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By E. J. Karges

The use of pulverized coal for generating power and performing industrial processes has made an important contribution to our industrial economy during the past half century. Actually, the burning of coal in powdered form is a subject that has held the attention of engineers for a century or longer. Its widespread use, however, is comparatively recent, As early as 1866 patents were granted to Messrs. Whelpley and Storer for a method of feeding pulverized coal into a furnace as an auxiliary to the grate fuel. In the many tests made during the subsequent years with various kinds of apparatus, the experimenters were handicapped in not getting the coal fine enough to obtain complete combustion and to prevent excessive formation of slag.

Jan 1, 1965

By W. C. Lacy

It is the responsibility of educators to look ahead and prepare young engineers and scientists to cope with industrial and social problems of the future. We are faced with a review of history as well as prophesy of the future. The mining industry exists in a "bubble" with little interaction or communication with the outside. This isolation must be broken down if the industry is to survive in the U.S. and Canada. The ability to communicate with the general public and public officials is essential. Many changes are occurring that will require readjustments in technology and staffing. Aging population will result in raising retirement and increasing available workforce. This may force shorter working weeks to supply additional jobs. Environmental concerns will likely direct more attention not only to these concerns during mining, but to planning for post-mining land usage. Retraining and up-dating educational programs are required to cope with these changes.

Jan 1, 1994

By S. B. Kim, J. Hong, K. Park, W. Kim, H. Kim, Y. Han, J. Choi

"For the first time, the influence of stearyl trimethyl ammonium chloride (STAC) as a collector, on the flotation behavior of lepidolite (Uljin, South Korea) was systematically examined in Denver Sub-A cells. Flotation tests were carried out by varying amount of STAC (50–200 g/ton), feed size (-65, -100, -150, and -200 mesh), and solution pH. The impeller speed of 1000 rpm, flotation time of 10 min and AF-65 (a frother) of 250 mL/ton were invariably applied. In order to complement flotation experiments, zeta potential measurements and XRD analysis were conducted. XRD results showed that the ores were mainly composed of lepidolite, muscovite, quartz, calcite and albite. In addition, zeta potential results showed that isoelectric points were about 2.5, 2.3, and 9.7 for quartz, albite, and calcite, respectively, and lepidolite was determined to be less than 2. Overall, the results of 3-stage flotation showed that Li2O grade and recovery tended to increase with increasing STAC dosage and decreasing feed size. In addition, Li2O grade increased with decreasing pH. The results were explained by the extent of the interaction between STAC and each mineral.INTRODUCTION A great number of potential applications of lithium are being developed currently by the thermonuclear fusion power generation industry(1,2) as well as by the battery and fuel cell industry(3). Even though lithium is mainly consumed in the form of lithium metal and some lithium compounds, about 10% of total lithium production is consumed directly as mineral concentrates by the ceramic industry for the manufacture of special ceramics and mica based glass-ceramics(4). Granitic pegmatites normally contain feldspars, quartz, and mica in addition to lithium-bearing minerals such as spodumene (LiAl(SiO3)2), petalite (LiAlSi4O10), and lepidolite (KLi2Al(Al,Si)3O10(F,OH)2). The amount and grade of metallic minerals tend to gradually decrease and become lower, leading to the increase in the price of base metal or metallic compound(5). Accordingly, recent studies have been extensively devoted to developing the technique to improve the grade of metallic minerals from low grade metallic ores(6,7). Nevertheless, studies regarding the improvement of Li grade from lepidolite ores are very scarce. Lepidolite is a phyllosilicate mineral of the mica group and is often associated with other minerals such as calcite, muscovite, feldspar, and quartz, which need to be separated for lepidolite enrichment(8). Many studies have reported the flotation techniques for separating calcite, muscovite, feldspar, and/or quartz from various targeting minerals(9-11); however, there has been no attempt to investigate physico-chemical properties of lepidolite and its separation from such types of gangue minerals through flotation. Hence, in this study, for the first time, flotation has been carried out for the quaternary ammonium salts (stearyl trimethyl ammonium chloride (STAC, (CH3)3CH3(CH2)16NCl))-lepidolite system based on only the electrokinetic property of minerals that consist of lepidolite ores without adding any depressant to get an initial insight on its flotation behavior. The experimental variables that influence the lepidolite flotation such as amount of collectors, feed size and solution pH have been also examined."

Jan 1, 2015

By H. Huang, R. N. Gow

"Previously, Gibbs’ phase rule was applied to mass-balanced EH-pH diagrams for the Cu-As-S-H2O system. Diagrams were generated using the stoichiometry of enargite as a basis. In this study, the calculations were expanded to cover the stoichiometries of three other Cu-As-S minerals (tennantite, sinnerite, and lautite) and compared to enargite. Stability regions within the resulting EH-pH diagrams were found to change with stoichiometry such that a particular mineral would predominate if its stoichiometry was used in the calculation. Solution speciation was also found to vary, with thioarsenate being the best example. This stoichiometric effect helps to explain results reported in the literature and would be difficult to realize if it were not for mass-balanced calculations. INTRODUCTION A comprehensive thermodynamic review has recently been conducted on the aqueous copper-arsenic-sulfur system (Gow et al., 2014a-d). The free energies of over 100 species were collected from various authors and thermodynamic databases to produce mass-balanced EH-pH diagrams, using the thermodynamic equilibrium calculation software, STABCAL (Huang, 2014). The full database was listed and discussed by Gow et al. (2014A). Resulting diagrams were generated for enargite and confirmed with Raman spectroscopy using bulk mineral electrodes in order to identify reactions spectroelectrochemically. Theoretical calculations agreed well with the experimental results under alkaline conditions (Gow et al., 2014a), acid conditions (Gow et al., 2014b), and alkaline sulfide leaching conditions (Gow et al., 2014c). In this study, additional mass-balanced EH-pH diagrams are generated by changing the copper-arsenic-sulfur stoichiometry from enargite (Cu3AsS4) to tennantite (Cu12As4S13), sinnerite (Cu6As4S9) and lautite (CuAsS). Regions for the thermodynamically stable species are shown to change with the four different mineral compositions. Potential leach conditions, both for co-dissolution and selective dissolution techniques, were examined for differences in predominant species according to changing copper-to-arsenic ratios, sulfur compositions, and sulfur oxidation states."

Jan 1, 2015

By Weijie Wei, Jinwang Zhang, Jiachen Wang, Yang Li

"Longwall top-coal caving (LTCC) mining technique is one of the important methods for underground thick seam extraction in China. The coal seam in LTCC panel is divided into two parts: bottom-coal and top-coal. The bottom-coal is mined by conventional longwall method while the top-coal is mined by caving method. The top-coal caving process in LTCC and block caving process in metal mine are both gravity flow of loose ore/coal blocks. However, the presence of caving shield in LTCC makes the characteristics of drawing body shape in the two caving processes differ a lot. This paper discusses the influence of caving shields on the characteristics of drawing body shapes in light of recent studies of the top-coal drawing process. The theoretical model for describing the drawing body shape in LTCC is proposed both along the seam strike and seam inclination. Then, the experimental data are used to validate the correctness of the theoretical model. Furthermore, two examples of how the theoretical findings assist LTCC mining are given and discussed.INTRODUCTIONLongwall top-coal caving (LTCC) mining technique and large-cutting-height mining technique have been widely used for extracting thick coal seams in China. About 0.6–0.7 billion metric tons of coal come from longwall top-coal caving panels every year. The maximum annual production is 15 million metric tons per panel _The mining method employed in such panel is a combination of top-coal caving mining technique and large-cutting-height mining technique, which is suitable for seam height between 12–20 m, as shown in Figure 1. Apart from China, LTCC has also been employed in some coal mines in Australia and Vietnam (Le et al., 2017).The coal seam in a LTCC panel is divided into two parts: bottom coal and top coal. The bottom-coal is mined by the conventional longwall method, while the top coal is mined by the caving method. The top-coal caving process in LTCC and block caving process in metal mines are both gravity flows of loose coal/ore blocks, as shown in Figure 2. However, the presence of caving shields in LTCC causes the characteristics of the drawing body shapes in the two caving processes to differ significantly.There are two main differences between the blocking method and the top-coal caving method:"

Jan 1, 2019

By William M. Turner

Thermonics is a methodology of ground-water flow system analysis based upon the distribution of heat within the subsurface as influenced by moving ground water. Thermonics is based upon the Stallman Equation 1 (1) which describes the simultaneous transfer of heat through a porous medium which contains moving ground water. The Stallman Equation is:

Jan 1, 1980

By Richard Seal

Nabarlek is situated in the Arnhem Land Aboriginal Reserve about 270 km due east of Darwin in the Northern Territory of Australia. During the dry season (May to November) Nabarlek is accessible from Darwin over the Arnhem Highway-- a distance of 330 km. Throughout the wet season (December to April), except for a few days, access is provided by aircraft from Darwin to the Nabarlek airstrip. Because of the limited access during the wet season, reagents and supplies have to be stock- piled for six months on the site to maintain operations. With the mine and plant being remotely located on private Arnhem land with very limited access outside the site fence, operating personnel are flown to Darwin every six days for their days off.

Jan 1, 1980

By Carlos Fonseca, Gustavo Usero, Roberto Mentzingen Rolo, Gabriel Moreira, Octavio Rosa de Almeida Guimarães

Geological domain modeling is an important step in mineral resources evaluation. The procedure can be laborious and time-consuming, especially in multivariate settings. However, estimates are significantly improved when carefully limited by geological variables. This paper proposes a workflow for geological domain modeling suited for stratigraphic deposits. The workflow consists in automatically defining the domains by using clustering algorithms, generating the surfaces that represent the contacts by interpolation and subsequent triangulation, and simulating the surfaces. The proposed workflow produces consistent and realistic results and allows the user to test different domain configurations and assess volumetric uncertainty automatically and quickly.

Jun 25, 2023

By AJIT SWAIN, SUNATI MOHANTY

The abstract discusses the importance of predicting the dewatering performance of industrial hydrocyclones from laboratory models. It highlights the challenge of scaling up design and operating parameters for efficiency estimation. The paper describes experiments with a 2-inch and 4-inch hydrocyclone using silica sand. It details the development of a model using the Nageswararao hydrocyclone model and a simulator to estimate model parameters. The model is validated with experimental data, and a new model is developed using 4-inch hydrocyclone data. The technique is then extended to predict dimensions for a full-scale dewatering cyclone operating at higher throughput and solid concentration.

Mar 30, 2022

By S. C. Howell

The mining of taconite, to provide feed for a processing plant, requires that the flow of material continue uninterrupted. This means first, that the crude must be of a size acceptable to the primary crusher in order to reduce the delays caused by plugging the crusher with chunks. Secondly, elimination of oversize in the pit will reduce costs of all wear parts used in the mining and processing of taconite. Savings in wear parts is readily recognized in dipper teeth, bases, buckets, truck boxes, and crusher parts, both primary and secondary. During the early days of taconite mining, it was soon recognized at reserve mining company's Babbitt operations that experience in mining other ores was not always (or ?necessarily??) Applicable to excavating taconite. This was especially true in drilling and blasting. Blasting of small tonnages in single or double rows simply filled the pit with scattered chunks and provided very shallow banks for shovel loading. It also created problems for the jet piercers, since all drilling had to be performed in fractured areas. Drilling efficiency suffered and costs were extremely high. Shovel and truck efficiencies were also low and again costs were high. A high percentage of secondary breakage was required. This necessitated the use of numerous man hours to jackhammer holes in chunks, preparatory to loading and blasting. After the chunks were reduced, bull- dozer and grader hours were needed to pile the taconite for acceptable shovel loading.

Jan 1, 1968

By L. M. Pruett

The Arizona Legislature is currently in the process of considering mined land reclamation legislation in the 1994 legislative session. A bipartisan legislative study committee has drafted proposed mined land legislation. The committee has attempted to craft legislation that is appropriate for the unique conditions in Arizona. Existing Arizona and federal laws and regulations extensively regulate the environmental performance of mines in the state to protect public health, safety and the environment. The proposed mined land reclamation legislation does not replace or duplicate these statutory provisions relating to environmental protection. Instead, the purpose of the proposed legislation is to provide for the reclamation of land that is being mined and to fill the gap in existing laws by requiring the reclamation of land that currently is being mined or that has been mined since 1986 to provide for future land use. The legislation would require an operator to submit a reclamation plan describing the exploration operations, mining operations, post-mining land use and the proposed reclamation measures for review by a state agency. Financial assurance also would be required in an amount such that a third party could complete the approved reclamation measures. Arizona's mined land reclamation legislation would recognize Arizona's leading role in hard rock mining and emphasize the mining industry's economic importance to Arizona and the nation. Because mining operations necessarily require disturbing the surface of the earth to extract valuable minerals, reclamation requirements would be adapted to different conditions and would vary depending on site-specific conditions and on the commodity being mined. The current proposal does not identify the state agency that will administer the mined land reclamation program and approve reclamation plans, substantial changes to plans, and transfers of reclamation plans to other operators.

Jan 1, 1994

The stability of mine roofs in permafrost zones is determined mainly by temperature and ice content. The deformation resulting from creep and temperature dependent physical properties of frozen rockmass is the dominant component of total deformation. Roof bolts can consolidate the roof and control its deformation. In this paper, a finite element model for analysis of the effects of roof bolting in a frozen rockmass is presented. The model includes the variables normally encountered when analyzing the effects of roof bolting in rocks. It also accounts for properties unique to frozen rockmass, creep deformation and the change in Young's modulus with changing temperature. The model shows that, as bolt spacing decreases, there is a trade-off between increased roof stability from increased mechanical support and decreased stability from increased conduction of heat into the frozen roof. This result was expected, and shows that, for a given set of rockmass conditions, including ice content, temperature, particle size, etc., there is an optimum bolt length and bolt density for minimum roof deflection.

Jan 1, 1996

By Gerald L. Colborne

The major role of financial institutions in the free world in the development of mineral resources is to provide the necessary capital in the form of loans to underwrite the development of these resources by the industry on a stable and continuous basis. This capital provided by the depositors to the bank must be invested in sound projects where the degree of risk is relatively small, the return on the investment is reasonable and the time to retire the loan is of short duration. Money is, therefore, one of the important ingredients along with technology, manpower and an exploitable resource that will provide a sound economic base in this region of development. Canadian banks are similar to banks of other western nations, although each country has some differences in their banking systems. The basic difference between the American and Canadian systems is that the former employs unit banking while the Canadian utilizes the more mobile branch system, which is prohibited or restricted in the United States and some other countries. Canadian banks are the subject of this paper, so, subsequent material will relate to Canadian banks unless indicated otherwise. It will be realized by everyone that the mineral industry is only one area of the economy in which the banks are interested and to cover the subject matter in the time allowed, the topic is restricted to mineral resource development. In Canada this is a vital sector of our economy and before we outline some of the details of financing and services involved in various aspects of mineral development, a review of the Canadian mineral industry is a necessary part of the sequence of presentation. The writer presents this material as a resource engineer advising a major bank in mineral matters, so the presentation may relate more to the financial problems of the developer

Jan 1, 1972

By Verne Huser

The intensity of environmental conflict, the delays and legal battles that have marked the 1970's suggest the need for additional processes to resolve environmental disputes. Our present means frequently fail to address the real issues separating individuals and institutions. They are primarily adversary processes that foster polarization and reduce cooperative efforts. At the Office of Environmental Mediation, we have no quarrel with adversary processes nor with polarization, for both serve as important spurs to necessary change. We do seek cooperation among parties at a point where there can be a realistic expectation of success in facilitating a resolution of their mutual differences.

Jan 1, 1979

By Randall D. Peterson

Strip mining with draglines and other surface equipment has traditionally been the method of choice for mining shallow deposits. This is particularly true for soft deposits that require little or no blasting. High rates of productivity and low operating costs have set this standard. However, these methods can be improved. Strip mining methods are batch processes and difficult to accommodate in processing. Moreover, they are encumbered with overburden removal, reclamation expense, and human inefficiencies. This paper describes the invention of a novel shallow earth mining technique called the Softwall Mining Method. Softwall Mining is an adaptation of longwall mining for loose earth conditions. The method was specifically invented for recovering phosphatic clay ore from beds in North Central Florida, but is likely to be suitable for a number of other minerals as well. Potential deposits for which the method may be well suited include placers, disseminated deposits in soft host rocks, bauxite, soft coals and lignite deposits, and other deposits where overburden will subside readily and where the ore can be hydraulically broken and slurried. Unit operating cost advantages are expected over the current dragline systems used. The Softwall mining advantages are its high rates of productivity, control and automation of the mining process, reduction of dilution and waste, and elimination of the majority of stripping and reclamation.

Jan 1, 1998

By F. J. Bruey

Refdist is a simple but valid approach to planning or analyzing a test-vs-control plant trial that uses accumulated plant performance data to calculate objective criteria for judging the trial outcome. Refdist calculations and results are explained and illustrated with data typical of the mining industry. Findings from a simulation study of Refdist statistical properties are reported. Suggestions for dealing with messy data situations are offered.

Jan 1, 1999

By J. James Eidel

Geological interpretations generally require projections from direct observations at the earth's surface. Crustal projections include mineral deposits as well as the geochemistry of the crust and its fluids, structure and tectonics. Drilling offers opportunities for verification of the required projections, and is thus a required step in furthering crustal understanding. Like any new science, the direct observations that drilling provides commonly generate major surprises and stimulate totally new ideas. Drilling is costly. There are many critically important scientific problems with societal and potential economic benefits in mineral deposits which have not been drilled because the holes are difficult to justify as economically sound risks for private capital. Such holes, however, are highly justifiable research goals for government because of the significant new opportunity for ore deposit insight and exploration that they afford. The earth science community is prepared with excellent drilling projects for research in mineral deposits.

Jan 1, 1985

By N. L. Bingham

The mining industry's image is molded by what the general public knows, or thinks they know about mining. As we prepared for the production of Caterpillar's educational film, Common Ground, we first had to find out exactly what the public perceptions about mining were. Before we could educate people about mining, we had to find out what they already thought. As we broke down those perceptions, we were able to narrow our focus to relevant, realistic approaches for the film. We found out what people didn't know about mining. And most importantly, we singled out the facts they should know... facts that could create more favorable attitudes. This research was instrumental in our final direction for the Common Ground project.

Jan 1, 1994

By Doug Harding

The 3.5 km long Ashbridges Bay Outfall in Toronto, Ontario, Canada was a challenging drive set below Lake Ontario. After a remote machine acceptance due to the global pandemic, an 8 m diameter Single Shield machine launched in March 2021 from an 85 m deep shaft and began its bore in shale with limestone, siltstone and sandstone. During excavation, the TBM and its crew bored a city-wide record of 30 rings in one day, or 47 m of advance. This paper will cover the unique project, from TBM acceptance through to launch, tunneling in difficult conditions, and completion in 2022.

Jun 13, 2023

By Richard L. Gordon

Coal supply analysis has since about 1973 become a major activity of many scholars and consulting firms. The present paper is an effort to explain in as nontechnical fashion as possible the state of the art and what implications, if any, the research has for those actually engaged in producing coal or regulating the industry. l The discussion stresses the coal supply side of the models and makes limited comments about other elements in the analysis. To orient the appraisal, it is desirable to recall the features of coal supply that an adequate model should capture. The first considerations are the locational aspects of the industry. Transportation costs can, in some cases, exceed the production costs of coal, and thus any adequate model must incorporate a treatment of the economics of transporting coal from one location to another. A second major issue is that of the heterogeneity of coal; models should treat as well as possible such key differences among coals as their Btu and sulfur content. Third, we recognize that, with given technology and labor, capital, and supply costs, an expansion of the supply of a given type of coal in a specific region will occur only if prices rise. This is the familiar proposition of textbook economics that supply is an increasing function of price. Finally, over time, changes in technology, input cost, and depletion interact to cause changes in the price of given amounts of coal. Economics represents the net effect of this process by a shift over time in the supply curve. During the 1950s and 1960s, the trend was to reduce the production costs of a given output; subsequently costs rose sharply.

Jan 1, 1977