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By David Cronan

"Most of the recent renewed interest in manganese nodule mining has been focused in the Clarion-Clipperton Zone (CCZ) in the NE tropical Pacific where nodules are rich in Mn, Ni and Cu. However, equally interesting, but compositionally different, nodules occur in the tropical central South Pacific (CSP). The CC Zone deposits lie in the International Seabed Area whereas those in the South Pacific lie mainly in the Exclusive Economic Zones of Island States, principally the Cook Islands and Kiribati. The CSP nodules should not be regarded as an alternative resource to CCZ nodules, as they are enriched in different elements. Rather, the CCZ nodules should be thought of as a source of one group of metals (Mn, Ni and Cu) and the CSP nodules the source of another group (see below), mutually complementing each other and to be mined in parallel for their different metals.Manganese nodule mining in the South Pacific has been mooted since the 1970s. However, new data on manganese nodule composition and abundance there have recently appeared. Also, a recently developed interest in 'rare', 'green' and 'technology' elements has necessitated a re-examination of old South Pacific nodule data for information on these elements (previously thought to be economically unimportant), and the re-analysis of the deposits to obtain new data on them. Additionally, current and possibly future applications to the UN to extend island 'continental shelf' areas necessitates an appraisal of the manganese nodules in these areas. These developments have prompted recent work that has helped to refine our understanding of the distribution and abundance of metals of traditional interest in South Pacific nodules, namely Mn, Co, Ni and Cu, but has also drawn attention to other elements of possible economic interest including titanium (Ti), vanadium (V) and the rare earth elements (REE)."

Sep 1, 2014

By Y. C. Kim, F. Szidarovszky

G.M. Philip and D.F. Watson The article cited above reflects the difficulty that is often encountered in interpreting different aspects of kriging. Baafi et al. write : "Due to negative kriging weights, negative block grades may be obtained in some extreme situations, which makes no practical sense." Their solution to this particular problem is to constrain the kriged estimates to data values that have positive weights, i.e., reduce the subset size contributing to the estimation. As Journel (1986, p. 133) has already observed, "Negative weights are no evil." Indeed, they are an ineluctable result of the Lagrangian multipliers in the system of simultaneous equations. The fact that data distant from the estimation point may be given negative weights simply means that the influence of such distant values must be negated because their influence is contradictory to closer values (as illustrated by Baafi et al. in their Figs. 3 and 4). Of course negative kriging weights applied to distant grade values will not in themselves induce negative grade at some central interpolation point. Negative grade values, rather, seem to be a particular artifact of automatic methods of estimation involving accu¬mulations (Philip and Watson, 1985a, 1985b, 1987b). The elimination of negative weights, suggested by Baafi et al., is likely to exacerbate a quite different problem of kriging and piecewise spline interpolation discussed elsewhere (Philip and Watson, 1987a). In interpolating large data sets of scattered observations, changing local subsets or neighborhoods must be selected automatically. Because of the mathematical formulation of kriging and spline interpolation, discontinuities then occur between closely-spaced estimation points as the subset used in the estimation changes. If this subset is reduced in number and size, the discontinuities will be amplified and more common. ? References Journel, A.G., 1986, "Geostatistics: models and tools for Earth Sciences," Journal of Mathematical Geology, Vol. 18, No. 1, pp. 119-139. Philip, G.M., and Watson, D.F., 1985a, "Theoretical aspects of grade-tonnage calculations," International Journal of Mining and Geological Engineering, Vol. 3, pp. 149-154. Philip, G.M., and Watson, D.F., 1985b, "A deterministic approach to computing ore reserves. I, Grade Estimation," Earth Resources Foundation, Occas. Paper 2, The University of Sydney, 24 pp. Philip, G.M., and Watson, D.F., 1987a, "Neighborhood discontinuities in bivariate interpolation of scattered observations," Mathematical Geology, Vol. 18, No. 1, pp. 69-74. Philip, G.M., and Watson, D.F., 1987b, "Estimating interactions of topological functions," Mathematical Geology, Vol. 18, (at press). Reply by Y. C. Kim Before replying to the comments by Philip and Watson, it is desirable to establish the original perspective of our paper, which was intended primarily for the practitioners of mining who possess a working knowledge of ordinary kriging. The paper tried to convey the following practical points: (1) there are circumstances in which one observes negative weights, (2) illustration of circumstances under which one can expect negative weights, (3) should one obtain a negative estimated grade, one can resort to elimination of negative weights using the technique outlined in the paper, and (4) one could normally select only the first layer of surrounding assays to estimate the block grade. Under such a perspective, most of the comments by Philip and Watson are irrelevant and misdirected. For example, the practitioners do not find it difficult to "interpret" the results of ordinary kriging, as evidenced by the fact that they have been using the results for nearly a decade. Nor are the practitioners concerned with discontinuities in estimated block grades due to changing neighborhood of assays during kriging. What matters to the practitioners is the fact that kriging does provide the best estimate among all the estimation tools available to them as of today. ?

Jan 2, 1987

St. Peter sandstone is an arenaceous sheet that covers large area in North America. The interest for St. Peter sandstone has been increasing due to the upward trend for hydrofracturing and the consequent need for fracking sand. This material is possesses very unique mechanical properties. On the one hand, it is brittle as characterized by an unusually high friction angle, up to 69°, and steeply curved failure envelopes. On the other hand, it is friable, possessing extremely low, and in most cases zero cohesion. The underground mines that are working under this condition are lacking the ground control techniques for this particular mining environment. The geotechnical properties of the St. Peter sandstone were examined using uniaxial test, triaxial test, porosity test, flexural strength test. This paper aims to investigate the effect of microstructure on strength properties, utilizing microscopic studies, index test (porosity, size distribution).

Feb 23, 2014

By Lei Zhang, Zhibo Ma, Pingye Guo

The mechanical behavior of hard roofs often leads to significant deformation and strong mine seismicity in gob-side entry retaining (GER) of the longwall mining, affecting the mining safety and efficiency of coal mines. Field investigations indicate that the failure process of the retained entry by hard roofs can be divided into three stages. In this paper, theoretical analysis and numerical simulations are first used to evaluate the damage process of the retained entry under the hard roof. The results show that the instability of the retained entry in the conventional GER method results from the combined static-dynamic loads (in stage II and stage III) from the hard roof. Then, an innovative method, through fracturing roofs to maintain entry (FRME), based on GER with the hard roof is introduced to solve this problem. In this method, the roof of the mining area is pre-fractured, and when the coal seam is mined, the direct hard roof will collapse along the fractured surface due to its deadweight and mining pressure. The hard roof control effect on the static and dynamic loads, taking into account the innovative method, is verified with simulations and theoretical analyses. The results are compared with those of the conventional GER method. Furthermore, based on the numerical simulation study of dynamic responses, it is found that compared to the GER method, the dynamic response of the retained entry using the innovative method is more moderate and more conducive to the stability of the entry. Field application also validated the effectiveness of the innovative method to control the mechanical behavior of the “massive sudden collapse” of the hard roof.

Aug 14, 2023

By Lingyun Zou, Xinghai Lei, Tiezheng Li, Yifei Song, Nan Wang, Yang Li

The stability of key strata is of utmost importance in ensuring safe and effective coal seam mining operations. To minimize disturbance impacts on these strata and ensure their stability, it is crucial to assess the degree of disturbance caused by mining activities. This study proposes the evaluation index “disturbance degree of key stratum (KSDD)” and establishes a quantitative KSDD criterion to measure the degree of disturbance on key strata. To facilitate the assessment process, an intelligent calculation system for KSDD is developed. The classification criteria are derived by combining the measured three-zone heights from multiple mines. The reliability and accuracy of the KSDD quantitative criterion are validated using field measurement data. Furthermore, the KSDD quantitative criterion is applied to the Meihuajing mining area No. 23, and the distribution characteristics of KSDD are analyzed. The findings of this study can serve as a valuable reference for reducing disturbance and enhancing the stability of key strata during subsequent mining operations. Overall, this work contributes to the field of ground control in coal seam mining by providing a comprehensive approach to assess and mitigate the disturbance caused by mining activities on key strata.

Mar 8, 2024

By Mustafa Kumral, Yuksel Asli Sari

Underground mining operations are sensitive to price fluctuations because they usually perform with a narrow profit margin compared to open-pit mining. Furthermore, the economic evaluations regarding operation are based on estimated or simulated grades rather than actual values. These bring a high degree of uncertainty to the viability of an operation. Hence, mine planning that accounts for uncertainty is crucial for underground mining operations. As an underground mining technique, sublevel stoping has geotechnical, curing time, seismicity, cost minimization, and production requirements. A new mixedinteger linear program is proposed that considers the uncertainty associated with net present value using chance-constrained programming. The net present value (NPV) maximization objective is transformed into a multi-objective maximization problem where one objective is to maximize the mean NPV, and the other objective is to maximize the negative standard deviation multiplied by a scalar called risk or reliability level. The balance between the two objectives was maintained by this scalar and was selected based on the reliability level of the project. A case study was conducted with varying reliability levels, and sequences were generated. It was shown that the expected net present value increased at higher reliability levels, and the overall value of the objective function decreased as the reliability level increased. In other words, the variance component penalized the value of the objective function. Moreover, it was observed from the case study that at lower reliability levels, stope grade order bears similarity to the extraction order.

Aug 4, 2023

By Doug Halbe

A number of CIP plants have been built in Western Australia in the past two years. The authors have surveyed several of these new plants and present drawings, data and discussion of operating and design innovations and areas of interest.

Jan 1, 1982

By Thomas A. Palmer

Free cyanide has been successfully determined in ground and surface water by isolation using a microdiffusion technique followed by a pyridine-barbituric acid photometric finish. The determinable free cyanide includes hydrocyanic acid, ionic cyanide, and the cyanide of weak complexes such as cadmium, lead, manganese, and zinc cyanide. Complexes of copper, iron, nickel, and silver are sufficiently strong so the dissociation into free cyanide does not occur at the microdiffusion pH 7. Cyanate, sulfide, and thiocyanate do not interfere. Samples containing as little as 0.005 mg/L are successfully analyzed. The relative standard deviation is <10%. Samples stored at pH >I2 in the dark are stable at least three weeks.

Jan 1, 1981

By Jerry Dolph

In September 1855, 55-year-old Noah Spencer Kellogg and his $3 jackass named Bill discovered what was known at the time as a “blow out” of high-grade lead and silver ore. The deposit was located on the side of a North Idaho mountain high above the South Fork of the Coeur d’Alene River. The ore was later assayed at 41,141 g/t (1,200 oz/st) silver. Kellogg named his discovery the Bunker Hill Lode, after the June 17, 1775 Revolutionary War battle of Bunker Hill. A thriving pioneer settlement sprang into existence around the resulting mine’s workings and was eventually— and appropriately — named Kellogg. The peak rising hundreds of feet above the mine’s adit was named “Jack-ass Peak” after Noah Kellogg’s hairy companion.

Jan 1, 1996

By Ping Zhang, Xu Ma

Perturbations arising from mining operations significantly affect the stability of rock masses, and the influences aggerates with the rapid increase of mining-operation depths during recent years. The subsurface structures with major discontinuities subject to seismic hazards resulted from the shear-slip behaviors of rock masses. In order to identify the shear-slip regime of discontinuities and calculate seismic moment and seismic energy involved with shear-slip behaviors, we use discrete element modeling to study the shear slip failure along discontinuities in an underground mine. The recorded characteristic and properties of sub-contacts in DEM provide a basis for computing and visualizing the temporal and spatial distribution of seismic moment and seismic energy with mining operations. We computed the seismic energy and seismic moment using the numerical modeling method and the analytic method. We compared the result of summing seismic energy and seismic moment from the subcontacts of numerical models and the result of the analytic method. We confirmed that this tool can be used in comparative analyses. We also found that seismic moment and seismic energy, associated with shear stress drop and shear displacement increase, accumulate in the vicinity of major discontinuities. Mining operations at a greater depth cause greater changes of seismic moment and seismic energy, leading to a higher risk of inducing seismic hazards. Quantifying seismic potential using discrete element modeling can greatly facilitate the investigation of instability of geological discontinuities and thereby can help estimate the potential of seismic hazards.

Jan 21, 2023

By J. Iannicelli

Spray drying is the principal drying method used in the production of over six million tons annually of beneficiated kaolin in Georgia. Thirty-three dryers in the Georgia Kaolin belt comprise the highest concentration of large tonnage spray dryers in the world. The steady growth of spray drying in the U.S. kaolin industry is paced by advances in design and development of large spray dryers which have led to large scale new applications in mining and related industries.

Jan 1, 1982

By Donald P. Richards

Is a shaft the same as a tunnel and can it be approached in the same manner for design and construction? The most obvious difference between a shaft and a tunnel is that of orientation; whereas a tunnel is commonly near horizontal or slightly dipping, a shaft is commonly vertical or steeply inclined. As a result, design and construction methods employed for tunneling, in general, cannot be directly applied to shafts, although some of the basic concepts of behavior are quite similar. Many of the shafts that have been sunk in various parts of the world are owned by private mining companies. Each company has generally accumulated years of experience in shaft sinking and mining techniques pertinent to its particular geographic location. When a new shaft is to be sunk or an existing shaft deepened, the tendency often seems to be to continue to use the methods that have been used successfully in the past.

Jan 1, 1979

By P. M. Hawley

In April 1975 Kaiser Steel Corporation and the United States&apos; Department of Energy entered into a cost-sharing agreement for the demonstration of shield-type longwall supports on three consecutive longwall panels at Kaiser&apos;s York Canyon&apos; Mine in New Mexico. Under this agreement the Department of Energy supplied 117 Hemscheidt 320 HSL caliper-type shield supports and hydraulic pumps for the duration of the demonstration. The purpose of the demonstration was to educate the U.S. coal mining industry as to the benefits in production, productivity, health and safety, and increased coal extraction afforded by shield-type longwall mining systems and to provide the industry with a working model. A detailed description of this demonstration is given in U.S. Department of Energy Publication No. DOE/ET/12530-T1, entitled "Demonstration of Shield-Type Longwall Supports at York Canyon Mine of Kaiser Steel Corporation," hereafter referred to as the York Canyon Report.

Jan 1, 1984

By Ping Li, Baokun Zhou, Lei Yang, Changfeng Li, Erhui Zhang

A uniaxial compression experiment was conducted on standard sandstone specimens to explore the sandstone’s mutation characteristics and early warning interval during deformation and failure. Meanwhile, acoustic emission (AE) and digital image correlation (DIC) techniques were introduced to realize multi-field analysis and cross-validation from the stress field, deformation field, and elastic wave field. The mutation characteristics of rock failure were investigated based on the cusp catastrophe theory. The results showed four mutation points in the destabilization process of sandstone: compressional density, yielding, destruction, and residual retention. As an internal activity characteristic of the sandstone failure process, AE directly reflected the dynamic failure process of sandstone. The stress variation was closely related to the evolution of AE characteristics. Sandstone loading failure was a process of the mutations of releasable elastic strain energy, dissipative energy, and releasable elastic strain energy. The mutation of dissipative energy was used as the starting mark of the sandstone warning state, and the second mutation of releasable elastic strain energy was used as the end mark of the sandstone warning state. Besides, the warning range corresponded to the loading time of 178 to 208 s. Finally, the sandstone instability warning interval was re-determined from deformation field evolution characteristics in the sandstone damage process, with a loading time of 180–204 s. This was consistent with the warning interval specified using the cusp catastrophe theory. The combination of AE, DIC, and cusp catastrophe theory revealed the mutation characteristics and early warning interval of sandstone failure. Hence, the results provide significant importance to predicting rock failure.

Aug 23, 2023

By Northcutt Ely

My topic today is our Nation&apos;s interest in the minerals beneath the oceans. I will state what I think should be our objectives, the means available to attain these objectives, and the obstacles to their accomplishment. It is possible that as early as this year of 1969 our country must make policy decisions on this subject, and that these, once made, will be almost irreversible. Two factors are hastening an. early decision. First, the 1958 Convention on the Continental Shelf becomes eligible for amendment after June 10, 1969, if the Assembly of the United Nations so decides. Second, the United Nations has created a permanent committee of 42 nations, which was preceded by an ad hoc committee of 35 nations, to study the question of the peaceful uses of the seabed "beyond the limits of national jurisdiction. While these measures purport to deal with the creation of a regime to govern mineral development on the deep sea floor beyond the limits of the jurisdiction of the coastal nations, it has become clear that the urgent issue is the extent to which this future regime shall acquire jurisdiction over the mineral resources of the continental margin, and receive royalties therefrom. This brings the proposal into potential collision with the interests of the coastal nations under the 1958 Convention on the Continental Shelf, including, of course, the United States.

Jan 1, 1969

By Robert P. King

In April, 1975 the Colorado School of Mines began monitoring rock mass response associated with a long- wall shield demonstration project near Raton, New Mexico. This project was sponsored by the U. S. Bureau of Mines (DOE) and performed at Kaiser Steel Corporation&apos;s York Canyon Mine. Two of the results of the intensive instrumentation effort are the empirical subsidence and horizontal strain models presented herein. These models are based on data gathered during mining three adjacent longwall panels (4N, 5N and 6N). A total of 251 permanent surveying monuments were monitored over the three-panel area. Lines of monuments were oriented along panel centerlines, perpendicular to centerlines and diagonal (45O) to centerlines. Active monuments were monitored twice a week, with less frequent monitoring of stable or slow moving monuments. Primary subsidence monitoring equipment consisted of an AGA Geometer Model 75 and a Wild T-2 Theodolite with -a Wild-Sercel DI-3S distomat.

Jan 1, 1979

By Manuel Gomez

This report presents prediction equations for eleven factors indicative of metallurgical coal quality which have been developed from data obtainable during exploration. Five coke strength parameters and six carbonization product yields have been predicted for coking coals having volatile matter contents in the range 16.3 to 42.1 percent, dry basis. The prediction models developed contain information from the proximate and ultimate analyses, the size consist, and the petrographic composition of coking coals carbonized in BM-AGA retorts at 800°, 900°, and 1,000°C. The equations reported have been evaluated with independent data derived from the 900°C carbonization of 33 binary blends. Present results show that metallurgical coal quality can be predicted ahead of mining. Capability to forecast coal quality is useful in mine planning and should provide basic information for optimization of blending and crushing techniques, leading to the production of uniform coke.

Jan 1, 1968

By Myles E. Robinson

During the last decade there were pronounced changes in the competitive pattern of the fossill fuels It is proposed to trace these trends and describe inter-fuel competition, first as it relates to the economy as a whole and then more specifically to examine competition of the fossil fuels as these share the electric utility market. Table 1, Competitive Fuels and Water Power Used in the United States, 1950-1959, shows the growth in the consumption of coal, oil, gas and water power &apos;during the past decade. Uses which are not directly competitive among the fuels, such as tractor fuel, carbon black, and consumption of petroleum products in the making of synthetic rubber, have been excluded from these statistics. The experience of the three fossil fuels in competition since 1950 shows natural gas expanding more rapidly, than oil by roughly twice as much, 219.0 percent&apos; compared to 124.1 percent growth in B.t.u.s of oil consumed in the ten-year period. Percentagewise, water power little more than held its own, and coal, including anthracite, actually decreased more than one-fifth.

Jan 1, 1961

By C. A. Holley

The generation of coal fines is a growing problem which has serious environmental and resource recovery Impact. Several methods of agglomeration are studied including the production of briquettes for the consumer market. Simplified process flow diagrams, "order of magnitude" plant capital cost and operating costs are presented.

Jan 1, 1986

By M. T. Webster

Views about the proper aim of public policy are, of course, matters of perspective and debate. Regardless of perspective, one would assume some consensus around the view that public policy ought to encourage mine operators to seek independent and critical assessments of worker safety and health at their operations through voluntary auditing. However, a review of the law on this topic shows that there is little to no manifestation of such a policy. Indeed, the balance of this paper, with a couple of exceptions, is devoted to the existing legal pitfalls that should be considered before a safety and health audit is conducted at a mine. While attorneys, particularly litigators like the author, might tend to focus on the potential problems that could arise from any given situation, the fact that most of this paper is devoted to potential legal concerns associated with auditing is a realistic reflection of the current state of the law. Specifically, this paper addresses the interplay between voluntary safety and health audits conducted at mines regulated by the Mine Safety and Health Administration (MSHA), and the administrative and civil legal issues related to such audits. The paper first provides an explanation of how and by whom an audit is conducted. The paper also addresses whether voluntary safety and health audits may be considered privileged and kept confidential in administrative and civil proceedings. Finally, selected legal issues related to such audits that could arise in administrative and civil litigation are discussed.1

Jan 1, 2012