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By E. R. Spencer, E. Reeves

National Institute for Occupational Safety and Health (NIOSH) researchers conducted an investigation to quantify sound levels and to determine the amount of sound reduction provided by engineering noise controls installed in a talc processing plant. Baseline sound level and sound intensity measurements were performed at the plant and the measurement locations were recorded for comparison to post-control measurements. Follow-up measurements were then made at the same locations after the initial noise controls were installed. The plant subsequently decided to implement additional noise controls and the researchers returned to conduct measurements for a final analysis of all noise controls. The most significant results showed a sound level reduction in the main mill area from a range of 93-104 dB(A) down to 90-94 dB(A), and a total sound power level reduction of 21 dB(A) for air classifying mill 3.

By J. S. Kennedy, R. G. Omeara

Beryllium is a strategic metal of ever-increasing peacetime importance because of the unusual properties of beryllium-copper alloys. These unusual characteristics are the combination of high strength and hardness, high fatigue resistance, and high wear resistance in alloys that have the corrosion resistance of copper. The principal industrial source of beryllium is the mineral beryl, a beryllium-aluminum silicate that occurs in pegmatites associated with quartz, feldspar, mica, and smaller amounts of various accessory minerals. The beryl is usually recovered in processing the pegmatites for the recovery of some of the other mineral constituents. Pegmatite deposits are found in various parts of the United States, but those in the Black Hills of South Dakota are the source of most of domestic production. The beryl marketed from the South Dakota pegmatite deposits occurs as coarse crystals, which are obtained by hand sorting. These pegmatites also contain other valuable minerals.

Jan 1, 1948

By Louis A. Panek, John A. Stock

A flat slot is created in rock to cause stress relief effects in a pair of hydraulic borehole pressure cells (previously installed in drill holes above and below the slot ) , which act as sensing devices . This relief is annulled by repressuring the slot by means of a flat hydraulic cell . The slot pressure at annulment is taken to be the existing ground stress at right angles to the plane of the slot . A number of trial installations in the rib of a mine drift showed that for a valid determination of ground stress the sensing devices that respond to relief and repressuring must be within a specified zone close to the pressure transmitter ; otherwise the indicated ground stress may be excessive . By using an additional pair of borehole pressure cells , installed a few feet away , the existing rock stress can be redetermined at intervals , irrespective of a change of stress intensity subsequent to the initial installation . Based on these findings , equipment and procedures have been developed that make possible the installation and operation of a permanent rock stress monitoring station for observing mining - induced stress changes . The station consists of a 12 - in - wide hydraulic pressure cell cemented in a flat slot and four 2- by 8 - in flat hydraulic pressure cells in nearby drill holes . All drilling for the installation can be done with an air leg drill and conventional bits . Once the installation is completed , all required information is obtained by Bourdon pressure gage readings . The apparatus is simple , relatively inexpensive , and reliable under operating conditions in a wet mine . Unlike most methods of rock stress determination , this scheme permits periodic remeasurement of absolute rock pressure over several years , without additional drilling or instrumentation . Similar to other flat slot procedures , stress measurements are obtained without making auxiliary tests to determine elastic

Jan 1, 1964

By C. E. Jordan

The fundamental properties of dielectric separation were studied to provide insight into the design and operating characteristics of a dielectric separator. Force equations on mineral particles were derived and evaluated experimentally. Responses to variations in the electrical voltage and frequency, feed rate, particle size, dielectric fluid, and dielectric constant were tested theoretically and experimentally, using a 5-cm-diam dielectric separator. High-dielectric mineral recovery was proportional to the calculated effective dielectric force volume (EDFV) that surrounded each drum-electrode wire. Electrode spacing was the most sensitive design parameter; spacing of less than 0.4 cm was required for a good separation. Dielectric separation was effective for separating minerals with dielectric constants that differed by approximately 2 or more.

Jan 1, 1985

By J. R. Sweet

The paper describing the raining operations at the Mt. Hope mine, Mt. Lope, N. J., is one of a series being prepared by the United States Bureau of Mines on mining methods, practices, and costs of various mining operations in the United States. Mt. Hope mine produces magnetite ore. It is situated in the general northern part of the State of New Jersey. The towns of Rockaway, Wharton, and Dover lie within a radius of 4 miles from the mine. Dover is 40 miles from New York City.

Jan 1, 1932

By Fred W. Snow

This paper describing the mining practices at the Magma mine, Superior, Ariz., is one of a series being prepared by the Bureau of Mines on mining prac¬tices, methods, and costs in the various mining districts in the United States. At present (1929) practically all the mineral production in the Superior district is from the Magma mine of the Magma Cooper Co. The ore is mined for its copper but contains associated silver and gold. Both direct smelting ore and ore of concentrating grade are produced. The mining methods now in use at the Magma mine were adopted or developed as knowledge was gained of the physical condition of the ore bodies and the inclosing formations; the wall rock is soft and crushed and the ore is relatively hard. In general, existing methods have been adapted to fit local conditions, but some of the mining practices used were originated at this mine. Most of the ore is mined by a combination of rill stopes and pillar stopes. The pillars are extracted by underhand mining.

Jan 1, 1929

By Austin Gudmundsen

"The smoke nuisance, like many other undesirable and longstanding features in our present civilization, is still with us. On reviewing the situation we are astonished to find no authentic record of a major smoke-abatement campaign that has succeeded in eliminating a smoke nuisance, in spite of the fact that the problem has been with us since the use of bituminous coal began. We might well ask ourselves where the trouble lies; is the problem impossible of solution? We can not blame the average citizen for harboring this thought as a conviction. He has been urged for so long but sees so little evidence of progress. He has repeatedly been assured by the scientist and the engineer in most convincing terms that smoke. is unnecessary, that it can be avoided; small wonder is it that he is beginning to distrust so-called authority on the subject.On the other hand, the scientist and engineer are entirely within their rights. We all know that even high-volatile coal can be and is now being burned with no visible smoke. We know that even small domestic heating furnaces, with favorable conditions and with proper care, can be fired by hand without producing much smoke. And we know that when such equipment is fitted with suitable stoking devices, little or no smoke results. What, then, is the answer?Perhaps we may learn something from a critical examination of a typical smoke-abatement problem. Probably one of the most enlightening campaigns that has been waged in the United States is that of Salt Lake City, Utah; therefore, the purpose of this paper is to discuss the important aspects of this particular case."

Apr 1, 1930

By J. Alton Burks

When acoustical materials are used in a mining environment for noise control purposes, they are subject to environmental deterioration from hydraulic fluid, moisture, and dust. These and other factors can cause physical degradation of the material, which can lessen its ability to absorb sound. In this study, the Bureau of Mines measured the sound absorption properties of 16 different acoustical materials after 4 sample treatments: (1) being kept clean and dry (as received from the supplier), as a control or reference standard, (2) immersion in water and draining, (3) immersion in lOO-pct-petroleum-type hydraulic fluid and draining, and (4) exposure in a coal mine. The last three treatments were used to approximate the type of physical degradation that can be experienced in actual use. The impedance tube or standing wave method was used to measure the normal absorption coefficient. It was found that the absorption coefficient of most materials was adversely affected by the retention of either oil or water, with oil having the greater effect. The only class of materials that was affected by neither oil nor water was neoprene foam.

Jan 1, 1990

By Paul M. Tyler

One of the best present-day yardsticks of the material welfare of a nation is its consumption of minerals, The United States, with only 7 percent of the world population, consumes 45 percent of the world wealth, pays the highest real wages, has the shortest working hours, and numbers the largest percentages of home owners among its population, and at the same time its per-capita consumption of minerals is far greater than that of any other nation. In 1937, British India, with roughly twice the population of the United States, used less than 2 percent as much lead, 4 percent as muck zinc, and 13 percent as much copper; even in Europe, which has three times our population and where war preparations have greatly expanded the normal needs of peaceful industries, the aggregate consumption of metals and industrial minerals other than lignite is less than the total for the United States alone. The march of civilization passed from the Stone Age to the Bronze Age before the dawn of history. It may be questioned whether man or monkey first threw stones at an enemy, but only man could have fashioned rough stones into weapons. Eoliths rudely shaped by apelike men are believed by archaeologists to have antedated by hundreds of thousands of years the existence of our own human ancestors. The primitive people that followed the retreating Ice Cap northward in early quaternary period - at least a million years ago - were fairly adept in the shaping of flints and even used a little copper. The Bronze Age, so-called, superseded the Stone Age when, around 8,000 B. C., the news spread that chunk s of natural copper could be pounded into better weapons or cutting implements than ever could be made by chipping stones. The Bronze Age gave place to the Iron Age about 1,000 B, C., and though students of modern history may speak of the Coal Age, the Petroleum Age, and the Automobile Age, and so on, these ages have all been crowded into a brief century and a half. The truth is that we still are in the Iron Age, unless perhaps we choose to call it the Age of Many Metals.

Jan 1, 1940

By J. P. May

This U.S. Bureau of Mines report identifies and evaluates factors responsible for dump-point accidents involving mobile mining equipment. Information regarding the occurrence and severity of the accidents, the industries affected, the types of equipment involved, the primary and contributing causes, and pertinent Federal regulations is included. The aim of this report is to provide information that will aid mine operators in the recognition of hazards associated with mobile equipment operation near the dump points of stockpiles and waste dumps.

Jan 1, 1990

By J. D. Davis

THE carbonizing properties of one medium- and and five low-volatile coals from West Virginia and one high-volatile A and two medium-volatile coals from Pennsylvania were determined by 800° and 900° C. BM-AGA carbonization tests and expansion tests in the sole-heated oven. Plastic properties of the coals and the yields and quality of their cokes and other carbonization products were determined. The low-volatile coals comprised a mine and a coke-plant sample of Pocahontas No. 6-bed coal from the. Black Eagle No. 1 mine, Wyoming County, W. Va.; a mine sample of Pocahontas No. 6 bed from the Louisville mine, Mercer County, W. Va. ; Davy Sewell bed was sampled at the Twin Branch mine, McDowell County, W. Va.; and Fire Creek bed was sampled at the Dunedin No. 1 mine, Raleigh County, W. Va. The medium-volatile coals were from the Fire Creek bed, Laurel Creek mine, Greenbrier County, W. Va.; Lower Kittanning bed, Springfield No. 4 mine, Cambria County, Pa.; and Upper Kittanning bed, Springfield No. 6 mine, Clearfield County, Pa. The high-volatile A coal represented the Upper and Lower Freeport beds, Kent Nos. 1 and 2 mines, Indiana County, Pa. In addition to the coals listed, high-volatile A coal from the Pittsburgh bed, Warden mine, Allegheny County, Pa., a standard blending coal, was used in blends in this investigation.

Jan 1, 1950

By R. W. Watson

In January 1980, the Bureau of Mines initiated an experimental program to examine the fire and explosion hazards of one-hour self-contained self rescuers (SSRs). This action was prompted by a growing concern on the part of government and industrial safety officials over the potential hazards of these devices when deployed on a large scale in underground coal mines. Prior evaluation of the safety of these devices had been at best sporadic and usually limited to experimental models. The recent availability of preproduction models of a l-hour SSR fabricated by the Mine Safety Appliance Company* and a production model manufactured by Dragerwerk Ag Lubeck of the Federal Republic of Germany allowed for a more comprehensive and meaningful evaluation of their safety in underground coal mines. This report summarizes the results of a 5-month study of the potential hazards of these two items. During the course of the work, periodic progress reports were presented to officials of the Mine Safety and Health Administration and various mining organizations including the American Mining Congress, Bituminous Coal Operators of America. National Independent Coal Operators Association, and the United Mine Workers of America. The free exchange of ideas that occurred during these meetings had a significant impact on the direction of this study and a serious attempt was made to address all of the issues that were raised at these meetings. The authors are extremely grateful to the individuals that participated in defining the specific problems that could arise as a result of deploying the self-contained self rescuers in an underground coal mine environment.

Jan 1, 1980

By H. W. Kilau

The Bureau of Mines tested chromium-bearing waste slags from industrial stainless steel and other chrome alloy operations to determine their chromium leachability characteristics under acid precipitation conditions and to devise measures to prevent any pollution originating from this source. Two critical slag composition factors were found to control the chromium leachability: (1) CaO:Si02 ratio and (2) magnesium content. Above a 2.0 CaO:Si02 ratio, chromium exists in slag as CaO·Cr203, which can be vulnerable to leaching by acid precipitation especially if oxi-dized to CaCr04 when exposed to the environment over an extended period. Maximum chromium leachability from industrial slags occurred when the composition of the slag had about a 2.0 CaO:Si02 ratio. Between a 1.0 and 2.0 CaO:Si02 ratio, in the presence of sufficient magnesium, MgO ·Cr203 was formed, which is very resistant to oxidation and to dissolution by simulated acid precipitation. Addition of magnesium silicates to molten slag to fix the chromium in the MgO·Cr203 form was successful in preventing chromium leaching in simulated acid rain solutions. Experiments showed olivine and waste taconite tailings were suitable for this purpose. Olivine addition to a waste slag having a composition vulnerable to leaching (CaO:Si02 > 2) reduced the chromium leachability more than 80 pct.

Jan 1, 1984

By C. Daniel Kealy

Finite-element,, mathematical models that solve LaPlace's and Richard's equations numerically were used to locate the phreatic surface within tailings pond embankments and to define the subsurface flow of water from the pond. Both must be known to design structurally and environmentally safe tailings dams. The permeability distribution within and beneath the embankment, the fluid potential values upgradient and downgradient from the embankment, and the geometry and elevation of an approximately impermeable layer at some depth beneath the embankment were used as computer inputs in analyzing over a dozen finite-element models of tailings dams varying structurally from simple to complex. Results predicted with the finite-element model were confirmed with measurements in a laboratory model of a tailings pond and in the field. Of particular importance to the design of safe slopes, all data indicated that the phreatic surface within a tailings dam is concave upward, a configuration opposite that in most earth dams. The close correlation between predicted and experimental values confirmed the practicability of using the finite-element technique to design safe tailings dams.

Jan 1, 1971

By Paul W. Johnson, Ralph C. Kirby, Frank A. Peters

A series of economic evaluations of processes for producing metallurgicalgrade alumina from low- grade aluminous materials is being conducted by the Bureau of Mines to determine the relative processing costs . The two processes considered in this evaluation are concerned with the recovery of alumina from clay through the formation of ammonium alum . In the first process , dehydrated clay is leached with ammonium bisulfate solution ; in the second process , clay is baked with ammonium sulfate and then leached with water containing a small quantity of sulfuric acid . After the alumina is dissolved by either of these methods , the iron is reduced to the ferrous state to avoid crystallization of ferric sulfate with the alum . The recovery of pure alum requires two crystallization steps . The alum crystals are then redissolved and precipitated with ammonia to produce alumina hydrate , which is calcined to a - alumina . These evaluations are based on published work , and the proposed plants are designed for a capacity of 1,000 tons of alumina per day . The estimated operating cost per ton of alumina for the bisulfate leaching process is $ 117.06 , and for the sulfate baking process , $ 109.26 . Using a Marshall and Stevens chemical equipment index basis of 240.0 , the estimated fixed capital costs , in the same order , are $ 158 million and $ 146 million . Under current economic conditions , these two processes are not competitive with the Bayer process for the production of alumina from bauxite . Since small improvements will not reduce costs sufficiently to approach competitive costs , future research work with these processes should be confined to areas likely to result in major cost reductions .

Jan 1, 1965

By D. D. Harbuck

To decrease reliance on foreign sources for the strategic and critical metals gallium and germanium, the U.S. Bureau of Mines identified and developed processing technology for two domestic sources of these metals: a Tennessee zinc residue and a Utah ore. Sulfuric acid (H2S04) solutions were used to solubilize gallium and germanium in both sources. Statistically designed experiments showed that the most important parameter for high metal extraction from zinc residue was the H2S04 concentration. At a concentration of 2.9M H2S04, 95 pct of the gallium was extracted, and at a concentration of 0.6M H2S04, 73 pct of the germanium was extracted. Controlled H2S04 concentration was also the key for high metal extractions (97 pct Ga, 87 pct Ge) from the Utah ore. Such control was achieved using a two-stage countercurrent leach circuit. Testing showed that the insoluble germanium in both the residue and ore was tied up with silica. Several methods for overcoming this problem are given. To recover gallium and germanium from the leach solutions, the solvent extractants octylphenyl acid phosphate (OPAP) (for gallium) and LIX 63-OPAP (for germanium) were identified. These extractants were tested in separate, continuous, solvent-extraction circuits yielding a gallium recovery of 94 pct and a germanium recovery of more than 90 pct.

Jan 1, 2010

By Harry R. Johnson

Laboratory experiments were conducted to study the carbon deposition characteristics of a high-gravity, paraffin-base crude oil. The results of these experiments indicate that a fuel supply adequate to initiate a combustion wave can be deposited in high-gravity-oil reservoirs. These results are significant because there has been considerable doubt whether oils over 35° API gravity are able to deposit sufficient fuel. Considered in these studies were the effects of air flux, temperature, initial oil saturation, and time on carbon deposition. Conditions that maximized carbon deposition in the laboratory and an understanding of the nature of carbon formation are shown by graphical interpretation of the data. Statistical techniques were used to design and analyze the results of the retort tests. For the same amount of laboratory work, this approach yields more information about the systems that were studied than the classical method of research presently used in many laboratories. In addition, the accuracy of calculating the effect of each variable on carbon deposition is twice that of the classical approach. This paper develops the statistical approach to research without complex mathematics, thus enabling the reader to grasp the concept of how statistics can be applied to study many complicated problems.

Jan 1, 1966

By V. B. Dale

This is one of a series of reports covering the mineral resources of the Nation. It describes briefly most of the known tungsten deposits in Yuma, Maricopa, Pinal, and Graham Counties, Ariz. Most of those described were examined by the author. An effort was made to determine the position of the various deposits by section, township, and range and to give accurate road direction to each property from a prominent landmark. All available maps have been used in making these determinations, but in unsurveyed areas it was necessary to make approximate projections of subdivisions. The township and range numbers refer to the Gila and Salt River base and meridian.

Jan 1, 1959

By F. B. Petermann

The Bureau of Mines conducted electric furnace smelting tests on sintered flotation concentrate and siliceous log-washed are. The flotation concentrate was derived from the Maggie Canyon deposit of the Artillery Mountains area, Mohave County, Ariz., and contained, before sintering, 35.6 percent Mil and 19.4 percent Si02 + A1203. The log-washed ore was from the McGregor deposit of the Artillery Mountains area, Mohave County, Ariz., and contained 31.2 to 33.6 percent Mil, 19.5 to 27.6 percent Si02 + A1203, and 2.5 percent Pb. This work was undertaken to determine the most effective smelting technique for producing standard products from such nonspecification ore and concentrates. The objective was to collect data, using a small furnace, which would be reasonably accurate and permit extrapolation to large-scale practice for comparing with results on specification-grade are.

Jan 1, 1962

By Paul W. Johnson

A computer program for calculating capital and operating costs from material and energy requirements and equipment costs for use in preparing cost estimates for metallurgical process evaluations has been written by the Bureau of Mines' College Park process evaluation group. The program permits rapid recalculation of processing costs when changes of data or equipment are desired, and produces tables of capital and operating costs suitable for publication. Equipment cost summary tables for each process section end supplemental information for input-data checking is included in the computer printout. The program is written in Fortran IV except for several subroutines which are written in machine assembly language for the IBM 7094.3 With a few modifications, the program can be used on other computers.

Jan 1, 1969