Search Documents

By M Bourke

Modern computers and software provide powerful tools for the geologist to construct reliable models of geological resources, and the mining engineer to produce accurate and workable mine plans. Over the years many people have developed a phobia of computers, especially for geological analysis, modelling and mine planning. This phobia is often caused by a lack of knowledge, poor training or a bad experience. The adoption however of computers for geological modelling and mine planning is now becoming mainstream. With the correct training, a good understanding of input data, and detailed knowledge of the required results, the phobia can safely be overcome to provide mining operations with increased productivity.

Jan 1, 1999

By M Hawkes, Z Ji Gang, Z Ming, R Hassell

As underground mines become more geotechnically challenging with increasing depth and excavation size, the requirement for ground support to be installed as per design becomes more critical. The verification of installation quality for cable bolts and grouted rock bolts is difficult to assess. Current methods to control quality have limitations; pull testing is largely inconclusive with only extremely poor installation being identifiable. Audits during installation can only capture a small percentage of installed bolts. Following large rock mass displacement from either squeezing ground or seismic events, even previously well installed bolts may have yielded and require replacement. A method to provide an improved understanding of the reinforcement installation quality is Non- Destructive Testing (NDT) using acoustic reflection. To validate the accuracy of an NDT system, both plain and bulbed strand cable bolts were grouted in clear plastic tubes. The encapsulation grout quality was deliberately varied from full encapsulation through to partial encapsulation and a range of different size voids. The clear tubes allowed the ground encapsulation to be observed. Cable bolts strands were cut at varying lengths and different water cement grout ratios were used. Acoustic testing of the cable bolt specimens was completed blind; the technicians were not aware of what was being tested. The NDT results correlated well with the grout encapsulation, with differences between full encapsulation, minor voids and major voids being determined. The different water cement ratio and bolt lengths (including when partially cut) were also identifiable but with some discrepancies. Trials of the technology underground have also shown the data collection process to be relatively quick with each bolt taking 1-2 minutes to test, with interpretation of the results able to be completed soon after. The NDT results collected from the underground trial showed a wide variance in cable bolt grout encapsulation quality indicating that there were installation issues.

Mar 15, 2021

By P. P. Andrieux

The recovery of the Zone G crown pillar, located between the bottom of the open pit and the top of the underground workings at the Raglan Katinniq Mine in Nunavik, started in the summer of 2008 and should be completed by the end of 2009. This article describes the rock mechanics-based approach implemented to design the recovery of this valuable block of ore. The stereophotography-based ShapeMetriX3D technique was first used to provide a comprehensive assessment of the various joint sets that comprised the pillar. Then, the statistical distributions obtained for the dip, dip direction, spacing and persistence of these sets were used in conjunction with the geometry of the large-scale faults present in the area to build and run a series of explicit rigid numerical models. Each of these models had a slightly different jointing geometry, randomly constructed from these statistical distributions. Incorporating in a properly formulated numerical model the variability of some of the input parameters has allowed the engineering team to assess in a rational and reliable manner the likelihood of success of the proposed mining method and sequence.

May 1, 2009

This presentation addresses the sources and weighting of project risk in coarse gold deposits with relevance to experiences at the Ballarat mine and Castlemaine goldfield. With sample representation and reliability often a source of great error in the resource estimation of coarse gold deposits, it follows that this matter should be of greatest risk to a mining project - but is it? What are the costs and efforts required to best quantify the sampling error due to nuggetty effect? After all, the main problem in Victorian gold mining ventures in the current decade is not the amount of gold available, but defi ning which portion of it can be converted to Ore Reserves or more so profitable gold bars. The author postulates that greater risk to the project lies in the geological interpretation and matching resource spatial parameters to mining methods, than the degree of uncertainty related to grade due to nuggetty gold. Recent experience in the Victorian goldfi elds is that the investor market has already severely discounted Mineral Resources reported in accordance with The JORC Code - so if they don't believe in the capacity to upgrade the resource why should we? To this end, Castlemaine Goldfi elds Ltd at its Ballarat gold project does not intend to estimate its gold mineralisation for public release, instead choosing to focus on the geological interpretation and mine planning elements. So with coarse gold deposits, is your Mineral Resource reported with The JORC Code a glass half full or half empty? Our mining forefathers in Victoria had no predictive tools which could define resources to any degree and yet were successful. By over emphasis on the definition of mineral resources and particularly the sampling error, are we ignoring the basics of cost control, solid geological interpretations and maximum mining flexibility. This is an ABSTRACT ONLY. No paper was prepared for this presentation.

Aug 1, 2010

By John J. Mulligan

Since 1941 the Federal Bureau of Mines has been conducting an intermit-tent program of placer and lode investigations to evaluate the potential tin resources of the western Seward Peninsula tin belt. Previous investigations were made in the Potato, Cape, Brooks (Lost River), and Ear Mountain areas. As part of this program the Bureau made a reconnaissance of reportedly tin-bearing stream gravels in areas adjacent to the previously worked tin deposits at Lost River and Potato Mountain. The objective of the reconnaissance was to determine if additional areas might be favorable for lode or placer exploration. The work was begun late in the fall of 1956 and completed during the following summer. The streams sampled were the Lost River and York Creek in the Brooks Mountain area and the Anikovik River and Kigezruk and Baituk Creeks in the York area. Samples were obtained by churn-drilling methods employing conventional placer-evaluation procedures. Holes were drilled at wide intervals at sites chosen as being representative of drainage areas rather than of individual gravel deposits. Minor to trace amounts of tin were found in the gravels of all these streams, but the highest grade was 0.35 pound of tin per cubic yard in the gravels of Lost River below the mouth of Tin Creek. Small amounts of gold were found on Baituk Creek and in one hole on the Anikovik River; the highest grade did not exceed 10 cents per cubic yard. Traces of scheelite and barite were found on York Creek, chromite was encountered in one hole on the Anikovik River, and minor amounts of titanium minerals (probably derived from basaltic intrusives) were found in the York area.

Jan 1, 1959

By Yuhua Pan

Generic mathematical models have been developed for simulating heat transfer in two types of slag resistance heating electric furnaces for sulphide smelting: i) six-electrode-in-line rectangular furnaces and ii) three-electrode circular furnaces. The models are based on three-dimensional steady-state heat transfer of conduction, convection and radiation. Solidification of liquid slag into solid slag by water-cooling units, for use as freeze lining of furnace walls, is also considered in the models. The developed models are capable of providing predictions with reasonable accuracy for electric furnaces on 1) temperatures in slag, matte, cooling water, freeze lining and other solid regions as well as temperatures at various fluid/solid interfaces, 2) freeze lining thickness, 3) furnace smelting rate and 4) furnace heat loss rate. These computer models are built into executable application programs that are very efficient, with execution time less than one second, and can be easily portable to most computing platforms. This paper describes, as an example, the modelling results on heat transfer in six-electrode furnaces. The major modelling results show that in six-electrode furnaces uniform electric power inputs to the electrodes likely lead to low temperature regions close to slag and matte tapping ends of the furnaces, and the power input and the formation of air gaps between freeze lining and cooling units have significant influences on the thickness of freeze lining maintained by the cooling units.

Jan 1, 2006

By William Ferguson, Claude Deveau, Wade Hazel, Stephen R. Young, Allen Lussier, Robert Copeland

"LocationSometimes known as the Bernie Lake mine, the mine is located about 180 km east-northeast of Winnipeg on the northwestern shore of Bernie Lake, close to the Nopiming Provincial Park and the Manitoba-Ontario boundary. The mine is accessed from Lac du Bonnet which is linked to the provincial road system.Brief Description of OperationTantalum Mining Corporation of Canada Ltd. operates an underground mine employing ramp access, room and pillar mining, and shaft hoisting for the production of tantalum, lithium and cesium minerals. Daily campaigned crushing of the tantalum and lithium ores supply separate concentration circuits. Tantalum recovery employs conventional gravity equipment together with recently developed centrifugal concentration methods. All tantalum concentrates go to Cabot Performance Materials for the production of tantalum chemicals and metal. Lithium minerals are recovered using heavy medium separation and silicate flotation to produce spodumene and montebrasite/amblygonite concentrates. The lithium concentrates are shipped worldwide for use in ceramics, specialty glass and mold powders. Cesium processing involves the dry grinding of pollucite as feed stock for the recently built on-site chemical plant dedicated to tl1e production of cesium formate, a high-density drilling fluid for use in the oil industry."

Jan 1, 2000

By Mary Cocklan-Vendl

Regulatory processes associated with development of a world class lead-zinc mine, Red Dog Mine, in northwestern Alaska were reviewed and evaluated. Informal interviews with key project personnel, consultants, and agency field and permitting specialists provided perspective on the regulatory successes and failures of the project. Due to potential impacts to air quality, water quality, wetlands, and National Park lands, an Environmental Impact Statement was required. By developing a comprehensive baseline of information on the existing environment to aid in minimizing impacts during project siting/design and through regular coordination of evolving project plans with regulatory agencies, the mine developers were able to acquire necessary permits in a timely and cost effective manner. The only major exceptions occurred when inadequate information was collected on dispersal of airborne particulates, rates of surface water run-off, and groundwater quality. These deficiencies resulted in the need for design changes, unscheduled construction, additional environmental monitoring costs, and delays in issuance of the NPDES permit.

Jan 1, 1992

By Thomas R. Larson

"Many concentrators use re-circulating “plant” water for dilution in their flotation circuits. However, if crusher dust suppressants, ball mill grinding aids, or even agitator bearing grease are introduced into this water, and the water itself is not subject to cleaning steps, then sufficient quantities of these chemicals may appear in the flotation cells and begin to impact the flotation separation. A bench flotation procedure has been coupled with statistical analysis in order to estimate the impact of small quantities of non-flotation chemicals on flotation performance.INTRODUCTIONCleveland Cliffs produces iron oxide pellets for blast furnace feed, and is developing the capability to produce ferrous metallic products to supply a wider customer base. Cliffs manages five North American iron mines, including the Wabush mine sites in Labrador and Quebec. Based on various characteristics of the ore bodies, the flow sheets of the five mines are diverse. For example, Hibbing Taconite uses magnetic separation alone as their primary upgrading method, but Northshore and Empire use magnetic separation followed by flotation, and Tilden uses flotation alone. Last but not least, the Wabush concentrator upgrades primarily with gravity and electrostatic separation techniques.At Northshore, concentrate from the magnetic separator circuit is fed to a reverse flotation circuit. By design, the magnetic separators operate at the highest possible recovery of magnetite, as the separator tails are discarded, and relatively high silica content was acceptable to Northshore’s customers. As the steel-making industry moved toward lower and lower slag volumes, the silica content in the magnetic separator concentrate became a problem. The flotation step was added in the late 1980s in order to decrease the silica assay of the magnetic separator concentrate to meet the current customer requirements. In this setting, the flotation feed stream contains very little silica that occurs as liberated quartz particles. As the degree of liberation of the flotation feed stream is then a limiting factor for silica removal, the online grind control then was linked to flotation in the overall plant control system so that grind can be adjusted to achieve improved liberation if necessary for the flotation process."

Jan 1, 2002

By Scott G. Giltner, Alex Schwenk

Blasting within 250 ft of a crusher was successfully executed through the application of electronic detonators, 3-D imagery, signature hole analysis, custom loading of blast holes. The blast was well contained, the vibrations were minimal, and there was no flyrock.

Feb 1, 2020

By Emma Arakelova

An increase in concentration of a Zn-containing volatile complex for synthesis of ZnO films was investigated when processing their target by ultraviolet radiation emitted by mercury lamp. The experiments were carried out using a flow-type quartz reactor. ZnO tableted target was preliminarily irradiated during 2 to 7 hours. H2O2 (98%) vapor at 25Pa passed through the reactor with ZnO target at 373K. As substrate material, five subsequent quartz cylinders were used at 423K. The experiment lasts 4 hours. H2O2 decomposition on ZnO surface was accompanied by formation of a Zn-containing volatile complex which passed in gas phase and decomposed on the substrates with isolation of final ZnO. The concentration of the Zn-containing volatile complex (N) in gas phase increases with UV pre-irradiation time (t) (without irradiation N = 1.05 1011 particles/cm3; after t=2 hours, N = 5.19 1011 particles/cm3, after t=4 hours, N = 9.95 1011 particles/cm3; after t=7 hours, N = 1.86 1012 particles/cm3.

Jan 1, 2006

By B Green

With a focus on safe productive tonnes, there has been an ongoing drive to increase the productivity of the mining fleet across BHP Billiton. In response, a team from the Iron Ore business was formed to review all aspects of the end-to-end drill and blast process and to challenge conventional practices that limit production efficiency. As a result of the outcomes of this work, a number of initiatives were identified to improve operational practices that have also delivered significant cost savings.One such initiative was to increase pattern size to a minimum of 1 Mt where practicable, thereby creating ‘megablast’ as a new standard across all mines. To achieve blasts of this size, the team had to overcome the complex problem of integrating wall control into the megablasts.With traditional blasting techniques, the key strategy, which is also historically inefficient but was thought to be integral to having stable, safe walls, was to utilise the trim blasting/modified production blasts technique (ie narrow blasts along the pit wall designed to ‘peel off’ the material while minimising the effects of vibration and charge confinement on wall integrity).Small traditional trim patterns comprise three to four rows of production holes and one or two rows of batter/buffer holes of reduced diameter that require the firing face to be completely exposed before blasting. This is an extremely slow process that requires a lot of resources for very little tonnage while adding additional expense to the final cost per tonne.This paper will show how the megablast approach was developed to control damaging vibration and confinement effects, flyrock and fragmentation while having the largest possible blast that includes wall control. The new practice is based on a theory that involves the initiation point and control row being the second row of holes from the pit wall itself. Adjusted charges in vented batter and buffer holes help to achieve an optimal toe design, and at the same time create a zone of broken ground that absorbs damaging vibrations formed by the attached production blast of any size, whether it is a straight wall or a multi-angled complex pit shell design.Using the new style of blasting has allowed an increase in the size of the patterns from an average of 300 kt to over 1 Mt whilst maintaining pit wall integrity. Case studies will be presented showing drill, charge and tie-in designs with the presentation having additional blast videos, including overall shots of blasts and in-close footage of what happens behind the blast at the crest of the planned catchment berm.The paper will also demonstrate the flow-on effect of using this style of blasting to reduce operational costs associated with other downstream processes, such as the reduced requirements for pattern preparation, an increase in productive digging, reduced maintenance costs and a decrease in fuel burn for equipment.CITATION:Green, B, 2015. Megablasts – enabling technologies in BHP Billiton Iron Ore, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 599–606 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By R. A., Pallanch

SO many variations of lead-zinc ores occur in nature that it is impossible to state any rules that will apply to the concentration of ores of this type. Some have lead and zinc in approximately equal amounts; others may have pre- dominant amounts of one or the other metal. There are gradations from all sulfide to completely oxidized minerals. Some such ores carry little pyrite, others contain much more pyrite than they do lead and zinc combined. The behavior of ores in flotation is largely a function of their lead-zinc ratios. their content of pyrite or pyrhotite, the nature of existing soluble salt conditions, the character of the gangue constituents: and the speed with which the minerals float. For the purposes of this paper only those lead-zinc ores handled commonly in present-day flotation practice will be considered. These are practically all-sulfide ores with relatively minor degrees of sulphatization or oxidation.

Jan 1, 1936

By J. Dupre, A. Gontcharov, H. Pepin

Produced by the conventional TIG welding CMSX-4 welds had been studied. It was demostrated that microstructure of welds depended on filler materials, welding parameters and joint design. Epitaxial solidification of CMSX-4 clad deposits produced a directionally solidified structure while welding with the similar filler material. Defects free clad welds were obtained by TIG welding without preheating using similar and dissimilar filler materials.

Jan 1, 2006

By W. Beres, M. Bielawski

Recent research on the development of erosion resistant coatings has been directed to the finite element modelling of the behavior of coating and substrate, and their interface under the impact of eroding particles. The approach presented in this paper is based on advanced computer simulation techniques using ABAQUS/Explicit to investigate stress and strain at the surface and at the coating/substrate interface of multilayer coatings under single particle impact. It was found previously that solid particle erosion mechanisms are predominantly governed by the kinetic energy of the impacting particles. However, recent modelling efforts revealed that effects of various material models could be also significant. Therefore, different material models representing relevant coating and substrate properties were investigated and the effects of these models on the coating/substrate response were studied. Particularly, differences between elastic, elastic-plastic and brittle cracking model responses were assessed.

Jan 1, 2006

By Charles S. Allbright

This report describes hydrogenation of petroleum distillate fuels in bench scale equipment and the effects of hydrogenation on the storage stability and the composition of the fuels. Two distillate fuels were hydrogenated in laboratory equipment using a commercially available cobalt molybdate catalyst. Reactor temperatures were varied from 600° to 850° F and pressures from 100 to 600 psig. Product fuels were analyzed by ASTM, Bureau of Mines, mass, and infrared methods. Hydrogenation of a catalytically cracked fuel from Oklahoma crude oil significantly improved the storage stability, reducing insoluble gum formed during 9 months of storage at 110° F from 19.0 to 1.3 mg per 100 ml fuel, average. Conversion of the olefins to other hydrocarbon types varied with the temperature of hydrogenation--at 700° to 850° F the conversion was mainly to aromatics, at 650° F about 50:50 to saturates and aromatics, at 600° F principally to saturates. Processing a fuel composed of a mixture of virgin distillate and catalytically cracked stock, both from Illinois crude, at 700° F and 200 psig effected marked improvement in stability; the buildup of insoluble gum in storage was lowered from 18.3 to less than 1 mg per 100 ml fuel.

Jan 1, 1967

By Brain E. Ladd

A load test program was performed on two auger cast piles constructed in the Inner Coastal Plain geology of North Carolina. Both test piles were installed through Coastal Plain deposits and into underlying Piedmont residual soils; one test pile was embedded into partially weathered rock (PWR). The recommended 100-ton design load was confirmed by a test program that included instrumenting the piles with strain gages. The two piles performed differently during the load tests due to the effect of embedment into PWR. Loading Test Pile No. 1, which was not embedded into PWR, to failure at about 230% of the design compressive load allowed for evaluation of the mobilization of the ultimate shaft and end bearing resistances. Mobilization pile resistance was evaluated by comparing shaft and end bearing resistances to top of pile deflection (?) normalized by the pile diameter (D). For Test Pile No. 1, the ultimate average shaft resistance was achieved at ?/D of about 7.5% and ultimate end bearing resistance at ?/D of about 9.5%. Test Pile No. 2, embedded into PWR, achieved a ?/D of only about 4% at 200% of the design load and was not loaded to failure. Shaft resistance was mobilized at a different rate within each individual geologic layer, i.e. ultimate shaft resistance did not occur simultaneously for all geologic layers. As the available total shaft resistance was exceeded and end bearing mobilized, the unit shaft resistances reduced from the peak values. A modified Davisson offset using ?/D of about 6.5% appears applicable for evaluating the ultimate capacity of auger cast piles in the Inner Coastal Plain.

By Nasri Munfah, Raymond E. Sandiford

"Superstorm Sandy (Sandy) created a storm surge that inundating many of the tunnels that pass beneath the Hudson and East Rivers. The tunnels are vital infrastructure links for the economy of New York City and the northeast region. The sea water, which contains highly reactive salts, caused significant damage to electrical and mechanical systems. In addition, the salt water inundation left corrosive precipitants on the tunnel linings and on and within electrical duck banks. After the salt water was evacuated from the tunnels, condition assessments were performed using a state of the art approach involving high resolution laser scanning, digital imaging, and thermal imaging. These scans were performed prior to hands on inspections. The damage assessment concluded that, although the tunnel structural linings were not damaged, the interior elements of the tunnels needed major rehabilitation to arrest the continual deterioration of the structures. This paper details the state of the art approach used for these tunnel inspections. INTRODUCTION On October 29, 2012 Super Storm Sandy flooded a large number of both transit and vehicular tunnels in the New York Metropolitan area. The region’s transportation network was severely disrupted. The storm damage is estimated to have been in excess of $30 billion, and with the tunnels out of service, the local economy was losing hundreds of millions in economic activity. Restoration of these tunnels was a very high priority and the resulting expedited restoration process did not always provide adequate time for comprehensive condition surveys. This resulted in many of these surveys being conducted after service restoration. Inspecting highly trafficked transit tunnels is challenging and the logistics of working in short night outages led to a rethinking of the conventional inspection approach. Traditionally, visual and tactile methods are first used to inspect tunnels and then quite often followed by LiDAR (Light Detection and Ranging) scanning and perhaps infra-red scanning. For multi-mile tunnels, the time required to visually map tunnel features can be quite extensive. By performing the scanning first and then performing the visual and tactile inspections, one is able to use the scan data to identify the specific areas that need detailed inspections. This approach was used quite successfully for a number of the NYC tunnels."

Jan 1, 2016

Risk management has taken on renewed vigor since the economic crisis of the late 2000s. The resources of governments, individuals, and corporations are being stretched to a point where only the most promising projects move forward. Risk management is a crucial part of the decision making process, yet it remains a broad term that includes disciplines from engineering to finance. A collaborative effort will be necessary to ensure that the most auspicious and appropriate projects are the ones moving forward. Risk management can be quantified to an extent by comparing the likelihood of an instance with the result of consequence of the instance occurring. In this manner it is possible to assign risk factors to instances and ultimately, begin to associate monetary value to the instance. Carbon sequestration is an emerging field that has a number of unique challenges. Risk management and mitigation must be an integral part of the overall picture. This begins with the planning and design phase, continues through implementation and production, site closure, and does not cease until termination of liability. The ability of carbon sequestration projects to successfully assess, mitigate, and recover from leaks will be a decisive characteristic of overall success. The costs of mitigation and failure will need to be analyzed on a test level, but will still need to be reliable enough to extrapolate to a commercial level operation. This paper will build a risk management profile based on case studies and field tests in Tennessee and Virginia. These tests are scheduled to commence in late 2013 and consist of small-scale injection tests in unconventional storage reservoirs with an emphasis on enhanced coalbed methane (ECBM) recovery and enhanced gas recovery. The ultimate goal will be to provide a clear and concise direction to move carbon sequestration from the test phase to commercial scale. While it is necessary from a risk management perspective to analyze all risk points, the scope of this paper will focus on pre-injection risk assessment for carbon dioxide (CO2) leakage potential. Despite the differences between the two tests, CBM compared to shale among other differences, a framework for analysis and mitigation can be developed pertaining to leakage risk. The probability of each type of failure will be assessed and analyzed, and plans to mitigate or reduce these risks will be reviewed.

Aug 1, 2013

By William H. Hamilton

Tunnel-driving capabilities in terms of feet per hour have advanced several hundred percent in the last century. Indications are that this capacity will double each decade for the next three decades. These future improvements will be made possible by a greatly increased need for underground excavation and the awareness of industry of its own latent capabilities. The factors of most interest to any potential user of a tunneling machine are those making possible an increase in production. The first and most obvious factor, and probably the one that has created the excitement and interest of most people, is the increase in boring rate through faster rock fracture and improved support systems. Boring rate can be increased by more horsepower in the form of increased thrust, torque, and cutterhead speed, and by better cutters and cutting methods, better material-handling systems, and better ground-control systems. All of these items are extremely important and are the basis of much discussion and effort by everyone concerned with the excavation of tunnels by machine. The second factor, just as obvious and equally important as an increase in boring rates, is "increase in production through better utilization of the tunneling machine and related equipment," which means a reduction in downtime through greater reliability of equipment. Mechanical rock attack is presently capable of cutting hard rock at 5 fph and soft rock at more than 20 fph. In current practice, however, this advance rate is maintained for less than 50% of the shift time. I predict that tunnel-driving contractors and their supporting manufacturers of tunnel-boring equipment will provide machinery that will maintain these advance rates for more than 90% of the shift time. This increase in effective production will be due to the increase in reliability of the tunneling machine and tunneling system components. Such a percentage increase in utilization of the tunneling equipment is just

Jan 1, 1970