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By Jianbo Lan, Desheng Huang, Xiaoying Qiu, Zhaohua Ke, Liusheng Ge, Xinjin Xiao, An Guo, Qiaofa Lan

Magnesium salt rare earth enrichment (MREE) is a crucial intermediate raw material in the deep processing of rare earth elements and material preparation, serving as a front-end raw material for the synthesis of rare earth oxides. With the current disposal process for MREE, neutralization slag with high rare earth residue is generated during further extraction of rare earth from the MREE and accumulates in huge piles. Therefore, the combined disposal process of MREE and neutralization slag was put forward. MREE was solubilized using 4 mol/L sulfuric acid to achieve an endpoint pH of 0.75, dissolving the rare earth and obtaining an acid solution. The MREE and neutralization slag were added in a mass ratio of 1:2 to the acid solution sequentially. The pH of the endpoint was controlled to 4.8~5.0 for neutralization and decontamination. This resulted in the production of rare earth sulfate liquid of similar quality to the original MREE disposal process, meeting subsequent extraction requirements. The neutralization slag underwent a water washing process, with two washes (first with 0.2 mol/L acidity water at a solid-liquid ratio of 1:2 and second with deionized water at a ratio of 1:4), resulting in water-washing slag with a rare earth content of 0.24% and a rare earth yield of 97.08%. Notably, zero wastewater discharge was realized. This innovative process effectively addressed the challenges of high rare earth residue in neutralization slag and stockpile accumulation, offering valuable theoretical and practical insights for MREE disposal.

May 31, 2024

By Binbin He, Baiwei Lei, Rehamutula·Rouzi, Zheng Wang, Chao Li

Methane explosions are highly destructive and constitute a primary hazard affecting mine safety. Seals are commonly employed to obstruct the propagation of methane explosions within tunnels, with the aim of reducing the damage caused by methane explosions. In order to study the influence of the seals’ position on the parameters of methane explosion damage, this study takes the Lake Lynn Experimental Mine No. 501 in the United States as a background case. It investigates the methane/air explosion damage parameters at different positions of seals in a fully sized roadway using the GASFLOWMPI code. The coupling mechanism between methane explosion gas expansion and reflected waves is analyzed. Finally, the variation patterns of explosion damage parameters are analyzed based on explosion damage criteria. The results show that as the distance increases between the seal and the explosion source, the maximum overpressure and impulse at the seal decrease exponentially, and the decrease is more significant when the seal is closer to the explosion source. The maximum velocity and maximum dynamic pressure increase first and then decrease, reaching their maximum values at approximately 115 m. They are approximately 163.355 m/s and 30.485 kPa, respectively. According to the analysis of explosion damage criteria, it is found that overpressure damage is the main form of methane explosion damage. But the damage of impulse and dynamic pressure is not be ignored. The relative position between the seal and the gas expansion area significantly impacts the parameters of methane explosion damage due to the coupling effect of gas expansion and the overpressure reflected wave from the seal. When the seal is set in the gas expansion zone, the further the seal is from the explosion source, the greater the dynamic pressure damage and the more minor the overpressure and impulse damage. The closer to the explosion source, the more significant overpressure and impulse damage changes. When the seal is set outside the gas expansion zone, the further the seal is from the explosion source, the more minor the overpressure and impulse damage to the seal, and the dynamic pressure damage increases first and then decreases.

Apr 24, 2024

By Eileen Ashworth

Introduction A study was completed that investigated the enrollment in mining engineering programs in 24 universities and colleges. All programs considered in the study award four-year bachelor of science degrees in mining engineering. They also provide all the engineers for the mining industry and a large portion of the geotechnical engineers working on environmental problems, storage of hazardous waste, civic, and Federal government underground projects. The numbers used as the base for the study are those reported by each program to SME-AIME and published yearly (SME, 1986). Data for the study came from the period 1975-1985. Also, since some programs include students in related disciplines and special categories, such as cooperative students, a few inaccuracies were unavoidable. A 23-page document has been prepared that reports on the overall picture of current enrollment, the trends, and discusses the results, perceived effects, and what can, or should, be done. There has been an obvious, and dramatic decrease in total undergraduate enrollment since the late 1970s. In 1978, 3117 students were enrolled. In the 1985 fall semester, enrollment was 1022, less than one-third. There were 485 seniors, 265 juniors, 147 sophomores, and 125 freshmen. The downward trend in total enrollment is likely to continue for at least another two years. Class size The catastrophic drop in enrollment is shared by all programs across the country. It does not discriminate between types of programs, coal or hard rock mining, or location. In general, 1985's enrollment is about 30% of whatever the maximum enrollment was in any program, though this varies from the teens to 50%. The latter percentage occurs only for some programs with special circumstances, particularly new programs not well established in the late 1970s. The beginning of the decline in enrollment has occurred at slightly different times as affected by the demise of each program's local industry. The numbers in each class produced from a specific freshmen year (Fig. 1) are worthy of comment. The dramatic drop in enrollment for all classes after 1982 is clearly demonstrated. The timing coincides with the general downturn in the mining industry, when many employed engineers were laid off and new graduates could not find jobs. Also, significantly fewer students are being attracted to mining programs as freshmen. The number of seniors shown seems inappropriate. Where did so many seniors come from and why are so few graduates produced? There is an increasing trend for students to take four-and-a-half or five years to graduate. Therefore, they are counted twice, once when they are first classed as seniors and again the following year. Some students purposely delay graduation to obtain more summer work experience and take additional courses. They believe that this gives them a better

Jan 8, 1986

By Sejong Kim, Younghoon Moon, Youngseon Lee, Eunyoo Yoon, Yonghyun Song

"Mg alloy has a high specific strength, however, their thickness reduction was limited on most parts because of their poor stiffness. Since the modulus of rigidity is an intrinsic property, improvement of modulus of rigidity to the enhancement of stiffness is impossible. Therefore, the modification of shape and structure is available method to enhance the stiffness of real part fabricated by Mg alloy sheet. There are many thin walled parts which are located in outer section of electromagnetic system.Poor stiffness is often shown on wide surface area part with steel sheet, which has also high modulus of rigidity. In these cases, various groove patterns are used to increase the stiffness of part. However, some different methods have to be used when general groove pattern can’t be used. So, we would like to propose some new method to high stiffness on thin walled precision forging of Al or Mg alloys.An effect of proposed method on stiffness enhancement can be confirmed by fabrication of prototypes as well as structure and forming analysis based on FEM."

Jan 1, 2015

By Tiago de Souza, Caroline Gonçalves, Carlos Eduardo de Castro, Everton Dias

The Miraí plant from Votorantim Metais, has two screening stages to the bauxite classification after scrubbagem. The final product has hold the larger size of 0,84 millimeters (20 mesh). There are two sieves Haver & Boecker (model R-TE 3658 x 10972), which have four modules with cut size sieves of 10 mesh (1.70 millimeters) and ¼ inch (6.35 millimeters) on the primary screen, and 20 mesh (0.84 mm) on the secondary screen, all made of polyurethane. The actual configuration was established according to the empirical tests realized that aimed the increase material load on the secondary screening. However, having in mind the screening process improvement and use the fractions smaller than 0,84 mm, which have significant levels of Alumina and low reactive silica, was proposed a new test of change the sieves opening for 6 mesh in the primary screen and 28 mesh for the secondary sieve. The objective of this work was measure the ore alterations on the particle size distribution on the screening steps, increasing the plant weight and ratio recovery before and after the test.

Jan 1, 2014

By Woo, Hur, Kim, Ki Nam, Seung Min, Kyoung Sik

Tandem cold mill (TCM) is a process to obtain flatness as well as thickness desired by the customer by rolling hot-rolled coils continuously. The final stand of the TCM plays the most important role of flatness control, which usually uses the real-time measurement at the exit. However, as the material property increases, it is not easy to handle flatness with only the final stand. In order to overcome such a limitation, we propose a feedback control method to strengthen flatness control for non-final stands. The proposed method was tested in an actual production line, and the effect is proved for 45K or less steel grade.

Oct 1, 2019

By R. H. Grau, C. D. Taylor, A. L. Martikainen

Utilization of belt air in underground coal mines has been discussed extensively during the last decade. The Final Report of the Technical Study Panel on the Utilization of Belt Air and the Composition and Fire Retardant Properties of Belt Materials in Underground Coal Mining formed by the Mine Improvement and New Emergency Response (MINER) Act of 2006 recommends research on leakage, use of booster fans, and escapeway safety. This paper discusses the role of ventilation modeling in evaluating primary escapeway pressurization in a three-entry development system to improve emergency escape in a coal mine using belt air. The intake entry of the National Institute for Occupational Safety and Health (NIOSH) Bruceton Experimental Mine was pressurized using a 1.1-m (42-in.) diameter, 37 kW (50 hp) fan. The work details air movement in the simulated three-entry system and the resulting leakage patterns. Three mine ventilation software packages were compared to analyze their performance in predicting the airflows and leakage conditions with different fan settings. NIOSH researchers found that the measurement results correlated well with the results of modeling.

Jan 1, 2010

By J Safarian, D Hariswijaya

Treating bauxite residue as an alternative source of metals for iron and aluminium industry is an approach to promote circular economy in metal industries. Reduction of metal oxides with H2-based process is an important step on decarbonisation of metal industry. In this study bauxite residue pellets were prepared and were reduced with different H2-H2O gas compositions at different temperatures which yielded with various degrees of reduction. The bauxite residue pellets were made from a mixture of bauxite residue and Ca(OH)2 powders and sintered at 1150°C. Hydrogen reduction was carried out on the oxide pellets using a resistance furnace at elevated temperatures in controlled reduction atmosphere of H2-H2O gas mixtures which resulted in reduction of iron oxides in the pellets. Unreduced and reduced pellets were subsequently heated to 1400°C to study their smelting behaviour using differential thermal analysis (DTA) and thermogravimetric analysis (TGA) technique to investigate the evolution of phases related to slag formation via smelting. Equilibrium module of Factsage™ ver 8.1 was utilised to analyse results of thermal analysis. It was observed that Tricalcium phosphate-β (CaP2O8), Bredigite (Ca7Si4MgO16), Rankinite (Ca3Si2O7), and calcium alumino ferrite (Ca[Al,Fe]6O10) were formed during thermal analysis as intermediate phases. The initial slag formation for sintered and reduced pellets occurred at 900°C which mainly contains calcium and small amount of strontium component. The slag formation rate increases significantly starting from 1100°C when iron oxides started to form initial molten slag phase which then followed by other oxides dissolution in the system. Gas formation was observed at 1180°C and it was found that the gas to be released from unreduced pellets is O2 meanwhile the gas to be released from reduced pellets is SO2 gas. Gas formation rate for both pellets start to increase at 1280°C when the remaining chemically bonded gas start to be released from the system.

Jun 19, 2024

By T. A. Rickard

Technology has no recognized rank in what is called polite literature; the subject-matter of engineering is not supposed to lend itself to artistic treatment; we are the hewers of wood and drawers of water to the high-priests of learning that live on the cold summit above our humbler dwellings. Therefore the hierophants smile at the notion of 'style1-" that curiously personal thingy-in technical writing. The "great art" of Pater, the "inevitable phrase" of Raleigh, the "note of distinction" that Arnold demanded are said to be beyond the scope, as they are supposed to be beside the need, of a writer on geology or engineering. This is a narrow view. Science, no less than belles lettres, calls for the best exercise of the human intelligence; the art of writing should be employed as skilfully and as earnestly in a description of the structure of the Sierra Nevada, or of the construction of a tunnel through the range, as in a rhapsody welcoming the rosy fingers of the dawn. The idea still lingers that fine writing does not befit technology, even though the masters of the Victorian period-Huxley, Tyndall, Ruskin-proved that science is worthy to be arrayed in the best robes that the looms of thought can weave. At the beginning of these lectures I quoted Barrie's remark touching the inability of the scientific man to express himself. That imputation has been passed to the technologist, whose utilitarian pursuits are supposed to make him too clumsy for the refinements of human speech. We may not have acquired the self-consciousness of those writers on Art whose "power of expression is so cultivated that their sensual caterwauling may be almost mistaken for the music of the spheres"; nor can we imitate the politicians, who have the ability to speak far beyond anything that they may have to say; but we too have a litera-

Jan 1, 1931

By T. J. Lien

AMAX Coal Company's Belle Ayr coal dryer is the first industry attempt to commercialize sub-bituminous coal drying which has been the subject of laboratory and pilot plant tests for almost two decades. This paper presents the historical background, construction, start-up and operation of this adaption of fluidized bed coal drying technology to Powder River Basin coal. The flowsheet and operational problems encountered during plant start-up are discussed together with general material balance and product quality.

Jan 1, 1990

By A. Hasselbring

Sub-Level stoping was used in this country at least as early as 1912, at the Magpie mine in Michipicoten. The fundamental principles of the system are the same wherever it is used, but modifications have been adopted in the Michigan iron mines and in several Canadian mines. It is a system whereby a suitable body of ore may be developed quickly and worked cheaply, with a low initial expense, and by miners of quite ordinary ability. The basic method, described in the following pages, may be modified to meet conditions where one or more factors are not in accord with normal sub-level stoping requirements. In suitable ground, sub-level stoping is probably the most satisfactory method yet devised for underground hard-rock mining. It is so simple, straightforward, and safe that no special training of a crew is necessary. Any miner capable of drifting and raising can carry on the work necessary for sub-level stoping after the shaft has been sunk. The method is suitable, however, only for reasonably wide ore-bodies, the minimum width of ore to which it can be economically applied being somewhere in the neighbour-hood of thirty feet. The development programme is simple. Assuming, for purposes of illuslustration, an ideal ore-body, two thousand feet long, dipping nearly vertical, and varying in width from forty to a hundred feet, this programme would be as follows. The shaft should be sunk on the footwall side about sixty feet outside of the ore-body and near its centre. Levels are then established at suitable intervals, usually 125 feet. On each level, a cross-cut is run to the ore-body, and there a main-haulage drift is driven in either direction to the end of the ore. Cross-cuts are then run at 25-foot intervals, so that ore-chutes can be spaced about 25 feet centre to centre each way. It is not necessary that these cross-cuts be extended to the walls of the ore-body, if the position of the walls is known; they are extended just far enough to make room for the correct location of the chutes.

Jan 1, 1934

By Jorge MRS Relvas

Recent research both on active and fossil systems has demonstrated that shallow subseafloor replacement processes are not only viable depositional mechanisms for massive sulfide mineralization, but likely contributed as a major component of the mineralization occurring in large VHMS deposits and in many present-day seafloor hydrothermal systems. In the giant Neves Corvo deposit, as in many others VHMS deposits of the Iberian Pyrite Belt, there is overwhelming evidence for silicate-sulfide replacement processes being largely responsible for the efficiency of the ore-forming systems and huge size of the deposits. Textural evidences at all scales, coupled with a well-constrained mass-balance geochemical analysis, indicate that extensive replacement in the lavadominated volcanic rocks of the footwall sequence, and disseminated replacement mineralization in the volcaniclastic and/or sedimentary units were major mechanisms of ore formation in the Neves Corvo deposit. Shallow metal deposition prior to fluid discharge on the seafloor is likely to play a major role in seafloor massive sulfide mineralization. This premise should be envisaged as critical in evaluating the economic potential of seafloor resources, and should certainly be part of the equation when plans for seafloor mineral exploration missions are drawn.

Sep 14, 2011

By G. Kleyn

"Sub-standard practices and their adverse impact on safety performance remain a challenge in the South African gold mining industry. The purpose of this study was to investigate the root causes of sub-standard practices and the effect on safety performance in South African gold mines. The focus of the study was on the underground production operations at a gold mine in the Free State. The study consisted of three parts: a personal investigation into the causes of sub-standard practices at the mine, a comparison with the results of a cultural study performed at the West Wits mines, and a behavioural survey.The studies described in this article yielded similar results in terms of the key drivers behind sub-standard practices. It was found that substandard practices had a number of causes, and the origin lies within the habits, attitude, and behaviour of employees. Current methods of addressing sub-standard practices and improving safety performance were found to discourage employees from performing work safely and according to procedure. It was concluded that the lack of critical behavioural habits for the given work environment and job title could possibly be the primary reason for the occurrence of sub-standard practices. IntroductionSince the implementation of the Mine Health and Safety Act, 1996 (Act 29 of 1996) and the Mine Health and Safety Regulations, the South African mining industry has been striving to improve health and safety performance and has placed great emphasis on adherence to mine standards.The Act requires employers in the mining industry to report accidents, incidents, and dangerous situations to the Regional Principal Inspector of Mines in their area. The data provided by employers is captured and analysed by the South African Mines Reportable Accident Statistical System (SAMRASS) and made available for public viewing (Department of Mineral Resources, 2011).A review of the national mine-related accident statistics shows clearly that the South African gold mining industry has improved its safety performance markedly over the past decade, but is still facing major challenges (Figure 1). These include meeting the Mine Health and Safety Milestones (Department of Mineral Resources, 2011)."

Jan 1, 2016

By Linda C. M. Elliot, Liangxue Liu

"The deposition of tailings under water is considered to be one of the most environmentally promising and potentially cost effective methods to reduce or eliminate acid mine drainage from tailings. One of the concerns of subaqueous deposition has been that metals may leach into the cover waters, thereby increasing aqueous metal concentrations to higher than acceptable limits. This potential was seen to have an even greater possibility for impact when the tailings are deposited under acidic lake water.The following paper summarizes the results of subaqueous tailings pilot column test work conducted to determine the effects of subaqueously deposited tailings on lake water and tailings pore water. Two types of tailings were tested: high sulphide tailings (pyrrhotite concentrate), and low sulphide tailings (end of pipe slime tailings).Data was collected from five columns over a 13 month test period. The results indicated that a stagnant I 000 mm water cover was capable of maintaining the underlying tailings in a reducing condition. The upwards diffusion of pore water resulted in a pH increase in the waters overlying the thickened pyrrhotite tailings and the pyrrhotite tailings with a shallow cover of substrate. A conductivity gradient between the tailings and the water cover caused a diffusion of salts upwards into the overlying water column. Precipitation noted at the tailings water interface may be related to the precipitation of ferric oxyhydroxides, which resulted in a decrease in Fe concentrations noted in the water cover. Other metal concentrations did not exhibit significant increases in the water cover. A sulphate concentration gradient between the tailings and the water cover may have caused the diffusion of SQ4 from the tailings into the water cover."

Jan 1, 1997

By N. P. Goss

ASTERISM appearing in X-ray Laue dia-grams is an extremely sensitive index of changes in the internal structures of indi-vidual grains of polycrystalline metals. It indicates the existence of various forms of subboundary structure or subdivision within the grain. The present viewpoint is that the grain is made up of lattice blocks having substantially the same size and shape.1-4 When these blocks all assume exactly the same orientation, the crystal is perfect and asterism is absent. Cleaves and Thompson5 observed that the hardness of iron is virtually constant over a range of grain sizes. It is quite possible that the subboundary structure caused this, and that the latter is just as important as grain size itself. While the experiments reported here are not con-clusive, they do support this viewpoint. Metals can, under certain conditions, be prepared entirely free from asterism, but this preparation does not necessarily require long heating or slow cooling, as will be shown here. In this paper a distinction is made be-tween mosaic and distorted grain struc-tures but the difference is only a matter of degree. In a previous paper9 it was shown that the grains can become distorted even during heat-treatment. The block structure exists inherently, even in a perfect crystal; the size and shape of these crystallites, or lattice blocks, varies, depending upon a number of factors. Goetz, for example,7 has shown that a metal before crystallizing from the molten state must go through a paracrystalline phase with oriented groups of atoms about 10-14 to 10-15 c.c., or 10 5 cm. in size.

Jan 1, 1940

By N. P. Goss

ASTERISM appearing in X-ray Laue dia-grams is an extremely sensitive index of changes in the internal structures of indi-vidual grains of polycrystalline metals. It indicates the existence of various forms of subboundary structure or subdivision within the grain. The present viewpoint is that the grain is made up of lattice blocks having substantially the same size and shape.1-4 When these blocks all assume exactly the same orientation, the crystal is perfect and asterism is absent. Cleaves and Thompson5 observed that the hardness of iron is virtually constant over a range of grain sizes. It is quite possible that the subboundary structure caused this, and that the latter is just as important as grain size itself. While the experiments reported here are not con-clusive, they do support this viewpoint. Metals can, under certain conditions, be prepared entirely free from asterism, but this preparation does not necessarily require long heating or slow cooling, as will be shown here. In this paper a distinction is made be-tween mosaic and distorted grain struc-tures but the difference is only a matter of degree. In a previous paper9 it was shown that the grains can become distorted even during heat-treatment. The block structure exists inherently, even in a perfect crystal; the size and shape of these crystallites, or lattice blocks, varies, depending upon a number of factors. Goetz, for example,7 has shown that a metal before crystallizing from the molten state must go through a paracrystalline phase with oriented groups of atoms about 10-14 to 10-15 c.c., or 10-5 cm. in size.

Jan 1, 1940

IT will be recalled that when educational instruction for the mineral industry began at Freiberg, at the beginning of the eighteenth century, the original aim was to organize and systematize the procedures previously followed by young men in gaining familiarity with the technology then in use. There must have been many other ideas current, even then, as to just what a young man needed to learn in order to become capable of assuming responsibility for the supervision and direction of such technical work. The problem in Europe was decidedly different from that in nineteenth-century America, because some of the European mines were actually owned and operated by the governing authority and the others were supervised, regulated, and taxed by it. The American problem was the efficient performance of technical operations; the European one was regulatory supervision. It was natural, therefore, that in the development of educational processes in Europe stress was laid on those factors which conserved and protected the interests of the state. The study of mineralogy and geology, leading to correct judgments as to the workability and value of mineral deposits; assaying, which gave the means of quantitative measurements, as did surveying; chemistry, which furnished a better basis of understanding for assaying, mineralogy, and geology; and physics and mathematics, which are the bases for the understanding and efficient use of mechanical appliances, became the core of systematic instruction for the mineral industry. It was early recognized that men could learn more than was already known about all of these subjects and education took on that dichotomy which still characterizes it; the teaching of established knowledge to the unlearned, and that of extending of the bounds of knowledge, now loosely termed research, which after two and a half centuries of work still shows

Jan 1, 1941

By Thomas T., Read

IT will be recalled that when educational instruction for the mineral industry began at Freiberg, at the beginning of the eighteenth century, the original aim was to organize and systematize the procedures previously followed by young men in gaining -familiarity with the technology then in use. There must have been many other ideas current, even then, as to just what a young man needed to learn in order to become capable of assuming 'responsibility for the supervision and direction of such technical work. The problem in Europe was decidedly different .from that in nineteenth-century America, because some of the European mines were actually owned and operated by the governing authority and the others were supervised, regulated, and taxed by it. The American problem was the e5cient performance of technical operations; the European one was regulatory supervision. It was natural, therefore, that in the development of educational processes in Europe stress was laid on those factors which conserved and protected the interests of the state. The study of mineralogy and geology, leading to correct judgments as to the workability and value of mineral deposits; assaying, which gave the means of quantitative measurements, as did surveying; chemistry, which furnished a better basis of understanding for assaying, mineralogy, and geology; and physics and mathematics, which are the bases for the understanding and efficient use of mechanical appliances, became the core of systematic instruction, for the mineral industry. It was early recognized that men could learn more than was already known about all of these subjects and education took on that dichotomy which still characterizes it; the teaching of established knowledge to the unlearned, and that of extending of the bounds of knowledge, now loosely termed research, which after two and a half centuries of work still shows

Jan 1, 1941

By Stephen Mansfield

In metalliferous mining operations, subdrill is that portion of the blast hole that is drilled below the target grade elevation, and in most cases loaded with explosives. Its primary aim is to enable efficient excavation down to the target floor level. Subdrill is often described as being expensive and that excessive subdrill should be avoided, as it can result in damage to the subsequent floor, lead to difficult drilling conditions and higher vibration levels. As a result, many operations aim to apply the bare minimum amount of subdrill in order to excavate to the target floor

Feb 1, 2020

By G. Avramovic-Cingara

Grain boundary characteristics and microstructural evolution are analyzed in a comparative study using orientation imaging microscopy (OIM/SEM) and transmission electron microscopy (TEM/SAD). The subgrain sizes and misorientations were determined by the OIM for aluminum deformed in torsion to equivalent strains between 0.2 and 4 over the temperature ranges of300-600°C and strain rates 0.01-1 s". The OIM gives clearer evidence of boundaries with high misorientation than does TEM, but it overestimates their frequency b y missing boundaries less than 1 0. T EM more clearly reveals low-angle arrays of widely spaced dislocations resulting in finer subgrain sizes than those indicated by OIM. The evidence supports a mechanism combining dynamic recovery (DRY), deformation band formation with permanent boundaries and geometric dynamic recrystallization (gDRX) in contrast to the hypothesis known as continuous dynamic recrystallization (cDRX).

Jan 1, 2004