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By W. F. McDermott

One of the major improvements in ore grinding economics in North America has been the introduction of autogenous grinding. The history of this has been well documented in previous AIME presentations and in the literature. Pickands Mather & Co. has been very active in the development of autogenous grinding since 1957. This early work led to the application of autogenous grinding to the Wabush Mines ore in 1965, with the installation of 6-24 ft. diameter by 8 ft. long - 1,750 HP mills. Development work recently completed in 1971 on another ore has led to the decision to install 5-36 ft. diameter by 15 ft. long - 12,000 HP mills when this project goes ahead. Between these two decisions lies a tremendous amount of research, development, and application of autogenous grinding to a variety of ores. The Pickands Mather Metallurgical and Research Laboratory in Hibbing, Minnesota has tested, in its pilot plant facility, ores from 9 different deposits. Some of these deposits have as much difference within their own ore types as there is between the various deposits. Therefore, it is safe to say that over 20 different ore types have been tested and flowsheets developed for commercial applications. Of the 9 projects, 3 are in operation. These are Wabush Mines in Labrador, Canada, (1) Savage River Mines in Tasmania, (2) and The Griffith Mine in Red Lake, Ontario, Canada. (3) Pilot plant work has encompassed over 300 individual tests. These tests were carried out in mills that were 5-1/2, 8, and 12 ft. in diameter. Grinding power requirements for the primary autogenous milling has varied from 2 to 30 KWH/Lt of crude ore.

Jan 1, 1972

By A. Davaliev, K. Hrkovic, V. Pavlovic

On the territory of Macedonia in South Yugoslavia primary and dory gold occurences were known since ancient times. Remnants of numerous goafs and remainders of washaries on river terraces and alluviums date right back to the times of Phillip II and his son Alexander of Macedonia and from Roman times, as well as from the Middle Ages witness exploitation of primary and secondary gold. More recent explorations on primary and secondary gold occurrences date from the period between two World Wars. Over that period a number of private companies, each on their own jointly, carried out gold exploration, particularly of alluvial occurrences on rivers emptying into River Vardar, starting from Skopje to the Greek frontier. The latest gold explorations carried out In the alluvium of River Konjska date back in 1976, and in 1978 old terraces of River Konjska were explored. The Visibility Study was prepared on possibilities of exploitation of gold from River Konjska alluvium. In the paper are collected the basic date an all known primary and secondary occurrences of gold, the results of the latest explorations, and the study itself. To-date geological explorations and analyses show very interesting potentionality of River Konjska and River Vardar alluvium, which proves continuing of he further explorations. For the moment, it is necessary to re-explore more complete view of the deposit. After that it will be possible to make complete techno-economical estimation of the auriferious alluviums and the conditions of the evaluations of the alluvial gold. 1. REVIEW OF PRIMARY AND SECONDARY GOLD DEPOSITS IN MAOEDONIA,YUGOSLAVIA 1.1. Primary deposits Scarse data are available for primary gold deposits in Macedonia` being unadequate for clear

Jan 1, 1988

By Joseph A. Kantor

Several wall rock porphyry or pyrometascmatic copper deposits occur within the metamorphosed Paleozoic formations along the northern and eastern flanks of the Little Dragoon Mountains. Rocks ranging in age from Precambrian to Recent occur in the area. The Tertiary age Texas Canyon Quartz Monzonite intruded the sedimentary section in the eastern half of the range metamorphosing the Paleozoic carbonate units to tactites composed of garnet, diopside, and tremolite. Copper, zinc, and molybdenum minerals deposited in sites which are structurally controlled and stratigraphically favorable. Because the deposits are covered by alluvium, the information on structure, alteration, and mineralization is based upon a study of the diamond drilling programs. The mineralized district can be divided into four areas: 1) The Johnson Camp copper-zinc deposits; 2) The Dragoon copper deposit; 3) The I-10 copper-molybdenum deposit; 4) The Strong & Harris copper-zinc deposit. On the southwest end of the range beneath alluvial cover, the Cretaceous Bisbee Group was thrust over Precambrian and Paleozoic formations. The Tertiary Texas Canyon Quartz Monzonite intruded and metamorphosed them. In the upper plate, the Cretaceous sediments near the intrusive were metamorphosed to metaquartzite and andalusite and sillimanite schists. In the lower plate the Martin and Horquilla formations were marbleized. The lower Abrigo was metamorphosed to epidote rich calc-silicate tactites and biotite hornfels. A composite geologic cross section, based upon diamond drilling,, through the Dragoon copper deposit is shown in Fig. 1. The geologic events which formed this deposit are: 1. A faulted section of Precambrian Pioneer formation and diabase and Cambrian Bolsa and Abrigo formations was thrust over Pennsylvanian Horquilla formation. The Dripping Spring quartzite if present, has not

Jan 1, 1977

By R. H. Smith

The total energy demand in the United States increased about 4 per cent annually during the 1960's 1 and is expected to increase at the same rate during this decade. Z Fuel oil growth in the 1960's was only Z per cent per year until 1968, but it increased to 8 per cent in 1969 and 11 per cent in 1970. Fuel oil demand is expected to grow at a 6 per cent rate through the 1970's. Part of this rapid increase in demand has been caused by restrictions placed on the sulfur content of fuels. High sulfur coal can no longer be burned in many parts of the country and has been replaced by low sulfur fuel oil. An insufficient supply of natural gas has also contributed to fuel oil demand. Air pollution regulations have not only caused an increase in fuel oil consumption, but they have also caused a reduction of sulfur content in residual fuel oils. Current regulations call for 1 per cent maximum sulfur content fuels over much of the country. Sulfur contents of fuels are limited to 0. 3 per cent in certain areas on the east and west coasts. Sulfur in residual fuel oils from high sulfur imported crude oil is reduced to 1 per cent currently. However, sulfur reduction to 0. 3 per cent is difficult and expensive.4 As a result, refiners may be hard pressed to supply the market for low sulfur fuel oil. The oil shale deposits in Colorado and Wyoming potentially are a huge source of low sulfur fuel oil. It will be shown that the low sulfur content and more importantly the sulfur

Jan 1, 1972

By D. Berberick, G. Sturgis, M. Board, B. Strickland

"Hecla Limited is nearing completion of the Lucky Friday Mine No.4 shaft located in Mullan, ID. The shaft is collared at the 4940 level of the mine and will have a final mine level depth of 8620, or 9,590 feet below the surface. After reaching the 7400 mine level the shaft encountered ground deformation higher then allowed for in the design for a circular shaft excavation and concrete lining. This additional ground deformation required portions of the shaft concrete liner to be reinforced with frameless, steel liner plate. To eliminate the installation of the liner plate from the remaining shaft development, the design of the shaft excavation starting at the 7650 mine level was changed to an elliptical cross section based on the overall stress field orientation as well as the orientation of the structure of the host rock surrounding the shaft. The elliptical cross section was instrumented to confirm the shaft excavation and lining was performing as designed. This design change has allowed the shaft to continue to the planned 8620 mine level without the need to install liner plate in the shaft or change the overall functionality of the shaft or the Lucky Friday life of mine plan.INTRODUCTION Hecla’s Lucky Friday Mine is a deep, underground producer of silver, lead and zinc in the Coeur d’Alene mining district of northern Idaho (Figure 1). Primary access into the mine is via the Silver Shaft, a 5.5-m (18-ft) diameter, concrete lined shaft sunk to an original depth of 1,890-m (6,200-ft). Current production is from the Gold Hunter vein system, approximately 1,525-m (5,000-ft) northwest of the Silver Shaft.Lucky Friday’s #4-Shaft is a 5.5-m (18-ft) finished diameter, internal shaft, or winze, being sunk to the north of the Gold Hunter vein system, from the mine’s 4760 level, 1,743-m (5,720-ft) below the surface, to the 8620 level, 2,923-m (9,590-ft) below the surface. The shaft is designed to provide access to the deep, high-grade zones of the Gold Hunter in order to increase the mine’s production and operational life. Design and engineering began in 2006, with construction starting in the fourth quarter of 2009."

Jan 1, 2016

By S. A. Hoenig

Introduction In an earlier publication, the application of exoelectron technology to the monitoring of dry grinding in a ball mill was reported. Recently, the author has investigated the ball mill problem in more detail with the system shown in Fig.1 . Here, some of the current generated in the ore-ball-water mixture was picked up by the metal chains and served as a measure of the rate of grinding. While the mechanism of current generation has not been completely clarified, a parallel study of electrical effects associated with rock drilling indicated that the major driving force is the zeta potential*, while oxidation of the freshly fractured material provides the remainder of the current. Both of these effects are sensitive to the exposed surface area, and it might be expected that the observed currents would provide a measure of the grinding rate. This "surface area" effect allows the measurement system to be used in any type of rock or ore grinding. Some studies with sulfide copper ore indicate higher currents than those observed with silica sand, but the overall pattern of current versus grinding rate is essentially the same. Experimental Studies The experimental system was set up as shown in Fig. 1. The initial studies were done with silica sand because of its availability and for comparison with the data of reference 1. The sand was sized to an average of 425 µm (40 mesh); a typical charge consisted of 2.5 kg (5.5 lb) of sand, 0.85 L (0.22 gal) of tap water and 2.5 kg (5.5 lb) of iron grinding balls 25.5 mm (1 in.) in diameter. For a typical "run," the mill was loaded with a fresh charge of ore and operated for periods ranging from 10-60 min. During this time, the current was measured with a Keithley 417 picoammeter and a chart recorder. At the end of the grinding period, the charge was removed and sieved to recover the 425, 300, and 212 pm (40, 50, and 70 mesh) fractions which were then drained and weighed. A fresh charge was used for each test and every attempt was made to keep the draining and weighing processes uniform. *The zeta potential is the voltage developed between the surface of a solid particle and the ion solution in which it is immersed. In the case of rock/ore materials in water, the zeta potential is negative.

Jan 1, 1984

By Fathi Habashi

THE CHOICE of a precipitant for a certain metal ion depends, beside the economic factor. on the following factors: 1) The precipitant should be specific as far as possible so that pure precipitates can be obtained

Jan 1, 1970

By J. Sulaiman Lubis

Indonesia is a developing country in Southeast Asia with a population of some 180 million people. It has a stable political environment and currently enjoys high rates of economic growth. Indonesia has abundant reserves of natural resources, ample for its own needs and for export. Energy resources include oil, gas and coal. The oil and gas industries are well established domestically and for export. In the last few years, though, coal industry development has been rapid. Coal resources from bituminous to lignite amount to more than 30 Gt (33 billion st). That is more than enough to meet domestic needs and provide significant amounts for export. Figure 1 shows coal basins in Indonesia. Coals in Indonesia are generally young steaming coals. They are very low ash and sulfur, high volatile, bituminous B and C. The Indonesian government's state coal company is called Perum Tambang Batubara. The company has actively promoted the development of its coal for domestic and export markets. In particular, the government has placed priority on non-oil exports of which coal is a major element. The government strives to honor all contractural commitments for the export of Indonesian coal from contractor, private and government mines. From 1987 through 1989, coal production has increased from about 3 Mt (3.3 million st) to 9 Mt (9.9 million st). Exports have grown from I Mt (1.1 million st) to 3 Mt (3.3 million st). These are significant increases for a small industry with limited infrastructure. But with growing investment and development, these production and export levels will increase substantially, and Indonesia will be a significant world supplier of coal in the 1990s.

Jan 1, 1990

By J. C. Norman

The boron review arrived too late for the June issue. The United States was the world's largest producer and consumer of boron compounds during 1993. Boron mineral concentrate and chemical production in the United States totaled an estimated 958 kt (1.05 million st), yielding 526 kt (580,000 st) of B203, according to the US Bureau of Mines. Estimated value was $322 million. This level of production was about 5% less than 1992 revised production figures. The United States continued to provide essentially all its own boron while maintaining a strong position as a source of sodium borate products and boric acid to foreign markets. Domestic employment in the mining and beneficiation of boron products in 1993 was 900 people, about the same as in 1992. That was down from 1988 levels of 1250 people. Total world production of boron in 1993 was about 2.5 Mt (2.75 million st), yielding about 1.2 Mt (1.3 million st) of B203. World production in 1993 was about equal to revised 1992 levels. Production United States In 1993, mines and processing operations in southern California were the only domestic sources of boron mineral concentrates and chemicals. Domestic producers, in order of quantity of production, were: • US Borax and Chemical Corp., which operates an open pit kernite and tincal mine at Boron, CA, producing boric acid and borax products, • North American Chemical Co., which produces boric acid and borax products as coproducts from chemical operations at Searles Lake, CA and • American Borate Co., which produced small amounts of colemanite and shipped from inventories from its operation in Death Valley, CA.

Jan 1, 1994

By Stanley C. Suboleski, C. B. Manula

INTRODUCTION In any mining operation all possible steps should be taken to increase efficiency. One area for improvement is mine planning and design, particularly in the area of equipment selection for room-and-pillar systems. Be- cause of the availability of a wide variety of face machines, a fair degree of selectivity can be exercised in the choice of equipment for a particular job. However, this choice must be made on the basis of quantitative facts and forecasts related to the mining application. The purpose of this section is to develop and analyze the details of the mining process. Some specific areas studied include the relationship of system design to productivity, suboptimization as a result of equipment changes, and measurement of system performance. The plan of work leading to a quantitative description of these study areas is based on the growing interest in total system design using simulation as an analytical method (Manula, 1963). CHARACTERISTICS OF PRODUCTION OPERATIONS FROM ROOM-AND-PILLAR SECTIONS For a given mining method, raw production in a given section of a mine is primarily dependent upon the coal seam thickness, roof and floor conditions, methane emission, the mining methods, and the man-machine element. Average section production varies from 300 to 800 st per shift for conventional and continuous mining in high seams and from less than 100 to 300 st per shift in low seams. Since the reject varies from 0 to 40%, these figures must be decreased by the appropriate percentage to reflect the amount of clean coal mined. Personnel requirements per production section per shift for the various methods are listed in Table 1. Table 1. Production Personnel Method No. Method No. Conventional 12-1 5 Longwall 9-14 Continuous 9-1 2 Shortwall 9-12 MINING VARIABLES To evaluate the constraints and interrelationships for various mining methods, it is necessary to categorize the variables which underlie system production potential. Seven critical independent variables which determine production can be identified and categorized (Suboleski, 1978) : Seam Height The five categories are as follows: less than 36 in.;. 36 to 55 in.; 55 to 100 in.; 100 to 180 in.; and greater than 180 in. Floor Quality Floor quality ranges from : Excellent: Smooth, hard, grades less than 1 to 1 % % , and dry. Good: Smooth, soft but dry, with grades less than 3 % . The floor will deteriorate, but cautious operation can prevent it. There may possibly be heaving at some later time. Fair. Soft and damp. There is occasional interference with equipment operation; requires the use of four-wheel drive shuttle cars; ruts with regular use, and may have adverse grades of 5 to 7%. This may be coupled with slippery bottom and/or occasional steep rolls. Poor: Soft and wet. Requires blocking of the bottom to support equipment. There are frequent steep rolls and grades in excess of 7%. Roof Quality Roof quality ranges from : Excellent: Men are able to work under the unsupported top during the initial production cycle if legally permitted. Good: The roof is bolted on a 4 x 4 or 5 x 5 pattern with short bolts (442 in.) or <seam height if the seam >42 in., or requires posting with no bolts on a 4 x 4 or 5 x 5 pattern. There are no falls. Average: The roof is normally bolted on a 4 x 4 or 5 x 5 pattern, but with long bolts (>seam height or >6 ft.). There are infrequent minor falls or there may be an excellent roof which is difficult to drill. Fair: This type often requires spot bolting in addition to the regular pattern or bolting with planks. The roof conditions require shorter than planned cuts, or narrow cuts. Poor: This type requires bolts plus crossbars and posts, or installation of yielding supports or truss-type support. It is almost certain to fall if this is not done. Methane Liberation This ranges from none detected to low (no buildup at the face, even with minimum ventilation requirements) to moderate (the curtains must be extremely tight and tubing close to the face or methane will build up to 1 % during the loading of the car) to high (methane will build up to 170 if the miner is operated at the normal rate, even with proper ventilation). Hardness of Coal Coal hardness falls into the following categories: Soft: Soft coal is easily cut by a continuous miner. A plow could be used by longwall. Average: Coal of average hardness could be easily cut by a miner, and a shearer would be used in the longwall. Moderate: Moderately hard coal causes difficult cut-

Jan 1, 1982

By Clyde L. Smith

Since the early 1950&apos;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

By Stanley O. Reichert

At nuclear facilities, three types of radioactive waste must be managed: (1) high-level liquid waste containing fission products from the chemical separation of irradiated uranium, (2) low-level condensates from the concentration of the high-level waste, and (3) dry solids such as obsolete process equipment, spent ion exchange resins, and irradiated metal scrap. The geological and environmental characteristics of a site are important considerations in planning the waste management program. At the Savannah River Plant, low-level liquids and dry solids are safely and economically placed in the soil where the geologic and hydrologic conditions are favorable. Within the general area where the waste originates, studies are made to locate seepage basins and burial grounds in the most favorable sites: (1) soils should have a high ion exchange capacity and moderate to low permeability, (2) the water table should be deep, and (3) burial sites should be relatively distant from the nearest flowing stream.

Jan 1, 1968

By Eugene P. Pfleider

The mining industry of the World, and particularly of the United States, has made a complete reversal from underground to surface mining methods since the turn of the 20th Century. This has occurred even as average ore grades were decreasing and strip ratios rising. In the early 1900&apos;s there were over 100 underground mines producing from the three iron ranges of Minnesota -- today there are hone. Practically all of our coal prior to 1930 was mined underground; today over one-third is from surface operations and that percentage is increasing. Although world mining has hot changed to surface techniques as rapidly as has the U. S. Industry, the shift is escalating and will approach our figures shortly. A comparison of World and U. S. production figures are shown in Table 1, taken from the AIME Surface Mining volume, and the trend rates for the U. S. are depicted in Fig. 1.

Jan 1, 1968

By Joseph K. Cavey

To accommodate the new Pier A expansion at BWI airport, a 1.8 m (6.0 ft)diameter stormwater pipe was constructed below active Runway 15R-33L. The jacked tunnel alignment runs east/west below the runway, and the depth the crown was 6.1 m(20 ft). Soil conditions consisted of very loose to medium sand and gravel, with some medium stiff clay and silt. Super Jet Grouting was selected as the ground treatment system, creating large diameter columns. All work was performed from the surface of the runway between the hours of 12 am and 6 am. Monitoring points along the tunnel in the grout zone indicated zero settlement during tunneling. Tunneling operations in front of and beyond the treatment zone experienced significant settlement. Super Jet Grouting in the treatment zone provided a low permeability continuous stable soilcrete that was readily mined while the runway remained in service.

Jan 1, 2003

By R. G. Swanton

The Bureau of Mines is investigating the leaching of phosphate values from Florida phosphatic clay wastes using sulfuric acid (H2SO4) as the leaching agent and methanol as the solvent. Acid-alcohol leaching studies were done using pure crystalline apatite to investigate potential causes for low extractions. It was found that a barrier layer formed on the surface of the apatite. Initial discovery of the barrier layer was made by analyzing pure apatite samples before and after leaching using an optical microscope. Subsequent Fourier Transform Infrared (FT-IR) analyses proved the coating was calcium sulfate hemihydrate (CaSO4-1/2H2O) and that unreacted apatite existed beneath the coating. Scanning electron microscope (SEM) photographs depict the CaSO4-1/2H2O morphology as long slender crystals adhering to the apatite surface. It was also shown that grinding the leached tailings and leaching again in the H2SO4-methanol system resulted in additional phosphate extraction.

Jan 1, 1991

By George R. Mitchell

It is a common observation that objects having, different; temperatures exchange energy by radiative transfer. The quantity of radiant energy emitted by an object is a definite function of its temperature. Therefore, a measurement of emitted radiation, by means of a calibrated radiometric instrument, provides a temperature measurement without contacting the emitting object. The physical laws describing radiant energy transfer and their application to remote temperature measurement form the substance of this paper. The energy radiated by bodies having temperatures up to 4000°C is largely in the infrared spectral region. The infrared spectral region is that part of the electro-magnetic spectrum having wavelengths longer than visible light and extending to the microwave region. The wave-lengths range from 0.7 micron (1 micron = 10-4 cm) to 1000 microns. In general, infrared radiometry deals, with the methods of measuring energy flux in the 1 to 15 micron region of the infrared spectrum.

Jan 1, 1960

By Adrian Smith, Debra W. Struhsacker

There is now overwhelming evidence that, despite concerns to the contrary, natural degradation of cyanide and cyanide attenuation by hydrogeochemical processes are capable of minimizing or eliminating potential water qua1ity impacts from heap leach systems. A1 though there was some recognition of these data by the regulatory authorities, for example the initial USEPA modification of cyanide standards to an advisory level, many states have codified standards inappropriate to the clearly site specific nature of heap leach operations. As an overview to this problem, this paper will integrate the theoretical chemical data on cyanide with the observed geochemical behavior of cyanide in the decommissioned heap leach environment. The cyanide species that are likely to exist within an abandoned heap leach system will be identified, and the relative toxicity and potential environment effect of these cyanide species will be discussed. These data will then be used to evaluate cyanide detoxification regulations for decommissioned heap leach projects in 14 states.

Jan 1, 1987

By R. Hogg, T. F. Dumm

A simple shape description scheme has been developed which has the specific aim of distinguishing between angular and more rounded particles. The procedure involves fitting a general polygon (usually about 20 sided) to the particle profile. Geometric shape descriptors have been defined based on variations in the angles between adjacent sides and their radial displacement from the particle centroid. A two-parameter shape description, incorporating an angular variabli1ity and an elongation index, has been shown to be clearly consistent with visual observations. A single-parameter angularity index has been shown to be very sensitive to small differences in particle roundness and seems to provide a better description of angularity than other approaches such as signature and fractal analyses. The scheme has been applied to three sets of fine quartz particles produced by different grinding procedures. The results indicate that the technique is capable of distinguishing between angular and re1atively rounded particles and can quantify their specific shape features.

Jan 1, 1991

By J. E. Hoffman, S. P. Sandoval, T. J. Keefe, K. P. V. Lei, O&apos

The U.S. Bureau of Mines investigated the use of the Fe2+/Fe3+-SO2 (FFS) anode reaction in the copper leaching-solvent extraction-electrowinning circuit. The investigation revealed that six process variables, including anode type, Fe 21 concentration, current density, electrolyte temperature, degree of agitation, and manifold injection point were found to influence cell voltage and cell current efficiency. A 47% voltage reduction (0.8 versus 1.5 V) compared to conventional electrowinning with activated lead (ALE) anodes was achieved at a current density of 258 A/m2 (24 A/ft2) with an industrial electrolyte. Current efficiency was maintained above 90%, and S02 above the cell measured less than 1 ppm when activated carbon was used to assist the reduction of Fe" by S02 in the copper electrolyte. Solvent extraction tests showed that Alamine 336 is a stronger H2SO4 extractant than is needed to extract the excess acid produced by the FFS anode reaction.

Jan 1, 1993

By Jean-François Boucher, Ernest K. Yanful, Mei Lin Shelp, Lionel J. J. Catalan

Shallow water covers for preventing acid production in tailings are based on the principle of minimizing oxygen availability. Resuspension of material from the tailings bed may result in increased oxidation and metal releases since dissolved oxygen is at near saturation levels in the water cover. Resuspension can be caused by waves and currents strong enough to mobilize the surface of the tailings bed. Tailings resuspension was measured with sediment traps in the Upper Cell of the Heath Steele site near Mirarnichi, New Brunswick Canada. Although significant amounts of resuspended tailings were collected in all traps, analysis of resuspended solids and bed tailings suggests that for the observed wind conditions resuspension did not occur at locations where the water cover depth was greater or equal to 1.0 m. Currents were likely responsible for the transport of resuspended tailings from shallower areas to locations where the water cover was deeper than 1.0 m.

Jan 1, 2000