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By D. W. Mitchell

Never increase, reduce, or remove ventilation without unquestionable, compelling reasons. This rule applies every day as well as when fighting fire, attempting to find survivors, or recovering the mine. Right now in some mine a miner is adjusting a regulator in one place to get more air into another. The chances are the desired result will be achieved. Has the miner done a good thing? NO! Solving the immediate problem reinforces the belief he or she can do it again. That "again" might be, to give but one of many examples, the explosion in Greenwich No. 1 Mine. Robbing the proverbial Peter can be the prelude to disaster in a mine. Reducing the airflow is a common practice when fighting a mine fire. In fact, some people have been taught to do that at MSHA's academy. People who believe that to be proper must be people who never experienced a fire. To fight most fires you have to scramble to get enough air. An explosion demands totally different "thinking". If people are soon to go into the mine, DON'T adjust the ventilation. If teams are in the mine, each affected area must be explored or sealed before making any ventilation change.

Jan 1, 1993

By Sheila Luchansky, F M. Babcock, Daniel M. Sanders

A cooperative effort between a blasting vibration consultant, a blasting contractor, and personnel from the City of Las Vegas has dramatically reduced complaints from residential areas near developmental blasting projects. The principal methods used involved the preparation of an informative video recording which presents various aspects of the blasting operations, the design of a distinctive flyer which is attached to residential doors, and pre-blast meetings for information dissemination.

Jan 1, 1993

By Gunter Swoboda, Harald Wagner

Until a few years ago tunnel construction was based exclusively on experience. In recent years, however, numerical models have increasingly become an integrated part of tunnel design [2]. These models permit good evaluation of the tunnel's support behavior even before it is designed. In particular, numerical methods are highly suited for the development of new construction methods. The prerequisite for this is the application of high-performance pre- and postprocessors, permitting the design engineer to come to a quick interpretation of the analysis results. In future, 3D analysis will take on increasing significance, for which reason this paper also deals with this type of models.

Jan 1, 1993

By R. A. Winters

At the operations level, productivity is a principle key to profitability. If you are competing with other mines that are paying roughly the same wage rate and the same prices for capital, materials, and energy, the only way your profit can be greater is by producing more output per unit of input. Mines with higher productivity have higher profit margins. Higher profit margins lead to greater operating cash flow, and cash flow is what distinguishes a dog from a cash cow. The turnaround in U.S. metals during the 1980s was in large part due to incredible improvements in productivity. According to statistics compiled by Kaufmann, 1991, labor productivity, measured as tonnes of primary production/manhour, increased 64% in steel, 94% in copper, 75% in lead, 143% in zinc, 132% in molybdenum, and 75% in gold. These improvements were hard won. However, with most modernization programs now complete, measuring and monitoring productivity becomes even more important as producers strive to maintain the gains they have achieved.

Jan 1, 1993

By J. J. Bartels

The phosphate rock review did not arrive in time for publication in the. June issue. The world phosphate industry continued its slide in 1992 from the already depressed levels in 1991. The industry is locked into a 30-year fertilizer price low due to the worldwide fertilizer glut. Domestic production and imported, marketable phosphate rock decreased 1%, while domestic consumption increased by 1 % last year. The US Bureau of Mines reported a decrease in the domestic phosphate rock value from $25.42/t in 1991 to $23/t in 1992 ($23.06/st to $20.80/st). The diammonion phosphate (DAP) product price also dropped in value from $138/ t in January 1992 to $11 0/t in December ($125/st to $99.70/st). Continued declines in DAP prices is forcing the US fertilizer industry to develop cost-saving programs and reorganizations. Layoffs in 1992 resulted in a 7.6% decrease in the Florida phosphate workforce. Since 1980, the Florida workforce has declined by 35%. Small phosphate companies were forced to close operations or were sold to larger phosphate companies. Federal and state environmental regulations for byproduct waste disposal methods are being studied. The Environmental Protection Agency (EPA) approved phosphogypsum use in agri¬cultural and research applications as long as the radium 226 concentration is lower than 10 pci/g. The EPA is also reviewing regulations concerning air emissions at fertilizer plants. Industry publications reported the possibility of continued company sales and mergers in 1993. Industry expectations are optimistic while waiting for an upturn in the market. The US phosphate industry consolidation into three or four major companies should evolve into a stronger world market force.

Jan 1, 1993

By L. P. James

The Bulagidun copper-gold system occurs in Tertiary andesitic volcanic rocks. It is located (figure 1, from Curless, 1991) ca. two days walk from the coast in an isolated area on the northerly slope of the main range of mountains, in steep terrain dissected by erosion. Detailed and district-scale exploration from 1988 to 1991 by BHP Minerals defined a small, sub-economic resource of gold and copper. One preliminary estimate of the resource in bedrock suggests 14.4 million tons at 0.68 grams / Tonne Au and 0.61% Cu, in multiple small bodies.

Jan 1, 1993

By Charles L. Kimbell

While the statistical summary focuses on 1991 data, this update and outlook section draws on information available to the author as of the date of final preparation in early 1993. For all the press notoriety associated with the shift in the Near East crisis from the defensive posture of Desert Shield to the restoration of Kuwaiti sovereignty through Desert Storm, this was not the dominant event governing global economic thinking in 1991 and the first half and more of 1992. From the global perspective, the momentous political changes in the area that was the U.S.S.R. and in the smaller emerging transitional economy states of Eastern Europe will have even greater current and long-lasting effects on world mineral industry activities than the crisis in the Near East.

Jan 1, 1993

By Plamer D. J, Newman O. M G

The Effluent Treatment System at Pasminco Metals - EZ (PMEZ) was commissioned in December, 1991 and has operated satisfactorily, ensuring that aqueous discharges from PMEZ comply with the Tasmanian Environment Protection Act. The system treats both spills and run-off from the Zinc Plant, and acidic liquor generated in the gas cleaning section of the Sulphuric Acid Plant. The spills and run-off from the Zinc Plant are collected in a large catchment pond. The pond liquor, after partial neutralisation with sodium hydroxide to pH 4, and removal of suspended solids, is preferentially recycled to the Zinc Plant, for example, for washing of residues. Liquor which cannot be recycled, is treated in the Lime Neutralisation Section. The other input to the Lime Neutralisation Section is the acidic liquor from the Sulphuric Acid Plant from which mercury has been removed by contact with aluminium pellets in a fluidised column. In the Lime Neutralisation Section, the liquors are blended and neutralised to pH 10 by the addition of slaked lime. The heavy metals and most of the fluorine are precipitated. The precipitated solids are removed in a thickener with part of the thickener underflow being filtered. Most of the thickener underflow is recycled to generate solids that settle rapidly and filter well. The filter cake is returned to the Zinc Plant for the recovery of contained heavy metals while the thickener overflow is discharged to the Derwent River.

Jan 1, 1993

By M. C. Williams, T. P. Meloy

With the increasing power of computers to simulate and control processes in the mineral industry, predicting the potential use of computers in the minerals field is not a hazardous enterprise, but predicting the timing of their use is. Like the railroad industry, technology invades the mineral industry, rather than being an industry like electronics that creates technology. Because of this invasive nature of computer technology in the minerals field, this paper predicts what will be possible to do effectively and economically with computers in the mineral industry. Moreover, this paper explores the problems of using the emerging computer technology in the mineral industry. For example, if not now, it soon will be possible to control the output of a mineral processing circuit - high grade, high flow or a mixture of it - to meet the daily market conditions and to sell each day that daily "mill" output as "mill" futures on the commodity market. Finally, suggestions are made which may be done to prepare the industry for the computer revolution in the mineral industry.

Jan 1, 1993

By Farrelly C. T

The Wiluna mining operations are centred near the township of Wiluna 750 kilometres north-east of Perth and 600 kilometres east of Geraldton.The Wiluna gold mines produced over two million ounces of gold, predominantly by roasting the refractory sulphide ores, before closing in 1947. In the period 1984 to 1992, 668 000 ounces of gold has been produced from free milling oxide ores and the retreatment of tailing. A plant capable of treating the refractory sulphide ores using the bacterial oxidation, Biox technique was commissioned in March, 1993.The Wiluna lode deposits are hosted by a sequence of very low grade metamorphosed mafic flows at the northern end of the Norseman-Wiluna greenstone belt. A strike slip fault system provided conduits for fluid migration; ore deposition occurred at favourable sites along the faults. Satellite mines at Gourdis and Wiluna South provide laterite and lode style oxide ores.The different styles of deposit and ore types at the Wiluna mining operations require a flexible approach to resource estimation and grade control practices.

Jan 1, 1993

By Jay A. Bowden

In April of 1990, Homestake Mining Company began a 5,100 m (16,700 ft.) exploration drift from the Homestake Mine in Lead, South Dakota. The drift starts from the mine's 6800 level, nearly 2,100 m below the surface, and extends north to further explore occurrences of gold discovered by surface drilling. Access to the North Drift for men and materials and for disposal of waste rock is limited to the Homestake Mine's #6 Winze, which serves as the major production shaft for the deep levels of the mine. This paper will discuss the successes and challenges encountered while managing a tunneling project 2,100 m below the surface and from an active mine.

Jan 1, 1993

By Susan W. Campbell, Bruce Regensburg

"The CIM Careers Task Force has addressed industry's concern of a perceived shortage of skilled personnel over the coming decade. The industry is faced with a fundamental shift by young Canadians away from scientific and engineering careers, coupled with the fact that today 's students know little about the minerals industry and have a poor image of it.The responses to two questionnaires which were distributed to CIM members, government, professional associations, and educational institutions, formed the backbone of the Task Force position paper, which presents a shopping list of ideas and initiatives for consideration and to facilitation by the various organizations concerned.Tackling the image of the minerals industry is part of the answer to the careers crisis. On the positive side, the minerals industry provides the allure of a treasure hunt for young people and is seen as a significant contributor to the economy. It is understood to be well paying, provide good opportunities for advancement, individualism, and travel, and to be rich in esprit de corps. Enhancement of these positive aspects of the image can take place at all student age levels.Numerous initiatives tackle the negative aspects of the image. Young people perceive the industry to be environmentally damaging, which is the most crucial aspect that needs to be addressed. The industry is seen as still in the pick-and-shovel days and as a sunset industry that is running out of ore. Work in the minerals industry is perceived as dangerous and lacking glamour. And finally, the perceived remoteness of operations and exploration is seen as a drawback to a largely urbanized student group.Tackling young peoples' curiosity and interest in the minerals industry throughout grade school and encouraging postsecondary science and engineering students to enter the minerals industry by ensuring summer employment is the second part of the equation.The CIM Careers Task Force position paper develops strategy to attract and maintain interest of students in grade school, junior high, senior high school, and in post-secondary levels. The strategy outlines initiatives targetted at each of the educational levels and action plans to accomplish the objectives."

Jan 1, 1993

By Chen J, Zhu D

A detailed study on oil agglomeration of fine metal oxide particles is presented in this paper. The major content embraces several aspects which may possibly reflect the current trends in oil agglomeration such as the effect of chemical and physical parameters, the activation of target minerals and the deactivation of gangue particles, the mechanisim of bridging liquid and the kinetics of oil agglomeration process. Systems of ilmenite-feldspar, manganese dioxide - quartz were seperated successfully through oil agglomeration followed by decantation or flotation technique respectively. A triple mixture of vandium-bearing titanomagnetite ilmenite and feldspar was processed satisfactorily using a composite technology: oil agglomeration-decantation-magnetic concentration.

Jan 1, 1993

By D. R. Lanners

Samples of the same coal measure overburden spoil were obtained from three different mine sites. Site A used a 27-m3 tub-mounted dragline, Site S used a front-end loader and truck combination, and Site C used a 6-m3 crawler-mounted dragline. The spoils were analyzed in the laboratory for the strength parameters using drained triaxial tests conducted on 150-mm diameter specimens. Regression analysis was utilized to determine the appropriate failure criterion for the strength data from each site. Spoil obtained from Site S yielded higher shear strengths than Sites A and C.

Jan 1, 1993

By E. Bloomstein

The Lone Tree gold mine is located about 4S kilometers east from Winnemucca on the west flank of Lone Tree Hill in Humboldt County, Nevada. The deposit occurs at the north end of the low, rolling Havallah Hills and is about 1 kilometer south of Interstate Highway 80, in sections 11 and 14, Township 34 North, Range 42 East, Mount Diablo Base and Meridian (Fig. 1). The Lone Tree deposit is outside of any previously established mining district and all lands are owned or controlled by Santa Fe Pacific Gold or affiliated companies.

Jan 1, 1993

By K. N. Han, P. B. Queneau, A. Stojsic, M. J. Collins, V. J. Ketcham, R. M. G. S. Berezowsky, W. D. Vardill

The bulk of the ore found in the Lihir Island deposit is refractory in nature, with the gold contained in auriferous pyrite. In support of an evaluation of the development of this deposit by Kennecott (a wholly owned subsidiary of RTZ) and Niugini Mining Ltd., testwork has been carried out at the Sherritt Research Centre to demonstrate the amenability of the Lihir ore to pressure oxidation pretreatment to liberate the refractory gold. The results of pilot plant treatment of the Lihir ore in a continuous circuit with a feed rate of between 10 and 30 kg/h ore are described. The integrated circuit comprised pressure oxidation, residue washing, and gold recovery from the washed residue by carbon in leach or carbon in pulp cyanide leaching. Significant factors affecting gold recovery included temperature and retention time in the pressure oxidation step, and the concentration of soluble chloride in the feed. Gold extraction from well washed ore, after oxidation at 210°C for 66 minutes in the autoclave, was typically between 94 and 96%, compared with less than 30% by direct cyanidation.

Jan 1, 1993

By Morandini AF, Occella E, Clerici C, Mancini R

This contribution presents the first results of an experimental research aimed at finding an unified description of the first stages of a rock comminution process. With reference to the case of the jaw crushers and to the specific subject of the comminution law, the tests reviewed and analysed in this contribution have been carried out, at a laboratory scale, on five different materials (limestones, quartzite, serpentinite) at different reduction ratios and feed rates, and accurately recording both total power and idle running power. The analysis of the results has shown that: ò the grain size distribution of the products complies with a modified form of the Rosin-Rammler equation, already found to be well suited to representing the grain size distribution of blasted rock in previous works by the authors; ò observed trends of the consumed power at increasing reduction ratios is steeper than predicted by the classical Rittinger, Kick and Bond laws, Rittinger law representing however a closer approximation of the experimental results; and ò a more accurate description of the experimental results is provided by a modified form of the Rittinger law. Accuracy of the semi-empirical expression has been found to be usually better than ten per cent by comparing actual results with expected Results.

Jan 1, 1993

By Koppe J. C

This study presents the procedure of mine modelling and reserve evaluation by means of statistics, computer interpolation methods and aerophotography interpretation. All data are from Carbonifera Treviso, Laura Muller City, Santa Catarina State, southernmost Brazil. From 22 bore holes and nine trenches opened in the coal seam outcrops, a data base including level references and thickness of all rock formations was created.Using this information, basic statistic analysis was carried out, showing that there are three different populations (three modal distribution). These populations defined three geological blocks with different characteristics of overburden removal and mining methodology. This mathematical approach for analysing geological data is very important for correct mine planning and complementary prospection.

Jan 1, 1993

By Wayne N. McKee, Scott A. Lewis

"Introduction to the Syncrude OperationSyncrude Canada Ltd., located 42 km north of the city of Fort McMurray, Alberta, (Fig. I) is an integrated operation that has produced synthetic crude oil from the Athabasca oil sand deposit since 1978.The operation, consisting of a surface mine, an extraction plant, a bitumen upgrader, and a utilities plant, is currently capable of producing over 60 million barrels of crude oil per year. Production is expected to increase to 70 million barrels of crude oil per year over the next five-year period with no major changes to equipment or process planned.The Syncrude surface mine, producing a total of 675 000 tonnes of ore and waste per day, rates as one of the largest mines in the world. A strip mining method is utilized, with two or three operating benches necessary to excavate a total depth varying between 60 m and 70 m. The 20 m to 30 m of overburden is removed by electric and hydraulic shovels and 200-ton haul trucks, and dumped in the mined-out pit for final storage. The overburden operation creates a flat bench near the top of the ore zone on which the four 60 m3 draglines operate. The draglines excavate interbanded ore and waste in the highwall, with ore placed on the operating bench in windrows, and waste returned to the mined-out pit. The windrowed ore is reclaimed by four bucketwheel reclaimers, and discharged onto a conveyor system for transfer to the extraction plant."

Jan 1, 1993

By J. M. Manka

American mining companies operate many drum hoists, hoisting from varying depths with varying payloads. This paper reviews the procedure for selecting optimum wire rope constructions for existing hoisting installations. Selection for proposed installations, along with recommended hoisting parameters, is also discussed. To achieve optimum rope performance, preventive and corrective maintenance procedures are required and are reviewed here, along with examples of rope problems and their causes.

Jan 1, 1993