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South Africa?s primary electricity supplier, Eskom, provides incentives to reduce power demand during critical times by granting capital through a Demand Side Management programme. DSM encourages the end user to review and optimize energy consuming systems and use capital, provided by Eskom, to purchase or modify the equipment required to achieve a load-shift. As part of the DSM agreement the mine ultimately acquires the capital equipment and benefits from reduced power costs, but in return is required to sustain the load-shift tactic for up to five years. The paper focuses on one DSM tactic, main fan energy management. In this case, reduced air flows during selected peak and off peak periods, results in a substantial reduction in peak power demand. DSM incentives provided capital for automated main fan control as well as improved control of the mine ventilation systems. To examine the work in detail Gold Fields Ltd Driefontein gold mine near Johannesburg was chosen as a case study.

Jan 1, 2009

By W. Bakiewicz

The Lower Indus Basin deposits form a substantial unconfined alluvial aquifer of excellent quality. This aquifer contains basically highly saline groundwater, overlain in places by considerable amounts of freshwater whose origin can be traced to the present and historical courses of the River Indus. In the past the main source of groundwater recharge has been direct river seepage and water tables were generally deep. Since the establishment of a perennial irrigation regime however, deep percolation from the increased irrigation supplies has predominated and the water-table has risen to within a few feet of the surface. The river system itself is being progressively developed for irrigation and very shortly a situation will arise where the entire low winter flow will be utilised. Fresh groundwater will then be exploited to supplement the surface supplies, and at the same time a drainage system, mainly based on wells will be used to stabilise the water-table at safe depths. This paper discusses some of the methods used to ensure optimum-economic development of the fresh groundwater and describes the general design philosophy evolved by the authors firms for both irrigation and drainage wells, with respect to both well configuation and operation. Water quality standards are discussed in as much as they affect subsequent use of the groundwater. A few particular aspects are considered, including that of the values of the relevant aquifer constants, the construction of wells and the determination of screen losses. A major problem solved during the Lower Indus Project investigations has been the design of wells to-produce fresh water from layers overlying saline water. This solution is also discussed.

Jan 1, 1967

By Allison

During the 1980’s, laboratories opened throughout the United States to serve the analysis needs of a rapidly growing asbestos abatement industry. The samples analyzed were either collected during the abatement of known asbestos-containing materials or were suspect asbestos-containing construction materials. Many asbestos analysts received minimal training and used analytical protocols that were industry specific. False positives (reporting a sample as containing asbestos when none is present) went unnoticed or had minor repercussions. The mindset of the industry was to err on the conservative side – it would be better to identify a non-asbestos fiber as asbestos than visa versa. With growing public awareness of the health hazards of asbestos, other materials began to be tested for asbestos content. Rock and ores began to be tested for naturally occurring asbestos by these laboratories using the same protocols or an in-house protocol. Analysts were given no additional training and accreditation, in most cases, it was not required. With no consistency in sample collection, testing protocol or expertise in analysis, significant discrepancies in final results can be expected. If we further complicate this scenario with misidentification of naturally occurring look-a-likes for asbestos, expensive false positives are likely. To avoid the repercussions of misidentification of naturally occurring chrysotile asbestos from look-a-like fibers in rock and ores, correct sampling and analysis protocols with more stringent scientific diagnostic criteria are needed.

Jan 1, 2005

By Ralph P. Hackl

Ore at the Congress gold property, located near Goldbridge, British Columbia, is extremely refractory with most of the gold disseminated in fine-grained arsenopyrite. Metallurgical testwork conducted by Giant Bay Biotech Inc. indicated that biooxidation pretreatment was capable of increasing cyanide gold recovery from the ore to greater than 90%. To determine if the bioleach process could be successfully scaled up, a 225m' (7950-cu ft) commercial size bioleach reactor was built and tested at the mine site in 1989. At that time, the tank was the largest bioleach reactor ever operated. The objectives of the program were: • to ascertain if the biooxidation rates obtained in lab and pilot-scale reactors could be duplicated in a commercial scale tank; • to identify agitation conditions under which the process will function optimally; and • to demonstrate the bioleach process on a scale sufficient to satisfy the owners and potential investors.

Jan 1, 1990

By K. V. Raj

In the mining industry, computational fluid dynamics (CFD) modeling is used extensively to simulate air flow in underground mines. CFD modeling of pollutant transport in open-pit mines is relatively new. Modeling the actual pit geometry of an open-pit mine and the open domain is complex. The complexity is primarily due to the faceted geometry of an open-pit mine with its numerous associated sharp features. Important issues that are not considered carefully at the geometry level are generally propagated to the subsequent processes. Several challenges and pitfalls are encountered in modeling pollutant transport in open-pit mines. These challenges and pitfalls are related to the geometry, meshing, boundary conditions, and turbulence modeling parameterization. An appropriate mesh selection is critical. A detail discussion of the meshing of the domain of an open-pit mine is presented in this paper. The selection of an appropriate turbulence model, such as kappa-epsilon (?-e), large eddy simulation (LES), Reynolds stress model (RSM), etc., to obtain the best possible solution is equally significant. This paper discusses the various challenges in modeling the pollutant transport process in an open pit and some of the approaches adopted to address these challenges.

Feb 27, 2013

By M. Ge

Signal processing is a major challenge for In-Seam Seismic (ISS) technique. Fourier Transform is an important tool for signal processing such as frequency analysis. However, for ISS signal, localized information, especially time-frequency localization is even more important. Wavelet Transform (WT) provides another approach to study the signal as a function of frequency and time. The objective of this paper is to demonstrate the application and advantages of WT to seismic signal analysis. Both transmission and reflection signals from coal mine void detection experiments are analyzed. The results illustrate that WT appears to be a powerful and convenient method for the in-seam seismic signal processing.

Jan 1, 2007

By Gui DeReamer

Located on the Wabash River in the central portion of the state, the city of Lafayette, IN is relatively small compared to most cit-ies that incorporate tunnels into their combined sewer overflow (CSO) systems. The original CSO plan for the city was to replace two aging lift stations that were built in the 1950s. The original con-cept was to build a new sewer using conventional cut-and-cover construction to eliminate one of the lift stations ? the Parking Lot Lift Station ? and build a new regionalized one at the location of the Pearl River Lift Station. The initial sewer design was sized just to handle the flow that would eliminate the Parking Lot Lift Station. The planning for this project was being developed as part of the city?s CSO long-term control plan (LTCP) that focused on reducing the overflows from the city?s 14 overflow points. However, during the development of the CSO LTCP, a major industrial user indicated it would be increasing its flows to the system, which required additional conveyance capacity to meet the city?s CSO LTCP. After reviewing the design concepts with city representatives during the planning phase of the project, the mayor indicated that he wanted to minimize impacts to downtown businesses; therefore, trenchless alternatives were considered. The last piece of the puzzle that drove the project away from a small diameter pipeline was discovered during a flow monitoring program to collect flow data for the CSO LTCP project. This study revealed a major restriction in the 100-year-old Pearl River Trunk Sewer, located beneath four active railroad tracks. To eliminate this flow restriction, provide more overflow storage and reduce the impact to local businesses, a new 2.7- to 3.6-m- (9- to 12-ft-) diameter tunnel sewer became the most viable solution.

Jan 1, 2011

By Fritz Grübl

Modern shield TBMs allow tunnel drives through almost any type of ground. Thanks to high elaborated technical measures, significant subsidence of the ground surface can be almost entirely avoided. The tunnel lining behind the TBM must be capable of withstanding all loads without deforming, especially during ring erection and advance. Single-shell tunnel linings behind the TBM, usually reinforced concrete segmental rings, can be designed to fulfill this demand. With many projects, however, damage occurs to the lining. Repair costs may be extremely high. Reasons for damages and possibilities to avoid them are shown and explained.

Jan 1, 2001

By W. Lin, M. J. McPherson

When a large area of open gob collapses suddenly, a windblast is produced that can cause considerable damage throughout the infrastructure of a mine. In a few cases, the windblast has been accompanied by ignitions of methane and/or coal dust. This paper describes the conduct and results of laboratory tests involving the compression of mixtures of air, methane and coal dust under a falling weight and while allowing controlled escape of the mixture. The transient responses on pressure and temperature sensors were recorded. In addition to an analysis of those records, the paper highlights those conditions in which ignitions occurred.

Feb 24, 1997

By J. Starwood

Post-super-cycle mining executives must exploit every aspect of the value chain to deliver continued value to stakeholders. Integrating enterprise-wide information technology with value-chain-wide operational technology, known as IT-OT integration, is essential to extracting optimal results from the value chain. Mining companies trail other industries with respect to IT-OT integration across the value chain. Manual data consolidation and value chain optimization using spreadsheets and human intelligence are widespread practices within the industry. Increasing automation with smart devices and controllers means the volume and velocity of data will soon increase beyond human abilities. Enterprise Architecture provides a method for aligning information technology with the business operating model to successfully implement IT-OT integration. A Value Realization Framework (VRF) provides a means for predictable traceable value realization from IT investments and assets. With these principles, frameworks, models, methods, and techniques, mining organizations can accomplish IT-OT integration that provides their executives with a strategic value-chain-aligned platform for sustained value realization over the long term.

Feb 23, 2014

By T. McCallum

Crud is a common concern in SX processes and is formed as a complex solid stabilized emulsion of aqueous and organic.1,3 Crud formation is highly dependent on the amount of solids entering the circuit and is influenced by a number of other operational factors. A common practice for crud processing is interfacial pumping, wherein crud, organic, and aqueous are pumped from the settlers for treatment and utilizes a variety of equipment. These mechanical means of crud processing are effective, however, require significant processing time and require oversight to prevent the return of contaminated organic. Cytec has developed a unique crud treatment process utilizing both chemical and mechanical means to enhance the solid/liquid separation. The use of ACORGA CB? 1000 crud busting reagent allows a rapid separation of solids from the organic phase and provides similar volume recovery to current practices. The process allows operations to return clean organic back to the plant more efficiently and may enable operations to process more crud. In addition, the organic quality of the recovered organic is higher than that recovered by typical means, which can lead to operational cost savings.

Feb 27, 2013

By A. H. Shapiro

A decanter centrifuge of novel design was developed for the dewatering of fine-solids slurries having micron-range particles that form paste-like, flowable, hard-to-dewater cakes. The design combines a compound beach with a cake-flow control structure that allows expressed liquid from the cake in the dry beach region to be returned back to the liquid pool while maintaining high solids throughput. In order to provide optimal performance with various operating parameters (feed rate, centrifugal gravity, pool, differential speed, concentration of feed solids, and different slurry types), the cake-flow control is adjustable. The second part of the beach is preferably at zero angle. Tests showed that the new design allows increases in both solids dryness and solids throughput.

Jan 1, 2001

By Mirjana Boskovic

LKAB’s Kiirunavaara Mine is a sublevel caving iron-ore mine located above the polar circle in northern Sweden. The mine has been proclaimed seismically active since 2008 after a magnitude 3 seismic event, according to Swedish National Seismic Network (SNSN). At that time the Kiruna Mine did not have mine-wide seismic system. Since then, the Kiruna Mine experienced several damaging seismic events of which the largest one on the May 18, 2020. The magnitude, based on the moment tensor inversion results on data from the SNSN as well as seismic stations in Finland and Norway, is estimated to 4.2 ± 0.2 moment magnitude. The seismic event on the May 18, 2020 was located in the middle of the one of the productions areas and caused the major damage in the mine, damaging several kilometres of drifts on six mining levels, some of them beyond the practical repair. These damages affected four of ten production areas on several levels, some more some less. Luckily, no person got injured from the seismic event and the very long aftershock series. An important part in the whole process after the seismic event was information flow and decision-making process. It was very important to keep workers and community informed as that contributed transparency of decision-making and decreased the speculations. Resuming the production in the damaged areas in the safe manner, very soon become main focus for the mine management. It was obvious that not only rehabilitation of the areas is needed to resume the production. It was A MUST to understand the factors behind the seismic event and its mechanism to be able to avoid same situation and prevent seismic event of similar size. Mine engineers had to think outside the box to find the solutions to ‘rescue’ every drift that they could to be able to make good enough base for continued mining of the area. The paper describes actions taken in a very complex process of recovering the area that we from the beginning thought need to be abandon. Seismological analyses of the event on May 18, 2020 and past activity in the area, damage mapping, detailed studies of structures and geology, numerical modelling as well as engineering judgement were used as base for all our decisions how to proceed in attempt to restore mining of the area heavily damaged by 4.2 moment magnitude seismic event, in a safe way.

Apr 26, 2022

By Greg Sheppard, Eduardo Nebot

Australian researchers have developed new technologies aimed at improving safety and productivity at openpit mines. A data acquisition and feedback system for electric rope shovels has been shown to substantially reduce cycle times and decrease excessive machine duty caused by stalls. This data acquisition system was developed by the Cooperative Research Center for Mining Technology and Equipment (CMTE). It has been tested on a P&H 4100A shovel at Coal & Allied’s Hunter Valley operations and a P&H 4100XPB at BHP Billiton Mitsubishi Alliance’s Goonyella Riverside Mine in Central Queensland. In addition, CMTE member P&H Mine Pro Services has used the technology to acquire field data from a P&H 4100XPBrope shovel at RAG’s Belle Ayr Mine in Wyoming’s Powder River Basin.

Jan 1, 2002

By A. J. Hendron, J. E. Monsees

INTRODUCTION This paper is the outgrowth of work done by the authors to prepare the seismic design criteria for underground structures on the Southern California Rapid Transit District (SCRTD) Metro Rail Project. It is a follow-on to a similar paper presented at the October, 1984, ASCE National Convention (17). For design, the earthquake-induced distortions recommended herein are to be added to the normal static loading conditions for the underground structure. This design approach has been used by 18 section designers on the SCRTD Project. Preliminary results from two- and three-dimensional finite element solutions have partially verified the approach. Areas where additional research is needed for special cases are identified. EFFECTS OF EARTHQUAKE The effects of earthquakes on underground structures may be broadly grouped into two general classes -shaking and faulting. In response to earthquake motion of bedrock (shaking) , the soil transmits energy by waves. Seismologists identify various types of earthquake waves, but underground engineers are generally interested in the effects of transverse shear waves which produce a displacement of the ground transverse to the axis of wave propagation. The orientation of propagation is generally random with respect to any specific structure. Waves

Jan 1, 1985

The two candidates in the upcoming presidential election in the United States each say that they have their own solution to the nation?s energy problems - solutions that will increase the amount of energy available, lessen the nation?s dependence on foreign sources and reduce the amount of pollution released to the atmosphere. Democratic nominee Sen. Barack Obama and Republican candidate Sen. John McCain both advocate research funding for coal-to-liquids and clean coal technologies. McCain also supports increased oil and gas drilling offshore. And Obama has even made some noises in that direction, although his plan leans heavily on the increased use of renewable energy sources. The energy debate is not new to this election. Congress and whichever party is in the White House has for years been trying to craft a comprehensive energy policy. One difference in this latest debate is that the increased use of nuclear energy has gained more attention. Current President George W. Bush has said he favors the increased use of nuclear power as part of the nation?s energy package. And McCain said he supports the building of more nuclear power plants. Obama has not said much about that. The American public is also showing signs of changing its stance on nuclear energy. To be sure, images of Three Mile Island and Chernobyl are still alive in some minds. However, the American public has said it wants cheaper energy and they want it produced more cleanly. With nuclear, the nation can have both. In the United States, nuclear accounts for slightly less than 20 percent of the electrical power used (see interview with Gary Steele of Energy Fuels on page 27). Globally, that figure is about 15 percent. And there are several nations that derive better than half of their power from nuclear sources. Add to that the world?s increasing need for more energy and the future of nuclear is bright.

Jan 1, 2008

By B. DANIEL MARJAVAARA, I. A. SOFIA LARSSON, ANNA-LENA LJUNG

The flow field and coal combustion process in a pilot-scale iron ore pelletizing kiln is simulated using a computational fluid dynamics (CFD) model. The objective of the work is to investigate how the thermal effects from the flame affect the flow field. As expected, the combustion process with the resulting temperature rise and volume expansion leads to an increase of the velocity in the kiln. Apart from that, the overall flow field looks similar regardless of whether combustion is present or not. The flow field though affects the combustion process by controlling the mixing rates of fuel and air, governing the flame propagation. This shows the importance of correctly predicting the flow field in this type of kiln, with a large amount of process gas circulating, in order to optimize the combustion process. The results also justify the use of down-scaled, geometrically similar, water models to investigate kiln aerodynamics in general and mixing properties in particular. Even if the heat release from the flame is neglected, valuable conclusions regarding the flow field can still be drawn.

Apr 20, 2021

By James J. Brady, Joginder S. Bhore, Robert B. Gordon, Jimmy W. Honeycutt

The authors of this paper have a combined construction experience of 70 years. They have served as engineers and managers on projects throughout the United States and Canada. Approximately 50 shafts have been sunk under their direct and daily participation. Several shafts have been selected from each of their experiences and have been briefly summarized here. SHALLOW SHAFT SINKING Sinking shallow shafts in highly urbanized areas adds an additional set of problems to those encountered in normal sinking operations. During the time between July, 1975 and early 1981, a series of shafts were sunk for The Washington Metropolitan Transit Authority. All of these were located along the "A" line, starting soon after the route departed from its path along Connecticut Avenue, proceeding to Wisconsin Avenue and then along Wisconsin Avenue to the city line at Western Avenue. (See WMATA System Map, Figure 1) The first three shafts were subcontracted from Morrison-Knudsen & Associates, Contract A9a, in July, 1975. They were: Albemarle Street - 27'6" diameter, 78'O" deep Brandywine Street - 30'6" diameter, 88.6' deep Ellicott Street - 33'0" diameter, 110'0" deep

Jan 1, 1985

By Anthony S. Spearing

The vast majority of the estimated 100 million rock anchors installed in mines in the USA per year use resin cartridges (Tadolini and Mazzoni, 2006). About 4.5 million per annum of these are bolts with a mechanical shell that if properly installed become effective active supports on installation. In addition, cable anchors (mostly passive) are installed with typically 4 ft of effective resin anchorage length sometimes with mechanical shells, which further makes the installation more difficult. This is because the cable (even with a stiffener tube) is not very rigid. When installing bolts with mechanical shells and cable bolts in the holes, the back-pressure can be so high that the installation is unsuccessful often creating a ?spinner? (an un-tensioned bolt) at best or buckling the bolt thus requiring another bolt/cable to be installed, or leaving a poorly functioning unit. The installation problems can create a significant potential safety hazard and waste time and money. Using a purpose designed test rig that physically inserts different rock anchors into pipes with resin and measure the back-pressure developed with time during the insertion/ installation. The test installation procedure is designed to mirror that used underground by rockbolt operators in coal mines. In addition a computer model has been calibrated that can predict the approximate back pressure of new anchor and resin combinations acting as a screen before physical testing. This research has lead to an understanding and quantification of the insertion back-pressures and this already resulted in improved prototype designs that could lead to more reliable mechanical shell and resin bolt installations.

Jan 1, 2009

Bortech’s BoreClad corrosion protection system will be displayed at MINExpo. BoreClad is an innovative system for inside diameter cladding of nozzles, tubes and other circumferential devices. Pressure vessels, mud pumps and other mining equipment must be protected from corrosive caustic chemicals. Usually manufactured from mild steel, they can be clad with a protective material, such as stainless steel, to provide corrosion resistance. However, most welding processes leave voids where corrosion can damage the base metal. BoreClad provides void-free welds by combining gas metal arc welding with automated feed and rotation of chuckable parts. Workpieces of up to 915-mm- (36-in.-) long with a 460-mm- (18-in.-)swing can be clad with stainless steel, Iconel or other exotic metals. In addition to eliminating the voids associated with hand welds, BoreCladcan lay more than 2.2 kg/h (5 lbs/hour) of metal. That is a significant reduction in weld time. Web sitewww.bortech.com.

Jan 1, 2004