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By David G. Borg, John Bussey

The new AIRDEK (tm) technique for pre-splitting in surface coal mines produces highwall conditions that have greater safety with lower costs for explosives, labor, and drilling. Successful applications have been made in highwalls ranging from 20 to 100 feet or more and in blasthole diameters from 3-1/2 inches to 12 inches.

Jan 1, 1988

For tax purposes a mining company is a New Zealand company whose principal source of income is from the business of mining, or exploring for certain specified minerals in New Zealand. New Zealand tax law distinguishes between a non-resident mining operator and a mining company, with the only major difference in tax treatment being the corporate tax rates. New Zealand mining companies are taxed at 28 per cent, whereas non-resident mining operators are taxed at 33 per cent of taxable income. These provisions also apply to the petroleum mining industry. Individuals who carry on the business of mining are also specifically defined in the Act. They are termed as 'resident mining operators'. Non-resident mining operators are non-residents of New Zealand who carry on mining ventures as a business in New Zealand. Mining ventures are defined as the exploring, searching and mining of specified minerals, including development work carried out for profits. Similar provisions apply to the petroleum mining sector. Specified minerals are defined in the Income Tax Act 1976 ('the Act') and while no useful purpose is obtained by listing them in the paper, they include a larger number of industrial and commercial minerals. The Minister of Finance is also empowered to add to the list by publishing his determination in the Gazette.

Jan 1, 1988

"This paper describes some of the methods and equipment used for fine milling of minerals, and gives particular attention to the Vibro Energy system.In addition, the paper describes a specific application in the gold mining industry. This is the 200 tpd plant built by Anglo American Corporation at the President Brand Mine in South Africa in 1985, now a division of Freegold. This plant treats a gold bearing pyrite flotation concentrate which is finely ground to 15 microns prior to cyanidation and carbon-in-pulp (CIP). l .0 INTRODUCTIONFree milling gold ores are those that yield acceptable dissolution and recovery of the gold following grinding to what can be described as normal fineness, frequently between 50% and 90% passing 74 microns.Increasingly, gold metallurgists are faced with ores that are refractory. The traditiona1 treatment route for refractory gal d ores and concentrates has been by roasting, but for environmental reasons this is becoming less acceptable, or in some areas of the world, totally unacceptable. New methods of treating refractory gold ores are being developed and applied in practice. These new methods include pressure and biological oxidation. Higher gold liberation can also be attained by increasing the fineness of grind, although with conventional systems there are economic limits to this.In flowsheet development and test programs on new deposits, a standard procedure is to establish the relationship between the grind and subsequent go 1 d extraction. The normal situation is that gold extraction increases as the ore, or concentrate, is ground finer. Typically, this relationship is as shown in Fig. l, where the incremental additional extraction is very small once an optimum, or economic, grind has been achieved. This generally app1ies whether the material is free milling or refractory. The limits to grinding are set by the type of equipment which is commonly in use, usually ball mills. These mills have the obvious advantage of high capacity, however, they are increasingly inefficient as finer grinds are required. In general, ball mills are used to reduce ore to some agreed percentage passing 74, or possibly 53 microns."

Jan 1, 1988

By David C. Yang

A packed column (or static tube) flotation system is an innovative technology which utilizes a controlled dispersion reagent scheme and a new machine. The unique aspect of the machine is its packed-bed design permitting an unlimited froth bed height with countercurrent water washing for effective processing of fine particles. In operation, the conditioned ore slurry is fed into the middle section of the column where separation processes begin. Air, introduced at the bottom of the packed column, contacts the hydrophobic particles and floats them off continuously as the feed is added, while the gangue sinks to the base of the column. The system functions efficiently because intimate particle-bubble contact is achieved by the packing design which has no moving parts and requires no ancillary air-bubble generator. Other attractive features of the packed column flotation include high throughput, low power requirements, and simple control. Results from laboratory and pilot plant tests of this system show remarkable improvements over current industrial practices on a wide variety of ores and coals.

Jan 1, 1988

By C. J. Hall

I would like to congratulate Professor Gershon on an idea that is obviously valuable and is certainly new to me. It has, however, to be further developed, in that one can get fallacious results by limiting oneself to positional weights. In the example problem, the positional weight of one block was 8.6 (the 8.0 value in the paper was incorrect) for 36 units in the cone, for a mean block value of 0.239. The positional weight of the second block was 4.4 for 15 units, for a mean block value of 0.293. Surely one would expect the second block to be rated higher. Additionally, the time value of money adjustment cannot be determined by depth, because the time that a block is mined is determined by the mining sequence, not depth. Figure 1 shows a slightly altered version of Professor Gershon's pit. The overall value of the pit is the same, as are the total values under each of his blocks. The values in the right-hand cone have been reversed top to bottom, and the values in the rest of the pit adjusted to keep the central cone total unchanged. All values have been multiplied by 10. Figure 2 shows the sequence of mining, at three blocks per year, for Professor Gershon's pit, and Fig. 3, the sequence for a pit under the other block. Table 1 shows the value and discounted value (15%) of Professor Gershon's pit, and Table 2 shows similar values for the second pit. It is apparent that the second pit schedule is more valuable than the first.

Jan 1, 1988

By Witkowski A

I have the pleasure to present 6 excellent papers in this section all of major relevance to the mining environment of today where competing social, legal and monetary interests and their often complex interaction require serious consideration. This is particularly true today where huge fluctuations in commodity prices makes mining a perilous undertaking while the world increasingly are becoming aware of the serious threat that mans activities has on his environment. The 6 papers deal with such complex issues as safety in an underground environment; How to protect sensitive wetlands well into the next century; The enormeous waterproblems in China and conflicting dewatering/water supply needs; Disposal of contaminated water in sensitive areas and the dynamic interaction between mining companies and legislation.

Jan 1, 1988

By Rudolf Keller

"EMEC Consultants is developing a process to extract oxygen, aluminum and silicon from lunar anorthositic soil. The process will provide oxygen in space for propulsion, aluminum as a structural material, and possibly silicon for the construction of solar cells.The evolution of the process concept in the course of our present NASA-sponsored SBIR effort is discussed. A molten salt electrolysis producing aluminum and oxygen is the central step; inert anode technology is to be employed. Silicon will be produced by reducing the anorthite, CaAI2Si20S' with aluminum. In a steady-state operation, all components of the ore added have to be removed from the process, and the removal of calcium is a major topic of our experimental studies.Utilization of Lunar ResourcesUtilization of lunar resources may play an essential role in the exploration of the solar system and the conquest of space. High costs are involved in overcoming Earth's gravity to supply missions in space. Even at a low projected cost of $ 300 for transporting a pound of payload into Earth orbit -- today's costs are many times higher -- it appears attractive to use resources in space to produce needed materials. Processing of lunar resources on the lunar surface is an obvious possibility.Oxygen is a product of major interest. It is required for support of human life in space. Even greater quantities may be needed for propulsion, to conduct further missions into space. To satisfy this demand for oxygen through lunar processing requires a quite different solution than to supply oxygen on Earth, where oxygen gas is abundant and easy to extract from air or water. On the lunar surface, solid oxide materials have to be used. Hydrogen reduction of ilmenite and subsequent electrolysis of the resulting water is being studied [1]. Other suggestions include fluorination of lunar soil [2], reduction with lithium and electrolytic decomposition of the resulting lithium oxide [3], and aqueous HF leaching [4]."

Jan 1, 1988

By K. Barr, F. Grenier, J. Hettinger

"To reach the Hemlo Gold Inc. objective of becoming the lowest cost, safest Canadian gold producer while causing no environmental damage, management embarked from its inception on a strategy to build an organization which would foster employee involvement wherever possible. This paper describes the organizational structure and how various innovative concepts have been implemented.BACKGROUNDThe Golden Giant Mine in the Hemlo area of North Western Ontario is owned by Hemlo Gold Mines Inc. 50.1% is controlled by Noranda. The mine commenced operations in March 1985 at a modest production rate. After it reaches full production by the end of 1988, with completion of underground development work, the mine is expected to operate at 3000 t/d and produce in excess of 300,000 ounces of gold per annum. This makes it one of the three largest producing gold mines in North America.Two other companies, Lac Minerals and Teck-Corona, operate mines on either side of the Golden Giant Mine. Noranda Geco Division is located 55 kilometers to the north at Manitouwadge. The majority of Hemlo Gold's 270 employees live in Manitouwadge where a mix of accommodation was constructed and made available for purchase by employees. Bus transportation is provided to and from the workplace with modern coaches. The housing and transportation policies were implemented prior to start-up and designed to help attract and maintain good employees.As shown in Figure 1, the operation is divided into five operating and support departments with each reflecting a high degree of departmental control and responsibility. For example, the mill department is responsible for all aspects directly relating to the milling complex including safety, operation, mechanical maintenance, assaying, instrumentation, and environmental control. Similarly, the mine department is responsible for all phases of operation, mine engineering, geology, and maintenance of underground mobile equipment. The plant department is responsible for maintenance of hoisting plants and conveyances, underground stationary equipment, all site electrical services, surface buildings, housing and yard maintenance. Efforts are made at every level of the organization, from departmental organization to individual job assignments, to ensure responsibilities are clear and that they encompass complete functions."

Jan 1, 1988

By R. E. Ray

As coal reserves at shallow depths continue to be exhausted, a number of US coal companies are developing seams previously considered too deep to mine economically. Because of increased cover load, mines operating in deeper seams face unique ground control problems. In addition, the volume of methane gas in coal beds increases with depth, and ventilation requirements are much more stringent for deep mines than for shallower mines. When the longwall mining method is wed at great depths, ventilation, ground control, and operational considerations all influence the design of longwall panels. This paper examines these influences, particularly ventilation and operational considerations, on the feasibility of two-, three-, and four-entry longwall development panels in Jim Walter Resources' four deep mines.

Jan 1, 1988

By O. J. C. Runnalls

"Canada became the world's largest uranium producer in 1984. That leadership position is likely to be maintained for many years into the future because of a firm production base, many undeveloped known deposits with commercial promise, and a large geologicalpotential for new discoveries.There are some uncertainties on the horizon, principally because of restrictive actions in process within the U.S.A., which are aimed at preserving a deteriorating domestic uranium industry. Should such actions result in import restrictions, for example, there would be a negative effect on foreign producers at least in the short term. Canada may avoid such difficulties under a tentative U.S.-Canada free-trade agreement where restrictions on the import of Canadian uranium into the United States would be eliminated. Over the longer term, demand for Canada's uranium resources will grow because of the foreseen growth in the world's installed nuclear power capacity. IntroductionSince the phenomenon of nuclear fission was discovered in 1938, the utilization of uranium has grown substantially. Initially, the principal use for uranium was in the production of nuclear weapons. However, once civilian nuclear power reactors began to be built in the 1950s, an increasing fraction of uranium output was directed to the production of fuel elements for use in electricity generating stations.The cumulative uranium production by those countries in the World Outside Centrally-Planned-Economies Areas, WOCA, during the period 1938 to 1985 exceeded 800 000 tonnes of uranium. Some 60% of that was mined in the United States and Canada, as indicated in Figure 1. In 1986, nearly 80% of WOCA output came from five countries, Canada, United States, South Africa, Australia, and Namibia, as indicated in Table 1 and illustrated in Figure 2.During the past decade the world annual consumption of nuclear energy has more than tripled (Fig. 3). As of December 31, 1986, the world total of nuclear power reactors had reached 394 with a total net capacity of 270 GWe. The thermal output from nuclear power plants in 1985 exceeded 60% of the energy contained in all of the oil produced that year in the Middle East. Thus, nuclear power has already become an important component in the world energy supply picture."

Jan 1, 1988

By Wilton Johnson

Native asphalt was produced by three companies in two States, Texas and Utah. Bituminous limestone, used primarily as a paving material for street and road repair, was produced by one firm, R. L. White Co., Uvalde County, TX. Gilsonite, a solidified hydrocarbon found only in Colorado and Utah, was mined by two firms, American Gilsonite Co., a division of Chevron Resources Co. (a subsidiary of Standard Oil Co. of California), and Ziegler Chemical and Mineral Corp. Hydrocarbon Mining Co. (a subsidiary of Oberon Oil Inc., a Utah corporation) closed its mining operation during the year.

Jan 1, 1988

By J. M. Krese

This paper gives an overview of the National REAP program emphasizing the program's current status and future plans. A brief historical review of the program will be given containing roof-fall accident trends and statistics. The latest developments in roof control technology and training as it affects the REAP program will be presented. A brief discussion concerning some effects of the implementation of the amendments to Part 75, CFR, concerning roof support is included.

Jan 1, 1988

"INTRODUCTIONThe Kidd Creek Concentrator is located 28 kilometers east of the city of Timmins, Ontario. Two types of ore are treated; 'A' type, a copper-zinc-low silver ore producing copper and zinc concentrates, and 'C' type, a copper-lead-zinc-high silver ore producing copper, lead and zinc concentrates.The ore is processed at a combined rate of 12,400 metric tonnes per day through four parallel grinding and flotation divisions. Three divisions treat the 'A' type ore and the fourth treats the 'C' ore. Each division is fed from its own fine ore bin.This paper reviews the grinding section with specific emphasis on grinding media consumption and the factors affecting it as related to 'A' type ore. At Kidd Creek there was an awareness that grinding media consumption varied on a weekly and monthly basis. The reasons for this variation was usually attributed to ore hardness as evidenced by short term variations in the circuit feedrate and head assays. However, there has been a diversity of opinion published in recent years regarding the factors contributing to steel consumption. This initiated a study of historical Kidd Creek operating data, from the period 1970 to 1986 inclusive, to determine the effect of various operating parameters on media consumption. The results of the study could then be used as a baseline for future media consumption testwork."

Jan 1, 1988

By K. J. Griffin, G. W. Rosval

"In our increasingly competitive market, attempts to improve productivity by increasing axle loads have placed more severe demands on rails. CP Rail thus requires stronger, tougher, and more wear-resistant rails from steel manufacturers. The choice of any rail steel is always a compromise between technical and economic factors. The technical assessment of a candidate rail consists of laboratory and field testing. Laboratory evaluation of rail steels cannot adequately model many service conditions and must, therefore, be supplemented by long-term field testing. The field testing conducted on CP Rail is the subject of this paper.Long-term, in-track, assessment of candidate rail steels begins with the selection and re-laying of a test curve representative of the intended service with both the candidate rail and a control rail steel (i.e. the present intermediate or premium rail standard). The wear performance of the candidate rail is evaluated, in relation to that of the control rail, using data obtained with a rail profilometer developed by the Research and Development Department of CP Rail. Qualitative observations are also periodically made to evaluate the relative susceptibilities of the two rail types to surface defect formation. Testing continues until stable metal loss patterns are achieved. Relative life predictions are then made and detailed monitoring of the test site is discontinued.CP Rail's in-track assessment program for premium rails has resulted in the establishment of a new CP Rail premium rail standard - low-alloy, head-hardened, rails have replaced high alloy rails. The wear/fatigue lives of these new premium rails exceed those of our previous standard by more than 50%, and they also exhibit excellent weldability. CP Rail will continue to evaluate new premium and intermediate strength rail products."

Jan 1, 1988

By Hamid N. Maleki

Cooperative efforts by the Bureau of Mines and Agapito & Associates, Inc., Grand Junction, CO, achieved the research objective of showing that data from measurements of the rate and change in rate of mine roof movement can be effective in detecting roof instability. Several instruments and techniques have been used to monitor roof movement and to detect imminent roof caves during pillar robbing. Early detection of unstable conditions can provide time either to withdraw personnel and equipment or to allocate supplemental support to prevent injury or down-time. Critical convergence rates were determined both manually and electronically. The detection of critical rate of movement has been shown to be an effective tool in ground control efforts.

Jan 1, 1988

By Gregory M. Molinda

Coalbed discontinuities historically have been hazardous to mining as well as obstructions to efficient production. An effective means of mapping these features is needed in order to plan safe and efficient mine development. This Bureau of Mines report discusses the use of surface seismic techniques for this purpose. At a southwestern Pennsylvania mine, a system of coalbed discontinu-ities (paleochannels) was accurately mapped by the Bureau of Mines using borehole log methods and underground observation. This site was chosen to test the value of a high-resolution surface seismic reflection on technique for coalbed mapping. A statistical study performed at this mine indicated that the probability of accurately delineating this paleochannel system with conventional borehole methods was remote. A total of 1.47 miles of high-resolution seismic survey, comprised of four seismic profiles, was conducted in known and suspected coalbed discontinuity areas. Several test holes were drilled on the seismic lines in order to evaluate the interpretations. It was found, based on these and other existing boreholes, that it is possible to predict these dis-continuities. Paleochannel washouts were correctly predicted in several instances but in other instances were either incorrectly predicted or not predicted in areas of known discontinuities.

Jan 1, 1988

The Mount Sisa orebody on Misima Island, P.N.G., consists of goldsilver mineralisation associated with massive carbonate and amorphous iron-manganese oxides in fractures and breccia matrix. The orebody forms the northern extension of the Umuna deposit, which lies within a three kilometre strike length of a northwest trending, 300 metres wide, high angle fault zone. The structure is deeply oxidised, with the magniferous oxide material resulting from oxidation of carbonate. The wallrocks are metamorphosed basement psammopelites and basic volcanic rocks, extensively intruded by microgranodiorite. These are dominantly epidotised and sericitised. The precious metals are associated with anomalous Cu, Zn, Pb, Mn, As, Ba, Ga, Sb, and Mo. Many of the features of the Mount Sisa mineralisation are characteristic of volcanic-hosted epithermal deposits of western North America.Lithologic and textural gradation is observed between the carbonate hydrothermal breccia-fill at Mount Sisa, and the quartz dominated brecciafill and dilational fracture-fill mineralisation which forms most of the Umuna deposit to the south. This gradational relationship is analogous to that in the Amethyst-OH vein system at Creede, Colorado, where it is shown to be indicative of deposition from laterally migrating fluids.

Jan 1, 1988

By R. K. Singhal, R. Kolada

A variety of equipment is wed to surface mine oil sands, including bucket wheel excavators/conveyors, draglines, hydraulic shovels, and off-highway trucks. This paper examines the existing mining schemes and equipment wed. Several proposals to improve mine productivity have been presented.

Jan 1, 1988

By Fangting Dong

The broken rock zone (BRZ) and the tunnel support theory are investigated. The relationship between the BRZ and the related factors, the interaction between the BRZ and supports, and the function of supports are analyzed in detail based on the authors' underground observations and model taste. A summary of the application of the BRZ theory in the past is also presented.

Jan 1, 1988

By J. E. Nesset

"This paper discusses the importance of considering residence time distribution (RTD) in the design of flotation and mixing circuits and in the analysis of operating problems. The experiences and successes of Brunswick Mining in this area are covered and include: the development of a practical RTD measurement technique using pulp conductivity, baffle installation to improve the RTD of existing process equipment, and the method in which RTD considerations have been used to design the newest flotation and conditioning operations. IntroductionThe use of residence time distributions (RTDs) in the design and analysis of unit operations is well understood by the chemical engineering profession in while mineral processing engineers have tended to rely on empirical and rule-of-thumb factors. For example, in scale up from laboratory and pilot test results to full size flotation plant design, empirical rule s are often used to establish residence time and number of cells in the bank. Coleman suggests a factor of at least 2, and up to 5 for gold ores, be applied to laboratory determined flotation times. This is further illustrated in Table I, taken from Denver equipment.The number of cells in series to achieve the required retention time while minimizing short-circuiting has generated a variety of conclusions (Table 2). Obviously there is less than complete agreement on the subject. Young notes that a clear difference of opinion has emerged and cites as extremes, (i) the publications of Outokumpum showing unimpaired recovery for its largest machines (38 m3) compared to equivalent retention times for numerous smaller machines, and (ii) the experiences of Eastern European countries where the practice is to install banks of 30 unit s or more, operating in series, often with unit retention times of only a fraction of a minute.The empirical factors used by engineers presumably account for other than tested feed conditions, inefficiencies in large continuous machines, inevitable day-to-day circuit disruptions, gradual equipment deterioration and any other safety factor the engineer feels compelled to incorporate. An understanding of RTD concepts and techniques should help the practicing mineral engineer to develop more soundly based factors. This paper relates the experiences of Brunswick Mining in using RTD techniques in the unit operations of flotation and mixing."

Jan 1, 1988