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By P. Rosario

During the last few years high-tonnage plants have been designed with comminution circuits using semiautogenous grinding (SAG) mills, high pressure grinding rolls (HPGR), or both, followed by ball mills in different configurations. A strong interest in improved energy efficiency and reduction of carbon footprint, along with the recent launch of new high-capacity crushers and stirred grinding mills, has driven the industry to investigate the development of novel flowsheets. This paper presents work based on recent projects that include modeling and simulation of two innovative circuits recently considered for current projects. One circuit uses autogenous (AG) mills and parallel trains of crusher-HPGR and the other is a modified three-stage crushing circuit with the use of HPGRs and pebble mills. The paper indicates the potential savings in operating costs provided by the HPGR-pebble mill circuit when compared to a more conventional SAG-mill-based circuit.

Jan 1, 2010

By L. B. Gittinger

Mr, Chairman, members- and guests of the AIMS, I greatly appreciate this opportunity to speak before you. I hope this is just the beginning of a long and mutually beneficial relationship. This winter I decided to join the other 36 Freeporters who belong to the AIME; and, I applied for membership in the Society of Mining Engineers. To queries as to my interests in the Society, I had this answer: our principal challenge -- more so today, than at any time in my nearly 25 years in the industry -- is discovery and development of new sources of raw materials. I want to join you in meeting this challenge.

Jan 1, 1966

By B. F. Westfall

Throughout the 1960's and 1970's world trade grew rapidly, reaching a peak of USS1.8 trillion in 1980. Since then the world recession of the early 1980's shrunk trade to about US$1.6 trillion. The reduced cash flow to developing economies made it difficult to service their huge international debts, Nowadays lenders are reluctant to grant Third World countries additional credit. The shortage of export financing, plus trade barriers set up by developed countries, is further inhibiting international trade. Therefore, countries are turning to new and creative alternatives to financing imports of consumer as well as of investment goods. Non-cash transactions, including different forms of countertrade, are rapidly growing alternatives to traditional trade financing patterns. In 1983 about 30% of international trade, or close to US$600 bill ion, were presumably done by non-cash transactions, up from barely 2% in 1976. By year 2000, half the world trade is likely to be conducted on basis of barter. As of mid-1984 some 88 nations used countertrade regularly and Governments of at least 15 Latin American countries had arranged or mandated commercial countertrade.

Jan 1, 1986

By John F. Burst

For several generations now, the high alumina clayey sediments of Southeastern Alabama and Southwestern Georgia have supplied those regions with steady, mineral-based income although the impact of that income has been relatively minor until recently. Since World War II, mining activity has increased algebraically with over half of the total ore value in the Alabama area having been recovered since that time. The Georgia area production increases are even more dramatic. The trends are continuing and the next decade should see ore winning figures which will dwarf all previous production. It's time for the mining engineers to take note of this development as the mining methods, similar to the production, have developed rapidly and now offer challenges for the most competent professional. The development of mining techniques has followed a classic pattern. Beginning almost a hundred years or so ago, with the loading of weather-resistant surface boulders into mule-drawn wagons, mining methods have progressed to discovery of limited surface exposures in outcrop and eventually to stripping and development of non-obvious, subsurface deposits. Little by little, the overburden thickness of new pits has increased until, at present, pits with 100' -125' of overburden are being actively worked. Ground water problems in the Eufaula District are particularly challenging. At A. P. Green's J. W. Baker Pit, #l, in Barbour Co., Alabama, it is necessary to continually pump groundwater at the rate of about 400 gallons per minute from wells on the periphery of this large pit in order to keep the water table low enough to allow mining of the ore body.

Jan 1, 1972

By W. Clark Ashby

Productivity is a fascinating concept. Like motherhood or apple pie, we know it as a good thing. Just what it means is not so clear. To a coal miner we assume it means tons of coal hauled from the mine. To the company president it means profit after capital, labor, and other costs have also been reckoned. To the government economist it means output in a balance of payments. What does it mean to the biologist, and can reclamation really be productive? In this paper we discuss productivity from a biological viewpoint, give some yield data for various types of reclamation plantings, and discuss how our demand for or acceptance of differing kinds of productivity is tied up in bigger questions of land use, environmental stability, and resource allocation.

Jan 1, 1981

By Junnan Chen, Hongwei Zhang, Wei Wang, Feng Xie

Thiosulfate is a green gold leaching agent that shows great potential to replace the highly toxic cyanide. Ammonia is traditionally used as the copper ligand in thiosulfate solutions to reduce the reactivity of copper ions towards thiosulfate, but it is a toxic reagent. As a result, efforts to replace ammonia with another complexing agent have received increasing attention. In this study, a novel alternative to ammonia is proposed to explore the potential use of the copper-malic acid-thiosulfate system. Experimental parameters include temperature, initial pH, copper, malic acid, and thiosulfate concentration. The feasibility of the copper-malic acid-thiosulfate system was discussed using Eh–pH and species distribution diagrams. Themodynamics analysis indicates that the mechanism of gold leaching in copper-malic acid-thiosulfate solution is mainly catalyzed by the Cu2( Mal)2H-2 2−/Cu(S2O3)3 5− redox couple. The capability of gold leaching in this system for processing the refractory gold concentrate is comparable to that of cyanidation and the traditional copper-ammonia-thiosulfate leaching processes. Thiosulfate consumption is greatly reduced in the presence of malate due to its strong chelating effect on the copper ions. Moreover, the copper-malic acid-thiosulfate system demonstrates a significant enhancement in leaching kinetics, making it a viable option for processing refractory gold concentrates.

Aug 1, 2023

By X. Zhou

In this study, the cyclonic static microbubble flotation column (FCSMC) was investigated for fluorite beneficiation. The structure and principle of the specially designed column are described. Fluorite samples from the tungsten separation tailings of the Shizhuyuan Mine, Chenzhou, Hunan Province, P.R. China, were tested using a small-scale continuous flotation test unit, and concentrates with a fluorite grade higher than 98% were obtained. One rougher and three cleaner stages in the FCSMC achieved the same separation performance as one rougher and eight cleaners in conventional flotation cells. This greatly simplified the flotation circuit and reduced operating costs.

Jan 1, 2007

By B. Seegmiller, W. A. Hustrulid, O. Stephansson

Introduction The concept of in-the-wall haulage was formally introduced to the mining community in the early 1970s. The basic concept is simple. Rather than the traditional in-the-pit haulage/access ramp, single or twin ramps driven in the pit wall are used with crosscut connections on the working levels. The in-the-wall pit haulage system could be considered as part of the opening of a new mine, a way of completing to final depth an existing pit, or part of the transition from open-pit to underground mining with the ramp remaining as part of the access. This paper is intended to acquaint the reader, particularly mine planning engineers, with some of the possibilities presented by the concept. Nordstrom (1983) said, "In many countries, mining engineers are either open-pit or underground specialists and, hence, often don't consider the possibilities for combining the best aspects of each into a hybrid mining system." This is believed to be true. There are few "hybrid mines" employing, for example, open-pit methods with underground haulage systems. One reason is the variance with the experience of the mining company and the engineers involved. However, with today's low metal prices, innovative and unconventional thinking may be just what a property requires to remain in production. All the possible situations where an in-the-wall ramp might be considered cannot be presented here. Rather, a few examples will be discussed for illustration purposes. Potential savings in stripping costs A major cost in open-pit mining is associated with the removal of overburden and waste rock. Although much of this stripping cannot be avoided, the volume (V) associated with the presence of an in-pit haul road can be quite large, V 100 (pit depth) a (road width) 2 x road grade (%) As an example, consider a vertical ore body 400 m (1312 ft) long, 60 m (197 ft) thick, extending to a depth of 160 m (525 ft). Cross sections are shown in Fig. 1. Other data are: ore tonnage = 11 Mt (12 million st), ore density = 2.9 t/m3 (0.09 st per cu ft), waste rock density = 2.7 t/m3 (0.08 st per cu ft), road width = 20 m (66 ft), road gradient = 10%, and level interval = 10 m (33 ft). The evaluation has been made assuming that the pit slope (0) is constant around the pit except on the side with the haul road. On this side, the slope is decreased to allow for the road. Slope angles of 30° to 60° have been selected to indicate the dependence of stripping volume (V) on slope angle. The stripping at the ends have been calculated assuming representation by cones. The volume associated with the haul road is 2.6 Mm3 (92.8 million cu ft). A comparison of the strip volumes involved is shown in Table 1. As can be seen, the percent savings in strip volume varies from about 4% to 17% and depends greatly on the slope angle. It is perhaps more interesting to examine the savings in stripping costs that could then be used to cover the cost of the access ramp and the crosscuts for stripping costs of $3/m3 ($0.08 per cu ft). The cost with the road volume is 2.6 million x 3 = $7.8 million.

Jan 1, 1988

By Michael Cruickshank

All life on Earth relies on the ocean and yet the ocean is 95 percent unexplored, unknown and unseen by human eyes,? said Paula Keener, director of education programs for National Oceanic and Atmospheric Administration?s (NOAA) Office of Ocean Exploration and Research. ?To better understand, manage and protect the ocean and its resources, NOAA believes it is critical to use the best technology to explore, discover, inform, educate and motivate? (MTS, newsletter, January 2011). In the last few decades, our understanding of the global mineral resource base has been drastically changed by some surprising new developments. The potential for commercial minerals per unit area in the oceans and seabed appears to be similar to that of the terrestrial lands. Thus, almost three-fourths of the global mineral resources are in, or under, the sea and are virtually undeveloped. The area of the Pacific seabeds alone is greater than the total area of the global lands. Half of the global seabed minerals are now controlled by nation states within their Exclusive Economic Zones (EEZ). The other half is controlled by the United Nations (UN) through the International Seabed Authority (ISA) within the ?areas beyond national jurisdiction? known as The Area. Thus, the Law of the Sea, ratified in 1994, has resulted in the largest transfer of control of natural resources in the history of mankind. This paper was prepared by the Society for Mining, Metallurgy and Exploration (SME) Committee on the Offshore Technology Conference for the SME Board of Directors and other interested parties. As the premier professional society for the mining and mineral community in the United States, with a history dating back to the 19th century, SME?s mission is to encourage and support young men and women engineers in the minerals industry, provide the services they need, improve the image of the industry, strengthen the networking among global industry professionals and engage in proactive collaboration among industry, government, academia and nongovernmental organizations (NGOs). The accomplishment of this mission can be strongly advanced by highlighting what is probably now the most significant development in the history of the modern minerals industry - the exploration of the marine environment and the understanding of the potential for the development of the minerals therein.

Jan 1, 2011

By Jon “Ike” Isaacson, Frank Perrone, Eric Prantil

"Tunneling through an urban environment carries many inherent risks to the immediate local infrastructure and subsequently to the project stakeholders. On the CQ031 Contract of the East Side Access Project in Queens, New York, twin 22.5’ diameter Herrenknecht Slurry TBMs were mined within close proximity to many infrastructure assets, with cover of less than half a shield diameter at times. Multiple public bridges and critical railroad infrastructure including catenary poles and signal towers supporting the busiest rail interlocking in the United States required underpinning systems. The support program for these structures was refined over the course of the four tunnel drives. It is the intent of this paper to show how the interaction between the temporary structures, instrumentation monitoring plan, and risk assessment program melded to provide a system which the owner, contractor, and designer relied on as a tool to ensure the project success without impacting the public surroundings. PROJECT BACKGROUND The East Side Access (ESA) megaproject located in New York City, N.Y is a multi billion dollar program for the Metropolitan Transit Authority Capital Construction (MTACC) with the main goal of bringing the Long Island Railroad (LIRR) commuter rail to Grand Central Station located in the heart of Midtown Manhattan. When completed, the project will significantly reduce congestion both into and out of Penn Station, the current terminus of the LIRR. In order to accomplish this, multiple contracts of varying scope are required to operate simultaneously in both Queens, N.Y and Manhattan. In 2009, the CQ031 Queens Bored Tunnels Contract was awarded to the joint venture of Granite Construction Northeast, Traylor Bros. Inc., and Frontier Kemper (G.T.F). The main scope of this contract was to excavate four segmentally lined soft ground tunnels underneath the Sunnyside Rail Yard in Queens, New York. Additional scope of work included the construction of a tunnel approach structure, electrical substation, and multipurpose ventilation and egress facility."

Jan 1, 2016

By F. L. Pirkle, D. L. Pirkle, E. C. Pirkle, W. A. Pirkle

Heavy minerals have been mined from the sands of the United States’ Atlantic Coastal Plain since the early part of the twentieth century. Production of ilmenite from beach sands near Mineral City (Ponte Vedra), Florida, began in 1916. The first reported large-scale recovery of zircon in Florida was reported from this deposit in 1922 and of rutile in 1925. These operations ceased in 1929. Today the Ponte Vedra Country Club and Golf Course is situated in the center of the former mining site. In 1942 heavy-mineral operations were established on 202 hectares of land situated in Duval County, Florida. The location is about 16 kilometers east of the center of Jacksonville, Florida, in an area known as Arlington. This operation demonstrated that low-grade sand containing only 2 to 3 percent titanium minerals could be concentrated economically with the Humphreys spiral and that the oxides could be separated from the heavy silicates by electrostatic methods. Much of this area is now covered by a large mall and is a major retail- commercial center. Between 1958 and 1964 the Skinner tract, a deposit about 4 kilometers south of the above deposit, was mined. Today the area of this deposit is known as Deerwood, a gated country club community on the southside of Jacksonville. Further inland, E.I. du Pont de Nemours and Co. has been mining heavy minerals from a physiographic feature known as Trail Ridge since 1948, and a deposit near Green Cove Springs, Florida has been in production since 1972. Since the start of heavy-mineral mining in the southeastern United States, nine heavy-mineral ore bodies either have been or are being exploited in Florida and Georgia. Other deposits either have been lost to mining or are yet to be mined. These deposits have different origins. Some formed along shorelines at the heights of marine transgressions while others formed on regressional beach ridge plains during periods of temporary stillstands or slight transgressions. These different origins are reflected in the chemical and physical characteristics of the deposits. Ilmenite in older, more western deposits has a higher TiO2 content than ilmenite in younger, more eastern deposits. TiO2 content does not very with north-south direction. Garnet and epidote are absent or rare in the older Trail Ridge deposits, but progressively become common in the younger Duval Upland, Crestal Pamlico, and Holocene deposits. Grain size is coarsest for Trail Ridge sediments and finest for sediments in Duval Upland and Crestal Pamlico deposits. The average grain size for Holocene deposits is intermediate between Trail Ridge and Duval Upland deposits. The two models for the origin of the heavy-mineral deposits – deposits formed at the height of major marine transgression; and deposits formed during periods of temporary stillstands or slight transgressions that occur during a general marine regression; - are consistent with known sedimentological data and depositional trends.

Jan 1, 2005

By C. Feng, W. Song, B. Moudgil, P. Zhang, W. Xiao

Separation of dolomite from phosphate is the most challenging problem in phosphate mineral processing. Over 50% of the future phosphate reserves in Florida contains too much dolomite to process using the current industry practice. The FIPR Institute has collaborated with worldwide experts in the field to address this issue. As a result, the industry is now offered with three feasible options. Optional 1 involves crushing and grinding of high-dolomite phosphate pebbles followed by dolomite flotation at slightly acidic pH using a new collector that does not require phosphoric acid as a phosphate depressant, achieving a final concentrate analyzing less than 0.9% MgO at about 87% P2O5 recovery. Option 2 offers three methods for reducing MgO content in the concentrate from the Crago process, including adding a dolomite depressant in the rougher flotation step, dolomite flotation of the cleaner concentrate, and scrubbing the cleaner concentrate in quartz sand. These methods could reduce MgO content in the final concentrate by 20-40%. Option 3 is a gravity separation technique using an innovative separation jig, and may well be the ultimate solution to the problem. INTRODUCTION Magnitude of the Dolomite Problem With the depletion of the higher grade, easy-to-process Bone Valley deposits, the central Florida phosphate industry has moved into the lower grade, more contaminated ore bodies from the Southern Extension. The phosphate deposits in the Southern Extension may be divided into two zones: an upper zone and a lower zone. The upper zone is readily processable using the current technology, but the lower zone is highly contaminated by dolomite. Geological and mineralogical statistics (Hassan and Bogan, 1994) show (Table 1) that more than 50% of the phosphate resource would be wasted if the lower zone is bypassed in mining, and about 13% of the resource would be wasted if the dolomitic pebbles in the lower zone were discarded.

Jan 1, 2019

By C. K. Kocsis, S. Hardcastle

Mine ventilation, requires electricity to operate the fans and fossil fuel for heating. Typically, this accounts for approximately 40% of the overall underground energy consumption. This is considerable, and one of the major causes of this expense is that most mine ventilation systems are designed for the "worst-case-scenario" with respect to ventilation demand, which is commonly dictated by diesel equipment usage. Once designed, mines tend to operate their ventilation system at this peak level despite their exceeding day-to-day development and production needs due to lack of appropriate ventilation controls. In underground metal mines, TeleminingTM, which includes the tele-remote operation of mobile development and production equipment from surface, will change the mine design criteria including its support infrastructure such as the ventilation system. With the removal of machine operators to surface control rooms, conventional ventilation systems designed to dilute and remove pollutants can become redundant. Depending on the ultimate need for ventilation, its cost in automated mines with tele-remote equipment operated from surface will be lower than the cost of ventilation in conventional mines. These cost savings, which could be significant, would not only come from the ability to reduce the amount of ventilation in the mine, but also through the capacity to automate its distribution. This paper provides an indication of the new airflow requirements in stopes and dead-end developments for the tele-remote and automated mining processes based on climatic modelling. Furthermore, this paper makes a cost benefit analysis by comparing the ventilation system operating cost of a conventional underground metal mine based on the mobile diesel powered equipment design criteria with the newly redesigned ventilation system operating cost of an automated mine based on the "heat management" design criteria.

Jan 1, 2002

By R. L. Virta

Sixteen companies mined fuller’s earth in 11 states during 2004. Production during 2004, based on a preliminary survey of fuller’s earth producers, was 3.96 Mt (4.3million st) valued at $340 million. This compared with3.6 Mt (3.9 million st) during 2003, valued at $346 million. The 3.96 Mt (4.3 million st) probably includes some crude clay tonnage. And production of finished product probably was closer to 3.2 Mt (3.5 million st) in 2004. Georgia was the leading producer state of attapulgite-type fuller’s earth, followed by Florida. Georgia also was the leading producer state for montmorillonite-type fuller’s earth. It was followed, in descending order, by Mississippi, Missouri, Florida, Virginia, Illinois, California, Tennessee, Kansas and Texas.

Jan 1, 2005

By Jesse H. Auvil

In January of 1966, during the annual session of Georgia's General Assembly, Representative Paul E. Nessmith of Statesboro, Georgia, walked into my office and asked me what I thought of the advisability and feasibility of a law which would require the mining operators to reclaim their mined out lands. My answer to him was, as a one time mine superintendent and operator, that I probably would not think very highly of the added cost which reclamation would impose on the operation; but that since assuming the job of Chief Geologist and Assistant Director of the Georgia Department of Mines, Mining and Geology, and in retrospect, I could recommend it very highly, particularly in view of the increased pressure being applied by the Federal government along these lines. I stated then and still emphatically state that this sort of administration should be done on the State level rather than the Federal level. He asked me if I would conduct him on a tour through some of the mining country in which I had worked and to this I readily agreed. The result of this trip was that he was adversely impressed by the devastation which the mining operations had wreaked on that area of middle Georgia along the fall line known as the kaolin belt. Very little except talk was done for the remainder of 1966.

Jan 1, 1970

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 Andrew Stafford, Kate Willa Brown Requist, Eric Lutz, Simon Lotero Lopez, Moe Momayez, Jeffrey Gordon

This formal literature review identifies strengths and shortcomings of current literature related to mine rescue, self-rescue, and self-escape technology. Key concepts and factors that influence the decision making behind mine rescue and self-escape were identified. Historically, underground mining has been one of the most dangerous occupations due to the harsh nature of working environments. During the latter half of the twentieth century, and into the twenty-first century, mining fatalities have declined, yet large-scale mine emergencies persist. The emergence of new technologies, in combination with evidencebased mine emergency research, is resulting in new training methods, monitoring systems, and self-escape approaches being tried in operating mines. This review identifies areas in which substantial research is being conducted, such as the use of virtual reality and game-based training and areas that warrant further development such as the measurement and information gathering capabilities of unmanned ground and aerial vehicles, as well as emergency management and incident command systems. This paper summarizes the current underground mine rescue and self-escape landscape in the USA, including the breadth and depth of mine rescue and self-escape training and practices as evident in the literature.

Nov 2, 2023

By R. Reeves

Coal producers and utilities depend on automated coal blending systems to reduce costs and meet stringent environmental regulations. Over 30 systems installed in the United States since 1987 use on-line PGNAA (Prompt Gamma Neutron Activation Analysis) analyzers to accurately control the blending process. Experience and detailed engineering are required to integrate real-time data produced by the coal analyzer with a control system to meet demanding performance specifications. This article reviews successful installations and lists important features including interfacing analyzers with plant control systems, specifying feeders and weigh scales, and managing data.

Jan 1, 1995

By C. Bryce

Rhenium is primarily recovered as a byproduct from molybdenum roasting circuits. However, rhenium is also present in copper heap leach solutions at very low concentrations, and this represents a potential new rhenium source. Freeport-McMoRan (FCX) has developed a new process using carbon adsorption followed by ion exchange or solvent extraction to concentrate rhenium from less than 1 ppm to 15 g/L. The product is compatible as a feed to an existing rhenium processing plant. A pilot plant operated at Freeport-McMoRan?s Sierrita Mine has demonstrated the technical and financial feasibility of this new process. Copper heap leaching dissolves more than just copper from the copper ore. Several metals can be identified in leach solutions at concentrations of financial interest, rhenium in particular. Rhenium spot prices ranged from a yearly average of $1,070/kg ($483/lb) in 2005 (Magyar, 2008) to $10,400/kg ($4,706/lb) in 2008 (Polyak, 2013). The spot price in September 2013 was approximately $3,000/kg ($1,357/lb) of rhenium (Metal Bulletin, 2013). Several facilities at Freeport-McMoRan have very low rhenium concentrations in their copper leach solutions, ranging from 0.1 to 0.7 mg/L. The large quantity of solution available, if coupled with an attractive rhenium price, means that the rhenium contained in leach solutions may represent a significant value if a method of extraction could be developed. Testing has confirmed that rhenium adsorbs onto activated carbon much more selectively than other metals in the pregnant leach solution (PLS). A 100-gpm pilot plant was constructed to verify the lab-scale results on a larger basis and establish operating parameters for a full-scale operation. This report summarizes the initial technology development and pilot plant operation.

By Clyde L. Smith

Since the early 1950's exploration in the Yukon Territory, Canada, has been confined largely to Selwyn basin where at least five large stratiform or massive sulfide Pb-Zn deposits have been discovered. The five ore bodies total nearly 100 million tons of 10-16% combined Pb-Zn with 1-3 oz./ton Ag. The only deposit currently in production is the Anvil Mine operating at 8,000 tons per day. Beginning in 1972, exploration in the Mackenzie Mountains, east of Selwyn basin and west of Mackenzie arch, resulted in finds of Mississippi Valley type Zn-Pb mineralization in a belt of Proterozoic and Lower Paleozoic carbonate rocks (Figure 1). Four districts have been located and intensive exploration by numerous Canadian and Arnerican mining companies is currently in progress over a length of 400 miles in the carbonate belt. The consensus is that a major new Zn-Pb province may be taking shape.

Jan 1, 1974