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By Ernest L. Bradley

A positive pressure ventilation system, augmented by a dewatering well curtain and underground longhole drilling, provides effective ventilation and radon control at EXXON Minerals Company's Highland Underground Mine in the Southern Powder River Basin of Wyoming. Testing different types of bulkheads, sealants, and bleeder systems has led to improvements in the basic ventilation system. Continued testing of new or different materials and equipment is expected to lead to further improvement in the ventilation program. Effective training of both miners and supervisors is essential to maintaining and improving ventilation techniques. This paper addresses the ongoing ventilation program and experience to date at the Highland Uranium Mine.

Jan 1, 1979

By Ihsan Berk Tulu, Mustafa Can Suner

The synthetic rock mass (SRM) approach is a relatively new method to study the mechanical behavior of rock masses. Recently, an SRM approach was established to estimate pillar strength from laboratory scale to in-situ dimension using the two-dimensional Universal Distinct Element Code (UDEC). In this study, the developed methodology is applied to the S-Pillar database to estimate pillar strength and failure mechanisms as a function of width-to-height ratio of the pillars. First, stone mine rocks are categorized into three as low-, medium-, and high-strength according to their uniaxial compressive strength (UCS). Later, laboratory-scale intact rocks are scaled-up to the average in-situ pillar dimensions by explicitly considering the naturally existing joint sets. It is found that the strength of the pillars with low-UCS are overestimated when compared to pillars with high-UCS. This observation is attributed to the high joint density of the pillars with high-UCS. After obtaining in-situ pillar strength, the width-to-height ratios of the pillar models varied from 0.5 to 2.0 to gain a robust understanding of pillar mechanical behavior. Tensile failure is found to govern the pillar behavior with the width-to-height ratio of 0.5 while the combination of tensile failure in rib elements and shear failure in the core

By J. P. Morgan

The Vesta Preparation Plant of the Jones & Laughlin Steel Corporation is located on the Monongahela River, eight miles south of Brownsville, Pennsylvania. This plant is capable of cleaning 2400 NT/hr of a mixture of Pittsburgh seam high volatile coals from the Vesta and Shannopin mines to produce a metallurgical coal of 6.75% ash and a steam coal containing 14% ash. Heavy media vessels are utilized to upgrade the coarse coal while launders and tables. handle the -1/4" fraction of the raw coal feed. Cleaned -coal goes to boot classifiers where the +48 mesh material settles and is removed by bucket elevators. This 1/4 x 48 mesh material is then sent to centrifugal driers for dewatering. As designed, the minus 48 mesh fraction overflows the boot as a 7 to 8% solids slurry and is recovered by cyclones and a thickener and dewatered by filtration. The-products of the heavy media circuit, the launder-table-boot-drier circuit and the cyclone-thickener-filter circuit are combined to constitute the shipped metallurgical coal. This Vesta-Shannopin mix is combined at J&L's Pittsburgh and Aliquippa Works with purchased low and medium volatile coals for the production of metallurgical coke.

Jan 1, 1962

By Jiachen Wang, Nan Wang, Yang Li

The energy structure and consumption ratio in China determine the practical demand for the collaborative mining of coal and co-associated resources. The multi-layer mining of coal, uranium, coalbed methane, and oil and gas co-associated resources, represented by the Ordos Basin, Junggar Basin, and Tarim Basin, faces numerous challenges. Additionally, coal has been found to coexist with various mineral resources in 33 coal-bearing basins worldwide. The scientific issues related to the multi-layer development of coal related co-associated resources urgently need to be addressed. This paper discusses the unique challenges and potential solutions in the multi-layer development of coal-related co-associated resources. The challenges include large extraction space, high mining intensity, intense overburden movement, rapid surface subsidence, and severe overburden damage due to repeated mining disturbances. Proposed solutions include the establishment of a correlation mechanism between multi-layer mining and the carrying capacity of the overburden environment, analysis of the impact characteristics of multiple field couplings, and exploration of their superposition evolution laws. The paper also proposes the development of a comprehensive evaluation and prediction system for overburden environmental capacity loss, a global sensitivity analysis model for overburden environmental capacity, and an intelligent identification and early warning system based on multi-source information fusion. These solutions aim to achieve scientific and precise mining with minimal overburden environmental capacity loss. And the multi-layer development of coal-related co-associated resources is a complex task that requires a multidisciplinary approach and innovative solutions, and further research is needed to validate these strategies and explore new methods and technologies for efficient and sustainable extraction.

Jun 25, 2024

By G. L. Alston

Rigid urethane foam can be used effectively for improving mine air conditioning systems by reducing heat and moisture transfer from mine rock to ventilating air and from mine rock to ventilation ducts, for erecting mine ventilation stoppings and overcasts, for sealings around door frames and bulkheads to prevent air leakage, for preventing spalling and sloughing of roof and rib and for erecting fire-resistant powder magazines and transformer or compression stations. Rigid urethane foam is a tough, cellular material, made by nixing diisocyanate and polyether polyol resin in accurate proportions through an applicator system, then the two chemicals react, the mixture expands thirty times its original volume with 85 to 95 percent closed cells. Within seconds, the mixture solidifies and takes a preset which will adhere to overhead or vertical surfaces. It will adhere to brattice cloth, steel, wood, concrete and rock, Excessive wetness will reduce the adherence, but in such cases adherence can be improved by preliminary application of an absorbent dust such as cement.

Jan 1, 1963

By M. Misra

A sample of thorium-contaminated soil from Kirtland Air Force Base (AFB) was subjected to froth flotation for removing thorium contaminants. A series of flotation tests were conducted to screen and evaluate the reagents. Among the collectors used, sodium oleate exhibited to show the promising results. Preliminary tests showed that a concentrate having activity as high as 5300 pCi/g can be obtained from the contaminated feed soil having activity 800 pCi/g. The volume reduction obtained was 89% and the activity recovery in the concentrate was 68%. The paper discusses the physico-chemical characterization data and the potential physical separation decontamination schemes for the thorium contaminated soils.

Jan 1, 1996

By A. J. Lynch, M. J. Lees

Introduction The design of wet grinding circuits may vary considerably according to the duty which is to be performed. Grinding machines which are commonly used in these circuits are rod mills, ball mills, autoge¬nous mills, and pebble mills while size separation machines commonly used are vibrating and wedge-wire screens, hydrocyclones, and rake classifiers. In some circuits, such as those producing feed to cement kilns, all the ore entering the circuit is discharged in a single product stream. In others, such as those operating on magnetite-taconite ores, the feed entering the circuit leaves in two or more streams. Grinding circuits in flotation plants normally include sections in which either the concentrate or the tailings from the primary flotation circuit is reground and these additional sections should be regarded as an inte¬gral part of the grinding circuit. A typical circuit is shown in Fig. 18. Problems in achieving maximum efficiency may occur at three stages: 1) At the design stage when the optimum size reduction flow¬sheet must be selected with respect to the types, numbers, and sizes of processing units. 2) At the operating stage when the correct selection of values must be made for those variables which may be altered while the circuit is off-line but which are constant while the circuit is on-line, for instance the vortex finder diameter of the cyclones. 3) Under conditions of continuous operation when changes in the circuit feed or in the mechanical operation of the circuit may cause undesirable changes in the circuit product. The first two prob¬lems are concerned with optimization, that is, with making the best choice from many possibilities, and the last with control. Optimization Problems. The main purpose of a wet grinding circuit is to produce particles with a sizing distribution which will ensure optimum performance of the later chemical reaction or physical concentration circuits, because it is on the efficiency of these later circuits that the economics of the total mineral treatment process depend. The size distribution of the product from a grinding circuit may be affected by many variables, some concerned with the arrange¬ment and operation of the machines and some concerned with the ore characteristics, and it is important that these should be recognized in the design and operation of the circuit. For instance, in a simple ball mill-cyclone circuit the variables which affect the product size even for constant feed characteristics are shown in Fig. 19. In addition, the rate, size, hardness, and mineralogical composition of the feed will affect the performance of the circuit and the product size. When the circuit contains more than one mill, both the number of choices available and the complexity of the problem are increased consider¬ably. Consequently, one type of problem which is to be solved if an optimum product is to be obtained from an existing grinding circuit is that of circuit design, and this includes arrangement of processing units and selection of those operating conditions which cannot be altered when the circuit is operating, such as mill speed and cyclone inlet and outlet dimensions. The other major problem in optimization is encountered at the design stage when a choice must be made about the type, number, and size of processing units. For instance, for a typical high-capacity size reduction operation, should two circuits each containing one rod mill and two ball mills or three circuits each containing one rod mill and one ball mill be used? Alternatively, should ball mills only be used and if so, how many, what size, and what arrangement?

Jan 1, 1985

By G. M. Li

It is shown that seriously preoxidized arsenopyrite can adsorb a large amount of copper ions as unoxidized one, but without, release of corresponding amount of Fe ions; seriously preoxidized pyrite cannot adsorb copper ions, but with release of a large amount of Fe ions. However, if the minerals are rapidly oxidized with potassium permanganate solution, both arsenopyrite and especially pyrite can adsorb a large amount of copper ions, but still without release of corresponding amount, of Fe ions. Cu adsorption (if there is any) on both oxidized arsenopyrite and pyrite is not based on the Cu-Fe exchange mechanism.

Jan 1, 1991

By A. E. Petersen

The United States Bureau of Mines conducted research on high-intensity magnetic separation methods for upgrading tantalum concentrates from Alabama. Process flow sheets were studied to maximize tin removal and minimize tantalum loss. Using laboratory-scale equipment, concentrates were produced which contained over 65% combined Ta2O5-Nb2O5. Up to 78% of the tin was recovered as a byproduct, containing about 70% SnO2. Only 1 to 5% of the tantalum reported with the tin byproduct. The producer subsequently incorporated high-intensity magnetic separation into its process flow sheet to provide concentrates for the National Defense Stockpile.

Jan 1, 1993

By Edgar A. Scholz

The purpose of this paper is to make a comparative cost analysis of domestic and foreign exploration projects which developed into mines during the 1960-1974 time period. A total of 18 mining companies, American and Canadian, were approached to solicit cost data on domestic and foreign exploration projects which developed into mines. Only 20 percent of the companies to which questionnaires were sent made data available. Several companies answered negatively, informing us that they would have difficulty in attempting to sort our costs. Some companies were usable to release cost details. It is comforting, however, to realize that some of the non-contributing companies expressed eagerness to hear the findings of this paper. Inasmuch as the data available on exploration expenditures is, in some cases, somewhat uncertain and that no two mining companies follow the same system of cost allocations, the results obtained in this analysis should he interpreted as trends of a general character.

Jan 1, 1976

By A. W. Jenike

Mine backfilling is a desirable method for the disposal of retorted oil shale. Hydraulic, mechanical and pneuna.cic transport and stowing methods were investigated, and the mechanical transport and stowing method using conveyors was selected as the most promising system. Transport of retorted oil shale at the rate of 3000 cons per hour (2700 t(h) to the backfill level, situated about: 2000 feet (610 m) below surface, with skips or conveyors is uneconomic. Hence, borehole transport utilizing gravity flow was investigated. This paper describes the theory of flow, flow properties of retorted oil shale, and the design of a borehole and hopper system.

Jan 1, 1978

By G. P. Hand

The graphite industry as a whole has gone through many changes over the years. Most of the graphite used in major applications since the turn of the century were basic natural or electrode by-product synthetic materials, processed using simple crushing, screening, or grinding techniques. In the mid 1970's new thermal technology was developed which changed the face of the .graphite industry, and opened up a panacea of new products and capabilities. Materials produced through this new technology have helped revolutionize new products and processes in industries including automotive, batteries, fuel cells, electronics, iron, lubricants and steel. This paper outlines the continued improvements in those industries as well as the as well as the outlook for new technology in this rapidly changing area.

Jan 1, 1997

By Gian-P. Lozej, Ross Y. Black, Sami S. Maddah

The Zabirah bauxite is a Cretaceous paleolaterite exposed by postTertiary uplift and erosion of the Phanerozoic sequence. The laterite profile, which is preserved in situ, occupies a prominent angular unconformity over a sequence of sandstones, siltstones and mudstones ranging from Late Triassic to Early Cretaceous in age, and is overlain by a Late Cretaceous terrigenous and carbonate package. The profile is known to be preserved over an area of 250 sq km and at depths below the present surface of up to 80 m. The bauxite layer is hard, compact and predominantly pisolitic, with a variety of subordinate, superimposed textures resulting from post-formation alteration. The bauxite minerals are boehmite and gibbsite. Boehmite generally predominates, and the boehmite:gibbsite ratio averages 2:1, with a marked tendency for the proportion of boehmite to increase down the profile. Kaolinite, a major constituent of the profile, is concentrated in two zones, one above and one below the pisolitic bauxite layer. Iron content is variable and bears a direct relationship to parent-rock lithology. Genesis and preservation of the bauxite are due to the favourable coincidence of a number of geological controls of which the most significant are the local structural and sedimentary regimes, the lithology and chemistry of the parent rocks, and the Cretaceous paleogeography of the region.

Jan 1, 1984

By W. M. Ma, W. L. Zhong, Syd S. Peng

In a longwall section that consisted of 7 longwall panels, there were two high pressure gas transmission pipelines across the panels burying from 3 to 10 ft. below the surface. One pipeline was 20 in. in diameter while the other was 24 in. in diameter. In order to investigate the stress conditions sustained by the pipelines during underground longwall mining, strain gages were mounted on the pipelines above panel #3, #4, and #5. Survey monuments were also installed along but near the pipelines. This paper presents a subsidence prediction method and the preliminary results of the pipelines' stress conditions as affected by underground longwall mining.

Jan 1, 1986

By Gus H. Goudarzi

The apatite deposits in east-central Bahia, Brazil, are about 50 km east of Serra do Jacobina, between lat. 11° and 12° S. and long. 39°40' and 40° W. Apatite was found and examined at 15 localities in a mineralized belt that strikes about N.25° - 30 W. over a distance of about 100 km, but the size of the deposits has not yet been determined. Rocks of the region consist of a sequence of Precambrian migmatites and quartz feldspar paragneisses containing units of pyroxene-rich rocks, lenses of sillimanite-bearing quartzite, amphibolite zones, and calc-silicate marble lenses. Pegmatites and granites of probable anatectic origin (anatexite) are abundant. Faults are numerous. Clastic sediments of Tertiary and Quaternary ages cover most of the area; thus, outcrops of the Precambrian rocks are sparse. Trenches and pits have exposed mineralized zones as much as 10 m wide at some localities within the region. A layer of apatite at least 1 ½ m thick is exposed in a trench at Lagoa do Mel. At Rio do Peixe, vertical shafts have penetrated a mineralized zone, to a depth of as much as 13 m, of which about 25 percent is apatite. Apatite is massive or forms minute crystals, stringers, and disseminated grains in alkalic host rocks. At Apolinario, euhedral crystals of apatite are as much as 50 cm long and 30 cm in diameter. Associated minerals include vermiculite, biotite, scapolite, opal, chalcedony, epidote, montmorillonite, chlorite, kaolinite, sericite, magnetite, and limonite. Apatite is everywhere intimately associated with pyroxene-rich rocks, alkalic syenite pegmatites, and alkalic granite pegmatites. At Panelas-Retiro, apatite is associated with pegmatites, crystalline calcite (vein calcite), vermiculite, and pyroxene-bearing rocks. Analyses of samples show that the apatite is radioactive and rare-earth-bearing. Traces of vanadium and titanium were detected by spectroscopic analysis. The apatite was probably derived from phosphatic zones in the original Precambrian sedimentary rocks and has been crystallized and some mobilized by high-temperature regional metamorphism (higher amphibolite facies) into veins, pegmatites, and along certain preferred beds and fractures. Radiometric and geophysical surveys, in addition to conventional geological investigations, are planned to further investigate the nature and economic potential of the deposits.

Jan 1, 1972

By B. Campbell

This paper will detail the successful construction methods of a 20- foot diameter wet well shaft, approximately 180 feet deep in overall depth and 150-feet below the water table, adjacent to Lake Nacimiento, in San Luis Obispo County, California. In addition to this, highlights will include the selection process in determining the most economical support of excavation, while minimizing risk of large water inflows as indicated in the Owner?s Geotechnical Baseline Report (GBR).

Jan 1, 2010

Large variations of coal seam thickness and roof conditions are associated with the occurrence of mine floor undulation at Shoal Creek Mine, operated by Drummond Company, Inc.. Ground control problems, such as roof falls and face failures along with extremely high shield pressure and rapid face convergence, are often reported at the longwall face when these undulations exist. This greatly increases equipment downtime and causes production delays. As a result. a comprehensive study of mine geology including roof conditions and longwall performance were conducted in the mine. With the help of continuous full-face shield pressure monitoring using the Longwall Strata Control and Maintenance System (LoSCoMS), a large data base of shield pressure with various roof conditions has been established. This enables the mine operators to accurately evaluate the roof behavior and shield performance and to take the appropriate operational steps at the face to reduce the number of downtime and face failures. This paper summarizes all works and findings from the study including detailed roof geology and its effect on longwall performance.

Jan 1, 1998

By Richard B. Berg

Until its closure in 1999, the Antler was North America's only active chlorite mine. The mine is located 25 miles (40 km) southeast of Butte in the Silver Star district - an old Montana gold mining district. In 1975, two prospectors searching for talc re-examined a prospect showing a green, fine-grained mineral resembling talc. Following identification and testing of this magnesian chlorite (variety clinochlore), Cyprus Industrial Minerals began processing ore from this deposit in 1976. Chlorite veins ranging up to 30 feet (9 m) in thickness were formed by essentially complete replacement of Precambrian (Archean?) quartzofeldspathic gneiss. Chlorite replacement was controlled by near- vertical faults. These chlorite veins, typically surrounded by envelopes of sericitic alteration, were formed by the introduction of magnesium-rich hydrothermal fluids, probably related to the Proterozoic talc-forming event in southwestern Montana. Luzenac America, Inc. acquired Cyprus' talc operations in 1992, and continued to mine this deposit until the ore body was mined out in March 1999, and the mine was reclaimed. Total sorted ore production from this deposit is about 250,000 short tons (st) (227,000 metric tons [mt]). Chlorite from this deposit was primarily used in ceramic and paint applications.

Jan 1, 2001

By Richard I. Grass

The White Pine Mine is located 4- 1 /2 miles south of Lake Superior in the western part of Michigan's Upper Peninsula. The orebody occurs in tabular, gently dipping Keweenawan sediments. GEOLOGY The orebody outcrops beneath 30-50 feet of Pleistocene clays and dips to the east and northeast to a depth of 3, 000 feet in five miles. It lies midway between the Porcupine Mountains and the Bergland Hills, both of which are steeply dipping felsite and coarse porphyry intrusives, extrusives and sediments (Figures 1 and 2). The orebody sediments were deposited in the Keweenawan basin during mid- and upper Keweenawan times. Mineralization occurs in the basal 20 to 25 feet of the Nonesuch formation, which is made up primarily of laminated siltstone s. Native copper, chalcocite, and silver are the ore minerals. The ore is mined by trackless room-and-pillar methods.

Jan 1, 1967

By L. R. Moore

The World Health Organization (WHO) considers contamination from oxyanions, such as selenium and arsenic, a global concern. While their elemental forms are toxic, the aqueous oxyanions are more so. These aqueous forms, which exist at a higher oxidation state, are the most common forms released during mining processes. Many technologies are capable of meeting the governmental discharge criteria for oxyanionic contaminants, but may possess limitations due to redox chemistry as well as the water matrices. An innovative technology was developed that can successfully reduce such aqueous forms generated during mining processes to a level below the discharge criteria. This paper discusses how an understanding of the sensitivities of this novel adsorbent towards these variations in water matrices and redox chemistry can be used to optimize its application.

Feb 27, 2013