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By R. Jerez

This paper describes practical applications of lineal" programming techniques to help in the planning of production, transportation and shipments at different coal mines. The models are being used by Cyprus Coal Company in eastern and western operations to plan coal production, economic dispatching and blending over variable time horizons. In addition, where a preparation plant exists, the models establish the amount of washing required to meet specific coal sales qualities. The emphasis on this paper is on model development and implementation together with a system to track coal flow and qualities, either raw from the mines to the loading facilities 01" processed through a preparation plant.

Jan 1, 1991

By Harry H. Peek

Artesian pressures of unusual magnitude occur in the deeper aquifer units beneath a considerable part of southeastern North Carolina and extend into South Carolina. The high pressures were first observed in 1968 in wells near Wilmington that were drilled to "basement" rock and which were screened between depths of about 260 to 300 m (meters). The pressure was recognized by Peek and Heath1 as an anomalous geo-pressure and unrelated to recharge conditions in the region. Since 1973, much new information has been obtained on hydro-geologic conditions in the area and a preliminary report on the deep artesian pressures was published in 1975.2 Most of the basic information has been obtained from groundwater research stations constructed by the Groundwater Section of the North Carolina Department of Natural and Economic Resources as a part of Ground-water studies in the Coastal Plain Region. These stations consist of an exploratory well drilled to basement rock with wells completed in each principal aquifer unit to provide data on aquifer characterestics, water levels and water quality.

Jan 1, 1977

By Wen L. Chen

The steam coal quality is less stringent than metallurgical coal quality. The steam coal is prepared either by cleaning full size range of raw coal or cleaning coarse coal only, leaving the fine coal raw. The latter scheme is more cost competitive. It is particularly applicable to U.S. eastern soft coal where low ash coal is concentrated in fine sizes. For raw coal size separation, a recently developed Rotating Probability Screen, developed by the British Coal Board, may be advantageously used for easy change of raw coal separating size and to avoid screen deck plugging when handling wet and clayey raw coals.

Jan 1, 1983

By B. R. Pothini, H. von Schonfeldt

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

Jan 1, 1983

By L. F. Moran

Rod Mill Grinding is an important and fundamental step of the concentrating process in Marcona Mining Company's plants at San Nicolas Bay, Peru. This Paper summarizes experience in regard to consumption and specifications of grinding rods based on twelve years operation of the grinding circuits. Marcona operates a Plant complex producing 10 million tons per year of beneficiated iron ore products including pellets, sinter feed concentrates, high grade concentrates as slurry and filter cake. Processing capacity is 15 million tons per crude ore per year of which 13 million are around in rod mills. A continuous testing program was carried out over the years. Initial studies of daily production operations gave indications of poor grinding rates in relation to mill size and power consumption, with a high rate of broken liners and rods. The broken nieces of rod were not automatically expelled and further interfered with grinding efficiency, while replacement of liners caused unwarranted do n tire. Objectives were to improve all phases of the Process by studying the effects of changes in rod diameter, length, alloy constituents, and volume and weight of rod charge.

Jan 1, 1975

By Robert Moore Lewis

Extensive exploration is being undertaken throughout the world in search for heavy minerals, particularly rutile and other titanium minerals. The federal government is sponsoring research involving rutile ores and recovery of stockpile-grade concentrates from domestic sources. Producers are being forced to turn to deposits with a heavy mineral content as low as 0.50% (essentially rutile and zircon). The North Carolina State University Minerals Research Laboratory investigated the possibilities of recovering heavy minerals from the amine tailings of the Texasgulf Inc.'s phosphate plant at Aurora, North Carolina. One laboratory beneficiation procedure using gravity, electrostatic and magnetic processes, resulted in the recovery of 78.7% of the heavy minerals in the amine tailings. Based on this percentage recovery and the present rate of phosphate mining, approximately 13,000 tons per year of heavy minerals (principally ilmenite and zircon) with a potential value of approximately $1,045,000 (1977) could be recovered. The economic potential for recovery of these heavy minerals appears to be favorable. A flotation procedure for up-grading the heavy minerals content in the amine tailings has been developed at the Laboratory, which could allow for concentration of heavy minerals and storing them in tailings area other than main tailings for future processing.

Jan 1, 1978

By L. Alagha, L. Sanchez-Calderon, M. Silwamba, W. Kirk

Selenium-rich metallurgical waste, also known commercially as “crude selenium,” is a byproduct of the copper (Cu) refining process. This by-product, contains ~ 90% selenium (Se), precious metals, platinum group metals (PGMs), and other critical elements. This study investigated the leaching efficiency of Se from the sludge under alkaline conditions using different oxidizing agents to enrich PGMs and precious metals in the leach solid residue. The effectiveness of each oxidizing agent during leaching was assessed and compared. Additionally, Eh-pH diagram for Se was established under specific experimental conditions and utilized to inform process optimization. Key variables, including leaching time, temperature, and oxidant concentration, were evaluated for their impact on the efficiency and the selectivity of the oxidative alkaline leaching process.

Feb 1, 2025

By George M. Hamilton

The gas producer actually dates back far beyond the period from which we first find recorded data. A partial production of producer gas can take place in any type of solid fuel grate equipment, such as a boiler, or even a fireplace if a sufficiently deep fuel bed is provided. Those of us who have watched a coal fire burning in the hearth, have no doubt noticed at times, the gases liberated by the heat burning on or near the surface of the fuel bed. So far as we know, the first gas producer was built by Bischof in Germany in 1839, followed by Ebelman in France in 1840, and Ekman of Sweden in 1845. The first large industrial development in the use of gas producers was When the two Siemens brothers of Germany patented their first combined gas producer and regenerative furnace in 1861, thus opening up the field for the use of raw, crude producer gas in heavy furnace work. In the years 1879-1881 J, E, Dowson, of England developed a producer gas cooling and cleaning plant, which extended the scope of application of producer gas to make possible its use in small furnaces and gas engines.

Jan 1, 1961

By James Paone

Subsidence movements have damaged houses, schools, streets, and public utility lines in some undermined sections of Belleville and Maryville, Ill. In cooperation with local officials and the State of Illinois, the Interior Department's Bureau of Mines is sharing experience in backfilling abandoned coal mines to demonstrate that bituminous coal mine workings in south-western Illinois can be successfully backfilled and subsidence-prone areas stabilized. Subsurface investigations revealed that mine workings are dry and underlain by underclay deposits susceptible to instability upon wetting. Backfilling will therefore be accomplished by pneumatic injection instead of the hydraulic methods used in previous subsidence-control projects.

Jan 1, 1977

By Sheldon P. Wimpfen

Forecasting, an ancient art, is con-ducted by everyone in varying degrees. It is a vital aspect of mineral production and conditions must be predicted over a long time frame in all aspects of the industry from exploration to plant construction. Although many government agencies as well as private industry make forecasts, there are insufficent "make good" analyses performed. The performance of more such studies could sharpen forecasting ability.

Jan 1, 1983

By C. J. Pritchard

Controlled recirculation of ventilation air in underground metal and nonmetal mines has the potential to improve airflow and the health and safety of miners when implemented properly. Previous research by Robinson, Marks, Cecala and others concluded that the success of a district recirculation system is predicated upon an adequate supply of fresh air and the use of a reliable monitoring system for safe operation. This recent research also showed that contaminant levels will not exceed pre-recirculation levels, and that district recirculation can improve the dilution of face contaminants, especially methane gas. To illustrate the process of implementing controlled recirculation and also to promote and give guidance to mine operators in consideration of this tool to improve mine airflow, Office of Mine Safety and Health Research (OMSHR) researchers acquired baseline airflow and contaminant data from a multi-level room-and-pillar nonmetal mine and used commercial ventilation network software to simulate base case conditions and recirculation of mine air. Mine return air baseline contaminants of dust and diesel particulate matter were at lower levels than intake air, providing the potential for improved face air quality. A ventilation model implementing controlled recirculation was developed and analyzed, showing an increase in air quantity at the face, improved intake air quality, and contaminant exposure levels below those set by statutory requirements. These results, along with conclusions reached by previous researchers, provide the basis for examining the safe and effective implementation of controlled recirculation in metal and nonmetal underground mines using this mine as an example.

By S. Pastor, S. Hahn

"As the concept of autonomous haulage systems (AHS) moves from proto-types to production-ready applications, the operating performance of the haul road will become ‘mission critical’ to the overall success of autonomy in mining. Deterioration in road performance will require remediation, human intervention and significant, albeit temporary, changes to operating procedures, to accommodate road maintenance. With autonomous trucks comes the opportunity to reduce road formation and operating width, and therefore generating potentially significantly reductions in stripping ratios and improvements to mine economics, but only if the design of the road, and it’s associated deterioration rate, is predictable and manageable, based both on the materials used to construct the road and the maintenance interventions to be carried out on the road. This paper presents the assessment of a digital photogrammetric approach to the characterization of a mine haul road surfacing, or wearing course material. Design and maintenance parameters for these roads are currently determined from physical particle size distribution (PSD) assessments of ‘in-road’ material. However, this approach does not accommodate the need, nor leverage the benefits from, AHS. The digital imaging approach is assessed in this paper, using two standard digital analysis software tools, together with in-service mine haul road wearing course samples and images which are assessed to determine the applicability and reliability of the approach to deliver a real-time assessment of haul road surfacing conditions and thus to identify the road maintenance interventions required to address deterioration. INTRODUCTION Enhancements in mine road design, construction and management for the past 20 or more years has largely been focused on short-term tactical needs. These improvements have not been matched by advances in the fundamental technologies that underpin mine road design and management, and although the quality of mine roads have probably increased, many of fundamental and longer-term issues have yet to be addressed. With AHS’s evolving from prototype to production applications, any decision to implement these systems in a mine requires a thorough evaluation of impacts, not only operational improvements, but the inter-connectivity of this autonomy technology to other organizational processes. In developing an understanding, the full interactions that may affect autonomous truck behaviour due to changes in various sub-systems or external environments, haul road conditions and operating performance is a key consideration. This is as true in autonomous as well as in conventional mine truck-based hauling systems where the mine haul road network is a critical and vital component of the production process."

Jan 1, 2015

By Ashraf A. M. A. Wali

Many of the economic resources of Egypt have been recognized and exploited for thousands of years (e.g. gold and copper). Most of these minerals, particularly those from hard-rock sited deposits, are found in complex form along with other components while those present in sedimentary sequences are largely in simple compounds or as native elements. Recognition of their characteristic settings (structure, basin development, environment of formation etc.) is the main clue in predicting and locating their presence. The main economic minerals exploited in Egypt today come from sedimentary sequences and include sodium and potassium chlorides, gypsum, sulfur, and sedimentary iron ores. Large amounts of low grade sedimentary phosphates are known but are not of economic value at today's prices. Recent intensive investigation in the north-eastern Sinai (EI Arish) and along the southern coasts of the Gulf of Suez has revealed new and extensive sulfur and chloride deposits, and considerable oil and gas are now being exploited from closely related sediments. Tin is the only mineral that is produced from hard-rock sources, and gold and copper deposits are present but not of high enough grade to be economically viable. However, a significant part of Egypt has not yet been studied in enough detail to close the door on future discoveries. Another point of considerable geological interest is the presence of diverse, modern evaporitic settings, from which we may draw the analogs for many of the older gypsum, anhydrite, chloride and sulfur de-posits. In fact these analogs are so well displayed that both the Sinai and Gulf of Suez-Red Sea evaporites (Middle and Upper Miocene) can be readily compared with these modern deposits.

Jan 1, 1990

By Jiang Su, Alan Bloodworth

"Composite sprayed concrete lining (SCL), consisting of two layers of permanent sprayed concrete separated by a layer of spray-applied waterproofing membrane, represents the latest development in SCL tunneling, but presents several challenges to designers. This paper aims to address the following issues: (1) how to simulate composite action, (2) behavior of a composite SCL tunnel, and (3) how to utilize composite action to achieve lining thickness efficiency. It firstly sets out the background to the composite SCL concept, and then presents a strategy for numerical investigation. The main part of the paper is the presentation and discussion of the simulation results, focusing on the lining deformation, load sharing and the safety margin of both linings. Interface stresses are also examined. It is found that significant secondary lining thickness reduction may be achieved by utilizing composite action. Challenges for the design of composite SCL tunnels are briefly discussed at the end. INTRODUCTION Sprayed concrete lined (SCL) tunnelling has seen rapid development over the last twenty years in the UK (Su 2013). One of these developments has been the replacement of traditional sheet membrane and cast in situ secondary lining with innovative spray applied waterproofing membrane and sprayed secondary lining system, which has been adopted in recent major projects, such as Crossrail (Pickett 2013), and brings many benefits to the construction (Dimmock et al. 2013). The combination of sprayed primary lining, spray applied waterproofing membrane and sprayed secondary lining is perceived to provide a structurally efficient lining system that outperforms the traditional lining system, which consists of sacrificial primary lining, sheet waterproofing membrane and cast in situ secondary lining. The claimed benefits in structural performance arises from the composite action between the sprayed primary and secondary linings via the spray applied waterproofing membrane, which produces a much stiffer cross-section and therefore a more efficient use of materials. Early investigations on the design of composite SCL tunnels were carried out without (1) definite and reliable long-term interface parameters, (2) a verified numerical modelling technique, or (3) consideration of different stress histories between primary and secondary linings (Thomas and Pickett 2011, Marcher et al. 2011). This paper reports the findings from a numerical parametric study on a typical composite SCL tunnel with varied secondary lining thickness. The results show that the true benefit of composite lining arises from the optimisation of the lining thickness (stiffness) ratio between the primary and secondary linings to achieve secondary lining safety and thickness efficiency at the same time."

Jan 1, 2016

By J. O. Marsden

The Candelaria copper-gold mine is located approximately 25 km south and east of Copiapo in Region III, Chile. The original concentrator was designed to treat 28,000 t/d (30,800 stpd) of chalcopyrite-bearing ore through a circuit consisting of a single 11.0 m (36 ft) diameter SAG mill, two ball mills, conventional rougher and scavenger flotation, column cell cleaner flotation, and ceramic disc filtration. The plant was commissioned in August 1994 and quickly reached capacity and expected levels of metallurgical performance. In May 1996, a decision was made to double the capacity of the concentrator by the addition of a second line of equipment. The expanded facilities were commissioned in October 1997, less than 18 months after the decision to proceed, and well within the budget. The original concentrator facilities were replicated or duplicated as much as possible, however, a number of important equipment changes were made to take advantage of industry developments since the original concentrator was designed. These included the use of Eimco 120 m3 (4,200 ft3) cells for rougher and scavenger flotation and the installation of a Svedala VTM -800 Vertimill for regrinding. This paper describes the rationale behind these changes and explores the reasons for the success of the project.

Jan 1, 1999

By W. R. Bull

This paper examines water-only cyclone performance for the cleaning of fine coal, and the effects of changes in feed flow rate, feed pulp density, and vortex finder diameter. A model is presented for performance simulation which can be used to predict products obtained based on feed washability data.

Jan 1, 1987

By J. W. Scott

The problems involved in installing, maintaining, and operating large vibrating screens have been summarized and discussed, based on a survey of current use of such screens in selected North American mineral processing applications. Practical, effective solutions for the more serious common problems are described, along with some recommendations on design practice for specifying, selecting, and installing large screens.

Jan 1, 1983

By S. H. Brown

In our work as health physicists*, we do a lot of public speaking and interaction with the public on issues related to development of uranium mining and milling (?uranium recovery?) in the US. Understandingly, the public has important concerns about this. Accordingly, this paper is presented in a ?question and answer? format in which we have tried to capture what are some of the most common concerns we hear from citizens and address them. We have attempted to do so based on the best scientific information we have, representing information well documented in peer-reviewed scientific literature and consensus positions from both national and international scientific standard setting bodies and related committees. We have included some of the more important of these scientifically-based references to support the information provided. Practical space limitations prevent completeness in this regard in some cases. Visit the Health Physics Society?s web site or feel free to contact me directly for additional references, information or detail ? Steve Brown. The health physicist?s primary objective is to manage the beneficial uses of ionizing radiation while protecting workers and the public from potential hazards. For more information on what a health physicist is and on the Health Physics Society, visit the Society?s web site at www.hps.org.

Feb 23, 2014

By James D. Cooper

Technologic advances in materials utilization during the past two decades have brought is a long way toward the point where we can make the products we need from the materials we have readily available. Notable examples are the synthesis of diamond, zeolites, quartz crystal, mullite, and mica, and the development of phosphate bonded tale. Two of these--zeolites and mullite--involve the use of clays. There is little reason to doubt that equally important advances will be realized in the next decade, and that clays will play an important role in the developing materials technology. Indeed, the stage is already set for many of them. This discussion is concerned primarily with the high quality, relatively high priced clays, kaolin, bentonite, fuller's earth and ball clay. The first three have enjoyed demand growth rates over the past two decades which on the average exceeded the growth rate for the economy as a whole. There are indications that demand for ball clay will be growing at a faster rate in the future.

Jan 1, 1970

By CAIJUN CHEN, MING ZHANG, ZHENWEI WU, FENG ZHOU, BOQUAN LI, XILIANG ZHANG, ZHOU PU

Traveling grate is a widely used process for iron ore pellet production; however, the thermal state of pellets in drying section is still unclear. In this study, the temperature distribution of drying section was investigated using computational fluid dynamics (CFD). Based on the calculated results of airflow velocity, space temperature distribution, and the temperature change of pellets, it concluded that there is a coupling effect in drying section in traveling grate. The gas with higher temperature in DDD transfers heat to UDD through the gap of the insulation board, and the temperature gradient of the pellet bed changed before reaching the insulation board. The characteristics of pellet bed expected to appear in DDD was displayed in UDD in advance. Moreover, a contrast experiment was conducted to verify the model.

Feb 1, 2021