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By David Court, Rab Brown

The paper discusses the work in progress on the construction of the extension of the High Speed Rail line from the Channel Tunnel into the centre of London UK known as the “Channel Tunnel Rail Link” (CTRL), and particularly on contract 250 which involves the construction of two 5.3Km tunnels 7.15m diameter constructed with two EPB convertible tunnelling machines underneath the densely populated area of East London. In addition the paper will look at an innovative Alliance that has been formed between the Contractors and the Client’s Engineer involved in the construction of the London Tunnel Contracts

Jan 1, 2003

By Bernd Friedrich, Elif Emil‑Kaya, Merve Papakci

In the production of SmCo permanent magnets with excellent temperature stability, corrosion resistance, and oxidation resistance, samarium (Sm), one of the rare earth elements (REEs), and cobalt (Co) are employed. Cobalt (Co) is a crucial component in tool materials, nickel-based alloys, tablet and smartphone batteries, and electric car batteries. REEs and Co have been listed as critical raw materials by the European Union Commission for many years. Due to the ever-growing demand for Co and REEs in technological applications, the recovery of these elements from secondary sources has garnered significant interest. There are two types of SmCo magnets, one of which contains a high amount of iron, approximately 15.2%. This paper focuses on the recycling of Fe-bearing SmCo. In this study, an oxidative leaching process with nitric acid was developed to eliminate iron through in situ hydrolysis and to dissolve REEs and Co. The influence of experimental conditions on the formation of an amorphous iron compound through the hydrolysis of Fe3+ in a nitric acid environment was thoroughly examined based on a Taguchi orthogonal array. The optimal parameters for oxidative leaching were determined to be an acid concentration of 3 mol/L, a solid-to-liquid ratio of 1/10, and a process temperature of 60 °C.

Feb 15, 2024

By D. Einarson, B. Strickland

The decision to accelerate development of Stillwater Mining’s East Boulder Mine was made in March of 1998. It required the completion of conceptual designs by July of 1998. This was accomplished through teamwork and close cooperation of mine personnel, engineering firms and vendors, all working toward the common goal of developing an efficient and workable design. Early in the project, representatives of Stillwater Mining, Kilborn International, Parsons Brinckerhoff Transit and RailSystems, Continental Conveyor, and H.A. Simons met to develop methods to bring the mine into production at a highly accelerated rate and to solve potential bottlenecks, including the movement of personnel, materials, and muck through a 5.6 km(3-1/2 mile) adit. This interaction, including companies not normally associated with the mining industry, led to innovative approaches and designs produced by Kilborn Engineering and Stillwater Mining.

Jan 1, 1999

By L. Vinnett, J. Yianatos, S. Flores

"A numerical conditioning analysis for mineral recovery estimation was performed for industrial flotation plants, considering the copper (Cu), molybdenum (Mo) and iron (Fe) separability. A modified relative condition number, ?, was presented that allowed sensitivity analysis to be evaluated for the component recovery by means of an analytical formula. This closed form made it possible for the error propagation to be determined from feed, concentrate and tail grades with different orders of magnitude. The ? parameter can be evaluated using available grade data from the design criteria or historical mass balances, in which the variability is typically unknown. Reconciled data from different Cu/Mo concentrators were employed to evaluate the effect of small numerical disturbances in the grade data on the mineral recovery estimation. Higher error propagation was typically observed for Fe. The Mo minerals presented numerical problems, mainly in second cleaners and in the first cell of rougher banks. Lower condition numbers were observed for Cu due to the higher flotation rates.Mass-balance data reconciliation without redundancy was evaluated for a typical Cu/Mo flotation circuit using relative error minimization. Significant relative errors in the mineral recovery estimation were obtained with nonreconciled data in ill-conditioned problems. Negligible improvements in the mineral recovery estimation because of the data reconciliation with regard to the nonreconciled approach were obtained in well-conditioned problems. In addition, the improvements in mineral recovery estimation by using Cu, Mo and Fe in the data reconciliation were nonsignificant with respect to using only the best-conditioned component in well- and ill-conditioned problems.Despite the effort in data reconciliation and data repetition, poor performance may be obtained in ill-conditioned problems, which can deteriorate the flotation rate characterization. The error propagation has a negative impact on the mineral recovery of the first cell, which may significantly bias the flotation rate characterization of both valuable and nonvaluable elements.IntroductionMass balances have been extensively used in flotation processes to determine the mass flowrates (production) and mineral recovery (efficiency) of valuable minerals. Simple relationships for steadystate processes based on the feed, concentrate and tail grades can be obtained by taking a black-box approach. However, the calculation of concentrate flowrates from different components of the system, such as size fractions, chemical elements or minerals, does not satisfy the mass-conservation principle because of measurement errors (Smith and Ichiyen, 1973; Romagnoli and Sánchez, 2000). Mass-balance data reconciliation allows for obtaining a unique solution that satisfies the total and component mass balances, making small adjustments to the process data and taking advantage of the information redundancy (Narasimhan and Jordache, 2000). This methodology, which is based on a constrained weighted least-squares minimization, has proved to be robust when measurement errors are normally distributed, in the absence of gross errors.Commercial software has been developed to conduct massbalance data reconciliation in flotation processes, including MATBAL (Algosys, 2002), BILMAT (Algosys, 2013), JKMultibal (JKTech, 2013), BILCO (Caspeo, 2013) and HSC Chemistry (Outotec, 2013), which accomplish the reconciliation using known data accuracy in the optimization problem. The data accuracy can be obtained by sampling a stream n times in a run, known as repeats, each with independent chemical assays. Some unmeasured variables can be estimated using the measuring redundancy and sensor location. At present, grade and flow rate sensors may be incorporated in flotation to conduct real-time mass balances. However, a lack of sensor calibration and maintenance for suitable online measurements hinders the quality of the information. In"

Jan 1, 2016

A virtual reality approach is presented that can aid entities such as mining companies and land use planners in communicating a visual understanding of a mining operation to interested stakeholders, citizens? groups, and public committees. These visualizations are particularly useful in permitting, production planning and mining closures, contributing to accurate communication and evaluation of mine plans, ultimate land use and evaluation of potential design options A case study is presented, that was created using commercially available virtual reality tools, to emphasize the benefits of visualization technologies in the sustainable development of mineral resources.

Jan 1, 2003

By M. D. Ballain, V. C. Storhok, B. Pesic, J. C. Sever

Northwest Alloys, a wholly owned subsidiary of Alcoa, produces magnesium from dolomite by reduction with ferrosilicon and aluminum. This process produces alkaline by-products in quantities that allow their consideration for use as commercial by-products. Two such products are dicalcium silicate slag, Di-Cal, and magnesium oxide condensate, MgO. The alkaline properties of these materials offer acid neutralizing capability comparable to the traditionally used lime, therefore, warranting a study for their use in applications where the neutralization of acidic waters or process solutions is required, such as treatment of mine waters. In this ongoing study, three mine waters (Bunker HillMine, Berkeley Pit, and Blackbird Mine) were selected for treatment with Di-Cal and MgO. Lime was used as the background control. The solid precipitates were subsequently contacted with pure water at four different pH conditions for stability testing of prepared metal precipitates (expanded TCLP). It was found that neutralization with Di-Cal results in precipitates which are of equivalent to superior stability than those from lime treatment.

Jan 1, 1999

By W. D. Eddy

Topaz is a fluorine-bearing aluminosilicate mineral of the kyanite-sillimanite group. The formula has been given as Al2SiO4(F,OH)2, [Al(F, OH)]2SiO4, or 2Al2O3?2Al(F, OH)3SiO2. Topaz is generally considered a semiprecious-to-precious gem mineral, but it is a fairly common minor constituent of granites. In 1937 the U.s. Geological Survey reported an occurrence of massive topaz in the 3 Brewer gold mine, Chesterfield County, S.C. Over the next 8 years considerable research was done on topaz to establish its properties and to determine possible end uses The first reported shipment of ore was in 1939 Peak production was reached in 194412, and output then began declining until the mine closed in 194913? During World War II topaz was used in refractories, as a flux in steel mills, and in the manufacture of borosilicate glass 14. The main advantage of using topaz over kyanite and sillimanite in refractory use was that calcined topaz converted to over 95 percent mullite (3A1203 .2Si02) while calcined kyanite or sillimanite contained only 88 percent mullite15. However, a major draw-back to utilization of topaz is the evolution of fluorides during calcination. In 1973 the Geological Survey reported that topaz occurred in probable commercial quantities in at least two domestic locationsl6: the Brewer area of South Carolina and a location in Colorado. The literature also indicated that progress had been made in controlling fluorine-bearing fumes. This research has progressed to the state where valuable fluorine compounds are being recovered on a commercial scale 17. Thus, a major obstacle to utilization of topaz appears to have been resolved. The Bureau of Mines under its program of advancing minerals technology initiated a project to study techniques for the concentration of topaz from disseminated materials. The objective of the study was to determine those techniques that would be used to produce topaz concentrates that could be utilized as a source of fluorine and mullite.

Jan 1, 1977

By S. Maurigiannakis

In an effort to promote sustainability in the construction industry, the natural decorative stones that cover large external areas of buildings may be replaced with artificial stones. In this paper the physical and mechanical properties of artificial decorative stones are presented and are critically compared with corresponding natural stones. To test suitability for various applications, artificial stone specimens were subjected to weathering testing (freezing-thaw cycles in a climatic chamber). Mechanical characterization of these specimens was based on uniaxial compressive testing as well as non-destructive ultrasonic testing. Preliminary results show that artificial stones can replace natural stones, thus creating a sustainable development option for the construction industry.

Jan 1, 2003

By Mark A. Koestel

Cobalt-sulfide mineralization can he found in potentially economic quantities where permeable, basal Cambrian formations "pinchout" against Precambrian pal eotopographi c highs. These environments are common around the Saint Francois Mountains of southeastern Missouri and they share many similarities with the geologic environments of Zambia and Zaire in South Africa. Exploration for this type of deposit involves test drilling targets identified by trend analysis from past drilling, geophysics, geochemistry and a comprehensisve study of regional geology and isopach maps. Innovative ideas, new exploration concepts and insoluble residue geochemical methods may provide the necessary "edge" needed to complement basic geologic understanding leading to ore discovery.

Jan 1, 1987

Improvements in computer technology and associated software have allowed the improvement and development of more advanced ventilation modeling software packages including those that have the ability to simulate the effects of a mine fire on the ventilation system in terms of heat, smoke and gas distribution. This ability has real applications for the mining industry in terms of emergency planning, training and response. The primary focus of this paper will be the benefits to training programs that this type of software can provide to all types of training for various personnel, from the newly hired inexperienced miner, mine rescue, atmospheric monitoring personnel and emergency evacuation drills. The results of the simulations can then be used to give miner?s more detailed information on what types of conditions they may face based on the type and location of the fire and the program itself can be used to manipulate the ventilation system in a way that emergency response personnel may (i.e. tear down stoppings to reduce airflow to the fire area) and see the effects in real-time.

Jan 1, 2012

By John Barakso

The Sam Goosly or Equity silver deposit is fundamental- ly a discovery based on the analysis and interpretation of reconnaissance geochemical samples. The discovery was made by Kennco in an area of heavy forestation and wide- spread cover by thin glacial debris. No major mines had been discovered in the vicinity of the discovery prior to the geochemical reconnaissance, and the interpretation of the geochemical results therefore was based on data available through geologic mapping and the sample collection process. In the period 1959-1961, PE. Hirst and his crew, in 1962- 1965 P.T. Blackand his crew, and in 1966-1967 C.S. Ney and P.T. Black and their crew collected geochemical samples from the area of what is now the ore body. Several of these samples were compiled and reanalyzed in the winter of 1966- 1967 for various trace elements, including fluorine. A strong, almost 16-sq-km (10-sq-mile) fluorine anomaly was projected along with a very weak heavy metal anomaly. On the basis of this anomaly, a chalcopyrite-bearing quartz monzonite was discovered in 1967. This was a misleading, noneconomic discovery not associated with the Sam Goosly discovery. The interpretation of the geochemical data by Barakso that summer indicated that another source was responsible for the fluorine anomaly. The conclusion was based on the assemblage of trace elements. Therefore C.S. Ney recommended further regional soil sampling to check the original data. The early results of this follow-up sampling found over 33 ppm silver. First float, then ore outcrop was found in the area of the silver anomaly. The attached reprints complete the development of the property after the discovery of the outcrop of ore.

Jan 1, 1990

By Theophilus Mensah, Kwame Awuah-Offei

Engineers face significant challenges when determining what geometry provides the most profitable and safe stope for extraction. Several techniques and optimization algorithms have been developed in recent years, but most fail to find optimal solutions because they are heuristic or LP-based without efficient geometric constraints. This paper presents a two-dimensional binary linear programming (BLP) model for determining the optimal combination of blocks in a stope that maximizes the economic value of the layout of stopes for a sublevel deposit. The work draws from Queyranne and Wolsey’s (2017 & 2018) formulations of tight constraints for bounded up/down times in production planning problems to formulate novel and efficient geometric constraints along with geotechnical and grade constraints for the BLP stope layout optimization problem. Results from the model indicate that it is possible to formulate efficient shape constraints in LP-based approaches. The model used for the numerical example contained 144 valuable blocks out of 774 blocks, which translates into an economic value of $53.21M. The BLP model selected 60 valuable blocks and 13 waste blocks that met all constraints translating into a maximum economic value of $34.4M in 1.83 hours within a gap tolerance of 0.00%.

Jun 25, 2023

By N. Moelans, I. Bellemans, K. Verbeken

Metallic droplets can remain attached to solid particles within liquid slags, resulting in production losses in several movement of solid particles in the liquid slag in a system, considering the attachment of liquid metal droplets to solid slag and on the resulting microstructures is investigated as a function of the velocity of the particles. For all wetting For the amount of metal attached to the particle, a clear trade-off was found between the speed of motion of the solid particle and the wetting regime.

By Rolph Linder

It is generally known and accepted that the efficiency of the blast furnace process, expressed by the symbols specific production and coke consumption, is influenced by a large number of variables connected to the type of burden, the alloy contents of the produced iron and the conditions of production as composition and preheating of the blast, the furnace heat losses and the possible use of fuels added on the tuyere level. It is furthermore obvious, that the coke consumption of the process will be influenced by specific production which could be said to be the result of two counter-acting influences. With high production, realized through intensive blowing, the passage time of the ore through the furnace is shortened leading to a decrease of the indirect reduction taking place in the upper part of the shaft within the temperature range of 300 to 1000°C. Simultaneously the external heat losses (constant in time) will be smaller calculated on each ton of iron and the resulting change in coke consumption will be the effect of both those influences. It is certainly of interest to be able to predetermine the effect of those variables before a change in the production practice is carried out.

Jan 1, 1964

By B. Pina

The conversion of maf coal to pyridine solubles and gas was investigated in a microautoclave batch reactor for two Kentucky washed coal samples (Ky. #9 and Ky. #11). Solvent hydrogen donor strength was controlled by the tetralin content of a mixed 1-methyl naphthalene-tetralin solvent. Primary liquefaction conversions greater than 90% in 10 minutes of reaction time at 427°C were achieved in liquefaction solvents with moderate hydrogen-donor strength (circa 40% tetralin). A modified irreversible first order rate expression, containing a parameter (a) to account for the intrinsic reactives of the maf coal, described the experimental kinetic data rather well. The integrated form of this rate expression is -k1e x = a (a- ß)e (eq. 1) Parameter ß in equation (I) is the pyridine solubility of the starting maf feed coal, x is the primary liquefaction fractional number of conversion, k1 is the specific reaction velocity constant and ? is reaction time. Primary liquefaction rate was found to be quite temperature sensitive and independent of coal when a liquefaction solvent containing 40% or more tetralin was employed. Primary liquefaction rate appears to depend on liquefaction solvent hydrogen donor strength for solvents containing = 40 wt.% tetralin. The intrinsic reactives in the maf feed coal or a appear to depend mainly on the inertinite group maceral content of the coal for the two coals studied in liquefaction solvents containing 3 40wt.% tetralin. In contrast, a appears to decrease in liquefaction solvents of low donor strength., i.e; solvents with less than 40wt.% tetralin.

Jan 1, 1984

By S. M. Hossaini, M. Ataei, H. Moosavi

The abstract highlights the importance of pillar stability in underground coal mines and the influence of rock mass strength and joint orientation on pillar behavior. The study employs numerical modeling using the distinct element code (UDEC) to investigate the impact of these factors on pillar stability. The research considers different joint orientations and varying rock mass strengths, analyzing parameters like stress distribution, displacement, and failure patterns. The findings reveal that both joint orientation and rock mass strength significantly affect pillar stability, with specific combinations leading to reduced safety factors and increased deformation. The study concludes by emphasizing the importance of considering these factors in pillar design for safe and efficient mining operations.

Apr 4, 2022

By Charles R. Boardman

Recent underground nuclear tests in tuff, alluvium, salt, and granite have yielded data essential to the evaluation of mining applications of contained nuclear detonations. The data indicate that for these media the cavity radius is predictable within ±20% without regard to the properties of the rock in the immediate shot environment. Properties of the chimney of broken rock resulting from collapse of the cavity, on the other hand, are found to be related to the properties of the rock and its preshot structural weaknesses. Seismic effects and radioactivity distribution are sufficiently documented to serve as a basis for predicting the safety conditions associated with detonations for a variety of yields.

Jan 1, 1964

"How Wall Street Darling Molycorp Undermined the U.S. Economy, Degraded our National Security and Distorted the Global Economic Balance and How These Falsehoods Continue to be Promoted Even Today INTRODUCTION & SUMMARY In 2007 the Molycorp Mountain Pass rare earth mine was resurrected from its desert-grave in California by its then-owner Chevron Mining. Responding to elevated rare earth prices Chevron began processing on-site rare earth concentrates left over from past mining operations that were terminated in 1998i. Chinese demand had sparked what was being described as a commodities super-cycleii. Commodity prices were on the move. Wall Street smelled opportunity. In 2008 Goldman Sachs, Pegasus Partners, Resource Capital Funds, Traxys North America LLC and Carint Group LLC acquired the mining assets from Chevron. In an environment of ever-declining ethical standards and regulatory consequences the private capital group and their investment bankers would bring Molycorp to market. Molycorp, with its high powered investment banking team of Morgan Stanley and J.P. Morganiii, easily dominated the contest. Molycorp promoted itself, largely based on its past operating history and proven reserves, as the best company to challenge China’s monopoly control over the production of rare earths: a group of elements critical to most advanced technologies and U.S. defense systemsiv. Most of Wall Street’s hottest investment sectors were dependent on these materials: alternative energy, green technologies, computing, personal communications, advanced electronics and defense systems. By late 2010 there were dozens of prospective rare earth start-up ‘mining companies’ seeking capital. Eventually the number of prospective rare earth mining companies seeking capital exceeded 400, despite the reality that supply requirements of this market were disproportionally small when compared to other natural resource sectorsv. In the world of finance ‘smart money’ picks the winners. Consequently just twovi projects attracted nearly all of the capital (Molycorp and Lynas). Wall street picked Molycorpvii. This paper will primarily focus on Molycorp. By early 2010 the words “Molycorp” and “Rare Earths” electrified many people in the mining industry, most non-Chinese manufacturing technology companies, U.S. & allied defense contractors, technocrats in the U.S. national security community and eager investors across most of the world’s stock markets. It was the hottest story of the yearviii. The financial, technology and defense press coverage verged on euphoric: heaping fuel on fuel until the highly combustible Molycorp-pyre cast a long shadow over all of its rivalsix. When the IPO match was lit the spectacular flaming pyre sucked all of the oxygen out of the rare earth spacex. Molycorp was ranked the most lucrative IPO of 2010, resulting in record breaking profits to its private investors and massive returns for its early stock holding investors."

Jan 1, 2017

By Baolin Qu, Jingxin Wang, Cuncang Xu, Bing Wu, Mingyu Zhong

With the development of the coal mine regulation regime, the situation of coal mine safety production in China has continued to improve. However, coal mine accidents have not been fundamentally eliminated; constantly learning from historical accidents can make mining work safer. Therefore, to better understand the coal mine accident characteristics, this study analyzes the tendency of coal mine safety accidents from multiple perspectives, among which all accidents after the establishment of the State Administration of Coal Mine Safety in 1999 are the top priority. The results show that strict national policy, technological progress, and reasonable coal prices are conducive to the safe development of mines. On the contrary, high-intensity centralized production will lead to frequent accidents in the peak season of coal production. In addition, the type of coal mine ownership will have an indirect impact on the occurrence of coal mine accidents. The research results not only play a positive role in the prevention and control of coal mine accidents in China but also have reference meanings for the safety production of coal mines in other countries in the world.

Dec 28, 2022

By Dennis C. Martin

Assessment of the potential for mining induced subsidence and determination of ultimate design requirements for a mining operation should be based on a number of assessment approaches. Although the rock mechanics engineer has a variety of limit equilibrium and numerical modeling tools available for assessment and prediction of subsidence effects, empirical approaches based on precedent experience provide a powerful tool for calibration/verification of analytical models and prediction of subsidence. Three separate analyses approaches have been applied to the assessment of potential subsidence for a proposed block caving mine in eastern Canada. The investigations have included an assessment of documented historical information from previous block cave mining at the site, deterministic analyses using limit equilibrium approaches to assess kinematically possible failure mechanisms, and three-dimensional numerical modeling techniques. Analyses results have been used and compared with precedent experience and documentation of subsidence behavior from previous mining to optimize the subsidence predictions for the proposed mine.

Jan 1, 1998