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By Mario A. Terceros Herrera, Mario Terceros Arce, Antonio Marinucci

A Smart Cell is a closed-type tip post-grouting device that is attached to the bottom of the steel reinforcement cage of a drilled shaft and is used to enhance performance and to reduce uncertainty thereof. Control of the grout is maintained within the device during injection and a uniform stress is imparted across entire base area simultaneously, inducing a pre-mobilization load into the shaft as well as the soil. This paper describes the construction and tip post-grouting of drilled shafts from two bridge projects in the Santa Cruz, Bolivia region along the Paraí River. During the grouting process at each project site, there were noticeable differences in the grouting pressures achieved and responses observed, even within short distances between shafts. For this project, the greater benefit of using the Smart Cells was the reduction of risk and uncertainty of performance due to the highly variable soil conditions. Ultimately, since the response of each shaft was observed during grouting and because a “minimum” value of shaft resistance (i.e., pre-mobilization of load) was measured, there is a greater reliability with the anticipated performance of the shafts when axial loading is eventually applied.

By J F. Carswell, G Cheshire

The Pajingo gold operation in Queensland is approximately 55 km south of Charters Towers and 134 km south-west of Townsville. The gold deposit was discovered on the northern end of the Drummond Basin in 1983 and first open pit production began in 1986. Mining progressed underground in the 1990’s and gold production peaked in the early 2000’s as the main Vera/Nancy lodes were extracted, producing 330k oz in 2003 (a record at the time). More recently, as Ore Reserves and grade have diminished, the mine has had to develop innovative mining practices to maximise recovery of the remaining Mineral Resource. This has included a modified sublevel caving method against previously mined/backfilled zones. The method has been coined modified sublevel shrinkage (MSLS). Full scale trials of the new mining method have been successfully completed. This has allowed the site to revaluate the Mineral Resource and include areas into the Ore Reserve that were once deemed sterilised, adding significant value to the operation and extending its life-of-mine. This paper describes the first of two large scale MSLS trials and key operational learnings from it.

Mar 15, 2021

By Michael Jenkins

This paper reviews the history of rock burst research in the Coeur d'Alene Mining District of northern Idaho over the last 30 years. Rock bursting is a problem because of a combination of geological factors in the region--complex structure, high horizontal stresses, and strong, brittle rock that readily stores strain energy. The Bureau of Mines has cooperated with industry to study rock burst phenomenon for many years. Early work focused on methods to mitigate bursting problems within the context of existing mining methods. In the 1970's, researchers began investigating methods for altering or controlling conditions that lead to rock bursts. These control measures become part of the stope development that precedes mining or are changes in the mining process itself. Although, researchers continue to develop microseismic techniques, the major research effort focuses on developing a new mining method to reduce the number and severity of rock bursts in order to improve safety and increase productivity in the Coeur d'Alene Mining District.

Jan 1, 1987

By P. Favreau

This paper describes the progress accomplished at the Noranda Technology Centre in the field of three-dimensional computer-aided underground blast design. Traditional methods of laying out underground blasts are reviewed, and the new computer-aided approach is described. Time savings achieved through the use of BLASTCAD can be advantageously used to better engineer blasts, using models and blast vibration analysis. Future work involving the attachment of blast models directly to the system is also addressed.

Feb 1, 1993

By Charles V. Jenkins

The structure of steel, when rendered coarse by over-heating, is made fine by re-heating to a certain temperature, the determination of which has received much attention from eminent metallurgical authorities. Among these, I may particularly mention Prof. D. Tschernoff' [Chernoff], who, about thirty years ago, studied this question in connection with his investigations on the structure of steel in genera1. † Some years later, Mr. J. A. Brinell took up the inquiry, and arrived at many important conclusions, stated in his well-known rules on the treatment of steel. ‡ These two gentlemen, however, based their reasoning chiefly upon the aspect of fractures—a method which, though it affords valuable information, does not readily reveal the different steps by which a change in structure takes place. For further light on the subject, we owe much to more recent microscopic investigations, which have made us better acquainted with the internal structure of metals. Such an investigation, closely connected with the present subject, and made by Mr. John E. Stead a few years ago, was first published in 1898.6

Jan 1, 1903

By Francis X. McCullough

After OSHA published a Notice of Proposed Rulemaking on August 5, 1983, to revise its standards for Underground Construction, many contractors and their representative associations became concerned by the sweeping changes in the proposed rule. After reviewing all of the evidence and testimony on file with OSHA, the contractors presented extensive written and oral testimony to the Department of Labor in Washington, D. C. to help insure that the final published rule would be effective without jeopardizing the economic viability of the industry. The results of those efforts, the entire OSHA rulemaking process, and the opportunity for the construction industry to participate in that process will be discussed.

Jan 1, 1985

By J. L. Ellenberger, G. S. Esterhuizen, T. Miller, M. M. Murphy

A limestone mine in Ohio has had roof instability problems that have led to massive roof falls extending to the surface. This paper describes a collaborative study of these events undertaken by the National Institute for Occupational Safety and Health and the mine owners. The study focuses on the roles that weak, moisture-sensitive floor and weak bands in pillars play in a general instability that led to roof falls at this mine. The NIOSH Stone Mine Pillar Design software (S-Pillar) does not include analysis for weak floor or weak bands and recommends that when such issues arise they should be investigated further using a more advanced analysis. It is important to recognize that without the impact of the floor or weak bands, the calculated inherent stability factor for these pillars is within the recommended design range. Therefore, to further investigate the observed instability occurring on a large scale at the Ohio mine, FLAC3D numerical models were employed to help determine the failure mechanism. Roof-to-floor convergence monitors were also installed in the areas predicted to have further instability. This case study will provide important information to limestone mine operators regarding the impact of weak floor causing the potential for roof collapse, pillar failure, and subsequent subsidence of the ground surface. This recent case demonstrates that weak floor can be a significant factor in pillar stability and should be assessed during the design stage of the mine.

Jan 1, 2015

By P Holtham, K Duffy, B, W Valery, E Tabosa, rade

Pre-concentration has potential to significantly improve Mineral Resource efficiency by removing gangue early in the process, before energy intensive and expensive comminution and fine processing. However, there are numerous options for pre-concentration and the performance and benefits of these are very case specific. To determine the best option for a particular deposit and to successfully integrate it into the overall mining and processing operations requires comprehensive evaluation. This needs to consider orebody suitability, technology capability and economic viability. The in-situ variability of a deposit and how it is influenced by mining methods and the liberation size of gangue are key factors which are generally not well understood. Geostatistical methods provide an insight into orebody variability, and the overall selection of any pre-concentration solution must be an integrated approach between geology, mining and processing. Many pre-concentration evaluations investigate the potential of just one option. Technology selection should start wide and may include: selective mining, pre-screening (with or without selective blasting), sorting (bulk and or particle), coarse gravity separation (e.g. jigging, DMS), coarse particle flotation, magnetic separation, etc. The upgrade performance of these processes is very ore specific and should be determined from testing, with detailed multi-component modelling used to determine the overall process performance. Many of these pre-concentration processes require significant ancillary equipment, feed preparation and materials handling. It is important to realistically estimate all costs to understand overall economics and select the best option. Some examples showing evaluation and comparison of pre-concentration options are presented in this paper. These include assessments of in-situ variability using geostatistical tools, process modelling of pre-concentration options and overall performance, preliminary layouts and cost estimates, and economic evaluations.

Nov 10, 2020

By P Revell, G Wilkie, P Walters, L Keeney, F Faramarzi

Grade Engineering® is a value-driven strategy aiming to maximise benefits by exploiting intrinsic grade variability of ore deposits. It utilises a multitude of separation techniques to remove low grade material before being introduced to post-blast size reduction processes, i.e. crushing and grinding. At an operational scale, Grade Engineering® techniques can be implemented at the drill-and-blast stage, to control the degree of fragmentation in accordance with the spatial distribution of valuable minerals across an ore domain through differential blasting. It can also exploit intrinsic textural and breakage characteristics of a given ore type to reject uneconomical barren material at coarse sizes, which is known as Natural Deportment. Grade Engineering® can also be employed in the deliver stage of the mining value chain through sensor-based bulk and particle sorting. Each strategy is therefore highly dependent on the responsiveness of an orebody to available techniques. That is, the extent to which Grade Engineering® drivers would be capable of unlocking potential values of currently un-amenable orebodies depends on how detailed the heterogeneous nature of ore domains can be described. This paper considers exploring possible linkages between deportment characteristics of an ore and its competence when broken in a range of energy inputs at a particlebased level. Accordingly, potential opportunity may lie in exploring whether the intensity of input energy (or degree of fineness) can be used as a lever to improve or ‘unlock’ ore amenability to Grade Engineering® techniques. Implications from such a detailed approach offers new opportunities to enhance Grade Engineering® gains through engineering ore competence variability.

Nov 10, 2020

By Todd Minoski, Matthew McElhinney, Mark Mazzella, Morgan Sears, Craig Compton

The National Institute for Occupational Safety and Health (NIOSH) is staffed with Engineers, Geologists, and Field Technicians conducting a variety of ground control research. The mission of the ground control teams within the Mine Systems Safety Branch (MSSB) is to eliminate ground failures leading to mineworker injuries and fatalities. Advancing the science behind ground control relies heavily on conducting mutually beneficial research at participating mines which is detailed in specific references throughout the paper. The ground control teams have several types of field instruments at their disposal to measure the ground response in underground mines. These include borehole pressure cells (BPCs), vibrating wire stress meters (VWs), hollow inclusion cells (Hi-Cells), roof and rib extensometers, load cells, and convergence meters. These instruments are used to measure changes in pressure, strain, and displacement within the underground environment. Instrumentation data is collected automatically using intrinsically safe or MSHA permissible dataloggers if required. Information is transmitted to the dataloggers using approved cable to distances of 200–1,000 ft. depending on the type of datalogger being used. Once mining is completed, the dataloggers are retrieved and brought to the surface, providing in-mine data to mine management and engineers for the conditions currently being encountered in a particular mine. This data, in conjunction with geologic data and stress mapping, can be used to validate numerical models. The practical application of these models is extremely important for mine management and engineers, particularly when faced with more challenging mine environments. Insight gained from applying these models can be used to make better engineering-based judgments for areas that will be mined in the future. The impact of such applications can result in a reduction of ground-fall accidents and injuries as well as generally safer working conditions.

Feb 1, 2024

By C. W. Davis, M. W. Von Bernewitz, S. C. Lind

During the past few years our possible domestic resources of platinum have attracted much attention . On account of the extensive use of platinum during the World War , and the practical elimination of the Russian supply , the price of this metal rose to new high levels , as shown in Table 1 ; and though it since receded to some extent , the price is now nearly six times that of gold .

Jun 1, 1923

By Kadri Dagdelen, Lee J. Zamalloa

Modern surface mining operations are always seeking for minimizing costs while increasing production rates, among the optimization of other specific tasks that have an impact on the economics of the mine. Specifically, the cost related to the production fleet operation (shovels and trucks), the maximization of the overall performance of the equipment, and the uncertainty to meet the goals at the end of the operational time horizon are always topics of discussion with no apparent simple answer. On the other hand, truck-shovel dispatch systems based on Linear/Non-Linear Programming Algorithms have been in operation since mid-1990’s with different levels of success depending on the correct arrangement of operational resources and the complexity of the mine, but having in most cases some important shortcomings related to the way these systems deal with the decision making of the operational objectives, being necessary to have a human agent (dispatcher) to guide the system when the operational parameters change, creating the possibility of suboptimal decisions due to the human factor. This paper discusses the implementation of a novel methodology based on AI techniques to assist in the decision making of the best goal selection when operating a Fleet Management System, taking into consideration time periods as variables and integrating them as part of the analysis, providing a better overview of the forecast plan completion with respect to previous production numbers and evaluating best alternative to handle future events to minimize losses or maximize profits, resulting in better truck assignments, minimum shovel idle times and overall productivity improvements of the operation at the end of the time horizon.

Jun 25, 2023

By W. J. Fene, R. D. Currie

The value of protective clothing in the prevention of injuries has long been recognized in many of the leading industries , but the adoption of the idea into mine safety programs is comparatively new . Once started , however , the idea has grown rapidly and the results already obtained by mining companies have shown that it is fundamentally sound . Both coal and metal mining companies are rapidly adopting these protective measures , and since 1924 many mines have become well equipped with eye , head , and foot protection . At the present time approximately 70 percent of the employees in the anthracite mines of Pennsylvania are provided with safety hats . At many metal mines all employees are provided with safety hats, shoes , and goggles . The Pennsylvania mining law provides that all shaft · workers in anthracite mines shall wear protective hats . In According to a study³ made of the nature of 3,485 temporary injuries and of the parts of the body of underground coal mine employees most exposed to occupational hazards , the head and face were injured 665 times , the hands 856 times , and the feet 565 times . Of 2,555 temporary injuries in metal mines , the head and face received 484 , the hands 788 , and the feet 357 . a similar study4 made by a coal -mining company for the year 1928 , of 556 injuries the scalp received 9 , the skull. 4 , the eyes 47 , the hands 62 , the thumbs 21 , the fingers 141 , the ankle , the feet 51 , and the toes 35 . Probably most of these injuries could have been prevented by suitable protective clothing and equipment . This study also revealed that at least one injury occurred

Jun 1, 1933

By P. J. Mackey, J. B. See, D. G. C. Robertson

The production of iron and steel and non-ferrous metals by pyrometallurgical processes will remain a critical element in meeting the demand for materials in both developed and developing nations. Given the important need to reduce and minimise greenhouse gas emissions the technological focus of future pyrometallurgical R&D by universities and industry alike must concentrate on sustainability issues such as improved energy efficiency, recycling and waste minimization. Continued efforts are also needed on process optimization and new process development with a view to reducing capital and operating costs of the new large “mega” plants. Using the academic and industrial backgrounds of the authors, the present paper reviews the current status of R&D in pyrometallurgy in university departments with a particular emphasis on sustainability issues. The role of industry and government laboratories is also reviewed although primarily for developed countries. The paper also includes comments and suggestions on the future requirements for education and R&D in pyrometallurgy in developed countries to maximise sustainability. It is also suggested that future R&D in pyrometallurgy will be even more concentrated in developing countries – most notably China.

Jan 1, 2014

By C Simpson

In 2011 the forecasted world demand for iron ore continues to grow, and during this time Australia is looked upon as a reliable supplier of high quality ore. The expansion of the current Australian mines is unlikely to meet the forecast demand. New mines are therefore being actively explored for and when discovered, are quickly being developed into mines in order to meet the world’s hunger for steel.The Solomon Project area is a large new iron ore discovery, located in the central Hamersley Ranges of the Pilbara province in Western Australia. The first Fortescue exploration drill holes commenced on the project in 2007 and to date three billion tonnes (Bt) of iron ore have been defi ned within the project area. Fortescue is fast-tracking the development of the ‘Solomon Stage 1’ project, with rail and mine construction commencing during 2011, and ore to be railed to Fortescue’s existing shipping operations at Port Hedland commencing in 2012. At a designed production rate of 60 Mt/a, the Solomon operation will be one of the biggest production centres of iron ore in the Pilbara.Deposit types include the three dominant mineralisation styles of the Pilbara province, being bedded iron deposits (BID), Channel iron deposits (CID) and detrital iron deposits (DID). All these mineralisation styles are present in large concentrations within the Solomon project area, and when mined will produce two product streams. These are a single product of CID, and a combined product from a blend of BID and DID material.This paper defines the geological characteristics of the Solomon iron deposits as recognised through the exploration and development of this vast resource over the three years since exploration commenced on the project.

Jul 11, 2011

By Peter McKenna

Different reefs being extracted from a mine will, in all likelihood, have significantly different semi-variogram models - and these will probably vary from geozone to geozone. As errors of estimation are dependent on the semi- variogram parameters, it follows, if a mine samples all reefs in all sections using the same sampling grid pattern, that estimation errors (or limits of confidence) will not be the same throughout the mine. This may be an undesirable situation! A geostatistical study of the relative merits of alternative sampling arrangements has been carried out by considering different reefs in different sections of a South African gold mine.

Jan 1, 1989

By T. T. Toomver

The evolution of Inco's Selective Reduction Smelting Process as practised today is described, beginning with the initial laboratory experiments on small samples to the processing of large bulk samples through pilot plant equipment. For both the Guatemalan and Indonesian (Soroako) ores, the initial screening tests using hydro-, vapo-, and pyro-metallurgical processes showed that the latter was the most promising both metallurgically and economically. Later, larger scale tests confirmed the earlier testwork.

Jan 1, 1979

By François Robert, Steve Green, Tyson Birkett, Dan Richardson

Abstract -Detailed sampling using a portable diamond drill, and interlaboratory comparison of selected samples have been combined with statistical studies of truncated populations to establish the gold content of several outcrops in the Val d'Or area. The outcrops chosen are non-mineralized. The background gold concentration in the rocks of the region is 5 ppb or Jess. Gold is distributed relatively homogeneously within the outcrops studied except for slightly increased concentrations within quartz-tourmaline veinlets. Three samples, of which 20 grams of powder are analyzed for each, can adequately determine the gold concentration of a structurally simple outcrop in the Val d'Or area.

Jan 1, 1992

By T. Y. Chong, J. A. Folinsbee, M. Fullam

PJV Dome Mine has used some form of gravity concentration since start of milling operation in 1909 to recover free milling gold. Amalgamation and conventional jigs were first used and were replaced with the Knelson Concentrators in 1993. The Knelson concentrates produced were upgraded on a conventional shaking table prior to smelting and refining into gold bullion. In May 2002, a comprehensive review of the latest gravity recovery technology led to a piloting campaign aimed at further improving gravity recovery. The Knelson concentrates, subjected to intensive cyanide leaching in an Acacia pilot plant, were found to be amenable to intensive cyanide leaching with over 98% of the gold being dissolved within 24 hours. An Acacia Intensive Leach Reactor was successfully installed and commissioned in December 2002, to replace the shaking table. his paper describes pilot scale testing, installation, commissioning and optimization of the Acacia Intensive Leach Reactor. Also, the economic impacts on down stream processes are highlighted.

Jan 1, 2005

By E. Oraby, S. Garcia, A. Thurgood, D. Bertoldi, G. O’Malley

Mining and Process Solutions (MPS) most advanced process, GlyCatTM is the only process that can be easily adapted to existing cyanidation plants in the market today whose real advantages over cyanidation are when treating copper containing ores, concentrates or tailings. With such complex material, GlyCatTM requires 70-90% less cyanide addition to achieve the same precious metal extraction. However, GlyCatTM is not simply cyanidation with added glycine. It is a completely different process where the solution chemistry and conditions needed to effectively leach the precious metals are quite different. Downstream however, the process is largely unchanged as the recovery of the leached gold and silver uses existing known processes such as conventional activated carbon or zinc cementation (Merrill-Crowe process). Another advantage is lower SCN, OCN, WAD and no free cyanide in the effluent which can substantially reduce cyanide detoxification requirements and decrease the OHS and ESG risk of the operation. This paper outline some of these differences and presents testwork, piloting and process examples to highlight the advantageous of this new process over conventional cyanidation.

Feb 1, 2023