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By Fathi Habashi

CRYSTALLIZATION from aqueous solution is a simple and old method for the recovery of metal values from leach solution. Practically all the methods for the recovery of aluminum from clay are based on the crystallization of an aluminum salt from the leach solution. Differences in solubilities may be used to advantage for separating two metals from the same leach solution. The classical method of Marignac (1866), which makes use of the difference in solubilities of K2TaF7 and K2NbOF5 to separate niobium from tantalum, has been used successfully in the manufacture of these metals (Fig. 10-1). The slurry containing the metal oxides is dissolved in 70 % hydrofluoric acid, diluted, and heated near boiling. A potassium salt is added in sufficient quantity to form the complex fluorides of the niobium and tantalum present. The solution is filtered and allowed to cool. At room temperature most of the tantalum salt crystallizes out while the niobium remains in solution.

Jan 1, 1970

By J. K. Phiri

Copper mining is the main activity in Zambia and is confined to the large scale operations, mainly on the Copperbelt. The Copperbelt covers an area of size l00km by 50 km with a total of 10 underground and 5 open-pit mines operated by Zambia Consolidated Copper Mines (ZCCM) Limited. Most of the operations in these mines involves drilling and blasting. The loading of broken materials is by both manual and mechanical operations. Among the many risk factors associated with mining on the Copperbelt, is the occurrence of Pneumoconiosis which in the recent past has become quite prevalent and thus an important occupational health hazard for the industry. This study was carried out with the aim of establishing trends of pneumoconiosis incidence through the annual data collected by Pneumoconiosis Medical and Research Bureau of the Ministry of Health in Zambia, so that a basis could be formed for future research work. The study covers over 1,000 certified cases of Pneumoconiosis between 1960 and 1990

Jan 1, 1993

By Robert L. Cascio

The mining industry uses a large amount of electric power. Their equipment is subject to extreme environmental conditions and mechanical shock. A significant number of electrical accidents are a result of improperly grounded electrical equipment. Federal regulations require the safety ground bed resistance to be measured once a year or after modifications. Most commercially available instruments used to measure the ground bed resistance require the ground conductor to be disconnected and the power system disconnected for safety reasons. The "fall of potential1' method requires auxiliary ground rods and approximately two hours to complete the test. Although a new instrument was initially thought to measure the ground bed resistance immediately without isolating the ground bed, field tests have shown this method is not accurate. In some cases, a continuous measurement of the ground resistance is desired. A monitor has been developed and is presently being evaluated at several mines. These installations will be discussed.

Jan 1, 1992

By John E. Urosek, Mark L. Mott, Gary E. Smith

One function of Mine Safety and Health Administration (MSHA), Pittsburgh Health Technology Center's Ventilation Division is to provide assistance to MSHA enforcement and industry personnel for maintaining adequate fresh air to all areas of an underground mine. In fulfilling this objective, total mine venti1ation pressure-air quantity distribution on investigations are conducted to measure the air pressures and quantities necessary to describe and analyze the existing ventilation systems. Various ventilation parameters are calculated from these measured pressures and quantities. Some of these parameters are: pressure drop in intake and return airways, air leakage, percentages of air reaching active sections, average regulator drops, and fan pressures. The purpose of this paper is to present and compare values of ventilation parameters calculated from investigations at twenty underground coal mines.

Jan 1, 1987

By Ahmet Gursoy

Maryland, will be the widest vehicular tunnel ever built by the trench tube method. Careful coordination and planning were required to meet the tight and fast design and construction schedules. During the preliminary design, traditional design drawings were bypassed in favor of 25 preliminary design reports representing major work breakdown structures (tasks). For each task, alternative design solutions were examined and analyzed by means of trade-off studies on the basis of engineering, constructibility, and economic considerations, thus providing an overall conceptual value engineering approach for the entire project. So far, total value engineering proposed by the contractor for Contract I I (largest contract of the project at $245 million) is less than 1.5 percent of the contract value. This is an important indication of the success of the design phase planning.

Jan 1, 1983

By Christof Brewka

Los Pelambres, 200 km north of Santiago, Chile, is the latest in a series of mega-projects developed in this part of the world. While most of its predecessors are spread over open desert, the Los Pelambres mine is nestled inside a narrow alpine valley high in the Andean Mountains. To handle the daunting task of transporting the mined copper ore more than 12 km and 1,400 vertical meters downhill to the concentrator plant, a gigantic belt conveyor system (capacity of 8700 mtph, 1800 mm wide ST 7800 steel cord belt, 2.5m diameter pulleys, an elaborate braking system including a mechanical failsafe and large reducers with a total installed drive power of 25,000 kW) has been employed. Many of these components have pushed the limits of conventional belt conveyor design.

Jan 1, 2000

By Allan E. Koski

Michigan is the second largest iron ore producing state in the United States. The Empire Mine, celebrating its 30th anniversary in 1994, is the largest iron ore mine in the state. The Empire Iron Mining Partnership is an iron ore mining, concentrating and pelletizing facility managed by The Cleveland-Cliffs Iron Co., a subsidiary of Cleveland-Cliffs Inc. The Empire Mine is located near Palmer, MI on the Marquette Iron Range in Michigan's Upper Peninsula. The partnership includes Inland Steel Co., LTV Steel Co., Wheeling-Pittsburgh Steel Corp. and Cleveland-Cliffs. Mine construction began in 1960. The first pellets were produced in late 1963. Successive expansions in 1967, 1974 and 1979 resulted in Empire reaching a present annual capacity of 8.1 Mt (8 million long tons) of pellets. In late 1993, a milestone was reached with the production of Empire's 152-Mt (150-millionth long ton) of iron ore pellets.

Jan 1, 1994

By James R. Piper

Cumulophyric feldspars, of varying morphology, carry myrmekitic quartz interstitially between microperthitic feldspar lamellae. The size, coarseness, and morphology of these crystals, together with concordant foliation features constitutes evidence that they are a product of primary crystallization, formed prior to eruption from a vent. These crystals occur preferentially along 2 - 5 mm thick tan, vesicular to compressed alteration bands intercalated with more densely welded light grey bands. In perlite with quartz at or below a 0.1% threshold, megascopic feldspars are less than 1%. Perlite with quartz above this level has megascopic feldspar concentrations >3%, typically in the 5-20% range.

Jan 1, 1991

By W. L. Han, Y. D. Zhang, X. C. Li

Meta-systhetic technique for large systems engineering has been placed on the agenda. The meta-systhetic A1 approach should involve the integration of digital and knowledge info, from qualitative to quantitative analysis, etc. Some algorithms of meta-systhetic technique such as ANN-ES and GA-ANN are introduced. A case study follows - mining conditions evaluation by meta-synthetic A1 methods, including: setting up the structure of evaluation indexes system, deciding their grade of membership by ANN-ES algorithm; determining the weight values of evaluation factors by GA-ANN algorithm; and developing the integrated evaluation model.

Jan 1, 2002

By T. Weimer

Gasification of carbonaceous energy carriers with simultaneousCO2 removal is a new and interesting alternative e.g. ZECA [1],HyPr-Ring [2], AER [3]. In the ZECA process lime supported Hydrogen generation from Methane is a basic process unit and the Hypr-RING process investigates Hydrogen generation from hard coal with addition of lime. Here the main objective is a further development of the AER process. High energetic efficiencies for gasification in the range of 90 % can be achieved if the humidity of the energy carrier is already sufficient for steam reforming reaction. The aim of the overall process is upgrading coals and biomass yielding into three valuable products: • A fuel gas ready for power generation • A CO2gas stream containing >95%, ready for transportation to disposal or chemical fixation • A pre-calcined feed for cement clinkering consisting ofCaO and coal ash Thus power generation and gasification are independent. A promising industrial application is the combination of gasification and cement production. Then only one additional reactor is required and the precalcination mass flows have to be increased.

Jan 1, 2004

By [Miroslaw] M. Hajdasinski

The Payback Period (PBP) is one of the most widely applied project evaluation criteria 'in the mineral industry. As much as this criterion is liked by practitioners, it is also criticized by academicians who seriously question its validity. Inspired by this criticism, the author of this paper examines the classical definition of the PBP criterion, and formulates a new one designed for both investment and borrowing projects. It is demonstrated that the PBP, in its revised version, is free from all the shortcommings of the old one, and is fully compatible with the Net Present Value (NPV) criterion, as well as with all the other NPV compatible project evaluation criteria. Since the traditional approach to the comparison of mutually exclusive projects (MEP1s) by means of the PBP criterion has been incorrect, the paper also outlines the correct approach to this problem. Finally, owing to the fact that the PBP depends on the assumed interest rate, and using a specially developed computer program, the PBP is graphically presented, in six numerical examples, as a function of the interest rate.

Jan 1, 1989

By R. Pakalnis

A comprehensive project has been completed at the University of British Columbia that focused on the development of a commercially competitive composite cable bolt. Laboratory evaluation consisted of pull tests, preliminary shear tests, grout column testing and scanning electron microscope evaluation of the composite cable bolt. Field implementation at five underground mines throughout Canada were completed for technical and overall performance evaluation of the new product. The project began in 1989 under the sponsorship of HDRK Ltd., a consortium of mining companies including Inco, Noranda and Falconbridge Ltd. The objective was to develop a cuttable cable bolt that would serve as support for a continuous miner within a hardrock environment (Mah, 1994). The bolt was required to be cuttable by a continuous roadheader without adverse effects to equipment, personnel and the milling process. From the beginning, the focus was to employ existing cable bolt installation technology (Goris et al., 1994) whereby the cable bolts are grouted within a 4.8-cm-diam (1.08-in.diam) or larger employing a portland cement grout having a water:cement ratio between 0.35:1 to 0.4:1.

Jan 1, 1994

By John S. Livermore

I feel very privileged to be added to the distinguished group that has received this award since the first recipient, Reno Sales, received it in 1954. If my research is correct, the last geologist to be honored was Bill Callahan in 1982. Perhaps the Awards Committee decided it was about time to select a geologist, and I became the beneficiary. Regarding the discovery of the Carlin ore body, it was the culmination of several studies - one going back as far as 1939 when a US Bureau of Mines engineer named W.O. Vanderberg recognized an unusual type of gold mineralization in sediments in northern Nevada. What was unusual was the fact that the gold was so fine that it would not concentrate in a pan. This, plus the study of the Roberts Mountain thrust by Ralph Roberts (1960) and conversations with Harry Bishop, manager of the Gold Acres Mine, pointed Alan Coope and me in the direction of the Lynn Window and, eventually, the Carlin discovery. There has been a great deal written about this discovery. I thought it would be interesting to discuss the evolution of Carlin gold exploration in Nevada since this time and to discuss the changes in perception of this unique type of mineralization. The method used by Coope and me in following up on Roberts' work was to map geologically the Roberts Mountain thrust and conduct geochemical sampling of favorable outcrops and float. Coope was highly experienced in geochemical exploration, as he had graduated from the Royal School of Mines in London, studying under John S. Webb, one of the pioneers of geochemistry as applied to mineral exploration. We first considered using pathfinder elements, but finally concentrated on gold analyses alone, even though the sensitivity of fire assays used at that time was only about one-half part per million. According to the spatial relationship of the mineralization to the Roberts Mountain thrust, as pointed out by Roberts (1960), we were looking for mineralization within the thrust itself. Our models were the known Gold Acres and Getchell mines, which contained reserves on the order of 0.9 to 1.8 mt (1 to 2 million st). These were not of substantial size, but I had hoped we might find more than one of these tributary to a mill that would justify an operation for our employer, Newmont Mining Corp. What we ended up with was the type of deposit we were looking for - an open pit deposit of micron gold, which the old timers had missed because the gold was not capable of being panned. But never in our wildest dreams did we think there was a chance of finding a body containing 10 mt (11 million st) of ore at 0.30 oz/st (10.3 g/t).The deposit was not in the thrust proper but was found in a favorable horizon of Roberts Mountain siltstone that was below the thrust. This is the first example of how a model should not be followed blindly. Newmont was successful in keeping this discovery quiet for some time. After a considerable amount of drilling, a rumor circulated that they had discovered a large low-grade ore body of around 1.7 to 2.1 g/t (0.05 to 0.06 oz/st), which of course would not have been economic with gold at $1.13/g ($35/oz), which was the fixed price at that time. The company, for obvious reasons, did not discourage the rumor. When, however, the true results came out there was a lot of feverish activity. Because of this new type of so-called "invisible gold," which could have been missed by the old timers, the thought was that other deposits would be discovered very soon. The Carlin and other smaller deposits, including Bootstrap, Blue Star and Gold Quarry, were in windows where the lower plate of the Roberts Mountain formation (below the thrust) had been exposed by erosion. This then became the new

Jan 1, 1997

By William E. Cobb

15.1 INTRODUCTION The mine development process, as discussed in Chapter 2, is a series of data gathering and analysis steps. As the mine development process proceeds, information about the geology, mineability, and metallurgy of a particular deposit is continually generated, along with environmental information regarding project permitting status. As data are obtained, checkpoint evaluations are typically conducted to determine the economic viability of the particular deposit. Although the project evaluation process was discussed at length in Chapter 2, a brief review of the process is presented here to "set the stage" for the discussion on economic analysis of heap leach projects. Figure 15.1 (MacKenzie, 1980) presents an overview of the sequential process of mine development. Once the deposit is discovered or acquired, an initial delineation program can be undertaken to expand the project's geologic, mining, and metallurgical data base. At the end of this initial program, the direction of the project is evaluated. The company can either abandon the project, postpone it, develop and mine it, or gather additional data in hopes of improving the project's economic viability. If the company continues gathering data, then another decision point and evaluation will be required. This process may continue until the company either decides to postpone the project or develop and mine it. A project may be postponed indefinitely, typically in hopes of improved metals prices. Certain holding costs, such as land or royalty payments, may be associated with postponement. In general, once a company goes through two evaluations, the project is less likely to be abandoned. For this discussion, it is assumed that the company will undertake initial, second, and third delineation programs to gather sufficient geologic, mining, metallurgical , and environmental data to justify a positive production decision from the second or third economic evaluation. The objectives of the first delineation program will be to confirm and expand upon the available information about the deposit. During the second delineation program, development funds should be directed toward identifying the critical project items (i .e., ore reserves, mineralogy, mineable grade, metallurgical recovery, etc.) that must be resolved before making the production decision. This second economic evaluation can be used to determine which metallurgical concept will be applied to the project: heap leach or a traditional agitation-type leach plant. If the proper work has solved key project concerns in the second program, a production decision may be made from that evaluation.

Jan 1, 1988

By Ernest E. Thurlow

Introduction Today, more than 50% of rail-carried commodities are mineral industry related, with coal being the most important single commodity moved by rail. In 1980, coal accounted for more than 5.7 million of the total 22.6 million carloads moved by rail. Metallic ores were third behind grain, with more than 1.4 million carloads. Crushed stone, gravel, sand, and other non-metallic minerals totaled almost 2.3 million carloads. Chemicals and allied products, including fertilizer and coke, added another 1.7 million cars, with petroleum and petroleum products totaling 300,000 carloads. Coal Several things happened in the 1970s that gave rise to increased consumption of coal-particularly western coal-and to its dominant position among rail-carried commodities. First, the Clean Air Act of 1970 required generating plants to make significant reductions in sulfur dioxide emissions. To comply, utilities could either invest in scrubbers or switch to low-sulfur western coal. Many opted for the latter. By 1972, increasing demands by the utility companies halted what had been a 25-year decline in national coal consumption. Second, the Arab Oil Embargo of 1973 put an end to cheap oil and gas, limiting their future as fuels for electric generating purposes and increasing the potential for coal. Third, in 1977, President Carter announced an energy program with coal as its cornerstone, calling for an annual two-thirds increase in national coal production by 1985. He also called for conversion to coal by utilities and large industrial users. Finally, he proposed a 10-year, $10 billion program to encourage domestic coal production and stimulate development of export markets. Coal bounded into world prominence. Foreign demand for steam and metallurgical coal increased tremendously, while US demand for western coal also shot up. This meant greater demands on the transportation sectors that traditionally carried coal to market. Many railroads began programs to serve the coal industry. One example is Burlington Northern's commitment to handle increased western coal tonnages. The company spent more than $1 billion in recent years to develop a system capable of moving more than 91 Mt (100 million st) of coal each year. Other leaders in this renewal were Norfolk and Western, Union Pacific, Santa Fe, and Southern Pacific railways. The importance of the rapid growth of coal traffic to the railroads is shown in the accompanying table, which gives percentages of total tonnages hauled and revenues attributed to coal. With coal providing the railroad industry with a substantial share of its revenues, there is keen competition among the rail companies themselves and among railroads and other transportation sectors for coal haulage. But there is also cooperation when more than one railroad is involved in delivering the coal from mine to market or when a combination of transportation modes is more economical. The latter is represented by Conrail's interest in working with the port authorities of New York and New Jersey to establish a new coal port that would serve not only export markets, but also utilities and industries in the northeast. Iron Ore Next to coal, iron ore (taconite) is the most important single mineral commodity handled by railroads. In Minnesota, where most iron ore is produced, rail transportation is primarily by Burlington Northern and the Duluth, Missabe, & Iron Range Railway Co. (DM&IR). The DM&IR, owned by US Steel, serves several producers on the Mesabi Iron Range. Two of the larger producers, Erie Mining Co. and Reserve Mining Co., also own railroads that operate between the mines and the ports of Silver Bay and Taconite Harbor on Lake Superior. Several iron mines and taconite plants in Michigan are served by the Chicago and Northwestern, and the Soo Line. Total 1981 shipments of taconite and iron ore are estimated at 55.9 Mt (55 million It), compared with about 61 Mt (60 million It) in 1979 the most ever shipped in one year. Still, with annual production capacity of the eight Mesabi Range

Jan 10, 1982

By M. Churchill, V. R. Degner

Over the past two decades, declining ore body grades and increased operating and construction costs have provided an incentive for the development of progressively larger flotation machines. As a result, the 1.7-2.8 m3 (60-100 cu ft) flotation machine of the 1950's and 1960's is being rapidly replaced by large volume machines. The result has been improved flotation machine specific capacity (tph processed per sq ft of floor space); specific power (hp per tph processed); and process control simplicity. The recent development and satisfactory plant evaluation of the 28 m3 (1000 cu ft) flotation machine allows economic and operating advantages in high tonnage mill applications. Some principles of mechanically induced air flotation and the development of the large 28.3 m3 (1000 cu ft) flotation machine are reviewed here. Performance evaluation in beneficiating metalliferous ores-copper, zinc, and iron-is also given and recently completed plant results provided. Mining lower grade ore bodies results in the need to process increased tonnage in the concentrator. This greater tonnage requires more individual flotation machines, unless individual machine capacity, or cell volume, is increased. As the ore processing rate of the concentrator increases, the benefits of progressively larger individual cells in the flotation section become more significant. The accompanying figure illustrates the advantages of a larger flotation machine. In the figure, the number of machines in the rougher-scavenger section is related to the plant tonnage for three sizes of flotation machine: 8.5 m3 (300 cu ft), 14.2 m3 (500 cu ft), 28.3 m3 (1000 cu ft). The 28.3 m3 (1000 cu ft) flotation machine results in 95 fewer machines, compared to the 8.5 m3 (300 cu ft) machine at 45.4 kt/d (50,000 stpd) feed. The flotation cell reduction is, of course, doubled at a plant production rate of 90.7 kt/d (100,000 stpd). Using fewer flotation machines saves floor space. The 14.2 m3 (500 cu ft) and the 28.3 m3 (1000 cu ft) machines result in a floor area reduction, relative to the 8.5 (300 cu ft) machine requirements, of 134.7 and 418.1 m2 (1450 and 4500 sq ft), respectively, for the 45.4 kt/d (50,000 stpd) rate and 269.4 and 836.1 m2 (2900 and 9000 sq ft), respectively, for the 90.7 kt/d (100,000 stpd) rate. In addition, flotation practice has shown that the "specific power intensity"-power per unit cell volume-is less for increased cell size. This results in a power draw reduction, for the rougher-scavenger circuit, of between 552 and 686 kW (740 and 920 hp) for the 14.2 and 28.3 m3 (500 and 1000 cu ft) machines, respectively, when processing 90.7 kt/d (100,000 stpd). Fewer cells improve machine control and simplify maintenance needs while reducing floor space and power requirements. These are tangible incentives for the development of large flotation machines for high tonnage applications. Flotation Principles The accompanying figure shows how key hydrodynamic regions influence the performance of a mechanically induced air flotation machine. Air is induced into the fluid from the top of the cell, due to the mechanical action of a rotating impeller. The impeller circulates the liquid, or pulp, from the bottom of the cell. The result of these dual flow paths is the mixing of the two fluids and one solid phase in the highly agitated region where physical contact between the air bubbles, and the solid particles to be floated, is accomplished. The particle to be floated is assumed to have a properly prepared hydrophobic surface prior to flotation. Upon leaving the three-phase mixing region, the "floatable particle-air bubble matrix" and

Jan 7, 1982

By M. A. Alan

The Bellavista Gold Deposit lies 75 Kms north west of San Jose, the capital of Costa Rica, Central America and 3 Kms north east of Miramar, in the Province of Puntarenas. The total road distance from San Jose to the deposit is 120 Kms all paved road except for a 2.5 Km graded, gravel road on the property (Figure 1). Infrastructure services in the Miramar-Puntarenas area are well developed with electrical power distribution, a modern port facility and community services being available. The deposit lies on the south west flank of the Tilaran Mountain Range between an elevation of 550 and 800 meters above sea level. The local topography is steep, originally covered with pre-montaine, tropical wet forest vegetation which has been largely destroyed due to clearing for cattle grazing. The annual rainfall is approximately 2,950 mms, 90% of which occurs between May and October.

Jan 1, 1992

By D. K. Grubbs

Anorthosite is an abundant, domestic source of alumina with reserves in individual deposits ranging from a few billion to hundreds of billions of tons. While anorthosite contains less alumina than does kaolinite, its CaO and Na20 contents are significantly higher (Figure 1). Alumina can be produced from anorthosite by alkaline, soda-lime sinter or acid processes. CaO and Na20 are advantageous because they are reactants consumed in alkaline processes. Acid processes require high calcium plagioclase feldspars (bytownite-anorthite) to obtain high alumina extraction because the lower calcium plagioclase feldspars (andesine-labradorite) are not as readily dissolved during digestion. The layered Raggedy Mountain Gabbro group in the Wichita complex in southwest Oklahoma is a high calcium anorthosite that could be processed by acid, sinter, or alkaline methods. Chemical grade limestone in the Arbuckle Group is located within 45 km of the anorthosite (Figure 2).

Jan 1, 1980

By J. R. England, W. J. Taylor

The Sudbury Basin is the scene of the mining operations of the Ontario Division of the International Nickel Company of Canada, Limited. Around the rim of the geological formation and within thirty miles of the City of Sudbury are located twelve operating mines and one open pit operated by the Company. The City, with a metropolitan population of some 100,000 lies 240 miles Northwest of Toronto. In addition, there is one mine in Northwestern Ontario, at Shebandowan, 700 miles Northwest of Sudbury. In 1973 these mines produced 16.5 million short tons of ore of which 14.9 million tons were from underground and the balance from open pit operations. Mining methods include blasthole, sublevel caving, induced caving, shrinkage, cut-and-fill and undercut-and-fill. Raise boring commenced at Inco in 1964 and is now applied at all mines in the Sudbury District (Figure 1). [ ]

Jan 1, 1974

By Catherine T. Aimone

A computerized cost model has been developed to simulate the technical and economic effects of strip mine blasting in the vicinity of structures. Current surface mining regulations restrict the allowable level of production blasting as a function of this distance. Blast design modifications,' therefore must be employed when blasting in the vicinity of homes to ensure compliance with federal and state regulations specifying limits to the seismic effects generated from a blast. The blasting level allowed. is computed by the charge weight of explosives per delay from the following scaled distance formula: [ ] where W is the charge weight per delay, in kilograms (pounds), D is the distance factor corresponding to the regulatory limit of peak particle velocity to which a structure may be subjected to. Current regulations specify 2.54 cm (1.0 in.) per second corresponding to a SD factor of 27 (60) (Federal Register, 1977).

Jan 1, 1982