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By Seth C. Scharfer

"As part of the Bureau of Mines effort to provide thermodynamic data for the advancement of mineral technology, the Gibbs energies of formation of MoS2 (molybdenite) and WS2 (tungsten disulfide) were determined with high-temperature galvanic cells employing stabilized Zr02 (zirconia) as the electro¬lyte. In the temperature range from 867 to 1,209 K, potential measurements were obtained for the cellPt, MoS2 , Mo02 , SO2 = 1 atm // Zr02 // 02 = 0.0112 atm, Pt, with the overall cell reactionMoS2(c) + 3 02(g, 0.0112 atm) = Mo02 (c) + 2 S02(g). (1)These results, combined with the best available values for Gibbs energies of formation (?G°f) of Mo02 (molybdenum dioxide) and SO2 (sulfur dioxide) from the literature, give the standard Gibbs energy of formation of MoS2, ?G°f, for the reactionMo(c) + S2(g) = MoS2(c) (2)?G°f = -96.681 + 43.76 x 10-3T±0.538 kcal/mole, (3)where temperature (T) is expressed in Kelvins.Similar measurements in the temperature range from 872 to 1,210 K were obtained for the cellPt, WS2 , W03 , SO2 = 1 atm // Zr02 // 02 = 0.0114 atm, Pt, with the overall cell reactionWS2(c) + 3.5 02(g, 0.0114 atm) = W03 (c)+ 2 S02(g). (4) Combination of these results with the best available data of ?G°f for W03 (tungsten trioxide) and SO2 from the literature gives the Gibbs energy of formation of WS2 in the temperature range from 872 to 1,210 K for the reactionW(c) + S2(g) = WS2 (c)(5)?G°f = -92.429 + 43.88 x 10-3T ± 0.280 kcal/mole. (6)A third-law analysis yields a standard enthalpy (?H°f) for the reaction298Mo(c) + 2 S(rh) = MoS2(c), (7)?H°f = -67.36±0.60 kcal/mole, (8)298where the standard states are pure crystalline MoS2 / and rhombic sulfur."

Jan 1, 1980

Phosphorus Phase Analysis of Medium-Low-Grade Rare-Earths-Bearing Phosphate Ores

Sep 13, 2010

By R. E. Simpson

Beginning in 1972, fully grouted resin bolts were used in underground mines. An estimated 20 million resin bolts will be installed in 1980 owing to their apparent support improvement in most roof-bolt applications. Inorganic cements were tested to replace the resin at a lower cost while retaining the advantages of a grouted bolt. Although other inorganic materials were considered, all but portland and gypsum cements were rejected for reasons of availability, performance, or cost. Portland and gypsum-type cements were tested by the Bureau of Mines to select a fast-hardening, low-cost material that would anchor a roof bolt adequately to meet safety standards. An alpha-gypsum cement, accelerated with potassium sulfate, was selected as the best material because it had adequate pull strength at a desired set time of less than 5 minutes and was readily available.

Jan 1, 1980

By Venkatesh S. V J, Shubha M, Srilakshmi G

Choosing for the best option of pile foundations to overcome large lateral and uplift loads for the foundations in transmission line towers/offshore environment is still being a concern to achieve the required capacities but also by considering the suitability aspect in the environment. The objective of this paper is to review the methods that have been done for knowing the uplift resistance and lateral resistance of pedestal piles. Investigations by different methods such as experimental studies, numerical and analytical studies have been done by various researchers in order to evaluate the response of a belled pile. These methods are discussed in this paper and the comparison with straight shaft pile based upon the test and analysis. The results indicated that the uplift resistance and lateral resistance were significantly increased with the adoption of belled piles than straight shaft piles.

Sep 1, 2022

By G. K. Wilson

This paper will discuss some of the more important aspects to be considered when selecting pumps for mill discharge, cyclone feed or other severe-duty applications Included will be the selection of the pump based on such factors as particle size, particle distribution, head, flow, temperature and pH Other specifics to be covered: The relationship of impeller speed, head and wear factors as they affect pump performance and wear life; the importance of selecting a pump whose performance curve best suits the application; and how the addition of service factors applied to the actual operating conditions can lead to severe operational problems such as premature wear, pump running out on curve, and exceeding horse power limitations.

Jan 1, 1996

By J. W. Jensen

This report was prepared as a background reference for future publica¬tions concerning the damping capacity of metals and alloys. It contains a broad description of the theory and methods of measuring damping capacity and correlates the developments of the past decade in terminology, units, and techniques. Damping-capacity instrumentation at the Mississippi Valley Experiment Station, Rolla, Mo., is described. The bibliography contains over 150 references to recent articles, each tabulated as to material investigated and test variables, such as frequency, stress, mode of vibration, and temperature. INTRODUCTION After it discovered high-damping manganese-copper alloys before World War II, the Bureau of Mines began research on the damping capacity of alloys and has continued to expand this activity to the present time. In physical metallurgy, damping capacity has become an important research tool in the Bureau. The physical measurement of the damping properties of alloys was begun at the College Park laboratories, and later conducted at Salt Lake City under the direction of Dr. E. V. Potter. Among the many articles resulting from this work, Damping Capacity of Metals (108)3/ has received frequent men¬tion in more recent literature and describes briefly the methods of measurement employed at that time.

Jan 1, 1959

By William Mayrsohn

INTRODUCTION The net smelter return (NSR) calculations made on various smelter-refiner alternatives, is usually done by taking the gross metal value less metal deductions, smelter-refiner charges and transportation-insurance costs. An important further step in the calculations is the financial charges imputed by refining time, transportation delays, to the time gold is returned (if tolled) or paid for if bought by the refiner. Metal that is priced in advance of payment also requires a forward premium that the mine may or may not be getting. This is a hidden cost that is often omitted from the calculations. Segmentation of each of the above costs are vital to see where improvements can be made through negotiations, better choice of metal pricing or transportation alternatives. BASIC NSR CALCULATIONS SMELTER-REFINER CHARGES Payable Metals - Treatment Refining Charges: Since these can vary from one smelter to another, the effect of a $25 per ounce price increase/decrease should be calculated and kept in mind. This effect is compared to differences in refining/treatment charge and a total smelter/refiner cost on a cost per ounce of dore, gold, or a dry ton of concentrate. Transportation - Insurance: Research has to be done on transportation alternatives perhaps with some assistance from the smelters, railroads or trucking companies. For dore, the U.S. postal service is viable and inexpensive. For railroads, deal with the regional office ie., B&N El Paso, if production warrants regular bulk shipments. Spot rates tend to be higher. A small mine producing concentrates usually goes to the nearest smelter due to extremely high transportation costs. Here is where a refiner can help. Insurance-Quotes for rates on dore/ concentrates are easily obtainable, but the mine has to shop for the best rates. Your insurance broker is the best source of this information. Differences between Mine and Smelter/Refiners Metal losses can be caused by the following: - Concentrate dry weight differences caused by moisture determination or faulty scales (often at the mine). - Sample bias by poor preparation practices on either side ie., grinding of the sample removing gold; or a poorly mixed concentrate. Dore bullion has no such difficulties.

Jan 1, 1987

By Charles Legrand

The problem of mine pumping is so much affected by local conditions, and those conditions are so liable to changes during the life of a mine, that the best system to use is difficult to determine. The experience of the writer has been that, in general, for copper mines, electric pumping is most satisfactory unless the quantity of water to be pumped is great or the mine does not use electric power for any other purpose. As a rule, however, figuring on the cost of necessary power plant, the total cost of installation is greater with electric pumps than steam pumps. As the water is liable to be gritty, outside-packed plunger pumps are to be recommended, and if the water is not acid, or only slightly so, chilled cast-iron plungers pay for their extra cost very quickly in diminished cost of packing. With chilled plungers it is possible to use metallic packing instead of soft packing, if the water is not too gritty or the lift too high. In vertical pumps this packing is satisfactory for lifts up to 400 ft., in the experience of the writer, and may be found satisfactory for higher lifts. For water slightly acid, cement-lined pump bodies have given good satisfaction. For acid water, both plungers and puhp bodies should be made of acid-resisting bronze. For high lifts, especially with gritty water, a satisfactory pump valve is difficult to find. To reduce the unbalanced pressure on the valve at time of opening it is advisable to have narrow seats; this, however, brings high pressures on the seats when the valve is closed. On large valves for lifts of 600 to 1,000 ft. we have used leather, hard rubber, vulcanized fiber, and soft brass; for clear water the latter has given best satisfaction. The difficulties due to grit make it advisable to have large sumps where water can settle, and if possible, to have two of them so that they can be cleaned alternately. At the mines of the Old Dominion Copper Mining & Smelting Co., Globe, it was found that a small air ejector discharging into a mine car provides a very convenient way to clean mud and sand from a sump.

Jan 1, 1916

By Robert Craig, Earl L. Rau

Introduction Grinding circuits are used to reduce the particle size of ores to the size desired for beneficiation or to grind a concentrate to a size required for final marketing. Grinding and classification can be carried out using either wet or dry circuits. Most sulfide ores are ground in wet circuits using one or more stages of grinding to obtain the necessary mineral liberation to produce a final concentrate which will meet the desired criteria. Iron ores are ground in circuits applicable to the particular ore using either wet or dry grinding. Nonmetallic minerals frequently present different requirements. Barite is likely to be subjected to wet grinding before beneficiating the ore; the concentrate is dried and then dry ground to meet market particle size requirements. The one thing that most mill operators will agree to is that there is no such thing as the "best" configuration of equipment for grinding. The circuit which works well on one ore may be totally unsatisfactory for another ore body. The general trend in the industry is flow sheet simplication with fewer parallel circuits instead of multiple-line circuits using small mills. This change in philosophy has been brought about by the saving of both capital and operating costs that may be possible with larger equipment. Remember that comminution is basically a very inefficient process, and that the costs can range upwards to 50% of the total milling costs. It, therefore, behooves the mill operator to carefully design his grinding and classification circuits. He must ascertain the optimal economic particle size for beneficiation and then make certain he has achieved the best balance between capital and operating costs to achieve the desired mesh of grind. Equipment Grinding circuits consist of one or more pieces of equipment to grind the solids. Generally, these circuits include one or more grinding mills, classification equipment, and the necessary materials handling equipment such as pumps, pipelines, and conveyors. There are many different types of equipment available which are used to grind and classify ores and minerals. Following is a tabulation of most of the equipment used for wet and/or dry grinding.

Jan 1, 1982

By W. M. Jr. Aubrey, R. L. Stone

INTRODUCTION Most metallic minerals and some industrial minerals have a relatively high specific gravity and most have at one time or another been concentrated by gravity methods. The principles of gravity concentration are straightforward, well documented and easy to understand, but in practice there are many pitfalls that await the engineer in the development of an integrated flowsheet. Gravity concentration equipment has a long history of use and there is a great diversity available. The equipment is capable of treating material over a broad size range, only falling off in efficiency in the very fine sizes. Gravity concentration is also inexpensive, generally free of environmental problems, and commercial equipment can process large tonnages of ore with a minimum of capital cost. As might be expected of an efficient and low cost process, the bulk of the tonnage quickly and inexpensively. Another obvious application is treating mineral deposits such as hematite and manganese ores that are sufficiently liberated after a minimum of crushing to allow production of a coarse concentrate that will meet market specifications. Except for hand picking and mechanical sorting, there is no competing process on coarse size material. Conversely, it is sometimes obvious that gravity concentration does not warrant consideration. Examples are ores that require very fine grinding to attain liberation, for ores where the minerals of interest have a gravity similar to the gangue, and ores that are strongly magnetic. Actually a mineral processing engineer may not know if gravity is the best way to concentrate an ore, but he should have little difficulty recognizing when gravity concentration deserves consideration based upon specific gravity differences and liberation gravity concentration has wide use. size. His challenge then is to At times its selection as the identify and test the applicable primary concentration process is processes, to develop a obvious. Low grade placer deposits metallurgical balance and flowsheet of tin, gold and beach sands usually for the best process, to estimate are only profitable because gravity production rate over the life of concentration is able to throw away the deposit and to make equipment

Jan 1, 1986

By Zengjie Wang

Kinetic study of hydrochloric acid leaching of Panzhihua ilmenite from China is presented. Both temperature and concentration of hydrochloric acid have significant effects on the rate process of Fe dissolution from ilmenite ore, while the ratio of liquid to solid has little effect on the Fe dissolution. The Fe dissolution is found to follow the spherical model f (??) =1-(1- ??)1/3 and the apparent activation energy is calculated as 47.21 KJ/mol, suggesting a chemical reaction controlled mechanism. The dissolving behaviors vary at different kinetic stages. At the beginning the amount of the dissolved Fe and Ti increased monotonically with leaching time, while about 15 minutes later the dissolved Ti in the form of TiOCl2 began hydrolyzed into TiO2 fines reunited on the ilmenite ore surface, as observed by SEM and EDS technique. For the unreacted ilmenite particles covered by a layer of hydrolyzed TiO2, the leaching seemed to be as a selective leaching of iron and because Ti dissolved from and hydrolyzed rapidly again into the unreacted ilmenite particles. The leaching process can be ended 4 hour later when almost of Fe has dissolved into the solution and TiO2 remains as solid residues. The effects of acid concentration and leaching temperature were also investigated.

Jan 1, 2009

By Cliff Holloway

The past year has been difficult for Canada's primary industries. The mining, oil and forestry industries have been hit by low prices and a reduced demand for natural resources. Foreign competition, militant environmentalists, the breakdown of the Asian and European economies and Canada's shrinking dollar have all put additional pressures on the commodity purchaser to buy smarter. It is easy to appreciate why operations and maintenance supervisors want the best performing product. It makes good sense. The challenge is to source that quality product while staying within the budget. The bottom line (price), however, often becomes the control- ling factor, usually at the expense of quality and performance. This is short-term thinking, often with expensive consequences.

Jan 1, 1999

By Juliano Braz Possatti, José Fagundes Júnior

This project involved a teamwork including process control, maintenance and operation specialists, R&D and CTO experts to identify and actuate on each opportunity to increase charging temperature, furnace efficiency, decrease discharging temperature when possible, decrease FM and RM cycle time (mainly speed increase and interpass time decrease), tracking zones optimization, safe use of equipment power limits, safety interlocks revision and tune models for Mill Pacing Control and Slab Design.As result of these efforts, ArcelorMittal Tubarão HSM today occupies a prominent position among the best HSM of similar layout and produced mix of the group and worldwide. This paper will show the path which was followed by the AMT HSM team to achieve more than a 20% productivity increase resulting in a hot coils production per year more than 700 million tons higher.

Oct 1, 2019

By J. A. Finch, R. R. Cunningham

The amount of foam volume generated in relation to the gas flowrate has long been used to define the foaminess of a solution and to characterize surfactants. The vessel geometry and gas flowrate range can affect the foam volume results. A fixed area column was tested alongside a variable area conical vessel with two surfactants. It was found that the fixed area vessel will cause foam volume to expand or contract which masks the effect of the surfactant. The conical vessel showed two regimes of foam volume production dependant on gas flowrate. The low gas flowrate regime revealed the physiochemical nature of the surfactant while a high gas flowrate revealed kinematic properties. Foaming properties of a surfactant is best determined with a variable area vessel at low gas flowrate.

Jan 1, 2009

By W. L. Zhong

Probability function integration method is one of the influence function method. It is a widely accepted method in many mining districts in China and Poland mainly because its theory and formulae can well-represent the surface subsidence basins due to longwall mining of flat or near-flat seams. This paper introduces the basic theory of the probability function integration method and determines its 4 basic parameters by analyzing the measured subsidence profiles in eight longwall panels in Northern Appalachian Coal field. It also discusses the two methods for determining the 4 parameters. Finally the acquired parameters are used to predict the subsidence and deformation of the houses for damage assessment. Comparisons are made between the measured and the predicted subsidence. Probability Function Integration Method The probability function integration method for predicting surface movements and deformations is widely used in China and Poland. The governing equation of the method contains five parameters: subsidence factor, a, offset of inflection point, d, tangent of the major influence angle, tan fl, horizontal movement constant, b, and major dispersion angle e (e = 90. for flat seams). Its applicable range iis much larger including seams less than 30' from the horizontal, critical and noncritical mining and soft to hard overburden.

Jan 1, 1986

By T. Lenarcic, R. Svrkota, J. M. McNeal, E. Prohic, S. Pirc

Paper presented at the 28th International Geological Congress held in Washington DC, July 1989 (International geochemical mapping sessions). Surface drainage samples, the usual media employed in mapping national territories, cannot be used for the geochemical mapping of carbonate terrains because there is no regular surface-drainage pattern on karst. Suitable sampling media have been studied in Yugoslavia, one-third of which consists of karst terrain. Sampling designs for the work were based on analysis of variance techniques. During initial investigations of various sampling materials in NW Yugoslavia sediment and aquatic moss from karst springs, along with soil, were established as the most appropriate media. Modified sampling procedures were then carefully applied along the entire Yugoslav karst belt, which includes terrains of contrasting topography, climate, pedology and vegetation. The studies indicate that climate and relief do not systematically influence the geochemical composition of soil. Regional and local variability was assessed for 21 chemical elements and the feasibility of producing stable regional geochemical maps was determined for a number of elements on the basis of sampling aquatic moss and sediment from karst springs and soil

Jul 1, 1991

By B. W. Gandrud

This is the third report published by the Bureau of Mines concerning the washability of Black Creek coal. Both of the former reports5/6/ dealt with the Black Creek coal at the Bradford mine, Dixiana, Ala., near the northeastern extremity of the Warrior field, whereas the present report is based on float-and-sink tests of coal from what is presumably the Black Creek bed near the southern extremity of the field. Although the Yolande Coal & Coke Co., owners of the property at Yolanda No. 6 slope, consider this opening to be on the Black Creek bed, the authors do not feel that there is as yet positive proof that this correlation is correct. There has been little or no development of the Black Creek bed in the Yolande Basin in the past, and a posy-tine identification of the bed at Yolande No. o will have to await further exploration and development. The Yolande No. 6 is an exploration slope 3/4 mile north of Rockcastle, Ala. The slope is approximately 400 feet from top to bottom on a dip of 18° As fax as the authors can ascertain, coal has never been produced commercially from the Black Creek bed in the southwestern part of the Warrior field. Exploration work in the past has indicated that the Black Creek coal in. this area is extremely friable and high in sulfur. Extreme friability would naturally discourage its' use as a domestic and railroad fuel, and high sulfur content would be a disasvantage in its use for coking coal. The present study of this coal has been made with particular reference to sulfur elimination on the assumption that it would make a good coking coal provided enough of the sulfur could be eliminated by washing.

Jan 1, 1939

By B. W. Gandrud

This is the third report published by the Bureau of Mines concerning the washability of Black Creek coal. Both of the former reports.5/6/ dealt with the Black Creek coal at the Bradford mine, Dixiana, Ala., near the northeastern extremity of the Warrior field, whereas the present report is based on float-and-sink tests of coal from what is presumably the Black Creek bed near the southern extremity of the field. Although the Yolande Coal & Coke Co., owners of the property at Yolande No. 6 slope, consider this opening to be on the Black Creek bed, the authors do not feel that there is as yet positive proof that this correlation is correct. There has been little or no development of the Black Creek bed in the Yolande Basin in the past, and a positive identification of the bed at Yolande No. 6 will have to await further exploration and development. The Yolande No. 6 is an exploration slope 3/4 mile north of Rockcastle, Ala. The slope is approximately 400 feet from top to bottom on a dip of 180. As far as the authors can ascertain, coal has never been produced commercially from the Black Creek bed in the southwestern part of the Warrior field. Exploration work in the past has indicated that the Black Creek coal in this area is extremely friable and high in sulfur. Extreme friability would naturally discourage its use as a domestic and railroad fuel, and high sulfur content would be a disasvantage in its use for coking coal. The present study of this coal has been made with particular reference to sulfur elimination on the assumption that it would make a good coking coal provided enough of the sulfur could be eliminated by washing.

Jan 1, 1939

By M. Bustillo, S. Ordonez

"Paper presented at the conference Economic geology in Europe and beyond II, models for mineral deposits in sedimentary basins, held in Keyworth, UK, 13-14 April 1994. The Mississippi Valley-type deposits occur in massive, homogeneous dolostones from which diagenesis has obliterated all primary sedimentary structures. The mineralisation forms irregular, lens-shaped stratabound bodies, mostly in the lower part of the dolostones. They are composed exclusively of sphalerite, galena, pyrite, marcasite and barite, with white sparry dolomite a common cementing phase. Mineral zoning can be recognised from pyrite and marcasite in the east to barite in the west. Sphalerite, the most common sulphide, occurs basically as colloform and banded crusts and galena as isolated cubic or skeletal crystals, mainly in the centre of the banded botryoidal sphalerite. The combined observations of the deposits' geology, geochemistry and ore petrology suggest a three-stage genetic model: carbonate sedimentation in a shallow-water environment; dolomitisation, probably after compaction, by fluids of connate origin and lateral evolution; and mineralisation by migrating solutions, perhaps related to oil-field brines, that originated in deep zones of the basin during diagenesis of the basinal mudrocks in the NE"

Apr 1, 1995

ONE DAY IN the mid-1880s, in a suburb 0f Pittsburgh, Pennsylvania, there dismounted from a train the two foremost leaders of the day in the coal and steel industries-Andrew Carnegie and H. C. Frick. Their attention was drawn to a well-loaded car of coke, which their experienced eyes recognized as a superior product. "I'll bet you that coke is from the H. C. Frick Coke Company," Mr. Frick challenged. "I'll bet it was shipped by my company." In a spirit of fun Mr. Carnegie accepted the wager. Mr. Frick lost the bet: the coke had come from M0rewood, one of three sites being operated under the direction of a young entrepreneur, Erskine Ramsay. If Mr. Frick's confidence was somewhat dented by this occurrence, the responsibility was his own. He himself had opened the way for Erskine Ramsay to become the youngest of mine superintendents; and he had dispersed all dissension regarding his choice with the words : "I'm not interested in his years, I'm interested in his record. He makes more coke in an oven than any other superintendent. And I'll take 'em out 0f the cradle if they can make coke... Suppose he is only twenty years old? ... The d --- kid is a genius, I tell you." Erskine Ramsay was to follow in the tradition of Carnegie and Frick. Not only was he ambitious and a worker his background had prepared him for it. Coal mining was in the Ramsay blood. His father, Robert Ramsay, of whom the son once stated that he had no superior as coal mining and mechanical engineer in this country, once accounted in these words for the phenomenal accomplishments which had attached to the name "It does no harm to belong to a family of mining engineers who are just as good as any in America-if it is myself that says it." Anyone acquainted with Robert Ramsay's character realized that he was not given to overstatement. And the above-mentioned Mr. Carnegie encountered young Ramsay again, a few years later in his career, and wrote of him to young Erskine's father, that he was "going to be a credit `tae us a' " (a quotation from Robert Burns.) Nor have Mr. Ramsay's achievements been identified exclusively with the industrial field in which he early asserted himself. He has been an inventor whose techniques in mining engineering have received international recognition. As an investor of foresight, he has benefitted others immeasurably, as well as himself, being an influential factor in the upbuilding of several communities in his chosen and well-loved adopted home state of Alabama since 1887. He is a philanthropist whose benefactions have run into millions, the chief beneficiaries being educational and charitable institutions. Amidst his accomplishments the lighter side of life has not been neglected and he is known for his hospitality, his

Jan 1, 1953