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By George A. Morgan

The 53 countries that constituted Africa in 1991 accounted for a significant portion of total world output of a number of mineral commodities. However, total output for the continent declined for many major mineral commodities produced compared with that of 1990. Also, Africa's share of total world output of these commodities generally declined. (See tables 1 and 2.) The most conspicuous declines were for cobalt and copper owing to mining and metal processing difficulties experienced by the world's two largest cobalt producers, Zaire and Zambia. Phosphate rock output declined primarily owing to a sharp fall in production from Morocco, also a leading world producer. Morocco's state corporation for phosphate production experienced marketing problems, leading to the decline.

Jan 1, 1993

By Carroll W. DeKock

Thermodynamic data for selected metal sulfates were critically evaluated and compiled as part of the Bureau of Mines program to provide a scientific base for use in developing new technology and predicting the feasibility of new processes. Values for Cp°, S°, H° - H°298, - (G° - H°298)/T, ?RC, ?Gf°, and log Kf as functions of temperature are given in tabular form. Thermodynamic data were compiled for Ag2SO4, A12(504)3, A12(S04)3?6H20, BaSO4, BeSO4, BeSO4?2H2O, BeSO4?4H20, CaSO4, CaSO4?1/2H20, CaSO4?2H2O, CdSO4, CdSO4?H20, CdS04?8/3H20, 2CdO?CdSO4, Cs2SO4, In2(S04)3, K2504, KA1(S04)2, KA1(S04)2?12H20, Li2SO4, L12SO4?H20, MgSO4, MgSO4?H2O, MgSO4?2H20, MgS04?4H20, MgS04?6H2O, MgS04?7H2O, Na2SO4, Na2S04?7H20, Na2SO4?10H20, (NH4)2SO4, NH4A1(S04)2, NH4A1(S04)2?12H20, PbSO4, Rb2SO4, T12SO4, and Zr(S04)2.

Jan 1, 1986

By S. H. Ash

Tunnel driving is recognized as one of the most hazardous of occupations; this is a reflection of the high accident severity rates and resultant high compensation and similar costs in this industry. Most tunnels are driven by contractors who bid for the jobs, taking into consideration the prevailing industrial insurance rates at the time the bids are placed. After the bid is secured the contractor then attempts to complete the job at the minimum cost to himself. In a sense the accident-cost item is fixed for at least one year when a policy is secured. Time is generally an important factor not only for the contractor, but also for the insurance carrier and the assured. If the assured represents a private interest, the cost burden usually is ultimately placed on the general public which avails itself of the service contemplated; if the project is a governmental enterprise the cost burden unquestionably falls upon the general public involved and on the general tax payer. For these reasons it is of vital interest to the public that accidents not only be kept at a minimum as a humanitarian objective, but also because the accident-cost burden, too frequently not even realized and considered to the degree that it should be, can assume proportions that materially affect the cost of the enterprise. The basic industrial insurance rate for tunneling in California in 1932 contemplated an earned premium of 12.12 percent of the labor pay roll. The State has been particularly engaged in large construction enterprises, some of which involve high accident cost rates, notably structural-steel bridge building, which contemplates an earned premium of 19.65 percent of the labor pay roll. When this figure is compared with the much lower rates that apply to other industries it is apparent that a heavy toll in human wreckage is taken by such engineering projects, which must be viewed as monuments to human suffering as veil as to human achievement.

Jan 1, 1933

By J. R. Thoenen

The enormous and constantly increasing demand for limestone to supply a multitude of uses is a remarkable feature of the mineral industries. As approximately 130,000,000 tons of limestone are produced annually, it is not surprising that deposits at or near the surface are gradually being exhausted and that less advantageous supplies are being worked. Quarries are becoming deeper and wider year by year, and in many places the volume of overburden that must be removed to allow open-pit work has increased alarmingly. Quarrymen are also gradually learning how expensive it is to sort and clean stone from a deposit overlain by poor material. As such conditions confront the limestone industry, the natural tendency is to seek some modification in method whereby the handicaps of increasing cost may be met and overcome. Operators, some of them unwillingly, have been forced to conclude that underground work in drifts and tunnels is the most logical solution of the problem. The unwillingness of some is largely due to unfamiliarity with mining and to the unfounded fear that costs must increase and dangers multiply when mining is undertaken.

Jan 1, 1926

By Mandius C. Lundal

This report describes the work done to develop a coal mining machine to increase productivity and recovery from thin seams beyond the highwall, in addition to decreasing the miner's susceptibility to to highwall hazards First, radar transducers were adapted to measure coal thinkness and detect rock and coal interfaces; Then, the radar was incorporated into a cutterhead with steering controls. Next, visual displays were designed to show cutter position in the coal seam, and anticipated change in coal seam inclination, Finally, development of a telemetry system made remote control of the cutterhead possible. Simultaneously, a high-performance extended depth (HPxD) auger machine was designed with an automatic system to handle 600 ft of 36-in, diameter dual spiral flight conveyor sections. A two man crew controls all operations from a weather conditioned cab outside the VDZ, either at night or day time. As a primary mining tool, working 4000 hr/yr (2 shifts/day) recovering 60% of the coal 600 ft beyond the highwall, productlon to 500,000 ton/yr can be achieved. Volume I provides an overview of machine, systems and productivity.

Jan 1, 1977

By H. Reginald Hardy

This report is Volume I of a three volume final report on the micro-seismic monitoring of a longwall coal mine. Volume I deals for the most part with the detailed aspects of the microseismic field study itself, however, brief references are made to other secondary studies described in Volumes II and III. During this field study a mobile microseismic monitoring facility and associated transducers were employed to detect and record microseismic activity above a longwall panel at Greenwich Colleries, Barnesboro, Pennsylvania. The fundamental objectives of this study were (1) to evaluate the feasibility of detecting microseismic activity originating from longwall mining operations using an approximately planar, near-surface, geophone array installed above the longwall and (2) to attempt to locate the sources of the various microseismic events. This investigation has proven that, using the techniques developed it is possible to detect microseismic events at depths of more than 400 ft and at horizontal distances in excess of 800 ft from the source. The majority of the observed events were found to have frequencies on the order of 10 to 100 Hz, and particle velocities of 50 to 300 µips. When a suitable velocity model was utilized, most of the events located were computed to be within ±100 ft vertically of the coal seam and ±50 ft horizontally of the longwall face. The results of the overall research project suggest that additional research should be undertaken in a number of associated areas.

Jan 1, 1978

By Frank L. Wideman

"INTRODUCTION The Cphir Hill Consolidated mine was examined 2/ in January 1944. It was recommended that the mine be explored for the purpose of increasing of lead and zinc ore.The Bureau of Mines began exploratory work at the mine in June 1944 and completed it in June 1945. The work was planned to indicate ore that could be developed and extracted quickly and consisted of core drilling and trenching.ACKNOWLEDGMENTSIn its program of exploration mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. Its the policy of the Bureau to publish the facts developed by cash exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, O. C. Ralston, chief, analyzes samples and performs beneficiation tests.The work reported on in this paper was conducted under the supervision of S. R. Zinmerly, removal engineer of the Western Region, and J. A. Marsh, district engineer of the Utah-Wyoming district. Subsequent to May 1945, the project was under the supervision of Paul T. Allman, chief, Salt Lake City Division, Mining Branch. The management and employees of the Ophir Development Co. wore very cooperative. Credit is due to the Bureau employees, all local men, for the excellent amount of work accomplished."

Jun 1, 1947

By Avis W. Effinger

In conjunction with pilot steamflood tests in the Venango sands of Warren and Venango Counties, Pa., the Marx and Langenheim (4)3 calculations were adapted and programed for digital computer solution to predict test performance. The Monte Carlo technique was incorporated in the calculations to provide values of several variables which could not be adequately defined from available information. The computation methods are explained and the FORTRAN IV program listing is presented. Data and results of the prediction calculations for Venango oil sands are also shown.

Jan 1, 1969

By J. B. Zadra

Much has been published by various investigators on the use of activated carbon for adsorbing precious metals from cyanide solution and pulp. For the benefit of the reader, a list of these earlier publications appears at the end of this report. The present paper deals only with a process for extracting gold from gold-laden carbon and re-use of the de-adsorbed carbon. At the Getchell mine, Redhouse, Nev., experiments have been in progress for several years concerning the use of activated carbon to adsorb gold from their slime circuit pulp. The experimental work has been successful. Their practice has been to ship the gold-laden carbon to a smelter for treatment, which meant the total loss of the carbon in addition to smelter and freight, charges, all of which proved costly and wasteful.

Jan 1, 1950

All of the coal resource in North Dakota is lignite. The lignite fields of North Dakota cover approximately 40 percent of the total area of the state, with reserves estimated to be 9.8 billion tons, two percent of the U.S. base. The first commercial coal mine in North Dakota opened in Morton County in 1873. As the railroads crossed the plains, the demand for coal increased. Coal for fuel was supplied by the state's underground mines. By 1884, North Dakota's lignite production had reached 35,000 tons. North Dakota was among the fist states to shift from underground to large-scale commercial surface coal mining. By 1927,40 percent of the total production was by surface mining, compared to 2 percent for the nation as a whole. By 1959,86 percent of the total production was by surface mining, while the national average was 22 percent. Since 1966, surface mining has been the exclusive coal production method in North Dakota. North Dakota's regulatory program received conditional approval December 15, 1980. Following approval of amendments to the program, it received full approval February 18, 1986. The Abandoned Mine Lands Program was approved December 23,1981.

Jan 1, 1992

Assess the technical feasibility of mining small and/or deeply buried frozen placer deposits from the surface through boreholes.

Jan 1, 1997

In March, the Minister of Mines, Mrs. Judy Erola, released a mineral discussion paper at the annual meeting and convention in Toronto of the Prospectors and Developers Association. Among the mineral objectives discussed was the revitalization of the "junior" mining industry. That industry reportedly has seen its share of total exploration expenditures fall from 50% in 1969 to 10% in 1979. Some sources believe the reason to be the rise of exploration costs and more- restrictive legislation The junior mining industry reportedly was responsible for 40% of all mineral discoveries in the 1969-79 period. CZECHOSLOVAKIA Czechoslovakia expects its capacity for the recovery of gallium metal to increase from 1,650 kilograms to nearly 3,000 kilograms per year by the installation of new recovery equipment at the aluminum plant at Ziar Nad Hronom in Central Slovakia. World production data are not reported, but the United States consumed 8,000 kilograms (estimated) in 1981, of which 5,536 kilograms were imported. Gallium is recovered as a byproduct of the Bayer process for the conversion of bauxite to alumina, and from certain zinc processing wastes. It is used for electronic applications such as light-emitting diodes for visual display panels in calculators, clocks, and other instruments.

Jan 1, 1982

Objective: On-the-job training (OJT) is a common means of training workers. By definition, it seems relatively simple. However, to be effective, training must go beyond the simple process of following an experienced worker around the workplace— sometimes called the "follow Joe" method. NIOSH researchers spoke with human resources personnel, safety and health specialists, supervisors, experienced miners, and new miners and found that OJT was of high interest, but was rarely part of a formal or standardized program. Various training methods have evolved to ensure that a trainee will absorb the information presented rather than simply emulate what the instructor is teaching. These methods have been brought together into a published guide for developing an effective formalized OJT program. The guide (Information Circular (IC) 9479) is called "Coaching Skills for On-the-Job Trainers." It contains materials and suggestions for your company or mine to conduct a 1-day workshop for teaching OJT trainers how to be better coaches to less experienced workers. The guide was created by the NIOSH Pittsburgh Research Laboratory and a safety professional from a private mining company.

Feb 1, 2006

By Arthur C. McFarlan

There are two distinct coal fields in Kentucky-the Eastern field constituting a part of the Appalachian coal region and the Western field constituting the southern part of the Eastern Interior region. The outcrop pattern of the State is dominated by the Cincinnati arch. Coal-bearing Pennsylvanian strata occupy a low structural position on either flank, preserved thereby from erosion, which in the past has removed these same beds, though a much thinner succession, from the crest of the arch. General geological relationships are shown in figures 1 and 2. On April 13, 1750, Dr. Thomas Walker discovered the first coal recorded in Kentucky. He entered the State through Cumberland Gap (Cave Gap) and found coal a few miles north.

Jan 1, 1944

By S. A. Allen

The Eufaula bauxite district of Barbour and Henry Counties in southeast Alabama covers an area approximately 14 miles long, 6 miles wide at the eastern extremity near the Chattahoochee River, and 10 miles wide at the western end near the east fork of the Choctawhatchee River (see figs. 1 and 2). The long axis of this polygon bears a little south of east.

Jan 1, 1949

By B. J. Moore

This publication contains routine analyses and related source data for 547 natural gas samples from 22 States and three foreign countries. Of this total, 340 samples were collected during calendar year 1967. The remaining 207 analyses are of samples collected during previous years, but releases granting, permission to publish the results were not received until 1967. All samples were collected as a part of a continuous survey of the free world for occurrences of helium in natural gas. The Bureau of Mines has conducted this survey in the United States since 1917, and in 1965 it was expanded to include foreign gasfields. The analyses published herein were made by mass spectrometer and a special helium analysis apparatus which are described in Bureau of Mines Bulletins 4863 and 516.4 Nine previous publications have been made to present results of 7,618 gas analyses made by the Bureau of Mines Helium Activity prior to 1967. The first three, Bulletins 486,5 576,6 and 6177 contain analyses and related source data on 5,218 gas samples collected from 1917 through 1960. The other six

Jan 1, 1968

By C. Özgen Karacan

Longwall mining is an underground mining method during which a mechanical shearer progressively mines a large block of coal, called a panel, in an extensive area. During this operation the roof of the coal seam is supported only temporarily with hydraulic supports that protect the workers and the equipment on the coal face. As the coal is extracted, the supports automatically advance and the roof strata cave behind the supports. Caving results in fracturing and relaxation of the overlying strata, which is called "gob." Due its highly fractured nature, gob contains many flow paths for gas migration. Thus, if the overlying strata contain gassy sandstones or sandstone channels, gas shales or thinner coal seams which are not suitable for mining, then the mining-induced changes can cause unexpected or uncontrolled gas migration into the underground workplace. Vertical gob gas ventholes (GGV) are drilled into each longwall panel to capture the methane within the overlying fractured strata before it enters the work environment. Thus, it is important, first to understand the properties of the gas reservoir created by mining disturbances and, second, to optimize the well parameters and placement accordingly. In this paper, the production rate-pressure behaviors of six GGVs drilled over three adjacent panels were analyzed by using conventional multi-rate drawdown analysis techniques. The analyses were performed for infinite acting and pseudo-steady state flow models, which may be applicable during panel mining (DM) and after mining (AM) production periods of GGVs. These phases were analyzed separately since the reservoir properties, due to dynamic subsidence, boundary conditions and gas capacity of the gob reservoir may change between these two stages. The results suggest that conventional well test analysis techniques can be applicable to highly complex gob reservoirs and GGVs to determine parameters such as skin, permeability, radius of investigation, flow efficiency and damage ratio. The insights obtained from well test analyses can be used for a better understanding of the gob and for designing more effective gob gas venthole systems.

Jan 1, 2009

By H. W. Wainwright

.1. The purification pilot plant and the equipment, solution, and gas cycle used for removing hydrogen sulfide and carbon dioxide are described. 2. As sulfur recovery is necessary in any large Fischer-Tropsch plant, pilot-plant runs were made at 300 p.s.i.g. to study the efficiency of tri-ethanolamine solutions in removing selectively hydrogen sulfide from gases containing varying amounts of carbon dioxide. 3. Aqueous solutions of TEA of 20, 30; 35, and 50 percent were investi¬gated. Data indicate that 30 to 35 percent is the optimum concentration if both selectivity and economy are considered. Slightly better selectivity is obtained with the.20 percent solution, but steam consumption is greater owing to the higher solution rates. Results from our pilot plant runs indicate that a 50 percent solution not only produces an acid gas of lower hydrogen sulfide content but also requires high solution rates to effect hydrogen sulfide purification. 4. Data from 37 runs using TEA are presented in tabular form. In addition, the data are correlated and presented in three sets of curves. By using these curves, it is possible to calculate the compositions of the purified and acid gases for various raw gas mixtures. 5. In cooperation with the Southern Natural Gas Co., investigations were carried out at 300 p.s.i.g. on the simultaneous removal of hydrogen sulfide and carbon dioxide, from gases using various concentrations of diethanolamine. 6. Data from 17 runs employing 20, 30, and 40 percent DEA are reported in both tabular and graphic form. 7. A comparison of the data from one DEA run made at 200 p.s.i.g. with those from the runs operating at 30O p.s.i.g. shows float the absorption capacity of the solution, and, hence, the steam requirements per gallon are about the sage for both pressures. .The only real advantage of the higher pressure is the additional volume of gas that can be treated. 8. The quantity of steam needed to reactivate fouled TEA and DEA solutions increased as the reactivator pressure was increased about 1,0 to 1.1 pounds of steam was required for each gallon of circulating solution when the reactivator was operated at 5 p.s.i.g. 9. A curve is included that shows the effect of the hydrogen sulfide con-centration in a lean 35 percent TEA solution on the hydrogen sulfide content of the purified gas and on steam consumption for reactivation. 10. Both TEA and DEA reduced the organic sulfur content of the raw synthesis gas considerably. Analyses of the lean amine solutions showed a gradual build up of sulfur compounds, indicating that the compounds formed by the amines and organic sulfur do not break down under the ordinary operating conditions of the reactivator. 11. Considerable operating difficulty was encountered in the pilot plant owing to foaming of the amine solutions. Laboratory experiments in which the effectiveness of certain antifoam agents was studied showed Alkaterge C to be most promising for the particular conditions studied.

Jan 1, 1952

By Arno C. Fieldner

Six years ago, I addressed the annual meeting of the American Society for Testing Materials on "Fuels of Today and Tomorrow."3/ Since then, our country has been drawn into another great war of veritably global extent, with unprecedented demands on fuels, foods, and materials in general. My purpose in this address is to review the changes in fuel supply and demand since 1937 and to give you my views on the outlook for the future. CONDITIONS IN. 1237 Daring 1936 the United States produced and consumed one-third of the world production of coal, two-thirds of the petroleum, and about 95 percent of the natural gas. Two-thirds of the oil produced in all countries since the discovery well was drilled in 1859 had come from American wells. With the exception of the three depression years 1931, 1932, and 1933, new oil reserves were being discovered since 1924 well in excess of our increasing rate of consumption. Discoveries of natural gas, likewise, were tremendous in volume, and this fuel was being transported to most parts of the country by pipe lines; some of them more than 1,000 miles long. We had all kinds of mineral fuels in abundance and at prices that did not stint anyone in the maximum utilization of the mechanical devices that were being developed on every hand. No one suspected that the time might come in a few years when, gasoline would be doled out to some of us at the rate of 1-1/2 gallons a week or that many of our fuel-oil furnaces would have to be converted to burn coal. Of course, these restrictions are due to unusual war conditions, such as lack of coastwise tanker transportation, unprecedented demand for aviation gasoline, and the shortage of rubber for automotive tires. However, these shortages do call our attention to the vital part of petroleum reserves in our country's future position among nations. Therefore, it is of special interest to review briefly the relations of recent supply and demand with respect to our various mineral fuels.

Jan 1, 1943

By Glan Dale Coe, Will H. Coghill

"INTRODUCTION Characteristics of the mineral products that are to be contrasted herein are net energy consumed in grinding to a definite top limiting size and size distribution of the ground products. Through contrasts of these grinding characteristics this paper to differences in related mineral products and in unlike products. For,example, in anticipation of the data to follow, although Joplin chert and Babeitt taconits are running mates in defying the best crushing machinery, taconite is one of the more docile and Joplin chert one of the most refractory mineral products ordinarily fed to a grinding Routine grinding tests on a great variety of ores and tabulation of the findings have been covered amply by Lennox 4/ and by Maxon 5/ and associates. In contrast to that work, the present paper is a record of random tests made over a long period, and each answered an urgent question at the moment. The work was done at the Southern Experiment Station of the Bureau of Mines, United States Department of the Interior, in cooperation with the University of Alabama. The pressure of war work prevented an organized investigation."

Apr 1, 1943