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By M. C. Williams

As the flaws in the population balance model (PBM) comminution model are examined more deeply, further errors and problems were discovered. The Levenberg-Marquardt algorithm for systems of constrained non-linear equations was used to solve the dynamic PBM grinding equations to obtain the grinding selection and breakage rate functions. The fact that the PBM model equation Inverse Problem is degenerate or underspecified is demonstrated. Multiple solutions to the same PBM equations are provided. It is shown that there is no unique solution to the Inverse Problem unless additional constraints are provided or assumptions are made such as the Arbiter-Bhrany normalization assumption. The severity of the non-uniqueness problem for dynamic grinding is demonstrated. Each solution to a dynamic PBM, while giving the same prediction for a given grinding time interval, gives different solutions or predictions for mill composition for other grinding times. Actual experimental grinding data was assessed to determine the functionality of mill selection and breakage functions.

Jan 1, 1993

By Louis M. Perlman

Quantitative methods are, by now, a standard tool of the mining industry, and are commonly used by Research Departments in their evaluation of production methods and schedules, and their associated costs. Indeed, much sophisticated computer work has been devoted to such evaluation of controllable costs and capital requirements. These data are an important input into the project evaluation formula, which is probably the most important single calculation per formed by a mining company, since the result decides whether a particular project is viable. It is instructive to summarize the broad principles of project evaluation, since they are crucial to the remaining sections of this paper. PROJECT EVALUATION The most widely used method of appraising projects is known as Discounted Cash Flow (DCF) method. Two main variants are used; they are known as the 'not present value' (NPV) approach and the 'internal rate of return' (IRR) approach respectively. The difference between the two is that the former takes the firm's interest rate as given and uses this knowledge to calculate the present value of the project; whereas the latter calculates the highest interest rate the project could tolerate and still just breaks even. The technique is more simply discussed in terms of the first method (NPV).

Jan 1, 1972

By W. E. Cobb

The financial implications of environmental liabilities are becoming staggering, particularly for mining companies. The Environmental Protection Agency's (EPA) Record of Decision (ROD) list for Superfund mining sites has some pretty hefty financial commitments, such as the $10 million operable unit remedy for the Yak Tunnel at California Gulch (in Colorado) or the $40 to 60 million remediation at Bunker Hill (in Idaho). These costs are driven by the large volume and areal extent associated with historical waste management practices at mining sites. (It's difficult to have a low-cost remedy for a 20-square-mile site.) Unfortunately, there are other ways of generating environmental liabilities besides Superfund, such as non-compliance with Clean Air Act provisions, stormwater permits, or National Pollutant Discharge Elimination System (NPDES) permits. In the last 2 years, EPA has increased enforcement in its regulatory programs, which has resulted in increased fines and criminal actions. Leaders in other industries (primarily the chemical and manufacturing industries) are viewing environmental liabilities as a strong motivator to select engineering approaches carefully based on technical, legal, economic, and philosophical perspectives. Industry interest in waste minimization programs comes from the concept that it is economically advantageous not to create waste in the first place. Waste minimization programs typically balance increased front-end capital investment with the minimization of potential long-term environmental liabilities as a way to achieve the lowest total-or life-cycle-cost. A side benefit of waste minimization programs is that they tend to improve overall regulatory compliance. Waste management practices are also becoming philosophical, as evidenced by a May 11, 1992, Business Week article: Companies that incorporate innovative thinking on sustainable development will do more than clean up or prevent their own pollution. They'll make and distribute a product more efficiently than ever, worry about its lifelong environmental impact, plan for recycling, and get their suppliers on the bandwagon. This type of approach will require a new mind-set, new tools, and adjustments throughout the organization. A key aspect of waste minimization or life-cycle waste management programs is the incorporation of environmental costs into economic analyses that compare various waste management alternatives. However, the incorporation of environmental costs into an economic analysis can be more difficult than initially thought. As noted above, new tools-or even a new toolbag-are needed, such as new accounting methods that track and assign the true lifetime environmental costs of a particular product. One piece of the new toolbag is life-cycle cost analysis, which is discussed in this paper. To simplify the discussion, this paper looks at the total costs associated with a given mining site. The concepts presented in this paper, however, can be applied to any mine waste management decision. The ultimate extension of life-cycle costing, as presented in the Business Week article, is to include the potential environmental costs throughout the life of a metal. At this point, I am perplexed on why, let alone how, to include the potential downstream environmental costs (i.e., the costs associated with smelting, manufacturing, use, and recycle or disposal) throughout the life cycle of mined copper, lead, or zinc.

Jan 1, 1992

By Jr. Garnar

Heavy mineral mining has been a relatively small but important Florida industry for over sixty years. Geology of the Florida heavy mineral deposits is similar. Each formed along active coastlines after which the titanium minerals were upgraded in TiO2 by post depositional oxidation and leaching of the iron. There are four heavy mineral plants currently Operating in Florida. Ore is mined by dredges and the heavy minerals concentrated by gravity separation. The heavy mineral concentrates are further processed with high tension and electromagnetic separators to Produce titanium mineral concentrates for TiO2 pigment manufacturing plants. Zircon sand is produced as a co-product at all of the Florida plants. Staurolite is produced by Du Pont and Titanium Enterprises. Du Pont also markets a kyanite-sillimanite product. (Monazite is produced by Humphreys and Titanium Enterprises). Reclamation of mined-out land is an important part of heavy mineral mining. At the Du Pont plants soil is removed ahead of the dredge and placed over the quartz sand tailings. Grass is planted after fertilizing. A year later the land is fertilized again and pine trees planted. Most of the heavy mineral deposits now being mined will be nearly exhausted by the end of the century. New deposits to be mined in the 21st century will probably be smaller and lower grade than those now being mined. Advances in mineral processing technology will have to be made to allow these lower grade deposits to be mined economically.

Jan 1, 1978

By V. R. Bovino

In the early 80's, the cover of a major weekly magazine proclaimed the "Death of Mining." A few years ago, mining conventions, similar to this, around the country sported the theme, "The Survival of Mining." Today, the SME announces that "Mining is Alive." Being part of an industry that is simply alive is not very exciting. We can do better! Our challenge must be to flourish, blossom, maximize our potential and expand our horizons. The pace of rejuvenating this industry is still woefully inadequate. The new generation of mining industry leaders recognizes the urgent need for bold operational changes?changes in the way we deal with our employees? changes in the way we achieve productivity? and changes in the way we reward our employees for productivity.

Jan 1, 1991

By Larry D. Patts

Section 317(e) of the Federal Coal Mine Health & Safety Act of 1969 directed the Secretary of the Interior to prepare standards under which all working places in a mine shall be illuminated by permissible' lighting while persons are working in such places. Section 317(e) further provides that such Working places shall be illuminated within 18 months after such standards are promulgated. In accordance with this section of the Act, there was published in the Federal Register for December 31,1970 a notice of proposed ru1emaking which prescribed the illumination to be provided in the working p1 aces of underground coal mines. In 1ight of written comments, suggestions, and objections to this proposed ru1emaking, the proposed standards were with-drawn and reproposed in the Federal Register for Wednesday, October 27, 1971. In light of further comments, suggestions, and objections, a public hearing was held on April 4, 1974 and standards were again reproposed and published in the Federal Register for April 1, 1976. Promulgation of the final lighting standards took place on October 1, 1976 which means that the underground coal mining industry must comply with face illumination requirements by April 1, 1978. As mentioned previously, the first proposed ru1emaking for illumination of underground coal mines was published in the Federal Register on October 27, 1971. In early 1972, Consolidation Coal Company (Consol) and the United States Bureau of Mines agreed to a cooperative study of underground face illumination; Conso1 felt that expertise in this field would become increasingly important. Conso1's initial efforts in illumination were aimed at investigati.ng practical lighting systems for underground face equipment. We were concerned with installing unobtrusive lights which provided sufficient face illumination for safety, but at the same time were readily maintainable, electrically reliable, and physically sheltered from damage.

Jan 1, 1977

By J. C. Bradbury

The Illinois State Geological Survey's program in industrial minerals is twofold-the gathering of information on mineral raw materials and the generation of data on the use of these materials. The first function is carried out by the Industrial Minerals Section and the Clay Resources and Clay Mineral Technology Section of the Geological Group, and the second is the responsibility of the Chemical Engineering Section of the Chemical Group. Gathering in formation on raw materials includes both mapping of resources and fundamental geological research. Recent and current research projects include studies relating lithologies of limestones to their physical properties, investigation of sulfur dioxide reactivity of various types of limestone, lithostratigraphic studies of limestones of Mississippian age, investigations of heavy minerals in Cretaceous, Tertiary, and Pleistocene sands, studies of the environments of clay deposition, electron microscope studies of clays and limestones, and investigation of long-term expansion in ceramic products. A relatively recent development that relates more to dissemination of information than to research is environmental geology. This affects the Survey's industrial minerals program chiefly by stimulating the study of rock and mineral resources in metropolitan areas and reporting the results for the land- use planner as well as the engineer or mineral producer. The Survey's program of research on the use of industrial minerals was expanded and diversified in 1966. Incorporating a minerals beneficiation lab, the program is designed to develop new uses for existing mineral resources and to assist producers in implementing these ideas: Projects of the minerals engineering program have included the separation of a feldspar concentrate from certain glacial outwash and river sands, recovery of kaolinite from the waste from silica sand operations, development of the use of an Illinois clay as a binder for pellets, and investigations into the use of fly ash and fluorspar mine tailings.

Jan 1, 1970

By Harold Wagner, Prakash Donde, Larry H. Heflin

INTRODUCTION The Washington Metropolitan Area Transit Authority is responsible for the planned 166 kilometer (103 mile) Metro rapid rail transit system in Washington, D.C. Some 117 kilometers (72.8 miles) of this system is in operation and contains 30.6 route-kilometers (19 miles) of rock tunneling. To complete the planned system an additional 1.6 kilometers (1.0 miles) of single track tunnels in rock are planned and additional contracts will consist of 4 kilometers (2.5 miles) of twin tunnel, resulting in 8 additional linear kilometers (5 miles) of single track tunnel contracts yet to be offered in soft ground. Three recent contracts in soft ground included the New Austrian Tunneling Method (NATM), along with conventional tunneling, as a bid option. Section E5a, Fort Totten Station and Tunnels, was the only one of the three to be constructed using the NATM option. This is the first application of the New Austrian Tunneling Method in soft ground in the United States. This paper will concentrate on the Fort Totten Station chamber NATM design, construction, and the instrumentation readings and evaluations which lead to an engineering back analysis which allowed a refinement of the bid design, resulting in a faster, more efficient construction. Design of the Fort Totten Station and Lines was done by Sheladia Associates. The design team included Greiner Engineering and Jenny Engineering with Mayreder-Consult of Austria, who was responsible for NATM design and NATM construction consultation.

Jan 1, 1991

The Chinese city of Shanghai is one of the fastest growing in the world. To keep up with the growth, two tunnels, three-lanes each, are being built beneath the Yangtze River to connect Shanghai with the Changxing River Island. To complete such a large project, Herrenknecht Tunneling Systems was brought in to construct the largest tunnel boring machine (TBM) in the world. The first Herrenknecht S-317 Mixshield has a diameter of 15.43 m (50.62 ft). It was built to construct one of the two 7.2-km (4.5-mile) tunnels. The tunnels are part of the Changjiang Under River Tunnel Project and will be at depths of up to 65 m (213 ft) beneath the Yangtze River in Shanghai-Pudong. These two tunnels are to be opened to traffic in April 2010, in time for Shanghai to host the World Expo. More than 20 million people live in the Shanghai area. The area itself has been growing at an extremely rapid pace for more than a decade and is in need of more space. The search extended beyond the natural limits of the Yangtze River Delta. As part of its incredible growth, 500 new vehicles are registered every day. The new tunnels will connect the Changxing River Island, with a population of approximately 600,000 people to the road traffic network. A bridge construction will also provide a traffic link between Changxing Island and the large island of Chongming.

Jan 1, 2007

By L. E. Mercando

The proposed Flambeau Mining Project is based on a high grade copper deposit located approximately one mile southwest of Ladysmith, Wisconsin. The project involves only the mining, crushing, and shipping of ore to facilities outside of Wisconsin for processing. The Wisconsin environmental regulations include provisions for identifying wetlands, the requirements for minimizing the disturbance of wetlands, and the need to establish new wet-lands to replace any wetlands which have to be disturbed.

Jan 1, 1991

By Wolfram Schnabel

Recently Lurgi has succesfully commissioned Peru's first direct reduction rotary kiln at SIDERPERU?s Chimbote works. The order included comprehensive engineering services and supply of special equipment to modify three existing cement kilns according to the SL/RN process. The kilns were cut to 62m length and installed with a slope of 2.5%. A new heating system, including shell burners, was supplied and inlet and outlet ends of the kilns completely renewed. Figure 1 shows the kilns after modification.

Jan 1, 1981

By Ross Goodman, Jean-Luc des Rivières

The Ohio River Tunnel Project encountered multiple unexpected geotechnical challenges which, continuing to develop over time, hampered excavation completion and impacted the cast-in-place final lining technique and work execution sequence for the entire project. The continued degradation of the excavated hard rock tunnel conditions led to a unique, dynamic, geologic setting that forced the project to innovate new and adaptable measures allowing for a conventional cast-in-place liner to be completed in a safe and timely manner and minimize delay.

Jun 13, 2023

By David R. Hargis

Large-scale groundwater withdrawals are necessary to depressurize a confined aquifer system allowing the dry open-pit mining of the overlying phosphate ore. The extent of the existing and planned groundwater development led to the establishment by the State of North Carolina of Capacity Use Area No. l. Groundwater use in the Capacity Use Area is regulated by a permitting system. A two-dimensional finite-difference ground- water flow model was developed for North Carolina Phosphate Corporation. The aim of the model is to aid the Corporation in matters relating to permitting by serving as a predictive tool. The model can be used to project regional water level impacts resulting from various scenarios of depressurization pumping.

Jan 1, 1983

By J. D. Allen

The Concord Mine Coal Preparation Plant of United States Steel Corporation, located near Bessemer, Alabama, began operations in June, 1950. The basic cleaning circuit consisted of a Chance Cone for cleaning the 2-inch x 3/8-inch fraction and concentrating tables for cleaning the minus 3/8-inch coal fraction. Dewatering of the final product was accomplished with 35-mesh vibrating screens. However, because Concord coal is very friable (Figure 1), 85 per cent passing three mesh and 25 per cent passing 28 mesh, there was a considerable amount of fines passing through the dewatering screens. To recover these fines, the dewatering screen effluent was sent to two 70-foot diameter hydro-separators with the underflow returning to the dewatering screens and the overflow going to a 175-foot diameter thickener for water clarification, (Figure 2). As might be expected, there was a considerable amount of recirculation of the minus 35-mesh coal in this system. This degraded the coal and led to higher moistures. It also resulted in a fines bleed-off of plant water and thickener underflow to a fine-coal settling pond. In 1961, vacuum filters were installed to supplement the screens and to recover the fine coal lost in the bleed-off. The above system resulted in a product moisture of about 20 per cent. Further reduction to approximately 11 per cent was accomplished by drainage from railroad cars during transit to the coke plant. Control of the moisture at unloading was poor because of variations in operating levels and railroad car availability, but since the Concord coal constituted a smaller percentage of the coal previously used at the coke plant, the high moisture and fluctuations did not seriously hamper coking operations.

Jan 1, 1966

By William A. Wallace

Common mineral resources (sand, gravel, crushed stone, etc.), which are so necessary for the construction of metropolitan areas, are rapidly being depleted or otherwise rendered unavailable in the very areas that need them most. However, the problem of planning for these resources involves a number of independent and dependent variables that must first be defined and related. Finally, a dollar value must be assigned where possible. Complex interrelationships between the variables and their dependence on outside factors has made mathematical "solution" of the problem of planning for non-renewable mineral resources difficult at the present time. Therefore, the use of computer simulation is suggested as a means by which this complex problem can be investigated. The purpose of this paper is to report on a continuing research program whose objectives are: (1) to delineate the factors involved in planning for the utilization of common mineral resources in urban-suburban environs; (2) to construct a planning model for these materials amenable to computer analysis, (3) evaluate the model by using test cases, and (4) perform a sensitivity analysis to determine the initial parameters in future planning for these materials.

Jan 1, 1968

By P. J. G. du Toi

Anaconda's experience with percussion longhole drilling in Butte, Montana, has consisted of six phases: 1. Drilling horizontal blast holes in stopes with push feeds. 2. Ring and parallel blast hole drilling in longhole stopes with bar mounted as well as skid jumbo mounted longhole drifters. 3. Ring and parallel drilling in raise climber shrinkage stoping using special raise climber drilling decks designed and built in Butte, Montana. 4. Parallel longhole drilling in horizontal cut and fill stopes with monorail jumbo. 5. Drilling water drain holes between mine levels. 6. Drilling leach holes through caved zones into old stope workings for leaching purposes. 7. Sample hole drilling.

Jan 1, 1970

By C. W. Schultz

The Alabama tar sands of the Hartselle Sandstone formation present a more difficult problem in primary extraction than do the Athabasca tar sands. In contrast to the Athabasca tar sands, the Alabama tar sands are "oil wetted" and the contained tar, or bitumen, is of much higher viscosity. A physical beneficiation scheme was developed in which clean sand from an external source was used as a scrubbing medium. High intensity scrubbing liberated the tars which are readily recovered by froth flotation. Locked cycle tests have shown that, after the use of an initial ration of clean sand, the system produced enough new clean sand to be self sustaining.

Jan 1, 1992

By Jean-Michel M. Rendu

Increasingly, geologists use geostatistical methods to evaluate drilling programs. The complexity of the methods varies with the nature of the available sample information, the objective of the statistical analysis and the geologist's experience. Occasionally, estimating the average sample grade is all that is required. In other instances a semivariogram calculation may be considered. If sufficient data is available, the geologist may wish to estimate blocks or panels of complex shape, using the kriging method of evaluation. Historically, the use of geostatistics by geologists has been limited by a number of factors, most significant being the difficulty in accessing and using computer programs needed to complete the necessary studies. Geologists are often working in remote areas from which electronic communication is unreliable, if not impossible. Even when access to computer programs is technically possible, the costs incurred in accessing and using these programs are often considered prohibitive. In many instances using the programs requires an understanding of computer systems far beyond that which a field geologist can justifiably be interested in acquiring and maintaining.

Jan 1, 1984

By Randall D. Peterson

Strip mining with draglines and other surface equipment has traditionally been the method of choice for mining shallow deposits. This is particularly true for soft deposits that require little or no blasting. High rates of productivity and low operating costs have set this standard. However, these methods can be improved. Strip mining methods are batch processes and difficult to accommodate in processing. Moreover, they are encumbered with overburden removal, reclamation expense, and human inefficiencies. This paper describes the invention of a novel shallow earth mining technique called the Softwall Mining Method. Softwall Mining is an adaptation of longwall mining for loose earth conditions. The method was specifically invented for recovering phosphatic clay ore from beds in North Central Florida, but is likely to be suitable for a number of other minerals as well. Potential deposits for which the method may be well suited include placers, disseminated deposits in soft host rocks, bauxite, soft coals and lignite deposits, and other deposits where overburden will subside readily and where the ore can be hydraulically broken and slurried. Unit operating cost advantages are expected over the current dragline systems used. The Softwall mining advantages are its high rates of productivity, control and automation of the mining process, reduction of dilution and waste, and elimination of the majority of stripping and reclamation.

Jan 1, 1998

By Terry B. Linde, William M. Dowall

The recently completed In-Pit Crushing and Conveying Project at Phelps Dodge's Morenci Mine is rated among the world's leading materials handling projects. The operation involves the crushing and transport of more than 109,000 tonnes per day of copper ore, utilizing regenerative conveyors capable of providing over 5.5 megawatts (7,000 hp) of equivalent electrical energy. This paper describes the key aspects of the project and includes: Original project objectives; System design criteria; System description; Optimization studies; Major design features; Equipment description; and System commissioning.

Jan 1, 1993