Search Documents

In the grand scheme of things, the 9.5-t (21,000-lb) shipment of molybdenum concentrate that left Freeport-McMoRan?s Climax Mine site on May 10, 2012 was not unlike the thousands of others that have been hauled away from the site during the last century, except for the fact that this shipment marked the official rebirth of one of America?s greatest mines. For nearly two decades, 17 years to be exact, there was no production from the mine that was once the largest underground mine in the world and was so important to the Allies? effort during World War II that it was assigned the highest priority of any mine in the United States by the War Production Board. The economic recession in 1980 put an end to the mine?s success, and the Great Recession of 2008 nearly derailed the mine again. But, like the nearby town of Leadville, CO, the mine survived thanks to an investment of more than $700 million by Climax Molybdenum Co., a Freeport-McMoRan company, to bring the Climax Mine back into production.

Jan 1, 2012

By William Gleason

"With desert temperatures climbing high at Caterpillar’s Tinaja Hills Demonstration and Learning Center near Tucson, AZ in September, a group of editors were given a reprieve from the sun and stepped inside the new Cat Minestar Command Center. The movie theater-like temperatures inside were a welcome relief, and the computer screens stationed around the room were an indication of not just how much things have evolved in the mining equipment sector, but also a peek into the future of where mining is headed.Equipment manufacturers like Caterpillar have always had to deal with peaks and valleys in demand that come with mining, perhaps never more so than in the last five years. Sudhanshu Singh, global product manager for Caterpillar, said that in one month in 2012, at the height of the mining Super Cycle, Caterpillar produced more than 150 large mining trucks (haul trucks that carry 136 t/150 st or more). By contrast, Caterpillar produced about 80 of those trucks in the full year of 2016. Between 2012 and 2016, Caterpillar saw its profits drop by 40 percent.“This shows how cyclical the industry is, and it is a testament to the strength of Caterpillar to be able to tolerate the wide swings,” said Singh. Demand for commodities is once again on the rise as are commodity prices with many signs pointing toward a recovery for the mining sector, and Caterpillar has positioned itself for the recovery. During its 2017 press event in September, company officials emphasized that Caterpillar has added strength in its technology divisions by forming new partnerships and adjusting its operating plan.“At the heart of our enterprise strategy is the operating & execution (O&E) model, a strategic framework to identify areas of the business that either create or consume the most value,” said Caterpillar chief executive officer, Jim Umpleby. “Using the O&E model as a guide, we gain a deeper understanding of where we have a competitive advantage, which is key to generating high returns.”"

Jan 11, 2017

By Greg Beckstrom

Minnesota is a major mining state. This statement is not a dream or stretch goal but is a fact. As reported in a recent edition of Mining Engineering magazine, Minnesota ranks as the third largest state in terms revenues generated from nonfuels mineral production. The vibrancy of the mining sector in Minnesota can be attributed to several factors. The northeastern corner of the state is home to Minnesota?s iron range, one of North America?s largest deposits of iron ore. Iron ore from Minnesota is a strategic resource that has been [ ] instrumental to the nation?s development ? 90 percent of the iron used to build ships and planes during World War II came from Minnesota. Taconite pellets now produced from openpit mines on the iron range are shipped to steel mills worldwide. The growing appetite for steel in China and India has reignited once moribund mining operations throughout the iron range.

Jan 1, 2012

By Stig Premfors

Lamco Joint Venture is operating a Dravo Pelletizing machine to produce pellets from the natural slimes of an earthy hematite ore. The grate area of the machine 3.3 x 106 m equal to 350 m2 (3800 sq. ft.) and the installed fan capacity is 8200 HP. The limiting factor for production is normally fan capacity. This means that the processing fans can not pull the additional air (i.e the additional calories or BTUs) through the bed which would be required for increased production. A way to increase production without major modifications is to supply the additional calories needed for increase production by adding coal to the pellet feed. After successful laboratory tests following method of coal addition has been chosen and the following results have been obtained. 1. The ground coal is added to the slurry prior to the filters and the rotary dryer. 2. By adding 0.6% coal, an increase of about 15% in production rate has been obtained. 3. No significant changes of metallurgical properties have been observed (i.e. tumbler index, compressive strength, ferrous iron content, reducibility, Linder degradation and swelling). 4. No unexpected operation problems have been experienced. The pellet discharge temperature increases and is the limit for how much production can be increased by coal addition without making plant modifications.

Jan 1, 1971

By Pedro Pablo Vasquez Coronado, Victor Octavio Tenorio

"Productivity in openpit mines depends on the observation and adjustment of critical phases of operation. As one of the most expensive activities in openpit production, optimization of the load-haul-dump cycle becomes a critical aspect to address. Using simulation techniques and an ad hoc methodology for analyzing the key performance indicators (KPIs) involved in the production cycle, it is possible to compare actual performance and ideal operating conditions and develop an alert system when operating conditions are subpar with the expected production standards.Study objectivesThe purpose of this work is to implement a methodology for optimizing the haulage cycle by identifying and adjusting the factors that affect the cycle time performance. The methodology includes the implementation of an alert system emitting warning messages when one or several trucks are idle, or when the time of completing production tasks is falling outside a predefined value. This alert is compared with predefined KPIs and is used to determine corrective actions.The alert will:• Demonstrate the benefits of time analysis and how this affects the productivity results in the mining process.• Demonstrate the utility of KPIs in the extraction of ore and waste and how they help to identify equipment performance.• Develop software interfaces to visualize the alert system in order to increase awareness in the operations supervisor.• Make recommendations for future applications that can help improve the productive process of an openpit mine.Problem statementTransporting material in openpit mines may require the utilization of high capacity equipment, which also represents an elevated cost per hour. A supervisory system that controls the adequate distribution of trucks and shovels by providing the operational status of each unit shall contribute to increase productivity while subsequently reducing operational costs. Nevertheless, there is an issue with certain dead times such as queue trucks for loading, trucks waiting to be loaded and other delays. This creates inefficiencies in fuel consumption and energy utilization.For the identification of delays, a contextbased system could be required in order to help optimize the haulage cycle time by controlling delays in loading, haulage and dumping. After applying this methodology, efforts were focused in correcting out-of-standard performance values."

Jan 1, 2015

By Wenjun Ju, Xiaodong Sun, Jianwei Zheng, Bingding Yi, Zhaorui Ma, Pengfei Jiang, Lingfu Zhu, Yangfa Zheng

The presence of hard roof poses a significant threat to the safety of underground coal mining. In this study, a mechanical model is established for underground stopes to analyze the overburden structure with the advancing of the mining face. It is indicated that the load-bearing arch structure (LBAS) is formed above the stope for roofs with regular hardness, whereas the reversed-basin bearing structure (RBBS) is formed for hard roofs. Compared with the LBAS, the RBBS can induce an additional pressure at the foot of the bearing structure, and this effect becomes less as the distance between the hard roof and stope increases. The ultra-deep borehole hydro-fracturing technique (UHT) is proposed to weaken the hard roof for pressure release, and the associated equipment and procedures are also presented. The UHT is based on horizontal drilling along the axial direction of the roadway in the roof, and then the receding segmented hydraulic fracturing technique is used to achieve the purpose of fracturing (weakening) of the surrounding rocks. Field tests are carried out in 3022 roadway of Daliangwan coal mine in Yulin to assess the developed technique, equipment, and fracturing procedures. To evaluate the fracturing effect, deep borehole stress-meters are installed at different depths of the fractured and un-fractured zones of the roadway, along with hydraulic support pressure sensors placed at the mining face. The results show that compared with the un-fractured zone, the pressure on the wall and pillar sides is lower than that in the fractured zone, and the associated weighting duration and weighting area ratio of the fractured are reduced by 53.23% and 33.59%, respectively. This indicates that the presented UHT can provide a new solution for the prevention and control of mining disasters induced by hard roof failures in underground coal mining.

Nov 2, 2020

By E. G. Kelly

This paper describes the performance of a modern compound trough profile spiral that is optimized for fine coal cleaning. Reduced performance (Tromp) curves are presented to compare these new spirals with older designs, as well as with other commonly used coal cleaning equipment. As an aid to equipment selection and circuit design, data are also presented to show how variables, such as flow rate, pulp density, and particle size affect efficiency and the separation specific gravity.

Jan 1, 1984

By Guy T. McBride

Mr. Chairman, Fellow Keynoters, Ladies, and Gentlemen: It is purposed to consider the theme of this meeting, "The 1970's - Pivotal Decade for the Mineral Industries," from the particular -- some would say peculiar -- point of view of one engaged in mineral engineering education, and this coign of vantage prompts the textbookish subtitle, "Problems and Solutions (?) in Undergraduate Mineral Engineering Education." Three interrelated problems, or problem areas, will be presented and discussed, and where solutions seem to be emerging or seem worthy to be suggested, they will be identified. The three problems are: 1. The goals, and therefore the course requirements, of the undergraduate curricula are in question, 2. The unit costs of undergraduate education appear excessive to those who bear the charges, and 3. The social ambience of the day affects for the worse the work attitudes and the career motivation of both prospective and in-course students. The Need. - Any discussion of these problems must bottom upon recognized national needs for minerals and a technologically sound minerals industry staffed by competent engineers, particularly at the exploration, development, and production levels, Fortunately, these needs have been recognized and to some extent quantified, and they are even now under further intensive study by some of the most competent members of our society and profession. The latter reference is, of course, to the current work of the National Commission on Materials Policy (U.S.A.) under the executive directorship of Dr. James Boyd. Predating this, and perhaps to some extent

Jan 1, 1972

By C. J. Weiss

"A commercially available Through-the-Earth (TTE) communications system was evaluated at an underground coal mine in eastern Kentucky. This field study was conducted as part of a larger multi-site evaluation of available TTE systems to determine their operational sensitivity. Field testing is being performed along with simulation techniques developed for geophysical surveys. The results of the field test will additionally be used to determine the applicability of these simulation techniques to TTE communications. The mine detailed in this paper was idled at the time of the study, which provided the nearest practical representation of a post-event mine shutdown. For this study, the three following communication modes were tested: surface-to-underground, underground-to-surface and surface-to-surface. Standard deployments of the TTE system using the manufacturer’s recommended procedures were able to achieve clear communications between underground and surface locations. Other arrangements of the units yielded intriguing results, some of which were predicted by computer simulations, others were unexpected. Future experimentation is planned to further evaluate the observed phenomena. INTRODUCTION The ability to establish effective communication between surface and underground personnel after a mine event is essential for both mine evacuation and mine rescue efforts. Current communication technology is reliant on physical infrastructure, such as antennas, cables, and repeaters, located throughout the mine. Such systems are easily disabled during a mine event because of their vulnerability to physical damage. A true emergency communications system would have the ability to function regardless of a mine’s physical state. Through-the-Earth (TTE) wireless communications technology has the potential to provide such a tool. Wireless TTE communications are exceptionally challenging because electromagnetic (EM), or radio, signals are subject to drastic attenuation as they travel through solid strata. In addition to attenuation, EM wave propagation is directly affected by the physical and petrographic characteristics, mineral compositions, metamorphic properties, and the degree of water infiltrations in the strata [1-5]. These strata characteristics are unique to each mine thus making the design of an effective, universally deployable, and reliable TTE communications system very difficult. At present, TTE technology is in the preliminary stages of practical deployment with only a few permissible TTE systems commercially available."

Jan 1, 2015

By Chee Theng

"Mineral processors know you can put in the best technology in the world but it won’t work optimally without the support of the operators. Conversely, you may have complete operator support but won’t get top results without the right technology. When the two come together, the returns can be phenomenal.The first day of talks at the 68th Annual Colorado MPD Conference, held April 26-28 at The Broadmoor in Colorado Springs, covered the ground on these industry wisdoms.Coming together as a team“Think of the people, not just the lab and the numbers. That makes all the difference,” said Dee Kippers, of FMI Henderson Mine, in her talk on “Process optimization during a market downturn (A Moly MacGyver story).” Kippers told an entertaining story of the journey she and her team took in tackling the issue of an annual spike in iron content in the product at Freeport- McMoRan’s Henderson primary molybdenum mine near Empire, CO.As the metallurgists tried one thing after another — cranking up the iron depressant, adjusting pH with sodium hydroxide and hydrated lime, modifying reagent levels — Kippers found that when she shared her results with the operators, communicated with them on what she was doing and got their input, they were more willing to work with her, and more understanding and supportive of her efforts.The results make the case for getting people on board and coming together as a team. The cost savings from their optimization efforts, with little capital investment, have been “enough to cover the annual salaries of our metallurgy department and then some,” Kippers said.Considering the environmentDavid Lemieux, of Dundee Sustainable Technologies (DST), talked next on “Cyanidefree process for gold extraction,” presenting the results obtained from a demonstration campaign of the company’s novel chlorination process for gold extraction and associated arsenic stabilization process. Developed at an investment cost of C$35 million, they are ready for commercialization, having been demonstrated on the laboratory, pilot and demonstration scales.The DST process is differentiated from the Plattner chlorination process, which was in use from 1851 to 1916, by moderate process conditions of atmospheric pressure and ambient temperature — the result of using sodium hypochlorite solution, or bleach, instead of direct injection of chlorine gas — and new, cheaper materials of construction, such as polymers, plastics, fiberreinforced plastics and Teflon, resulting in lower capital and operating expenditures."

Jan 7, 2018

By J. B. Malcolm

The discovery of tungsten-bearing quartz outcroppings in Vance County, N. C., by the Hamme brothers in 1942, made international news in the mining industry and was, in fact, one of the major ore discoveries made in the U.S. during the last 25 years. Operations began at the Hamme mine in 1942, but after 16 years of successful operation, the mine was closed down in 1958 under adverse market conditions. By that time, it had produced nearly 20 million lbs of metallic tungsten. Because of the square-set timber mining method then in use, mine operating expenses were high, actually representing 78% of the total operating expenses at the property. In timber work alone, 160 men were employed. Approximately 500,000 bd ft of timber were placed monthly at a direct supply cost of $1.00 per ton of ore mined. Late in 1959, following a slightly improved position in the tungsten market, company management decided that, by changing the mining method, the operation could be economically feasible. The major premise in this decision was that a reduction of from 25 to 30% of the mining costs could be achieved by the conversion of the mining method from square-sets to horizontal cut and fill. Reopening of the mine began in February 1960, Full production has now been reached and overall mine productivity has been doubled.

Jan 1, 1962

By S. J. Schatzel, V. Gangrade

A ventilation research study was conducted by the National Institute for Occupational Safety and Health and a cooperating trona mine in the Green River basin of Wyoming, USA. The mine operation uses the longwall mining method in trona bed 17, a commonly mined unit in the region. The longwall face length is 228 m (750 ft), and caving on the face occurred up to the back of the longwall shields. The mine is ventilated using a main blowing fan and a bleeder shaft. For this study, sulfur hexafluoride (SF6) tracer gas was released in two separate monitoring experiments. For the first experiment, tracer gas was released on the face, this test focused on airflow along the longwall face of the active panel. Face test showed the airflow patterns to be more complex than just head-to-tail flow in the main ventilation air stream on the active panel. For the second experiment, tracer gas was released 2 crosscuts inby the face on the headgate side, this test focused on gas transport in the mined-out portion of the same active panel. Gob test showed a pathway of movement through the front of the active panel gob that moved outby from the tailgate corner. The primary pathway of tracer gas movement in the active panel gob was towards the headgate and tailgate bleeders and out of a bleeder shaft. The rate of movement towards the back of the gob was measured to be 0.19 m/s (37 fpm).

By J. Raatikainen, I. Auranen

"INTRODUCTION Sorting technology has advanced rapidly recently. Of the two possibilities particle sorting has advanced especially in introducing new sensors and the use of multiple sensors. The analyzing and computing lead times have also shortened. This has made it a viable technology option for many applications but not for the most important sorting task at a mine; the run-of mine ore. Bulk sorting, however, has advanced in smaller steps, even if the technology has the capability to tackle the run-of-mine ore and offers a high potential to bring mines substantial economic benefits. The sensors, which are useful are restricted by the difficult operating conditions or by the ore characteristics. One of the important features of run-of-mine sorting technology is the major material handling infrastructure required. The capital expenditure can be substantial requiring good understanding of the sortability curve (grade-recovery curve) behavior of the ore. This paper discusses one industrial case, where substantial amount of data measured from the ore feed belt has been obtained. This data was then analyzed for the grade recovery curves obtainable from that ore with sorting. EXPERIMENTAL The XRF measurement used was the FCA device from IMA Engineering (Fig.1). It is a specially built version of XRF designed to operate with coarse material. The measurement was situated at the main belt conveyor taking ore from the primary crusher to the stockpile. The crushed ore was about 80% -300 mm at a capacity of 1100-1200 tph (Fig.2). Measurement times were varied from 30 seconds to a minute. Measurements were obtained over several months.As the XRF is a surface distribution measuring technique, the measurement was first tested upon accuracy and reproducibility against plant daily wet chemical assays and against on-line Courier feed analysis. As there is a varying delay in the ore stockpile, the delay time was used as a variant in the validation. Different measurement times were tested for accuracy. A one minute measurement time gave a total measurement relative standard error, which was both for Cu and Ni below 3%. The results showed also very robust correlations; for Cu, the correlation coefficient was R > 0,94 for one minute measurements over three months and R > 0,86 for Ni respectively. Fig 3. Shows a measurement period of two hours showing substantial feed grade variations (given as relative value; 1.0 represents the mean value during the measurement month)."

Jan 1, 2018

By George Vranesh

Synfuels development in the upper Colorado River basin and the population growth attendant with such development demand sizeable quantities of water. Unfortunately, the water supply in the basin is limited and such limitation may impose a significant constraint on the development of the West's abundant energy resources. Although the water for the synfuels development will be governed by the law of prior appropriation adopted in the upper basin states, the authors point out that an apparently senior water right .my not deliver a firm supply of water. The federal and Indian Reserved Water Rights Doctrine, the Colorado River Compacts the Doctrine of Equitable Apportionment, and the federal and state environmental laws can all severely diminish the value of any given water right and the synfuels industry should take care to evaluate these factors in acquiring its water.

Jan 1, 1981

By Marc Carriere

Bright-orange couplings adorning piping systems are a common sight in just about every underground mine in North America. Grooved mechanical piping, the pipe-joining system that utilizes these couplings, is the preferred method for joining underground and plant piping systems in the mining industry, due to the ease and speed of installation and maintenance. However, the applications for such systems have traditionally excluded high-pressure systems. Most grooved mechanical couplings have a moderate working-pressure limitation, so high-pressure systems have required the use of alternative joining methods, typically heavy-duty flanges. However, the introduction of high-pressure couplings (up to 4,000 psi) has made the grooved joining method viable, and even preferable, for backfill, deep-mine chilled water and dewatering lines and other high-pressure piping applications. As engineers explore the use of high-pressure couplings, questions will undoubtedly arise about the joining method?s capabilities. This article will address the capabilities and specifications of high-pressure couplings, and compare flanged and grooved mechanical pipe joining in traditional as well as high-pressure underground mining applications.

Jan 1, 2011

By B. M. Eiter, J. Hrica, D. R. Willmer

"Mineworkers are routinely tasked with making critically important decisions about whether or not a hazard presents an imminent danger. Researchers from the U.S. National Institute for Occupational Safety and Health collected formative data to investigate mine safety professional perspectives on workplace examinations, which revealed a potential gap in how mineworkers are assessing risk. During interviews, participants revealed not having a systematic methodology for mineworkers to use to determine if a hazard is considered imminent danger. In this paper, we identify and describe three distinct categories of imminent danger complexity and discuss potential steps that could lead to improved identification of imminent danger situations. Finally, we identify potential practices to incorporate into risk management efforts, including feedback, communication and specialized training, to increase awareness of imminent danger situations. IntroductionIn recent years, the metal and nonmetal mining sector, as categorized by the U.S. Mine Safety and Health Administration (MSHA), experienced an increase in the number of fatalities occurring at mine sites. From 2013 to 2015, 69 mineworkers were fatally injured, twice the number of fatalities in each of the previous two years (MSHA, 2015a). As a way to address this increase, MSHA issued its P15- IV-01 program policy letter, suggesting that “miners would benefit from rigorous workplace examinations conducted by experienced and trained examiners” (MSHA, 2015b). The goal of these examinations is to find hazards in the field and mitigate them before they cause injury or death to mineworkers. While it is important to identify all hazards in the workplace, it is critically important to identify those hazards that are considered imminent danger because they require an immediate response to avoid a severe or even fatal injury."

Jan 9, 2018

By Fernando Jorge Dick

Artificial sulphides have been produced on the surfaces of heavy metal-oxide, minerals at elevated temperatures (1) and these sulphides gave consistently similar flotation characteristics as the respective natural sulphides. In the case of tin, the only natural tin sulphide known is herzembergite (SnS) which is found only in minor quantities, and its flotation behavior is not known. Balberyszki, Dorenfeld, and Carmi reported (2) tests with artificial tin oxide and pure cassiterite treated with hydrogen sulphide at temperatures above 750oc. They confirmed that the product could be floated in acid pulps. However, iron sulphides derived from pyrite, limonite, and hematite which are generally the major impurities in tin bearing ores could not be separated from tin sulphides under the conditions used by previous investigators. As a practical matter, if complex tin ores or complex low grade tin concentrates are to be treated by this process, it is necessary to be able to separate sulphidized cassiterite from other sulphidized minerals in the feed. The major metallic minerals, by weight, in complex tin ores are the iron minerals--pyrite, hematite, limonite, magnetite and pyrrhotite. These minerals become (or remain) sulphidized during the sulphidization process.

Jan 1, 1978

By Onuralp Yücel, Kağan Benzeşik, Ömür Can Odabaş, Selçuk Kan

Extraction and processing constitute an important area in the metallurgy of molybdenum. Molybdenum trioxide (MoO3) production is one of the most important stages in molybdenum production. In this study, the effects of different furnace types on MoO3 production were investigated by using molybdenum concentrate as a raw material obtained during the enrichment of copper ores. Preliminary experiments have been made using a chamber type furnace, and a transition to a pilot-scale has been carried out with rotary kiln experiments. The effects of a different time and atmospheric conditions on MoO3 roasting kinetics were investigated by experimental studies conducted in the temperature range of 500–650°C. It was determined that the optimum temperature and time for sulfur (S) removal was 625°C and 180 min in the studies carried out in the rotary kiln, and it was determined that 0.61%S content was reached with an average removal efficiency of 98%. The activation energy in these sets was calculated as 89.519 kJ/mol.

May 3, 2021

By Harry M. Conger

Thirty years ago, the U.S. gold mining industry was hanging on by its fingernails. Save for one great mine, the Homestake, most production was coming from copper smelters such as Kennecott and Magma. Even Homestake itself was under great pressure from rising costs and a fixed price for gold. The outlook was dim, to say the least. Today, as it has for most of the past decade, the American gold mining industry stands among the world leaders in production, and in the development of mining and mineral processing technology. What caused this dramatic change? Obviously, the freeing of the gold price was a major factor, as was the decline in South African production, but these events alone could not have created the U.S. strength we see today. It was technology, investment, and the determination of miners to build an entirely new industry that were the indispensable ingredients. The U.S. Bureau of Mines, with great foresight, had begun the research that led to heap leaching before the gold price began to rise, and Newmont had committed to build a small mill at Carlin, a move then considered quite risky. From that point, the U.S. gold mining industry was placed on lower-grade ores then being found in Nevada and elsewhere, but it was soon apparent that we would have to develop new technologies to deal with more refractory ores, carbonaceous as well as sulfide-bearing. This is now being done with considerable success. Despite its success, or perhaps because of it, the gold mining industry has come under pressure from various groups who characterize their activities as motivated by "public interest." The public interest they refer to properly include the health and safety workers and impacted communities, as well as protection of the environment, and with these concerns we miners have relatively little argument. In fact, we consider health, safety and the environment among our highest priorities, and not just because regulations may require us to do so. The argument, however, is not about the regulation of a viable mining industry, it is about a well-organized movement to attack and condemn mining in the media and to misrepresent its importance to the Nation and its willingness to accept responsible regulation. Once largely local or regional, the interest groups to which I refer are now quite large, national in scope, and even becoming international. This trend, taken together with finances raised from their dues and contributions, would make the interest groups formidable adversaries for mining, but their grip on the media enormously magnifies their influence. Unfortunately, it also makes possible the wide dissemination of incomplete, incorrect or slanted information. I am not here to "bash" the interest groups. On the whole, I believe that many of them have made positive contributions to society. As conservationists, however, I question their authority to make, or foster, decisions about which American industries and communities live and which die. To illustrate, I would like to present for your consideration the problem of cyanide, one of the issues over which the gold mining industry is most threatened. CYANIDE-POISON OR MIRACLE SOLVENT? Let me get this out of the way right up front: cyanide in most of its chemical forms is toxic. In some forms it is also listed as a carcinogen. These are adverse characteristics cyanide shares with a considerable number of industrial chemicals, including some that are widely used without the stringent regulations already in place for the mining uses of cyanide. In these uses, by the way, the risk to humans comes from direct ingestion of cyanide or cyanide-bearing solutions, or from the accidental acidification of solutions leading to release of hydrocyanic acid gas. That these risks are under control in mining can be seen from the fact that, in modern U.S. practice, there has never been a documented fatality attributed to cyanide! Because of its toxicity, cyanide cannot enter and be accumulated in the food chain. It can, however, be a threat to birds and animals that ingest cyanide-bearing solutions. Protection against this is, quite properly, a responsibility of individual mining operations, and considerable sums are spent each year to prevent or reduce bird and animal exposures. It should be evident, though, that many human activities, including highway traffic, windmills, use of pesticides and the like, result in bird and animal losses. Mining's use of cyanide, and the measures taken to protect birds and animals, should be considered in context. Cyanide must be kept out of surface streams and groundwater, and existing regulations mandate this. Any cyanide residues left in leach heaps, waste dumps and disused facilities must be eliminated, and we have proven technologies to do this now, just as we have means to detoxify tailings prior to disposal. The gold mining industry decries those rare instances when irresponsible operators fail to deal with contamination, and agrees that they should be held responsible. We do not agree, however, that the great majority of responsible companies should be punished, in advance, for accidents that have never happened. So much for the poison, what about the "miracle solvent?" Is that an overstatement? Well, consider the fact that gold has been called "noble" from earliest times, because it does not oxidize under atmospheric exposure, and that it appeared to the ancients to be utterly insoluble. Later generations of scientists did discover that it could be dissolved, but only by a combination of acids so potent that it became known as aqua Regia. Later still, it was found that chlorine would also dissolve gold, and attempts were made to base commercial processes on this, without a great deal of success. It remained

Jan 1, 1995

By Lawrence H. Roth

Past failures of coal refuse embankments have resulted in intensified efforts in inspections of coal refuse sites by the Mining. Enforcement, and Safety Administration (MESA). MESA inspections however, are mainly qualitative and are often time consuming, Therefore, in August 1975 CH2M HILL was awarded a contract to identify, develop, and test a rapid system for monitoring coal refuse embankments to aid in MESA inspections. The rapid monitoring system developed uses convergent and vertical photography from conventional fixed-wing aircraft. The system was tested on an active landslide and on two coal refuse facilities using both black and white and color infrared film. Field tests showed the system was capable of accurate measurement while providing qualitative data through photo interpretation. The accuracy of the system allows it to be used to monitor coal refuse embankments, tailings dams, major earth dams, and natural slopes. Based on CH2M HILL results cost for monitoring by rapid system was approximately 25 percent of cost by conventional ground survey.

Jan 1, 1980