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By George Rice

Foreword Following the explosion in the Hillcrest mine, which occurred in the evening of Sunday, September 19th, 1926, and in which two men lost their lives, the writer was invited by the Hon. J.E. Brownlee, Premier of Alberta, to conduct an investigation into the causes of the disaster, and to make such recommendations as seemed advisable with a view to minimizing as far as possible the chance of future explosions in this and similar Alberta coal mines. Accordingly, the mine was visited, and extensive investigations were made underground on October 21st, 2.2.nd, and 25th, in company with Mr. John T. Stirling, Chief Inspector of Mines for Alberta, Mr. Moses Johnson, District Inspector for the Crowsnest Pass District, Mr. J as. A. Richards, Inspector of Mines, Edmonton, and also Mr. Thomas Davies, manager, and other officials of the Hillcrest mine. Hearings of the coroner's inquest were also attended on October 20th and 23rd, when testimony regarding the explosion was given by various witnesses. The following paper summarizes my general observations in tracing the place of origin of the explosion, and my efforts to determine the cause of ignition. Certain recommendations arc also made, and the writer invites discussion on these and the other matters dealt with in the paper.

Jan 1, 1928

By Chris Rule

This paper tells the story of the rapid commercial application of stirred milling technology at Anglo American Platinum?s many Concentrators. The first stirred mill ? a 10 000 litre IsaMillTM; the largest at the time, was commissioned in late 2003. The project development work was presented at SAG 2001. This operation was ?proof of concept? and vindicated the decision to scale up the technology; allowing a rapid and extensive roll-out of mainstream regrind mills as well as several further flotation concentrate regrind mills, over the next six years. Currently 23 stirred mills are in operation with 64 MW of installed drive capacity ? this paper describes the projects? roll-out and the significant results achieved to date. Many operational problems have been solved along the way, some of these will be described. The introduction of the technology has seen a step change in metallurgical results and progressively decreasing operating costs.

Jan 1, 2012

By E. Chin

Under the seventh 5-year plan (1986-90), the Chinese Government continued to implement reform and to open the country further to the outside world in order to accelerate the growth of its national economy. As a result of expanded foreign economic exchanges and domestic achievements in education, science and technology, and cultural and public health undertakings, the national economy was strengthened. In 1988, there was impressive growth in the Chinese economy. The gross national product (GNP) grew by 11.2070 reaching $373.4 billion; 2 the national income grew by 11.4070 to $310.9 billion. The major problem in the Chinese economy was the imbalance between high demand and insufficient supply. Chronic shortages resulted in price increases and high inflation, which averaged 19% for China as a whole and about 30% in urban areas. Macroeconomic stability took precedence over market-oriented reform initiative. Because of rapidly growing inflation, the Government re-imposed price controls and rationing in major cities in the fall of 1988. China continued to be a major world producer of minerals, metals, and fuels. Output of the principal commodities continued to rise. The largest in-crease in production was salt which rose 24% in output in 1988; followed by sulfuric acid, 14%; cement, 12%; soda ash, 9%; caustic soda, 7%; and steel, 6%. For fossil fuels, the increase in output of natural gas was 14% in 1988; followed by coal, 3%; and crude oil, 2%. The output of electricity by thermal-fired powerplants rose by 9% while that for hydroelectric power-plants rose 7%. Although China's overall energy output has increased annually since 1980, the growth in demand continued to outstrip the supply.

Jan 1, 1990

By C. Cornejo, C. Schuffeneger, J. Rosas

"At the end of 2010 the AMSA Esperanza Concentrator started commissioning. Located in the Atacama Desert this project is the first of several large size concentrators developed recently to operate in Northern Chile. In addition to the new operations to be implemented in the short term, many existing installations are planning expansions. The use of large size equipment is one of the common characteristics of the new concentrators, but also new technologies are being considered and innovation is present in most cases. Sea water or desalinated water will be required to process large tonnages of sulphide copper ores as well as gold bearing ores, since process water supply from the Andes will no longer be available. The high cost of sea water or desalinated water supply and the high cost of energy are not a limitation as the current metal market scenario allows obtaining an attractive NPV even from installations designed to process relatively low grade ores. A review of the current concentrators being developed in Chile is presented, including a description of the main design issues related to technology and innovation. An analysis of the Chilean mining industry is also presented, detailing mine and plant capacities as well as expected final products.INTRODUCTION The mining sector in Chile has become a reference when analysing the large concentrator plants projected or currently in operation all over the world. At present and as a consequence of the high price of metal commodities, most South American countries have an active mining sector. Chile is known as a major producer of metals. First records of copper production exported to Spain are dated to the early XVII century. Since then Chile has produced over 13% of the total copper ever produced in the world. After 1990 Chilean mining and the associated cluster of activities has substantially grown to levels never reached before, especially in the production of copper, gold and other non-metallic minerals. This dramatic increase is the result of an economic policy based on delivering comparative advantages and incentives for the admission of foreign capital to offset the weak domestic investment in previous decades. Massive mining of its huge mineral resources has allowed Chile to be a world leader in the production of copper and other base metals and mineral products."

Jan 1, 2012

By Aleksandar D. Bugarski, Robert J. Timko

Despite extensive research efforts conducted in the past decades, occupational health risks associated with exposure to nano and ultrafine aerosols emitted by diesel power equipment are still not completely understood. The complexity of physical and chemical properties of diesel aerosols, constantly changing with the implementation of advanced diesel emissions control technologies, make this task rather challenging. The objective of this paper is to identify and characterize nanometer and ultrafine aerosols emitted by diesel engines in the underground environment and evaluate the effects of selected contemporary control technologies on physical properties, chemical composition, and in-vitro toxicology of diesel aerosols. The physical and chemical properties of the nanometer and ultrafine diesel aerosols are to be characterized through a test series in the NIOSH Lake Lynn Laboratory experimental mine. The crucial part of the study has been development of a facility that allows researchers to generate field results with precision and accuracy characteristics of a laboratory environment. The knowledge obtained from this study should strengthen our understanding of the health implications related to exposure to diesel particulate matter and aid in assessing the potential of various control technologies for reducing this exposure.

By Inn-Joon Park

Major problems associated predicting soil-structure interaction behavior are based on the fact that soil is neither homogeneous nor elastic and soil properties are spatially variable. There also exist significant coupling problems between the behavior of the structure and geologic media. When designing foundation or other geotechnical structures, the load transfer between the soil and structure takes place at the contact surface. This surface is called the interface. The behaviors of interface play an important role in the load-deformation response of soil-structure interaction systems. The purpose of this study is to develop improved model for simulation of saturated sand-steel pile interface behavior based on a general concept, called the disturbed state concept (DSC), which can characterize the behavior of saturated soils under dynamic loads. In this study, the Disturbed State Concept (DSC) constitutive model is calibrated and modified for steel pile-saturated sand interface and interaction by using the continuous hardening model for relative intact (Rl) state and the critical state model for the fully adjusted (FA) part in the saturated sand material. The general formulation for implementation has been developed. Then, the DSC model with modification for interface and saturated sand is implemented in finite element program based on the generalized Biot's theory. The interface tests under one-way monotonic and two-way cyclic loading and cyclic triaxial tests are executed for defining the parameters for interface and surrounding soils. Based on these parameters, steel pile-saturated sand interface and interaction are numerically simulated using the finite element program modified in this study. The DSC predictions show improved agreement with the observed results from laboratory test.

Jan 1, 2002

By V. Yahorava

Resin-in-pulp (RIP) technology has recently often been considered for the direct recovery of base metals and uranium from dense pulps. Implementation of RIP will eliminate the requirement for any solid-liquid separation downstream of leaching and has the potential to combine the recovery and purification steps, hence reducing both capital and operating costs. The recovery of the valuable metal is expected to be higher when RIP is used, especially where the leached solids are difficult to settle or filter, and to wash. The main concerns about the use of RIP for uranium recovery from dense pulps are the impact of silica on the resin?s metallurgical performance and the operating costs that would be associated with resin loss. Although a number of resin manufacturers have been developing much improved RIP-grade resins, it is critical that the most cost-effective resin be selected. Mintek currently is doing a significant amount of work on silica fouling of RIP-grade strong-base resins in acidic leach liquors and the effect it has on the performance of the resin, including its durability. This paper describes the results of the test work done on silica fouling and its impact on plant design input data. Resin durability test work was done using various laboratory techniques, but durability was also evaluated on a relatively large scale using actual pumps, screens, and mechanical agitation. Based on the results generated, a preliminary economical evaluation was done to estimate the impact of resin loss on the overall economic viability of a specific application. Keywords: resin-in-pulp, silica fouling, resin loss, equilibrium, kinetics, elution, durability, mechanical strength, resistance to attrition.

Jan 1, 2009

South Africa remains the largest global producer of gold, accounting for 11.3 per cent of total world mine production, which amounted to 2520.2 t in 2005. The benefits and disadvantages associated with hedging practices in general, and among South African gold producers is examined. The wide variety and unique nature of risks faced by the mining industries provide a strong case for hedging. Only the principles of hedging, such as selling ounces of gold in the ground at a pre-agreed price for delivery at a future date as a cost-effective mechanism for price risk management, is discussed. Progressive and cumulative increases in the volume of forward sales in the major producing countries are considered by many to be the cause of the declining gold price over the past decade. In spite of negative publicity, forward selling continued as an industry-wide practice until recently (2002) when the global hedge book contracted by 352 t; contraction amounted to 158.6 t in first quarter of 2006. The objectives and benefits of hedging include continuity and stability of cash flows, stability in price achieved, reduction of frictional costs, and creating an effective management tool. The importance of a defined hedging strategy in reducing uncertainty about the hedging objectives is essential to a successful hedging policy. Historical patterns in hedging revenues at an industry level indicate five distinct periods during which the fortunes of hedgers have fluctuated. Finally, since 2001 the rising gold price and reduced price volatility through the consolidation in the global price means that the need to stabilize revenue flows is less urgent. This has meant that hedging is becoming progressively less important for the mining industry at large.

Jan 1, 2007

By Frank E. Cash

Although during the past 10 years Alabama has attained an enviable position by its coal-mine accident experience and, like most of the other coal-mining States, has made progress in the safer operation of coal mines, there is still room for improvement, which can be realized only by still greater efforts on the part of employees and employers. From 1993, when accidents were first recorded by the Alabama State Mine Inspection Department, to 1934, inclusive, 3,451 men lost their lives in the production of 569,722,676 tons of coal. The primary purpose of this report is to bring to the attention of the mining industry in Alabama end elsewhere statistics of fatal accidents for 1931-34, with the hope that a study of the causes may lead to reduction of similar accidents in the future.

Jan 1, 1936

By Donald Leroux, Ralph Dahlke, Dave Scott, Finch. James A., Cesar O. Gomez

"The efficiency of the flotation process depends on how effectively air is dispersed into small bubbles. Bubble surface area flux - the surface area of bubbles per unit time per unit cross-section area of a cell - is emerging as the parameter to characterize gas dispersion. One of the approaches proposed to measure bubble surface area flux in industrial cells is based on the measurement of two variables: gas velocity and gas holdup, using separate sensors. Plant testing of the gas velocity sensor gave evidence of a series of operational problems which may be necessary to correct before attempting to characterize gas dispersion. Problems such as uneven air distribution within a cell and along a bank, faulty air and slurry valves detected during attempts to redistribute air, and poor control of pulp level and gas flow became evident. Detection of these problems from gas velocity measurements is illustrated.INTRODUCTIONBubble surface area flux is considered a key variable in the optimization of flotation circuit performance (Gorain et al., 1997; 1998). The Mineral Processing Group at McGill University has devised and developed a method for estimating bubble surface area flux in industrial flotation cells (Finch et al., 1999). The method is based on measuring gas holdup and superficial gas velocity using two separate sensors and applying drift flux analysis to estimate bubble size (Dobby et al., 1988; Banisi and Finch, 1994). With bubble size and superficial gas velocity known bubble surface area flux can be calculated.This method was selected by Noranda to characterize gas dispersion in cells as part of a program to model and optimize flotation circuit performance. However, initial testing at Brunswick Mine with the gas velocity sensor provided some unexpected results indicating operational problems and equipment malfunctions that needed to be addressed before systematic measurement of gas dispersion could be initiated.The subject of this communication is to illustrate the detection of these problems from gas velocity measurements. The line 3 Zn Cleaner circuit comprising four stages of Denver DR cells was the main subject of analysis, including the effect of correcting these problems on the metallurgical performance of the Zn 3rd cleaner bank of ten DRl 00 cells."

Jan 1, 2001

[Pumps: oil-well: plunger: essential parts, G26, 130; 74, 828 improved type, 74, 846 leakage, 74, 837 operating cycle, 74, 833 Uren design, G26, 145 sucker-rod failures, G26, 136 sucker-rod stress, 74, 835 sucker rods, 74, 830, 832 tubing, 74, 833 tubing difficulties, G25, 138; 74, 836 Olivite, 73, 337 valve and seats, 74, 832 Punching: Monel metal, 78, 86 nickel, 78, 86 Punjab. See Indian Empire. PUPIN, M. L biography, M26, 113 John Fritz medalist, 1931, M81, 499 recipient of Washington Award, M28, 155 PURDY, R.: Discussions: on Relative Efficiencies of Domestic Fuels in Relation to Their Costs and Their Advantages 108, 353 on Uses on Coal in the Ceramic Industry, 108,389,398]

Jan 1, 1936

By Alexander J. Verstraeten

Work started on the building of the Amsterdam Concert Hall in 1880 by driving over 2000 wooden piles of 13 m on which foundation-beams out of wood and brickwork were made. During construction the design was changed. This was due to the latest German developments, requiring double walls instead of single, so that the space in between could be used for ventilation and heating. Therefore the pile load, originally designed at approximately 100 kN, increased even to 170 kN for some piles, causing settlements and unacceptable cracks in the brickwork. Settlements of up to 18 cm were measured. In 1985/1986 around 400 vibration-free Tubex-displacement-piles were installed under the Concert Hall, with a shaft of 0355 mm, a pile shoe of 0560 mm and a pile length of approximately 18 m. After these Tubex piles had been installed they took over the complete weight of the whole building, thus eliminating further settlements and damage. 95% of all the construction activities took place while the concerts went on. The chosen solution also made it possible to create a new basement under the Concert Hall as an extension for dressing-rooms etc.

Jan 1, 1987

By William R. Yernberg

The combined 76th Annual Minnesota Section of SME meeting and 64th Annual University of Minnesota Mining Symposium were held April 8and 9, 2003, in Duluth, MN. This year’s theme was “Stakeholders, Partners in Change.” The meeting included four keynote speakers, technical presentations and a tradeshow. Engineers, executives, mining managers and suppliers from throughout the United States and eastern Canada attended the meeting. Reflecting the theme of the meeting, all agreed that the mine owners, the government, the community and the employees are all “stakeholders.” They must be “partners in change” for the iron ore mining industry to survive in the region. Compared with past meetings, where improved technology was the primary focus, this year the focus was on the dramatic restructuring of the entire industry. As noted by several of the speakers, “This time, the change is not in technology.”

Jan 1, 2003

By Kevin Beirne

Most people involved in the mining industry are familiar with student-industry co-op work-study programs. Many colleges and universities have used them for years. Northern College’s Haileybury School of Mines student co-op program adds a new dimension of productivity to the college and the mining industry. The college is located in Hailey-bury, Ontario, Canada. An example of the program’s success is the school’s relationship with Sabin Metal’s SMC (Canada) Ltd.’s McAlpine Mill in Cobalt, Ontario. Students gain practical knowledge and experience while industry gains an eager-to-learn worker. And many of the college’s advanced research services are made available to industry to supplement their own capabilities. The McAlpine Mill was established to provide custom milling of slags and ores. It also recovers metal values from other products of the primary and secondary precious metal industries.

Jan 1, 1999

Measurements from an old survey are being machine processed as a pilot project in the development of a computer-assisted method of structural mapping in shield areas. The key element in the system is a field data sheet which requires the geologist to determine a textural hierarchy in each exposure. The pilot system is limited to orientation analysis and utilizes a prior textural analysis, but this would not usually be a problem in utilizing the system ab initio for exploration. A data processing system of this general type offers promise of considerably increased productivity of field geologists by reducing compilation time and improved technical supervision through centralization of processing, and would make structural analysis an economically viable tool in mining exploration and development.

Jan 1, 1969

By Roy A. Imbsen

Following the 1989 Loma Prieta earthquake, California Department of Transportation (Caltrans) expedited an effort to evaluate and retrofit important state-owned toll bridges to en­hance performance of the state's transportation systems during and after major (credible) earthquake events. Imbsen and Associates, Inc. (IAI) along with their sub-consultants, were awarded a contract to conduct seismic evaluation and to develop retrofit design for Benicia-Martinez Toll structure, to meet a "Serviceable" performance requirement after the event of a "Safety Evaluation Earthquake." This paper describes the design and construction specifications for the deep foundations supporting the main spans of the Benicia-Martinez Bridge. Benicia-Martinez Toll Structure (George Miller Bridge), a high-level deck-type welded truss bridge with welded girder approach spans, carries Interstate Route I-680 over the easterly end of Carquinez Strait near San Francisco, CA. The nearly 5000 ft long main truss structure consists of ten spans, ranging from 330' to 528' in length, supported on cellular reinforced con­crete pier structures. Foundation systems across the waterway, consist of cellular reinforced concrete footings, supported by groups of 6' diameter, concrete filled, steel caissons, resting on 5' deep rock sockets, at depths of 50' to 150' below the water level. Seismic evaluation of the existing foundation systems accounted for spatially varying ground motion along the length of the structure, variability of foundation material strength (i.e. at bed-rock), variation and effects of scour depth on the performance of the foundations, and dy­namic soil-structure interaction. Performance of caissons beyond their elastic strength, as well as their effects on the behavior of the foundations and substructures were evaluated and considered in establishing foundation vulnerabilities. Several retrofit strategies were considered leading to a final retrofit strategy to strengthen end connections of existing caissons, as well addition of new caissons to provide adequate lateral force resistance for the foundations. Final design package includes specifications as well as construction methods and requirements for existing and new caissons, under traffic, and pile load testing procedures for design loads of up to 12500 kips per caisson.

Jan 1, 1998

By Frank Callanan

The Ameristar Casino expansion project included the design and construction of a 25-story hotel and 9-story parking structure expansion. The site is located in a floodplain on the banks of the Missouri River in Saint Charles, Missouri, where the underlying soils are potentially liquefiable. The geotechnical engineer performed subsurface exploration and analysis, which included site-specific seismic response and liquefaction, and provided geotechnical design recommendations. In the event of an earthquake, post-liquefaction settlement was calculated to be approximately 14 inches. Additional project constraints included wetlands protection, construction adjacent to the existing facility, flood protection and river bank stability. Because of the liquefaction issue, the geotechnical engineer consulted with a specialty geotechnical contractor on ground improvement methods. This consultation led to a proposal to eliminate deep foundations from the design and support the structures on shallow and mat foundations. The geotechnical engineer assisted the design team with foundation design analysis and value engineering assessments. Together with the project team, the geotechnical engineer used the data to evaluate foundation options and construction methods to overcome the site challenges and concluded that ground improvement was the optimum course of action. Because of the nature of the site constraints, a number of ground improvement methods were needed. The geotechnical engineer evaluated the methods proposed by the geotechnical contractor and provided the technical specifications for the ground improvement bid package, which included vibro-compaction, compaction grouting and micropiles. The ground improvement allowed for the use of shallow foundations (mat and spread footings), which provided the client with significant time and cost savings over the deep foundation alternatives.

Jan 1, 2009

By Ivette E. Torres

Aruba, formerly a. part of the Netherlands Antilles, separated on January I, 1986, and became an autonomous part of the Netherlands. Full independence of the island from the Netherlands is scheduled for 1996. In this chapter, however, Aruba's statistics are included with those of the Netherlands Antilles. Tourism continued to be the main industry of the island, which continued to depend heavily on imports, mostly from the United States. During the year, the Government was preparing legislation to regulate the exploration of oil deposits in the relatively shallow sea around Aruba.

Jan 1, 1989

By W Akpan

The Royal Bafokeng community in South AfricaÆs North West Province represents a unique case in Sub-Saharan Africa in terms of its positioning in the natural resource economy. It receives royalties directly from mining firms for the extraction of Platinum Group Metals, which include platinum, ferrochrome, rhodium and palladium. In 2007, royalty income of about R290 million (approximately US$32.2 million) was reported. Such direct revenues have enabled the community to invest in educational, medical and other social infrastructure, thus complementing governmentÆs social provisioning efforts. Indeed, the Bafokeng community owes its present-day modernisation efforts to mineral rights, and in particular, the legal-institutional arrangement that has enabled it to play an active role in South AfricaÆs lucrative extractive economy. However, the distribution of platinum wealth in this community is not only uneven, but also appears to have had little impact on the broader socio-economic conditions in the community. Despite claims by community leaders of heavy investment in education and skills development, the community continues to be faced with very high levels of unemployment, illiteracy, sprawling informal settlements, poor access to medical facilities and malnutrition. This paper examines the sociological paradoxes and contradictions thrown up by the approach adopted to involve community members in the mobilisation of mining royalties for developmental ends. The central argument is that the current æmodelÆ contradicts the communityÆs stated goals of using platinum wealth to drive up broad-based development and modernisation. This is mainly because it leaves out the vast majority of community members, who are uneducated and unskilled. The core analysis is based on pilot data from an ongoing study in the Royal Bafokeng community.

Jan 1, 2009

By Lu Li, Sara E. Wilson

Occupational exposure to whole body vibration has long been associated with increased incidence of low back pain and low back injuries1. A number of studies have investigated transmissibility of seat pan vibration 5, 6. While transmissibility has been well researched, the mechanism by which vibration may induce injury has not been thoroughly studied. Winter et al. identified increased reflex response delay after vibration exposure and speculated that muscular fatigue may be the cause of this increase9. However, a mechanism has yet to be demonstrated completely. A potential mechanism that may explain the increased risk is neuromotor habituation. Muscle spindle organs have been shown in the extremities to be sensitive to muscle and tendon vibration. Rapid length changes in muscle have been shown to result in kinesthetic illusions as the regular firing of the muscle spindles is interpreted as muscle lengthening4, 7. These illusions have also been demonstrated in the paraspinal musculature2. With removal of vibration, research in the extremities has demonstrated increased positioning errors, probably due to neuromotor habituation8. In this research, it has been hypothesized that neuromotor habituation after exposure to occupational vibration will increase positioning errors. It is further hypothesized that these errors can be shown to be linked to increased reflex response time. Such increased reflex response time could, in turn, decrease spinal stability and increase low back injury risk. Methods Both positioning error and sudden load response were measured before and after exposure to 20 minutes of 5 Hz, 0.223 m/s2 RMS seat pan vibration. Subjects were asked to sit on an unpadded seat without a backrest. Throughout the whole body vibration period, subjects were instructed to put their hands on a stable hand rest and feet on an adjustable stable footrest. The subjects were instructed to assume a comfortable and relax sitting posture for the duration of the exposure. Positioning error was measured using an active-active reposition sense protocol. Electromagnetic markers (Motionstar, Ascension Tech, Burlington, VT) were used to track trunk motion. With markers attached to the skin at the T10 vertebra, the S1 vertebra and manubrium, trunk flexion (the angle from vertical of the line connecting T10 and S1) and lumbar curvature (the difference in inclination of the T10 and S1 markers) were tracked. In the reposition sense protocol, subjects were asked to maintain an upright trunk flexion and to rotate their pelvis and lumbar curvature to assume a target lumbar curvature. In the protocol subjects completed training trials, where they were asked to match their lumbar curvature using a visual display, and assessment trials, where they were asked to reproduce the lumbar curvature from memory. After two initial training trials, training trials and assessment trials were alternated for a total of 3 assessment trials. Reposition error was defined as the absolute difference between the target lumbar curvature and the lumbar curvature the subject assumed during the assessment trials.

Jan 6, 2006