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By P. Zhang, S. Al-Thyabat

"Phosphate rock contains traces of rare earth elements (REEs) and can be a secondary source of these critical materials as large tonnages of phosphate rock are mined annually. Attention has mostly focused on the extraction of REEs from phosphogypsum, which contains more than 70 percent of the REEs reporting to phosphate concentrate, with only limited work conducted on REE extraction from sand tailings and slime even though they account for 16 percent and 15 percent, respectively, of REEs mined with phosphate matrix.In this work, phosphate flotation tailings were upgraded by gravity separation and froth flotation. Gravity separation was conducted using a laboratory shaking table, while flotation was conducted in a Denver D-12 flotation cell. The concentrated tailings were then leached by nitric acid followed by REE extraction with solvent and ion-exchange resin.The sand tailings were assayed as having 2.6 percent phosphate (P2O5 ) and 198.1 µg/g REEs. It was found that the shaking table could produce tailing concentrate assayed as having 8.6 percent P2O5 and 616 µg/g REEs but with only 20 percent REE recovery, while the froth flotation produced froth concentrate assayed as having 8.1 percent P2O5 and 368.2 µg/g REEs with 63.5 percent REE recovery. Leaching the flotation concentrate with 5.2 M (25 percent) nitric acid followed by extraction with solvent and ion-exchange resin yielded precipitates with REE contents of 0.926 and 0.314 percent, respectively, compared with 0.716 and 0.213 percent when table concentrate was used.IntroductionRare earth elements (REEs) consist of a group of 17 elements: the 15 lanthanides along with yttrium (Y) and scandium (Sc). They are rare not because of their scarcity in the Earth’s crust but because they are rarely found in economic and mineable deposits. REEs are called “seeds of technology” because of their importance to some critical technological industries such as renewable energy, hybrid cars, electronics and batteries. On average, an electric car or a hybrid car contains about 10 kg of REEs (Grasso, 2012; Radhika et al., 2011).REEs are usually categorized into light (LREE) and heavy (HREE). LREEs consist of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pr), samarium (Sm), europium (Eu), gadolinium (Gd) and scandium (Sc), while HREEs consist of terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu) and yttrium (Y). About 200 minerals contain traces of REEs, but only three are considered economically significant: bastnasite, with the formula La,Ce(CO3)F; monazite, with the formula(Ce,La,Nd,Th)PO4; and xenotime, with the formulaYPO4 (Jordens, Cheng and Waters, 2013)."

Jan 1, 2016

By Gift Makusha, Dave Minney

Anglo Coal South Africa mines coal for both the domestic and export market using open cast and strip mining methods. To establish a mine, a process is set in place to gather ever increasing amounts of geological and metallurgical data to confirm a proven reserve. Increasingly, geotechnical data are also included in this process to confirm that reserve is easily and safely mineable. The mine design process is an iterative one using a combination of numerical modelling and empirical data to arrive at a mining layout that is both, practical, productive and safe. In South Africa it is a legal requirement to compile a code of practice to combat rock fall and slope instability accidents and these have to be revised annually, reinforcing the iterative process of continual improvement. To ensure best practise occurs, all Anglo Coal operations are subjected to annual 2nd party audits and ad hoc 3rd party audit by independent consultants. This paper attempts to explain the process described above in a concise, but understandable manner. 1.0 GEOLOGICAL SETTING The Ecca sediments date from the Permian period and the coal deposits were formed in glaciated valleys on a basement of Dolomite, Ryolite or Granophyre rock types. The sediments overlying the coal deposits are typically flat lying and multiple bedded. The sediments consist of mudstones, shales and sandstones and are generally capable of forming stable highwalls given the time that they must stand up for. Anglo Coal extracts coal from the Witbank, Highveld and Vereeniging coalfields. The Witbank coalfields contain five seams numbered from the base upwards, 1 to 5 Seam; Highveld coalfield the 2 and 4 Seam and the Vereening area the seams are described as Top, Middle and Bottom seams. Coal deposited over the basement Dolomite formation display very erratic dips, as contemporaneous subsidence occurred in some instances over sinkholes that were forming, resulting in local thickening of the coal deposit and resulting in strata that dips toward the centre of the sinkhole.

Jan 1, 2006

By Gregory M. Molinda

Coalbed discontinuities historically have been hazardous to mining as well as obstructions to efficient production. An effective means of mapping these features is needed in order to plan safe and efficient mine development. This Bureau of Mines report discusses the use of surface seismic techniques for this purpose. At a southwestern Pennsylvania mine, a system of coalbed discontinu-ities (paleochannels) was accurately mapped by the Bureau of Mines using borehole log methods and underground observation. This site was chosen to test the value of a high-resolution surface seismic reflection on technique for coalbed mapping. A statistical study performed at this mine indicated that the probability of accurately delineating this paleochannel system with conventional borehole methods was remote. A total of 1.47 miles of high-resolution seismic survey, comprised of four seismic profiles, was conducted in known and suspected coalbed discontinuity areas. Several test holes were drilled on the seismic lines in order to evaluate the interpretations. It was found, based on these and other existing boreholes, that it is possible to predict these dis-continuities. Paleochannel washouts were correctly predicted in several instances but in other instances were either incorrectly predicted or not predicted in areas of known discontinuities.

Jan 1, 1988

By Tom Pfitzer, Alice Correa, Meredith Hardwick

The past decade has brought significant changes in the use of risk-based criteria for safety within the U.S. Department of Defense. The Range Commanders Council (RCC) chartered a working group to develop and define risk acceptance criteria for protecting the general public and mission essential personnel from debris from launch ranges. This working group has continued to develop and update RCC Standard 321 as the needs of the ranges and range users have evolved. A revision to RCC Standard 321 is near finalization and will include casualty criteria, guidelines for assessing risks due to other flight hazards in addition to inert debris, and an overall risk management process for range safety. This paper reports on work in progress and includes several precedents which may prove important to the explosives safety community.

Jan 1, 2007

By Wern-ping (Nick) Chen

In concrete lined tunnels, formwork removal timing may be controversial. Contractors seek to strip the form as soon as possible, and designers seek to keep the formwork in place as long as practical to protect the fresh concrete. Formwork removal timing is normally specified as a function to its insitu concrete strength. This approach may work for smaller diameter tunnels, but fallacy occurs when applying this approach to larger diameter tunnels, since a larger diameter would experience more displacement than a smaller diameter tunnel from its own weight. Excessive deformation may fail a tunnel to meet its roundness criterion and overstress the lining causing cracking or falling from the crown. This paper presents a contractual mechanism to mitigate this issue.

Jan 1, 2008

By V. Labiouse, R. Gärber

The paper aims at clarifying the up-to-now misappreciated role taken by pore water on the design of deep tunnels in saturated porous media. Numerical simulations with a non-dimensional FEM-model emphasise the influence of pore water characteristics (in situ pressure and compressibility) and boundary conditions (lining permeability) on the short and long term underground-structure equilibrium states. These results cannot be achieved by means of monophasic total stress analyses. Dieser Beitrag untersucht den Einfluss des Porenwassers auf die Dimensionierung von tiefen Tunnelbauwerken in wassergesättigtem Untergrund. Numerische Simulationen mittels eines dimensionslosen FEM-Modells betonen den Einfluss der Porenwassereigenschaften (in-situ Druck und Kompressibilität) und der hydraulischen Randbedingungen (Tunnelausbaudurchlässigkeit) auf Kurz- und Langzeitverhalten des Untergrund-Ausbau Gleichgewichts. Diese Ergebnisse können nicht ermittelt werden anhand von Einphasen- und Totalspannungsmodellen. L’article s’intéresse au rôle méconnu de l’eau interstitielle dans le dimensionnement de tunnels profonds creusés dans des milieux poreux saturés. Des calculs adimensionnels par éléments finis soulignent l’influence des caractéristiques de l’eau interstitielle (pression in situ et compressibilité) ainsi que des conditions aux frontières (perméabilité du revêtement) sur les équilibres court et long terme de l’ouvrage. Ces résultats ne peuvent pas être obtenus par des calculs en contraintes totales.

Jan 1, 2003

By Michael Feroz

Severe drought in the Colorado River Basin over the past 10 years has caused water levels to drop in Lake Mead by more than 113 feet. The current lake level is at elevation 1,112 feet mean sea level (msl). Lake Mead is the primary source of water supply for greater Las Vegas. Water for Las Vegas from Lake Mead is accessed through two existing submerged intake shaft and tunnel systems. If the water levels continue to drop in the lake, the Intake No. 1 will become inoperable below water level elevation of 1,050 feet msl. To sustain the current levels of water delivery to all member agen-cies in the southern Nevada region, the Southern Nevada Water Authority (SNWA) has decided to construct a third intake at a deeper depth in the lake to ensure better quality water and enhanced reliability.

By David E. Swanson

The U.S. Bureau of Mines undertook a basic investigation of collimated abrasive water-jet behavior because a more complete understanding of the fundamental process may lead to further technical advances. Laboratory experiments used 2-mm water-jet nozzles and new entrainment apparatus to analyze collimated abrasive water jets operating under varied conditions. Maximum water pressure was 69 MPa to permit use of conventional hoses with a burst-to-operating-pressure ratio of 4. Nozzle and induction line pressures, abrasive induction rates, and jet reactive thrust forces were recorded for each operating condition. Average jet velocity and power were determined from component mass flow rates and reactive thrust force measurements. Relative velocity and cross-sectional distribution of abrasive particles were determined using impact analysis techniques. Other jet characteristics were determined photographically. Properties of free water jets, collimated water jets, and collimated air-water jets were determined for comparison.

Jan 1, 1989

By Sushant Upadhyaya, Deniz Karadeniz, Ahmed Mohamed

Soil setup analysis provides opportunities for efficiencies in pile foundation design and installation. Soil setup gain with time was evaluated as part of the foundation design and installation for twelve bridges along the Interstate 64 corridor between York County and Newport News in Virginia. The substructure elements of the bridges consist of driven precast prestressed concrete piles or H-piles. This case study describes lessons learned to understand the soil setup phenomenon during the installation of the piles in coastal plain. We were able to make expedited decisions during construction by analyzing previously performed pile dynamic analyzer (PDA) test results within the project alignment. Data evaluation included analyses of PDA data obtained from initial driving and restrike after a few hours to 5 weeks. The test data showed pile resistance increase up to twice in most cases and as high as four times in some cases. Foundation design and acceptance based on soil setup can provide opportunities for cost savings and advanced scheduling during construction.

By K. Holmberg, D. Herriot

This paper by Mr Mclvor is yet another contribution to the eternal controversy surrounding the benefits, or otherwise, of high circulating loads in closed circuit grinding. Throughout the paper it is difficult to establish whether the author is referring to effects relating to the mill, classifier, or to the overall circuit. Table 1 is put forward as indicating the advantage of operating at high circulating loads. From the two (it would be interesting to see more) product sizing points provided in each case, the conclusions to be drawn are that cases one and two have very similar size analyses. The third case, however, indicates a much flatter curve, that is to say, higher fines production and a very wide spread of size ranges. If the objective of this circuit is to provide a closely sized product with minimum overground slimes to the downstream process, then it would appear to be the less "efficient" by far. No data is given for product pulp densities either. The term "efficiency" should never be used without a careful and clear definition. In this case, "efficiency" is used to express an apparent percentage reduction in operating work index (Bond) from the measured "standard" at 250% circulat¬ing load operation. The Bond calculation is itself based upon

Jan 1, 1989

By Leeming. J. R.

In the UK, powered supports are normally salvaged from longwall faces on completion of production, for reuse on the next unit. Where a spare set of supports are held, the salvaged supports are often stored in underground roadways awaiting installation. One mine in the UK extracts a 5m section, and holds two sets of 2x950t powered supports, each weighing approx. 35t and having closed dimensions of 8m long, 2.5 high and 1.75m wide. As the first set would not be required for over 12 months, and because of space limitations below ground, it was decided that the supports would be left in situ, the district sealed, and reopened at a later date for support salvage. The paper described the decision making process, and the inertisation of the sealed district utilising nitrogen generated on the mine surface and piped to the point of use. The re-entry and re-ventilation of the district are also described. The paper then goes on to describe in more detail the discovery of a spontaneous combustion event that occurred in the waste behind the powered supports, and its treatment and control using extra nitrogen brought to the mine by tanker and introduced at strategic locations along the faceline via boreholes, leading to a successful salvage and re-sealing.

Jan 1, 2009

By Dale S. Preece

The computer program. DMC Qistinct Motion &de), which w&s developed for simulating the rock motion associated with blasting, has been used to study the intluence of row delay timing On rock mOtiOn. The munerical simulations correspond with field observations in that vmy short delays (< 5Oms) and vety long delays(> 3oOms) produce a lower percent-cast thao a medium delay (100 to ZOO ms). The DMC predicted relatio&lp between row delay timing and percent-cast is more complex than expected with a dip in the auve where the optimum timing might be expected. More study is required to gain a full undasranding of this phenomenoo.

Jan 1, 1994

By W. Dziurzynski

Transient states of the air parameters in mine workings occur as the effects of natural and technological disturbances, and in particular as a result of changes in ventilation conditions, caused by alteration of the mine workings geometry, state of fans performance or emission of gases. Particularly significant are those transient states caused by disturbances resulted from catastrophes, since they are frequently associated with violent phenomena that may be a danger for life and health of the staff working underground. The paper presents a number of examples of transient states of the air parameters in mine workings after a catastrophe, like the bump in the ZABRZE-BIELSZOWICE coal mine. Registration of air disturbances by the monitoring systems of ventilation in mine workings in the area of disaster both at the moment of a catastrophe occurrence and later during the rescue operation, enabled to track out the incident and identify the circumstances and reasons of those tragic events which caused death of 18 miners during last two years. Furthermore, computer simulations of processes occurring in mine ventilation network make effective research tools to be applied in practice, among others for the study of accidents and disasters.

Jan 1, 2003

By S F. Simmons, J Fleming

Alteration and mineralisation at the Island Copper deposit is related to the intrusion of Early Jurassic quartz feldspar porphyry dykes into surrounding comagmatic Bonanza volcanic rocks. The pyrophyilite alteration zone forms an upward flaring cone, largely hosted within a breccia body that cross-cuts the Co, Mo, and Au-rich ore shell. This alteration zone contains pyrophyllite, dumortierite and diaspore and resembles alteration occurring in some high-sulfidation deposits, but which is barren. Fluid-mineral equilibria and fluid inclusion studies indicate formation at approximately 300 ¦C from fluids dominated by steam and gases. These fluids appear highly acidic, but sulfur poor, leading to extreme base leaching within the breccia body and surrounding rocks.

Jan 1, 1995

By Roger K. McLimans, Venkatramaiah N. Vasudev, Christian Knudsen, Stefan Bernstein, Dirk Frei

Computer Controlled Scanning Electron Microscopy (CCSEM) analyses of sediment samples from coastal regions of Kerala and Tamil Nadu states and the heavy mineral deposits of Chavara, South India, show large lateral differences in the titanium content in ilmenite due to varying degrees of iron leaching. As the depositional environments for the sands with varying degrees of ilmenite alteration are comparable, the cause for the different degree of alteration is due to differences in the primary source of the ilmenite or to differences in the geochemical history of the ilmenite grains during transport from source to deposit. The CCSEM analyses of the heavy mineral fractions show that source of sediments with a high content of titanium-enriched ilmenites, mainly the heavy mineral deposit around Chavara, resides in the khondalite belt of South India (granulite facies metasediments). The less titanium-enriched ilmenites are sourced from other rocks in the area such as the charnokites. Those conclusions are based on the high MgO content in the leached ilmenites, chemical composition of the accompanying garnets (low CaO and high MgO), and the concentration of aluminum-rich minerals in the sands.

Jan 1, 2005

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

Jan 1, 1982

By W. E. Pittman

The Bureau of Mines, as part of its Health and Safety Technology Program, is conducting research on the use of ground penetrating radar (GPR) for mine hazard detection. GPR offers a possibility of mapping immediate below-surface geologic conditions, including faulting and other anomalies, thereby exposing potential safety hazards to miners. This report summarizes a literature review of the current status of GPR research in and outside the Bureau.

Jan 1, 1984

By Ji-He Wei

Keywords: stainless steel, AOD refining, side and top combined blowing, mixing characteristics, water modeling The fluid mixing characteristics in the bath during the side and top combined blowing AOD (argon-oxygen decarburization) refining process of stainless steel have preliminarily been investigated on a water model unit of a 120 t AOD converter. The geometric similarity ratio between the model and its prototype (including the side tuyeres and the top lances) was 1:4. On the basis of the theoretical calculations for the parameters of the gas streams in the side tuyeres and the top lances, the gas blowing rates used for the model have more reasonably been determined. The influence of the tuyere number and position arrangement, and the gas flow rates for side and top blowing on the characteristics has been examined. The results demonstrated that the liquid in the bath underwent vigorous circulatory motion during gas blowing, without obvious dead zone in the bath, resulting in a well mixing effectiveness. The gas flow rate of the main tuyere had a governing role on the characteristics, a suitable increase in the gas flow rate of the subtuyere could improve mixing efficiency, and the gas jet from top lance could make the mixing time prolong. Corresponding to the oxygen top blowing rate specified by the technology, a roughly equivalent and good mixing effectiveness could be reached by using six side tuyeres with an angle of 27 degrees between each tuyere, and five side tuyeres with an angular separation of 22.5 or 27 degrees between each tuyere. The relationships of the mixing time with the gas blowing rates of main-tuyeres and sub-tuyeres and top lance, the angle between each tuyere, and the tuyere number have been obtained.

Jan 1, 2005

By J. R. Thoenen

In June 1929 the Bureau of Mines issued a 13-page information circular entitled "Mineral Wool," which was one of the first publications to present to the public Rome technical aspects of the mineral-wool industry. Since then several articles on the subject have appeared in the technical press as well as in publications of State organizations. Inquiries for information on mineral wool have continued to be received by the Bureau of Mines in large number, and in 1935 it was decided to make a field survey of the plants then producing and to collect therefrom technical data to be compiled in a paper for nubile distribution. With the cooperation of the industry, this survey was made, and Information Circular 6984, Mineral Wool, was published in January 1930. The issue was exhausted after a few months, and requests for copies continued to come to the Bureau. As opportunity arose, further field studies were made in American as well as Canadian plants. The present circular contains the essential information in Information Circular 6994 together with date from later field studies.

Jan 1, 1939

By Ted Schwinden

It&apos;s my pleasure to welcome the Rocky Mountain Coal Institute to Montana. Now that you&apos;ve ended a 74 year history of meeting outside our borders, I hope you&apos;ll be back more often. Even if I can&apos;t convince you to come back before 2060, when another 74 years will be up, I&apos;m confident the Kalispell and Flathead Lake area will do the persuading for me. In recent weeks, I&apos;ve made a number of speeches around the state pointing out just how wrong the revenue projections in Montana&apos;s state government made in April of &apos;85 were when we came to April of &apos;86. Since the middle of this month, Montana&apos;s legislators have been in Helena struggling to balance a state budget that, by the end of fiscal year &apos;87, threatened to be some $88 million in the red. Other western states reliant on natural resource and agricultural economies have found themselves caught in the same deflationary spiral. The "window of opportunity" I proposed and the 1985 Montana Legislature passed, couldn&apos;t have been opened at a more difficult time. What was envisioned as an incentive to expand Montana&apos;s coal production, and our tax base, ran aground on low oil prices and excess hydroelectric power. De- spite the one-third severance tax rebate offered on new coal production, year-to-date figures published in the June 2nd Coal Week show that production in Montana is down almost 10 per- cent from last year. Again, we&apos;re not alone. Production in Wyoming is down 8 percent and in North Dakota, it has dropped 13 percent. An over- all 3 percent production decline in western states looks even worse when contrasted against a 12 percent increase for your eastern competitors. Montana&apos;s "window of opportunity" had the potential to be a significant signal to your industry. That potential was quickly tempered by the inability of Arab nations to stabilize world energy prices. If any of us had forgotten, the last twelve months have reminded western states that the well-being of our natural resource economies has a tremendous impact on the ability of all levels of government to provide services. The past year has also driven home that in the world of business and in the business of the world, risk-taking is still the name of the game. The Western Governors recognize the problems facing this industry - and our states - and we&apos;re prepared to fight for the future of western coal. In the past two decades, legitimate environmental concerns have created a vast body of new legislation affecting coal producers. The industry has been required to meet new reclamation standards - tough regulations relating to ground water, air quality and wildlife habitat. To the industry&apos;s credit, coal companies have hired professionals with the technical know-how to do it right. Rather than considering reclamation laws to be an unreasonable burden, today&apos;s coal company is more likely to view its reclamation efforts as a source of corporate pride. In a sense, the industry and the agencies which regulate it have matured together . . . although at times OSM is reluctant to admit that either of us capable of or willing to play by the rules. Certainly some abuses exist and OSM&apos;s oversight has been helpful in ensuring parity between those states willing to comply and those that would rather defy federal law. Nonetheless, penalizing the more modem and responsible western coal industry for abuses that occur elsewhere is both unfair and counterproductive. Federal penalties range from "cruel and unusual" reporting requirements to the proposed electricity tax that would effectively force utilities and ratepayers who have already met the sulphur emission standards to subsidize those who have dodged their cleanup responsibilities. As a member of the Alliance for Acid Rain Control, I have joined corporate leaders, academicians, environmental representa-

Jan 1, 1986