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By Meng Wang

"In this study, multiple methods that include geological surveying, laboratory studies, and numerical modeling have been used to study the deformation characteristics of a “deep inclined rock roadway with weak planes” (DIRRWP). Failure of the DIRRWP was found to be triggered initially by the shearing of the rock near the weak plane. The movement of the failed rock resulted in reduced confinement of the deeper rocks, and causing the failure of the supporting units and the severe deformation of the surrounding rocks. Hence, it is concluded that DIRRWP stability is affected predominantly by rocks near the weak plane. Corresponding control strategies for DIRRWP deformation were proposed: (1) greater support intensity is necessary to maintain the stability of the whole DIRRWP; (2) additional support is needed for rocks near the weak plane to reduce the potential of failure; (3) to increase the bearing capacity of the floor strata, as the floor needs to be supported; and (4) a supplementary support technique should be considered for cases of large deformation. The case study presented here indicates that the proposed control strategies can significantly reduce the potential of failure in rocks near the weak plane, thus preventing severe deformation of the DIRRWP.INTRODUCTIONAs shallow seams are mined out, the cover depths in most Chinese coalmines have become increasingly greater. Deep cover in a coalmine is considered to occur when the cover depth exceeds 800 m (Sun, Chen, and Miao, 2018). The loading and failure behavior of rocks in a deep cover setting are quite different from those in a shallow cover setting owing to the increase in in-situ stress, temperature, and hyperosmosis (Lobanova, 2008; Zhang et al., 2013). For instance, experience shows that bulking and dilating deformation in deep roadways is much greater than that which occurs in shallow roadways (Hou and Yang, 2018; Zhang et al., 2016). In addition, anisotropic behavior and thickness deviation of coal measure rocks, combined with the appearance of weak planes (e.g., faults, joints, and coal cleats) in coal and/or rocks, can significantly affect the stability of an underground roadway (Ghazvinian et al., 2013; Sun, Chen, and Miao, 2018). The presence of weak planes can significantly complicate displacement and stress transmission in nearby rocks. Additionally, tensile, compressive, and/or shearing failure in rocks near weak planes can be easily caused by high in-situ stresses in deep roadways; such failures may lead to further severe deformation of the surrounding rocks, resulting in roof falls and rib spalling (Kamata and Mashimo 2001; Wu, Ohnishi, and Nishiyama, 2004). A typical failure of the so-called “deep inclined rock roadway with weak planes” (DIRRWP) is shown in Figure 1. Severe deformation can be found near the weak plane. In this study, a plane or thin layer of rock/coal parting that can significantly reduce the strength of the surrounding rocks—and thus affect roadway stability—is defined as the weak plane."

Jan 1, 2019

By F. X. Ferney

The centrifuge which will be reviewed in this dis¬cussion is the continuous solid bowl typo. As there are presently approximately 2000 of these units operating in our country, and about 200 of these in use in the coal industry, I expect that most of you are acquainted with its operating principle. How¬ever, for those who are not familiar with the machine a brief introduction is in order. The continuous solid bowl centrifuge was first successfully marketed, worldwide by the Bird machine Company in 1934. The successful development of this unit was based primarily on the invention of a drive mechanism to properly control the differential speed between the two rotating elements. This centrifuge was introduced into the coal industry immediately following the second World War. Today there are five or six additional firms' selling this machine in our country, and approximately twenty others in Europe, England and Japan.

Jan 1, 1965

By Paulo Roberto, S. M. Roberto, Francisco Valadares Póvoa, Evandro C. Silva

The market of mineral goods worldwide is characterized by a growing pressure on suppliers for better quality products, lower prices and productive processes which are energetically efficient and environmentally friendly. These pressures force the mineral industry to re-think not only the present models of exploitation of natural resources and production, but also their own model of techno- logical development. This paper outlines the model and the experience of Technology Strategic Planning (TSP) adopted by CVRD to face these demands, warranting and expanding its participation in the current markets and developing new businesses.

Jan 1, 1998

By David Martin Menne, Chris Campbell-Hicks

Optimisation of many oxide gold processing facilities, in most cases, either does not really take place or if it does take place it happens too late or takes too long. This is unf01tunate as extra profits and early cash flows are lost, in new projects, and/or may not be realised at all in others. The situation is easily avoid­ed by ensuring that the plant optimisation happens immediately following commissioning or for an established operation simply 'biting the bullet' and making it happen immediately as a 'better late than never' decision. This type of optimisation requires intense undiluted focus on each and every problem or restriction that contributes to reduced plant performance or bottlenecks, without letting go, until the predetermined outcome is produced. Thus a dedicated person with specific quantative goals is required for these tasks. Methodology and strategies for optimi­sation are discussed and numerous examples presented. The secret of successful heap leaching is discussed.

Jan 1, 1998

By L. B. Kirk, A. R. Kirk

At New World, Au-Cu-Ag mineralization occurs in stratiform car-bonate-hosted, massive sulfide-iron oxide, and skarn-replacement deposits. Regional pyritic-alteration, local massive sulfide mineralization and mine wastes generate acid drainage within the district. Water quality improves down gradient through dilution and mixing of acid and metal-rich mine water with bicarbonate-rich, low-metal surface and groundwater, and precipitation of metal-rich ferrihydroxide phases. Natural deposits of ferricrete indicate that pre-mining ARD has occurred, providing important clues to pre-mining water quality. The geoenvironmental model identifies the Cu-skarn mineralization as the primary target for ARD management. Closure success will be limited by the geoenvironmental nature of the natural mineralization.

Jan 1, 2004

By Len H. Steele

To date VMD have designed, built and supplied nine autoclaves to various mining companies in Canada, the US, and Papua New Guinea. Initially, completely fabricated and lead lined units were shipped. The logistics of Placer Dome's Porgera PNG Project necessitated fabricating and lead lining each autoclave in five sections for transportation to site, each piece weighing approximately 30.5 tonnes. Support equipment such as turning rolls, automatic and manual welding machines had to be set up on site to facilitate assembly of these units which was a challenge in planning. This on site erection programme was completed in three months.

Jan 1, 1992

By Zhongxue Li, Shuang Gao, Zhixin Zhen, Yiqing Zhao, Xuan Qin

If not well-managed, a mine-tailings facility may become a major source of risks, endangering the community and environment, and damaging the reputation of the minerals industry regarding sustainability. Identifying, characterizing, and mitigating the hazards and risks associated with tailings facilities have been critical to the maintenance of community-safe and environmentally sound mine-tailings facilities. Herein, a complex network model for characterizing the hazards and risks associated with the lifecycle of tailings facilities is presented. In this approach, the hazards are modeled as vertices of the complex network, and the interactions among the hazards are modeled as edges of the complex network. The complex network for modeling the hazard and risk spreading of mine-tailings impoundments is analyzed and characterized by using network metrics such as the network density, geometrical characteristics, characteristic path length, network efficiency, and clustering coefficient. The degree distribution of the network obeys a power-law distribution, indicating that the network for characterizing the risk spreading associated with a tailings facility is scale-free. According to the results of calculations and existing research results, the network is ultrasmall-world. By analyzing the change of the global network efficiency under four kinds of different methods to remove network nodes and edges, network nodes with higher between centrality (BC) are identified as critical. The removal of those critical nodes helps mitigate risks associated with a tailings facility and reveals the vulnerabilities to BC attacks.

Jan 1, 2017

By James L. Whitlock, Amy E. James

During the past twenty years, numerous advances have been made in the technologies used to pretreat sulfidic refractory gold ores. These advances have included improved equipment design, increased gold recoveries, and reduced operating and capital costs. More recently, treatment of refractory gold ores has primarily been accomplished by pressure oxidation (POX), roasting, chlorine oxidation, or biooxidation. In addition to improving the time-proven processes of pressure oxidation and roasting, new and innovative approaches to biooxidation pretreatment of both concentrates and whole ores have been developed. Selecting the appropriate biooxidation technology depends on the nature of the refractoriness in the ore, economic gold recovery, plant design operating parameters (such as desired tonnage), site climatic conditions, and operating and capital costs, as well as several other deciding factors. The objective of this paper is to outline the biooxidation processes and technologies currently available for the recovery of gold from refractory sulfidic ores, to discuss the critical factors that affect plant design and operation, and to provide the metallurgist with a practical guide to choosing the appropriate biooxidation technology for a particular ore or concentrate.

Jan 1, 1999

By V. Svalbonas

In the establishment of a useful failure criteria for complicated, fabricated structures, two basic areas of knowledge must be evaluated: 1. The accuracy of the applied stress analysis must be known in comparison with actual stresses encountered during mill operation. 2. The metallurgical fracture properties of the basic materials must be established with reference to non-destructive examination (NDE) methods to be used during fabrication. Both of the above can only be evaluated by use of full scale tests on the structures, and/or components, of interest. This paper describes such tests and comparisons as applied to several large mill installations. In addition, weldment component fatigue tests arid flawed casting strain gauge tests are also discussed. The combination of such test results allows for the formulation of failure criteria directly applicable to the fabrication and examination procedures followed in grinding mill structure manufacture.

Jan 1, 1982

By Jacques Villeneuve, Stéphane Brochot, Jean-Claude Guillaneau, Marie-Véronique Durance

Since 1986, BRGM has been developing a powerful process simulation software package, USIM PAC. These last years have seen significant developments in mineral processing technologies, particularly in hydrometallurgy, bio-hydrometallurgy and mineral liberation. The new version of the simulator, USIM PAC 3.0, incorporates these modem-processing fields. Its structure and tools allow the user to take into account, at the same time, a wide range of technological, economical and environmental aspects. The improvement of the existing features and the introduction of new unit operation mathematical models and tools such as the supervisor, global optimization, workshop model or chemical reactions contribute to a global approach in mineral processing design.

Jan 1, 2002

By D. R. Barker

The economic performance and competitiveness of a concentrator are dependent on the production of accurate real-time assay information and the manner in which it is utilized. Our paper describes the relative merits of on-and in-stream analysis techniques and the economic significance of Assay-Based control and Target Oriented Display Systems. At Outokumpu's pyhasalmi Concentrator, a Flotation Expert Display System aids the process operator to make better decisions and provides guidance on the most efficient method of achieving the desired control objectives.

Jan 1, 1989

By R. W. Barbaro, R. V. Ramani

Generally, production planning is concerned with the best use of fixed resources to determine a production schedule for one or more production units supplying one or more markets. Production scheduling determines when each production unit will be used and its production level. However, the production scheduling problems are intimately associated with the location of existing or new production units and processing facilities. Normally, mine location allows only a limited choice; processing plant types and locations are considerably more flexible. This paper presents a generalized multiperiod MIP model as an aid in determining the mine production schedule and the processing plant types and location to satisfy multiple markets. A brief description of MIP and how it has been applied in the mineral and other industries is discussed. A complete description of the model with an application to a coal preparation plant system is presented.

Jan 1, 1987

By Viacheslav Lyakhov, Cornelis H. Iestra, Victor I. Beloborodov, Vitaliy Bogdanovich

The results of a study and effective use of flotation for processing of ores with complex mineral composition containing fine-disseminated minerals with high specific density are presented in the paper. The object of research was complex baddeleyite-containing ore from Kovdor deposit (The Kola peninsula, Russia). Baddeleyite is a valuable, rare mineral, natural Zirconium dioxide with 5.8 - 6.0g / cm density, grade content 0.15 - 0.17 and dissemination less than 0.2 mm. The authors carried out a thorough investigation of baddeleyite- containing products selected in different sites of gravity flowsheet. It was determined that due to similar specific weight some sulphide minerals (pyrite, pyrrhotite) come into concentrate together with baddeleyite and, also, minerals of pyrochlores group (hatchettolite). The results obtained revealed the possibility of use the flotation for retreating rough baddeleyite concentrate. he given gravity concentrate has a number of specific features, e. g. high density of its minerals which, in its turn, provides for high speed of sedimentation of solid phase in pulp, and for the presence of large amount of sulphide minerals (up to 10%) having good flotability. With these features being taken into account a technology for flotation of baddeleyite-containing products after their preliminary gravity concentration has been developed (up to 5 - 10% Zirconium dioxide). The technology has three flotation stages. At the first one the reverse flotation of baddeleyite is carried out during which "light" minerals (forsterite. apatite and carbonites) come into froth product and at the second one flotation of sulphide minerals and at the third one direct flotation of baddeleyite is performed from the underflow product. The following reagents were used for flotation: of phosphate type (sodium tripolyphosphate, mono and diethers of alkylphosphpric acid) and sodium xanthate as collector for sulphides. The given set reagents provides for high effectiveness of flotation due to selective of collectors and presence of froth layer with high carrying ability. New flotation technology of recovering of baddeleyite from complex ore was developed and applied at the Kovdor Mining Plant, using AKER flotation machines.

Jan 1, 1995

By Ralbern H. Murray

Typical First Year Selling Price Strip Mined Western Sub-Bituminous Coal Based [Fixed Capital (1) $600 MM Construction Loan Interest $100 Working Capital $ 30 Start-up Costs $ 30 Total Capital Requirement $760 MM Annual Costs (First Year) $M/Year Coal (2) 443,550 Operating Costs(3) 53,000 Depreciation(4) 36,500 Interest(5) 45,220 After Tax Profit(6) 34, 200 Federal Income Tax (48% Rate) 31, 570 Gross Revenue Required 245,040 (Less) By-Product Sales (18, 000) Net Revenue Required 227, 040]

Jan 1, 1975

By JOHN HOMER, KATHLEEN STABRYLA, JACOB L. CARR, JONATHAN K. HRICA, JENNICA L. BELLANCA

Given the recent focus on powered haulage incidents within the U.S. mining sector, an appraisal of collision avoidance/warning systems (CXSs) through the lens of the research literature is timely. This paper aims to evaluate the maturity of CXS technology through the application of a technology readiness assessment (TRA) to research literature identified by systematic search methods. Results indicate that much of the evidence for CXS performance is at lower levels of maturity: that is, components and prototypes tested in a laboratory and in relevant environments. Less evidence exists for CXS performance at higher levels of maturity — that is, systems evaluated within operational environments — despite the existence of commercial products in the marketplace. This lack of evidence at higher maturity levels within the scientific literature highlights the need for more peer-reviewed research to evaluate CXS technologies. Additionally, results of the review reveal that most of the literature relevant to CXS technologies is focused on vehicle-to-vehicle interactions, which contrasts with haul truck fatal accident statistics that indicate most are due to vehicle-to-environment interactions, such as traveling through a berm. Lastly, the relatively small number and segmented nature of relevant studies suggest there is a need for more incremental research that would better facilitate the improvement of CXS technologies. This progression could be achieved through continued long-term interest and support for CXS technology research.

Mar 1, 2023

By Michel Grenier, Mahendra Gangal

Two methods used to measure the exposure of mine workers to diesel exhaust particulate were compared. One method was developed by the U.S. Bureau of Mines and the University of Minnesota's Particle Technology Laboratory. The method which was originally developed for use in coal mines is a size selective sampling technique. The other method uses an “ashing" approach to assess the exposure to diesel particulate. This second method is based on the principles of sampling according to the ACGIH respirable dust sampling criteria and the use of a silver membrane filter as collection substrate. Because a silver membrane filter is used, both respirable combustible dust (diesel particulate) and respirable silica can be measured from one sample. The comparison study took place in a Canadian lead-zinc mine during tests which were primarily designed to evaluate the gaseous and particulate emissions characteristics of new diesel engine technology. The study has shown that under the test conditions encountered, some differences were observed between the results as obtained by the two methods. These differences seem to depend on the characteristics of the respirable dust found in the work- place, i.e., size and composition. The impact, on sampling and analysis of diesel particulate, of the proposed guideline (ACGIH) for a TLV® of 0.15 mq/m3 is discussed briefly.

Jan 1, 1997

By D. L. Kowal, P. J. Whittaker, M. A. Tuzun, N. O. Lotter

The area of flotation testing of drill-core is important in the business plan of most mining companies. Metallurgical information derived from this practice can be used to advantage in strategic decision-making. Sampling, flotation testing and subsequent Qem SCAN analysis of a mineral resource is one example of this approach. Anew resource, located in Sudbury, Ontario, is being assessed for the Sudbury Operations of Falconbridge Limited, which includes the Strathcona Mill. In this case, it was possible to improve the value of information from sampling and flotation testwork by using an improved, statistically-based test design, by sampling the resource by generic end-member ore type, and by integrating the Mineral Processing and Mineral Science disciplines into a Process Mineralogy team. In addition to producing standard metal grade and recovery information, this new approach provides more reproducible information from representative samples and flotation testing in a replicate format. Qem SCAN technology is used to produce a size by size mineral balance, including both modal percentages and liberation, from which flotation models for each ore type can be developed. As a result, a key understanding of the potential behaviour of a given ore type, if mined and then processed at the current mill operation, is gained at the 95%confidence level. The three ore types of this mineral resource were shown to have different flotation characteristics. Quantifying the mineralogy and liberation in each of the three ore types, has shown that this difference is due to changes in modal percentages of ferro-magnesium and magnesium silicate minerals such as pyroxene, talc and serpentine. Liberation across the three ore types is very similar and is therefore not responsible for variation in flotation performance.

Jan 1, 2003

By Yong Pan, SRIVATSAN JAYARAMAN SRIDHARAN, Purushotham Tukkaraja

The block cave mining method poses unique ventilation challenges compared to other underground metal mining methods. This research study focuses on assessing the airflow behavior in regulated airflow distribution systems by developing a 1:100 scaled block cave experimental model and a numerical model. This study also investigated gas flow behavior under various airflow conditions. Based on our findings, we observed that reduction in particle size and porosity of caved materials, decrease in cave footprint, and closure of undercut drifts would increase cave airflow resistance. The increased airflow is found to be beneficial for gas dilution regardless of its source locations, while the regulated airflow distribution system might deteriorate the gas dilution situation when the source is located in the extraction drifts.

Sep 1, 2022

By I. Iwasaki

There are many reasons why the US mineral and primary metals industry is in its present state. Undoubtedly, a flood of imported goods in all sectors is playing a major role in the plight of our raw materials industry. Domestic industry is becoming increasingly aware of the importance of its international competitiveness. And we are beginning to wonder what is happening to our technological edge. A number of factors affect the international competitiveness. Engineers cannot do much about some of these factors - labor costs, tax policy, government relations, interest rates, dollar strength, and labor-management relations. Something can be done about technology, however. Some say technology is so easily transferable today. But I would like to believe that we have the ability to apply it better than others. Not too many years ago, "made in Japan" meant cheap and shoddy products. Today, Japan has completely changed its image. The US is beginning to feel the threat from Japan's low-cost, defect-free products with dependable delivery. With worldwide recession and the strength of the dollar, we were shocked at the sudden weakness that developed in America's industries, not only in the international market, but domestically as well. What went wrong and what can we do about it? Senior executives from 300 large American manufacturing companies were surveyed. These executives believe US companies must: • invest in more efficient plants and equipment (27%); • invest in more research and development (23%); • improve the quality of service to customers (23%); and • adopt more aggressive marketing tactics and strategies (14%). Are we not doing enough research? The US has nearly four times as many people engaged in research and spends four times as much for research as Japan (Fig. 1). There is little doubt about the excellence of the US performance in basic science as indicated by the number of Nobel prize recipients. Japan has produced only four winners since World War II. Look at technology trade of five countries (Fig. 2). Again, US performance has been remarkable. An interesting observation here, is that the United Kingdom, another country with economic woes, is also in the black, West Germany and Japan, both with trade surpluses, are net technology importers. It is apparent that the US' performance in the commercialization of new knowledge is much more in question. Japan had $50 billion of trade surpluses with the US last year, which led to some friction between Washington, DC and Tokyo. Comparing the technology trade of Japan and the US in more detail, Japan imports disproportionately large amounts of technology from the US and Europe. This data is rather old, 1978, but the general trend is not too different even today. It is generally believed that scientific research leads to innovative technology, then to economic payoff. But, after seeing the current technological challenge by Japan, we are forced to change this traditional view. Investment in research may eventually lead to economic payoff, but not directly. There is a middle ground between new knowledge and its commercialization. This is an area where the Japanese have been successful. Until the 1970s, many western companies licensed patents to Japan for quick profits. But, in recent years, these companies have become more discrete about the terms of technological transfer. As a result, a number of scientists and engineers are expressing deep concern over the future of technological developments in Japan. A survey was conducted on 450 research managers of private industries in Japan on how they viewed the level of breakthroughtype original research in Japan as

Jan 6, 1986

By J. Reyher, R. Bratton, G. Luttrell, B. Li

"Flotation is regarded as the best available method of upgrading minerals and coal fines. However, its efficiency deteriorates rapidly with decreasing particle size. Further, ultrafine concentrates are difficult to be dewatered economically, forcing companies to discard part of the ultrafine materials to impoundments. To overcome these problems, a new method of separating and simultaneously dewatering ultrafine particles has been developed. Following extensive laboratory-scale test work, the process, known as hydrophobic-hydrophilic separation (HHS), has been tested successfully in continuous operations at proof-of-concept (POC)- and pilot-scale tests. The results show that the HHS process is capable of producing high quality clean coal with high recoveries and low moistures. INTRODUCTION Coal preparation plants are designed with up to four parallel processing circuits for treating coarse (> 12 mm), intermediate (12x1 mm) small (1x0.15 mm), and fine (<0.15 mm) particles. The plus 0.15 mm fractions can be effectively cleaned efficiently with gravity separation methods (Wills, 2006). At present, the only commercially viable option for cleaning the finest fraction is froth flotation (Yoon et al., 1999). In flotation, air is dispersed in the form of small air bubbles in a tank in which coal fines are suspended. The small air bubbles selectively collect the hydrophobic coal particles and float to the surface, forming a froth phase which overflows into a launder. As is well known, ultrafine coal particles of less than 30-50 µm are difficult to be collected by the air bubbles, resulting in low recoveries. Furthermore, fine particle flotation suffers from low carrying capacities and poor selectivity due to entrainment problems. (Bethell et al., 2005; Luttrell et al., 2014). In addition, the froth products containing ultrafine coal are difficult to dewater. Mechanical dewatering in general becomes inefficient with decreasing particle size due to small cake porosity and high surface area, resulting in high moistures (Hucko et al., 1988). The cost often becomes prohibitive with particles of smaller than ~45 µm (Bethell et al., 2005). Moreover, the high-moisture products are difficult to handle and incur high shipping costs and lower thermal efficiencies (Honaker et al., 2013)"

Jan 1, 2016