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By Ellen Amoako Afful, Michael Moats, Guang Xu, Ashish Kakoria

Electrowinning and solvent extraction are crucial steps in the production of high-purity copper. However, safety concerns have been raised regarding the acid mist generated from the electrowinning process. The mist generated results in health risks to workers and damage to machinery and infrastructure. Currently, chemicals and pellets are used to control acid mist. However, the effectiveness of these controls may vary depending on the type of organic solvent used in the solvent extraction process, which can influence the generation of acid mist. This study aims to evaluate the impacts of organic solvents and surfactants on acid mist suppression. In this study, an electrolyte is contacted with organic solvents to simulate the solvent extraction. The electrolyte is dosed with 20 mg/L of surfactant at each contact. Acid mist testing is performed on the electrolyte separated from the organic phase at the end of the solvent extraction step. The mist collected is analyzed to determine the level of acid mist generated. The results of this study indicate that organic solvents and surfactants showed significant acid mist suppression, but with somewhat different suppression efficiencies. After first contact, Licorice and the organic, for instance, showed a suppression efficiency of up to 69.7% but its efficiency gradually decreased as the number of contacts increased.

Feb 1, 2025

By M. D. Flavel

My paper relates to bond's third theory of comminution and suggests work be used as a basis for designing crushing and screening plants, this will give more accuracy than existing methods, As stated in the abstract, this paper is only a synopsis of my official paper, many of the questions that might arise in this brief address will be answered by referring to the detail i n the main paper $ Because of the limited time available and the fact that many people here do not need to study the aspects of crushing and screening in depth, i will highlight-those sections of the paper which show how major capital, operating and energy cost savings can be achieved in the process, I will develop the theme in the following manner, Firstly, pointing out, why a new approach is needed to the fundamentals of crushing and screening, Secondly, by setting forth some theory to describe what we are trying to accomplish, Thirdly, by looking at important factors which need to be observed in designing plants and applying machines to comply with this theory, Lastly, i will put forth some ideas on how we might develop this theory to make the industry more efficient, At the outset, i have to say my approach to this process is entirely new, for those used to applying machines and designing plants on existing criteria, they will find this theory easier

Jan 1, 1977

By D. M. Neil

Road-headers are one of the most popular mechanized excavators used in mining and civil under-ground construction. These machines are primarily used in soft to medium hard rocks. This paper reviews the parameters associated with the application and operation of road-headers and presents a method for estimating cutting performance.

Jan 1, 1994

By Christoph Mueller, Grzegorz Tabak

Basing on five years of experience, this paper discusses modern e-drive systems used in underground transport. This covers Energy distribution and cabling principles, inverters and motors as well as auxiliary aggregates. Also an overview of different regimes for battery charging and the energy management and the method of control of the traction are lined out: This means that throttle and brake are not handled separately, but integrated into “longitudinal control” algorithms which assure that a commanded speed is maintained while synchronizing the multi motor systems and taking into account the constraints imposed by e.g. slope grade and battery parameters.

Jun 25, 2023

By Klimpel. R. R.

Acknowledgments I am honored to be named as a recipient of the Antoine M. Gaudin Award, and I would like to briefly single out four groups who deserve a special thank-you relative to this award. The first group consists of Professor Kawatra, the many international support references that he gathered and the Gaudin Committee itself. I know such things don't come without considerable effort by many individuals, and I'm grateful for their support. The second group consists of the management of The Dow Chemical Company, the managements of various mining companies and, in recent years, the management of G. S. Technologies, all of whom supported me, financially and otherwise, in my grinding, flotation and other particle-processing work. Operations people are the most overworked and under recognized people in the world, whether they be in the mining or chemical industry. Obviously, without extensive industrial support, especially from operating personnel in the mining industry, almost nothing about the work contained in this lecture would have, or could have, happened. The third group consists of a number of coworkers who have played key roles in specifically implementing the new flotation-product portion of this lecture. Of these, Bob Hansen, Don Leonard, Basil Fee, Simon Isherwood, Fernando Cones and Marty Meulendyke deserve special recognition. They have not only been dedicated, but they have been great to work with. Also in this third group are many members of the international academic community, especially those at Penn State. Professor Leonard Austin must be singled out because he took me as a young mathematically oriented chemist and taught me to be an effective process-oriented engineer. Without this experience, I would not have had the over 30-year career as an engineer, which I have loved. In addition, Len planted the size-reduction-research virus in my blood, which I can't seem to get rid of. I also need to mention Professor Frank Aplan, whose obvious love of mineral processing and froth flotation helped to create my interest in flotation. Thus, for those of you who don't like my approach to flotation, it's all Frank's fault. The fourth, and certainly not the least, group to thank is my wife, Charlene, and our two sons, Richard and Steven. No one could have a more supportive family. In every sense of the word, my wife has been my partner from the beginningwe were married at the end of my freshman year in college. She has sacrificed much for me, and I will never really be able to express the depth of my gratitude for Charlene's encouragement, loyalty and support over the past 36 years. General comments on froth flotation The industrial process of froth flotation: Where is it going? I'm here to tell you loud and clear that froth flotation is alive, well, and growing. The inherent characteristics of high mineral throughput per unit of capital, low operating cost per unit of feed, high mineral specificity and high operating flexibility have guaranteed froth flotation an important past and a growing future. As with any evolving technology, there are always trends at the industrial level that are primarily driven by economics. The current trends include: •the movement towards larger and larger equipment, •more alternative equipment designs (e.g., the column cell),

Jan 1, 1996

By P K. Kaiser, D A. Malovichko

Highly stressed excavations in hard brittle rock may fail by self-initiated, triggered or dynamically loaded strainbursts (Moss and Kaiser 2021). The low-frequency part of seismic radiation associated with strainbursts is described by a crush-type seismic source mechanism with a significant negative (implosive) isotropic component and a ‘pancake-shape’ CLVD deviatoric component. The seismic source is co-located with the excavation damage site. For such strainbursts, the ejection velocity is primarily related to the depth of strainbursting, the rock mass bulking characteristics, the duration of the bulking process, and the effectiveness of the support system. For dynamically loaded strainbursts, the displacement and energy demand may be augmented by the impact of the stress wave from a distant seismic event. This article describes the failure process and factors contributing to rock deformation and energy demands for support design. Case examples are used to demonstrate the dependence of rock displacements, rock ejection and energy demand on the factors described above. A seismic source model is proposed to assess the depth of strainbursting and the duration of the related bulking process by using seismic monitoring data. The implications for support design are briefly discussed.

Apr 26, 2022

By Yi Luo, Jian Yang, Hua Jiang

Surface subsidence induced by underground coal mining activities, especially longwall mining operations, can cause various problems to interstate highways ranging from structural integrity, drivability to safety. Accurate subsidence prediction, correct influence assessments, and effective mitigation measures are the keys to ensure the safety of highway traffic. The surface subsidence prediction program, called comprehensive and integrated subsidence prediction model (CISPM), was developed based on the principle of influence function method and has been validated with a large number of subsidence measurements. In this paper, the techniques to use the predicted final surface movements and deformations for assessing their influence on the integrity and functionality of highway structures (e.g., road surface pavements, concrete slabs, transverse joints, etc.), vehicle dynamics, comfort level, and drivability are presented. A number of mitigation measures to protect the highway structures and to ensure traffic safety are proposed along with an application case.

By Donald P. Schlick

Gentlemen, today I would like to talk to you about metal and nonmetal mine health and safety--past, present and future. Briefly, I will comment on the past because it is important to an understanding of our present activity and our plans for the future. Federal inspection of noncoal mines was not authorized until 1966, when congress passed the federal metal and nonmetal mine health and safety act; public law 89-577, with the passage of this act, the federal inspector, for the first time, had the delegated authority and responsibility to enforce health and safety regulations designed to prevent personal injuries and occupational diseases, the new law also provided for the education and training of our miners; assistance to the operator through the transmission of technical and scientific information and assistance and equally important, the law made provision for state participation in the congressional mandate to prevent injuries and save lives in the mineral industry, Before I tell you about our program and our future plans, I want you to know that I am here to listen as well as to talk! In my view, the only kind of communication that is meaningful is two-way communication. Our nationwide progress in metal and nonmetal mine health and safety during 1972 cannot be measured in reduced fatalities or injuries. The unforeseen tragedy that took pace in Kellogg, Idaho, in may of last year mode that almost a certainty.

Jan 1, 1973

By John B. Rigg

Thank you Mr. Chairman. It was a generous introduction. It allays some of the puzzlement I have of being a minority among the speakers at this conference. I see from the program that only two of us have been asked to speak on topics in keeping with an election year. Instead of reporting facts on past events as most speakers are, J. W. Wilson, of Consolidation Coal, and I have been designated to forecast the future. Forecasting in an election year implies a liberty to fabricate at will, hallucinate, fantasize, stretch fact and fancy and generally prognosticate without regard for the consequences. Since I'm not seeking your votes, promises aren't mandatory. This will be done with supreme confidence stemming from profound wisdom and a foolproof crystal ball. So instead of soliciting your vote, I'll simply penetrate 24 years of tomorrows, which may not be much different than some of us remembering the later hours of last night. My remarks do not draw upon Gulf planning department projections. Instead they are a roll of the dice of personal conjecture to stretch your imaginations on oil shale mining through the year 2000. In this regard, it is sobering to keep in mind that it has been in my lifetime that investors wouldn't risk a dollar on paperback books, motels, supermarkets, or drive-in restaurants. And only thirty years ago it was predicted by an eminent Ivy League professor

Jan 1, 1976

By T. Vandergrift, J. Sturgill, W. Gerhard, J. Carrick

As surface minable coal is depleted, many operators look to high-wall mining to extend reserve life. Recent advances in highwall mining equipment have greatly improved productivity, clean coal recovery, and attainable penetration beneath the highwall. Somewhat lagging have been systematic design approaches for ensuring web pillar and overall highwall stability. This paper presents an overview of the design, planning, and field performance of a multiple-seam highwall mining application in southwest Wyoming. The safety and efficiency obtained to date is attributable to the careful geotechnical and operational planning described herein. Field confirmation of performance and suggestions for improvement are also discussed.

Jan 1, 2004

The Bagdad mill, built in 1977, was de-signed for a mill capacity of 36,300 tpd. An ABC (Autogenous Mill-Ball Mill-Crusher) grinding circuit was chosen. The original mill contained three completely independent grinding circuits, each containing one 9.75 m diameter by 3.96 m long fixed speed autogenous mill, one 4.72 m diameter by 6.71 m long ball mill and one 2.13 m diameter short-head cone crusher. Total installed power per grinding circuit was 8,464 kw with 5,966 kw in the autogenous mill, 2,237 kw in the ball mill and 261 kw in the crusher. (See FIGURE I--Major Equipment Flow Diagram.) The autogenous mills were designed to be able to operate semi-autogenously but were never converted to SAG. As a result of this design, only about 4,100 kw of the designed power is utilized in the autogenous mills. The grinding circuits are closed with 2.44 m by 6.10 m double deck vibrating screens. Screen oversize is returned, by a series of conveyors, underneath the mill coarse ore stockpile to feed the crushers. Variable speed belts feed the crushers and control power draw. Crusher product reports directly to the tail end of the autogenous mill feed belt. (See FIGURE 2--Typical Crusher Feed and Product Size Distributions.) Tramp iron in the autogenous mill-crusher circuit is handled in a unique way. A magnetic sensor detects the metal. This closes a gate which directs the crusher feed onto a separate belt which bypasses the crusher and returns the material to the autogenous mill feed belt.

Jan 1, 1992

By Keith E. Dyas, John Nelson, Ronald T. Johnson

GENERAL DESCRIPTION The Bruce mine of Cyprus Mines Corp. is located in Bagdad, AZ. The mining method used is open cut-and-fill. Of the annual production of 81 647 t (90,000 st), approximately 83% is taken from load-haul-dump (LHD) stopes and the balance from slusher stopes. All ore is produced from the area between the 1250 level and the 2300 level. The average travel time from the shaft pocket to the stope is approximately 5 min. GENERAL ORE BODY REQUIREMENTS AND LIMITATIONS Size, Shape, and Dip The Bruce ore body occurs in quartz-sericite schist with Dick rhyolite on the footwall and andesite on the hanging wall. Diabase dikes are found in the hanging wall; there is also a dike coming off the footwall and crosscutting the ore body. All of the rock types are of the Precambrian Yavapai series and have been subjected to regional metamorphism. A composite of the ore body is given in Fig. 1. The deposit is of massive sulfides occurring as a steeply dipping replacement body. On the upper levels the ore is veinlike with widths from 0.6 to 4.6 m (2 to 15 ft), dipping at 1.4 to 1.5 rad (80° to 85°). On the lower levels the ore is dipping from I to 1.2 rad (60° to 70°) with widths from 3 to 16.8 m (10 to 55 ft). The strike length varies between 107 to 183 m (350 to 600 ft). The rhyolite footwall generally has a knife-edge contact with the massive sulfides. The exceptions to this are the upper levels where there is a 1.5 to 3 m (5 to 10 ft) band of silicified sericite schist between the sulfides and the rhyolite. In the southern part of the ore body the hanging wall is tuffaceous andesite and andesite. In this area the contact is generally sharp and easy to follow. However, to the north there is a large chlorite schist zone that crosscuts the bedding and comes in contact with the massive sulfides. This is apparently due to hydrothermal alteration of the andesite. The chlorite schist is highly mineralized with chalcopyrite and pyrite and quite often forms economic pockets of ore. In the massive sulfides the chief ore minerals are sphalerite and chalcopyrite. Pyrite is the predominant sulfide with considerable pyrrhotite throughout. Bright arsenopyrite ouhedrons in fine grain massive sulfides are quite common. Occasionally small amounts of galena are seen, usually near the foot or hanging wall contacts. On rare occasions tennanite is associated with massive arsenopyrite. Minor amounts of quartz, calcite, and un¬replaced remnants of sericite schist occur, but essentially pyrite is the gangue in which the ore minerals occur. The ore values are in excess of 3.5% copper and 12.5% zinc with some silver and rare gold as byproducts. Ground Conditions The massive sulfides are generally self-supporting. One exception is in the 1850 stope where the ore body is 9 to 11 m (30 to 55 ft) wide and 152 m (500 ft) long. There are flat to shallow dipping slips and seams in the ore, creating extremely blocky ground. For support, old 25.4-mm (1-in.) hoist ropes were installed tensioned to 27 t (30 st), and then cement grouted over the entire length in longholes [14 to 15 in (40 to 50 ft) in length) drilled on 3-m (10-ft) centers from the level above. This has tied the formation together very successfully and virtually eliminated the blocky ground condition. Both the hanging wall and footwall are quite shaley in some areas. Reasons for Adopting Trackless Open Cut-and-Fill Methods First, any method other than open cut-and-fill would have caused too much dilution. The use of rubber-tired mining equipment in the pro¬duction stopes requires a footwall ramp. The inclines in ore will be mined out, so this ramp in the footwall will provide access to and from the stopes (Fig. 2). This incline is very expensive, but necessary to convert existing stopes to LHD mining. 'The final cost of ore mined by the LHD machines has not been determined. As of 1972, tons per manshift in the 2150 stope-the only one to complete a full cut-had increased from 7.58 t (8.36 st) to 12.83 t (14.14

Jan 1, 1982

By J. Lovering, H. Wilhelm, P. Siewert

Introduction The Afton property is located 290 km (180 miles) by air east-northeast from Vancouver and 14 km (8.7 miles) west of Kamloops, a city of 60,000 people, in south central British Columbia, Canada. The mine is adjacent to the Trans-Canada Highway at an elevation of 670 m (2198 ft) above sea level. The ore body is a porphyry copper deposit that has undergone supergene alteration. The major economic minerals in the supergene zone are native copper and chalcocite with chalcopyrite and bornite in the hypergene areas. The grade is 1% with an overall copper distribution - 70% native, 25% chalcocite, and 5% chalcopyrite with bornite and covellite. The ore also contains important but variable amounts of gold and silver. The mill was designed to treat 6350 t/d (7000 stpd). Semiautogenous grinding was selected to minimize capital cost and because of the expected high clay content of the ore, which would have caused problems in a conventional crushing and screening plant. Test work indicated that a recovery of 87% was possible in a circuit incorporating both flotation and gravity separation. Flowsheet Run-of-mine ore is crushed in a 1.06 x 1.65-m (3.5 x 5.4-ft) Allis Chalmers gyratory crusher set at 228.6 mm (9 in.), closed side setting. The surge pocket, below the crusher, is emptied by a Hydrastroke feeder onto number one conveyor, which discharges onto a 180,000-t (198,416-st) coarse ore stockpile. Six Hydrastroke feeders on two conveyors withdraw the crushed material from the bottom of the pile. These two conveyors, in turn, discharge onto the belt feeding the semiautogenous mill. The live storage in the stockpile is approximately 22,000 t (24,250 st), sufficient for three days' mill feed. Primary grinding is accomplished in an 8.5-m (28-ft) diam by 3.7-m (12-ft) long Koppers (Hardinge Cascade) mill (Fig. 1) containing a 10% ball charge and driven by a 4000-kW dc variable speed motor. The mill dis¬charge is pumped by a 10 x 12 G.I.W. pump to a 1.22 x 4.88-m (4 x 16-ft) stationary screen sloped at 20°. Screen oversize returns to the semiautogenous mill (SAM), and the undersize flows by gravity to the ball mill discharge pump box. Secondary grinding is performed in a 5-m (16.4-ft) diam by 8.84-m (29-ft) Koppers overflow ball mill driven by a 3430-kW synchronous motor through an air clutch. The mill is in closed circuit with a Krebs Cyclopac containing 10 635-mm (25-in.) cyclones and the cyclone overflow, at 35% solids and 65% to 70% -200 mesh, is flotation feed. In order to limit the buildup of native copper, circulating in the secondary grinding circuit, a portion of the underflow from the cyclones is processed in a circuit containing screens, cyclones, and shaking tables to produce a finished metallic copper concentrate. Primary mill variable speed drive The overall waste to ore ratio at Afton was 4.5:1. The mining was to be done with only three shovels, which meant that it was highly unlikely that more than one of them would be in ore at any one time. The resulting inability to blend the mill feed made it impossible to prevent wide swings in the grade and grindability. The variable speed do drive motor installed on the semiautogenous mill was selected because of the extreme variability of the Afton ore body. This variability has persisted throughout the lifetime of the mine. There are times, however, when due to ore conditions, the mill is operated at full speed (78% of critical) for extended periods of several shifts duration. There are other times when the mill speed may be changed several times in a 12-hour shift due to changing ore conditions. When ore is processed that contains a fairly large proportion of fine native copper, the primary mill speed and, consequently, the tonnage may be reduced to improve the secondary grind and to maintain an acceptable grind and recovery. High clay ores require less mill speed and more dilute grinding densities. In the latter case, the slower primary mill speed also helps to minimize damage to the mill liners. Approximately 57% of the time the mill operates between 90% and 100% of full speed or between 71% and 78% of critical. The variable speed is also used for inching during mill relines.

Jan 1, 1987

By J. D. Cooper, D. W. Thompson, J. Basiuk, W. Cass, R. Ilves

The Department of Thoracic Surgery and Pathology at the Toronto General Hospital have had a long standing interest in the early detection and treatment of carcinoma of the lung. Our initial experience was with a population at risk due to a prolonged period of cigarette smoking. More recently our efforts have turned to industrial exposure, specifically in the nickel and uranium industries. [Initial Screening Project] (1) For a three year period 1963 to 1966 a cytology screening program was carried out through the Out-Patient Department. The study was limited to cigarette smokers over 40 in age. A total of 1586 patients were examined. Of the sputa collected, the classification is seen in Table 1. There were 11 malignant sputa present. Added to this number were 25 patients with symptoms, normal chest X-rays, but malignant cells on cytology, and a further 5 patients in whom an abnormality (eventually proven non-malignant) showed on X-ray, and sputum showed malignancy which was radio logically occult. (Table II). This gave a total of 41 patients with malignant sputum who were evaluated between 1960 and 1966. The clinical course of these patients is seen in Table III. Only 19 of 41 patients had localization and treatment of their tumour during that study period and this low rate of localization attests to the technical difficulties endoscopy in that day presented. The method of localization was as follows: a) 6 patients showed an area of segmental pneumonitis somewhere in this time period b) Using the rigid bronchoscope localized the tumour in 9. This was proven by direct biopsy, and frequently required more than one bronchoscopy over a prolonged time period. c) bronchograms and tomograms showed abnormalities in 5 patients. Of these 19 patients, 5 were treated by radiotherapy because of general condition or refusal of surgery. Three of the irradiated patients died of recurrent cancer within three years. The other two died within one year of unrelated disease. Fourteen patients underwent resection, with one operative mortality. At pathology, the tumours were "in situ" in 6 and invasive in 13. There was no evidence of nodal spread. When last followed up in 1979, there were no cases of recurrent tumour and no cases of second lung primary tumours. Similar experiences have been reported from the Mayo Clinic (2), Johns Hopkins (3) and Memorial Hospitals (4). Early detection of radiologically occult tumours which are in situ or minimally invasive has given uniformly good results. There have been no deaths from recurrent or metastatic cancer in surgically resected patients, and only one second primary tumour has been detected. Interestingly, the Hopkins group reports that 5 patients with Stage I squamous cell tumours refused operation. One refused any treatment and died of disease at 12 months. Three were radiated, and were alive from 14-38 months post-treatment, all with evidence of recurrent disease. [Sudbury Sintering Plant Study](5) From 1948 to 1963 an open travelling-grate sintering process was employed to convert nickel sulfide to nickel oxide at an International Nickel Company operation. The environment in this plant was particularly dusty and filled with fumes. It became apparent by 1969 that the incidence of bronchogenic carcinoma was markedly increased in workers from this plant. A concerted effort was made to track down all workmen with this exposure. During 1973 and 1974, 268 men were studied. Chest radiographs were done and showed no mass lesions. Sputum was collected on three consecutive days and analyzed. There were 12 men with malignant sputum, all of the squamous cell variety. Two refused any investigation, one presenting 31/2 years later with extensive hronchogenic carcinoma, and the other 5 years later with extensive carcinoma of the maxillary sinus. In the remaining ten patients careful rhinolaryngeal examination as well as a detailed bronchoscopy, involving examination, brushings and biopsy of all pulmonary segments was carried out. One patient was found to have laryngeal carcinoma and was treated by radiation. In nine patients, the malignancy was localized to the lung, leading to six lobectomies, two pneumonectomies and one sleeve lobectomy at operation. However, the follow-up in these cases suggests a different biological behaviour with these industrially related tumours. While no tumour has recurred locally, one patient has died of metastatic cancer and two patients have developed second and one patient a third pulmonary primary cancer. However, survival has still been much better than wits radiographically manifest lung cancer. [Technique of Localization] (6) Following a careful rhinolaryngeal examina examined and then the lower respiratory tract is examined. This is all performed under general anaesthesia. The trachea is examined with the rigid Jackson bronchoscope, collect-

Jan 1, 1981

By Amila Sandaruwan Ratnayake, T. Dilmi. U. Wijewardhana, H. C. S. Subasinghe

The value addition potential of ilmenite was examined using several characterization techniques. Raw ilmenite is composed of 93.65 wt.% of FeOTiO2, 3.55 wt.% of SiO2, 1.22 wt.% of Al2O3, and the remainder being other minor oxides. Ilmenite and powdered carbonized coconut shells were mixed in the weight ratio of 4:1. A separate fraction of the same mixture was added with powdered seashells in the weight ratio of 4:1:0.5. Six fractions of each mixture were distinctly milled from 1 to 6 h in a planetary ball mill. XRD spectra (broadened and diminished reflections of ilmenite) and FTIR observations (Ti―O―Cbonding) of milled samples indicate the possible incorporation of carbon into the ilmenite structure. Any clues of an occurrence of new rutile peaks were not observed in XRD spectra of milled samples. Consequently, the carbothermic reduction has not been initiated during mechanical activation. In this case, samples powdered for 6 h in a mill were isothermally annealed for 2 h under normal airflow at temperatures of 800 °C, 1000 °C, and 1200 °C, respectively. According to the X-ray diffractograms, the annealing temperatures of 1000 °C and 1200 °C exhibited almost similar trends with rutile (R), pseudobrookite (PB) and elemental iron (F), and a very few ilmenite (I) peaks. Consequently, 6 h of milling and 1000 °C annealing were concluded as the optimum conditions for the carbothermic reduction. Moreover, this study indicated seashells as a potential rate raiser for the carbothermic reduction of ilmenite at 800 °C. Therefore, this process is applicable to upgrade ilmenite into a mixture of synthetic rutile and elemental iron.

Mar 29, 2021

By C. G. Tester

Automatic tripper control systems can be reliable and as such are suitable for use in the mining industry. Proper application of fundamental engineering principles provides the means for the reliability. Some of the principles are: (1) Be sure the system designer designs a system that does the job operations people want done; (2) Use sound logic design practices to avoid internal electrical problems; (3) The design must be maintenance oriented; and (4) Use good quality components. I would like to discuss a tripper control installation at Kennecott Copper Corporation, Chino Mines Division, in Hurley, New Mexico, and how these principles apply to this tripper control system. First, however, I will expand on the principles to clarify just what is meant. First, "Be sure the system designer designs a system that does the job operations people want done.? Operator acceptance is often the key to the success or failure of an automatic control system. One of the best ways I know of to get operator acceptance is to give him a system that he wants. I don't mean to imply that if bad practices or procedures exist that they should be incorporated in the control system. I do think that many designers feel they haven't done their job if the control system doesn't do things drastically different than the old manual method. Good engineering principles dictate that the job should be done right and if the manual method was right it can very likely be right for the automatic method.

Jan 1, 1973

By Robert E. Murray

It's indeed a pleasure for me to speak to you today about the development and operation of large-scale surface coal mining projects in the western United States. It is an exciting story about American business working to solve a critical national problem -- the energy shortage -- through research, new technologies, financial innovation, and imaginative management. The North American Coal Corporation -- the second largest independent mining company and ninth largest United States coal producer -- is proud to be a part of this story. Our operations in North Dakota reflect the coal industry's Western activities. So, today, I would like to focus on our planned involvement in that state. I'll briefly survey why North American is developing large- scale surface mining in North Dakota, and I will outline the many problems associated with this coal development and how we are working to solve them. Finally, I will look at the financial and management techniques we are using to make it all work. In short, I'm going to present a case study of Western coal mining. Let's begin by looking at the reasons we are in North Dakota. The United States Bureau of Mines estimates that 44 per cent of the nation's total recoverable coal deposits underlie the three Northern Great Plains States of North Dakota, Montana, and Wyoming. We estimate that North Dakota alone has about 25 billion economically surface-mineable tons of coal with today's technology. North Dakota has the energy that could keep our factories running and our homes lighted In the years ahead.

Jan 1, 1975

By J. J. Casey

This paper is one of a series of presentations organized by the Conference of American Society of Civil Engineers with the goal of making significant progress toward an equitable and effective allocation of risks in construction undertakings among the principal parties - owner, contractor and designer. The role I have been assigned is principally one of identification of risk while others will devote greater attention to the allocation of these risks and the contractual arrangements necessary to properly make these allocations. Construction projects are joint undertakings by parties who bring different skills and interests toward a common effort, much as this conference does. A project is not an adversary proceeding and does not benefit from establishment of an adversary mode, as our lawyer friends seek in the resolution of legal issues. Accordingly, I urge upon this Conference the adoption of two basic precepts and guidelines as the criteria for sharing of the risks inherent in construction undertakings toward achievement through mutual effort the common goal of a successful project completed in the shortest time and at the least overall cost. These precepts are: (1) that all risks are rightfully the owners unless transferred to or assumed by another party for a fair compensation; and (2) that the principle guideline in determining whether a risk should be so transferred should be whether the receiving party has both the competence to fairly assess the risk and the expertise necessary to control or minimize it. The sponsors of the conference have provided certain guidelines to the authors. There is, however, no constraint in expressing one's bias and I suspect that my contractor's outlook may be inherent in my comments. The guidelines have suggested that I indicate whether the risks identified are ones that can or should be shared or borne by one party alone. In doing so, I will attempt to follow the precepts I have recommended.

Jan 1, 1979

By F. Varley

Researchers from the National Institute for Occupational Safety and Health (NIOSH), in cooperation with mine operators, conducted a study of heat stress exposures among mine rescue workers in underground mines. Mine rescue workers face extreme heat loads as they enter hot and poorly ventilated environments, particularly when they are wearing breathing apparatuses. The burden of wearing a closed-circuit breathing apparatus (CCBA), the inability to drink fluids for extended periods of time, and the potential for ventilation disruptions and fires combine to increase the risk of heat illness during a response to an emergency. In this research, ambient environmental conditions and heat strain indicators were measured using conventional ventilation monitoring tools during mine rescue training exercises. Heat strain was measured with an ingestible temperature-sensing pill that measured core temperature continuously. In addition, a heart-rate monitoring chest strap was used to indicate physical strain resulting from physical activity and heat. Both core temperature and heart rate data were trans-mitted to a remote recorder worn by a rescuer and time-stamped. Team activities were also observed to determine the contribution of work rate to a person’s total heat load. The effectiveness of several engineering controls, such as cooling the air inhaled by rescuers through an apparatus, wearing cooling vests, and supplying water through the CCBA masks, were investigated. Administrative controls, such as limiting the duration of exposure and controlling the work rate through forced-rest regimens, were also evaluated. Results to date are discussed, and tools for evaluating team condition and estimating the length of time it would be safe for rescuers to work are proposed.

Jan 1, 2004

By A. Dell’Era, E. Ciro, C. Lupi

The indium recovery via electrowinning from sulfate baths has recently gained significant attention as it does not present toxic emissions, hermetically sealed system requirements, human health, and environmental hazards. Following previous works related to the optimization process for AISI 316L and Ni cathode, it was observed significant importance of the metal supports on the input and output parameters of the indium electrowinning process from sulfate solutions. Thus, comparing input and output parameters in both cases seems very interesting. Particularly, regarding the input parameters, the attention has been focused on the electrolyte composition, current density, and temperature, while productivity, morphology, and structure have been considered regarding the output parameters. Considering the productivity as the optimal output, the findings for Ni cathode were better than that for AISI 316L in most of the selected conditions studied. In the case of morphology, indium grains appear rounded and dendritic on the AISI 316L, while those on the Ni cathode show stratified lamellar grains. Anyway, the indium deposit obtained on Ni cathode shows bigger grains independently from the used operative conditions with respect to that on AISI 316L. Regarding the structure, it is clearly tetragonal, but preferential orientation, crystallinity, and deformation of the structure strongly depend on the metal support.

Jun 14, 2023