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By Samuel Frimpong

Synthetic fuel is a liquid hydrocarbon fuel synthesized from unconventional resources, such as tar sands, heavy oil, coal, and oil shale. These unconventional resources are immense and will be a major energy source for the 21st Century as the availability of conventional crude oil and natural gas declines. The authors review the available global distributions, production data, research frontiers, and current research organizations involved in tar sands, heavy oil, coal, and oil shale. Tar sands and heavy oil is mainly deposited in Canada, Venezuela, and the United States. Oil shale reserves are found in United States, Jordan, China and Australia. Coal occurs in United States, Russia, China, Canada, and Australia. Major research and development efforts are focused on reserves identification, transportation technologies, production cost modeling, bitumen extraction process improvements, coal liquefaction technologies, elimination of pollutants, greenhouse gases, and safeguarding human health and the environment. This review forms a major source for educating the public about these important energy sources, and the need to develop environmentally sound technologies and policies for their extraction.

May 1, 2007

By J. D. Doherty

That America's great coal deposits eventually will be our principal source of liquid as well as solid fuels is generally accepted. Moreover, the day when synthetic oil from coal will begin to supplement our petroleum supplies does not appear to be far off. The American petroleum industry has not spared effort or expenditure in its attempt to keep pace with the demand for oil, and recent production has exceeded expectations. However, the rapidly rising demand for liquid fuels plus the increasing difficulty of finding and developing the new oil needed even to maintain present production rates make it highly unlikely that oil from domestic wells can fully meet future oil requirements. Therefore, it appears that one or more of the following courses must be followed: 1. Curtail oil consumption. 2. Increase imports. 3. Develop new sources such as synthetic liquid fuels.

Jan 1, 1949

By P. R. Hervey

Quartz is the second most widely used electronic material, with approximately 3,000 tons of single crystals used each year. Virtually all of this material is synthetic; grown with a technique called hydrothermal growth. We will review the basics of hydrothermal growth, the feedstocks for these crystals, and the challenges to improving the growth process. We will also review the processing of these crystals, the markets and applications where they are used, and the global outlook for these markets.

Jan 1, 1999

By B K. Hebblewhite, G Sharrock

The strength and deformation properties of a rock mass are important parameters influencing the design of civil and mining excavations or structures. The mechanical behaviour of jointed rock masses are controlled by the characteristics of discontinuities and the strength of intact rock bridges between discontinuities. To date, analytical, empirical and experimental methods have not captured the key mechanisms controlling the mechanical properties of actual rock masses with non-persistent joints. The emergence of the synthetic rock mass (SRM) in 2007 provides a promising approach for this purpose. In this paper a rock mass with non-persistent joints is analysed with the SRM model based on PFC3D. The influence of joint geometrical parameters on the uniaxial compressive strength (UCS), rock mass deformation modulus (Em) and failure mode is studied. Joint parameters include joint orientation, persistency, spacing and step angle. Prismatic numerical samples with dimensions 300 mm × 150 mm × 50 mm were generated and a sensitivity analysis of each joint parameter on UCS and Em was undertaken. The results show that of the parameters tested, joint orientation has the greatest influence on UCS. Minimum UCS occurs when the angle between the major principal stress and joint surface is approximately 60°. The joint step angle was found to have a significant effect on failure mode and a joint step angle of 90° is the most favourable joint orientation for step-path failure. The importance of joint step angle is highlighted in the discovery of a failure mode bifurcation point at joint step angles of 60° and 90° for joint orientations of 75° and 90°, respectively. For these parameters the failure mode transitions from block rotation to a new failure mode where the coalescence of cracks results in the formation of new small regularised blocks.

Sep 26, 2011

By M. B. Hopkins

FOR years the expression "except rubber, tin, and manganese" has appeared in practically every discussion of the natural resources of the United States. Knowledge that natural rubber is not produced in the United States has now spread from the relatively few who have reason to be interested in the country's basic raw material supplies to all those who ride in automobiles, which means everybody. This "everybody" reads in the daily papers that we have a stock pile of natural rubber and that plenty of synthetic rubber is just around the corner. Statistics as to the United States' rubber requirements and sources of supply are of interest to him only to arrive at an answer to the question : "After taking care of rubber requirements for military purposes, will there be rubber for my automobile and the many other rubber articles I want?" More than 30,000 different rubber articles are manufactured in addition to the tires and tubes which use up about 70 per cent of the rubber supply.

Jan 1, 1942

By I. M. Morsi, S. Z. El-Tawil, O. A. Fouad, K. A. El-Barawy, M. B. Morsi, M. M. Nasr

Upgrading of a low-grade titanium slag (~55% TiO2) with high silica, calcia, magnesia and iron contents has been studied using sulphation roasting technique using SO2/air gas mixture followed by hydrochloric acid leaching. XRD analysis of the sulphated slag reveals the presence of kennedyite (Fe2O3. MgO. 3TiO2), rutile (TiO2), calcium sulphate (CaSO4) and calcium silicate (3CaO.SiO2) phases. The residue after leaching contains mainly kennedyite, rutile phases and free silica with traces of calcium silicate phase. Synthetic rutile that has about 83% TiO2 can be produced at the optimum conditions. Thermodynamic calculations give rational explanations of the obtained results.

Jan 1, 2005

The ERMS Process was developed during four years of testwork by Austpac Gold NL to overcome the severe metallurgical problems of the ilmenite atWestport, in the South Island. These deposits have been known for about one hundred years. They were originally mined for gold, and only later attracted attention as a possible source of titanium minerals.   The resource is of world scale and may exceed 20 million tonnes of contained ilmenite. Similar deposits occur at Barrytown further south and together these areas would constitute an important opportunity for export-oriented mineral development, if a viable beneficiation technology were available. Further processing is essential, as the composition of the ilmenite is well below market specifications.

Jan 1, 1993

By C. G. McLachlan

INTRODUCTION The work described in the following paper was under-taken with a view to determining, if possible, the relative importance of some of the phenomena on which flotation seems to depend, in the hope that, if this information could be obtained, it would be of value in dealing with the problem as a whole. At the outset, brief reference will be made to three papers which had a considerable bearing on the course followed in the present investigation. In 1919, Langmuir, in a paper on 'The Mechanism of the Surface Phenomena of Flotation', showed that mono-molecular films of very great stability could be produced on solid surfaces with oleic acid, but that pure paraffin oil, though spreading readily on a dean dry surface, was easily displaced by water.

Jan 1, 1926

By Donald W. Breck

Zeolites were first recognized as a new group of minerals by Cronstedt with the discovery of stilbite in 1756. The word zeolite was coined from the two Greek words meaning "to boil" and "a stone" because of the loss of water when heated in the mineralogist's blow pipe. (1) In 1845 it was discovered that certain soils have the power of retaining ammonium Salts. (2) These were the first ion exchange experiments. Later it was discovered that it was the hydrated silicates in the soil that produced this phenomenon and several years later a paper was published dealing with the action of dilute salt solutions on silicates which showed that this base exchange principal, which we now call cation exchange, is reversible. The quantitative cation exchange behavior of zeolite minerals, such as chabazite, was studied. As a result any aluminosilicate which exhibited the property of ion exchange was referred to as a "zeolite;" even today the term has been applied to clay minerals as well as synthetic organic ion exchange resins.

Jan 1, 1973

By Donald C. Wotring, Douglas A. Gabriel, Michael G. Vitale

"The Northeast Ohio Regional Sewer District (NEORSD) recently completed the 24-foot diameter Euclid Creek Tunnel using a steel-fiber reinforced concrete segmental lining. During construction HMM, the McNally/Kiewit JV, CSI/Hanson JV, and the NEORSD performed a test program to evaluate replacement of steel fiber with synthetic fiber. A section of synthetic-fiber-reinforced cast-in-situ lining was also placed as part of the permanent works for the starter and tail tunnels. Laboratory and field testing were performed on two complete segmental rings reinforced solely with synthetic fibers. This paper summarizes the testing program, construction, and results of the synthetic-fiber-reinforced CIP lining and concrete segments. INTRODUCTION The principal feature of the Euclid Creek Tunnel (ECT) project is a CSO storage tunnel that is one component of the Northeast Ohio Regional Sewer District’s (NEORSD) Easterly CSO storage and conveyance system. The tunnel, shafts, and appurtenant facilities will be used for the collection and storage of CSOs from the northeastern part of Cleveland, Ohio and subsequent conveyance to the NEORSD’s Easterly Wastewater Treatment Plant for treatment. The ECT project includes five drop shafts that extend as deep as 220 feet below the ground surface. The ECT alignment and shaft locations are shown in Figure 1. Traditionally in northeast Ohio, tunnel excavations were supported with a two-pass system using steel ribs and timber lagging, followed by cast-in-place concrete. Control of rock overbreak proved difficult with large-diameter two-pass operation, and invert degradation led to train derailments. To mitigate these risks, the ECT was supported using one-pass, precast, bolted, gasketed concrete segments reinforced with steel fiber alone. Tunneling operations were very successful and experienced no significant delays or claims. As a result of the positive ECT experience with steel fiber-reinforced segments, Hatch Mott MacDonald, LLC (HMM), McNally/Kiewit (MK) joint venture, CSI/Hanson (CSI/H) joint venture, and the NEORSD performed a test program to evaluate replacement of steel fibers with synthetic fibers in segmental rings. This paper presents the laboratory and field testing program, construction, and results of the synthetic-fiber-reinforced cast-in-place (CIP) lining and concrete segments."

Jan 1, 2016

By Yongfu Yu, Xiaotie Wang, Fuguang Zhang, Liping Che

"Rare Earth water dregs is the drained waste dregs, which contains over 0.2 percent thorium dioxide and about 6-10 percent di-Rare Earth trioxide, which is beyond the standard of draining off that China governments set, so that the Rare Earth water leach dregs must be sacked and laid down in storehouse, which costs lots of money. It is a pity that the RE and thorium compounds very useful elements in industry are discarded. A lot of work must be carried out so that this resource was fully developed.In this paper, four separation techniques of recovery Rare Earth minerals and enrichment thorium element and reduction thorium content of drained dreg for the different test samples of Rare Earth water leach dregs which is radioactive waste dregs got from diverse locus are studied, respectively, and the separation characteristic and the separation process are described, using several combination processes of classification and gravity and flotation separation which were prepared according to the characteristic of test samples and technology. The test results show that the combination processes are the more remarkable separation techniques and the flotation reagents used in test can be applied to utilizing synthetically radioactive waste dregs. Through the combined technique process, three parts of products were obtained, namely, Rare Earth concentrate collected, the thorium product enriched and a large amount of the waste dregs product that can be directly drained and the total quantity is 50%-60%. In order to determine optimum technical condition, the effect factors of separation process were investigated in the test."

Jan 1, 2003

By Stitt P. H

In Australia, the term "heavy mineral deposits" is used to denote sands which contain variable but economic quantities of the minerals rutile, ilmenite and zircon, often with minor amounts of monazite and xenotime as co-products. Australia has been a significant producer of rutile, ilmenite and zircon from such sands for fifty years and has long been the leading producer of rutile and zircon. The industry had its beginnings with the mining of present day beaches in northern NSW in 1934. Early work was small scale and in some cases involved hand winning of naturally concen- trated mineral for direct export. During World War II and immediately after the industry became increasingly mechanised and by the 1970s on the east coast operated between Newcastle, NSW north to Fraser Island in Queensland. Deposits worked included present day beaches, fossil strand lines up to 5 km or more inland from the present coast and aeolian concentrations. In the mid 1950s, operations commenced on the west coast of WA, south of Perth. Western Australian mineral sands tend to be rich in ilmenite as compared to the east coast. However the WA ilmenites are lower in chrome oxide and make a better syn- thetic rutile feedstock.

Jan 1, 1988

Simulation has established itself as an accepted tool for the design and optimization of complex minerals processing plants. This paper addresses the use of simulation as a tool for the design and optimization of carbon-in-pulp and carbon-in-leach (CIP/CIL) plants. The complex, interactive nature of CIP/CIL plants makes detailed experimentation an expensive and time consuming approach to CIP/CIL plant design and/or optimization. This paper discusses a simulation-based software tool that can make the process of CIP/CIL plant design and/or optimization much more cost effective. Many of the issues and problems pertaining to the use of simulation for CIP/CIL design and operation are generic. Thus, this paper also attempts to highlight generic issues that must be solved before simulation will become a more widely used design and optimization tool. Requirements for the application of simulation for CIP/CIL plant design and optimization are highlighted. Similar problems and issues can be identified for most mineral processing plants.

Jan 1, 1994

By Mario Morin

The application of underground pre-concentration technology to narrow vein mining has the potential to change the entire economics of bulk mining methods when used in narrow vein situations. The rejection of waste at or near the face means that a higher-grade ore can be sent to surface. The waste rock can be reused directly as backfill. Swelling of the muck through blasting means that only 60 to 65% can be used as fill. Planning and scheduling of the fill usage is key to the success of this method. Through the use of simulation and system analysis, this paper examines the planning and scheduling implications of underground pre-concentration when applied to traditional narrow vein mining methods (cut-and-fill /drift-and-fill, longhole, AVOCA). It considers the logistical factors that represent potential system bottlenecks that are key to understanding the correct implementation and control strategies.

Oct 1, 2004

By Jian Wu

In this paper, the surrounding rocks and the supports in a longwall are taken as an integral, i.e. a system. The structural characteristics and behavior of the system are discussed based on in-situ observations. A set of equations, which describe the interaction among the support, immediate roof and main roof, are developed. These equations can be used to design the longwall powered supports more reasonably and economically.

Jan 1, 1989

By Gregory E. Smith

"Tensionable headed roof bolt systems are common in the U.S. mining industry. In the last 15 years or so, they have made a comeback as a hybrid system where a mechanical anchor is used in conjunction with resin. When such a system is used, it is common to use a spherical washer to comply with the requirements of 30 CFR Part 75.204(f)(8). This standard requires an angle-compensating device be used in installations where the bearing plate is offset from the roof bolt axis by an angle greater than five degrees. This paper evaluates system performance of four different traditional angle-compensating device/plate combinations including a new patented extruded plate/extruded washer system that improves overall load capacity and stretch.INTRODUCTIONA large western U.S. underground coal mine was using a fully grouted headed rebar system as their primary support. They had developed their component specifications over many years of working with suppliers to improve and optimize these components to integrate well as a system. As shown in Figure 1, the components included a patented 7 /8"" -diameter Grade 60 headed rebar bolt with a flange capable of full bar load (Walker, 2009) and a patented 8 in x 8 in Grade 3 extruded hole bearing plate manufactured by DieMatic Corporation.The mine decided to pursue a fully grouted tensionable system using a mechanical anchor as the tensioning device. Their primary goal was to eliminate the need for the roof bolt operator to secure (hold) the bolt during resin set time. An additional benefit was the increased initial tension on the bolt. To comply with the requirements of 30 CFR Part 75.204(f)(8), regarding tensioned roof bolts, they were required to include an angle-compensating device because a share of the bolt population would be installed at angles greater than five degrees from the perpendicular to the bearing plate. Also, to improve cycle time and torque/tension consistency, the mine desired to have the washers and anchors assembled at the factory. This required the use of a bearing plate with a center hole large enough to accommodate the 1-3/8-in-diameter mechanical anchor to pass though it during assembly by the roof bolt operator. The mine wanted to continue to use an extruded hole bearing plate in the tensionable system, and EMS was asked to propose a plate and angle-compensating device."

Jan 1, 2016

By I. R. Muirhead, S. Frimpong

"The mechanization of mining operations in underground coal mines has led to faster cutting rates of coalfaces with increased levels of emission of gaseous and particulate contaminants in the workings. Consequently, the fresh air streams from the main ventilation systems reaching distant workings are often insufficient, ineffective or inadequate and have to be supplemented by auxiliary ventilation systems to create and maintain the required working environments underground. The efficiencies of auxiliary ventilation systems are largely affected by drivers of the system such as the type and capacity of the fan; the type, length, diameter and condition of the ventilation ducting and the distance from the discharge end of the intake ducting to the face. Traditionally, single point measurements of methane gas concentrations using either flame safety lamps or hand-held measuring instruments have been used to assess how safe underground coal workings were. Unfortunately, such occasional measurements of methane gas concentrations do not give an accurate picture of the real gas concentration in the working as they are often taken from the easily accessible locations in working. Continuous monitoring of the methane gas concentration in development headings enables a better assessment of the environmental conditions prevailing there. All variations in the methane concentrations are more easily captured on a continuous monitoring basis than by instantaneous single point measurements. The approach adopted in this work was to continuously monitor the concentration of methane very close to the face and about 60 m outbye in development headings, observe the types of auxiliary ventilation equipment and their sizes being used in the working as well as noting the lengths from the discharge ends of the forcing and exhaust ductings to the face.In this paper, empirical methods are used to calculate the mean efficiencies of the auxiliary ventilation systems in selected development headings in coal mines in North America. This enables the assessment of the effectiveness of the auxiliary ventilation systems and the identification of the system drivers in them. The results show that the efficiencies of the forcing systems ranged from 17.02% to 96.81% while the efficiencies of the overall systems varied from 6.04% to 54.16%. The distance from the discharge end of the intake ducting to the face appeared to be the strongest driver in the performance of the auxiliary ventilation systems studied. It was also noted that when the discharge end of the intake ducting to the face does not exceed 7 m, there were faster purging rates of methane at the face and the efficiencies of the overall auxiliary ventilation system were greater than 50%. These findings are very important in underground coal mining in North America as they will assist to avert calamities, such as the Westray coal mine disaster in 1992 which resulted from the explosion of methane gas, by identifying which components of the ventilation system need special attention to create safe working conditions underground."

Jan 1, 2003

By H. A. D. Kirsten

Shotcrete has become a strategic component of support in underground mines. The ductility of reinforced shotcrete makes it a safe and economic means of surface support under adverse static and dynamic loads. The ability of ductile shotcrete to sustain load at large deflections enables excavations in squeezing conditions to be stabilized and the safety in excavations subject to rock bursting, to be assured. A Shotcrete Working Group was formed to find the configurations of fibre reinforcement that would give shotcrete the same ductility as when reinforced with mesh. Beams and panels reinforced with various types and lengths of fibre were accordingly tested. A single mix design consisting of river sand, ordinary Portland cement, fly ash, condensed silica fume and gunite dust and segregation suppressant was used. Steel and polypropylene fibre varying in length from 25 to 50 mm were used in nominal contents of 5 % and 0.5% by mass respectively. Beams, panels and control specimens were shot into specially made formers. Suitable mixing procedures were developed for the different types of fibre. The test specimens were shot in a semi-dry mix process. The shotcrete was cured until tested 28 days after shooting. The fibre contents and uniaxial compressive and Brazilian tensile strengths of the shotcrete were determined from the control specimens. The beams and panels were tested in bending in specially manufactured test rigs. The beams were examined for simple supports and fixed ends. The panels were fixed in a manner that simulated underground conditions and were loaded statically under uniform pressure. The beams were loaded and the corresponding deflections measured up to failure. The panels were loaded up to mid-span deflections of 150 mm. The results are presented in the form of load-deflection graphs. The peak loads and ultimate deflections for the fixed end beams were considerably larger than for the simply supported beams for the various types of fibre considered. None of the beams tested, however, were able to sustain load at relatively constant value beyond the peak load. The panel tests showed that 40 mm and 50 mm long steel fibre and 30 mm, 40 mm and 50 mm long monofilament polypropylene fibre reinforcement gave shotcrete the same ductility as mesh.

Jan 1, 1998

By A. Navarra, F. Mucciardi, H. Marambio, R. Parra, F. Oyarzún

"Discrete event simulation (DES) is an appropriate framework for the plant-wide analysis of copper smelters. These smelters apply a common set of chemical reactions: copper-iron sulfides are blasted with oxygen-enriched air, sending the iron into a slag phase and the sulfur into the offgas. Moreover, conventional copper smelters exhibit similar operational dynamics: a smelting furnace operates continually, feeding into an alternating set of converters that produce batches of blister copper. The thermochemical and operational commonalities of copper smelters are integrated within the DES framework. This serves as a common basis to begin evaluating the system dynamics of individual smelters. For complex problems, the simulation framework should be developed in phases, incorporating feedback from different personnel who have complementary perspectives. Sample computations are provided in this paper based on the Hernán Videla Lira smelter, whose production is constrained by meteorological conditions. IntroductionWorld copper production is approximately 18.5 million t/y (Brininstool, 2015), worth $80 billion a year. Out of this total, 75 percent comes from the pyrometallurgical processing of sulfide minerals (Fig. 1), which occurs in copper smelters. The remaining 25 percent is from the hydrometallurgical treatment of oxides and complex ores (Rotuska and Chmielewski, 2008), which uses solvent extraction and electrowinning.The current paper describes the pyrometallurgical processing, recognizing that the underlying thermodynamics and kinetics are well known (Degterov and Pelton, 1999), with the notable exception of minor element transport, such as arsenic (As), antimony (Sb), bismuth (Bi), silver (Ag), gold (Au). The latter is an ongoing area of research, as smelters are faced with increasingly complex ores (Devia, Wilkomirsky and Parra, 2012; Swinbourne and Kho, 2012). This paper focuses on the system dynamics of copper smelter operations, which has received considerably less attention than the chemical thermodynamics and kinetics.Smelter engineers and managers may contribute to the sustainability of their plant by improving their understanding of operational system dynamics. Indeed, we have prompted smelter improvement projects (Navarra, 2016; Navarra et al., 2016; Navarra and Mendoza, 2013) simply by adapting methodologies that are commonly used in other sectors. These previous works incorporate principles from computer-integrated manufacturing (Groover, 2000) and theory of constraints (Dettmer, 2007), featuring the use of discrete event simulation (DES)."

Jan 1, 2017

By E. Mataradze

Statistics shows that the majority of accidents with fatal outcome are caused by methane and/or coal dust explosion. This leads to assume that contemporary counter-explosion systems of various designs cannot be considered effective. Considering the growing threat of methane explosion in the coming years along with the development of deeper levels, the improvement of a system for protecting people in underground opening appears urgent. This paper presents the results of the testing of the Automatic System from Methane Explosion in Coal Mines. The protective system consists of: i) a wireless device for the detection of explosions and activation of a protective system, and ii) an absorber with a pyrotechnic device ensuring the discharge of dispersed water. The protective system, at the command of the initiation signal, produces tailored dispersing water mist with droplet sizes in the range of 25?400 ?m along selected tunnel sections.

Aug 1, 2013