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By M. J. Laurila

The concentration of low grade iron ores to pellets or sinter fines suitable for blast furnace feed or direct reduction is highly energy intensive and costly in terns of both size reduction and separatory processes. Large equipment with high throughputs are required to make the fine grinds and multi-stage separations economical. Control of these circuits is essential to producing a high grade product. As a result, iron ore concentrators possess some of the more sophisticated instrumentation for process control in the mineral dressing industry. These instruments must characterize flowstreams of up to 8,000 gpm where 80% of the particles are less than 50 µm. The past decade has been one where enormous strides have been made in automated control of iron ore plants. This paper reviews state-of- the-art control systems for crushing, grinding, magnetic separation, froth flotation and sizing/classifying circuits. Trends toward computerization and plant automation in response to a dismal outlook for North American steel production are also examined.

Jan 1, 1984

By L. L. Oriard

There are certain site-specific geological and physical features of a rock mass which control its behavior under the dynamic stresses induced by the action of explosives. It is essential that blasting technology be adapted specifically to those features. There does not exist a single, simple "right" way for each type of blasting operation, but rather each operation must be custom-designed for each site. When this is done, it is often possible to produce unusual but highly desirable end resglts, such as undisturbed narrow rock walls, monoliths and square benches. Although the techniques illustrated here were developed specifically for "sculpture blasting", the geomechanics principles would apply to other types of blasting control, both large-scale and small-scale. Because the techniques are designed more for the purpose of modifying the site responses which would ordinarily be expected than they are to developing new "blasting formulae?, the name "Modified Site Response Blasting" will be used.

Jan 1, 1984

By R. J. Pokora

This Bureau of Mines report is an applications manual that can be used by the nonmetallic mining industry for guidance in installing noise control materials into crushing and screening plants. These noise control modifications were installed and successfully tested at three operating quarries. This report identifies the major noise sources that can be encountered in crushing and screening plants, and discusses the applicable noise control materials and techniques that a plant operator can utilize on a retrofit basis to reduce equipment noise.

Jan 1, 1984

By James M. Griffin

Ladies and Gentlemen, There have been no less than ten major coal project financings in the last eighteen months. Each of these has been in the order of $100 million to $1 billion for the development of a coal property and its associated infrastructure. It is appropriate at this time to review the nature of these past financings. Why has there been so much activity? There are primarily two reasons. The first is due to the large number of contracts which were signed as a result of OPEC oil shocks. High projections were made for increased coal consumption particularly in world trade. This is distinct from domestic coal mine/power plant projects which often tap a government source of funds. Second is the high cost of coal development in the 1980's compared with a typical company's corporate borrowing capacity.

Jan 1, 1984

Is your company paying taxation on profits which are partly illusory?ò Are unions making wage demands based on erroneous notions of the real level of value added to your companyÆs production?ò Do you receive historic data on profit contributions by different products, or for different market areas, which you feel may be misstated?ò Do you find that cash is not always readily available to pay dividends out of reported earnings because, it is required to finance additional working capital without a real increase in the level of activity?ò Are your planning and budgeting routines hampered by the need to rely on historic financial data which bear little resemblance to what the future may hold for your company?ò Are you able to maintain your business at its optimum operating capability or do you feel each year that it becomes more and more difficult to achieve the same volumes of prdduction at the same level of return on assets employed without having to raise more capital?If your answer to any of these questions is "yes", then it is very likely that Current Cost Accounting (CCA) has something to offer you!characteristics of the mining industry and for single venture mining operations.

Jan 1, 1984

This paper is written in response to a request from the UTRC Committee on Perimeter Control Blasting. That Committee is conducting "follow-on" research on the selection of appropriate blasting designs and products for perimeter control of rock excavations. This paper will deal with the rock mechanics principles which affect the outcome of such blasting, and explain to the reader how to apply techniques which will modify the typical site response one would expect for conventional blasting methods. For convenience of reference, and to emphasize the important concept that the application of this technique is site specific, that is it must be custom-designed for each site, the technique is being called "Modified Site Response Blasting".

Jan 1, 1984

Real gross national product increased at a larger-than- expected annual rate of 8.3 percent in the first quarter of 1984, with both consumption and investment spending increasing significantly in real terms (table 1). Residential and nonresidential fixed investment increased at annual rates of 25.7 and 14.6 percent during the first quarter of 1984, and investment in nonresidential structures, which declined in 1983, also increased during the first quarter of 1984, nearly attaining its 1982 level. The annual level of personal savings increased $27.7 billion, while the personal savings rate (the ratio of personal savings to disposable income) increased to 5.8 percent during the first quarter. The increase in the personal savings rate comes as welcome news to analysts concerned over the flow of loanable funds to the private sector and the impact on interest rates in 1984 of increased private and Government demands. U.S. Minerals Industry Performance A major upswing in the performance of the metal mining sector occurred during the first quarter of 1984, with production increasing almost 11.2 percent from January to March, The recovery of the metal sector is also reflected in the performance of primary metal industry profits, which were positive during fourth quarter 1983 following seven consecutive quarterly losses (table 1). Two thousand nine hundred more metal mining production workers were employed in February 1984 than in February 1983.

Jan 1, 1984

By Peter B. Lilly

I appreciate the opportunity to tell you something about Kerr-McGee's Galatia Mine in Southern Illinois. This new underground mine was a departure for us since our previous experience had been gained in large surface mines in Wyoming. Although we were new, we did have the corporate experience in the operation of deep uranium and potash mines in New Mexico and Wyoming, and an earlier underground coal mine in Southeast Oklahoma. In arriving at our final design, we evaluated numerous concepts and finally settled on a two seam mine sharing a single shaft and slope. The mine, in turn, would be supported by a heavy media processing plant designed to optimize the yield from either seam. Further, we wished to be able to keep the two seams separate so that we could sell either seam separately or in a blend. Due to the thickness of the coal, the practical area dedicated to the mine provided forty to fifty years operations at the selected mine capacities. It was important, therefore, that our design and selection of hardware and systems provide for long life and low maintenance in order to compete in today's competitive markets.

Jan 1, 1984

By Don B. Hunter

The Bureau of Mines investigated the extraction of alumina from calcined kaolin by leaching with boiling RCI in a train of three 50-gal continuous, stirred reactors. Slurry discharged from the reactors con-tained an excessive amount of fines, which impeded solid-liquid separation. Autogenous grinding of coarse solids that accumulated in the reactors was the source of the fines. This report describes modifications to the reactors and to the operations that led to decreased fines generation and improved solid-liquid separation. Modifications to the reactors included custom-made impellers, the addition of a baffle system, a subsurface slurry discharge system, and slower rotation of the impellers. Concurrent testing of a continuous horizontal belt filter showed that the form filtration rates were increased from 350 to almost 1,000 Ib/h+ ft-2 when the modified reactors were used.

Jan 1, 1984

By Patricia Curtis Petty

Thirty years ago, the appearance of a female mining engineer, geologist or miner in a company, union or mine environment would have been unthought of, unwelcomed and violently opposed. Twenty years ago, the intellectual perception of the news that women were interested in becoming mining engineers, geologists and miners had been accepted by the industry-but no one wanted to be the first to hire one of these exotic creatures. Ten years ago, those who had been most vehemently opposed to the philosophical idea of women working in these areas were faced with competent, productive engineers, geologists and miners-who only incidentally happened to be women-and began hiring them. Historically, of course, one can always find the isolated individual who worked in these areas-the first female graduate of the Colorado School of Mines with a mining engineering degree graduated in 1903-but the concept of woman as professional engineer was very slow in arriving in the United States. The few who worked as miners generally worked in small family enterprises, such as some of the coal mines in both Eastern and Western United States. Others accompanied husbands or sons into wilderness areas searching for gold and other precious metals.

Jan 1, 1984

By Robert B. Fulton

Summary of data and estimates for 52 fluorspar properties in the following 13 foreign countries: Mexico Thailand China (PRC) Morocco Tunisia Italy Spain South Africa France United Kingdom Kenya Namibia Federal Republic of Germany Data includes deposit type, resource tonnage and grades, mining and beneficiation methods, annual production, fluorspar products and by-products, manpower requirements, capital and operating cost estimates. For operating properties, engineering and cost data have been developed for present and anticipated levels of production. Hypothetical operations have been assumed for undeveloped deposits.

Jan 1, 1984

By D. E. Ranta

Orebodies with intricate three-dimensional shapes (such as porphyry molybdenum deposits) are difficult to model using geostatistics or other computer-assisted methods. The strong trends in their spatial grade distributions occur as mathematically complex shapes and prevent the customary assumption of local stationarity that is required for accurate ore reserve estimation. "Zoned Kriging", a new method developed by AMAX, solves this problem directly by using the geologist's interpretation of the ore zones as a parameter in the kriging equations. The geological basis and methods used in the Climax ore zoning technique are reviewed and discussed relative to their application in zoned geostatistical modeling. The Zoned Kriging technique is described and demonstrated using data typical of mineral deposits.

Jan 1, 1984

By D. A. Buckingham

The Bureau of Mines evaluated potential availability of domestic nickel from 23 deposits, Evaluations included an estimation of in situ and recoverable resources, applicable mining and processing technologies, and capital and operating costs. Discounted cash flow analysis with a 15-pct rate of return was used to determine the average total cost of production of each operation, Identified in situ resources contain 9.0 million metric tons (t) of nickel; 5.5 million t is recoverable as nickel metal or ferronickel. Demonstrated in situ resources contain 8.2 million t of nickel; 4.8 million t is recoverable as nickel metal or ferronickel. No nickel is available at a total cost of production equal to the January 1983 market price of $3.24 per pound. Analyses indicate that potential annual production can only meet current consumption levels at a total cost of production of $7.60 per pound of nickel, Nickel's availability is contingent on (1) successful adaptability of nickel processing methods to domestic resources, (2) location of a smelting facility, and (3) marketability of byproducts and coproducts. Analyses were performed on the effects of byproduct and coproduct revenues, energy, labor, and transportation costs, and metallurgical recoveries on nickel's availability.

Jan 1, 1984

By Richard L. Profio

A practical analysis of the three basic elements of a mining shovel's productive capacity. Payload Speed Reliability Improved dipper fill factor is explored referring to the latest generation of wide dippers combined with higher "bank horsepower" capabilities of modern drive systems. Cycle time improvement is reviewed including overall attachment geometry and coordination of motions. A specific case study is detailed. Basic reliability of welded structures, machinery components, and electrical systems are related to operating costs. Three basic elements determine a mining shovel's long term productive capacity: 1) Average payload per cycle. 2) Average cycle time; and 3) Reliability. This paper deals with productivity gains that are possible with existing shovels as well as new equipment.

Jan 1, 1984

By David Butts

Completion of a railroad to the high Tibetan Plateau in Central China has now made it economical to exploit its mineral reserves. Lead and zinc mines are now being established. A potash plant to produce 40,000 tons per year KC1 is now in operation. Plans to produce 200,000 tons per year by 1987 are being implemented. Pilot drilling for oil and natural gas have proved up reserves. Slaughter houses are being constructed to ship yak, mutton and beef from the endless grasslands on the plateau. Research Centers in Xining and Golmud have been completed for the sole purpose of increasing technology and exploitation of the Tsaidam Basin and surrounding area.

Jan 1, 1984

By Dean S. Rogers

The conventional role of exploration, development and grade control is examined in this paper within the context of the many and varied types of gold occurrences which are found at the Dome Nine. The account endeavours to trace the development of the total ore evaluation process, from diamond drilling through the exploration and drifting stage, to the stope development and planning phase of the operation, with an emphasis on sampling techniques and assaying procedure. The concept of ore reserve calculations is developed and the practice of grade control is described. In summary, the role of the geological, the engineering and the mining department is presented in relation to the contribution each has to make in the evaluation and exploitation of ore from one of the world's classic Archean gold deposits.

Jan 1, 1984

By M. A. A. de Klaver

Due to the current cost and availability of crude oil in Brazil, Samarco Mineracao S. A., as part of its program of quality and productivity optimization and reduction of operating costs, has undertaken tests to utilize alternate energy sources for fuel oil used in its pelletizing plant at Point Ubu, Espirito Santo, Brazil. The energy program undertaken by Samarco consists of two basic steps. The first step was to reduce energy consumption, that is, to improve the thermal efficiency of the process. Secondly, a program was started to substitute the fuel oil with coal.

Jan 1, 1984

By J. D. Brown

The purpose of this paper is to inform members of the coal producing and consuming community about techniques used by The Carter Mining Company to control product quality at a large surface coal mining operation. During the early years of mining operations, coal quality received adequate attention but the Company's main emphasis was to build up its production rate and minimize mining costs. While these goals are still of prime importance, coal quality has received substantial attention in recent years. A Company guideline that no coal shipment shall exceed any contract or company-imposed coal quality specification has been successfully implemented. To implement this guideline, geology and coal quality modeling procedures were improved, in-pit drilling and blending programs were refined, and detailed shipment procedures were developed. Background Surface coal mining of subbituminous C rank coal in the Cillette. (Campbell County) Wyoming area has become increasingly competitive during recent years. Prior to 1974, one small surface mine produced coal for local consumption. During the last ten years, 13 new surface coal mines have been constructed. Coal production from Campbell County, Wyoming totalled 88 million short tons (79.8 million metric tons) in 1983, the majority being shipped to electric utilities in the central and southern United States via unit trains having a capacity of 10,000 short tons (9,072 metric tons).

Jan 1, 1984

By Lee J. Raabe

A specialized loading system for tensile and fatigue testing of wire rope was constructed and installed in the U.S. Bureau of Mine Wire Rope Test Facility in Bruceton, Pennsylvania. The computer-controlled closed-loop servo-hydraulic test system which can apply up to 800,000 pounds of force on the rope while stretching it up to 30 inches will be used in the development and verification of hoist rope retirement criteria for ropes in the 1 to 2 ½ in. diameter range. Characteristics and capabilities of the system are discussed.

Jan 1, 1984

By B. C. Haydon

Manganese silver ores are well known to be refractory towards cyanidation. Various processes have been suggested for improving the amenability of these ores. A sulfurous acid pre-leach is one such process. This paper traces the development and implementation of the sulfurous acid pre-leach process for the retreatment of manganese silver tailings at Tonopah, Nevada. An account of the test work program is presented, followed by a description of the operating plant and specimen metallurgical performance. The paper also summarizes the history of the Tonopah tailings, their mineralogy and makes reference to previous application of the sulfurous acid pre-leach process.

Jan 1, 1984