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By J. Herbst, J. Groppo, A. Noble, R. Q. Honaker

"Coal and coal byproducts produced annually contain a sufficient amount of rare earth elements (REEs) to meet current U.S. demand. The REEs exist in the form of minerals, ion-adsorbed elements associated with clays, and chemically bonded elements within the organic coal matrix or host mineral. Researchers at three universities collaborated to evaluate the effectiveness of existing physical and chemical concentration processes for the recovery of the REEs. The efforts found that physical separation processes can increase the total REE content in the thickener underflow material collected from a Central Appalachian coal cleaning facility from around 300 ppm to values greater than 17,500 ppm on an ash basis. Leaching followed by solvent extraction was found to be the most effective to recover the REEs from coarse middlings materials collected from multiple coal basins, as indicated by recovery values exceeding 80 percent. Based on material characterization data and process evaluations conducted for several potential feed coal sources, economic recovery of the REEs will require byproduct production of both clean coal and REE concentrate using a process flowsheet that is unique for each source. IntroductionRecent studies initiated by the National Energy Technology Laboratory showed that U.S. coals contain significant amounts of rare earth elements (REEs), suggesting that rare earth minerals (REMs) and/or REEs can be produced as byproducts (Ekmann, 2012). According to the report, the richest source of REEs is the Central Appalachian coal. At present, there are 208 coal preparation plants located in the region consisting of areas within the states of West Virginia, Kentucky, Pennsylvania, Virginia, Alabama and Tennessee, with a total capacity of 166,495 t/h, or more than 1 Gt/y (Fiscor, 2014). If only a portion of these plants are retrofitted with advanced separation processes, the U.S. coal industry would become a significant producer of REE concentrates as byproducts. An inherent advantage of becoming a byproduct producer of REEs is that no mining cost needs to be part of the production cost."

Jan 1, 2017

By Howard N. Egan

EASTERN COAL CORPORATION is located in the heart of the Appalachian Mountain area of extreme Eastern Kentucky, The mountains are of sedimentary origin, and have been deeply eroded by streams as the area has been thrust up during geologic time. There are many seams of coal interspersed between beds of shale and sandstone. While some of the seams are thin, there are a number that can be economically mined. We are mining the Pond Creek, or No. 2 Gas Seam, at a rate in excess of 6,000 tons per day. Our central preparation plant utilizes tromp baths for the plus 3/8" size and Rheolaveur for the minus 3/8" portion. No provision was made to recover the fine coal, which was included with the plant effluent pumped to a 12 acre refuse pond. The pond is impounded behind the coarse refuse dump. This pond rose 15 feet last year. Obviously, no pond could stand many years at this rate. Limited pond space in this rugged area of steep hills and narrow valleys dictated a revised disposal method. Our first thought was that it would be necessary to dry the fine refuse sufficiently to permit inclusion with the coarse refuse, which is hauled uphill by monitor and then trucked to final disposal.

Jan 1, 1967

By Zhiyuan Ma, ZUI WANG, Xincheng Hu, Jianwei Cheng, Junhong Si, Yi Qin, Gao Ke

The harmfulness and destructiveness of mine gas explosion is quite serious, which is the first of all kinds of coal mine disasters. Once the gas explosion occurs, it could instantly generate explosion shock waves, high temperature airflows, and disaster gases, which cause the destruction of underground ventilation structures, disruption of airflow direction in a mine ventilation network, and miners’ deaths by asphyxiation. As an important barrier to prevent the spread of accidents caused by the gas explosion, the safety and reliability of the mine seal affects the mine’s production and the health of workers. Due to the demands of coal mine production and transportation, a large number of longitudinal and horizontal roadway networks have been developed underground. There are not only many flat and straight roadways in the complex roadway network structure, but also a large number of different types of bifurcations and bends. Once a gas explosion occurs, the impact of the blast waves on the mine seal after passing through the complex path is difficult to determine. Therefore, this paper establishes a numerical model of bifurcated and cornered roadways and studies how the impact of gas explosion shock waves on the structure of sandwich mine seal after passing through different types of bifurcated and cornered roadways. The damage state of sandwich mine seal is analyzed. The researching finding could prevent and manage the spread of gas explosion disaster, and improve the disaster mitigation of mine explosion accident.

Jul 11, 2023

By Wang Ding-heng, Wang Zhi-yuan, Nolan B. Aughenbaugh

The People's Republic of China has abundant coal resources with proven reserves amounting to 582 Gt (641 billion st). Recognizing coal as a major energy source on which to build the country's industrial and economic base, there has been a rapid increase in production since the founding of the People's Republic. In 1949, only 29.4 Mt (32.4 million st) of coal was mined. Production has increased to 576.5 Mt (635.5 million st), exclusive of Taiwan, at present, making China the third largest coal producing country in the world. Plans call for a 4-5% increase in annual production for the next 20 years. Coal constitutes 70% of the primary energy consumption in China. The remaining 30% is divided between petroleum and natural gas with 26% and hydropower with 4%. Coal use and consumption is divided as follows. General industrial use comprised 48.9%, power generation uses 20.1%, and coking accounts for 10.5% (6.3% for metallurgy and 4.2% for chemical industry). Domestic use such as home heating and cooking makes up 17.8% and coal-fired steam engines for railways uses 4.7%. Coal Districts Coal underlies about 1/18 of China's land area. It occurs in 30 provinces, autonomous regions, and municipalities. In addition, the western interior region, which has not been explored, may contain sizable reserves. Based on geology, geography, and administration, the coal fields can be grouped into five districts as shown in Fig. 1. The north China district, the heart of the industrial base for the country, has the most extensive and largest deposits of the five districts. This amounts to almost 40% of the country's total reserves. The largest coal basin with proven reserves of 181.4 Gt (200 billion st) and the most exploitable seams is located some 300 km (186 miles) southwest of Beijing (Peking) in Shanxi Province. Centered around Taiyuan, the compound field extends from Datong in the north to Xian in the south. Its western extension is not known fully. The Northwest and Northeast districts contain the second and third largest deposits. The biggest coal field in South China is located in the Sichuan and Guizhou Provinces near Chongqing. At present, it is not known if sizable coal measures exist in the Tibetan district. Coal Types China's coal varies widely both in age and rank. Geologically, coal measures were deposited from the lower Carboniferous (Pennsylvanian of the US) and Permian of late Paleozoic, mainly during the Jurassic of the Mesozoic and peri¬odically throughout the Cenozoic. Collectively, coal from the lower Carboniferous, Permian, and Ju-

Jan 3, 1983

By James E. Jones

The coal mining industry is being called upon to vastly increase production in the coming years. Many mining operations will have to prepare an environmental impact report of some kind and all will have to comply with various types of environ- mental regulations. Therefore there is a great need within the industry for access to environmental data, information, and literature. This paper discusses the informational resources available, the current lack of access to these resources, and the Environmental Data, Information and Literature (EDIL) Bank of the Kentucky Institute for Mining and Minerals Research. The bank's major emphasis concerns the environmental, social and economic aspects of producing clean solid, liquid, and gaseous fuels from coal. The data bank promotes information interchange between other related governmental and private projects and the energy development community.

Jan 1, 1976

By Daniel Hodouin

Artificial neural networks (ANN) are of growing interest in a wide variety of applications. Pattern recognition, speech processing, financial analysis, signal processing and process control are at present the most successful ones. This paper is an attempt to illustrate the potentiality of ANN applied to mineral processing. An introduction to the technology of ANN is first proposed to describe the various components and to explain the various phases encountered in setting up a network. Then examples are given to illustrate the use of ANN dynamic modelling of mineral processing units or plants and in process control.

Jan 1, 1991

By D. W. Park

Longwall mining is considered the most efficient underground coal mining technique in terms of coal extraction ratio, production rate, and safety standards. Due to the increasing demand for higher coal production, wider panel and faster face movement have become the recent trends. Thus, longwall mining can create unexpected threats such as roof falls, excessive face convergence, shield damage and numerous maintenance problems causing sudden interruption of coal production and serious safety hazards. A recent study at the University of Alabama is dedicated to develop LoSCoMS (Longwall Strata Control and Maintenance System) which integrates real-time shield monitoring, data presentation, analysis, forecasting, and warning modules. The main objectives of this system is to provide the stability and maintenance information, at every minute, such as high load, low setting pressure, leg leakage, etc., analysis of various mining and geological parameters to determine past and present roof characteristics and forecasting of loading patterns for the following mining cycles, next periodic weighting, etc. Using this unique system, mine operating personnel are well aware of past, present and future roof loading patterns at the longwall face, and thus, proper safety measures can be taken ahead of time.

Jan 1, 1997

By David M. Abbott

This paper is a companion to, and amplification of, the ?History? section of the 2014 version of the SME Guide for Reporting Exploration Results, Mineral Resources, and Mineral Reserves (SME Guide). The need for the careful examination and evaluation of mineral deposits has long been recognized. In the book De Re Metallica, Georgius Agricola noted, ?Moreover, a prudent owner, before he buys shares, ought to go to the mine and carefully examine the nature of the vein, for it is very important that he should be on his guard lest fraudulent sellers of shares should deceive him? (1556, p.29). Agricola further stated, ?Now a miner, before he begins to mine the veins, must consider seven things, namely: the situation, the conditions, the water, the roads, the climate, the right of ownership and the neighbors? (1556, p. 30). The elements of Agricola?s seven things, much expanded, are incorporated into the 2014 SME Guide. As reflected in this quotation, veins were the primary concern of mining until 20th century technology permitted bulk mining techniques. The need for standardization of reserve descriptions arose along with the development of western mining in the United States and the concurrent development of mining engineering and mining geology as professions. By the turn of the century, debate about terminology of various classes of reserves was in full swing. Herbert Hoover noted in 1909 (p. 16-17), ?The old terms ?ore in sight? and ?profit in sight? have been of late years subject to much malediction on the part of engineers because these expressions have been so badly abused by the charlatans of mining in attempts to cover the flights of their imaginations. A large part of Volume I of the Institution of Mining and Metallurgy has been devoted to heaping infamy on these terms, yet not only have they preserved their places in professional nomenclature, but nothing has been found to supersede them. ?Some general term is required in daily practice to cover the available field of visible ore, and if the phrase ?ore in sight? be defined, it will be easier to teach the layman its proper use than to abolish it. In fact, substitutes are becoming as badly abused as the originals ever were. All convincing expressions will be misused by somebody.? Hoover (1909) noted that the common terms at the time were: ? Positive ore or ore developed: Ore exposed on four sides in blocks of a prescribed size. ? Ore blocked out: Ore exposed on three sides within a reasonable distance of each other. ? Probable ore or ore developing: Ore exposed on two sides, ? Possible ore or ore expectant: Ore in whole or in part below or beyond the range of vision. Hoover stated that these, and similar terms, overlapped and had the difficulty of failing to account properly for geologic variation in metal distribution beyond the exposed face. Certainly assuming extension of values along a vein is reasonable, but how far? Also, these definitions are for vein deposits, not all types of deposits are in veins. Hoover (1909, p. 19), therefore, defined the following terms. ? Proved ore: Ore where there is practically no risk in failure of continuity. ? Probable ore: Ore where there is some risk, yet warrantable justification for assumption of continuity. ? Prospective ore: Ore that cannot be included in the above classes, nor definitely known or stated in any terms of tonnage.

Feb 1, 2014

By Charles A. Stone, Eric C. Wang

"Top-down wall construction was selected to excavate the tunnel portal headwall areas of the ORB East End Crossing tunnel. Benefits included an expedited construction schedule realized by staging excavation and rock support with development of temporary construction access roads. Rock mass properties, proximity to right-of-way lines, and blasting impacts were considered to design suitable lift heights, intermediate bench locations, and permanent ground support systems to provide supported permanent excavations. Carbonate rock formations contained adverse subsurface geotechnical features including solution cavities, clay seams, weathered joints, pinnacled rock, and boulders, which were addressed by flexibility in design. The resulting over-break conditions and long-term water infiltration issues required economic design solutions. This paper discusses the unique considerations required during design of top-down tunnel portal headwalls excavated in carbonate rock formations including temporary excavation and permanent ground support systems which provided flexibility for unforeseen over-break, minimized construction delays, and provided long-term stability. PROJECT BACKGROUND The East End Crossing is an approximate 8-mile highway connection of the Louisville-Southern Indiana Ohio River Bridges East End Crossing (ORBEE) project. Currently under construction, this connection will link State Road 265 in Indiana with the Gene Snyder Freeway in Kentucky to form an outer loop bypassing the Louisville-Southern Indiana metropolitan area. This highway project features a 2,510-foot long, three-span cable-stayed bridge over the Ohio River, and a 1,680-foot long tunnel. The project, being managed by the Indiana Finance Authority and Indiana Department of Transportation, is scheduled to open to traffic by the end of 2016. The new twin three-lane tunnel under the historic Drumanard Estate requires steep cut excavations for approach and tunnel portal walls on the order of 60 feet deep through overburden soil and carbonate bedrock formations. This paper focuses on the design considerations for the permanent support of the top-down wall construction of the tunnel portal headwalls and approach retaining walls."

Jan 1, 2016

By Faruk Oksuz, Dave Schiemann, Matt Trotter, Mike Padilla, Carmen Scalise, Miquel Sanchez

"The McCook Main Tunnel system consists of a 10-m (33-ft) finished diameter, 490-m (1,600-ft) long, hard rock tunnel constructed from a 27.5-m (90- ft) diameter and 92-m (300-ft) deep main gate and tunnel construction access shaft. The gate shaft houses six, high-head 4.4 m by 9 m (14.5 ft by 29.5 ft) wheel gates to be installed in the bifurcated and steellined section of the tunnel. The tunnel also includes portal and energy dissipation structures as it daylights into the reservoir.The construction of the tunnel system has been divided into two contracts. The gate and construction access shaft was completed in August 2011. The tunnel excavation and concrete and steel lining was completed in September 2014. The remaining and undergoing construction include the tunnel connections to the reservoir and the Mainstream Tunnel and installation of gates and hydraulic cylinders. This article focuses on the live connection of the McCook Main Tunnel to the Mainstream Tunnel that was initiated in November 2014 and will continue through the seasonal drier weather conditions in Chicago approximately from October through April. Chicago TARP systemThe MWRD has been addressing combined sewer overflows (CSO) and flooding in Chicagoland since the late 1960s and formally adopted the tunnel and reservoir plan in 1972 to protect the region’s most precious drinking water supply, Lake Michigan. Phase I of TARP, which included construction of 175 km (109 miles) of deep storage and conveyance tunnels with diameters up to 10 m (33 ft), was completed in 2006. In addition to protection of Lake Michigan from CSO discharges, Phase I resulted in substantial improvements in surface water quality as well as the quality of life for lake and riverfront communities in Chicago. Water quality improvements and flooding mitigation will be further enhanced as Phase II reservoirs are placed in service, including the three large reservoir systems, McCook, Thornton and Majewski (Fig. 1).The McCook Reservoir is the largest reservoir in the TARP system. Once completed, this $700-million reservoir facility will receive 38 billion L (10 billion gal) of CSO and flood water via the McCook Main Tunnel, which connects the TARP Mainstream Tunnel to the McCook Reservoir, and from distribution and Des Plaines inflow tunnels which will bring flow from the Des Plaines Tunnel of TARP."

Sep 1, 2016

By Gary Brieley

Until well into the 20th century, most construction work was performed under the auspices of a master builder or in a manner that would be described today as design-build. In addition, many civil engineers served as ?interns? under the tutelage of a master builder in order to learn how to design and construct a certain type of structure. This was certainly the case for tunneling projects with various individuals having been identified as tunneling experts as a result of successfully completed projects The master builder approach began to change in the early 1900s to a model that would be referred to today as design-bid-build. A design-bid-build approach to project procurement gives the owner more control over the final product and al-lows the contractor to know exactly what is expected of them before the work is constructed. As a result of this transition in project procurement, civil engineering schools placed a greater emphasis on the training of ?design? professionals. This article will document how the training of tunnel design professionals progressed within the United States. Although it is difficult to generalize about the hundreds of tunnels that were constructed in the first four decades of the 20th century, there is one project that stands out as having resulted in a university program related directly to tunneling and that is the Chicago Subway. During a visit to the United States in 1938, Dr. Karl Terzaghi met a student named Ralph Peck who was then studying at Harvard University in a pro-gram established by Arthur Casagrande. Shortly thereafter, Terzaghi traveled to Chicago for a lecture and was asked to consult on the Chicago subway project that was then under construction. The Chicago subway was being constructed in clay, and the owners were worried about possible settlements to nearby buildings. Terzaghi asked Peck to serve as his field engineer for that project. Thus was established one of the most productive relationships in the history of civil engineering in the United States. Peck, who would become Dr. Peck, moved to Chicago in 1939 to participate in an extensive research project that con-tinued until subway construction was halted in 1941 because of World War II. During that time, the cost of subway construction in Chicago was reduced substantially as a result of Peck?s observations and Terzaghi?s recommendations. In fact, it was reported that subway construction in Chicago cost less than one-half of similar projects in London even though the clay in London is considerably stiffer compared to Chicago. Upon the completion of his work on the Chicago Subway, Peck accepted a professorship with the University of Illinois in Champaign/Urbana.

Jun 1, 2010

More than 100,000 people from 110 countries involved in the construction aggregates and ready mix concrete industries are expected to attend Conexpo-Conlagg '99 in Las Vegas, NV March 23-27. The exhibition, the largest of its kind in the Western Hemisphere, takes place every three years. It is held at the Las Vegas Convention Center, Las Vegas Hilton Center and Pavilion. The show serves as a venue for con- tractors and others involved in aggregates construction to view the latest in equipment, technology and services. More than 1,500 exhibitors will use more than 147,200 m2 (1.6 million sq ft) of indoor and outdoor exhibit space. Attendees include presidents and company owners, sales and marketing managers, general managers and project managers. An estimated 20% of the attendees will be from outside of the United States. New for the Conexpo-Conlagg '99 show is a 3,715- m2 (40,000-sq ft) Information Technology Pavilion. This event, organized by AIEIC Systems, will showcase computer technology for the architectural, engineering and construction industries. Shown in the pavilion will be the latest developments in cost management, estimating, bidding, project management and accounting. In addition, the Information Technology Pavilion will demonstrate the latest in computer-aided design software, systems and services. Conexpo-Codagg '99 will also emphasize live demonstrations of exhibitor's products. Individual exhibitors will demonstrate their machinery so attendees can see the latest technology in action. Because the Conexpo-Codagg exposition is so large, "shows within a show" have been created to help attendees locate the products and services best suited to their interests. Seven product concentration areas will be formed. Each area houses suppliers and manufacturers of similar products or services.

Jan 1, 1999

By Lauro Lacerda

Shotcrete is a highly adaptable and widely used underground construction material at infrastructure and mining projects around the world. In fact, many projects could not have been completed without its utilization. As underground projects became larger the use of mechanized wet-mix spraying gradually replaced manual dry-mix shotcrete applications. This paper details some of the reasons for that and provides information on the equipment and operational factors including safety and productivity required to successfully complete underground shotcrete projects.

Jun 13, 2021

By Phillip Crowson

The annual surveys of corporate exploration expenditures carried out by Metals Economics Group (MEG) show that estimated total spending rose to a record $13.2 billion in 2008 ($14.4 billion including expenditure on uranium exploration). This compares with the previous peak of $5.2 billion in 1997. MEG does not adjust its figures for the effects of inflation but recognizes that the substantial increase in budgets of recent years has not been reflected in a proportionate rise in actual activity on the ground (MEG, 2009). In recent years, costs were boosted by rising prices of fuel and other inputs, and acute shortages of qualified staff and drilling rigs. The inflation rate for exploration substantially exceeded increases in general price levels as measured by national indices. Just how much exploration costs in-creased, however, is probably not widely appreciated. Figure 1 compares the MEG estimates of total annual dollar spending in Australia, Canada and the United States combined with their drilling activity, measured in meters drilled, as reported by national agencies. These three countries accounted for 39 percent of MEG?s estimate of total spending on minerals exploration in 2007 and 40 percent in 2008. Expenditure is shown both in money terms, as reported by MEG, and adjusted to real terms, with the U.S. implicit gross domestic product (GDP) price deflator. The comparison is of index numbers based on 2000 as 100. Comparisons for the individual countries are shown in Fig. 2 to 4. National figures for drilling activity and expenditures cover some minerals like iron ore, coal and industrial minerals (29 percent of Australian spending in 2007 to 2008 and 10 percent of Canadian in 2008) that are not included in the MEG estimates of spending. Such exploration has risen more than the total since 1997 so that the index of drilling activity in the figure may be overstated for recent years on a like for like basis with the MEG data. MEG only includes spending on uranium exploration in recent years whereas the national agencies include it throughout. Figures 5 and 6 com-pare national and MEG estimates for Australia and Canada. No comparable figures are available for the United States. The national estimates have been converted to U.S. dollars at the appropriate annual average exchange rates, and the Australian annual totals have been summed from the published quarterly data. Not only is spending cyclical, but so are unit costs. Australian and Canadian data show that total exploration spending per meter drilled rose by 2.5 to 3 times between 2001 and 2008. These rises may partly reflect increasingly complex drilling methods, and an increased share of assaying and testing in total exploration costs. In Canada, however, diamond drilling accounted for a lower footage of the total in 2005-2007 than in the preceding few years, and spending on exploration, as opposed to deposit appraisal, made up a higher proportion of the total. Figure 7 compares index numbers of exploration spending per meter drilled in U.S. dollars for Australia and Canada. These figures raise a number of questions. First, is the relationship between total expenditure and meters drilled in the three countries for which data are available typical of the global experience? Secondly, has there been a significant change in the make-up of exploration spending in recent years? The Canadian data do not suggest that there has been, but is Canada typical? Has drilling become less important relative to other exploration techniques, or is it just as important as ever in confirming the existence of viable ore deposits?

Jan 1, 2009

By James H. Boettcher

In the second quarter of 1979, ASL Inc. inquired whether Crocker National Bank ("CNB") would provide $4 million in term loan financing to help ASL acquire the outstanding shares of the S&S Coal Company in West Virginia. ASL had, prior to approaching CNB, sought financing with the assistance of a financial advisor from a number of commercial banks without success. A summary of the initial terms requested by ASL is shown in Table I compared with the actual terms the transaction closed with. It is not difficult to note that the two sets of terms differ significantly. This is often the case when financing requests based on the expectations and vision of a mine developer are juxtaposed with more pragmatic requirements of a commercial bank. The "art" and fun of structuring financing plans for mining ventures (highly leveraged acquisitions or grass roots) comes in working with mine developers to arrive at a final financial structure that meets their objectives and constraints as well as those of the bank or other financial institution providing much of the financing. This article briefly describes the process we went through with ASL beginning with the terms they requested initially and ending with the ones on which the transaction was finally closed.

Jan 1, 1981

By William Bergeson

This paper presents the challenges of the Homestead Avenue Interceptor Extension (HAIE) project in downtown Hartford, Connecticut. The new 72-inch (1,830 mm) sewer pipeline project consists of installing approximately 3,010 linear feet (920 m) of PVC lined reinforced concrete pipe using pressurized face microtunneling. The entire alignment is located within soft to very soft, varved silt and clay. To the extent possible, the alignment was selected to avoid bedrock, glacial till, miscellaneous fill,buried steel piles, and utilities. Challenges for this project include low ground cover, crossing major transportation routes, and limiting settlement to prevent damage to historical buildings and critical utilities. The machine was selected for the ground conditions. Design calculations were performed for selecting the reinforced concrete pipe class and for evaluating settlement. The potential for settlement damage was evaluated using both conventional analysis and finite element analysis

By Stephen G. Hardcastle, Michel G. Grenier, Kevin C. Butler

Today there are numerous electronic rotating vane and thermal (hot-wire) anemometers, as well as vortex meters available to measure air velocity. Of these, a laboratory and field evaluation has found that certain instruments are better suited to routine airflow measurements in mine roadways and ventilation ducts. This paper concludes a study sponsored by the Atomic Energy Control Board of Canada, that was introduced at the 5th U.S. Symposium. The study investigated the suitability of currently available electronic anemometers as replacements for the traditional mechanical analog devices while maintaining standard methods such as the continuous traverse. Six electronic instruments were subjected to extensive tests under controlled conditions both in a wind-tunnel and in the field at an underground mine. The evaluation concluded that ergonomics and design were major considerations in unit preference as most of the instruments had very similar performance characteristics. Specific findings were: a) In the wind-tunnel the vane anemometers, especially the "micro" vanes, were more susceptible to misalignment or yaw effects but these were not noticeable in the field; b) Both the vortex and hot-wire anemometers were suitable for continuous traverses of mine roadways; c) Traversing ventilation ducts was more practical than a Pitot-tube multi-point assessments or discharge measurements; d) Yaw is a major concern in duct measurements; e) The continuous traversing method for roadways overestimates the average air velocity; f) Hot-wire anemometers can require significant air density corrections; and g) Hot-wire anemometers are better suited than rotating vanes to mine roadways of less than 1 m/s average air velocity. Based on research detailed in this paper, the ventilation engineer should be able to match the mine's requirements with the presented instrument performance characteristics, thereby optimizing the purchase of a new anemometer and the efficiency with which air velocities are measured.

Jan 1, 1993

By Kim A. Lapakko, William W. III White

The ASTM standard method D 5744-96 was developed to provide a well-defined kinetic test protocol, conducted under controlled reaction conditions, with the intent of generating reproducible results. The US Bureau of Land Management, American Assay Laboratories, and the Minnesota Department of Natural Resources cooperated in a intralaboratory and interlaboratory testing of the protocol. Intralaboratory testing was conducted on duplicate samples of gabbro (8) and siltite-argillite (5) rocks for periods of 20 to 125 weeks. The difference between replica& intralaboratory pH readings on drainage from the gabbro for the drip-trickle leach alternative typically did not exceed 0.1 units, although differences as high as 0.4 units were observed. The difference from the mean for rates of sulfate, calcium and magnesium release was typically within 10%. Intralaboratory results for the siltite-argillite samples were generally similar, although a one unit pH difference was observed for one sample. Three different laboratories tested a gabbro sample for 125 weeks, with a maximum difference from the mean pH of 0.5 units. The percent difference from the mean for sulfate and calcium release rates was typically within lo%, although values as high as 30% were observed. Data on intralaboratory and interlaboratory agreement on the flood rinse alternative of the method were limited. Replication on the sample tested was comparable to of better than that observed for the drip-trickle method testing of the same sample.

Jan 1, 2000

By John Mastoris, Shkurta Gashi, Kostis Dragasakis, Kostas Kouklidis, Halil Berisha

Water is increasingly recognized as a critical issue for sustainable development, becoming as important as carbon to corporate responsibility and reputation. Although the cement industry’s overall ‘water footprint’ is relatively small compared to other sectors, the Cement Sustainability Initiative of the World Business Council for Sustainable Development (WBCSD/CSI) has recognized the importance of water and the need to take actions towards efficient water management, with developing standardizing practices and employing a risk-based assessment approach, mostly at local level where individual facilities and activities can have implications for other water users in the area. Sharrcem, a member of the Titan Cement Group, has made significant investments to upgrade its production facilities, the technological process and apply environmentally friendly technologies. Under this frame, Sharrcem implemented a project for the construction of a Waste Water Treatment Plant (WWTP) in the Cement Plant facilities, which has been successfully operating since early 2016. This paper discusses the technology applied at the new WWTP and the results achieved already, with significant improvement in the quality of the treated water, as compared to the previous situation where untreated wastewater was directly discharged to the nearby Dimce Stream. The WWTP project is a major investment of Sharrcem that aims to improve the quality of the discharged water effluents and thus prevent potential river pollution and overall protect the environment and the health of Sharrcem employees and local community. The WWTP operates with the Sequencing Batch Reactors (SBR) technology, is fully automated and has been also connected with few households of the neighboring community to treat also their sewage water. The plant can be expanded in the future – to connect with additional households - without increasing the size of the treatment tanks. One of the benefits of this project is that by removing a variety of contaminants from water it becomes usable again, depending on the nature of the contaminants and the end use of the water treated. According to the monitoring results the treated water that comes out of the WWTP fully meets quality requirements according to the EU and local limit values standards

Jan 1, 2017

By B. E. Davis, D. A. Stanley, C. E. Jordan

A prototype expert advisor was developed by the U.S. Bureau of Mines to systematically offer advice on the control of a Florida phosphate operation. The PC based system receives input from remote sensors for circuit parameters such as feed rate, reagent addition, and pH and from operator entered information such as the quality of the concentrate and tailings in each of the coarse, fine, and amine flotation circuits. The computer evaluates the information using rules obtained from industry representatives and Bureau flotation experts. Recommended actions and questions are displayed to quickly guide the operator to a problem within the flotation circuit and suggest a solution. This process control system could provide more uniformity among the flotation operators and also serve as a trainer for new operators. In addition, it represents a step toward fully automated systems for phosphate flotation.

Jan 1, 1990