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Little knowledge is available that considers the effects of continuous miner position on the possible respirable dust exposure of the remote mining machine operator. Such information could be very useful for increasing the awareness of the remote operator as to those parts of an extended cut that generate higher levels of respirable dust. This data could be used to develop guidelines for positioning the remote operator to reduce his potential exposure. This work details the effects of continuous miner position on dust levels measured on the machine and at the remote continuous miner operator location.

Jan 1, 1998

I found the article most interesting and timely. I consider it imperative that mine case studies like this one are undertaken and published so that the practicing mining engineer and geologist can obtain a better idea of what is the preferred estimation and grade control technique to use, given the site-specific geology, grade distribution, etc. Mining companies, with operating gold mines, need to be encouraged to either initiate such a study in-house or support a research project by financing a graduate student at a local university. The latter method is preferable since it not only provides research support but also an excellent training opportunity for young mining engineers and geologists. Ideally, what is needed is exploration drill-hole, blasthole, and mine production data that can then be used to assess the efficiency of different estimation and grade control methods by comparing the results obtained using the drill/blasthole data with the actual production data. It is hoped that more mining companies will realize that the rewards from this kind of research greatly outweigh the sometimes perceived problem with releasing data to a university. I noticed that the authors used the blasthole data to represent the actual values, the validity of which relies heavily on the two key assumptions with regards to blasthole assays and in-pit ore-waste selection procedures. Could the authors comment in more detail on these assumptions and what criteria they used to check the validity of the assumptions? Since the article was published, have the authors had the opportunity to compare their estimates with the actual production data? It would be interesting to compare other estimation methods with OK and IK. For example, how well did the polygonal method used at the mine compare with the results given in the paper? I would like to mention that B.L. Kwa completed a similar study (Kwa and Mousset-Jones, 1986) using exploration drill-hole, blasthole, and production data from the Alligator Ridge mine in Nevada. The study compared a variety of estimation methods, including IK, and the final results are shown in Fig. 1. The IK method exhibits the smallest difference between estimated and production results and is closely followed by the indicator moving window (Ind MW) method. Reply by Y.C. Kim We do concur with Professor Mousset-Jones with respect to the merit of such case studies performed at a local university. In answer to his request for comment on the validity of the two key assumptions made in our paper, we can only say that these are reasonable assumptions that are very difficult to validate. The assumption of blasthole assays being accurate can be partially validated by a careful analysis of the nugget component of blasthole variograms. The assumption that the in-pit ore-waste selection procedure in use was an effective one can only be validated through comparison between the mine estimates of ounces of gold versus the actual recovered ounces of gold at the mill. Neither one of these two assumptions has been validated to date due to several reasons. For example, the mine went through a change in management since the study. Similarly, no compelling reasons have been presented to perform detailed variogram analysis of the blasthole data. We do, however, believe that the obtained results (i.e., indicator kriging performs better than OK in a highly skewed deposit) will remain the same in relative terms, regardless of how valid these two assumptions may be. The most recent com¬parative study by D. S. Lindsey of the Montana College of Mineral Science and Technology also shows a similar ranking between ordinary kriging versus probability kriging, which is an extended version of indicator kriging.

Jan 1, 1987

By H. E. Rudi

The advent of open nit mining permitted the development and processing of minerals never before thought possible. New equipment was needed; new techniques were devised; new methods were called for. This development and acquisition of new techniques, methods and equipment did not, however, stir the souls of our industry and educational leaders sufficiently to a recognition of the problem of people, especially the future development of the people needed in open-pit mining. The people problem has been and will be with us as long as there are two of them. The development of people will be required for the same reason. The problem of developing future personnel for open-pit mining is not what must be developed; that is known to all of us and can be briefly stated ashore and better of everything." As I see it, the real problem lies in determining (1) what personnel are really critical, (2) why are they critical and (3) how can we develop them.

Jan 1, 1965

In 1992, United States mine production of barite decreased 8.5%. Barite consumption, sold or used by grinding plants, decreased by 36.9% and imports decreased by 61.6% vs. 1991. World mine production decreased 1.5%, according to the US Bureau of Mines. The value of domestically produced barite, f.o.b. mine, decreased 11.9% according to the Bureau. The declared value, c.i.f. United States port, of all imported crude barite during 1992 decreased from $42.35/t ($38.42/st) in 1991 to $40.09/t ($36.37/st). Nevada continued to be the leading producer of barite with 88% of the total, followed by Georgia and Missouri. It is estimated that 80% of the domestically mined barite was used as a weighting agent in drilling fluids. The remaining 20% was used in barium chemicals, glass or as a filler. Most of the production from Missouri, Georgia and Ten¬nessee was used in the non-oilfield sector. Of the total barite used by grinding plants and chemical manufacturers, it is estimated that 90% was used in drilling fluids and 10% in the non-oilfield sector. This included barium chemicals and fillers in paper, plastics and glass. The tonnage consumed in the drilling fluids market decreased due to the lower average rig count during 1992. The average number of rotary rigs operating (717) was 16.6% less than the 1991 average of 860 in the United States. Crude barite imports were 518 kt (571,000 st), 61.6% less than in 1991. Imports accounted for 44.7% of the barite consumed (apparent) in the United States. During the year, China continued to be the leading exporter of crude barite ore to the United States with 67.2% of total crude ore imports. India followed with 31 %, and others with 1.8%. About 90% of the imported barite ore was used in the oilfield sector. Ground barite imports decreased from 46.3 kt (51,000 st) to 30.9 kt (34,100

Jan 1, 1993

By E. R. Hoskins

The Gulf Coast States ranging from South Texas to Alabama contain vast resources of lignite ranging in energy content from about 4000 to 7000 Btu/lb (as-received) with sulfur content ranging from about 0.5 to 2 percent. Currently, the strip mining rate is about 35 million tons per year in Texas and essentially zero in the other Gulf Coast states. Estimates of future mining rates are as high as 310 million tons per year by the year 2000 with 240 being in Texas. In this paper, we examine the life cycle of the surface mineable lignice based on the most recent estimates of surface mine recoverable resources with two scenarios. The first indicates that a 310 million tpy rate could be sustained for only 15 years while the second scenario suggests that the 310 million tpy could be sustained for 25 to 30 years. If lignite resources are required beyond those that are surface mineable, the deep basin lignite will be developed. Five strategies for developing deep basin lignite are discussed.

Jan 1, 1983

By W. L. Hollinshead

For more effective and cost saving production in tunnels, the machinery used on construction sites will be equipped with guidance systems combined with working procedure management systems. This paper describes sensors for these systems and various system configurations. A project is described which uses a computerized guidance system on an underground mining machine for guidance and profile control.

Jan 1, 1999

By J. Klemenic

This paper presents an analysis of gold production and prices over an extended period. Production patterns are provided for the world as a whole and for the five major producing countries. Gold prices as a function of interest rates, as measured by municipal bond rates, are given for the period 1947 to the present. World gold production has had a phenomenal increase since 1980, with the exception of South Africa, all major producing nations participated in this increase, even though the price of gold generally has been decreasing since the high level attained in 1980.

Jan 1, 1993

By Edwin H. McKee

Eruption of rhyolitic ash-flow tuffs in the area of the McDermitt (Cordero) caldera began about 17.4 m.y. ago and continued for about 1.5 m.y. During this period of silicic eruptions, a circular area about 30 km in diameter collapsed to form a caldera that subsequently filled with sedimentary and volcanic rocks. 3 A total of more than 200 km of silicic rocks was erupted from the volcano. The final phase of igneous activity, about 15.5 m.y. ago, included resurgent doming and intrusion in the central part of the caldera. Three to 4 m.y. later +I2 m.y. ago), hydrothermal solutions using the northern part of the caldera ring fractures as conduits deposited cinnabar, pyrite, alunite, and other minerals in tuffaceous lake beds and volcanic rocks accumulated within the caldera. The ore-forming solutions may have been a residuum from the silicic magma or connate water or ground water heated by the still-hot resurgent magma in the central part of the caldera. The source of the mercury has not been identified. Later oxidation of the sulfide minerals and redistribution of the supergene minerals corderoite, several mercury nitro-oxychlorides, marcasite, iron, and titanium oxides in the sedimentary rocks account for most of the newly discovered ore body at Cordero.

Jan 1, 1976

By P. Soros

Rich iron ore deposits were discovered during the 1960's in the mountain range of Serra dos Carajas, State of Para, Brazil, near the headwaters of the Tocantins River some 400 miles southwest from the state capital of Belem. (See Fig. 1 and 2). The key to the successful exploitation of this deposit was the development of an efficient an economical transportation system. The rugged terrain, and the dense tropical vegetation of the Amazonian jungle and the irregular coastline with its high tidal range presented severe obstacles to the planning and building of such system. Starting in 1972 extensive surveys and studies were carried out by Soros Associates on behalf of CVRD to determine the optimum way of transporting the ore from the mine site to the markets, most of which are located overseas. Overland transportation to the coast, loading into seagoing vessels and the ocean voyage to the ports of destination was treated as an integrated system in these studies.

Jan 1, 1986

By K. Fuenkajorn

Geomechanics and geohydrological considerations for the seal design for mine openings are presented. Design guidelines derived from laboratory and in-situ experiments are proposed. The results suggest that seal design, specifications and material selection should be site-specific. Performance requirements for a specific seal location should be identified. Evaluation of sealing effectiveness should be made on the entire seal system, i.e. seal, seal-rock interface, excavation-induced damage zone and the surrounding rock.

Jan 1, 1997

By H. J. Brown

Pluess-Staufer (California) Inc. Lucerne Valley California operation is one of the largest producers of high brightness high purity fme grind limestone products in western North America. The San Bernardino Mountains area of southern California contains the largest high brightness, high purity limestone mining operations and undeveloped reserves in western North America (Fig. 1, Brown 1987). Combined annual production of high brightness limestone products from several operations is approximately 1.5 million tons, with an estimated gross value of $75 million dollars per year (Fig. 2). An additional 5.0 million tons of cement grade limestone is mined by several large cement producers in the nearby Mojave area (Brown, in press). The purpose of this paper is to summarize the geologic setting, genesis and mining of white, high purity crystalline limestone by Pluess-Staufer (California) Inc.

Jan 1, 1994

By ERIK CHARRIER, HUGH MILLER, JOSEF BOURGEOIS

In this study, a unique excavation system was characterized using waterjet technology as the primary tool for material removal during rehabilitation of reinforced concrete and shotcrete structural liners. Through empirical testing, this research seeks to validate the hypothesis that waterjet removal of these support systems will result in less unintended damage than conventional removal methods. The intent is to develop a viable technology that will reduce the collateral damage caused to surrounding liners during excavation, improve the adhesion between shotcrete and the substrate for longer lasting ground support, and improve overall safety for workers in underground environments. An analysis on the fracture mechanisms and operating parameters of each method was completed. Instrumented shotcrete panels were physically tested and examined through visual inspection and ground penetrating radar (GPR) to compare substrate damage according to each testing method. After testing was completed, the data strongly indicate that waterjet cutting causes less collateral damage to the surrounding intact liner and substrate than conventional impact hammers. This research is intended to provide a scientific basis for additional applied research in the rapid excavation and repair of shotcrete support systems.

By S. S. Xue

A study has been conducted to remove iron from sulfate solutions using Eichrom's Dipex® extractant, P,P?-di(2-ethylhexyl) methanediphosponic acid (H2DEH[MDP]). It is found that this extractant can effectively and selectively extract ferric ion from highly acidic solutions. Ninety-nine percent of the iron was extracted from a simulated feed solution in a single stage. The separation factor, Fe/Zn, was 10 6 Over 90% of the iron in a loaded organic can be recovered in an aqueous solution by reductive stripping. This paper presents the experimental results. A new process for iron removal using Dipex extractant is described and discussed.

Jan 1, 1999

By M. A. Cristovici

The possibility of using surfactants as wetting agents for the suppression of sulphide ore dust has been investigated. Numerous surfactants were examined to determine their characteristics and to investigate their ability to improve the wetting of the sulphide ore dust. However, the surfactants selected as suitable dust suppressors proved to have a negative effect on the flotation of the ore contaminated with such reagents. A method was developed to eliminate the detrimental influence of dust-suppressing surfactants. It consisted of surfactants adsorption on activated carbon and separation of loaded carbon prior to flotation. The technique is simple and requires minimal changes in the plant flowsheet.

Jan 1, 1990

By W. R. Reed, S. Klima, J. Driscoll, T. W. Beck

"Tests were conducted to determine properties of 4 foam agents for their potential use in longwall mining dust control. Foam has been tried in underground mining in the past for dust control and is currently being reconsidered for use in underground coal longwall operations in order to help those operations comply with MSHA’s lower coal mine respirable dust standard (1.5 mg/m3). Foams were generated using two different methods. One method used compressed air and water pressure to generate foam, while the other method used a low pressure air generated by a blower and water pressure using a NIOSH developed foam generator. Foam property tests comprising of a bottle shake test, foam expansion ratio, and water drainage were used to classify foams. The bottle shake tests determined that the lowest concentration of foam agent to be used was approximately 1.5%. Compressed air generated foams tended to have low expansion ratios (10-19) with high water drainage. Blower air generated foams had higher foam expansion ratios (30-60) with lower water drainage. Foams produced within these ranges of expansion ratios are stable and potentially suitable for dust control. The different foam agents produce foams with different material properties. Results of testing eliminated two foam agents for future testing because they had poor expansion ratios. The remaining two foam agents, while having different foam properties, seem to have properties adequate for dust control. These material property tests can be used to classify foams for their potential use in longwall mining dust control. INTRODUCTION About one-half of U.S. underground coal is produced by longwall mining. This technique allows for mining high volumes of coal, producing significant amounts of coal mine dust. This can lead to the overexposures to longwall miners and possibly occupational respiratory diseases black lung and silicosis, which have no cure and can be disabling or fatal. The only method to avoid these occupational illnesses is through elimination of exposure to respirable coal mine dust and crystalline silica (quartz). The current occupational exposure limit for respirable coal mine dust is 1.5 mg/m3 during each shift that a miner is exposed in the active workings of the mine or in mine facilities [1]. When respirable quartz is present, the mine must maintain an average concentration at or below 0.1 mg/m3. If the mine exceeds the 0.1 mg/m3 respirable quartz dust concentration, then the applicable respirable dust standard is reduced, calculated as 10 divided by the percent quartz present [2]. Respirable dust samples collected by U.S. Mine Safety and Health Administration inspectors for the five-year period from 2010 to 2014 found that 5.6% (53 of 943 respirable coal mine dust samples) of the longwall operators on the tailgate side exceeded the coal mine dust standard, and 4.3% (76 of 1768 samples) of the jacksetters exceeded the standard. If silica is present, the reduced standard is implemented, meaning that 11.4% (36 of 316 respirable coal mine samples analyzed for dust) of the jacksetters exceeded the reduced standard. Only 3.8% (18 of 478 samples) of the longwall operators on the tailgate side exceeded the reduced standard [3]. Had the 1.5 mg/m3 standard been in effect during this period, non-compliant samples would have been much higher. For example, over 15% of the samples collected at the tailgate shearer operator occupation exceeded the lower standard."

Jan 1, 2017

By M. Mathiba

High CO2 fluxes associated with reclaimed coal mine spoils pose an environmental hazard where such sites are used for building. CO2 concentrations in excess of 25% have been reported in homes constructed on or down gradient of such spoils. The objective of this study was to investigate the effect of a mitigation trench used at one mine site on CO2 fluxes across the trench using chamber?based trace gas measurement. LI8100 automated CO2 flux system was used to measure CO2 fluxes from 32 sample points located across a deep mitigation trench on June 8 and 9. The maximum recorded fluxes were 7.29 and 8.18 µmol/m2/s, with averages of 4.15 and 5.50 µmol/m2/s, up and down-dip respectively. These preliminary results show CO2 flux is higher up-hill than down-hill at 95% significant level. This work shows that flux measurement can be used to investigate CO2 migration on reclaimed mine land. Further work is necessary to allow geostatistical modeling of the spatial variability of CO2 fluxes over reclaimed coal mine spoils. Knowledge gained would assist mining practitioners and regulators in reclamation planning for envisaged post-mining land uses.

Jan 1, 2010

By B. R. Pothini, H. von Schonfeldt

In underground coal mining many excavated openings have a relatively short projected life span. To ensure safety for men and materials at a minimum cost over the projected operating life, only pillars for overburden support and roof bolts for support of the openings are used extensively. Mining activity constantly changes the geometry of the mine producing load changes on the structural support members of the openings that often induce unstable deformations which can lead to roof falls or pillar failures. The paper describes how simple deformation measurements can be used to design primary and supplementary roof supports and to predict roof falls and possibly pillar bumps. Specifically, bed separations in the roof measured directly with the help of borescopes and calculated from differential convergence data are used to optimize bolt links or support requirements for chemical stabilization of mine roofs. Roof falls are predicted on the basis of admissible values for cumulative convergence between roof and floor, convergence rate, and the change of the rate of convergence. The pillar extraction operations convergence anomalies detected from contouring identify bump prone pillars, while convergence and pillar dilation determine the yield zone in a pillar to verify pillar softening and de-stressing. Manuscript not received in time for publication.

Jan 1, 1983

By Hitch M.

Many mining wastes, especially those from the metal mining industry, have traditionally been treated as a matter of little or no value and in practice a cost burden. Some wastes, due to their reactivity characteristics, have emergent values that go beyond purely economic and into the environmentally beneficial realm. This paper discusses the changing paradigm of mine waste management. Such fundamental parameters such as cut off grade, and strip ratio, are positively impacted by the revaluation of waste rock material. Mine rock waste can now be seen as a commodity of value, similar to the underlying ore being mined and influences the economic performance of suitable projects. This valuable material can be used for industrial purposes including acid neutralization as well as the capture and long-term disposal of anthropogenic carbon dioxide. The Turnagain Nickel project, located in northern British Columbia serves as an example of how waste rock material can become an important matrix for carbon capture and sequestration and can benefit economically from it. By producing material that has emergent economic value as well as carbon capture and sequestration capabilities, the sequestration matrix producer is a beneficiary of new carbon credits that have a market value and is looked upon favourably by regulatory authorities and affected stakeholders.

Jan 1, 2010

By J. T. Winkelmann

The Mineral Park Mine is an open pit copper-molybdenum mine located in northwestern Arizona, approximately twenty miles northwest of Kingman, Arizona. The concentrating facility has been regarded, with the expansion in 2011, as a plant capable of treating fifty thousand short tons of feed per day for the mixture of supergene and hypogene ores available. The grinding circuit consists of two 32? x 14? SAG mills and four 20? x 28? ball mills. As ores became harder with greater depth in the adjacent pit areas, however, the SAG mills became severely throughput limited. The traditional treatment for similar properties is the installation of a recycle pebble crushing circuit. Because the cost of such an installation is quite elevated, and preliminary testing and research was inconclusive regarding the predicted throughput increases, management and technical personnel set out to find another solution to the problem. The result entailed a redesign of SAG lifters/liners and a nearly unique circuit change which was, at best, a difficult step that defied current grinding logic. This paper describes these changes, events leading up to them, and the results.

Feb 23, 2014

By H. Kempton

New methods for remediating metals-contaminated groundwater include in-situ emplacement of highly adsorptive substrates to permanently retard solutes. Substrates are introduced by sequential injection of soluble components that precipitate in the aquifer, forming a permanent high-retardation zone. This method overcomes the factors that limit pump-and-treat remediation; i.e, long-term source loading and slow desorption. Column tests demonstrated efficient substrate emplacement, increasing retardation coefficients of Cr(VI) by 20 and As(V) by 40. Similar effectiveness is expected for other heavy metals. Simulations using a coupled advective-geochemical model accurately matched substrate emplacement and arsenic attenuation, allowing extrapolation to other constituents and larger-scale applications.

Jan 1, 1999