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By S. Todd Mickleborough

The geostatistical technique of conditional simulation is applied to measure the uncertainty in factor of safety predictions for soil slopes where there is incomplete knowledge of the spatial distribution of soil properties. A case study considers a natural clay slope in Canada. The sequential indicator simulation technique is used as a means for generating a series of spatial maps of soil properties for this site. These maps approximate random draws from the conditional probability density function that characterizes existing uncertainty in the spatial distribution. Factor of safety determinations are then made for each simulated map using the simplified-Janbu approach, where the computations are performed with a new computer program that can operate on irregular spatial profiles of soil properties specified on a discrete grid. A unique capability of this approach is the ability to generate the distribution of factor of safety conditional to the type, position, and value of existing site characterization measurements. This capability should reduce uncertainty in FS predictions.

Jan 1, 1993

By David Mast, Irwan Halim, Seung Han Kim

Nowadays more infrastructure tunnel projects are procured using design-build method. In this environment, the Owner’s engineer would typically provide performance requirements for the design-builder, and the Contractor’s designer would work with the contractor to design the tunnel lining based on the Contractor’s means and methods and manufacturing process. This paper will describe the typical requirements provided by the Owner based on its design objectives, and the means and methods by the Contractor that would significantly impact the design. Project examples and recommendations for Owner’s requirements will be provided that can optimize the design and still achieve the Owner’s performance objectives.

Jun 13, 2021

By Edward Hall Smith

The E1 Indio Mine is located in the Andes mountains about 180 kilometers East of La Serena, capital of the Fourth Region of Chile. It is reached by an international highway running up the Elqui Valley as far as Juntas from where the last 42 kilometers is on a road constructed by the Company. The plant is located at 3.900 meters above sea level among extremely rugged terrain with nearby mountains rising about 5.500 meters. Climatic conditions at these altitudes are severe with winter temperatures down to -20°C. Snow storms lasting several days and leaving up to two meters of snow have been experienced, while fierce winds are corm=.

Jan 1, 1984

By Yun-tao Xin, Yu Yi, Kang Yan, Gang Li, Xiao-dong Lv

This study investigated the selective removal of arsenic from high-arsenic dust in alkaline systems and the effects of different leaching conditions. The results indicated that the liquid–solid ratio, NaOH concentration, and sulfur dosage had a significant influence on the process. The leaching efficiency of arsenic reached 99.57%, while that of lead was as low as 0.03% under appropriate conditions. In particular, the addition of sulfur can effectively promote the leaching of arsenic and reduce the dissolution of lead in the solutions. An artificial neural network was used to model the leaching process. It consisted of a back-propagation artificial neural network model with a “6–10–2” structure that could effectively simulate and predict the value with more than 99% accuracy. Based on the difference in weights of the different parameters in the neural network model, the relative importance of the parameters related to arsenic and lead leaching efficiency was obtained, which followed the order of NaOH concentration, liquid–solid ratio, sulfur dosage, temperature, time, and stirring speed.

Jul 29, 2021

By Andrew Stafford, Kate Willa Brown Requist, Eric Lutz, Simon Lotero Lopez, Moe Momayez, Jeffrey Gordon

This formal literature review identifies strengths and shortcomings of current literature related to mine rescue, self-rescue, and self-escape technology. Key concepts and factors that influence the decision making behind mine rescue and self-escape were identified. Historically, underground mining has been one of the most dangerous occupations due to the harsh nature of working environments. During the latter half of the twentieth century, and into the twenty-first century, mining fatalities have declined, yet large-scale mine emergencies persist. The emergence of new technologies, in combination with evidencebased mine emergency research, is resulting in new training methods, monitoring systems, and self-escape approaches being tried in operating mines. This review identifies areas in which substantial research is being conducted, such as the use of virtual reality and game-based training and areas that warrant further development such as the measurement and information gathering capabilities of unmanned ground and aerial vehicles, as well as emergency management and incident command systems. This paper summarizes the current underground mine rescue and self-escape landscape in the USA, including the breadth and depth of mine rescue and self-escape training and practices as evident in the literature.

Nov 2, 2023

By Jiayao Wang, Jian Chen, Leiting Shen, Hongyang Wang, Zeping Cao, Ziru Wang

Large amounts of by-products, including coal gangue, circulating fluidized bed (CFB) slag, and coal fly ash (CFA), are generated during mining, washing and burning of high alumina coal (HAC). The stockpile of these by-products of HAC will cause the pollution of air, water and soil. Meanwhile, the unbalanced regional distribution of bauxite and alumina production has been a critical challenge for the sustainability of world alumina refineries, especially for China. Therefore, economical extraction of alumina from by-products of HAC not only resolves the environmental pollution problems caused by stockpile but also decreases the dependence degree of import bauxite in China. Considering the fact that powder alumina can only be produced by alkali methods, the alkali extraction of alumina from by-products of HAC is summarized in this paper. Based on the formation process of by-products of HAC, the principle, research status, and problem of existing methods were analyzed and discussed, as well as the forecast of research trend. The analyses indicate that simplex recovery of alumina from byproducts of HAC generates large amounts of leaching residue (red mud) with difficulty for disposing, while comprehensive extraction of alumina and silica meets the research trend for clean and high-value utilization.

Aug 25, 2023

By Chunhui Zhang, Enton Bedini, Jiang Chen, Fengchao Yang, Hang Dong, Xiaoyan Chen

The alteration formed by the reaction of ore-bearing fluid and wall rock is often used as an important prospecting indicator, resulting in the dilution or enrichment of metals or related trace elements. A variety of rock-forming and metallogenic elements have been analyzed in regional stream sediments so that the relationship between the ore-bearing altered rock and the change in the geochemical elemental content can be obtained. Therefore, by using appropriate models, such as matched filtering, the abundance of the distribution of wall rock alteration, similar to the discovered deposits, can be modeled by using the distribution of geochemical elements in the region, and the areas with high distribution abundances are usually favorable prospecting targets. The alteration types related to gold mineralization in the Baiyun gold deposit are potassium feldspar alteration, silicification, pyritization, sericitization, and chloritization. In this paper, the geochemical data of the Qingchengzi ore field (1:200,000 and 1:50,000) have been used to form geochemical images through rasterization. In the three sections of the Baiyun gold deposit, binary-coded curves have been formed, revealing the differences in geochemical elements in stream sediments between altered rocks and the rocks surrounding the Baiyun gold mine. Among them, Au, W, and Mo are enriched elements, while Sn, Zn, and Hg are depleted elements. Several gold deposits are found in the predicted altered rock area by using the matched filtering method during fieldwork, which shows the effectiveness of the method.

Dec 30, 2023

By Dushasan Kundu, B. N. Shivakiran Bhaktha, Khanindra Pathak, Sarbojit Mukherjee

Mine safety and quality of life of miner working in underground mines depend to a large extent on mine illumination and communication. The provisioning of reliable, safe, and cost-effective illumination is critical, particularly in underground gassy coal mines. To prevent firedamp explosion by electrical switching operation in coal mining industry requires implementing intrinsically safe illumination circuit. The luminaire design also needs to be certified and installed properly. The current illumination systems installed inside mines require a lot of energy which is obtained from nonrenewable resources. In this work, the design and implementation of solar-powered optical fiber-based illumination are studied and implemented in the Jhanjra underground coal mine, Eastern Coalfield Limited, and a Li-Fi-based communication system for underground coal mines is proposed. Silicate optical fibers of various core diameters and numerical apertures are characterized for illumination applications and their efficiencies are reported. The possibility of achieving optical fiber-based solar, laser, and hybrid illuminations in underground mines is discussed. The design and fabrication of a Fresnel lens-based solar tracker for solar illumination are also presented. The optical fiber-based illumination system is installed in an underground coal mine and the illumination of over 70 lux is achieved at the work plane. Finally, optical fiber-based illumination and simultaneous basic Li-Fi communication are demonstrated and will be beneficial to the underground coal mining industry.

Apr 14, 2023

By D. M. S. Bhatia

Twenty-six insitu analyses of cubic galena crystals from a Mississippi Valley-type deposit were undertaken with a laser microprobe spectrograph to study the variation of nine trace elements from the crystal center to its periphery, both along the diagonal and vertical. The general trend is an increase in the concentrations of Ag, Ga, Ge, and In with As showing the opposite trend Bi, Cd and Sn did not show any pattern. Sb was not detected. These variation patterns nay serve as a model for similar studies of other Mississippi Valley-type deposits.

Jan 1, 1984

By J. A. Hartlage

Four years ago, Ashland Chemical Company introduced a new copper solvent extraction reagent for hydrometallurgical utilization. The reagent, an alkylated 8-hydroxyquinoline, is called Kelex 100 ®(1). Since the time of introduction, the reagent has been investigated by several workers for its solvent extraction utility in the separation and purification of transition metals (2-7). In the following text, those factors which are essential to the optimum performance of Kelex 100 on concentrated copper solutions will be discussed. To date, the reagent has been found useful in active concentrations of from 1 to 20% Kelex 100. In order to achieve the best performance for Kelex 100, it has been found that a phase modifier is essential. Various alcohols and phenols have been evaluated in order to improve phase performance and stripping characteristics of the solvent system. Modifiers and diluents are especially important when solvent activities between 3 and 20% Kelex 100 are employed. A 15% Kelex 100 solvent, for example, containing 15% nonyl phenol in Escaid 100 (Exxon) can be utilized to remove greater than 33 grams per liter of copper from an aqueous feed without interstage neutralization, and in the same process scheme the reagent can be stripped to less than 1 gram per liter barren organic producing a pregnant electrolyte containing greater than 40 grams per liter copper and less than 120 grams per liter sulphuric acid. The unusually efficient stripping of Kelex is accomplished by protenation of the extractive molecule during the stripping process.

Jan 1, 1974

By Josh B. Taggart

Some twenty to twenty-five years ago we saw the beginning of mechanization in our coal mines, It has now progressed to the point Chat as instruments of production the pick and shovel are things of the past, They had to give way to better and more efficient methods--so mechanization, followed by and combined with automation, has become common-place in our mines. Our coal could not keep its competitive position without this progress Without it our industry could not look to the future with any degress of confidence. Today we lock back and see cases of regained and salvaged markets. We see better coal products being produced at decreasing costs. We see better utilization of manpower and a stronger, more confident industry, Our hats arc off to those mining men, equipment manufacturers, labor leaders, and others who had the foresight to work toward these ends and the ability to bring them about.

Jan 1, 1962

By Robin P. Gardner

The development and use of short-lived radioactive tracer methods for the on-stream determination of residence time distributions in large-scale ball mills is described. Tests are reported on a pilot-plant ball mill with 0.43 m diameter and 0.86 m length and on an industrial mill with 1.83 m diameter and 2.74 m length. Tests with different tracer feed sizes indicate that the residence time distributions on both mills are independent of charge particle size. Similar tests are planned for a-large ball mill of 4.57 m diameter and 9.30 m length. No safety problems were encountered in these tests and none are anticipated in tests of the larger mill.

Jan 1, 1978

By Ruiren Jin

In alkaline pulp, galena is depressed by sodium carboxymethyl cellulose (NaCMC), while Cu(II)-activated sphalerite exhibits a high flotability so that satisfied separation can be achieved. In addition to hydrogen bonding, chemical bonding of NaCMC with galena is confirmed by IR; only hydrogen bonding is involved between NaCMC and Cu(II)-activated sphalerite. It is also found that the greater the degree of substitute and polymerization of NaCMC, the stronger the depressive effect of NaCMC and that lower stirring speed favors the depression.

Jan 1, 1987

By J. Chai, Q. Yuan, B. Qiu

"Overburden strata deformation monitoring is one of the key problems in ground control. Using geophysical method through surface drilling to detect strata deformation is commonly used in the industry. In this paper, a geophysical method based on the distributed optical fiber sensing (DOFS) system were conducted in the laboratory, where a DOFS-based strata deformation monitoring experiment was performed with three physical models. The results show that the DOFS method precisely detects the rock mass deformation and strata structure forming with the Brillouin frequency shifts (BFS) representation. The BFS curves are divided into three phases, which reflects the horizontal three zones developed in the overburden. The BFS distribution presents a multiple stages form, the 1st stage corresponds to the caving zone and the 2nd stage corresponds to the fracture zone. Based on the multiple stages form, the evolution of the water flowing through fractured zone have been determined and the controlling effect of key strata over the water flowing fracture has been pointed out. In the end, the comparison validation proves the accuracy and reliability of this method, and it could be a new approach for the ground control research. INTRODUCTION Overburden rock strata above the work face space will propagate from slight deformation, part destruction to violent movement because of the underground coal mining. It is fundamental and an intrinsic requirement of ground control to monitor the mining-induced rock mass deformation.[1] Overburden strata have their significant mechanical behaviors and movement under damage deformation and fracture. Overburden strata deformation affect the mining ground pressure control directly, and performance in the relationship of supporting equipment and the surrounding rock, the mining-induced fracture distribution and the loss of underground water resource, the ground surface structure stability and the ecological environment.[2] From the perspective of the concept of safe and efficient scientific coal mining: the overburden strata deformation is an important part of mining method selection and reasonable supporting solutions decision which can solve the issues like the roof supporting force calculation, overburden fracture distribution and gas drainage, ground subsidence, separation of coal and rock control and top-coal recovery rate and so on. From the perspective of green and ecological mining: the overburden strata deformation is the key basis of studying the mining-induced ground subsidence and mining area ecological damage, and such engineering problem like environmental protection in mining area, ecological restoration in mining subsided land and the water conservation in fragile ecology area of mining could be solved based on it.[3-6] Therefore, the mining-induced overburden strata deformation is the key of ground control and needs to be controlled artificially."

Jan 1, 2017

By Thomas C. Shrake

The Lomas Bayas copper property is located93 km (58 miles) east of Antofagasta, Region II, Chile (Fig. 1). The deposit was discovered in 1880. The deposit produced intermittently until 1992. Production at Lomas Bayas took place in high-grade veins and breccias mined underground. During 1991, Empresa Minera Mantos Blancos SA (EMMB) optioned the property from Compania Doña Ada SA. Doña Ada maintained the right to continue mining the ores by open-pit and block-caving methods and hauling the ore to its plant located60 km (37 miles) to the north. EMMB conducted exploration and column test programs. On May 9, 1994, Compania Minera Gibraltar Ltda.(CMGL) signed a purchase option agreement to acquire the Lomas Bayas property. CMGL conducted 8,612 m(9,490 ft) of reverse-circulation drilling, 2,028 m (6,650ft) of diamond drilling, a series of metallurgical tests and geologic mapping. The company then decided to exercise its purchase option.

Jan 1, 1996

By John J. Dran

[This paper summarizes the more popular mineral valuation techniques being used by the dining industry, and attempts to demonstrate how they are Interrelated and where some are in error when compared to modern methods of financial analysis. The academic community and the larger and more sophisticated raining companies, have largely rejected the older valuation methods such as the, Hoskold and Morkill concepts and replaced them with "discounted cash flow" (DCF) techniques. The relevancy and usefulness of the older methods have been questioned primarily on the basis of their underlying assumptions that mining companies do not have numerous alternative investments and must use sinking funds deposited at market or ?safe" rates of return to recover the purchase price of mineral reserves. The ability to reinvest In numerous (often non-mining} alternative business ventures, the changing purchasing power of the dollar, corporate income and other taxes, depreciation and depletion allowances, and modern financial management practice, all mitigate against the continued use of the older valuation methods, especially for the larger mining companies. Snail mining companies and Individuals still use these methods largely out of habit and familiarity. This paper attempts to point out the weaknesses and strengths of the valuation methods In current use in the hope that these techniques may be better understood and [rcrn] appropriately applied.]

Jan 1, 1973

By R. L. Grayson

Focusing on relationships between severity measure versus productivity and other factors, this paper presents a comprehensive study of injuries for U.S. underground coal mines in 1996 by mine size. Based on analyses of data, generally the larger the mine, the more productive it is (in tons per employee-hour), but the more severe is its injury experience (r = 0.65). Within very large, large, and medium mine sizes, however, the more productive the mine, the less severe is its injury experience (r =-0.43, -0.36, and -0.26, respectively). For small and very small mines, a more deeply nested analysis is required to understand relationships. Other interesting relationships and comparisons are presented.

Jan 1, 2000

By S. Mendenhall

The Golden Sunlight Mine (GSM) began operation in 1982 with a strong commitment to environmental stewardship and the local community. This commitment ensured the long-term physical, chemical and ecological stability of the mine site and maintained an active partnership with local stakeholders. Concerns for economic development intensified as mine closure loomed on the horizon and fostered the inception of the Community Transition Advisory Committee(CTAC).This coalition of interested area stakeholders has the primary focus to sustain current mining operations while concurrently seeking alternative post-mine economic development opportunities utilizing existing mine assets. Accomplishments include development of an Asset Re-utilization and Post-closure Plan, a community survey regarding the impending mine closure, recruiting an international wind energy company to develop a wind farm, and development of an industrial/business park. The synergy of this strong partnership is key to meeting sustainability goals and enhancing potential future mining operations. The cooperative effort of the GSM and the local stakeholders is a success story that could be a role model for other mining operations.

Jan 1, 2004

By O. B. Bucklen

The Coal Research Bureau of the School of Mines at West Virginia University, using a modified design of a Russian flotation device, was able to obtain a clean coal product containing 7.64 percent ash with 94 percent yield and 97 percent coal recovery. This favorable performance was obtained with the semi-pilot scale flotation cell operating as a simulated three stage unit on slurry taken from the fine coal circuit of a coal preparation plant. This experimental device, consisting of a sheet metal cyclone-like unit mounted on a U-shaped uplift pipe, uses a combined flotation and cyclone action to beneficiate the minus 14 mesh partially cleaned feed product. In addition to providing comparable analytical results, the airlift-cyclone possesses other attractive features among them being a low capital expenditure, utilization of moderate plant floor space, efficient "operation on high density feed slurry, and absence of moving parts.

Jan 1, 1964

By Jerry L. Fuller

Fan performance graphs are generated by digital computer using two programs, RUN- FANS and FANPLOT. RUNFANS calculates fan performance data from stored specific-volume, specific-speed data for a given fan type with appropriate allowances for fan diameter, rotational speed and air density. FANPLOT accepts specifications for drawing the graph and accepts either user-supplied pressure-quantity data or RUNFANS- calculated data as input, Operational procedures for both programs are detailed and examples of their interactive query routines are included. The hardware necessary to generate the graphs is illustrated. Several hardcopy output options are discussed,

Jan 1, 1984