Search Documents

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 P. G. Irwin

Natural resins, those derived from coal and those mined in the Uintah basin, face challenges from synthetic resins that are derived from petroleum sources and rosin or wood sources. In the past, fossil resins from coal were produced by various companies, the last one being Hercules, Inc., which sold BLACKHAWK resin until a fire destroyed the plant in the mid 1970's. Approximately four to fjve million pounds of BLACKHAWK were produced and sold mostly to the printing ink industry. Uintaite, more commonly known as Gilsonite® resin, was widely used by various industries, notably in printing inks, coatings, stains, adhesives, foundry, asphalt paving, and oil well drilling muds. Gilsonite has lost market share over the last thirty years to various synthetic resins particularly hydrocarbon resins that are derived from petroleum sources.

Jan 1, 1990

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

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

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 John W. Conn, Harry C. Verakis

An explosion in an underground coal mine can have a devastating effect on the main fans used to provide mechanical ventilation. The Code of Federal Regulations, Title 30, Part 75.310 (CFR, 1992), specifies that each main mine fan shall be offset by at least 15 feet (4.6 m) from the nearest side of the mine opening unless an alternative method of protecting the fan is approved in the ventilation plan. Also, each main mine fan shall be protected by one or more weak walls or explosion doors. This paper presents venting and fan configuration designs which provide a comparable degree of safety for explosion protection. Design flexibility is enhanced and a means for consistency in safety judgements is afforded.

Jan 1, 1993

By Eugene Honeycutt, David Gallagher, R. E. Melley, Nick Madison

Drummond Co. Inc.'s Shoal Creek Mine slope conveyor is the highest lift, highest horsepower, highest tension conveyor system in North America. The system has a capacity of 4950 t/h (5500 tph), a vertical lift of 360 m (1180 ft) and a total connected power of 6000 kw (8000 hp). The mine will include 2 longwall machines and 5 to 7 development sections. Annual raw production will approach 9 million tly (10 million tpy). This paper describes the early investigation of system capacity, haulage system options, and the final selection of a single flight belt conveyor. It will review the basic system de- sign and equipment selected. Also included will be some highlights of the installation of the conveyor system.

Jan 1, 1996

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 Michael T. Ballard

The key to productive computer usage is system software integration with full compatibility among individual components. The majority of software developers in our industry are still in the process of perfecting individual components. As a result, exchange and validation of data between disciplines becomes an arduous process. We at Morrison Knudsen Engineers, Inc. (MKE) have integrated an entire system, allowing exploration, geology, modeling, mine planning, and operation modules to work as a single, complete system with direct exchange and validation of data. The importance of integration to both developers and users of today's mining soft- ware is becoming increasingly apparent as we, an industry, move toward growth and enhancement of the technology of ore reserve acquisition, evaluation, and management. It is also important to understand the present state of integration and where it is leading US. Not long ago, another industry passed through the same stages we are now setting up for the mining industry. The stereo industry began with a few individual components, the record player, tape recorder, and radio. People were able to play records, listen to the radio and record conversations and music only through microphones on their tape recorders. Soon, one enterprising individual discovered he could tape sound directly from the radio or record player by capturing audio output from the speaker wires. Interfaces and patch cords were developed, providing a means to transfer audio information between components with not only little loss of sound quality, but also the elimination of back- ground noise. The industry took another step forward with the introduction of "integrated" stereo, where the components were packaged in one cabinet with shared resources. This reduced overall cost which paved the way for better quality. Today's stereos are now so well integrated that many of the components share data and resources from the same manufacturer, designed to work together for almost perfect data transfer between any of the components. The result is better sound, convenience, and reduced cost. This is the ultimate goal for integration. Any system development passes through these same steps on the road to total interaction. Initially, the components are designed, tested, and marketed individually, often by separate companies. As the users become familiar with the components, the need arises for an automatic interface between the components. This is necessary to cut down on error during data transfer and to eliminate the redundant work required to enter results from one component into the next component in the system. As a result, interfaces must then be developed to aid in this data transfer. After data transfer is accomplished, the next step is resource sharing. Resource sharing is careful design and engineering by either cooperative, individual manufacturers or one firm taking on the task to produce a single package product. Design and resource sharing leads to lower overall cost, while still providing component capability with options to grow as the user grows. The mining software industry has been working to develop some very high quality component software and has indeed accomplished this task in every aspect of the mining industry. However, realizing the importance of integration, some companies with limited individual resources have started working together to interface their individual components. Other firms have undertaken the project of developing complete, integrated systems.

Jan 1, 1987

By L. M. Klimov

In recent gears in the coal industry a great deal of attention is attached to the questions of elaborating and introducing the problems of planning and management and, first of all, in the sphere of mine production. The basis for planning of mi- ne production is complexes (sets) of problems for planning the development of mining operations based on different time periods, ensuring the follow-up of changes of mine productive capacities. Complexes of problems for planning, the development of mining operations at existing underground and surface mines within the OASUugol system (Coal Industry-wide Automatic System of Management) are aimed at ma- king decisions close to optimum, i.e. general lay-out of panels, blocks and pillars; transport and ventilation networks; schedules for working out parts of mine take; coordinated mining operations with limited labour and material resources; control of mining operations and ultimately maintaining productive capacities of existing mines at the required level.

Jan 1, 1979

By w. Chruscielewski, T. Domanski

INTRODUCTION Concentration of radon 222Rn and its decay products occuring in the Polish mines of metal-ores call for the necessity of systematic radiation control /Do8la/ both of the working environment and of the miners' personal exposure. The attempts at introducing a system of radiological protection in mines, similar to the ones existing in X-ray or isotope laboratories, took several years and consisted of development of the methods for control of concentration of radon and its progeny in the air, as well as the methods for measuring individual exposure. It was accepted that the assessment of both transient concentration in the air and of personal exposure are basic elements of the control system, which should be implemented independently of each other. Concentration measurement serves to detect and to determine those areas in mines where there is intensive radon emanation, and where current control of the effectiveness of technology introduced to deacrease the concentrations is necessary; personal dosimetry results in the assessment of the actual exposure of miners to radiation. PRINCIPLES OF THE SYSTEM The assessment of working environment is based on concentration measurements of the potential radiation energy of radon alpha decay products. Decentralized assessment is carried out by the special dosimetric service operating in each mine. Dosimetrists are equipped with portable radiometers, type RGR-11, made by the institute of Nuclear Research, Warsaw. The radiometer is presented in Fig. 1. Measurement of filter activity is performed automatically according to Markov's method /Ma62/ or any other method. Simultaneously to potential energy measurement the dosimetrists are measuring the dust concentration in the air and ventilation rate. Ventilation service looks for correlation between those indices and the concentration of radon daughters in the air. Derived Air Concentration /DAC/ for concentration assessment was accepted to be 6.25 10-6 Jm-3 /0.3 WL/ according to ICRP recommendation /Publication No. 24/ /ICRP77/. If environmental measurements reveal potential energy concentration exceeding the value of 0.3 DAC at working places, the miners employed there are subject to individual control of personal exposure. Individual exposure measurement is carried out centrally by the Institute of Occupational Medicine in [Lodz] for all metal-ore mines. Miners who are to be included in the control scheme are referred by a mine management to the Institute where they are registered and assigned a dosimeter. A passive dosimeter with

Jan 1, 1981

By M. A. Qianjie

The problems of coalmine safety in china remain unsolved for decades. Starting with the description on safety status quo of coalmine in china, different existing analysis and measures discussed for the safety problem solution of coalmine china. With the consideration of system thought in mind, the author present with a unique systematic reason analysis method on such actuality--individual analysis and general analysis--each for its particular purpose. Upon such cause analysis, construction of the safety system is made clear and, solutions for such problems provided.

Jan 1, 2006

By J. B. Hanlon

In order to protect coal mine owners, operators, and lending institutions from potential environmental liabilities, responsible parties must maintain a thorough understanding of the environmental disposition of the property they control, and the ramifications of impending laws and regulations. The best way to accomplish this is to periodically conduct a Phase I Environmental Audit. The systematic approach of an audit will reveal areas of DOD compliance with SMCRA and EPA regulations which the coal owner and/or operator will be able to use to correct deficiencies and prevent the occurrence of conditions which could lead to permit block, fines, and ultimately reduced productivity.

Jan 1, 1995

By Frederik P. Agterberg

During the past 20 years, methods of multivariate statistical analysis have been developed on mainframe computers for the integration of geological, geophysical, geochemical and LANDSAT data in mineral resource appraisal. At present, it is becoming increasingly feasible to perform mathematical image analysis of digitized patterns on microcomputers. This has led us to develop a new method of statistical pattern integration for mineral exploration. In this paper, the new method is used to outline, by means of posterior probabilities, exploration targets within small areas of which the prior probabilities for occurrence of new mineral deposits had been estimated by multivariate analysis.

Jan 1, 1989

By Deepak Malhotra

The economic viability of mineral companies not only depends on maximizing mineral recoveries but also on their ability to do so at minimum cost. Increasing pressure to cut costs has resulted In reduced staff, thereby decreasing the capabilities of routine metallurgical audits. This paper reviews a systematic approach to plant auditing which has been used successfully at several operations. Several case studies illustrating the potential benefits that can be attained from flowsheet auditing of mineral processing plants are discussed.

Jan 1, 1991

By Mayank Srivastava, Satya Harpalani

Production of methane is an inevitable consequence of mining coal. Although the number of mines practicing recovery of methane prior to, or during, coal mining is increasing, ventilation air methane (VAM) is still a significant source of methane addition in to atmosphere. Recent studies have shown that there are ways to recover the VAM energy, while simultaneously reducing the methane emission in to atmosphere. This paper discusses a case study, currently underway, to develop a technique to quantify the VAM emission from a mine. It also presents the different VAM utilization techniques and the suitability of one for the mine being studied. Finally, the paper summarizes the research issues that require further investigation.

Jan 1, 2005

By Frank F. Rahne

Butler Taconite, operated by the Hanna Mining Company, is an Iron ore pelletizing operation that is located on the Western end of the Mesabi Iron Range in Northeastern Minnesota. The operation mines low-grade taconite ore and through primary crushing, two stage grinding, magnetic separation, agglomerating and indurating, produces 2.6 million annual tons of high quality, 66% iron pellets. Mining and stripping is done with 13 - M100 trucks and 5 - 12 cu. yd. shovels. The operating processes in the concentrator and pellet plant are primarily con¬trolled through a centralized control room and monitored by a PDP l140 computer. During 1969 and 1970, a re-organization of the Company took place. Through this re-organization, each mine unit was analyzed and studied to determine the proper staffing of the internal departments. At this time, it was decided to continue with further detailed studies of the Maintenance Department with the intent to reduce maintenance costs. Maintenance costs at the time of the re-organization were 38.6% of the total mine operating cost. The preliminary study indicated that the Maintenance Department had a system of maintenance, as a matter of fact, it had a separate system in each sub-maintenance division and in some of the sub-divisions each foreman had a system of his own. Therefore, from the data collected, it was decided to develop one system of maintenance that could be utilized throughout the entire operation. To determine the type of system suitable to all phases of the operation, detailed time and method studies were conducted. All types of maintenance tasks performed at the operation were studied. The data collected was analyzed and the recommended improved methods were reviewed with the Maintenance Superintendent and his staff. The new improved methods that were accepted as feasible, were introduced into the system immediately.

Jan 1, 1975

By Donald E. Scheck

Blasting practices based on sound engineering principles are well established but the successful application of these practices requires accurate information about the overburden geology and close supervision of the drilling and blasting operations. Good design alone is not sufficient to insure good results, but the process may be difficult to control unless steps are taken to measure the variables and to provide management and the operators with the information they need to establish and maintain control. Satisfactory blasting can be defined as loosening and fragmenting the rock so that it can be handled by the excavating equipment, while at the same time, governmental regulations on air blast and ground vibrations are not violated. Optimum practices achieve these objectives at the lowest combined cost of the drilling and loading operations and the blasting materials. Total system optimization, that is, taking into consideration the effect of fragmentation on the cost of operating and maintaining excavating equipment as well as drilling and blasting costs, probably is not a reasonable goal at the present time.

Jan 1, 1984

By T. P. Weldum, B. J. Mahoski, R. S. Rasmussen

A case study of a systematic approach to grinding circuit steady-state optimization is presented. After an overall review of the flow-sheet, two operating circuits were prepared for detailed testing. Functional performance analysis was chosen as the primary modeling system, and, on this basis, a quality-assurance program for data gathering was implemented. A number of circuit-design and operating variables were investigated. Statistical analysis of plant-test results revealed relationships previously unquantifiable by any other modeling technique. Improvements in the classification system and in mill grinding efficiencies were demonstrated. As a result, there was significant energy cost savings.

Jan 1, 2000