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By H. Kinilakodi

The authors previously developed a methodology that combines injury and citation measures into an overall mine safety performance evaluation tool, called the safe performance index (SPI). It can be easily adopted by mine operators to monitor trends in their injury and citation experiences as a risk assessment method. In this paper, six normalized safety measures and the SPI are used to evaluate the health and safety risk that existed at mines in the two years preceding the occurrence of a fatality. The percentage of mines is given for which the risk was high or where trends of some of the safety measures indicated moderate risk. In 50% of the mines, this mine safety performance tracking method could have been helpful to the companies, state agency or the U.S. Mine Safety and Health Administration (MSHA) in recognizing and addressing emerging problems with actions that may have been able to predict high-risk conditions, the fatality and/or other serious injuries. The approach would have given extra scrutiny to the risk for mines that encompassed 74% of the fatalities during 2007-2010.

Jan 1, 2012

By John G. Groppo, James C. Hower, Cortland F. Eble, Rick Q. Honaker, Alireza Valian, Stephen F. Greb

Coal and coal combustion byproducts are potential candidates for alternative resources of REEs (rare earth elements). The Illinois Basin is a major coal-producing district in the USA, but little work is available on speciation of REEs in the basin’s coals. In this study, a total number of 382 samples from known locations in the Illinois Basin coal beds were acquired, analyzed for their REE contents, and investigated for any spatial trends or chemical correlations. This study includes Springfield, Herrin, and Baker coal beds—the most heavily mined coals in the basin. An average coal ash from the basin contains 320 ppm REE, with Baker being the highest (407 ppm on average). However, the distribution of REEs in the coal beds was laterally and vertically heterogeneous. A number of trends were found in the REE variations. The most important trend was the relationships of the REE concentrations and fractionations with the distance from the syndepositional sandstones. The total REE concentrations were higher in the proximity of the sandstones, likely due to the increased deposition of detrital material. This increase was the most significant in Springfield coal (90%) and least in Baker (6%). Those coal samples from the Springfield and Herrin coal beds distal from the syndepositional sandstones had a heavy to light REE ratio (H/L ratio) of 0.40 on average, whereas in proximal locations, the ratio was dropped to an average of 0.30. This trend was not significant in the Baker coal bed. In general, higher mineral matter in the coals was associated with higher REEs. In coal preparation plants, refuse rocks can have up to 360 ppmREE. However, the ashes of the cleanest coals had higher REE levels. Such ashes also have a higher ratio of heavy to light REEs. The highest REE concentrations were found in the claystones and the shales associated with the coal beds. Since the naturally occurring calcite, quartz, and pyrite samples were depleted in REEs, an association of REEs with the clay minerals can be suggested.

Jul 20, 2020

By Konrad J. Banaszak

At least for the time being, these seems to be general but not universal agreement that Mississippi Valley type ore deposits formed entirely or in major proportion from heated connate brines (e.g. 1) Even with that agreement, major questions remain. I will present a coherent geochemical model and look at alternative views in the context of that model. The pattern of the following discussion is 1) the general geochemistry of the ore fluid, 2) the density-temperature relations and possible mechanisms of flow of those fluids, 3) the mechanisms of transportation and deposition of the ore minerals, and 4) a summary of a coherent model of genesis. The data equivocally define much about the deposits. The answer is still elusive.

Jan 1, 1979

By Lauren W. Choate

Wollastonite, a calcium metasilicate, derives its name from the man who discovered the mineral, Doctor William H. Wollaston, an English scientist. OCCURENCE Occurences of the mineral have been noted in Finland, Switzerland, Russia, Japan, Mexico and in the United States in Texas, California, Arizona, and New York. The only commercial deposit now being exploited is at Willsboro, New York. It is mined and processed by the Cabot Corporation whose home offices are in Boston, Massachusetts.

Jan 1, 1964

By J. A. Ober

"In 2016, the estimated value of total nonfuel mineral production in the United States was $74.6 billion, a slight increase from the revised total of $73.4 billion in 2015 (Table 1). Increased construction activity spurred increased production of industrial minerals, especially those used in infrastructure and residential construction. Although starting the year relatively low, prices for several metals, especially for some of the precious metals, began to trend upward. Decreased production of most metals produced in the United States, however, contributed to an overall decline in the value of metal production.Several U.S. metal mines and processing facilities were idled or closed permanently in 2016, including iron ore mines in Michigan and Minnesota; three primary aluminum smelters in Indiana, Missouri and Washington; one secondary zinc smelter in North Carolina; a titanium sponge facility in Utah and titanium mineral operations in Virginia. In addition, in May, the weekly average rig count for oil and gas drilling reached its lowest level since the 1940s when that measurement was first recorded. The reduced drilling activity resulted in decreased production of some industrial mineral products used in the drilling sector. Trends in mineral-related sectors of the domestic economy declined or held steady, except in the manufacturing of nonmetallic mineral products and nonferrous metals excluding aluminum, which increased. Overall, mining trended downward as the result of significant declines in coal mining, oil and gas extraction and metal mining (Table 2). Discussion of mine production is frequently segmented according to the type of materials produced within the broad categories of metals and industrial minerals (also known as nonmetallic minerals). Industrial minerals can be further subdivided as construction aggregates and other industrial minerals. Metals tend to have higher unit values but very low production quantities compared with those of industrial minerals, which have higher production quantities but are lower-valued materials, such as crushed stone or construction sand and gravel. Therefore, for discussion and analysis of the performance of the nonfuel minerals industry, the value of production is used rather than the tonnage produced. Tonnages of construction aggregates are orders of magnitude larger than those for most other mineral commodities thus making direct compar"

Jan 5, 2017

By Yushuai Xian, Youjun Tao, Fangyuan Ma

This study compared particle size distribution and density distribution of crushed products for waste printed circuit boards (WPCBs) before and after heat treatment. The crushing process for heat-treated WPCBs is a selective crushing process; more metal is concentrated in the coarse particle range of 1.0–0.5 mm and high density range of 2.8–2.96 g/cm3. WPCBs were separated using the Falcon separator to recycle useful metals. The Box-Behnken module of Design-Expert was used to obtain optimal separation parameters, namely, rotational frequency of 25 Hz, recoil water pressure of 0.025 Mpa and feed speed of 34 ml/s. On this basis, the separation indexes for WPCBs with and without heat treatment were compared. Experimental results show that the recovery effect is better for heat-treatedWPCBs than for thosewithout heat treatment. Comparedwith the non-heattreatedWPCBs, the product grade of heat-treated WPCBs is 1.95% higher, and its recovery is improved by about 14%. Finally, characteristics ofWPCBs before and after heat treatment were analyzed on the basis of stress experiments and scanning electron microscopy (SEM), respectively. Results of mechanical characterization indicate that the stress experiment for non-heat-treated WPCBs has a maximumpressure load of 212 N and displacement of 20mm, but heat-treatedWPCBs only need 140 N stress and 14 mm displacement. SEM shows that copper foil and fiberglass cloth are deformed in different directions and sizes after heat treatment to form gaps, which promote liberation of copper foil and fiberglass cloth.

Sep 10, 2020

By R. A. Thomas, C. D. Litton

"The objective of this study was to develop a laboratory-scale method to rank the ignition and fire hazards of commonly used underground mine materials and to eliminate the need for the expensive large-scale tests that are currently being used. A radiant-panel apparatus was used to determine the materials’ relevant thermal characteristics: time to ignition, critical heat flux for ignition, heat of gasification, and mass-loss rate. Three thermal parameters, TRP, TP1 and TP4, were derived from the data, then developed and subsequently used to rank the combined ignition and fire hazards of the combustible materials from low hazard to high hazard. The results compared favorably with the thermal and ignition hazards of similar materials reported in the literature and support this approach as a simpler one for quantifying these combustible hazards. Resumen ¦ El objetivo de este estudio fue el desarrollo de un método a escala de laboratorio con el fin de clasificar los peligros de ignición y fuego de materiales comúnmente usados en minería subterránea y la eliminación las pruebas costosas y a gran escala que se realizan actualmente. Se usó un aparato de panel radiante con el fin de determinar las características térmicas relevantes de los materiales: tiempo de ignición, flujo de calor crítico para ignición, calor de gasificación y tasa de pérdida de masa. Se derivaron tres parámetros térmicos de los datos: TRP, TP1 y TP4, luego fueron desarrollados y subsecuentemente usados para clasificar los peligros combinados de ignición y fuego de materiales combustibles, de bajo riesgo a alto riesgo. Los resultados tuvieron una comparación favorable con los riesgo/peligro térmicos y de ignición de materiales similares reportados en la literatura y apoyan este enfoque como uno más simple para la cuantificación de estos riesgos combustibles"

Jan 1, 2015

By John Newby, Ulf Gwildis, Fred Marquis

From the Brightwater Conveyance System in Seattle to the Second Narrows Water Supply Tunnel in Vancouver, BC, the design and construction of deep-lying tunnels in the Pacific Northwest often require the incorporation of deep portal shafts. Alluvium overlying marine and glacial deposits combined with the high regional seismicity is the common geologic setting. The latest example illustrating the development of shaft design for this scenario is the 40-m-deep shafts of the Annacis Island Wastewater Treatment Plant New Outfall System. The main components of the shafts include the initial lining, providing the excavation support system to be used for launching and receiving a 5-m-diameter TBM; and the final lining, designed to withstand all static and seismic loads and to remain viable for the intended design life. This paper presents design and construction considerations for these shafts against the background of and lessons learned from past project experiences.

Jun 13, 2021

By Qingwen Shi, Gang Xu, Shuwen Wang, Brijes Mishra

Pressure relief borehole is one of the most effective methods to treat coal burst in deep-buried coal seams. However, due to the large amount of randomly distributed fractures in the coal body and the varying stress environments in underground coal mines, there is no practical method to assess relief boreholes by far, which brings problems for borehole design and construction. This study focuses on the assessment of relief boreholes in a single driving entry wherein the impact of mining panels on relief boreholes is eliminated. A practical method, focusing on field monitoring of borehole deformation with a new device, is developed to evaluate the single driving entry’s relief boreholes. This method is applied to a Chinese coal mine. The application results showed that the convergence process of the boreholes showed a three-phase characteristic. Phase one involves the fastest deformation, reaching up to 8% in the first 3 to 4 days. Phase two lasts longer and converges more, reaching up to 30% in 4 months. Phase three stays balanced until the excavating face moves. The three-phase characteristic indicates that a large diameter of the borehole ensures relief efficiency because the borehole provides adequate space for deformation throughout its life span. In addition, it is verified that long boreholes and slow footage improve relief efficiency by providing adequate time for the boreholes to work. The application proposes that boreholes in the test coal mine need to be drilled larger and longer for optimization.

Oct 19, 2021

By Richard A. Grieve

A 63.5 metric tons per hour (70 TPH) demonstration coal preparation plant was constructed on the Iowa State University campus, Ames, Iowa, as a part of the Iowa Coal Project funded by the state of Iowa and administered through the Energy and Minerals Resources Re-search Institute. Processing equipment in the plant circuit includes a heavy media separator, concentration tables, separating and dewatering screens, and conveying equipment. Coal samples of size 907 metric tons (1000 tons) with sulfur contents ranging from 2.5 to 8.75% sulfur from seven mines in the state of Iowa have been pro-cessed in the plant. Sulfur reductions have averaged 35%. With ash reduction averaging 45%. Equipment for advanced fine coal beneficiation research is currently being installed in the plant to include a slurry pretreatment circuit, froth flotation, oil agglomeration, pelletization, hydrocyclones, advanced design thickener and disc filtration.

Jan 1, 1978

By C. D. Harrison, J. W. Parkinson

This paper compares the ash slagging potential of Illinois No. 6 seam coal as raw coal, as commercially cleaned coal processed in a baum-jig plant, and as coal cleaned to a reduced ash specification at the Electric Power Research Institute's (EPRI) Coal Cleaning Test Facility. The comparison is based on ASTM ash fusibility data, a slagging index, gravity fractionation analyses of critical mineral matter compounds, and comparative pilot combustion tests. The first three grounds of comparison are laboratory data. The final comparison involves burning about 13.6 t (15 st) of each coal at Conoco's 4.40-kW/h (1.5 million-Btu per hr) test combustor. The evidence of these four comparisons indicates that lowering the ash specification of coal before combustion can significantly improve the ash slagging characteristics of Illinois No. 6 seam coal.

Jan 1, 1987

By M. Ramokhothoane, S. Rupprecht

"NTRODUCTION Women employment in the mining industry dates back to the 19th century. Various parts of the world, for example, India, Japan, the United Kingdom and the United States of America had women employed in large numbers. The women’s jobs were primarily manual in nature. Women were used to carry coal in buckets from the coal face and out the mine, and those who worked on the surface plants were used to sort waste rock from the coal product. Other heavy industries, which were traditionally male dominated, for example the military, also had a considerable number of women supporting the war effort. The outbreak of war also caused a shortage of labour, which in turn, necessitated that women were used in various roles during the war. After World War II, women returned to their traditional roles, but had acquired new skills, and had a different outlook to life. The wearing of pants and short hair became fashionable, as a result of being in the army.Various laws were passed which prevented the employment of women underground. Different countries had rules that they believed were in the best interest of women and were of the opinion that the rules somehow were protecting women against the harsh working conditions. In South Africa, post 1994, there has been a shift in thinking in regard to the employment of women in the mines. WOMEN IN SOUTH AFRICA MINING In the words of the Minister of Women in the Presidency, Minister Susan Shabangu, “women must take centre [sic] stage as the country gears itself for the implementation of radical socio-economic transformation policies and programmes in the next five years” (SA Government News Agency, 2014). In as much as some progress has been made in advancing women, more needs to be done in order to realize sustainable benefits in the economy. The emancipation of women is a reality and remains top of the South African government agenda. From the Authors’ experience there are two types of men in the mines. The first group support change and see the value in it. To them, women in mining bring in the diversity and play the complementary role in achieving greatness. There is no fear of job security and humiliation but a great sense of “camaraderie”. The other group continues to enforce stereotypes, which works against the spirit of redressing the imbalances of the past."

Jan 1, 2018

By LeRoy D. Loy

Would you believe me if I told you the constant battle between Government regulatory agencies and industry could be won by both sides? No, I'm not crazy, nor have I been soaking up any of that fine Kentucky whitelightning. But I have recently been a participant in a battle where both sides won. Actually, I'm using the term "battle" loosely because, in reality, it wasn't a battle at all - despite the fact that all the ingredients were there for a monumental struggle; i.e.. government, industry, special interest groups and a controversial issue - the development of effluent limitations. I'd like to tell you about it. Historically, on one side of the battle, government has always been ac¬cused of adopting regulations with limited evaluation of existing technologies; and then with seemingly no regard for the economic consequences. On the other side, industry gets punished by government's harsh actions because of their past "do-nothing" attitude toward pollution control. Recently, this battle seems to be losing steam, because both government and industry are beginning to realize that, ultimately, they both will lose. Even more important is the fact that both sides are, or should be, working for industrial expansion compatible with environmental protection.

Jan 1, 1977

By K. M. Kim

An analysis was conducted to determine the effects of blasting on slope stability and downstream comminution processes. To investigate these effects, the extent of blast-induced rock damage and the magnitude of induced stress were examined. This analysis showed that damage may extend up to 500 m (1 MPa, tensile strength) into the rock mass, a distance that is sufficient to have an impact on the pitscale slope over the long term. In addition, the damage zone was calculated using the assumption that compressive waves are the primary agent in microfracturing during blast fragmentation. The calculated damage zone — up to 2.2 m (43 MPa, rock mass compressive strength) — indicates that microfracturing can occur throughout 20-50% of the entire rock mass in the blasting area, depending on the blast geometry, burden and spacing. Finally, an economic analysis was conducted by comparing two assumed blasts in a copper mine. The change in energy required for crushing and grinding was demonstrated using Bond’s law after increasing the blast energy from 180 kcal/t to 350 kcal/t. A total cost saving of 13.3% ($9.4M) was achieved with the increase. However, the benefits of blast-induced microfracturing must be balanced against the potential impacts to slope stability to ensure safe conditions, a top priority in mining operations.

Jan 1, 2014

By S. Que

Local community acceptance is a key aspect of planning and managing mining projects, whether through sustainability assessment and reporting or corporate social responsibility programs. However, there has been very little research to understand the determinants of community acceptance. This paper seeks to identify key mine characteristics and demographic factors that influence individual acceptance of mining projects. Six demographic factors and 16 mine characteristics were selected based on literature review. Four of the six demographics factors were confirmed to be significantly (p < 0.05) correlated with people?s attitude of the importance of the mine characteristics. All sixteen mine characteristics are identified as important factors. The most important mining factors are Job opportunities, water shortage or pollution, air pollution and land pollution. Both the mining and control groups have same opinion of 12 mining characteristics and differ on four (infrastructure improvement, labor shortage for other businesses, noise pollution, and mine life). During design and management of mines, this data can be used as a reference. This result will facilitate better choice experiment (survey) design for discrete choice modeling. Such discrete choice models can provide a viable framework for data-driven community engagement and sustainable mine management.

Feb 23, 2014

By N. A. Karl, D. R. Wilburn

"This summary of international mineral exploration activities for the year 2015 draws upon information from industry sources, published literature, SNL Metals & Mining (SNL) (Charlottesville, VA) database and specialists in the U.S. Geological Survey (USGS) National Minerals Information Center. The summary provides data on exploration budgets by region and mineral commodity, identifies significant mineral discoveries and areas of mineral exploration, discusses government programs affecting the mineral exploration industry, and presents analyses of exploration activities performed by the mineral industry.Three types of information are reported and analyzed in this annual review of international exploration: budgetary statistics expressed in U.S. dollars provided by SNL; regional and site-specific exploration activities that took place in 2015 as compiled by the USGS; and regional events that affected exploration activities including economic, social and political conditions, which were derived from published sources and discussions with USGS and industry specialists. Commodity and regional compilations are presented in this summary. Because multiple sources were used to develop commodity and regional compilations, statistics may vary depending on the source and type of data that are being reported.The SNL data summarize planned company budgets for worldwide exploration activities in 2015 for 24 nonfuel mineral commodities and metal alloys and are based on company surveys. Surveys focused on precious metals (gold, platinum-group metals and silver), base metals, (cobalt, copper, lead, molybdenum, nickel, tin and zinc), bulk commodities (bauxite, chromite, iron ore, manganese, phosphate and potash), and other commodities (diamond, graphite, heavy-mineral sands, lithium, niobium, rareearth elements (REE), tantalum, tungsten and uranium).USGS data compilations and analyses are based on information provided by USGS mineral commodity and country specialists, as well as industry contacts and published trade journals. The USGS data summarize exploration site data collected for more than 80 minerals and materials, with a focus on base metals, diamond and precious metals. The USGS analyzed available information to assess the level of exploration activity in 2015 and to report trends in mineral exploration activity for the period 2005 through 2015. These analyses identify where mineral exploration is occurring by commodity and region and the intensity of activity that is taking place in each region for selected mineral commodities, and determines those factors that most affect changes in exploration activity."

May 1, 2016

By D. R. Hanson, H. Lawson

In this study, NIOSH researchers conducted a machine learning analysis to examine whether a model could be constructed to assess the probability of dynamic failure occurrence based on geochemical and petrographic data. Random forest, cluster analysis and dimension reduction were all applied. The objective of dimensionality reduction was to explore patterns and groupings in the data and search for relations between compositional parameters. Cluster analyses were performed to determine if an algorithm could find clusters with given class memberships and to what extent misclassifications of dynamic failure status occurred. A random forest analysis performed on data from the Pennsylvania Coal Sample Databank cross-referenced with accident data from the Mine Safety and Health Administration (MSHA) determined that 7 parameters of the 18 examined exerted the most influence on results. Cluster analysis on data after dimensionality reduction resulted in a hierarchal clustering algorithm finding four clusters, with one relatively distinct dynamic failure cluster, and three clusters consisting mostly of control group members but with a small number of dynamic failure members.

Feb 1, 2023

By Hemant Agrawal, Arvind Kumar Mishra

Rock breakage using blasting is one of the important operations of the mining industry. The delay timing decides the initiation sequence of holes in the blasts and is a crucial factor to improve the overall blast performance. Blast-induced ground vibration is an undesired yet unavoidable outcome of blasting. Peak particle velocity (PPV) is commonly used to measure the magnitude of blast-induced ground vibration. Channelization and better utilization of explosive energy delay are provided between blast holes using initiating systems. The use of different initiation systems even on the same site results in a very significant difference in the values of PPV generated. Due to scattered delay timings of pyrotechnic detonators, the scaled distance predictor equations obtained become unreliable. The error/scatter in delay timing leads to overlapping of holes and hence increases in maximum charge per delay. In this paper, an analytical approach has been discussed to measure the overlapping of holes during blasting with initiation systems having inherent cap scatter. The analytical approach will be calculating the probable overlapping of holes due to scatter in delay timing and will help blasting engineers to understand the variation in maximum charge per delay due to pyrotechnic based initiating systems. In this study, a total number of 102 blasts were conducted using different initiation systems at two different opencast coal mine and 221 corresponding blast vibrations events were recorded.

Nov 10, 2020

By H. Mischo, R. Ellmies

Uranium has been mined in Namibia since the 1970s. The worldwide increasing need for energy in the early 2000s has led to the development and opening of a second uranium mine in 2007 and has triggered an increased interest in uranium exploration, often referred to as “the Namibian Uranium Rush.” In all, four mining licenses have been granted by the Namibian Government, which currently has two mines in operation, a third undertaking trial mining and the fourth in project finance negotiations. In addition, highly intensive prospecting activities at additional deposits are at an advanced stage. The finalization of the strategic environmental impact assessment (SEA) on uranium mining in 2010, the first of its kind and scale in the world, has enabled the Namibian government to assess this uranium rush and its tremendous legal, socioeconomic and environmental impacts and to prepare for the different future scenarios conceivable when this article was written in 2011, including both a skyrocketing and a complete breakdown of demand scenario. The Fukushima disaster and plans of the Namibian government to significantly increase royalties and company taxes in 2011 have threatened the market situation, forcing investors to reevaluate Namibian uranium mining projects. However, with the tax and royalty increase initiative since withdrawn, most projects are back on track at this point in time.

Jan 1, 2012

By C. V. Deutsch, D. A. Silva

The geologic modeling of multiple domains is required for the prediction of mineral resources and reserves. In general, explicit methods have wide acceptance among modelers due to the ability to manually add deemed important trends and geological features into the models. As an alternative, implicit geologic modeling techniques are increasingly adopted to reduce professional time requirements. These methods aim for objective, repeatable and flexible models by replacing the manual time-consuming interpretation of sections with the interpolation of signed distance values. These techniques, however, have been developed for the binary case of two domains at a time. The current paper presents an algorithm that extends the binary case to multiple domains. The method is able to transfer large-scale geological features from data to geologic models. A case study illustrates the benefits of the algorithm and practical implementation considerations.

Jan 1, 2016