Search Documents

By Jue Kou, Hongda Xu, Tichang Sun, Shichao Wu, Wenli Han

To investigate the effect of simultaneous change in particle size of raw materials (including ore, reductant, and dephosphorization agent) on the direct reduction process of high-phosphorus oolitic hematite, the experimental research of method with direct reduction and magnetic separation was conducted to investigate the effect of simultaneous change in particle size of raw materials on the final reduction products in the form of mineral composition, reduction speed, metallic iron particle morphology, phosphorus distribution, and powdery reduction iron. The results revealed that under the same conditions of reduction temperature, the raw material particle size affects the mineral composition of the final reduction product, the coarser the raw material particle size, the slower the reduction speed, the lower the metallization rate, and the larger the final metallic iron particle size formed. Under the same conditions of raw material particle size, the reduction temperature affects the mineral composition of the final reduction product, the higher the reduction temperature, the faster the reduction speed, the higher the metallization rate, and the larger the size of metallic iron particles within a certain reduction time. Neither the raw material particle size nor reduction temperature affects the form of phosphorus present in the reduction product. Both the raw material particle size and reduction temperature affect the grade of powdery reduction iron to a less extent, but affect the recovery rate and phosphorus content significantly. At the same reduction temperature, the recovery of powdery reduction iron and phosphorus content gradually decreases with the increase in raw material particle size. For the same raw material particle size, the recovery of powdery reduction iron gradually increases, and the phosphorus content gradually decreases with the increase in the reduction temperature. The results identified the effect of simultaneous changes in particle size of raw materials on the direct reduction process of high-phosphorus oolitic hematite and provide a basis for the selection of raw material particle size for the industrial application.

Dec 20, 2022

By Kenneth Eilerts

[The development and operation of ?combination on wells?5/ have created new and unusual problems, many of which cast to solved only if information is available concerning the properties of the fluids produced. Data as to the characteristics of the fluids at the relatively high pressures that exist in the reservoirs are especially important, and there is growing economic concern to know what part, if any, of the liquid recovered at the surface was liquid in the reservoir, As an extension of this problem, it is important to Know whether liquid will be formed in the reservoir it as a result o a isothermal retrograde condensation when the reservoir pressure is reduced. The pressure range of such condensation, if it occurs, is significant in the design of gas-recycling plants for maintaining reservoir pressures. In connection with the operation of such plants, it is particularly important to know how gyres sure and temperature will affect the yield of the liquid phase and the composition of the gas to be returned to the reservoir. It has not been possible to predict the behavior of these fluids that have high ratios of gas to liquid by comparing them with the behavior of low gas-liquid ratio fluids at identical pressures and temperatures. Such comparison fails because the proportions in which a component will be distributed between the phases of a system at any given temperature and pressure depend increasingly on the composition of the mixture as the critical temperature and pressure of the oysters are approached. Because many combination wells are producing from reservoirs that have temperatures near the critical point, experimental date on the properties of the fluids under reservoir conditions are particularly important at this time. To rest the immediate requirements of the industry for such experimental information an equilibrium cell has been constructed at the Petroleum Experiment Station of the Bureau of Mines, Bartlesville, Okla. When adequate experimental date, have boon accumulated, it may be possible to mare dependable estimates of the phase relations ft. high gas-liquid ratio fluids at the pre runes and temperatures characteristics of ?combination-well? reservoirs.]

Jan 1, 1940

By Michael J. Beus

This Bureau of Mines report describes field investigations conducted in the Coeur d'Alene mining district of Idaho to obtain data on rock stress and physical properties. The resulting information has been utilized as input to detailed finite-element analyses to establish structural design criteria for deep-vein mine shafts. Measurement techniques include the Council for Scientific and Industrial Research biaxial and triaxial strain cells, the U.S. Geological Survey solid-inclusion probe, and the Colorado School of Mines dilatometer. Physical property testing was conducted in the laboratory on core obtained from each test site. Limited in situ physical property tests were also conducted. Reason-able success was obtained with the CSIR equipment, which was considered the most suitable for stress measurement in the study area. Test sites ranged in depth from 1,200 to 7,700 feet and are described in detail. The stress data were reduced by least-squares linear regression techniques to enable prediction of vertical and horizontal stresses to 7,500 feet. Ratios between the horizontal stresses as utilized for shaft design varied considerably, and a hydrostatic condition is the exception, based on Bureau measurements. Physical properties also varied widely, due to the complex geologic structure. Analyses of the data in terms of the tectonic history of the area show reasonable correlation. Data from previous rock mechanics investigations from the Coeur d'Alene district were also compiled and presented as part of this report to justify any generalizations regarding stress conditions and physical properties of the district as a whole.

Jan 1, 1980

By J. F. Myers

AT the Regional meeting in Columbus, Ohio, in September 1949, the authors presented a progress report of the first year's operation with a Hardinge tricone mill in closed circuit with a Dorr hydroscillator. The present report covers our findings on this grinding circuit to January, 1950. In order to clarify our position, the authors wish to state that no invention or discovery is claimed. The Tennessee grinding circuit is simply an engineered arrangement of known equipment arranged to incorporate all of the recognized efficiency factors of comminution as they are known today. As we concluded our first report, it was not clear how effective the Tennessee mode of operation would be on harder ores. The only information we had at that time was that the Bond grindability test at 48-mesh gave 6.04 g of undersize per revolution. A later test on the same sample at 100-mesh reduced this to 2.04 g, which is definitely in the harder ore class, and which makes the reported 8.80 kw-hr per ton of -200-mesh produced a very creditable figure.

Jan 1, 1950

The recent boom in the mining industry has lead to some unique challenges in successfully operating processing plants. With high turn-over rates of both operators and technical staff, and many experienced personnel leaving regional sites for city based jobs there is often an onsite knowledge vacuum and this in turn puts pressure on both site training departments and senior metallurgists to provide the relevant skills to the continuous stream of new staff. Frequently both operators and new metallurgists are instructed on a æhow-toÆ basis rather than giving them the understanding as to why tasks are performed and decisions are made. This paper has been written with the plant operator and metallurgist in mind and aims to provide suitable material to be incorporated into a site training manual. Topics have been broadly divided into the following categories: factors that operational staff can control; including pulp density, air addition rate, froth depth, particle size and reagent type and use; factors that operational staff cannot control; providing general information on bubble size, froth stability, pulp chemistry and the mechanical effects of the rotor/stator system; and process improvements. Each topic is discussed with a view to clarifying the key process variables that need to be understood and optimised in an industrial operating plant.

Jan 1, 2009

By Mandira Madhuchhanda, N. B. Devi, P. C. Rath, R. K. Paramguru, K. Srinivasa Rao

An experimental investigation of the dissolution of three base-metal sulfide minerals, namely, CuFeS2, ZnS and PbS, in hydrochloric acid medium in the presence of manganese dioxide is reported. Polarization measurements and leaching studies were employed in the study. Dissolution occurred in the following three ways: by the cyclic action of the Fe3+/Fe2+ redox couple, by galvanic interaction between Mn02 and the sulfide minerals, and because of chlorine evolution from the system. The later two routes were found more effective at higher HCI levels. PbS appeared to be oxidized easily, whereas CuFeS2 was the most difficult to dissolve. ZnS dissolution fell in between PbS and CuFeS2.

Jan 1, 2002

By B Davis, A H. Benzer, A N. Mainza, C M. Evertsson, L M. Tavares, M M. Hilden, M S. Powell, C Rule, G Asbj÷rnsson

The Mogalakwena North Concentrator of Anglo Platinum Operations was built with the capability to allow for future projected expansion. Several research groups, currently working with Anglo American on collaborative research over a range of projects, were brought in to review the existing operation, with a view to releasing some specific bottlenecks and providing specialist design input to the potential plant expansion.Based on a thorough review of the high pressure grinding rolls (HPGR) and crushing circuit, a wide range of de-bottlenecking opportunities were identified. This was followed by a series of surveys to provide performance measurements and to model the circuit in detail. From this effort a full simulation of the plant has been developed, including updated models of the HPGR, crusher, bins and screens. These models have been implemented in the researchersÆ Model Development Kit (MDK) version of JKSimMet, and in a prototype dynamic simulator based on the Matlab Simulink software.The observations, measurements and simulations have provided guidance and quantified the benefits of some proposed circuit modifications. Based on these findings a number of upgrades are being planned, with the aim of ensuring full utilisation of the installed equipment. The circuit demonstrates a potential expansion of over 30 per cent through minor improvements, and a 70 per cent increase in capacity with the addition of some strategic equipment.The HPGR-crushing upgrade project demonstrates the potential benefits of nurturing disparate Research groups into a strong inter-disciplinary technical team capable of supporting operational needs while developing future technology.CITATION:Powell, M S, Hilden, M M, Evertsson, C M, Asbj÷rnsson, G, Benzer, A H, Mainza, A N, Tavares, L M Davis, B, Plint, N and Rule, C, 2012. Optimisation opportunities for high pressure grinding rolls circuits, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 81-94 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By L. Garner McDonald

The U.S. Bureau of Mines tangentially impacted potential coal-cutter bit shank materials against sandstone to investigate the potential of the materials to ignite natural gas by a friction-generated hot streak. The shank material samples were mounted in a 24-in, 550-lb flywheel, which was rotated at surface speeds of 400 to 900 sfpm. The sandstone was advanced toward the rotating flywheel at feed rates of 1 mil per impact. The atmosphere mixture was 7 vol pct natural gas in air. Three grades of polycarbonate resin, an ultra-high-molecular weight polyethylene, and a zinc alloy (ZA27) were among the potential materials. None of these materials caused ignition of the methane at any of the three test speeds (400, 600, and 900 sfpm), but the above materials do not have sufficient strength to hold a carbide tip during coal cutting. Of the materials having sufficient strength to hold a carbide tip, three nickel-based alloys proved less likely to cause a natural gas ignition than did iron-based alloys such as 4340 (a commonly used shank material for coal cutters).

Jan 1, 2010

By Siwiec A

The laboratory investigations which are necessary to evaluate the mineral processing effectiveness usually include density separation of narrow size fraction of the feed and one of the products. In each size - density fractions the content of valuable mineral has to be determined. These data and yield in each size - density fraction can be specified by a matrix of partition coefficients. They are counterparts of recoveries. These coefficients can be compared with the mean recoveries at each density or size fraction or the total recovery, to determine which density - size fractions are processed in the best or worst way. The basic categories are: vector of metal content l _i 1711, 7t2, òòò, ltM I ò vector of particle size distribution x = I d1, d2, ..., dN I ò matrix of partition coefficients P11, P12, Pi N P _ P21, P22, ..., P2 N PM1 PM2..., PMN These three conceptions allow one to determine all the basic metallurgical parameters of a mineral processing unit. Losses of valuable mineral are connected with: ò mineralogical composition of the ore (types of minerals, their properties, dissemination, crystallochemical affinity, type and properties of gangue minerals), ò applied technology and technical equipment (beneficiation as a stochastic process, processing methods, process control, intergrowth liberation, water quality). Examples of application of the analytical method proposed are given for zinc - lead and coal processing plants.

Jan 1, 1993

By T. S. Lundy, J. Askill

J. Askill and T. S. Lundy (Oak Ridge National Laboratory)—Moore has proposed a simple correlation between the activation energy for solute diffusion in fee metals and the atomic volume of the diffusing species using both tracer and chemical-diffusion data. The first point we wish to make is that it is wrong to attempt such correlations without separating the two types of data. Activation energies obtained using tracer techniques cannot, in general, be directly compared with those obtained from chemical-diffusion experiments. A knowledge of the variations of chemical potentials with composition is necessary and chemical-diffusion data must be corrected for such variations, even for dilute alloys, before a comparison is possible. Secondly, for nickel, iron, aluminum, and lead, Moore neglected a number of recently published works, e.g., Al26 and Mn54 in aluminum,46 cr51 in nickel,47 and Fe55 in iron.48 These and others should have been used. If one considers only the tracer diffusion data, there is left no simple correlation of the type proposed by Moore. For example, in the case of solute diffusion in aluminum the only reliable tracer data listed by Moore are for zinc and aluminum. The nickel, cobalt, and iron data of Agarwala49 are representative of near-surface diffusion-not bulk diffusion. In conclusion we suggest that for tracer diffusion data in these fee metals there is no justification for proposing any simple correlation of activation energy with atomic volume using the limited data that are presently available. R. H. Moore (author's reply)—The writer has proposed a simple correlation which is useful in estimating the internal consistency of diffusion data. The accuracy of the correlation is, of course, a function of the number of data available. Lundy and Askill take issue with the writer's decision to include data for the systems: nickel, iron, aluminum, and lead, taking the view that the data are insufficient to establish the correlation. The writer agrees that the data are insufficient and has cau- tioned the reader that the correlation is tentative in these instances. Inclusion of these systems is justified by the interesting trends the correlation reveals. For example, the distinction between interstitial and substitutional diffusion may be clearly established, Figs. 4 and 6, and the behavior of transition elements and nontransition elements is indicated to parallel the behavior illustrated by the silver and copper systems. Lundy and Askill have singled out the aluminum system for special criticism. The writer chose to discuss the data for diffusion of iron, nickel, and cobalt in aluminum in the terms used by the original authors9 and has included the comments of Balluffi.l0 The writer did not intend the reader to conclude that data for these elements should correlate with data for the nontransition elements as Lundy and Askill have evidently assumed. Iron, nickel, and cobalt form intermetallic compounds with aluminum, so the activity coefficients of these elements may be expected to deviate markedly from unity. This may account for the low frequency factors observed by Hirano.9 The nontransition elements, on the other hand, yield relatively simple phase diagrams with no evidence for intermetallic compound formation as in the case of iron, nickel, and cobalt. In dilute solution, Henry's law should be closely obeyed, the activity coefficients should not deviate markedly from unity, and the effect on the activation energy should not be large. The accuracy of the correlation applied to these systems will improve as the data is extended. It does not seem unreasonable to conclude that its extension should be encouraged.

Jan 1, 1965

By J. R. Nettle

The purpose of these studies by the Federal Bureau of Mines was to determine the feasibility of refining low-grade hafnium by an inert-gas-shielded molten-salt electrorefining technique to produce a hafnium metal meeting reactor specifications. The techniques were adapted from those used success-fully for titanium electrorefining. Three electrolytes containing hafnium chlorides were developed from which deposits having a Brinell hardness of 170 or below were recovered. A KC1 + NaC1 + HfC14 electrolyte produced deposits in the hardness range of 140 to 165 Brinell. Deposits with a hardness range of from 132 to 152 Brinell were pro-duced from an electrolyte composed of KC1 + LiC1 + HfC14. A third electrolyte composed of NaC1 + K3HfC17 produced deposits with a hardness as low as 139 Brinell. In a fourth electrolyte, composed of NaC1 + K2HfF6, a measure of refining was accomplished, but under the test conditions no metal meeting specifications was recovered; none was softer than 174 Brinell. A number of metallic impurities were reduced in quantity by the electro-refining process, notably iron, which normally was reduced from 250 p.p.m. to less than 50 p.p.m. Magnesium generally was reduced from 680 p.p.m. to less than 80 p.p.m. Manganese content was also reduced by the electrorefining process. Sponge containing 90 p.p.m. Mn yielded deposits containing a maximum of 50 p.p.m.; some deposits contained only 10 p.p.m.

Jan 1, 1961

By J. E. Friant

The Mini-DiscTM cutter drill bit is a radical design departure from the traditional tri-cone rockdrill bit. Miniature disc type cutting tools as small as 3.25 inches (82.5 mm) diameter are fitted to a bit body to cut individual concentric kerfs. The action is the same as that commonly used on large tunnel boring machines but miniaturized. The high performance rate and efficiency of a disc cutter are the result of producing a large proportion rock chips rather than sand or powder. The Mini-DiscTM drill bit, referred to as the “Disc Bit” has other unique features as well. It can be re-greased between runs. It can be rebuilt in the field in about 15 minutes, cutters can be replaced and the Disc-Bit appears to require less down hole hydraulic power than conventional bits. Thoroughly tested in the laboratory, the bit has recently been undergoing field trials in well drilling, blast hole drilling and shaft drilling. As any engineer knows, the laboratory can not shake out all the problems but it eliminates the more glaring weaknesses. Performance results have been exhilarating, and a few mechanical problems were discovered and largely overcome. This paper is a progress report.

Jan 1, 1999

By C. J. Wilhelm

The Carthage field, in Pamela County, Tex., is one of the largest gas-condensate in respect to both areal extent and volume of recoverable gas in the United States. The field (shown in fig. 1) is approximately 25 miles long by 20 miles wide on a southwest to northeast axis and includes 306 producing wells as of July 1, 1948. 3 distinct reservoirs in the Rodessa and Sligo formations have been found in the Carthage area the two main producing zones being the Upper and Lower Pettit, less important production being found in the Hill zone. Although a small amount of commercial production has been obtained in the Travis Peak formation, it has not been included in this report. An engineering study has been made by Bureau of Mines engineers, with the ultimate objective of arriving at an estimate of the gas reserves, by application of the data made available by the operators in the Carthage field. During World War II the Bureau of Mines submitted a restricted petroleum-engineering report on the Carthage field to the Petroleum Administration for War, at which time (March 1944) the development consisted of only 19 producing wells, 7 of which were dual completions. Because of the restricted nature of the first report and the limited development at the time of writing, a more complete investigation and subsequent publication was considered advisable. Bureau of Mines engineers have made use of all available records such as electric logs, drilling-time logs, core descriptions and results of core analyses, well-completion records, and production data in developing this report.

Jan 1, 1950

By Barton G. Stone

"Sampling is the process of taking a small portion of an article such that the consistency of the portion shall be representative of the whole," (Baxter and Parks, 1939)."An orebody is a mixture of minerals in proportions that vary in different parts of the mass. As a consequence, the proportion of contained metals also varies from place to place. Therefore, a single sample taken in any particular place would not contain the same proportion of metals as does the orebody as a whole except by a highly improbable coincidence."The probable error, which would be very large if only one sample were taken, decreases with the number of samples, but it never disappears completely unless the samples are so numerous and so large that their aggregate is equal to the orebody itself, in which case the orebody would be completely used up in the process of sampling."Since carrying sampling to such an extreme would defeat its own purpose, some probable error is always present in actual cases and the practical objective is to reduce this probable error to allowable limits. This means balancing the number of samples against the desired accuracy; if there are not enough samples the result is unreliable; if there are too many, the time and expense of taking them is excessive." (McKinstry, et al., 1948).In an actual orebody, the accuracy of sampling depends not only on the number of samples but also on their proper distribution throughout the orebody, for it would obviously be incorrect to take all of the samples either in a rich part or a lean part. Therefore, it is important to select the places in such a way that all parts of the orebody will be represented."

Jan 1, 2014

By D. Harrington

The primary objective of this paper is to discuss the hazards and furnish a list of recommendations for the safe operation of quarries and related works. They have been compiled from Bureau of Mines publications covering the safety experience of engineers before and during the year in the mineral industry,5 from a publication of the National Safety Council, Inc.,6 from explosives recommendations made by various explosives manufacturers,7 and from suggestions obtained from quarries visited. The second objective is to describe and illustrate safety devices, practices, and quarrying methods. The quarrying and related industries of the United States had a lower accident-frequency rate than either the metal- or coal-mining industry as reported for 1942.8 However, the quarry industry ranked eleventh in 15 major industries during 1942 in lost-time accident fre¬quency; metal mining ranked fourteenth and coal mining fifteenth.

Jan 1, 1950

By David K. Ingram

Research performed by the U.S. insurance industry has determined that mine subsidence is uninsurable. Consequently, the insurance industry has decided not to voluntarily offer mine subsidence insurance. The U.S. Department of the Interior has long been investigating the effects of mine subsidence. These investigations have resulted in Federal regulations and controls of mine subsidence. This U.S. Bureau of Mines report generally describes mine subsidence, the development of mine subsidence insurance programs, and the eight current mine subsidence insurance programs in the United States. The States that have these subsidence programs include Colorado, Illinois, Indiana, Kentucky, Ohio, Pennsylvania, West Virginia, and Wyoming. Major aspects of the programs include history, administrative and operational procedures, insurable structures, recognition of mine subsidence, major exclusions, claims, insurance premiums, and the economic health of each program. Addresses of agencies involved with mine subsidence insurance are also given. Information within this report can be useful for residential and commercial property owners and mine operators. States that are considering starting or have an existing mine subsidence insurance program can also use this report as a model for initiating or modifying their programs.

Jan 1, 1993

By S. H. Lorain

This paper is one of a series being published by the Bureau of Mines describing the mines and mills and subjects related to mining in western mineral areas. Although mining districts in the Tobacco Root Mountains are numerous there is a strong similarity in the character of the ore deposits and in the climatic and economic conditions affecting mining throughout the region. Individual mines are small, but the production of lode mines

Jan 1, 1937

By K Ionkov

The oolitic iron ore reserves in Lisakovsky, North Kazakhstan represent quite a challenging deposit both from a technological and from a resource point of view. The difficulties in processing such types of ore are connected with the extremely fine dissemination of phosphorus and gangue minerals inside the oolitic formations. The goethite crystals are cemented in their structure by aluminosilicates with quartz and other gangue minerals and dissemination is so fine that they are not separable by physical methods. The laboratory tests performed for dephosphorisation show that the combination of alkaline roasting followed by low intensity magnetic separation and acid leaching enables the obtaining of high grade iron concentrate. The magnetic separation performed ahead of leaching is effi cient as a means of buffering the high pH by washing out the soluble salts and the excess of base and after leaching facilitates the removal of secondary liberated gangue minerals in the non-magnetic fraction. As a consequence, phosphorous content is dropped to a more acceptable level for the ferrous metallurgy and iron grade and recovery reach 61.6 and 80.8 per cent respectively.

Jul 11, 2011

By L. D. Tracy

This is the third of the series of reports on coal-mine royalties and leasing conditions in Illinois. The results of the study of District VI were published as Serial No. 2726, January, 1926, and those of District VIII as Serial No. 2745, April, 1926, of the Bureau of mines. The counties of Macoupin, Sangamon, and Montgomery, which are three of the principal coal-producing areas in the northern part of District VII, have been chosen for this report because these counties cover an entirely different part of the State than do the two districts already covered. Some leases in, Randolph and Washington counties are included as they are in the southern part of the district, and the data happened to be readily available.

Jan 1, 1926

By Hossein Ghaedi, Hadi Fattahi

Despite the significant role of coal in the economic progress of nations, the occupational and health risks associated with its mining pose a major concern for industry stakeholders. The occurrence of roof collapses in coal mines remains a critical factor leading to substantial loss of life and financial damages for miners. Therefore, accurately predicting the roof fall rate (RFR) holds paramount importance. However, the uncertainty surrounding rock parameters in mines hinders the application of conventional methods to assess roof collapse rates in coal mines. To tackle the challenges associated with predicting roof fall rates in underground coal mines, this study proposes a novel solution by leveraging the Rock Engineering System (RES) method. The investigation is grounded in a dataset comprising 109 data points, encompassing crucial input parameters like depth of cover (DOF), primary roof support (PRSUP), intersection diagonal span (IS), mining height (MH), and coal mine roof rating (CMRR). In the model construction phase, 80% of the data (87 points) were utilized to build the RES model. A critical aspect of this study involves the evaluation of the RES model’s performance against alternative regression techniques, namely linear, power, exponential, polynomial, and logarithmic regression. This comparison was executed using the remaining 24 data points (20% of the dataset) for rigorous evaluation. Employing key statistical metrics such as mean square error (MSE), root mean square error (RMSE), and squared correlation coefficient (R2), the study systematically demonstrated the superior accuracy of the RES-based method compared to other approaches. In conclusion, the outcomes strongly support the efficacy of the RES method in predicting roof fall rates, not only in the specific case studied but also indicating promise for its application in other underground coal projects. This underscores the potential of the RES method as a reliable and versatile tool for forecasting roof fall rates in the complex and critical context of underground coal mining.

Mar 19, 2024