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By M. C. Esposito

Seven pyrite samples purified from coal sources and one ore source pyrite (for comparative purposes) have been characterized by chemical and mineralogical analyses, inherent floatability, apparent specific gravity, surface area, semiconductor type, optical anisotropy, dissolution and oxidation rate. The data clearly demonstrate that pyrites from various coal sources differ not only from ore pyrite but from each other as well.

Jan 1, 1987

The Porgera gold deposit in the Papua New Guinea highlands contains about 387 tonnes of gold. The results of its exploration show the benefits of persistence and commitment to this difficult deposit. The mineralization consists of a complex intermix of auriferous and argentiferous sulphides, gold tellurides and free gold as disseminations, veins, stockworks and breccia matrix. Its deposition was structurally contolled within a system of mafic diorite intrusions and adjacent sediments. Two styles of alteration accompany the mineralization. Gold grades vary erratically throughout the deposit. Over a period of 22 years nine phases of exploration have been undertaken by six companies or consortia of companies. Surface rock chip sampling, geological mapping followed by scout and systematic grid diamond drilling have been the most successful exploration tools. Exhaustive metallurgical process investigations and economic evaluations of mining options have been invaluable in guiding the exploration towards defining the ore body. Impetus was given to the project during times of flagging enthusiasm by several important discoveries and a breakthrough in the metallurgical processing approach. The discovery of high grade ore deep in Zone VII in 1984 turned this marginal deposit into a potentially very large gold mine.

Jan 1, 1987

By Peter G. Kovalchik

To compare the viability of the new fuse wire arc test (FWAT) as a substitute for the comparative tracking index (CTI) for determining surface resistance to electrical tracking, the Bureau of Mines constructed a fuse wire arc tester and undertook a detailed testing program for testing insulating materials used on explosion-proof enclosures. This report describes the Bureau's apparatus, the two methods (CTI and FWAT), and the results of the Bureau's testing, showing comparisons of the FWAT with the CTI. Results showed strong correlation between the two methods, as all specimens tested that had CTI ratings of 400 V ac rms and above passed the 10-test sequence with the FWAT, whereas all specimens with lower CTI ratings failed, with the number of tests to failure corresponding roughly to the descending CTI rating order.

Jan 1, 1987

By R. Jacobson

This paper presents comparison of proposed future solution and in-situ mining methods for in-situ leaching and recovery of uranium, gold, silver, and copper. We propose to show that in the future new extraction methods for each metal will eventually evolve for each hydrometallurgical process step, i.e. in-situ leaching, recovery, and concentration; precipitation and reduction; and drying, when required--without generating waste or bleed streams. In the future, to be highly profitable, these forms of mining will develop into an integrated system to eliminate waste streams using safe, powerful lixiviants. This integration will include, with some exceptions, improvements in the following areas of process development: 1. Lixiviant selection and in-situ leaching technique, 2. Target metal recovery and concentration (at a surface hydrometallurgical facility) from the circulating pregnant lixiviant stream, 3. Target metal precipitation or reduction, where decant water from the precipitate dewatering step is reusable for resin or solvent strip liquor (eluant), 4. Final preparation of target metal for sales, i.e. drying, purification, casting, packaging, 5. Restoration where most of the groundwater restoration process is performed at the same rate as multi-wellfield mining.

Jan 1, 1987

The Colorado portion of the Rio Grande rift is clearly defined physiographically from the south in the San Luis valley northward to the latitude of Leadville where sediments of the Dry Union Formation (Tweto, 1961) accumulated within the subsiding rift zone. To the north of Leadville is a system of faults active in the late Tertiary, including the Mosquito fault that offset a portion of the Climax mineralization (Wallace et al., 1968). Tweto (197B) describes remnants of Dry Union Formation against the Mosquito fault north of Dillon in the Blue River valley, so it is apparent that the rift and associated sediments extended well to the north of Leadville. Kelley (1952, 1954, 1956) and Chapin (1971) have noted in New Mexico that the Rio Grande rift is a series of en echelon basins, offset to the east, with constrictions connecting them (Fig. 1). In Colorado the structural basins are offset to the west. The net effect of all the rift zone basins in New Mexico and Colorado is an arcuate pattern (Fig. 1) abutting the Colorado Plateau and Sari Juan Volcanic Province on the west. The width of the rift system gradually decreases northward to about Leadville where rift definition is not apparent.

Jan 1, 1987

By Kenneth L. Bickel

During an underground mine fire, the importance of controlling the spread of smoke and toxic gases with suitable ventilation structures has been proven. However, under certain conditions, control of the propagation of the fire itself may be even more critical in insuring a safe mine evacuation. Fire doors offer the means for accomplishing both objectives. In 1978, the Bureau of Mines initiated research to evaluate the state of fire-door technology and develop and test a fire door suitable for large openings (10 by 12 ft or larger) in noncoal underground mines. This report discusses current fire-door technology in the context of the underground mine environment and the design, fabrication, lab testing, and in-mine field testing of a mineworthy fire door. This door has a 1.5-h fire resistance rating and limits temperature rise across the door to 2500 F during the first 30 min of fire exposure.

Jan 1, 1987

By C. M. Flynn

The solubilities of sideronatrite [Na2Fe(OH)(SO4)2?3H20] and ferrinatrite [Na3Fe(SO4),&apos;3H2O] were determined by the Bureau of Mines in the Na2SO4-Fe2O3-H2SO4-H20 system at 25°, 40°, 60°, and 90° C. The solution compositions investigated ranged from Na+-Fe&apos;+ mol ratios of 0.5 to >100 (Na2SO4 saturation) and H+ -SO4 2-mol ratios of 0 to 1. O. The results are presented in the form of contour plots. The solubilities were determined by seeding supersaturated solutions of known composition with the specified solid phase to precipitate a substantial amount of solid. Water was then added in small portions to the solution until the last portion of the solid dissolved. Equilibration times at 25°, 40°, 60°, and 90° C were 2 days, 1 day, 8 to 16 h, and 2 to 4 h, respectively. The accuracy of the solubility data is estimated to be 1 to 2 pet. Low iron solubilities of <0.36 pct Fe2(SO4)&apos;, or 1 g Fe/kg solution, were obtained in solutions containing at least 8 pet Na2SO4 in the absence of H2SO4 or a total of at least 36 to 38 pet Na2SO4 + H2SO4 at high acidity. The filterability and density of sideronatrite and ferrinatrite in comparison with other iron compounds are reported. These compounds are suitable vehicles for iron removal in Na2SO4-rieh solutions. Additional solubility data on the Na2SO4-H2SO4-H20 system were also obtained.

Jan 1, 1987

By L. Adler

A systematic, balanced and inclusive formulation of the vast input data for mine design is presented. Since the quality of this statement severely influences subsquent design it is extremely important to senior mining engineers and the profession-at-large. If unfocussed, chaos can result along with serious ommisions. The basic categories, each a traditional one are: 1) Natural Conditions (geology and geography), 2) Company Capabilities (monetary and managerial), 3) Public Domain (regulations, contracts, good will, etc.) and 4) State of Art (mining engineering professionalism). To further reduce the data additional organizing principles were used: the distinctions of mining (vs. civil) engineering, proceeding from the general to particular, the basic engineering dimensions, and separating dependent from independent variables. The results are a unique and unified corpus, which anticipates the mine design procedure.

Jan 1, 1987

By D. A. Norrgran

The process of magnetic separation is based on the differences among magnetic susceptibilities of various mineral species. Performed either wet or dry, the separation has application in both the recovery and concentration of value minerals and in removing deleterious mineral constituents from a product stream. There are two major catagories to be considered when addressing magnetic separation of minerals. The first catagory refers to particle characterization and relative differences in magnetic susceptibility. The second catagory refers to design parameters and the magnetic field generated by the separator.

Jan 1, 1987

By A. P. Van Wyk, G. Pirnaar

The effect of vanadium on the susceptibilities of chromium and chromium-nickel steels to reversible temper embritlement was evaluated. The steels investigated were approximately equivalent to steels of as 970 Grade 708A42 and as 970 Grade 817M40, the major difference being that molybdenum had been replaced by vanadium in various concentrations. It was found that the vanadium had a detrimental effect and, in al the concentrations tested, enhanced the susceptibility to reversible temper embritlement of both the chromium and the chromium-nickel steel. The detrimental role played by vanadium in reversible temper embritlement is explained by a consideration of the effect of vanadium carbide, as well as of free vanadium, in solid solution in ferrite.

Jan 1, 1987

By A. Christlo

Short circuit detection in 1984 involved nine inspectors for production rates of 43,000 tpa. Trials indicated the feasibility of applying cell voltage monitoring to short circuit detection and improving operational efficiency. A computerised cell voltage monitoring system was commissioned in February 1986, to read voltages from 648 cells. The system incorporates 16 evenly distributed work face units which communicate with a central computer system. Provision has been made in the computer program for the automatic adjustment of cell reference voltages. This allows for the effect of polarization and other process variables which might other wise interfere with short circuit detection. The work face units can continue to work independently for several days should this become necssary. Current efficiencies have been maintained and the number of inspectors reduced from nine to five.

Jan 1, 1987

This paper is directed at the problems flowing from Australia&apos;s capital gains tax (CGT) on the disposal of exploration and mining tenements both in Australia and overseas. It will seek to identify the issues and give some idea of the dollar consequences of decisions lacking forethought. The paper should not only be seen in the context of Australian tenements. CGT applies to the disposal of any assets by an Australian resident anywhere in the world. Offshore incorporated companies are not necessarily free from CGT risk where it can be shown that control management and control of the relevant company is in Australia. Also the disposal by non residents of Australian tenements are potentially caught by CGT. Some will ask what has taxation got to do with a valuer who merely determines the value of assets. These days no determination can be blind to the consequences. Whether the consequences can encourage a movement in value is another thing dependent upon the circumstances; but? A role of an experienced taxation consultant is to point out parameters within which associated professionals can work. The parameters will vary from case to case, but these when clearly indicated may be of help to persons such as valuers. When one comes down to it real estate salesmen are never wrong. They have a feel for the market and almost through self fulfilling prophesies achieve sales at their guestimates. Whether they could have achieved higher considerations become virtually academic in the process. Of course I am not suggesting that tenement valuers can be compared to real estate salesmen, or am I? What is the value of a tenement? Is it the DCF/NPV type of generated value based on a large number of variable factors (ie what one may call the fundamental value)? Or is it what another may pay to purchase that tenement if it were on the market at an instant point in time? How big is the market, the quality of the bidders, the size of their purses, the needs of the buyer for comfortable fit, the premiums for foreigners, the standard of the marketing, the industry intelligence level of the bidders, the obligation to farm/sell down? The list goes on endlessly. One question must be.asked-"Is a range of values acceptable for tax purposes". ie Would any tax consultant ever provide a valuation to the Australian Taxation Office that indicates three or more possible values ie

Jan 1, 1987

By Sikko Doornbos

For the extension of the Paper Mill of Parenco in Renkum, the Netherlands, the application of a pile foundation was required. The demands for this pile foundation were very explicit a vibration free and soil displacing pile systems with low allowable settlement. Another important aspect was the total amount of piles (originally over 1600 auger piles) which had to be executed within 3 months, in very difficult and unhomogeneous soil. Based upon these conditions the Tubex Grout Injection Pile was chosen to be used for this project. This system involves the drilling of a steel tube with a conical pile shoe while grout is injected at the point simultaneously, creating a mixed-in-place layer around the tube. INTRODUCTION After extensive marketing, the board of directors of Parenco, decided to a large extension of the production capacity of its paper mill by building a new production building called Paper Mill 1 or PM-1. The new PM-1 extension had to be constructed beside the existing PM-2 because of limited terrain. The site is located right between the Rhine river and Renkum, approximately 15 kilometers (10 miles) west from Arnhem (see figure 1). The construction involved the building of the PM-1 extension of approximately 250 meters (820 ft.) long by 40-60 metres wide (130-200 ft.). The main structure was to be constructed of precast concrete beams and columns.

Jan 1, 1987

By J. H. Welsh

This Bureau of Mines report presents guidelines to be considered in the design, installation, and operation of environmental mine monitoring systems in underground coal mines so as to enhance safety in the U.S. mining industry. A review of the current status of mine monitoring in the United States is also provided.

Jan 1, 1987

By Donald Giroux

This report documents the design, fabrication, testing, and coal mine demonstration of a hopper-feeder-bolter during a four-phase program for the U.S. Bureau of Mines. The machine was designed to increase productivity and safety in under-ground room-and-pillar mining. It performed well as a hopper-feeder for continuous haulage during a coal mine demonstration. Testing in a simulated mine showed that the machine also has good roof bolting capability.

Jan 1, 1987

By Keith L. Harris

Real2 gross national product (GNP) grew at a seasonally adjusted annual rate of 1.3% in the fourth quarter and at 2.5% for all of 1986, according to the most recent Department of Commerce estimates table 1). The 1986 GNP growth was the lowest since the recession in 1982, and was slightly below the estimate published in the last issue of Minerals and Materials. Barriers to greater economic growth in 1986 included the Federal budget deficit, the trade deficit, reduced energy-sector investment because of low oil prices, and uncertainty over changes in the Federal tax code.3 Major sectors of the economy responsible for the fourth-quarter growth included real Government purchases of goods and services, up $19.9 billion from the third-quarter level; real net exports, up $12.2 billion; real residential investment, up $3.0 billion; and nonresidential fixed investment, up $1.5 billion. The increase in Government purchases of goods and services was attributed to the S25.1 billion rise in net purchases of farm products by the Commodity Credit Corp-oration. Real personal consumption expenditures and inventory investment declined, however. Personal consumption expenditures declined primarily because of reduced motor vehicle purchases. Despite only modest growth during the fourth quarter, the economy improved significantly because of the narrowing of the trade deficit and growing employment (table 2) while maintaining low unemployment and inflation rates. Business sounded an optimistic note, with planned increases in current-dollar capital spending of 0.9% for 1987 compared with a 1.7% decrease in 1986. While it is primarily the nonmanufacturing industries that expect to increase investment from 1986 levels, some manufacturing industries are increasing investment by significant percentages as well, notably the steelmaking and nonferrous metals industries (table 3).

Jan 1, 1987

By B. J. Timmons

An initial point that I would like to make very emphatically?and as our title might erroneously suggest for those of you old enough to remember . . . Peter Harben and myself do not intend to shoot ourselves in the foot. We derive our livelihood from a number of aggregate, industrial and other minerals producers, both here in the United States and outside. This paper, therefore, is a fence-straddler or for information purposes (we hope) only, rather than any "fur or agin" stances. In essence, some of you may consider it a U.S.G.S. publication! In fact, we hope that it serves to inspire aggregates producers to do some radical thinking, to promote introspection, and to that end it would benefit both domestic and foreign producers. The title could be shortened into a brief question of "Aggregates Travel?" with an emphatic no for the answer. In the past, the success of a construction materials venture depended upon your ability, through siting, to provide the customer f.o.b. the job site, a product at the lowest possible cost.

Jan 1, 1987

By Poul Hansen

"In mid-I986, a world-class mining enterprise was created in British Columbia, bringing together the copper mining operations of Lornex Mining Corporation and Cominco into a new entity, Highland Valley Copper. This paper will focus on the background and rationalef or the formation of this partnership, the resulting operating changes and the productivity and cost benefits expected.IntroductionSince the deterioration of the world copper industry in 1981, the future of the Lomex and Cominco mines in the Highland Valley of British Columbia looked increasingly precarious. Despite the expansion of the Lomex mill complex in 1981 to one of the world&apos;s most cost-efficient copper and molybdenum concentrators, persistent low metal prices had made the remainder of the ore in the Lomex orebody marginally economic and had significantly foreshortened the expected life of the operation.Cominco had acquired the Bethlehem Copper assets in order to consolidate its ownership of the Valley orebody, and was feeding the Bethlehem concentrator with ore from the Valley orebody. In spite of the high grade and free-milling character of the Valley ore, profitability of the Cominco operation was severely restricted because of the limited capacity of the Bethlehem concentrator and its location high on the hillside above the orebody."

Jan 1, 1987

By D. J. Murdock

Cominco Ltd. has developed a number of innovative technologies for electrowinning. The paper discusses the application of these technologies to the copper industry. Tankhouse and cell design will be discussed in addition to anode cleaning and cathode handling. Specific examples of the application of this technology to the copper industry are cited.

Jan 1, 1987

By T. M. Barczak

This report describes Bureau of Mines research to develop methods to evaluate loading on longwall roof supports to permit better design and more efficient utilization of these structures in compliance with the geological conditions in which they are employed. The resultant vertical and horizontal force acting on the canopy of a shield can be determined, either from a statically determinate solution assuming rigid-body mechanics and elimination of certain unknowns, or from an elastic solu-tion by analysis of the load-displacement relationship of the shield structure. A two-dimensional rigid-body model is presented that determines resultant shield forces by measurement of leg, canopy capsule, and lemniscate link forces. An elastic solution is presented, in the form of an elastic stiffness model with two degrees of freedom, which describes the load-displacement relationship from the stiffness of the shield structure as determined in the Bureau&apos;s Mine Roof Simulator (MRS). The ability of both models to determine resultant forces acting on the shield canopy are evaluated from full-scale tests in the MRS. More advanced numerical models are also discussed as part of the Bureau&apos;s continuing effort in the evaluation of roof support structures.

Jan 1, 1987