International Organization for Standardization (ISO) 2631.1 [3] to determine the MH-60S pilots’ permissible exposure time for both seat cushions. Results The results of the study showed that for both seat cushions the vibration levels of the z-axis at 16 Hz had the shortest allowable exposure duration, according to the ACGIH TLVs. In the z-axis at 16 Hz, the MH-60S’s current seat cushion’s acceleration levels indicated an exposure time limit of approximately 6 hours, while the anti-vibration seat cushion’s acceleration levels pierced the 8-hour exposure time limit curve. This is shown in the graph below.

Jan 6, 2006

By D. Harrington

"Coal—mine explosions are accidents that can and should be prevented. In former years hundreds of lives were lost each year in the United States as a result of such explosions, but after 1932 the numerous precautionary measures adopted had reduced their frequency and severity 75 percent or more until in 1940 several very disastrous explosions marred the good record. Unfortunately, both the number and severity of explosions seem to be tending to increase compared with the relatively good achievement from 1933 to 1940. The requisites for an explosion are ever present in all soft-coal and many hard-coal mines. A certain combination of circumstances, such as a flame or an arc in a cloud of dust or in a body of gas or both may start an explosion at any time. The fact that the frequency and severity of explosions were lowered for 6 or 7 years is no guarantee that such freedom from explosions will continue, as the bad record of 1940 has shown, and underground workers should feel honor bound to exercise the utmost care so that they will not help to bring about the circumstances that will cause an explosion.Although mine operators bear the main responsibility for preventing explosions, miners can do many things to help. As about 9 out of 10 explosions begin at a working face, it is largely within the power of workers to prevent them. All miners should do their part willingly and should not defend a fellow workman from punishment, even from discharge, for disobeying necessary rules, whose disregard may cause the death not only of the safety-rule breaker but also of many of his coworkers.When a miner is careless and is injured some other way than by an explosion he may be the only one to suffer, but if his carelessness causes an explosion he not only endangers his own life but also that of every other man in the mine and possibly the lives of persons outside the mine.Experiments have shown that ignition of as small a quantity as 150 cubic feet of an explosive mixture of methane and air under certain circumstances can start an explosion that will traverse an entire mine. Thus, ignition of an explosive mixture of gas 1 foot down from the roof and 13 feet back from the face of a 12-foot entry might cause a widespread explosion if the right quantity and kind of dust were present. Many persons have ignited much larger quantities of gas without being killed, but they survived only because dust, confinement, and other conditions were not exactly ""right."""

Nov 1, 1940

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

THIS PROGRAM TRANSFORMS FREE FORHATED BRANCH DATA INTO A FORMAT SUITABLE FOR INPUT TO THE PENNSYLVANIA STATE UNIVERSITY MINE VENTILATION SIMULATOR (PSU/HVS 1. BRANCH RESISTANCES ARE ASSUMED TO HAVE BEEN ALREADY CALCULATED, IIOWEVER THIS PROGRAM CAN BE EASILY MODIFIED TO HANDLE THE ADDITIONAL INPUT DATA REQUIRED FOR RESISTANCE CALCULATIONS IN THE PSU/MVSO THE PROGRAM IS WRITTEN IN FORTRAN IV WITH WATFIV.

Jan 1, 1977

By Alexander May

In this Bureau of Mines publication stability constants for complexes of diethylenetriamine, 2-aminoethyl sulfide, triethylenetetramine, and 1,8-diamino-3,6-dithiaoctane with copper, nickel, zinc, and cadmium were deter-mined. The amine complexes were found to be much more stable than the analogous thio complexes. The results are interpreted in terms of possible molecular structure of the complexes.

Jan 1, 1974

By Gordon H. Dechman

This Bureau of Mines report presents an iterative approximation method for microseismic source location that was developed to adapt microseismic techniques for rock structure analysis to investigations of surface problems, such as slope failure in an open pit mine. The source location method and two derivative location algorithms are described in detail, and the speed and accuracy of the two algorithms are compared.

Jan 1, 1977

By S. A. Gustavson, H. E. Olund

This report has been prepared to review the history of the Premium Price Plan for copper, lead, and zinc, which was in operation from February 1, 1942, to June 30, 1947. It includes various charts and tables comparing costs and production data, and data on exploration premiums that were included in the Plan during the last year of its operation.

Jan 1, 1950

By Paul Zinner

Efforts to win an enriched manganiferous product from the Missouri Valley deposits of South Dakota have included an application of most known ore-dressing devices and have been largely unsuccessful. At least two methods showed some promise of success and were the subjects of detailed Investigation by the Bureau of Mines during the period from July 1945 to August 1947. A series of mining and beneficiation tests were undertaken to determine conditions under which the most feasible concentration methods could be employed and to define the limits of such applications in terms of the character of the final beneficiated product. In the absence of a significant current market for any conceivable product of beneficiation, the extent to which applied methods might be considered successful was measured in terms of ratios of recoveries to grade, regardless of the adaptability of such beneficiated products to further metallurgical or direct usage. The results of all investigations show that production of a shale-free, concretionary, manganese-bearing product by any known method requires great sacrifices in manganese recovery. Products of beneficiation, with specifications permitting some inclusion of shale, can probably be most effectively produced by methods employing specialized jigging equipment as the principal functional unit of a process.

Jan 1, 1949

By R. R. Allen

[The utilization of Western coals and lignite is a continuing study of the Bureau of Mines, and storage of these fuels is of paramount importance. Since the seasonal demand for coal in the Western States triples between the summer and winter months, successful storage of these low-rank fuels would tend to level out this variation and should reduce fuel costs. The time is rapidly approaching when the West Coast States, particularly California, will annually import several million tons of coal from the Rocky Mountain States for additional power production. This will necessitate storage of large quantities of coal, and it is thefore important to develop experience in such storage. Dry surface storage, by virtue of its flexibility and low cost, is particularly adapted to the stockpiling of large quantities of coal. This report will, therefore be primarily concerned with such storage. Inasmuch as the problems of dry, open-pit storage are quite similar to those of surface stockpiling, experiences in pit storage will be discussed briefly. Although spontaneous combustion is a hazard in storing coal, experience has proved that heats can be avoided by proper stockpiling procedures. The purpose of this report is to show that the most reactive coals can be stored satisfactorily on the surface by avoiding segregation and by thorough compaction.]

Jan 1, 1954

By A. C. Smith

The U.S. Bureau of Mines evaluated the effectiveness of automatic water sprinkler systems on the suppression of incipient and propagating conveyor belt fires under ventilated conditions. Large-scale experiments were performed at airflows ranging from 1.1 to 4.6 m/s. In incipient fire experiments with 100°C, standard-response sprinklers installed above and between the belts, the sprinklers activated later, the peak heat release rates were larger, and more belting was consumed at the higher airflow. In similar experiments with 74 °C, fast-response sprinklers, the sprinklers activated at the same heat release rate for both high and low airflows, but the peak heat release rate and amount of belting consumed was slightly higher at the lower airflow. In incipient fire experiments with sprinklers located only above the top belt, the heat release rate and amount of belting consumed was larger at the higher airflow. The propagating fire experiments showed that sprinklers located above and between the belts were effective in stopping flame propagation. Peak heat release rates and amount of belting consumed were larger at the higher airflows for both the 74 °C, fast-response and 100 °C, standard-response sprinklers. The sprinklers were equally effective at each airflow.

Jan 1, 2010

By Alan G. Mayton

A prototype end-cab shuttle car (SC) design has been developed to improve protection and address ergonomic concerns of the SC operator in low coal mines. The new design features an end cab transversely mounted to the SC and equipped with a closed-circuit video system. The end cab was retrofitted to a low-coal SC and evaluated in surface trials at the U.S. Bureau of Mines. During surface trials, test operators evaluated the end-cab SC relative to visibility; cab features-space, seating, controls, and operator position; tramming-inby, outby, and turning corners; and dumping. Trials were conducted using 12 test subjects; 6 were experienced SC operators. Results of the trials were promising. Of the experienced operators, the only operator with low-coal experience gave the new design the highest rating. Four experienced operators rated the end-cab design "better" to "much better" than a standard center-driven, side-cab SC for visibility when tramming, protection from roof and rib hazards, and no change in seat position with direction of travel. This report discusses research to modify a used 21SC JOY SC, retrofit the SC with the Bureau-developed end-cab, and evaluate the retrofitted end-cab SC in surface trials.

Jan 1, 2010