Search Documents

By Ralph M. Stricklen

The need to move large tonnages of slurry has grown as mines have become larger. As existing tailing depositories are filled up, new mines developed, or environmental requirements dictate, it becomes necessary to transport tailing particularly over longer distances. A typical slurry transport system is shown in Figure 1A. Figures 1B, 1C and 1D show sketches of the system auxilliary components: feed box, receiving sump and drop box, respectively. There are two basic types of slurry transport systems, packed flow and slack flow. Packed flow is typified by a pipe running full; slack flow by a launder or pipe running less than full. Slack flow in launders or channels is also referred to as open channel flow. Generally slack flow slurry transportation involves a flow with less than 65 per cent solids, and there is an upper limit on particle size, depending on the slope of the system.

Jan 1, 1984

By C. M. Chang, H Gu, J. A. Barrera-Godínez, T. J. O’Keefe

The inability to economically separate Fe3+(aq) from a variety of liquid effluents is a major Concern for the primary metals industry. A unique solvent extraction process, galvanic stripping, has been developed to address this problem. The galvanic stripping of iron from D2EHPA using only a 5~10 g/L H2SO4 solution is achieved after Fe3+ is directly reduced to Fee, in the organic phase using zinc metal additions. To date, the primary focus of the laboratory research has been on optimizing the parameters that control iron removal. The results from these studies have now been, used to make a preliminary design for a continuous flow process that is envisioned for zinc industrial applications. Specific quantitative data are shown for the use of a Zn-Ph cellos° in the iron-reams al process. Some introductory results on electrochemical potential measurements and impurity distribution with solution cycling are also giiven.

Jan 1, 2000

By P. V. R. Bhaskar Sarma, P. K. Sahoo, G. Roy Chaudhury

A process was developed to treat an ammoniacal leach liquor containing zinc using Di (2-ethyl hexyl) phosphoric acid (D2EHPA) as the extractant. The objective of this work was to develop a process package for the treatment of complex sulfide leach liquors. Zinc extraction could not be carried out directly from the ammoniacal solution in mixer-settler units because of crud formation and low extraction efficiency. After neutralizing the free ammonia with H2SO4, the extraction efficiency was only about 40%, due to the high concentration of (NH4)2SO4. To decrease the (NH4)2SO4 concentration, the free NH3 was steam stripped, and the resultant liquor was subjected to zinc solvent extraction. An extraction efficiency of 98% could be achieved by controlling the equilibrium pH. Stripping studies were also optimized after removing ammonia from the zinc-loaded organic. A continuous 100-hr operation that included extraction, scrubbing and stripping, was carried out successfully.

Jan 1, 1995

By Charles Schmidt

Phalabonva (Figure 1) is situated in the northern province of South Africa adjacent to Kruger National Park, about 500 km from Johannesburg. The nearest South African port to Phalaborwa is Richards Bay about 700 km distant by rail.

Jan 1, 1999

By George Biro, Christoph Mueller

A number autonomous operations is in place in several, mainly in fenced areas, where safety is assured by locking off the entire area for other traffic. However autonomy can be brought much further if functional safety is assured and a real mixed traffic of autonomous and manually operated vehicles is possible. MobileTronics has created a modular software and control framework for autonomous machines. The paper covers application examples in which the deterministic object recognition in combination with probabilistic algorithms and sensors is used as a basis for functional safe certification of mixed traffic autonomy.

Jun 25, 2023

By D. Duvris

The main objective of this work was to quantitatively investigate exhaust emission levels relative to maintenance (service) intervals during the operation of diesel-powered equipment at an underground bauxite mine in Greece. Such emissions depend on a great number of parameters, including the type of engine (technology) and its tuning, the type of work performed (as related to the engine workload), the suggested maintenance intervals, the altitude, the temperature and humidity of the atmosphere in the underground mine, the properties of the fuel and the operator's training and experience levels. The necessary ventilation quantities were calculated based on exhaust gas-concentration measurements and site-specific relationships between pollutants and adjusted air-quality indices. Diagrams comparing the necessary and recommended airflow for several equipment groups, featuring two engine types and different maintenance intervals, are presented.

Jan 1, 2000

By Daniel G. Ganey

Kerr-McGee Coal Corporation has used diesel face haulage and support equipment at its dual-seam Galatia Mine in Southern Illinois since production activities commenced in 1983. The mine began production from its lower seam, the Harrisburg No. 5 coal seam, in October 1983 and from the upper Herrin No.6 coal seam in April 1985. Before production began, the company developed a program designed to make use of the flexibility offered by diesel equipment. While productivity was an important goal, the top priority of the program was to provide a safe and healthy work environment for the miners. Management believed that high productivity would naturally follow. History has proven this belief to be true.

Jan 1, 1990

By Andrea Brickey, RICHARD AMOAKO, Akshay Chowdu

Production forecasts derived from the medium-term schedule represent the best path forward for underground mining operations to achieve corporate and operational goals. Unforeseen circumstances, such as equipment breakdown, can cause significant deviations from established production forecasts in the short term. Such situations require timely mitigation of the effects of the deviations in order to stay as close as possible to the medium-term plan. This paper presents a deterministic mathematical formulation for short-term scheduling that addresses this challenge. The formulation is able to make up for deficits resulting from operational disruptions by minimizing deviations from medium-term production goals and medium-term activity start dates. We demonstrate this in a case study by simulating disruptions involving reduction in ore extraction capacity and development advance rate. Aside from the rescheduling capability, this formulation can help mine planners conduct analysis on the impact of various disruptions on the schedule. The formulation can help identify those conditions or disruptions that are more detrimental to the achievement of forecast targets, or otherwise. The formulation also affords mine planners the flexibility to prioritize one production goal over the other, depending on operational conditions at the mine. In the future, we seek to incorporate in the formulation respirable dust, diesel particulate matter and ventilation constraints in order to create more realistic schedules, and enhance miners’ health and safety.

Jan 1, 2024

By K. Häge

"Die Nachhaltigkeit der Braunkohlengewinnung in der öffentlichen Wahrnehmung wird nur weiter erfolgreich kommuniziert werden können, wenn durch konkretes Handeln glaubhaft gezeigt wird, dass die offenen Fragen fair und solide beantwortet werden. Dazu gehören insbesondere die neue innovative technische Lösung sowie das sensible Interessenmanagement. Die Braunkohlenindustrie hat gelernt, dass Offenheit und nicht zuletzt das beständige Bemühen um den Meinungsaustausch mit ihrem Umfeld wichtige Elemente sind. Der in Jahrzehnten erworbene Schatz an Glaubwürdig-keit ist eine Basis, auf der die Braunkohlenindustrie ihre Zukunft gestalten kann. Darüber hinaus sind politische Rahmenvorgaben erforderlich. Das öffentliche Interesse an einer sicheren und preiswerten Energieversorgung unter Einschluss der Braunkohle ist unverzichtbar. In diesem Kon-text kann dann die Braunkohle die an sie gerichteten Fragen der Ökonomie, der Ökologie und der Sozialverträglichkeit auch mit Hilfe von Indikatoren beantworten.ABSTRACTThe discussion of the sustainability of lignite mining can only be continued successfully if the indus-try acts in a practical manner and demonstrates trustworthiness by responding fairly and reliably to open questions. This includes new and innovative technical solutions as well as the sensitive management of interests. The lignite industry has learned that openness and the constant effort to exchange viewpoints within their environment are all essential elements. The credibility that has been gained over the decades is the foundation on which the lignite industry can build its future. Beyond that a framework of political guidelines is necessary. Public interest in a secure and inex-pensive energy supply that also includes lignite is indispensable. In this context, the lignite industry will then be able to answer the questions which are directed at them and concern the economy, ecology, and social tolerability also by indicators."

Jan 1, 2005

By B. A. Hancock

New permit discharge standards instituted at Hecla Limited?s Lucky Friday Mine required installation of water treatment plants to manage water quality at two outfalls to the South Fork of the Coeur d?Alene River. The 002 Outfall Water Treatment Plant (WTP) is a clarification-filtration plant for treating the combined mill and underground discharge water flows. Process optimization efforts were a significant challenge until the negative impact the exploration diamond drilling products had on the clarification process was identified and resolved. The products were being wasted directly to the mine water discharge system which was pumped to the surface WTP. Anionic soluble oil and polyacrylamide based products were causing TSS particle hydrophobicity and dispersion that greatly affected coagulation and flocculation response, resulting in excessive chemical usage and treatment control issues. This paper details how problems associated with the drill products negatively impacted the 002 WTP and how system changes, alternative product usage and treatment at the source resulted in more consistent plant performance.

Jan 1, 2011

By Thomas M. Tharp, Mark A. Travers

A new method is presented for precracking three-point bending specimens for fracture toughness testing. A notched specimen of rectangular cross section is placed on a flat loading platen, with paper between specimen and platen. The specimen is loaded from above through a roller placed directly over the crack. The thin, high compliance joint between specimen and platen causes a distributed load on the bottom of the specimen. This results in bending at the cracked section and crack initiation at the notch tip. Since the joint is thin, its stiffness increases rapidly with deflection and crack propagation in the specimen generally remains stable and controllable. Fracture toughness KIC in a sandstone directly overlying the No. V coal was measured to be 0.27 MPa m 1/2. Even for cracks 1 cm long this value of KIC results in substantially lower effective tensile strength (modulus of rupture) in roof beams than is expected from intact rock strength.

Jan 1, 1986

By S. Saklar, i. Bayraktar

The effect of the feed size distribution on the kinetic parameters in pyrite flotation was studied. The kinetic parameters of the particular sizes were determined as a function of whether other particle sizes were present. From the data, a relation between the pyrite flotation rate and the particle size distributions was obtained. It was shown that the flotation rate constant (k) is a function of the size modulus (dt) of the Gates-Gaudin-Schuhmann distribution, and its variation may be expressed as k = a • exp(b . d,) for either individual size fractions or composite feed. Parameters a and b are dependent on the particle size distribution of the feed. Specifically, parameter a increases linearly as the distribution becomes coarser. The above relationship was also tested under conditions in which the collector (KAX) dosage was varied from 130 to 278 g/t. It was shown that the established relation was not dependent on the collector dosage.

Jan 1, 2002

By B. Das, D. D. Mishra, M. I. Ansari

Experiments conducted with a 75-mm-diem hydroryclone have shown it is possible to obtain an iron ore concentrate containing 60% Fe. 2.65% SiO2, and 4.0% Al2O3 from Barsua iron-ore washing-plant slimes. About 60% of the iron values are recovered from slimes containing approximately 49% Fe, 8.9% A1203 and 11% SiO2. The obtained products can be used in the sinter feed for iron and steel making. The key to achieving process success lies in establishing the correct cut point (d50) of the hydrocyclone through the manipulation of operating and design variables, such as spigot and vortex finder diameter, solids concentration and operating pressure. The cyclone efficiency is represented by the partition curve. The cyclone performance, evaluated mathematically from the reduced efficiency curve, is represented by the equation Y = 100[1 -exp(-axb)], where: •X = did 50, •Y = corrected of efficiency (%) and •a and b are constants.

Jan 1, 1994

By Gordon S. Thomas

The problem of how best to exploit a reserve has vexed mine planners and design engineers since mining began. The cyclic nature of the mine design-scheduling problem, combined with the lack of good mathematical tools for tackling it, have ensured that it has been, and will continue to be, a major challenge for operations researchers working in mining. This paper reviews the current state of the art in pit optimisation and scheduling algorithms. Starting from the inception of the first block models in the late 1950's, it progresses through the developments and applications of the Moving Cone algorithm, the Lerchs Grossmann 3D Graph Theory algorithm and some of the heuristics, to the new artificial intelligence techniques that are being applied today. Along the way, it discusses the limitations of the various approaches and lays the foundations for the research that is currently being undertaken by CSIRO and others in the field of mine production scheduling and control.

Jan 1, 1996

By Randy Fulton, Ignacy Puszkiewicz, George H. K. Schenck

Stuart Olson Construction, Inc. excavated 385m (1263 ft.) long twin tunnels with 6.25m (20.5 ft.) O.D., a portal and a cross-over for the Edmonton, "Metro". The work for Contract No. 76458, SLRT South Tunnel and Portal, in Edmonton, Alberta, Canada was performed in 1989 and 1990. NATM was specified because of the instability of glacial deposits. The contractor decided to use "two firsts" on this project: Fully mechanized NATM and a novel excavator¬mounted tunneling machine. An excavator was equipped with a cutter boom, and a loading and conveying system. This novel machine cost only about one-third of the price of a special NATM roadheader. This new combination of NATM and an excavator-mounted cutter boom offered a cost-effective alternative to shields, slurry TBMs and roadheaders for short tunnels in unstable ground. For NATM tunneling in hard rock or in mixed faces, the roadheader-type cutter boom can be replaced with an impact hammer (hydraulic breaker).

Jan 1, 1993

By Karen L. Menna

At Digital Equipment Corporation, increasing demands on executive secretaries to share, track, and retrieve information prompted development of ALL-IN-1 System for Executive Services. Executive secretaries asked engineers to combine word processing and electronic mail with utilities for managing time; logging and tracking telephone calls, letters, and inquires; creating presentations; compiling directories; and archiving. The system, two years in development, now automates the president's and senior vice presidents? offices at Digital. It allows secretaries to interrupt any task with two keystrokes, and return later to the original task. The system has speeded customer response, enabled online information sharing, and increased professionalism and customer satisfaction.

Jan 1, 1989

By Rolf Pollak, Jan Tegtrneier, Gerhard Keller, Horst Gerhardt, Wolfgang Müller, Dieter Tetzner

INTRODUCTION Under certain geological and mining conditions mining near the surface results in an intensive destruction of the overlying rock strata. If the system of mine openings remains filled with air after having completed all mining activities because the flooding of the mines depending on the morphology of the mining area does not exceed a certain level, this circumstance might result in dangers for the public. This is particularly true where uncontrollable air- ways occur within the destroyed rock or if former uranium mining areas are concerned. In these areas radon emanation resulting in undue radon concentration should be taken into account. This circumstance can be counteracted by suitable measures of ventilation. In the following the example of a uranium deposit in the Erzgebirge Mountains (Saxon Ore Mountains) is used to illustrate how statements about the ground flow through overlying rock can be made on the basis of systematic investigations. Finally comparisons with experience gained in coal mining yield orientation data which are used as input quantities in ventilation network calculations and in project preparation of mine fans. Last not least it is proved that endangering the population by radon can be excluded by installing an appropriate fan. INITIAL SITUATION From 1946 to 1989 the uranium deposit of Schlemal-Alberode was mined starting from superficial zones down to depths of 1,800 m. The total output amounted to 80,000 t of uranium, i.e. Schlemal Alberode is one of the largest uranium deposits in the world. The mine openings comprise a cavity of 40 million m3. Al- though thin seams (0.2 to 0.3 m) and steep to semi-steep veins (60 - 70 degrees on average) were extracted using the method of overhand cut-and-fill there were also deposit sections with larger thicknesses and poor ore zones, respectively, where especially after the war until about 1955 large openings were formed due to missing filling. Due to this uncontrolled, relatively "wild" mining considerable subsidence of the surface and fractures in the border zone of the subsidence area occurred. The town of Oberschlema was destroyed and an area of 0.14 km2 was damaged by mining involving a maximum subsidence of 6 m in the centre - called deformation area. The rehabilitation work for the deposit area of Schlemal Alberode involves the flooding of the openings up to a level of the Markus-Semmler-Sohle as long-term preventive measure. Fig. 1 shows the flooding level of October 1996. The level of the -540 m drift will probably be reached in June 1997. From that point of time a general rearrangement of the ventilation has to be made because the central return air ventilation via shaft 373 will no longer be possible. This shaft has no connection with the superficia1 system of mine openings. A new return air ventilation system based on shaft 382 as return air shaft will be designed (Fig. 1). The capacity of the future mine fan system will e.g. be determined by the flow conditions in the deformation area mentioned above. For this reason investigations were carried out in a test drift 13a on the level of the Markus-Semmler-Sohle in the stretching zone of the subsidence trough for several days (Fig. 2 and 3). INFLUENCE OF THE OPERATING CONDITIONS OF THE MAIN MINE FAN ON THE RADIATION SITUATION ON SURFACE The beginning of flooding in 1991 was also the beginning of the investigations into the options of future ventilation due to the reduction of the mining area. The first analyses of radon emanation made in May 1991 showed that only about 20 % of the total radon emanation result from systematically ventilated mine workings. This means that despite of existing dams the air streams through the majority of mine openings of the deposit. The analysis of the individual radon inflows illustrates the special problematic nature of the deposit involving all possible effects on the surface. The shutdown of the main mine fan over the long period between 2.10. and 6.10.1991 showed the essential influence of the operating conditions of the fans on the whole radiation situation on surface. Fig. 4 shows the comparison of the radon concentration level and its daughters during a 'normal" weekend with the level during long-term shutdown in the old 'Casino" of the papermill of Niederschlema. This papermill as well as the 'Casino" are situated in the outcropping zone of the deposit section of Niederschlema. The -60 m level was driven as the upper level in this area, from which the panels were driven to about 20 m below the surface. Also below the "Casino" there is such a panel in the vein 'Glirck", whose roof is directly situated below the building in a depth of 39 m. Directly next to it there is the raise 2 of the panel 'Namenlos" in a depth of 27 m. The graphics clearly shows the immediate increase in radon concentration as well as in the daughter concentration after the shutdown of the fans. The elimination of the artificially generated negative pressure results in the reversal of the convection direction due to the natural ventilating pressure. The interface structure allows the mine airto pass through aero- dynamic connections to the surface. Neglecting the meteorological parameters the concentrations of radon and its daughters in- creased by about 350 % as compared to a 'normal" weekend during longterm shutdown (i.e. in 4 days). Furthermore it could be noticed that a stationary state between the radon and its daughters has not been established in the period

Jan 1, 1997

By Gabriel K. Nzulu, Lars Hultman, Per Eklund, Martin Magnuson, Abu Yaya, Prosper M. Nude, Hans Högberg

This study aims to identify individual elements and to gain an understanding of the surface reaction mechanisms, as well as the properties of precipitated pyrite particles observed during the hydrothermal formation of an ore deposit. A combination of X-ray diffraction (XRD), air annealing in a furnace, scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX), and X-ray photoelectron spectroscopy (XPS) was applied to investigate the crystal structure and identify the individual elements, permanence, transformation and chemical/electronic properties of such pyrite.

Jun 1, 2024

By M. Xing, S. Usman, K. Awuah-Offei

"While mines generally focus on achieving operational efficiency, creating shared value for all stakeholders is also a management goal. This includes taking a holistic view of their supply chains and increasing local participation. This paper examines the role of supply chain management in mine management; in particular the effect of a strong local supply chain on regional economic impacts. Using input-output analysis, the impact of a local supply chain on a mining sector’s regional economic impact is examined by increasing local sourcing (increasing local purchase percentage -- LPP) for 10 key commodities. An approach, based on multipliers and excess local capacity is used to identify key commodities. The impacts examined are sales, employment, labor income, and value added. The work is illustrated with stone mining and quarrying in Missouri. Ten percent increases in LPP of the key commodities, in this example, result in $4.1 million additional impact on the Missouri economy. This work can provide insight on how to better create shared value for all stakeholders. INTRODUCTION Little research has been published on improving mine supply chain management (SCM) to enhance regional economic impacts. Although some extensive academic research has explored the importance of an industries’ supply chain, not much is known about how a locally-based supply chain increases shared value in the resource sector. Across industries, traditional SCM is getting more and more complex. This is true of the mining sector as well. However, this increased sophistication is not directed towards increasing shared value for all stakeholders, particularly, the local communities. Further research is required to develop new SCM strategies that enhance local participation. One major point of difference between this work and traditional supply chain management is the inclusion of stakeholders’ shared value as a goal in SCM. Creating shared value has become a business goal in recent years (Porter and Kramer, 2011). The authors use input-output analysis (Leeuw, 2012) to evaluate the regional economic impacts of supply chain decisions, which is not part of traditional SCM. Although input-output analysis has been applied to SCM for decades, most of the research uses input-output analysis as a tool to advance an industries’ own operational efficiency (Accenture, 2014)."

Jan 1, 2015

By RICKARD HANSEN

Vehicle fires in underground mines pose a certain risk for which measures to prevent or mitigate the fires are highly important. Fire protection measures can be divided into active and passive measures, where active measures require an external power to work in the event of a fire, and passive measures could include an existing partition preventing fire spread. As passive fire protection does not rely on activation, it is expected to provide high reliability and a robust solution, and should be considered during the design process. This paper investigates passive fire protection measures that could be implemented in the design of mining vehicles. It was found that passive fire protection should include the use of several measures simultaneously to ensure fire protection throughout the different phases of a fire. Threshold distances for fuel components were calculated, and it was found that combining hydraulic hoses and electrical cables resulted in larger threshold distances. A pool fire along the underside of a vehicle will pose a certain risk, and passive measures should be focused on ignition prevention, making high demands on the insulation/shielding along the underside. Any occurring tire fire may pose a challenge, and the priority should be on preventing ignition. Potential measures include shielding the wheelhouse and applying fire-resistant sealings.