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By AIME AIME

C. H. BENEDICT, chief metallurgist of the Calumet and Hecla Consolidated Copper Co., has pioneered for nearly half a century. Noted for his ammonia leaching process, lie has Iong been responsible for all Calumet and Hecla mill, concentrator, and reclaination plant flowsheets. His influence has spread far beyond his own organization. lie is dean of Lake Superior metallurgists and has contributed greatly toward raising his specialty-the country over-to an honored profession; not merely an honored profession but a profitable one for industry and the public. The leaching process which he developed in 1912 has, since 1915, produced for Calumet and Hecla 250,000 tons of copper from waste tailings at a cost per pound, in 1929, below five cents. It has yielded profits of $35,000,000. In the war just ended, this process proved the only one adaptable to the recovery of copper from gilding-metal¬clad steel strip, and Calumet and Hecla treated more than 50,000 tons of such scrap for the Government.

Jan 1, 1945

By Tan Xiang-Kun, Liu Ming-dong, Yao Dun-Pu

Since the 1980s, heap leaching of gold and silver ores has been developing rapidly and experienced widespread use in China because of its lower capital and operating costs, less time consumed in construction and specific applicability to small-to-medium scale mining operations and low grade ores. Ores treated include ordinary oxidized ores, refractory sulfide ores and even those containing deleterious elements (such as arsenic or antimony) and/or carbonaceous substances. In addition to chemical leaching agents, some micro-organisms (e.g. T-ferrooxidians and T-thiooxixians) and their biochemistry mechanism have been equally emphasized. To overcome the adverse effect caused by excessive content of fines and slimes, research and pilot experiments of agglomeration-heap leaching are currently underway at two gold mines in South China and their encouraging preliminary achievements will be briefly described as illustrations in this paper. It could be expected that heap leaching of gold and silver ores holds promise and will play an increasingly important role in China's gold industry.

Jan 1, 1998

By Michael D. McGill

The effect of fragmentation size distribution as it relates to front end loader productivity was evaluated by comparing loader cycle times to fragmentation size of the shot rock. At Gold Mine in Southern Utah, a gold deposit containing both limestone and sandstone formations were blasted in the same shot.

Jan 1, 1994

By Douglas R. Cook

Our present and future needs for base and previous metals are not satisfied by the present rate of new viable discoveries. This deficiency can be met by increasing the number of competent exploration organizations and by doing a more effective job of prospecting. My principal purpose is to show that new discoveries can be increased by improving the use of exploration techniques in a concept-oriented exploration program. Exploration techniques are defined and classified. The effectiveness of many exploration groups can be improved by better definition of objectives and thorough planning of the exploration program. The role of objectives, planning, and the use of techniques are discussed within the scope of the exploration framework. Common pitfalls in the use of exploration data are identified such as: inconsistency of geologic measurements, negative use of data, indiscriminate use of geo-surveys, collection of irrelevant information, and the unrealistic desire for exploration panaceas. Suggestions for improving the use of techniques include the use of multiple-working hypotheses, improvements in the quality of exploration data, use of geology in the selection, planning and interpretation of geochemical and geophysical surveys, and the recognition of variables and limitations affecting the interpretation of exploration data. The critical role of geologic mapping by Federal and State agencies is mentioned for satisfying the continual exploration demand for better geologic maps and filling many gaps that currently exist. The importance of imaginative and qualified exploration personnel is discussed as well as the maximum utilization of their exploration creativity. The problem of integrating field studies, research and training at universities and research institutions is identified. The need for high-quality research in economic geology is emphasized especially the importance of reducing the steadily increasing gap between basic and applied research.

Jan 1, 1968

By D. F. Coates

El presente texto describe los procedimientos que deben seguirse en la selección de pernos para sujeción de techos, proyecto de patrones y control de varios aspectos de la reacción del terreno, de acuerdo al Departamento de Minas del Gobierno de Canadá. El objeto del empernado es proporcionar el soporte del techo para el período de tiempo limitado -que es corriente en la construcción antes de que sean colocados los forros permanentes en las labores de extracción y galerías. Consecuentemente, esto no cubre el uso de los pernos en lugares tales como puntos de arrastre en los pozos de las minas y en las instalaciones permanentes.

Sep 1, 1972

By Eileen Ashworth

Computer-assisted instruct ion is now being used in areas as diversified as training handicapped children to preflight simulation for airline pilots. This paper reports on two courses that have been developed at SDSM&T on the PLATO system for miner safety training. Advantages of computer-assisted instruct ion for this type of training is discussed. (Figures show examples of actual use.) A discussion will be given on other applications such as maintenance troubleshooting, training of engineers and managers at remote sites and training of local people for working in the mine.

Jan 1, 1983

By W. B. Agocs

IN August 1954 a low altitude test geophysical survey was made in the Green Pond area of Morris County, New Jersey, with a Gulf Research and Development Co. Model II total magnetic field variation magnetometer mounted in a Sikorsky S-55 helicopter. The test was made in this area to compare the results of a high precision, very low altitude magnetometer survey with an existing ground magnetic survey in this area having known magnetite concentrations, so that the method could be used in areas of difficult access for the detailing of airborne magnetometer anomalies of interest in place of ground surveys. The load capacity of the Sikorsky S-55 permitted installation of a recording scintillation counter so that a radioactivity survey would be made simultaneously with the magnetometer survey. The area surveyed is located at approximately 41°00'N and 74o28'W, just south and east of the town of Green Pond, N. J. The outstanding topographic feature of the region is Copperas Mountain, a well defined ridge, maximum elevation 1222 ft, which runs the entire length of the survey. The lowest point in the survey, 810 ft, is in the extreme eastern corner. Topography of the area is shown in Fig. 1. The three major rock units outcropping in the area are all metamorphic: the Pochuck gneiss, which has been divided into two metamorphic facies; the Byram gneiss; and the Green Pond conglomerate. The relative ages of the Pochuck and Byram formations, both pre-Cambrian, are in doubt, but it is believed that the Pochuck is the older of the two.' The Green Pond conglomerate is Silurian.' Distribution of the outcrops and mine locations is shown in Fig. 1. Two facies of the Pochuck gneiss can be distinguished locally—the Copperas Mountain and Kitchell members. The Copperas Mountain member is a hornblende gneiss, and all the mines and prospects in the area are in this unit. The Kitchell is a quartz-plagioclase feldspar gneiss. The Byram gneiss is a relatively nonresistant valley formation which is high in the potash feldspar. The Green Pond conglomerate is a well indurated quartzite-conglomerate which forms the Copperas Mountain and the Green Pond Mountain's ridge to the north. It overlies the gneisses with a strong angular discordance that may be a fault. The geologic structure of the Green Pond area is relatively uncomplicated. The foliation planes of the gneisses dip steeply to the southeast, and the Green Pond conglomerate dips steeply to the northwest. Additional faulting in the area is indicated at the contact between the Kitchell member of the Pochuck and the Byram along the base of the topographic spur extending to the southeast from Copperas Mountain. The magnetite mines of Pardee, Winter, Davenport, Green Pond, Copperas, and the Bancroft shaft are described by Bayleyl and Stampe2.' The ore is in the Copperas Mountain member of the Pochuck gneiss. The magnetite veins are 10 to 50 ft wide and up to 300 ft long, dipping to the southeast at angles ranging from 40" to 75". The locations of these mines are shown in Fig. 1. Dip Needle Survey: The dip needle survey shown in Fig. 2 was taken from a U. S. Bureau of Mines Report of Investigations." The figure numbers below the local, individual map area outlines refer to the figures in the aforementioned reports which were not contoured. The area of the dip needle survey was confined almost exclusively to the outcrops of the Pochuck gneiss. The separation between survey profiles was 100 ft and the distance between stations on the profiles was 25 ft in highly anomalous zones to 100 ft in magnetically flat areas. A total of 16 1/2 miles of traverse was surveyed over an area of approximately 1/2 sq mile with 2050 stations. The magnitude of the magnetic anomalies is difficult to determine due to the lack of information concerning the type of dip needle used and the procedure followed in making the dip needle survey. This latter would include the method of "zeroing" the dip needle and the procedure of reading at the stations, whether on the swing or statically. Calibrations made of the Gurley dip needle, Lake Superior type, show a static sensitivity of 385 gamma per degree in the range from —25" to +35o, corresponding to a variation in the total field of —9600 gamma to +13500 gamma in a total field of 57000 gamma, inclination 72". The sensitivity increases to 16 gamma per degree from a deflection of 60" to 76", and from 76" to 172" the sensitivity decreases continuously to a low of 260 gamma per degree. From the above it may be seen that it is difficult to assign an arbitrary sensitivity for the dip needle used on this survey. However, an estimated value of 100 gamma per degree may be assigned. On this basis, the majority of the magnetic anomalies, whose deviation is +20°, would be 2000 gamma. Locally, west and northwest of the Pardee mine the magnetic anomaly is +50°, or 5000 gamma; in the Green Pond mine area deviations of +75" are observed that would correspond to anomalies of 7500 gamma. The areal extent and width of the dip needle magnetic anomalies is comparable to profile and station spacing. Hence it is concluded that part of the detail may be due to control, and the probable cause of the magnetic anomalies is at or near surface exposures of magnetite concentrations in the form of veinlets and disseminations whose locations correspond to the local magnetic anomalies. On the basis of the magnetics, none of the magnetite concentra-

Jan 1, 1956

By Paul Billingsley

THE development of the North Lily ground, which lies in the East Tintic district, Utah,. about half a mile northwest of the famous Tintic Standard mine, was undertaken by the International Smelting Co. on purely geological reasoning. The geologic theory on which this work was based resulted from several years' intensive study of the East Tintic district by the geological department of the International Smelt-ing Co., who were, during this period, indebted to many for valuable suggestions that were adopted and became part, of the gradually maturing concept. For example, E. J. Raddatz, president of the Tintic Standard Mining Co., first called attention to the significance of rhyolite alteration; J. W. Wade, assistant manager, contributed greatly to our knowledge of the great Tintic Standard orebodies; and so on all along. the line. In short, the ultimate theory embodies the aggregate experience and thought of all those most familiar with the area in question. The problem in brief was this: is the Tintic Standard deposit an isolated occurrence of ore, or are other ore deposits to be found in the vicinity? If the latter is the case, where can these others be looked for? The difficulty of the problem lay in the fact that most of the area is covered by rhyolite; beneath which lies the limestone in which the orebodies occur; so that the available evidence as to the structure of the formations, and, their mineralization; is of the slightest. The sav-ing features of the case, by means of which it proved possible to solve the problem, are three in number first, the rhyolite is pre-mineral and hence has been exposed to alteration by the mineralizing agencies; second, certain persistent dikes and fissures are con-tinuous through the rhyolite into the limestone below; and third, the extensive underground workings of the Tintic Standard gave a good basis for study of the sub-rhyolite structure and the occurrence of ore. The rhyolite overlies the Tintic Standard orebodies, and over them shows a large patch of brownish altera-tion. This patch proves to be due to chloritization and sericitization, which has spread out from certain zones of dikes, pebble-dikes and fissures. The dikes are com-posed of a light fine-grained rock which has been altered to an aggregate of quartz, alunite, and magnetite. They can be traced southwest to a common center in Big Hill, the entire mass of which is composed of the same material. The pebble-dikes, which consist of a mass of rounded pebbles, mainly quartzite, in a matrix ranging from the same quartz-alunite-magnetite rock as above to almost pure vein quartz, are closely asso-ciated with these light dikes, but in general extend farther northeast. They thus represent a specialized phase of the intrusive action of which Big Hill is the center. The brown chloritized rhyolite, then, is an alteration product due, in all. probability, to emana-tions closely associated with this phase. Since it coin-cides geographically with the Tintic Standard area of highly altered limestone, with its many great ore-bodies, it has been concluded, that it is the expression in the rhyolite of activities which have also altered and mineralized' the underlying limestone.

Jan 4, 1927

The development of information concerning mesothelioma in South Africa started with the 1959 finding of Dr. J. Christopher Wagner of cases of mesothelioma in persons living in the vicinity or working in crocidolite mines in Cape Province. After more than 40 years, the data from South Africa now provide important insights into the differences in mesothelioma risk associated with different asbestos fiber-types. Three case series reports and one analytical report were reviewed in this session. In total, information on 504 proven cases was presented. There were 28% of cases arising from occupational exposure in mining, 35% from non-mining occupations, 23% from environmental exposures; 14% where no exposure was established and 9% where the exposure was unknown. Among the 129 cases for which occupational exposure and asbestos fiber-type were established, 115 cases were associated with occupational exposure to Cape crocidolite; 1 case associated with occupational exposure to Transvaal crocidolite and 9 cases with occupational exposure to amosite (grunerite asbestos) and 4 cases with occupational exposure to mixed fiber-types. There were no cases associated with chrysotile asbestos. There were 33 cases of environmental mesothelioma linked to Cape crocidolite exposure and 2 to exposure to amosite and crocidolite but none to Transvaal amosite alone or to chrysotile. The evidence shows that amosite is capable of causing mesothelioma but that the major risk in South Africa is associated with Cape crocidolite.

Jan 1, 2008

By J. C. Haptonstall

The Bismark Mine is located in northern Chihuahua, Mexico, 150 km (95 miles) southwest of Ciudad Juarez (Fig.1). The ore deposit was discovered in 1979 and was placed in production in 1992. The production rate is about 2.4 kt/d (2650 stpd) from an ore reserve of 8.5 Mt (9.3 million st). Grades currently average about 8% zinc, 0.5% lead, 0.2% copper and 50 g/t (1.46 oz/st) silver. Substantial inflows of water into the underground mine complicate the operation. Complex metallurgy poses another challenge for the operators. Bismark is a joint venture with 90% participation by Minas Penoles, SA de CR of Mexico City and 10% participation by Promociones Industriales Banamex, S A de C V (PIB S A) of Mexico City. Anew company, Minera Bismark, SA de CV was formed to operate the property. Cyprus Minerals was a 40% participant in the joint venture but, in early 1993, sold its share to Minas Penoles. The Bismark Mine is one of the largest new underground mining projects built in Mexico during the last 10 years. It is the country's fifth largest underground metal mine and provides about 1 % of the world's zinc supply at about 50 t/a (55,000 stpy). Bismark is a trackless operation with overall productivities of 7.6 t/manshift (8.4 st/manshift). The 2.4-kt/d (2650-stpd) concentrator started up in March 1992.

Jan 1, 1994

By Stanley J. LeFond, Langtry E. Lynd

Elemental titanium has become famous as a space age metal, because of its high strength/ weight ratio and resistance to corrosion. However, the major use is in the form of titanium dioxide pigment, which because of its whiteness, high refractive index, and resulting light-scattering ability, is unequaled for whitening paints, paper, rubber, plastics, and other materials. A relatively minor use is in welding rod coatings, in the form of the mineral rutile. United States consumption of titanium dioxide in concentrates for these applications in 1982 was as follows: pigments, 630,000 st; titanium metal, 31,000 st; and welding rod coatings, 5,000 st. The only commercially important titanium ore minerals at the present time are ilmenite and its alteration products, and rutile. Titanium was discovered by Gregor in 1790, as a white oxide which he recovered from menaccanite, a variety of ilmenite occurring as a black sand near Falmouth, Cornwall. Barksdale (1966) stated that the fundamental chemical reactions on which the present day titanium industry is based were known before 1800, although it was not until 1918 that these pigments were available commercially on the American market. Pings (1972) outlined the early history of the titanium industry in the United States, referring to the work of Guise (1964) and others: Mining of titanium minerals in the United States began sometime between 1880 and 1900, in Chester County, Pennsylvania. Small quantities of rutile were also produced during that time in North Carolina and Georgia. In 1901 rutile was mined from a deposit near Roseland, VA, and was used in making titanium chemicals and for coloring ceramics. Ilmenite in the deposit was produced as a separate item in 1913, and rutile and ilmenite were obtained from this deposit through 1921. The mining of titanium bearing beach sands began in 1916 near Mineral City and Pablo Beach, FL, for the purpose of making titanium tetrachloride to be used in tracer bullets, flares, and smokescreens. The titanium pigment industry was founded in 1918. By 1928 a large part of the domestic production of rutile, ilmenite, and zircon came from Florida. However production ceased in 1929 in Florida with the mining of newly discovered deposits in Virginia which were mined until 1968. The discovery of new deposits in Florida, and the development of better mining and concentrating methods for low-grade sands, led to a return of activities in this area. The large deposits near Tahawus, NY. were brought into production in 1942 by National Lead Co. (now NL Industries, Inc.), and by 1949 this company was the leading producer of ilmenite in the world. In 1948 the extensive deposits of ilmenite and ilmenite-bearing iron ores were discovered in eastern Quebec. The large Trail Ridge sand deposit in Florida was discovered by E. I. du Pont de Nemours & Co., Inc. geologists in cooperation with the US

Jan 1, 1983

By Stanley J. LeFond, Langtry E. Lynd

Elemental titanium has become famous as a space age metal, because of its high strength/ weight ratio and resistance to corrosion. However, the major use is in the form of titanium dioxide pigment, which because of its whiteness, high refractive index, and resulting light-scattering ability, is unequaled for whitening paints, paper, rubber, plastics, and other materials. A relatively minor use is in welding rod coatings, in the form of the mineral, rutile. United States consumption of titanium dioxide for these applications in 1973 was as follows: pigments, 891,000 st; titanium metal, 40,000 st (=24,000 st metal) ; and welding rod coatings, 10,000 st. The only commercially important titanium ore minerals at the present time are ilmenite, and its alteration products, and rutile. Titanium was discovered by Gregor in 1790, as a white oxide which he recovered from menaccanite, a variety of ilmenite occurring as a black sand near Falmouth, Cornwall. Barksdale (1966) states that the fundamental chemical reactions on which the present day titanium industry is based were known before 1800, although it was not until 1918 that these pigments were available commercially on the American market. Pings (1972) outlines the early history of the titanium industry in the United States, referring to the work of Guise (1964) and others: "Mining of titanium minerals in the United States began sometime between 1880 and 1900, in Chester County, Pennsylvania. Small quantities of rutile were also produced during the time in North Carolina and Georgia. In 1901 rutile was mined from a deposit near Roseland, Va., and was used in making titanium chemicals and for coloring ceramics. Ilmenite in the deposit was produced as a separate item in 1913, and rutile and ilmenite were obtained from this deposit through 1921. The mining of titanium bearing beach sands began in 1916 near Mineral City and Pablo Beach, Fla., for the purpose of making titanium tetrachloride to be used in tracer bullets, flares, and smokescreens. The titanium pigment industry was founded in 1918. By 1928 a large part of the domestic production of rutile, ilmenite, and zircon came from Florida. However production ceased in 1929 in Florida with the mining of newly discovered deposits in Virginia which were mined until 1968. The discovery of new deposits in Florida, and the development of better mining and concentrating methods for lowgrade sands, led to a return of activities in this area. The large deposits near Tahawus, N.Y., were brought into production in 1942 by National Lead Co. (now N L Industries Inc.), and by 1949 this company was the lead¬ing producer of ilmenite in the world. In 1948 the extensive deposits of ilmenite and ilmenite-bearing iron ores were discovered in eastern Quebec." The beginning of the modern titanium metal industry was in 1948, when E. I. du Pont de Nemours & Co. produced the first metal. U.S. Bureau of Mines reports, which gave details of the Kroll process, together with the attractive properties of the metal for

Jan 1, 1975

By L B. Zhou, S Li, B L. Wang, S B. Li, Q Wang

The rapid development in ChinaÆs metal mine resources has caused a series of mine environment problems such as serious ecological damage and environment pollution, and secondary geological disasters. The paper has reviewed ChinaÆs metal mine development, including current status and environmental situation, analysed existing problems in mine development and environmental management, and proposed corresponding countermeasures and suggestions.CITATION:Wang, B L, Li, S B, Li, S, Zhou, L B and Wang, Q, 2012. Current situations, problems, countermeasures and suggestions for ChinaÆs metal mine development, in Proceedings Life-of-Mine 2012 , pp 353-356 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By T Baumgartl, R Akesseh, M Edraki, B Usher, M Shaygan

With the continuing demand for industrialisation and urbanisation, the rate of mining and processing lower grade ores will also increase, producing large quantities of waste. As extreme weather events associated with global climatic changes are to be expected, the risk from mine tailings management will also increase (Edraki et al., 2014). In sulfide rich tailings, weathering within the critical zone controls the fate and distribution of the contaminants such as copper, zinc, and lead in the environment (Hayes et al., 2014). Tailings evolve geochemically and physically with time as they age under the influence of complex interacting factors. Understanding of the complex interactions between these controlling factors is important for predicting and mitigating the potential risks associated with sulfide tailings such as generation of acid mine drainage (Lindsay et al., 2015). Wetting and drying initiates weathering processes, influencing the hydrological, geochemical and geomechanical properties of the tailings. In semi-arid climates where evaporation exceeds precipitation, salts may precipitate within the pore system as well as on the tailings surface. These salts become the temporal sink of heavy metals until the next episodic rainfall (Nordstrom, 2011, Grover et al., 2016). Therefore, using kinetic and static test to describe the trajectory of these material evolutions without considering the complex interactions could potentially lead to erroneous prediction. In order to understand these relations, the effect of drying and wetting cycles on the hydrological, geochemical and geomechanical properties of ageing tailings was studied to draw conclusions for advanced tailings site rehabilitation and mine closureCITATION:Akesseh, R, Shaygan, M, Usher, B, Edraki, M and Baumgartl, T, 2018. Wetting and drying cycles as a means to determine the effect and consequences of tailings ageing, in Proceedings Life-of-Mine 2018, pp 24–27 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By L. H. Duschak

"This paper is based on the results of work conducted of the bureau's experiment station at Berkeley, Calif., in connection with the investigation of properties and methods of utilizing Western magnesite. The experiments described herein were made under the supervision of the writer, by W. C. Riddell and E. H. Delius, of the station's staff.In calcining magnesite for the production of magnesium oxide to be used in the preparation of oxychloride cement, the calcium carbonate present in the original rock may remain unchanged or appear in the finished product, either as CaO, or in combination with SiO2, A12O3, etc. As there is reason to believe that free CaO may have an effect on the behavior of caustic magnesia in the cement reaction, it is desirable to have a method for the determination of the relatively small amounts of free CO in the presence of a large quantity of MgO.The extraction of the free CaO with water free from CO2 at once suggests itself as a possible method. The solubilities of Ca(OH2)2 and Mg(OH)2. are given by Seidell in his book an ""Solubility of Inorganic and Organic Compounds."" (2nd Edition, 1919) as follows:"

Jun 1, 1920

By AIME AIME

THE second meeting of 'the Open-Hearth Committee, 'sub-division of the Iron and Steel Committee of this Institute, was held at the Hotel Cleveland, Cleveland, Ohio; on Oct. 13-15. On Oct: 12, the Open-Hearth Superintendents visited the plants of the Youngstown Sheet and Tube Co. and. the Republic Iron and Steel Co. These men were courteously entertailled by the two companies and every facility for a thorough inspection was furnished. Luncheon was severed at the plant bf the Youngstown Sheet and Tube Co. The meeting was opened Tuesday morning with addresses by J. V. W. Reynders, President of the Institute, and Herbert M. Boylston, Chairman of the Ohio Section of the Institute. E. A. Whitworth, of the Gathmann Engineering Co., presided at the meeting and L. B. Lindeinuth was secretary.

Jan 1, 1925

By Marvin V. Damm, Lloyd C. Venburg, Dan Sokol

Analytical and computer models are used to evaluate information obtained from existing data and investigation programs so mine water control systems can be designed and developed. These models allow the geohydrologist to predict the amount of groundwater inflow and the impact of dewatering and stream diversion on the hydrologic regime, and to determine the schedule and equipment needed for mine dewatering. This article describes uses of the model and the essential components necessary to construct an effective and practical one. Hydrologic models are constructed to determine the extent that mining activities will affect the ground water and surface water hydrologic regime. These models range from basic analytical, mathematical models to the more sophisticated finite difference and finite element groundwater models. Many factors determine the degree of sophistication, including the mining stage, the complexity of the hydrologic regime, the mining process, and regulatory requirements. Model Uses The geohydrologist and engineer construct models so the entire ground and surface water handling and supply system can be integrated and optimized. These models can provide the following data: • Information for water balance studies-the entire hydrologic regime for the area, including precipitation, transpiration, evaporation, infiltration, runoff, and the effect of geologic features. • Data on seepage rates during mining. • Information to design the depressurization and dewatering system, including water well spacing, location of sumping systems, need for grout curtains, and possible horizontal drain and underdrain locations. • Data needed to schedule dewatering and mining operations. • Prediction of initial and long-term impacts of mining and dewatering, including local and areal drawdowns, effects on existing wells, and modifications to the surface-subsurface hydrologic regime. Potentiometric surface maps and hydrographs can be prepared from these data. • Prediction of the effect of discharge from the water control system on the surface hydrology and data input to design systems for water discharge, storage, recharge, or reinjection. The results of a computer study that illustrates the effect of dewatering and reinjection into an aquifer to confine the cone of depression are shown on the accompanying figure. • Information to forecast potentiometric surface recovery after mining ceases. The accompanying figure shows the pumping and reinjection rates in a program that is adequate to dewater a mine and permit the recovery of potentiometric levels to approximate premining levels after mining ceases. • Documentation and design information for monitoring systems to be installed during all mining phases. • Water quality predictions and geochemical changes, including the possibility of brackish or saline water intrusion because of extensive dewatering or depressurization operations. • Documentation and data for acquiring permits from regulatory agencies. Model Input Program For any model to be effective, detailed hydrologic and geologic data must be gathered from a review of existing information and from an investigative program. These data should cover entire model limits. Data updating, revising, and refining should occur as new information is received from the investigation and monitoring programs, and from the mining operation as it progresses through the pre-mining, mining, post-mining, and reclamation

Jan 8, 1982

By Lane White

Refractory gold ores are those from which a significant percentage of the gold cannot be recovered by conventional cyanidation. Historically, roasting has been the primary method for rendering such ores amenable to gold extraction; however, roasting creates environmental problems that are not acceptable in many locations. During the 1980s, consistently strong gold prices drew increasing attention to refractory gold ores, and new processing schemes were commercialized, most prominently aqueous pressure oxidation and more recently bacterial oxidation. Since 1985, pressure oxidation has been incorporated into four plants processing refractory gold ores. A fifth plant is scheduled for start-up in early 1990, and three additional plants are scheduled for production before late 1992. A technical session on treatment of refractory ores was included in the program of `World Gold '89, a Gold Forum on Technology and Practices' held by SME and the AusIMM in Reno, NV, Nov. 5-8, 1989. This article summarizes material from five of the papers presented during the refractory gold session and published in the proceedings of `World Gold '89,' edited by Roshan Bhappu and Rod Harden. The complete proceedings are available from SME Publications Sales, P.O. Box 625002, Littleton, CO 80162-5002 $53.50 for members, $38.50 for student members, and $73.50 list price.

Jan 1, 1990

By W. E. Cobb

Mining companies, as developers of natural resources, are being forced to deal with the potential long-term liabilities of past, present, and future mining operations. As discussed in a previous paper (Cobb, et al., 1987), these liabilities can include solid waste disposal corrective action programs (state or federal actions), Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), (Superfund) (state or federal actions), or natural resource damage claims (typically filed by state agencies and provisions specified in CERCLA). These potential liabilities are very real, and should dramatically impact the way a company views its exploration and development programs, and operating mines.

Jan 1, 1988

By Robert H. Carpenter

Downstream dispersion curves for certain trace metals were obtained from two mineralized areas in the southeastern U. S. In Lincoln Co., Georgia, 7 sample sets were collected downstream from the Magruder mine, a polymetallic sulfide deposit (Zn-Cu-Pb-Ag-Au) in metavolcanic rocks. Five sample sets were collected along Joe Mill Creek in Grainger Go., Tennessee, downstream from a zone of zinc mineralization in carbonate rocks (Mississippi Valley-type). In both areas, analyses were made of Fe-Mn oxide coatings on lithic fragments and quartz pebbles, and the -80 mesh fraction of the stream sediment. A comparison of the dispersion curves reveals the following: 1.) the anomaly/background ratio is markedly higher in the Fe-Mn oxide coatings for zinc and copper; 2.) the anomaly/background ratlo is markedly higher in the -80 mesh fraction for lead which is not concentrated in the coatings; and, 3.) the Zn/Mn and Cu/Mn ratios in the coatings are useful in that they enhance downstream derectability of mineralization as well as provide for a simpler analytical procedure. There are several potential advantages of using coatings vs. the conventional -80 mesh fraction in stream sediment surveys. Because soluble metal is brought into the stream mainly in groundwater, deeper anomaly sources may be detectable from the oxide coatings than from clastic fractions of alluvium where much of the metal is derived from erosion of soils. Variability due to sampling may also be reduced, providing better discrimination of anomalies. In areas of glacial or alluvial cover, coating surveys may be particularly applicable.

Jan 1, 1975