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By P. C. Good

This Bureau of Mines report describes the preparation of phosphoric acid directly from phosphate ore, without prior beneficiation, in a small-scale, continuous process research unit, as part of an effort to improve minerals and metals recovery from domestic resources while minimizing environmental effects. Three phosphate-matrix samples, ranging in grade from 18.2 pct P20S5to 11.9 pct P205, were dry-fed at a rate of 1.82 kg/hr (4 lb/hr) to a continuous-circuit, 12-liter, single-tank digester to yield phosphoric acid and byproduct gypsum filter cake. Comparison with earlier data shows that a significantly improved filtration rate was attained in a single-tank reactor compared with that attained in a five-tank reactor train processing the same ore. Iron and aluminum impurities in the product phosphoric acid averaged about 60 pct higher than amounts reported in commercially prepared, concentrate-derived acid. All gypsum filter cakes prepared had a firm, sandy texture, rendering them physically suitable for stacking or landfill use. Introduction of dry attritioning and air classification approximately doubled the attainable filtration rate when the dry-beneficiated product was digested. In air classification, there was a 12-to 14-pct P205 loss. Depending on the technique used and the matrix grade, overall P205 recovery ranged from about 72 to 89 pct.

Jan 1, 1979

By R. V. Lundquist

This report describes results of tests on the desilication of solutions resulting from the leaching of lime-soda sinters. Desilication was accomplished by heating the solutions in an autoclave. A liquor relatively free of silica was obtained after 30 minutes of heating at 200 p.s.i.g. in the presence of lime. The addition of lime improved desilication, but the rate and efficiency of desilication was effected by the quality of lime used. The optimum quantity of lime for effective desilication was about 6 grams per liter. A lesser quantity gave poorer desilication, and a greater quantity increased the alumina loss without improving desilication. The alumina loss was approximately proportional to the lime added. A complex structure, called artificial noselite in this report, was the only silica bearing compound detected in the desilication precipitate. Other compounds present were Ca(OH)2 (calcium hydroxide), CaCO3 (calcium carbonate), and Ca [A1(OH)6]2 (hydrated tricalcium aluminate). Sodium carbonate in the leach liquor retarded the formation of the calcium aluminate; hence it decreased the alumina lost to the precipitate. The extraction of alumina from aluminum silicate materials by the limestone soda-sinter process has been investigated by the Bureau of Mines for many years. The process consists of the following major operations: Blending the aluminum silicate with limestone and soda ash in such proportions that dicalcium silicate and sodium aluminate are formed on sintering; leaching the sinter in a carbonated caustic solution to extract the soluble alumina; purifying the leach liquor by the precipitation of soluble silica (this precipitate is designated desilication precipitate in this paper); precipitating alumina trihydrate from the purified liquors by carbonating with carbon dioxide gas; and calcining the trihydrate to alumina. Commercial grades of

Jan 1, 1962

By John L. Dahle

This report documents the research efforts that were undertaken to design, install and test noise abatement devices for use on off-highway haul trucks operating in surface mines. The objective of the program was to reduce the environmental noise from haul trucks. The noise reduction devices that were developed utilized existing technology and were tested on a 50-ton haul truck. The efforts emphasized the reduction of noise emitted from the engine compartment which included the use of side shields, sound absorbing material, improved radiator shroud design, and a modulating clutch fan. Noise tests were conducted using modified SAE test procedures for measuring sound levels around a stationary and moving machine, and inside of the operators compartment. Test results showed a maximum of 4 dB(A) reduction measured 16 feet from the truck. Interior cab noise was reduced 6 dB(A) with the windows and vents closed.

Jan 1, 1983

By C. C. Anderson, H. H. Hinson, H. J. Snhroeder

"INTRODUCTION The Eunice field is one of a group in southeastern New Mexico producing oil and gas from so-called limestone-type reservoirs in which the productive strata are dolomite or dolomitic limestone ordinarily, wells in reservoirs of this type show wide differences in their productive characteristics, indicating erratic variations in porosity and permeability. Often there is a large difference in total footage of actual ""pay"" penetrated in neighboring wells and the vertical distribution of the ""pay"" within the productive strata varies. In the Eunice field there are few easily recognizable geologic markers to indicate true structural conditions of the oil-productive section, due to horizontal and vertical gradation in chemical compositions and lithologic characteristics of the strata. Geologic markers are found some distance above the oil-producing zones in this field and consequently they indicate only the general structure. Furthermore, no direct relation has been found between the general structure and the accumulation of oil within the reservoir.Many problems in well-completion and production practice have been met in the Eunice field because of erratic variations in porosity, permeability, in vertical distribution of ""pays,"" and the apparent departure from ordinarily accepted relations of oil accumulation to structure. A detailed study of the position and characteristics of the oil- and gas-producing zones aids production procedure. The methods employed in studying the Eunice field, discussed in this paper, may be applicable to other limestone-type reservoirs."

Jul 1, 1939

By W. R. Huff

This report describes the development and operation by the Bureau of Mines of a pilot plant designed for using high-volatile A bituminous coal-in-water suspensions as a source of preheated coal and superheated steam in the pressure gasification of coal with oxygen. Figure 1 on page 2 is a block diagram of the integrated gasification process, in which a total of 70 tons of coal was fed from slurry and gasified. The present work included (1) development of equipment and methods both for mixing pulverized coal and water to produce slurry and for pumping and metering the slurry at gasification pressure; (2) development of equipment for heating the flowing slurry and, because slurry that can be pumped produces more steam than is necessary as a gasification reactant, developing equipment for removing and metering the excess steam; and (3) demonstration of the process under actual gasifier operating conditions, at a coal rate of about 800 pounds per hour and gasification pressures in the range 100 to 300 pounds per square inch gage. By using the forced-convection principle, a flow of slurry made from a caking, high-volatile A bituminous coal can be continuously heated to 600° F. in a coil-type heater. The flow rate and concentration of the slurry and the temperature gradient along the length of the heating coil must be closely controlled. In a radiant-type heater, involuntary reductions in flow rate, even momentary, can lead to coking and plugging of the heater coil.

Jan 1, 1961

By Dean H. Ambrose

This Bureau of Mines publication summarizes the status of mine electrical equipment reliability research. Failure rate data were estimated from theoretical, laboratory, and field studies. Tables are presented listing reliability characteristics of molded-case circuit breakers, undervoltage relays, ground check monitors, cables, motors, and control circuitry. Application of failure rate data is shown in tables listing maintenance scheduling intervals of components and components that are most sensitive to the probability of hazardous voltages on power distribution systems in the mines. Complete, accurate, and appropriate failure rates on mine equipment are of the utmost importance for reliability evaluations.

Jan 1, 1985

Objective: Construct a research facility to test sensor technology and engineering controls and to increase awareness of the proper functioning of mine hoists. Improve saferty and prevent injuries and fatalities to vertical movement of personnel and meterials in mine shafts and ore passes.

May 1, 1997

To evaluate the effectiveness of dust collector bags for reducing dust liberation from a roof bolter dust collection system.

Jan 2, 2007

To improve operational effectiveness of enclosed cab filtration systems. Background Enclosed operator cabs are widely used on mobile excavation equipment in the mining and construction industries. They protect the operator from bad weather, noise, and airborne dusts. The inside cab environment usually must be kept at very low dust concentrations because of quartz dust generated from the excavation of silica-bearing rock. Most cab designs achieve heating and air conditioning effectiveness by recirculating most of the interior cabin airflow, with a smaller portion of the outside air added to the cab as makeup air. Both the recirculated cab airflow and exterior makeup air added to the cabin should be efficiently filtered, with the makeup air positively pressurizing the cab interior. Ideally, operator cab air filters should provide at least 99% capture efficiency for dust particles as small as 0.3-pm aerodynamic diameters. These higher efficiency air filters provide good dust control for the equipment operator, but tend to accumulate dust more quickly than lower efficiency air filters.

Jan 1, 2001

By W. E. Robinson

Sixty samples, selected from a 2,300-foot core of the Green River Formation in Colorado, were studied to ascertain differences in the structure of the organic material present in the oil shale samples. Emphasis was placed upon relating differences in the aromatic content of the insoluble kerogen and the alkane content of the extractable material obtained from the selected samples. The methods used in determining these differences consisted of fractionation of the soluble material, carbon and hydrogen analysis, volatile material determination, carbon residue determination, oxidation rate determination, and infrared analysis. In general, it was concluded that the organic material in this core does vary in chemical structure and that same of these variations resulted from factors related to depth of burial. Other observed changes in structure of the organic material were not depth-dependent and resulted from other factors such as source material variations, biological alterations, or ecological differences.

Jan 1, 1971

By Donald F. MacDonald

This report aims to discuss, from the viewpoint of the mining geologist, the bearing of topographic and geologic conditions on cer- tain problems that arose in the construction of the Panama Canal. T+ is published by the Bureau of Mines as a contribution to engineer- ing liters ure because it presents information that shows how geology and topography must be considered by the mining engineer in plan- ning excavations and in removing loose material and solid rock in the safest and most efficient manner. The printing of this bulletin has been approved by the governor of the Panama Canal, as it was impracticable for the Panama Canal to give this information to the general public in any of its publications. The "sword cut" of Goethals and his men did not sever the Isth- mian barrier; it merely clove the hills to a depth of 40 feet above sea level. This cut and the great areas of low valleys at both ends of it have been covered with fresh water to the 85-foot level. This high-level lake held by dams at either end, the 85-foot locks, by which ships enter it, and the dredged approaches from the two oceans constitute the Panama Canal. In the preparation of accurate estimates concerning the cost of large excavations information regarding the geologic conditions, as obtained by a study of natural features, is necessary. Drill holes and test pits will furnish supplementary geologic information, but without a gen- eral knowledge of the geologic conditions it will not be possible for the constructing engineer to answer such questions as the following: (1) What rock units will be encountered in the excavation and in what proportion? (2) What will be the cost of drilling each for blasting (3) How far apart and how deep must the drill holes be to efficiently break the rock of each to the proper size-not too fine nor yet too coarse? In this connection jointing, fissuring, bedding, toughness, and other physical characteristics must be considered (4) How steep will the slopes of the excavation stand, and to what extent will they wash and trench on exposure to the atmosphere? (5) What proportion of the material to be excavated is of such physical character that it may be utilized in any other part of the project, such as in concrete construction, road making, wharves, breakwaters, riprap work, etc.

Jan 1, 1915

By H. E. Harris

An extensive experimental program was carried out to determine the variability of respirable dust samplers and to determine whether area dust sampling is feasible in coal mines. For sampler variability, it was found under laboratory conditions, that a single dust measurement could be as much as 0.30 mg/M3 from the true value at the 95% confidence level. Under actual underground mining operations, this difference could be as much as 0.52 mg/M3 in the 0 -5.0 mg/M3 range. The results from dust sampling on 175 production shifts involving over 2,500 on-man and area dust samples showed that area sampling is viable, but the field investigation did not establish necessarily where the best area locations were.

Jan 1, 1976

By Townsend. James W.

"INTRODUCTION As a byproduct of its mineral investigation program, the Bureau of Mines has developed a number of operating devices and techniques worthy of note. This paper, prepared under the direct supervision of Paul T. Allsman, chief, Salt Lake City Division, Branch, and under the general supervision of Lowell B. Moon, chief, Mining Branch, reports upon one such device. A simple device has been developed for measuring angles of deviation from the horizontal as recorded on a glass tube by acid etching. The device has facilities, also, for measuring the angle between the long axis of the ellipse and the north-south reference points established by a Maas compass or from an established axial lamina, on the tube, which was ori¬ented to a specific direction in the hole by rod alinement.The device was found accurate within half a degree on repeated orientations of the same tube. However, the degree of accuracy is dependent on the accuracy of personal manipulation in orienting the tube to the correct plane."

May 1, 1947

By Michael J. Friedel

The integrity of mine structures, such as the roofs, ribs, face and supporting pillars, is difficult to assess beyond the exposed surface. To mitigate potential rockfall hazards, the U.S. Bureau of Mines is assessing the usefulness of Rayleigh wave dispersion analysis to detect damage and stress-relieved zones in mine structures. Classical surface wave dispersion modeling is utilized at both laboratory and field scales in damaged and undamaged material to assess the integrity of a mine pillar and roof. To more fully exploit Rayleigh wave propagation characteristics, derivation of a novel dispersion parameter was conducted using a convolutional model. The development of a suitable Rayleigh wave dispersion system based on insight derived from forward modeling is presented. The application of inverse modeling for damage and stress assessment in the mine environment is also discussed.

Jan 1, 2010

By Glenn C. Reed

The Sheep Creek iron deposits, Meagher County, Mont., were investigated by the Bureau of Mines in 1943 and 1944. Work undertaken included exploratory trenching, churn drilling, petrographic studies, and detailed beneficiation tests. It was determined that the Sheep Creek ores occur both as fissure filling and bedding replacements in thin-bedded shale and arenaceous limestones of the Algonkian Belt series. At least five stratigraphic horizons were found to be mineralized. Metallurgical studies indicate that the ores are not amenable to beneficiation by present-day low-cost methods. Details of geology, sampling, and beneficiation tests are presented in this report.

Jan 1, 1949

By G. W. Birge, D. E. Wolfson, J. G. Walters

An investigation was conducted to determine the relationship between ASTM and Micum tumbler data and to develop equations that would enable the conversion of data from one test method for comparison with those determined by the other , and thereby facilitate the international exchange of data . Relative strengths of 18 commercially produced cokes were determined by ASTM and Micum tumblers and ASTM shatter test . Two of the samples were coke produced for foundry use , and two were produced in beehive ovens . The remaining 14 samples were produced for blast furnace consumption and had ASTM tumbler stabilities of 36 to 58. Statistical procedures were used to relate the three test methods and also to evaluate the effect of charge weights , top sizes of coke , and types of screens specified by the two standard tumbler procedures , square - hole wire mesh for the ASTM tumbler and punched round - hole for the Micum . A significant result was that the data obtained with like screens have a higher degree of correlation with a smaller standard deviation than data from the screens specified for each tumbler .

Jan 1, 1964

By L. C. IlsLey

"There are two general classes of accidents that prevail in and about mines, namely - (1) those that through the nature of mining work can only be lessened, and (2) those that by proper precaution can be eliminated altogether. Explosive accidents that ordinarily take place while explosives are being transported in and about mines belong to the second class, that is, by proper care all such accidents can in general be avoided.The following table gives a brief summary of several accidents and disasters that have occurred in the United States and indicates the need of universal preventive measures as a basic part of all State regulations.ACCIDENTS AND DISASTERS OCCURRING WHILE TRANSPORTING EXPLOSIVES.***"

Sep 1, 1923

This report describes a U.S. Bureau of Mines investigation into the removal of gate road chain pillars in conjunction with longwall retreat mining. The research objective was to determine, through evaluations of the loads imposed on the gate road pillars and supplemental support elements in the entries, how the pillars, supplemental support, and entries were affected by the longwall abutment pressure. To achieve this goal, vibrating wire stressmeters and hydraulic flat jack pressure cells were installed in the support elements to monitor stress change caused by abutment pressure as a function of longwall face advance. The findings documented in this report are the result of information collected from instrumentation and observation at the mine. Pillar and support loading measurements and stability observations revealed that the roof and the support elements remained stable during panel retreat, while the face progressed at a normal rate of advance. The ability to safely and efficiently mine chain pillars during panel retreat increases resource recovery and can provide several other benefits described in this report.

Jan 1, 2010

By L. A. Morley

Volume IV of the final report examines the problem of indirect contact of overhead high-voltage power lines by mining personnel. This refers to the contact of energized lines by workers through some intermediate conductor such as a metallic tool or a piece of high-reaching mobile equipment, thus the term "indirect contact." The shock hazard presented by such contact has been a major cause of electrical fatalities associated with mining operations. The report volume is divided into three major areas. The first gives a general background of overhead lines, basic characteristics, and associated hazards, and continues to describe presently used techniques and devices which attempt to alleviate the contact problem. The second area narrows the discussion to the mining industry by presenting a detailed analysis of 39 overhead-line contact accidents in mining since 1970. The third major section uses the information from the first two areas to formulate recommendations to prevent these accidents and subsequent electrocutions at mining operations.

Jan 1, 1982

By C. V. Jude

This U. S. Bureau of Mines (USBM) report presents results of stress analyses and field observations to investigate the effects of elevated trench drifts on the structural stability of rock mass zones surrounding a production draw drift in a mine utilizing a mechanized load-haul-dump (LHD) trench undercut panel caving system. A two-dimensional boundary-element mine stress model was developed to predict the locations and extent of damaged rock mass zones surrounding draw drifts where adjacent, parallel trench drifts are either elevated or not elevated above the LHD production draw drift level. A Mohr-Coulomb shear-failure criterion was obtained directly from in situ borehole shear test data. Hock-Brown shear-failure parameter values were computed from borehole-shear and triaxial test data. A procedure is described to estimate these parameters when a rock mass rating (RMR) value and triaxial data on intact samples exist, and no borehole shear test data exist Results indicate that trench drifts, elevated to the level equal to the height of the LHD production draw drift, would not minimize material damage nor significantly enhance the stability of rib and crown pillar zones surrounding production draw drifts in the mechanized LHD trench undercut caving panel investigated at this mine.

Jan 1, 2010