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By Ibezim J. Anazia

Electrothermal production of elemental phosphorous (P4) generates substantial amounts of highly toxic phossy water and sludges. Because of their high phosphorous content and lack of reliable processing technology, large tonnages of these hazardous wastes have accumulated from current and past operations. To date, the sludges are stored in ponds or above ground in special containment vessels at various locations around the country. Two samples of electric furnace phosphorous sludge obtained from the Tennessee Valley Authority (TVA) in Muscle Shoals, Alabama and FMC Corporation in Pocatello, Idaho were investigated using physical separation techniques to recover the elemental phosphorous in the sludge and to render the residual material non-hazardous. The techniques tested include sizing, froth flotation and dispersed air oxidation. Flotation and sizing produced concentrates containing 69 -90% P4 with a recovery in the range of 60 -87%. Dispersed air oxidation of the fines and tailing products was effective in removal of an additional 10 -15% of the P4 in the sludge.

Jan 1, 1991

By W. D. Bachman

A study has been made of wet, autogenous grinding of disseminated copper ores, including testing of a large number of samples from Kennecott Copper Corporation's Chino mine. The efficiency with which the various samples could be ground was found to vary over an extremely wide range, even among samples taken from different locations within the same ore body. These variations in grindability can be qualitatively correlated with the composition of the rock and the fracturing and alteration that had occurred. Because of the large-scale non-homogeneity of disseminated copper ore bodies, extensive and careful testing of autogenous grinding is needed. An accurate correlation of the grinding data from various samples with the geology of the ore body and with mining plans will indicate if variations in grinding mill throughput can be avoided in practice by mixing or blending of mill feed and if, therefore, autogenous grinding can be applied successfully.

Jan 1, 1970

By Legett Garrett

Texas Utilities Generating Company (TUGCo) surface mines lignite for use as a boiler fuel at mine mouth generation stations. Currently, the annual lignite production requirement of approximately 28 million tons necessitates mining across approximately 1,600 surface acres each year. The mining operations, located in Freestone, Panola, Titus, and Hopkins counties, Texas, have drastically disturbed some 13,000 surface acres to depths of up to 110 feet since initial startup in 1971. The TUGCo mining philosophy, a commitment made prior to initiation of mining operations and prior to any mining regulations, includes a return of mined-out land to private ownership in the most useful state possible. In the areas of TUGCo operations, the local economies are based upon agricultural production. Historic land use surveys have typically shown a trend from row crop production to pastureland for cattle production. During the 1960?s, the percentage of acreage devoted to row crop production approached zero with respect to the total acreage devoted to agriculture. TUGCo reclamation operations have therefore emphasized restoration of land to a state that is favorable to cattle production

Jan 1, 1982

By E. A. Wieselmann

In 1970 Texasgulf (Australia) introduced natural gamma radiation logging of drill holes for exploration in the Hamersley Iron Province of Western Australia. Drill hole logs have allowed positive stratigraphic and structural correlations within complexly folded secondary hematite ore deposits and between individual iron ore deposits separated by distances in excess of seventy-five miles. A Neltronics model KPD logging system and gamma-ray sonde are being used to measure the natural gamma radiation of the enriched Brockman and Marra Mamba banded iron formations. The parent banded iron formations are composed of thick, chemically precipitated iron oxide, chert, iron silicate, and carbonate with thin intro-formational clastic horizons. These clastic horizons give a greater natural gamma radiation than the banded iron horizon, and each clastic horizon has a characteristic radiation profile related to its composition and thickness. Because the natural gamma-radiation profile is unchanged during secondary enrichment of the iron formation, the present stratigraphic position of each drill hole can be established and complex folding can be accurately traced in the sub-surface. Gamma ray logging of percussion drill holes has made feasible a significant reduction in diamond core drilling without loss of accuracy. At the same time, it has provided a means of rapid evaluation of complexly folded iron ore deposits.

Jan 1, 1975

By Bill A. Hancock

In Situ leaching for the recovery of uranium from low grade sandstone deposits is one of the newest technological advances in the mineral industry. It is rapidly developing into a commercially feasible mining system which has economic, environmental, and social advantages over conventional mining systems. Because of the current uranium shortage, development of In Situ leaching into a sophisticated system has gained new impetus. In Situ leaching will become an important mining technique in the future, which will greatly help to supply uranium for our nation's energy heeds. In this paper, I will be giving an overview of the merits of the system, as well as the technology, problems, and research in solution mining of uranium.

Jan 1, 1977

By Nicholas Chlumecky

A practical method is described for determining or checking whether underground supports such as props, posts and mechanized longwall supports have bearing areas of proper size in relation to the type of ground or floor strata on which they are standing, It is felt that this information provides an approach to eliminate, as much as possible, a potential grave source of error during the selection of roof supports. This would also affect the choice of costly mechanized longwall equipment where it is possible that the size of the bearing area is not as carefully determined as, for instance, the design strength of structural components.

Jan 1, 1967

By David A. Summers

Historically, the presence of methane has been a problem, mainly in and around the working areas of active coal mines, and only in these area has drainage been considered. Drainage, where practical, has been achieved through the drilling of holes forward into the coal and the surrounding strata from the working area. These holes generally have been short in length, although where methane drain- age operations around a longwall face have been undertaken, the holes have had to be longer in order to adequately drain from the center of the face into the access gate roads. In recent years, attempts have been made to degasify the coal seams in advance of mining, without disruption of the mining cycle. This is done by drilling much longer horizontal holes through the coal in advance of the working area. Under the aegis of the Federal Government, methods have also been developed for draining seams of coal of their methane content in advance of mining, but from shafts sunk from the surface, without using the active area of the mine as the location for the drill holes.

Jan 1, 1979

By William F. Abercrombie

The role of the laboratory is described in relation to the prospecting and exploration of kaolin clays. Test methods used to evaluate crude ore samples of kaolin clay for commercial consideration are reviewed. A background of the kaolin mineral and known means of prospecting this mineral are presented. Common analytical methods are discussed with special emphasis on those in use today.

Jan 1, 1982

By G. F. Joklik

Although the mineral shortages of twelve to eighteen months ago have given way to oversupply, their memory lingers on. These problems were man-made: booming demand throughout the industrial world, political and industrial unrest and the oil embargo all contributed. But in the minds of many, the shortages conjured up visions of the depletion of the world's mineral resources, a disaster that could be staved off only by drastic curbs on consumption and therefore, curbs on economic growth. A little historical research shows that fears such as this are not inventions of the 1970's. A hundred years ago, for example, the imminent exhaustion of the world's coal supplies was being predicted in Great Britain. The English economist, John Stuart Mill, who was usually more perceptive, wrote a few years earlier that "it is only in the backward countries of the world that increased production is still an important object". And later there was Franklin Roosevelt who said in 1932, "Our industrial plant is built; the problem just now is whether under existing conditions, it is not overbuilt". His concern, in other words, was not with the discovery and exploitation of new natural resources, but with the administration of known resources and with seeking foreign markets for surplus production. In light of copper prices at the time -- just under 6¢ a pound -- that was understandable. These instances illustrate how, throughout the world's industrial history, concern about surpluses of raw materials has alternated with alarm about the adequacy of supplies and with calls for restricting growth.

Jan 1, 1975

By Richard S. Klein

Frozen coal creates severe handling problems. Utilities require uninterrupted supplies of coal to meet their increasing coal consumption rates. Difficulties incurred due to frozen coal result in more costly downtime for the utilities. Air cannons, vibratory hammers and thaw sheds are examples of mechanical devices used to break, crack or thaw frozen coal. Recently chemical treatments have been developed as preventive measures. The freezing of coal depends upon a number of factors, of which one of the most significant is surface moisture. The more there is, the larger the frozen coal problem. Slide 1 depicts a graph of frozen coal compressive strength as a function of surface moisture. Below a certain minimum value the coal will not freeze. Above this point, compressive strength is essentially a linear function of moisture over the range practically encountered. By surface moisture is meant the free moisture on coal having a normal vapor pressure as opposed to capillary moisture or inherent moisture. In addition to the straightforward freezing of coal surface moisture binding particulates together, frost formation occurs due to temperature gradients which develop in rail-cars and stockpiles .

Jan 1, 1980

By A. J. Naldrett

Over the past six or seven years important new ideas have been developed concerning the origin of nickel sulfide deposits. To a large extent these have been stimulated by the major nickel discoveries of the Eastern Goldfields area of Western Australia (Woodall and Travis, 1969; Ewers and Hudson, 1972). Prior to these finds, the most important nickel camps were regarded as being associated exclusively with intrusive rocks such as the Nickel Irruptive at Sudbury or the intrusive peridotites at Thompson, rocks that were thought to have no close association with volcanism. Study of the Australian discoveries, coupled with work in South Africa (Viljoen and Viljoen, 1969) and Canada (Naldrett and Mason, 1968; Pyke, Naldrett and Eckstrand, 1973), has shown that volcanic rocks with true ultramafic compositions and extrusion temperatures of 1400 to 1600°C were a common feature during the Archean. Under certain circumstances economic concentrations of nickel sulfides have formed from these rocks, either settling to the base of their associated flows or accumulating in shallow intrusive feeders to the flows. The aim of this article is to show how these ultramafic rocks can be recognized, how the nickel deposits, if present, are likely to occur within them, and what special features characterize ore-bearing examples of the rocks.

Jan 1, 1975

By K. L. Wiley

In-situ leaching, initiated in 1986 at San manual, was economically developed in 1989. The primary reason for this lag time between startup and viable production was the time required for technical development. The technical development pursued comprised detailed design, development, and implementation of in-situ well construction methods, formulation of suitable well pattern arrays, and the development of extensive hydrogeologic and geochemical knowledge of the mineral deposit. Since 1989, the in-situ leaching program has become a viable and cost effective method to extract copper from the supergene mineralized zone of the San Manuel deposit. The in-situ leaching methods that are currently utilized have been progressively expanded and continually developed and will became the cornerstone of copper production from the San Manuel oxide mineral deposit. This paper presents an overview of the supergene hydrogeology, current design techniques, drilling methods and well completion, pump determination and setting, solution management, and future plans for the increased extraction of copper by in-situ leaching methods at the San Manuel mine.

Jan 1, 1993

By Erwin Riyanto, Roy William, Karl Llewellyn

The Deep Mill Level Zone (DMLZ) mine is currently one of the deepest block cave mines in the world. The rock mass is heavily veined with little to no joints and faults are usually healed cohesive structures leading to difficult cave mining conditions. The caving process is improved if the rock mass contains fractures with sufficient density that it will cave by gravity as undercutting progresses. Hydraulic fracturing (HF) has been used to create fractures around the cave to improve mining. A seismic monitoring system has been used in DMLZ since the start of mining. Therefore, the seismic activities before, during and after HF can be monitored. Shear wave splitting is a process used to study the impacts of HF on the rock mass. This process involves the measurement of travel times from splitting shear waves after seismic events and using this to define the anisotropy within the rock mass and subsequently fracture density. This paper sets out the methodology for carrying out the interpretation of the shear wave splitting process using seismic data from the fracked cave crown and abutments along with an overview of the benefits to cave mining as result.

Apr 26, 2022

By H Vigil, G. Peach

Long tunnels with only one access shaft pose many program problems for logistics, combine these with the requirement to drive directly out under the seabed for 10.2 km, and the program issues become even more challenging. The Musaimeer outfall tunnel was one such tunnel and to meet and eventually improve on the planned completion date required a complex and extensive management of all tunnel logistics required to support consistent tunneling for a two-year period. This technical paper will discuss the management issues and solutions implemented to meet the challenges of the Outfall tunnel construction.

Dec 1, 2022

By Horry Parker Jr, Jason Gillespie, Justin Kolster, Stephen O’Connell

Construction of the 5,932-ft Reedy River Basin Sewer Tunnel in Greenville, SC was marked by a critical transition from drill-and-blast mining in mixed-face conditions to TBM excavation with limited rock coverage. In this paper, we discuss the geological, geotechnical, and risk management considerations for transitioning to TBM operations in variably weathered gneissic bedrock. After construction of an unexpected 230-ft starter tunnel due to differing site conditions, the 11-ft diameter TBM was successfully launched in December 2019 without significant ground support issues. This project highlights the effectiveness of extensive rock probing to fully characterize bedrock topography prior to the TBM launch.

Jun 13, 2021

By Jürg Künzle

Underground construction is a matter of dealing with the inherent uncertainty of subsurface geology. If the encountered conditions are less favorable than the expected ones, the execution of excavation, support, ground treatment or lining works is likely to require more or different efforts than anticipated, thereby delaying the works and increasing the costs. The 2019 first edition of the FIDIC Emerald Book model contract (FEB) addresses many of the issues to which underground works give rise, including those related to differing site conditions (DSC). This paper examines how under the FEB disputes arising from or in connection with DSC could or should be avoided.

Jun 13, 2021

By Theodore Feldsher, Seung Han Kim, Mourad Attalla, John Roadifer, Chu-Chieh Jay Lin

Lifelines in seismic regions of the world seldom can escape crossing active faults. Cities in California have been mitigating this risk by constructing improved fault crossings. This paper discusses the analyses and design of the lining for a tunnel carrying a water conveyance pipeline through a fault that can potentially displace during a major earthquake event. The paper presents expected fault displacement, fault width and orientation respective to the tunnel, characterization of the ground surrounding the tunnel and its interaction with the lining, and performance required of the lining. Several other fault crossings will also be presented and discussed

Dec 1, 2022

By Elimame Elaloui, Kais Elghniji, Constantin Virlan, Aurel Pui, Chaima Ouled Amor

Separation and identification of minerals composing the Tunisian silica sands have been conducted by acid etching and hot filtration/sedimentation (HFS) without affecting the quartz component. It was found that the hot acid etching process is an effective method to separate quartz and clay minerals in the silica sand. The SEM micrographs of the silica sand show rough surface and some cracks with irregular shapes. The surface becomes clean and smooth after acid etching process. After chemical dissolution, the clay minerals were recovered by hot filtration following by sedimentation at low temperature. FT-IR, EDS maps, and secondary electron (SE) analyses of separated clay minerals reveal the presence of Fe2O3, montmorillonite, and kaolinite minerals. The LIBS analysis of clay minerals shows the presence of Al, Fe, Ca, Al, and Mg. The sequential etching process can be introduced in the purification methods as an effective way to separate quartz from clay minerals.

Jul 29, 2020

By A. A. Zatout, G. H. Sedahmed, T. M. Zewail, M. H. Abdel-Aziz, B. S. Ibrahim, E-S. Z. El-Ashtoukhy

In this work, the possibility of intensifying the cementation process in stirred vessels was studied by using the perforated baffles as turbulence promoters; the cementation reaction of Cu+2 on Zn was selected as a model. Zn was used in the form of a sheet lining the inner wall of an agitated vessel. Parameters considered are initial concentration of Cu+2, solution temperature, impeller rotation speed, and impeller geometry. Within the present range of parameters studied, the rate of cementation was found to increase with increasing initial concentration of Cu+2, solution temperature, and impeller rotation speed. At the same rotational speed, a flat turbine gave a higher rate of cementation than a 45° pitched turbine. The present suggested that baffles’ geometry gave superior performance in terms of mass transfer of copper cementation compared to the conventional baffle geometry. All parameters that affect the rate of cementation were correlated in the form of dimensionless equations suitable for the design and performance prediction of the agitated vessel. Potential applications of the obtained results in the field of hydrometallurgical processes and wastewater treatment were discussed.

Jan 12, 2021

By P. Samanta, Mohammed N. Azad, Gustad F. Taraporewalla, A. K. Mukherjee, Abhay S. Patra, D. Sachinraj

Beneficiation of coal is a water intensive process, and the water is recovered in downstream operations in the high rate thickener (HRT) and vacuum belt filtration (VBF). Clean coal particles entering the HRT have an inherent tendency to enter the overflow because they are extremely fine and hydrophobic. Hence, flocculants (polymers) are used to floc the ultrafine particles so that they settle and enter the underflow. Ultrafine coal particles (−37 μ), which are highly hydrophobic, if present in the stream, will not be efficiently captured by using flocculants alone. This is observed in the normal plant operation at one of the beneficiation plants in the Jharia region, Jharkhand, India. Approximately 6–7% of the feed to the HRT enters the over flow (supernatant water). Hence, this amount of clean coal particles is not recovered and account for production losses. A comprehensive settling and dewatering test work was conducted with clean coal slurry using several commercially available reagents. Studies were also done on different combinations of reagents, including coagulants and surfactants along with flocculants, to improve the settling behavior of the coal particles. The reagents were assessed based on their performance with respect to settling rates, overflow water clarity, and compaction of the underflow solids. Emphasis was given to the ability of the reagents in compacting thickener underflow to higher densities so that maximum water could be recovered from the thickener. Pretreatment of highly hydrophobic coal slurry with a combination of coagulant and surfactant followed by flocculation showed very good settling characteristics with clear overflow.

Sep 30, 2021