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By Jack S. Watson, Rasika Nimkar, Robert M. Counce, Matthew Gordy, Patrick Zhang

Waste phosphatic clay presents a difficult disposal problem and a significant loss of P2O5. Recent developments make this study on the use of phosphatic clay as a feed material for H3PO4 production worthwhile. (a) New data from Florida Industrial and Phosphate Research Institute (FIPR) suggest that the Bclay^ waste can be effectively treated by improved solid separation coupled with flotation to produce feed material for recovering additional phosphate. (b) The use of BOLI Flowsheet^ provides capability to predict performance of aqueous-based processes for a range of possible operating conditions. Using the new FIPR data and BOLI Flowsheet^ enabled the design of a new process that can potentially extend the usefulness of current P2O5 ore deposits. Predictions using OLI Flowsheet were able to identify process conditions that effectively overcome the difficulty of high Mg content of phosphatic clay. Estimated manufacturing cost in the current study lead to valuation of the P2O5 content of the phosphatic clay recovered/utilized at 60 to 70% of that of the phosphate rock feed material currently used. Phosphatic clay should be considered as a valuable material that is currently given zero value. The new FIPR data and BOLI Flowsheet^ enables the design of a new process that can potentially extend the usefulness of current phosphate ore deposits by extending the fraction P2O5 of recovered

The Canadian mining industry is one of the strongest in the world. Not only does the country produce a sizable amount of minerals and metals, Canada plays host to hundreds of global mining companies, large and small. The country, for the most part, recognizes the importance of natural resource development, particularly mining, to its economic well being. Like any country, though, there are federal and provincial regulations on the books that the industry takes issue with. But there are also certain economic incentive programs in place to encourage exploration and mine investment. And, unlike the industry and the United States government, the Canadian government and mining industry appear to have a reasonable working relationship.

Jan 4, 2010

By N. Wahl, D. M. Blackketter, R. Thornton

This paper evaluated using a water-filled abandoned mine (Orphan Boy) as a heat source for a 240- kW closed-loop heat pump with the goal of heating a 2,000-m2 building. The mine has a 245-m vertical shaft connected to a large stope by three horizontal cross-cut shafts. There is 1,250 x 106 L of water at a consistent temperature of 24-26° C that is available mostly in the stope. The only heat exchanger placement option is in the vertical shaft. Therefore, the focus was to model heat exchanger placement in the vertical shaft to determine the extent to which the systems will induce thermal currents between the stope and vertical shaft. Modeling of thermal currents, temperature profiles and heat contribution from the ground was done using finite difference and computational fluid dynamics. An optimal configuration was determined showing sufficient water movement and heat transfer will occur with a low water temperature in the shaft above 20° C. This project supports a U.S. Department of Energy (DOE) grant that will implement the full-scale system.

Jan 1, 2013

By L. Yuan, J. H. Rowland, D. Bahrami, R. Thomas

Blasting is the main method of production in many non-coal underground mining operations and produces multiple toxic gases as a result. The Mine Safety and Health Administration (MSHA) requires mine operators to measure the level of toxic gases in mines as frequently as necessary to ensure they are below regulatory safety limits. The current practice uses portable gas monitors to check the concentrations of toxic gases after a fixed post-blast time. This paper studies the application of a gas monitoring system in the return entry of a limestone mine to determine a safe re-entry time. The National Institute for Occupational Safety and Health (NIOSH) conducted such a monitoring program in a limestone mine from September 2016 through May 2018. NIOSH/PMRD (Pittsburgh Mining Research Division) is endeavoring to develop workplace solutions to improve detection of and reduce the risk of hazardous conditions. This study showed that the use of gas monitoring in the return air can be a useful tool at the mine operator’s disposal to detect and reduce the risk of hazardous conditions and also to reliably estimate the re-entry time.

By Wendy M. Brunner

A 70% excess of mesothelioma, an asbestos-related cancer, has been reported among men in northeastern Minnesota, where iron mining has been the major industry. The Minnesota Department of Health has studied iron miners who developed mesothelioma to identify possible sources of asbestos exposure. A database of all Minnesota residents diagnosed with mesothelioma between 1988 and 1996 was linked to a database of approximately 72,000 current and former Minnesota iron-mining employees to identify cases who had ever worked in the mining industry. The job histories of the cases were examined to determine if any of their jobs could have involved exposure to commercial asbestos. Seventeen individuals diagnosed with mesothelioma in Minnesota between 1988 and 1996 were found to have worked in the iron mining industry. Of the 15 for whom adequate work histories were available, 14 had identifiable sources of exposure to commercial asbestos in jobs held both inside and outside of the mining industry. The time between employment in these asbestosexposed occupations and the diagnosis of mesothelioma is consistent with the 20 or more year latency period that has been observed in other studies of this cancer. © 2007 Elsevier Inc. All rights reserved. Keywords: Mesothelioma; Asbestos; Iron miners; Taconite; Epidemiology; Case series

Jan 1, 2007

1. Paper1?Identification and enumeration of asbestos fibers in the mining environment: mission and modification to the federal asbestos standard Arthur M. Langer Asbestos-related disease is increased with cumulative exposure (the concentration of asbestos in the air and duration of exposure). The maximum duration is assumed to be a working lifetime so federal agencies control cumulative exposure by limiting the airborne concentration of asbestos fibers equal to or greater than 5 lm in length. Air samples are collected in the environment of interest by entraining the airborne particulates including fibers on membrane filters and then counting the number of fibers using phase-contrast light microscopy. In addition to length, the fibers must have a length to width ratio of at least 3 to 1. This ratio is also referred to as the aspect ratio. Some counting strategies placed an upper limit on the fiber width restricting the counting to respirable fibers. Airborne asbestos is controlled by monitoring a sub-population of the airborne asbestos. No asbestos fibers shorter than 5 lm or fibers of any length having widths less than the resolution of the light optical method are counted. In the non-occupational environment, the Environmental Protection Agency requires the use of analytical transmission electron microscopy and fibers and counting fibers with lengths of 0.5 lm or greater and aspect ratios of 5 to 1 or greater are counted. The permissible exposure limit for asbestos has been reduced by more than 120-fold since 1969, when the standard was 12 fiber/ml and the current monitoring methodology was developed. The manufacturing and mining worksites are regulated by two different federal agencies and the asbestos exposure limit was higher in the mining environment until recently (Mine Safety and Health Administration 30 CFR Part 56, 57, and 7, Federal Registry, February 29, 2008). Currently the permissible exposure limit (PEL) is the same in both types of workplace and it is 0.1 fibers per milliliter (fiber/ml) over an 8-h shift as a time-weighted average (TWA). A milliliter (ml) is equivalent to a cubic centimeter (cc) and sometimes this standard is reported as 0.1 f/cc. As the phase-contrast methodology was used to monitor lower exposures and environments, other fibrous mineral particulates were incorrectly characterized as asbestos. These occurred in talc deposits and taconite ores from the Eastern Mesabi Range.

Jan 1, 2008

By Manuel Pérez-Tello, María M. Salazar-Campoy, Óscar Rodríguez-Hoyos

A common problem during the operation of the Kaldo furnace is the formation of accretions and blockage of the injection lance due to splashing. This typically occurs during the processing of anodic slimes for the production of doré. In this work, a 1:7 scale model of the Kaldo furnace currently in operation at Metalúrgica de Cobre, Mexico, was built in transparent acrylic plastic. Water and colored oil were used to represent the doré and slag, respectively. The model was used to determine the maximum penetration distance of the injection lance under a variety of experimental conditions at room temperature. Input variables included two types of oil, rotation speed, inclination angle, and the fraction of the vessel volume occupied by the liquids (φ). A mathematical correlation for the dimensionless maximum penetration distance of the injection lance d ∗ as a function of φ, the Froude number of the liquids in the vessel (Fr), the Reynolds number of the gas jet (Re), and the oil-to-water kinematic viscosity ratio (η)was developed. Reasonable agreement between the calculated and experimental values was obtained. Digital images showed that splashing was caused by the turbulent gas jet impinging upon the free surface of the liquids, whereas the cascade effect was negligible. The results of this work have been useful to improve the operation of an industrial Kaldo reactor.

By Manuel Pérez-Tello, María M. Salazar-Campoy, Óscar Rodríguez-Hoyos

A common problem during the operation of the Kaldo furnace is the formation of accretions and blockage of the injection lance due to splashing. This typically occurs during the processing of anodic slimes for the production of doré. In this work, a 1:7 scale model of the Kaldo furnace currently in operation at Metalúrgica de Cobre, Mexico, was built in transparent acrylic plastic. Water and colored oil were used to represent the doré and slag, respectively. The model was used to determine the maximum penetration distance of the injection lance under a variety of experimental conditions at room temperature. Input variables included two types of oil, rotation speed, inclination angle, and the fraction of the vessel volume occupied by the liquids (φ). A mathematical correlation for the dimensionless maximum penetration distance of the injection lance d ∗ as a function of φ, the Froude number of the liquids in the vessel (Fr), the Reynolds number of the gas jet (Re), and the oil-to-water kinematic viscosity ratio (η)was developed. Reasonable agreement between the calculated and experimental values was obtained. Digital images showed that splashing was caused by the turbulent gas jet impinging upon the free surface of the liquids, whereas the cascade effect was negligible. The results of this work have been useful to improve the operation of an industrial Kaldo reactor.

By Malcolm Ross

The Reserve Mining Co., in the processing of taconite iron ore quarried from the Peter Mitchell Pit, deposited the finely crushed waste rock into Lake Superior near Silver Bay Minnesota. In the early 1970s The U.S. Environmental Protection agency filed a lawsuit against Reserve Mining Co., asking the court to force the company to stop dumping into the lake. On April 20, 1974, after a lengthy court battle, the U.S. District Court concluded that the Reserve Mining discharge into Lake Superior violated federal and state pollution laws and thus ordered Reserve Mining Co., to halt the lake disposal of taconite tailings. At the time many feared that some of the mineral particles contained in the tailings (alleged to be asbestos or asbestos-like) would cause human health problems. This Conference was thus convened to readdress the problem of the mineral content of the Biwabik Iron Formation and to whether any minerals contained in the ore could cause human disease. The four papers given in this session address the nature of the mineral particles in the taconite rock, the definition of the term ??asbestos?? and the history of the legal controversy over the possible health effects of certain mineral particles contained in the Biwabik iron range ores. Paper 1?Geology of the Biwabik Iron Formation and Duluth Complex Mark A. Jirsa, James D. Miller, Jr., G.B. Morey The Biwabik Iron Formation was a principal source of ore for the American steel industry during the 20th Century. The unaltered iron deposits, called taconite, contain approximately 30% iron and 50% SiO2. About 75% of the iron in taconite resides in the mineral magnetite, the remainder is largely in iron carbonate and several iron-silicate minerals.

Jan 1, 2007

By Val E. Payne

Issues between resource utilization and resource preservation often develop in connection with coal mining. One such conflict exists in eastern Utah where PacifiCorp and Energy West Mining Company are working with State and Federal agencies to address the resource recovery/resource preservation dispute. The effects of underground longwall coal mining on golden eagle (Aquila chrysaetos) cliff nesting sites have been studied at the Cottonwood Mine since 1986. Subsidence, escarpment spalling, and the nesting activities of the local eagle population were monitored.

Jan 1, 1986

By Brooke T. Mossman

Asbestos fibers are highly fibrous silicate fibers that are distinguished by having a large aspect (length to diameter) ratio and are crystallized in an asbestiform habit that causes them to separate into very thin fibers or fibrils. These fibers are distinct from nonasbestiform cleavage fragments and may appear as thick, short fibers which break along cleavage planes without the high strength and flexibility of asbestiform fibers. Since cleavage fragments of respirable dimensions have generally proven nonpathogenic in animal studies, little data exists on assessing well-characterized preparations of cleavage fragments in in vitro models. The available studies show that cleavage fragments are less bioreactive and cytotoxic than asbestiform fibers. © 2007 Elsevier Inc. All rights reserved. Keywords: Asbestiform; Cleavage; Fibers; Fibrous

Jan 1, 2007

By Wen Tao Liu, Tong Tian, Fu Sheng Niu, Xiu Man Liang

In order to address the difficulty of accurate segmentation of froth images of different sizes, a method of froth image segmentation based on highlight correction and parameter adaptation is proposed. First, a machine vision system on a single-cell flotation machine is built to collect froth images. Homomorphic filtering is used to improve the uneven brightness and shadow of the images. Fuzzy c-means (FCM) clustering is then utilized to classify similar highlights that belong to the same froth. After Otsu threshold segmentation, a parameter-adaptive morphological operation is used to extract the marker points and edge bands and correct the froth edges in the original image. Finally, the modified image is filtered by morphological reconstruction, and the highlight mark is used as the local minimum point for watershed segmentation. Three sizes of froth images are segmented in comparative experiments. The results show that the proposed method is suitable for the segmentation of froth images of different sizes. The position of the extracted segmentation line is close to reality, with average over-segmentation and under-segmentation rates for froth images of 2.6% and 6.8%, respectively. The froth image segmentation performance is stronger than that of the other methods examined.

By G. Deissman, S. Kistinger

For the last 15 years environmental Life-Cycle Assessments (LCA) have increasingly been used to evaluate the environmental performance of industrial processes and products and have been employed as a basis in decision making processes in the public and industrial sector. However, assessment methodologies for environmental protection measures and reclamation/remediation measures with respect to their consumption of natural resources are generally poorly developed. In this presentation a methodology for LCA of environmental protection measures and remedial actions, respectively is suggested, using the remediation/reclamation of mining sites as an example. Key aspect of this approach is the development of an evaluation method appropriate for environmental protection measures, which links the various impact indicators recognised in the impact assessments and allows their integrated assessment.

Jan 1, 2005

By İbrahim Çınar, Hakan Özşen

Mine workers in heavy and dangerous work are under several physical risk factors, for example temperature, humidity, noise, vibration, lighting and air velocity. Thermal comfort includes parameters such as air temperature, air humidity, air flow rate, radiant heat, metabolic rate and garment insulation. In this study, thermal comfort conditions were evaluated using thermal comfort indices defined as predicted mean vote (PMV) and predicted percentage dissatisfied (PPD) which were determined by measurements taken from an underground coal mine for approximately 100 days. Although the metabolic rate (light work) was kept at 2 met, it was found that predicted mean vote ranged between − 2.58 and 1.68. The predicted percentage dissatisfied index was found to reach 95%. According to the results, it can be seen that thermal comfort may have negative effects on occupational health and safety. The change in thermal comfort index values in the Soma Underground Coal Mine was investigated in detail and the reasons for the changes were determined. Furthermore, determining the optimal working environment for the mine workers was also an aim of this study.

By Stephen Phillips, Luigi P. Gonano

Vertical circular shafts have been proposed for multiple access to high level nuclear waste deep geologic repositories. Shaft construction is a critical path item in the commissioning of a repository. Other constraints on the shaft design and construction criteria include the lack of design precedence for long term performance and the importance of minimizing rock and groundwater disturbance. A comparative evaluation of conventional and mechanized shaft sinking techniques is presented in the context of the particular geologic and design constraints. Technical and non-technical factors for blind drilling, blind boring, raise-reaming, drill-and-blast and ream-and slash methods are reviewed for typically "hard rock" and "salt" type repository sites. Appropriate shaft designs are developed, the suitability of each method to the particular requirements evaluated and construction costs and schedules determined. The explicit appraisal of the significant design factors for each method serves as a rational basis for the preliminary selection of the most suitable sinking technique for a particular set of site/design conditions.

Jan 1, 1983

By E. Sun

Tailings disposal is a significant consideration for the mining industry, with the majority of the ore processed in most mining operations ending up as tailings. Several tailings dam failure accidents have occurred during the past few years and mine tailings dam failures are occurring at relatively high rates. Tailings dam failure is disastrous with the serious damage and the loss of lives. To increase the tailings dam safety, a tailings dam monitoring and pre-alarm system (TDMPAS) based on the internet of things and cloud computing platform has been accomplished with the abilities of real-time monitoring of the saturated line, impounded water level, rain fall and the dam deformations etc. The TDMPAS has been applied in several mines in China and helped the mine engineers monitor the tailings dam safety and get warning information automatically and remotely in any kind of weather conditions. This work has been demonstrated the tailings dam monitoring and pre-alarm system (TDMPAS) is meaningful to monitor the tailings dam physical safety condition. The TDMPAS could be applied to monitor all the national tailings dams online in the future.

Jan 1, 2012

By Guowen Dong, Qiyong Li, Qiang Li, Tiejun Chen, Zhihong Wu, Junying Wan

In order to search for a more economical and effective roasting additive for extracting vanadium from stone coal and solve the question of the disposal of PVC waste, PVC waste was proposed as a novel roasting additive to enhance extraction of vanadium from stone coal and realize the comprehensive utilization of resources. By adding this roasting additive, the leaching rate of vanadium reached 94.5% under the conditions that the PVC waste addition was 10 wt%, the roasting temperature was 800 °C, the roasting time was 1 h, the sulfuric acid concentration was 15 vol%, the liquid-to-solid ratio was 1.5 cm3 /g, the leaching temperature was 95 °C, and leaching time was 4 h, which increased by 8.4% compared with that of blank roasting. The thermodynamics calculation showed that the decomposition reaction of mica was performed easier with the participation of HCl produced by pyrolysis of PVC. Meanwhile, The SEM-EDS and aperture test analyses demonstrated that more cracks and voids appeared in the roasted sample by roasting with PVC waste, which could facilitate the release and extraction of vanadium. Additionally, the TG-DSC analyses indicated that PVC could provide large amounts of heat for the roasting process to promote the decarbonization and roasting efficiency of stone coal because of its high calorific value.

By Guowen Dong, Qiyong Li, Qiang Li, Tiejun Chen, Zhihong Wu, Junying Wan

In order to search for a more economical and effective roasting additive for extracting vanadium from stone coal and solve the question of the disposal of PVC waste, PVC waste was proposed as a novel roasting additive to enhance extraction of vanadium from stone coal and realize the comprehensive utilization of resources. By adding this roasting additive, the leaching rate of vanadium reached 94.5% under the conditions that the PVC waste addition was 10 wt%, the roasting temperature was 800 °C, the roasting time was 1 h, the sulfuric acid concentration was 15 vol%, the liquid-to-solid ratio was 1.5 cm3 /g, the leaching temperature was 95 °C, and leaching time was 4 h, which increased by 8.4% compared with that of blank roasting. The thermodynamics calculation showed that the decomposition reaction of mica was performed easier with the participation of HCl produced by pyrolysis of PVC. Meanwhile, The SEM-EDS and aperture test analyses demonstrated that more cracks and voids appeared in the roasted sample by roasting with PVC waste, which could facilitate the release and extraction of vanadium. Additionally, the TG-DSC analyses indicated that PVC could provide large amounts of heat for the roasting process to promote the decarbonization and roasting efficiency of stone coal because of its high calorific value.

By Geoffrey Berry

Exposure?response relationships between the relative risk of lung cancer and quantitative measures of exposure to asbestos are available from a number of epidemiological studies. Meta-analyses of these relationships have been published by Lash et al. (1997) [Lash, T.L., Crouch, E.A.C., Green, L.C., 1997. A meta-analysis of the relation between cumulative exposure to asbestos and relative risk of lung cancer. Occup. Environ. Med. 54, 254?263] and Hodgson and Darnton (2000) [Hodgson, J.T., Darnton, A., 2000. The quantitative risks of mesothelioma and lung cancer in relation to asbestos exposure. Ann. Occup. Hyg. 44, 565?601]. In this paper, the risks derived in these meta-analyses have been compared. Lash et al., concentrated on process and found that the risk of lung cancer increased as the asbestos is refined by processing. Hodgson and Darnton concentrated on fibre type and found that the risk was highest for exposure to amphibole asbestos (crocidolite and amosite), lowest for chrysotile and intermediate for mixed exposure. Some of the differences between the conclusions from the two meta-analyses are a consequence of the choice of studies included. The range of asbestos types included in the studies in the analysis of Hodgson and Darnton was wider than that in Lash et al., enabling differences between fibre types to be analyzed more readily. There are situations where occupational exposure to chrysotile asbestos has shown no detectable increase in risk of lung cancer. Taconite miners have shown no increased risk of mortality due to lung cancer. © 2007 Elsevier Inc. All rights reserved. Keywords: Mesothelioma; Amosite; Grunerite; Taconite; Crocidolite; Tremolite; Anthophyllite; Winchite; Risk assessment; Etiology

Jan 1, 2007

By Graham W. Gibbs

The current state of knowledge concerning mesothelioma risk estimates is reviewed. Estimates of the risk of mesothelioma exist for the commercial asbestos fiber types chrysotile, amosite and crocidolite. Data also exist on which to assess risks for winchite (sodic tremolite) and anthophyllite asbestos. Uncertainty in estimates is primarily related to limitations in measurements of exposure. Differences in the dimensions of the various fiber types and of the same fiber types at different stages of processing add a further complication. Nevertheless, in practical terms, crocidolite presents the highest asbestos related mesothelioma risk. The risk associated with sodic tremolite (winchite) appears to be similar. In chrysotile miners and millers, the mesothelioma risk has been linked with exposure to asbestiform tremolite. Exposure to chrysotile in a pure form seems likely to present a very low if any risk of mesothelioma. While the majority of mesothelial tumors result from exposure to the asbestos minerals, there are other well established and suspected etiological agents. While a practical threshold seems to exist for exposure to chrysotile, it is unlikely to exist for the amphibole asbestos minerals, especially for crocidolite. To date there is no indication of an increased risk of mesothelioma resulting from non-commercial fiber exposure in the taconite industry. © 2007 Elsevier Inc. All rights reserved. Keywords: Mesothelioma; Amosite; Grunerite; Taconite; Crocidolite; Tremolite; Anthophyllite; Winchite; Risk estimation; Etiology

Jan 1, 2007