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By I. Iwasaki

A low-grade copper-nickel deposit, with an estimated size of 4.6 billion tonnes and with average analyses of 0.6% copper, 0.2% nickel, occurs in northeastern Minnesota. In addition to copper, nickel, cobalt, and precious metals, the Duluth gabbro contains magnetite, ilmenite, olivine, plagioclase and biotite. It is estimated that the flotation tailings that would be produced by a concentrator of optimal size to sustain a smelter would amount to 20 million t per year. The flotation tailings, having already been ground, warrant a closer examination for the recovery and utilization of potential by-products. The residual sulfide minerals and fibrous minerals may also be isolated and treated separately for useful purposes or for disposal in an environmentally acceptable manner. Two flowsheets were developed; one involving preconcentration by low- and high-intensity magnetic separation and another involving preconcentration by gravity concentration. The concentration methods for recovering and purifying individual by-product minerals were investigated. From their chemical, physical and mineralogical characteristics, the potential areas of application and marketabilities of each product fraction were surveyed.

Jan 1, 1983

By Howard M. Wells

Portfolio theory and the Capital Asset Pricing Model (Modigliani and Pogue, 1974) provides an investment decision rationale which takes account of the benefits of diversification in reducing effective risk, but this theory does not consider the financial capability of the firm to survive large losses if they should occur. The LL-curve theory (Wells, 1976) takes the latter consideration into account, but it does not provide for the effects of diversification. This paper pro- poses a general theory to account for both diversification and the financial capacity of the firm to underwrite the investment risks.

Jan 1, 1983

By Roy L. Klein

The production of synthetic fuels from coal has been pioneered by South Africa. South Africa made a decision in 1975, due to the threat of an oil embargo, to proceed with the construction of Sasol Two, then followed by Sasol Three. South Africa has large coal but little indigenous petroleum reserves. The indirect coal liquefaction process used by Sasol since 1955 is the only commercially demonstrated method available for producing transport fuels from coal. The new plants consume 27 million tons per year of coal from a single mine that now produces transport fuels in sufficient quantities for energy independence.

Jan 1, 1983

By Mike S. Ness, Allan G. Provost

High speed drilling, mucking, and hauling equipment was used in driving approximately 2.16 km(7100 ft) of lower power tunnel in quartz diorite for the Tyee Lake Hydroelectric Project near Wrangell, Alaska. The .91 m(36 in.) guage rail mounted equipment included a Tamrock 2-boom electric/hydraulic drill jumbo, a Haggl and 8HR mucker , and 3 Hagglund 115C shuttle cars. Several other innovative techniques allowed maximum advance rates of up to 17.5 m/day(57ft/day) in the 3 m(10ft) horseshoe section. Average tunnel advance was approximately 11 m(day(35.4 ft/day). The primary difficulties preventing full utilization of the equipment potential were the operators' "learning curve", the need for complete retraining of all personnel in the new methods, and minor sections of faulted ground.

Jan 1, 1983

By Michael A. Redfearn

The use of nitrogen in molybdenite flotation circuits is a relatively new concept utilized by only a few mines around the world. This paper briefly discusses circuit chemistry and the reason for its success. It follows the entire testing process which resulted in a sodium hydro-sulphide dosage reduction from 18.5 to 4.4 lbs/ ton (9250 to 2200 g/t) through to the final installation of an inert gas generator which will produce reagent savings in excess of one million dollars annually. A description of the various types of nitrogen generators commercially available is included.

Jan 1, 1983

By Mehmet Guney

[The Atlantis-II-Deep is a hydrothermal mineralization located along the median valley of the Red Sea at a water depth of about 2200 m. Extensive exploration of the metal-rich brine deep revealed a potentially mineable deposit on economic interest consisting of oxides, silicates and sulphides with considerable concentrations of zinc, copper, cadmium and silver. Geostatistics was applied to assess the most likely in-situ vague of the metal potential for economical exploitation. Semi-variograms were constructed to characterize the structure of the regionalized distribution of the geological parameters. Volume grades and thicknesses were determined by the kriging technique, avoiding systematically biased high or low grades, and then block .tonnages were computed. The estimation variances, distribution of errors and histograms of observed and kriged values in each grid Mock were also produced.]

Jan 1, 1983

By George K. Schenck

INTRODUCTION Recent advances in high-pressure water jet technology can be effectively employed in mining and tunneling. The new equipment is based on available industrial hardware such as pumps, nozzles, and rotary swivels and seals, and is compatible with present mining and tunneling techniques. Principal advantages of water-jet assisted cutting relative to standard cutting are higher production rates, lower dust levels, and reduced fines. When used on rock and coal miners, water jets mean that relatively smaller and cheaper machines can be purchased. If properly applied, the combined effect is lower cost and significantly improved health and safety. While commercial use of high-pressure water blast cutting and extraction of rock (and concrete) already has a firm foothold in Europe, application of this new technique is just beginning in America. This paper begins with current American applications of high-pressure water jets for drills, for slotting and channeling machines, and then discusses the emerging technology for initiating rock failure in conjunction with drag bits on coal plows, continuous miners and boom-type miners (roadheaders). The focus of this paper is use of high-pressure water jets for cutting rock. High-pressure water jet cutting utilizes water above 70 MPa and currently reaches to 300 MPa and above. Some informatfon is included on low pressure "wethead" coal shearers and boom miners with water pressure to about 15 MPa.

Jan 1, 1983

By Scott G. Britton

Traditionally, water removal has taken a backseat to many other coal mining functions. However, it is a vital part of the total mine support system. In many US coal mines, more tons of water are removed each year than tons of coal. An excellent discussion of general drainage characteristics can be found in Chapter 8 of Elements of Practical Coal Mining, published by SME-AIME. This chapter is organized into three major sections. These are: designing effective drainage systems; constructing the main mine pumping station (static system); and constructing a portable pumping station (dynamic system). Each topic presents a separate discussion of the elements a construction foreman or engineer should consider for effective installation and operation of the mine drainage system. In addition, a list of pumping equipment manufacturers is available to interested persons and follows these sections.

Jan 1, 1983

By Charles H. McGuirk

The Port of Conneaut, the largest bulk material handling and storage facility on the Great Lakes, is using the latest electronic and visual testing devices to augment and enhance its well established computerized preventive maintenance system. The results of this comprehensive program have been impressive. The remaining life of components can be accurately forcast, and replacement can be programmed around operations, resulting in a significant improvement in system availability and reduced costs for the dock operator and its customers.

Jan 1, 1983

By V. F. Hollister

Computer programs developed as part of the PROSPECTOR project at SRI International can indicate where the highest grade hypogene copper occurs in porphyry copper prospects. The programs are useful in selecting drilling targets in untested porphyry deposits. Because of mineralogic, structural and lithologic variations in porphyry-type deposits, three distinct computer programs have been constructed; however, this paper considers only the stockwork type in homogeneous rock (similar to the Lowell and Guilbert model). The programs represent models in the form of inference networks that utilize the mineralogic, alteration, lithologic, structural, geochemical and geophysical data normally collected prior to a drilling decision. One example of an application of the PROSPECTOR program for a stockwork-homogeneous porphyry is given: Island Cooper in British Columbia. Computations based on the surface geologic, geochemical and geophysical data for Island Copper clearly disclose the best hypogene grade of the deposit. Other deposits were tested in the programs as well, and in each case PROSPECTOR programs indicate the region with the highest hypogene grade.

Jan 1, 1983

By Jack D. Melin

The commercial development of the Liwell Screen is a result of a thorough search for a non-blinding and highly efficient screening device capable of handling even the most difficult-to- screen feed materials. A proprietary development of Hein, Lehmann A.G. of Duesseldorf, West Germany, the Liwell Screen utilizes a unique flexible deck motion for sizing a variety of sticky, high surface moisture feed materials including raw coal and lignite at separations ranging from 3/4-inches (19mm) down to 10 mesh (1.5 mm).

Jan 1, 1983

By Joseph M. Chelini

Today, the two major operating costs of rubber tired off-road equipment are diesel fuel and tires. Mine Management has minimal control over the ever accelerating diesel fuel costs. However, they can exercise control over abnormal tire costs. Fortunately, with available technology and cost analysis methods, experience shows us the outlook for controlling tire costs is encouraging. Most earthmoving operations using off-road, rubber tired haulage and support equipment have abnormally high total tire costs. These costs, utilizing Tire Information Management, have been reduced more than 30%; 20% can often be guaranteed. Management Apathy on the subject of tires in a complex mining operation perhaps can be understood, but management apathy applied to an abnormally high operating cost, of which tires are, begs for a solution.' Tires have been professionally neglected for many years in most mine operations. This is exemplified in the January, 1982 issue of Mining Engineering by Charlie Son in his article Reducing Earthmoving Tire Costs. He compared the efforts to improve diesel engine costs to the same efforts given to earthmover tires.

Jan 1, 1983

By William P. Lorenz

The paper describes a uranium by-product recovery plant operating within a copper leach, solvent extraction, and electrowinning circuit. The operation is unique because it is integrated into the main process stream of the copper circuit The plant processes 1408 m3/h of copper solutions containing about 10 mg/L of uranium. An Eluex type process was selected due to its compatibility with the copper leach plant. The paper includes an overview of the copper circuit

Jan 1, 1983

By Michael G. Zabetakis

Effective accident prevention programs utilize a broad spectrum of activities, including meaningful training programs. In practice, such programs must be directed towards specific, defined needs. These needs are considered here for three categories of employees: new, re-assigned, and experienced.

Jan 1, 1983

By Atmesh K. Sinha

The demand for thermal coal both nationally and internationally is projected to increase rapidly. The marketability of high ETU thermal coal produced in the USA is, however, limited by its high sulfur content. Fortunately, over 70 percent of the sulfur exists in pyritic form. The research conducted at Southern Illinois University indicates that over 90 percent of the pyrite can be removed by simple devices such as concentrating tables, cyclones, or froth flotation cells and the desulfurized coal can be blended with low sulfur western coal to produce EPA compliance coal. Thus, both the low BTU western coal and the high sulfur midwestern coal can be rendered competitive in the utility markets, here and abroad due to improved utilization.

Jan 1, 1983

By Scott G. Britton

The first section of this text delves into construction engineering techniques for successfully completing necessary underground production support projects. I will discuss alternative design concepts, installation practices, materials and material costs, completion time, and necessary labor for individual projects. The emphasis of this section is on describing each project thoroughly and providing a practical guide for the supervisor or engineer. There are four main construction categories for typical underground mining projects. These are: 1) Transportation of men and supply materials. This refers to track and wire installation and roadbed grading and ballasting. 2) Ventilation, composed of overcasts, man doors, regulators, and stoppings. 3) Drainage, including sumps, pumping stations, drainage networks, pumps, and face drainage. 4) Haulage of coal and rock from the face to the outside. The focus here is in the installation of belt lines, belt drives, transfer points, and vibrating bins/feeders. The first section shall fully discuss these four categories in regard to the construction engineer or supervisor designing, building, or improving a system. In addition, special projects such as surge bins, rotary dumps, and underground offices not classified under these categories will be discussed. For manageable purposes, I have limited the installation discussions to one or two approaches I feel have merit. The variation of installations in coal mining is endless, each with its own advantages and disadvantages. Therefore, the reader should not dismiss or restrict his thinking to only the approaches in the text. It serves as a guide only.

Jan 1, 1983

By Robert A. Pimentel

Dust is still a major problem in increasing production from longwall faces. Over the last decade, significant improvements have been made in the development of techniques for reducing dust exposure on conventional and continuous sections. But virtually no improvements have been made in dust control on longwall sections. It is true, that there are many more continuous mining sections than longwall sections in the United States and that the number of workers overexposed on continuous miner sections is much larger than the number on longwall sections. However, the problem on continuous miner sections appears much easier to solve and, in fact, we believe that the techniques are available to get virtually all continuous miner sections in compliance. The problems on longwall sections are much more elusive. Also, the number of longwall sections in the United States is expected to increase during the 1980's. Thus, dust control on longwall sections remains a formidable and important problem. Companies operating longwall sections with a dust problem are faced with the tasks of having to quantify the various dust sources, of selecting proper techniques to reduce the problem, of implementing the techniques and of evaluating their effectiveness.

Jan 1, 1983

By Hassell E. Hunter

The Wyoming Mineral-Conoco Crownpoint Project represents the first time that big hole drilling has been exclusively used to develop totally a privately financed mine below a depth of 1000 feet. Three shafts, one ten feet in diameter and two six feet in diameter, were successfully drilled to depths of 2243', 2188' and 2188' respectively and cased with hydrostatic designed steel casing. The largest shaft is to be used to handle muck and water from station excavation and enlargement of the other two shafts. A reverse circulation system with potassium chloride base mud was used for drilling. The mud was cleaned by settling in steel lined tanks with assistance by cyclone type separators. Deviation was monitored by gyroscopic surveying at 30 foot intervals and did not exceed 16 inches off plumb. Casing was designed to withstand hydrostatic pressures with a 1.5 safety factor to the large shaft and 1.25 safety factor for the smaller shafts. All casing welds were x-ray tested prior to lowering the casing in the hole. Cementing the annular space completed the operation. The total time to mobilize, drill and move off the three shafts was 363 days. The drilling operation was completed ahead of schedule and under budget.

Jan 1, 1983

By K. A. Natarajan

The relative significance of corrosive and erosive wear in magnetic taconite grinding is examined. The influence of different types of aeration, namely, nitrogen, air and oxygen on ball war was established for mild steel and high carbon low alloy steel balls. Ball wear data from dry and wet grinding tests are compared with those obtained in the presence of an organic solvent that does not promote electrochemical corrosion. 'Marked ball grinding, tests along with electrochemical measurements involving ball material and magnetite electrodes indicate that contribution from oxygen towards wear (corrosive wear) is relatively small and abrasive wear appears to be significant. Rheological properties of the slurry-appear to have an important bearing on the abrasive wear of grinding balls.

Jan 1, 1983

By Klaus Stoss, Bernd Braun

The sinking and lining of a large mine shaft with 8.0 m i.d. and 1,133 m total depth is described in detail. The ground freezing method was applied to safely sink the shaft through unstable, waterbearing strata. Following a brief introduction to the geological and hydrological conditions and the owner's shaft requirements, is the general technical concept to sink and line the shaft. Particular emphasis is put on the lining system which has to provide stability and absolute watertightness for the lifetime of the shaft, even though mining takes place in its immediate proximity. Machinery and equipment used to execute the work are mentioned and commented. Furthermore, the excavation and lining of the large filling stations using rock anchors and shotcrete are described. Details on performance rates are given.

Jan 1, 1983