Search Documents

By F. Sillers, R. T. C. Rasmussen

"INTRODUCTION This is the fourth report of investigations dealing with the cooperative tests between the Bureau of Mines and industry on the use of electrolytic manganese in steelmaking. The first report dealt with the use of electrolytic manganese in the manufacture of stainless steel 3/ the second with its use in acid electric steel practice, 4/ and the third with its use in low-carbon basic open-hearth steelmaking. 2/ A résumé of those investigations E7 appeared in the magazine STEEL. 5/ The present report deals with the use of electrolytic manganese in the manufacture of four types of stainless steel and the new Timken 16-25-6 alloy. The Bureau of Mines supplied The Timken Roller Bearing Co. with 62,000 pounds of electrolytic manganese for use in the tests.The electrolytic manganese was produced at the Bureau of Mines pilot plant, Boulder City, Nev., by the process developed by the Bureau and described in Bulletin 463, Operation of Electrolytic Manganese Pilot Plant, Boulder City, Nev., by J. H. Jacobs. J. W. Hunter, W. H. Yarroll, P. E. Churchward, R. G. Knickerbocker, R. W. Lewis, H.A. Heller, and J. H. Linck. The workcarried out under the direction of R. S. Dean, formerly assistant director, Bureau of Mines, and R. G. Knickerbocker, formerly chief, metallurgical branch, as part of a long-range program involving the development, manufacture, and use of manganese from domestic ores. Preliminary arrangements for the plant tests were made by the late A. A. Dow. 7/"

Jun 1, 1947

By Robert L. Lagace

[Suuple Iheorctrccil models are I'M lllolalcd to cltaraclerl/c medium frequency (MF) radio vase pi opaiation in undcrgiounli room arid pillar coal mines fur the purpose of predleiln the most lavolable operating fIegtucncics,md nr,ixunum communic;IIIoil ranges for pottahIe rldu)s with I top antennas. I or conductul IrCC areas, at hree layer propaeaIion IltodcI wit II a Iiallsmissloil IIIIi- lhlllllIIal'u11 lot the plupa!edti ii unlstallt Iris been dcvcloped ;md verified experimentally. 1 lie mode u1 propaCaUetl lakes Ills form of i parallel plane (0,t)) TIM lransnussu)nhne 1% PC of mode with the electric held vertical and the magnetic held hoti/cntal t itliin a planar coal scam in which the tunnels Can he ignored and which 1s hounded above and below hp richer conductivity rock. 1lie model lilt the data best river the 200 io 1000 kH/ frequency hand and exhibits a rc;;lon of optlnrul1l Pelffelntance, with respect Io maxnluiulg radio Communication range, between 300 and 100 klf/. Maximum cunununlcatrorl ranges are sliongls dependent oil the sigiial alleilliatroil sale, ant) Illelclulc on the electrical conductivltles of the coal seam and surrounding ruck. These ranges v;ny tutu about ,,5 Io 100 nleleis Ill a high Iuss scam such as the Ilelllit No. fl to about .100 to 400 meters in a low loss seam such as the Pittsburgh foil portable intrinsically safe radios. The ieslllls die haled on the comparison oftheorc' and experiment for eleven n n. ill sesen coal seams. V OT ate is dice: a conductor such as a power Cable, is present a model has been developed for the coupling of loop antennas to a low loss Coaxial TEM ti;u?smisslon line mode in which the cable acts as the inner conducl,lr and the rock above and below acts as the outer conductor. The electuc and md' nctic Itelds for till` (node are apprlixitllatcly transverse to the cahlC and fall oil expontially with distance in the transverse plane. The principle of reciprocity is used to simplify the analysis. More expelitnental data arc needed to help resolve discrepancies between the theory and the limited data available to date.]

Jan 1, 1980

By U. A. Peuker, T. Mütze, F. Shayo, A. Wikedzi

"Buzwagi Gold Mine (BGM) is operated by Acacia Mining and located in the Lake Victoria Goldfields of central Tanzania. The mine treats a sulphide copper-gold ore to produce gold in form of doré bars and a concentrate containing gold, copper and silver. The BGM comminution circuit includes a primary crushing stage with a gyratory crusher and two grinding circuits using a Semi-Autogenous Grinding (SAG) mill and a ball mill. Currently, the grinding circuits are inefficient in achieving the aspired product fineness of xP,80 = 125 µm even at low to normal throughputs (450-600 t/h). An optimization study of the circuit performance was conducted to improve product fineness through circuit surveys, experimental lab work and simulations. The analysis of survey data revealed inefficient grinding operation characterized by ball mill product (xP,80 > 400 µm) coarser than designed and higher hydrocyclone cut sizes (xT > 200 µm), too. In MODSIM several options were simulated such as reduction of vortex finder and apex diameters, reduction of SAG screen aperture, and modification of cyclone feed density. An improvement of product fineness could be achieved by simulation of the cumulative changes but it was also concluded that the current equipment cannot achieve the target. Further simulations showed that a second ball mill might help to achieve the desired fineness as well as an increase of grinding throughput by up to 26 %. INTRODUCTION Simulation of comminution, particularly grinding and classification, has received great attention for many years, due to the fact that the unit operation is by far the most important both in terms of energy consumption as well as overall plant performance (King, 2001; Wills et al., 2006). The use of simulation is advantageous due to low cost as well as its ability to consider many variables simultaneously. Moreover, there are some benefits for optimizing grinding operations by simulation like decreased unit operating costs, increased capacity, and improved performance of downstream processes due to improved feed size distribution. This paper presents an optimization study for the grinding efficiency at Buzwagi Gold Mine. This was achieved through three full scale circuit surveys, lab work and simulations with MODSIM."

Jan 1, 2018

By I. J. Duckworth

During the last twenty years computers have be-come widely used to assist with the simulation and design of large scale, primary ventilation systems. However, to date there are few computer programs available to help with the modeling of auxiliary ventilation in dead-end headings or tunnels. This paper presents the results of the first year of a research and programming study dedicated to the development of a user-friendly duct simulation tool. Included is a literature review that summarises publications on duct leakage and resistance, on previous programs developed for the simulation of airflow in ducts, and case studies on extended ductlines in mines and tunnels. The methodology behind the development of Ductsim, a Windows based simulation program is presented.

Jan 1, 2000

By M. A. Rabah

This paper focuses on the separation and extraction of lead and zinc from Egyptian ore at the Eastern Desert close to Red Sea. The ore sample contains cerussite, galena, hemimorphite and other impurities. Experimental program includes flotationof galena using xanthate collector and cerussite using oleic acid as collector and sodium silicate to depress hemimorphite tailing. Galena, and hemi-morphite are converted to carbonate with sodium carbonate prior to metal extraction. Lead and zinc are extracted pyrometallurgically at 1050°C and750°C or electrochemically respectively. The overall performance of the applied method amounts to 99.2%. Extraction efficiency of lead and zinc amounts to 98% and 94.5 % respectively. A model assumed that galena and cerussite in the ore are partially oxidized and can be liberated by grinding. Oleic acid selectively reacts with cerussite in a multistep sequence. Preliminary cost estimate shows that the price of the products is competitive to their local market prices.

Jan 1, 2000

By A. W. Fahrenwald

"The rate of progress in the last three years in the development of differential flotation has been rapid beyond the realization of most people. Differential flotation is no longer a ""delicate"" and unreliable process, but is now in wide use. Its ""safety"" is due to the wide use of chemicals which either depress or enhance floatability by definite modification of surfaces.The extent of the development and reliability of differential flotation methods any be emphasized by pointing out that there are now several customall-flotation"" plants in this country treating complex lead-zinc-iron ores from widely separated mines. While these ores differ in chemical composition and apparently in physical nature, the various ores treated in such a plant are passed through the same crushing and grinding equipment and through the same flotation machines and flow sheet with only slight changes, if any, in quantity and kind of chemicals and oils added.Some of the development in differential flotation is due to intelligent research on the part of well-trained chemists and metallurgists; much of It must be attributed to empirical testing.Much of the success in differential flotation is due to more care being given to constant conditions with regard to such factors as (1) fineness of grinding, (2) density of pulp entering flotation machines, (3) quantity and constancy of oils and chemicals added to the pulp, and (4) place of addition of reagents, and time of ""conditioning"" treatment of pulp with reagents."

Aug 1, 1925

By Steven K. Ruggieri

This report describes the operation and maintenance of the Mobile Inert Gas Generator for use in the Remote Sealing System for fighting underground coal mine fires. Seals are emplaced in mine passageways between the fire zone and the rest of the mine isolating the fire zone from the mine. The seals consist of fly ash that has been pneumatically conveyed via inert gas through a borehole connecting the surface and the passageway, Inert gas is used as the fly ash seal transport medium (instead of fresh air) since the introduction of large volumes of fresh air in the vicinity of the fire zone would be undesirable. The inert gas generation equipment is mounted on two flatbed trailers, the "hot" trailer and the "cold" trailer. The hot trailer contains the combustion and cooling equipment. The cold trailer contains the moisture removal and compression equipment necessary to convey the fly ash. The system is self-sufficient and requires only fuel and fly ash deliveries. The Inert Gas Generator has been thoroughly performance tested and has been operated in the field for approximately 200 hr. The system was employed in the demonstration of the entire Remote Mine Sealing System at the Jenney Mine in the Fall of 1978. The system is currently available for fighting any future underground coal mine fires.

Jan 1, 1980

By E. A. Clarke

The vapor-phase section of the Coal Hydrogenation Demonstration Plant at Louisiana, Mo., was operated for the first time in April 1949. The run lasted only 10 days because of time limitation (pending plant dedication in May) and the small amount of charging stock available. The primary purpose of the operation was to break in and determine the operability of the equipment and to supplement the operators' classroom training with actual practice by operating the plant under mild conditions. A secondary aim was to obtain data on the hydrogenation of petroleum oil and lignite tar distillate at approximately 10,000 p.s.i. while making gasoline and Diesel fuel oil. Although the operations were carried out under conditions considerably below those used in the plant design, a great deal of experience and data was obtained. As it is not feasible at this time to conduct further vapor-phase operations on similar stocks, this report has been prepared to present and summarize the data obtained through this operation.

Jan 1, 1950

By T. F. Myners

This paper, describing the concentration methods and costs of Witherbee, Sherman and Company at Mineville, N. Y., is one of the series of papers on milling methods and costs being prepared by the United States Bureau of Mines. It deals principally with the production of high-grade concentrate. ACKNOWLEDGMENT The author is indebted to C. F. Jackson, principal mining engineer, United States Bureau of Mines, to A. M. Cummings, general superintendent of Witherbee, Sherman and Company, and to the company's engineering staff, for assistance in preparing this paper.

Jan 1, 1932

Jan 1, 1957

By Yang Ge, Yuzhu Pan, Mansheng Chu, Jue Tang, Cong Feng, Lihua Gao, Zhenggen Liu

The low-grade nickel laterite ore used in this study was successfully upgraded through selective reduction by industrialized rotary kilns followed by magnetic separation. The results indicated that both iron metallization extent and nickel metallization extent showed obvious linear correlation. In addition, rational roasting temperature and prolonged grinding time could enhance the overall fineness level of reduced laterite nickel ore. The moderate roasting temperature at a range of 1100–1150 °C should be suitable enough to a conversion of total nickel to metallic nickel and partly inhibited the conversion of total iron. Ultimately, the obtained ferronickel alloy with a nickel content of 7.32% and an iron content of 84.15% was prepared successfully from the lowgrade nickel laterite ore containing a nickel content of 1.92%. Nickel and iron recoveries were 96.72 and 89.08% respectively, which achieved the highly efficient recovery and utilization of iron and nickel from low-grade laterite nickel ore

By Arthur W. T. Grimley

Hydraulic coal mining is being successfully practiced in China, U.S.S.R., Japan and Canada and in each country, excepting Japan where suitable sites are not available, the system is being expanded to either existing conventional mines or new mines. Productivity levels and economics at these mines are in all cases better than the productivities achieved in conventional mines in the same general localities. In the U.S.S.R. face productivities approaching 50 tons per man shift have been reported while in Canada the latest statistics show average face area productivity levels are in the region of 200 tons per man shift production monitor. In the United States hydraulic mining has not been actively pursued to the same degree and consequently there are no full scale hydraulic coal mines in operation or construction. Because many of the coal measures in the Western U.S.A. are generally somewhat similar to those being successfully hydraulic mined in Western Canada and parts of Siberia it is realistic to believe that successful hydraulic mines can be designed and developed in the Western U.S.A. Particularly if the vast technological base that already exists is used to improve on other people's ideas, systems, methods and equipment.

Jan 1, 1983

By Sandra Lúcia de Moraes

O presente trabalho visou contribuir para o melhor entendimento do mecanismo inerente ao uso de agente coloidisante/dispersante no processo de pelotização de concentrado de minério de ferro. Avaliou-se a influência dos agentes coloidisantes em comparação aos aglomerantes Peridur e bentonita. Para este fim, foram realizados ensaios de bancada visando a identificação de possíveis ações destes agentes no grau de dispersão das misturas, bem como a sua influência na liberação/aglomeração dos finos. Os resultados destes parâmetros foram confrontados com os resultados de caracterização das pelotas confeccionadas com os diferentes agentes pelos quais foi possível identificar que os dispersantes tem forte atuação sobre o conteúdo de finos do concentrado de minério de ferro. A ação principal se dá pela remoção das partículas ultrafinas que recobrem os grãos mais grosseiros presentes na amostra e as dispersam, no caso dos dispersantes, aumentando a disponibilidade do conteúdo de finos <4 µm, principalmente os finos <1 µm (coloides). No caso do aglomerante orgânico, observa-se também essa ação, no entanto, os finos presentes são aglomerados na faixa entre 26 e 4 µm.

Aug 16, 2017

By Paul D. Tomlingson

World class performance is the ultimate objective of many maintenance organizations. It marks the organization as a leader in its industry and sets it apart as the ultimate achiever. But what is a “world class” standard and how can it be achieved? Is there a yardstick by which an industrial organization can measure the relative performance of its maintenance activity and compare it with performance levels that universally identify “world class” status? Are there financial formulas, achievements, evaluation techniques or indices that provide this yardstick?

Jan 1, 2006

By M. F. Koehler

[THE LITERATURE contains relatively few thermodynamic values for interoxidic compounds, and these often are unreliable. This is especially true of data for ferrites and aluminates for which heat of formation determinations may involve extreme experimental difficulties. This report contains the results of new experimental work for obtaining the heats of formation of five ferrites (Ca2Fe2O5, CaFe2O4, MgFe2O4,, NaFeO2, and LiFeO2) and one aluminate (CaAl4O7), and a review and revision of previous similar work of this laboratory on five aluminates (Ca3A12O6,, 12/7 CaO-Al2O3, CaAl2O4, NaA1O2, and LiAlO2), The results for the 11 compounds are combined with entropy and high-temperature heat content data to derive tables of heats and free energies of formation (both from the oxides and from the elements) for the temperature range 298° 1,800° K, The relative stabilities of the compounds are discussed. The presented data all have application to ceramic reactions, and those for the calcium and sodium aluminates are applicable in considering soda-lime sintering processes for extracting alumina from silicate minerals such as day and labradorite.]

Jan 1, 1961

By Albert L. Toenges

This paper is the fourth of a series5/ that describes some methods and practices of mining coal mechanically where operations are conducted on more than one shift. Many inquiries have been received regarding methods of extracting pillars with mechanized equipment, and this paper deals primarily with this phase of mechanical mining. Some of the questions that have been asked are:

Jan 1, 1942

By Carl Heinrich

I HAVE read with particular interest that portion of the discussion by Anton Eilers referring to the high-lime (and also high-alumina) slags made by August Raht in 1881, while smelting the Horn Silver ores at Franklin, Utah. The two analyses of such slags, furnished by Mr. Raht to Mr. Eilers are: Horn Silver Slags Oxygen(b) Oxygen(b) Average of I and. II Slag I percentage Slag II percentage Oxygen Si02 33.9 18.1 .35.0 18.7 34.50 18.40 FeO 26.8 6.0 25.4 5.7 26.10 5.80 CaO 26.1 7.5 24.9 7.1 25.50 7.30 BaO 3.2 (a) 0.3 3.2 0.3 3.20 0.30 A1203 10.8 5.1 9.3 4.4. 10.05 4.75 100.8 37.0 97.8 36.2

Jan 10, 1916

By S Jahanshahi, D R. Swinbourne

A knowledge of the value of the activity coefficient of cobalt oxide in slag as a function of composition and temperature is necessary if effective strategies are to be devised to maximise the recovery of cobalt in nonferrous smelting processes. This work reviews previous studies and shows that comparison and evaluation of the results is hampered by variations in the choice of standard states for the species. Published results have been recalculated to a common set of standard states with a preferred value for the Gibbs free energy of formation of cobalt oxide. It has been shown that the value of the activity coefficient of cobalt oxide referred to the solid standard state in iron silicate slags is approximately two, at temperatures from 1523 to 1623¦K. It is suggested that some contradictory results are most likely due to errors in the measured partial pressure of oxygen.

Jan 1, 1998

By E. M. Abraham

The establishment and survival of different grass species and cultivars on various phytotechnic treatments at a limestone quarry was studied. The treatments applied were: a) bare soil, b) bentonite, c) bentonite-straw and d) asphalt-straw. According to the results, significant differences were found among species and cultivars, growing on different treatments as far as plant growth and survival are concerned. The seed germination was higher on bentonite -straw and asphaltic-straw than on bentonite but the plants survival were higher on bentonite. Lolium perenne had higher seed germination rate and better establishment than the other tested species at all treatments. However, the survival rate of Agropyron desertorum and of the cultivars palestina and chrysopigi of Dactylis glomerata was higher than of the other species.

Jan 1, 2007

Objective: Improve the dust control effectiveness of enclosed operator cabs on surface mining equipment.

Oct 1, 2007