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By Gary A. Perry

Cyprus Sierrita produces copper and molybdenum from its Sierrita and Twin Buttes open pit mines south of Tucson, AZ. Both pits were started in the late 1960s and are more than 460 m (1500 ft) deep. Sierrita has used a Caterpillar 992C Remote Controlled Loader since January 1993. The loader was justified to increase safety and profits at Sierrita. It has exceeded all expectations. As of June 1993, the 992C had produced additional profits of more than $1.5 million. Safety and Geotechnical The safety of Cyprus personnel and equipment is always of prime concern. The remote controlled loader removes personnel from the active raveling area. But it requires prudent operation. The remote controlled loader discussed here is always intended to be used in a safe manner under a managed slope. Any increase in slope angle or use of any equipment under a critical slope is taken only after careful analysis of the specific

Jan 1, 1994

By Alex Ruzycki

Gold Fields-Mesquite is a 7.5 million ton per year heap leach operation located in the Maj ave Desert of Southeastern California. Extraction of gold is carried out on multiple lifts, with over 33.3 million tons of ore leached since the inception of operations in 1985. The delineation of the gold left in heap residue is a formidable task. Gold removed from active leach areas can be routinely monitored through sampling of emerging solutions but exact recoveries from specific heaps remains nebulous due to factors such as cross flow between sections buffering effects from multiple lifts, and releaching. In order to better quantify ultimate heap recoveries and increase releach efficiency, Mesquite initiated a residue drilling program. The project progressed through an evaluation of sampling protocol, drilling of residue by reverse circulation, entry of assays into a software package capable of producing grade-based contour maps, and a production scale releach test that evaluated the system's ability to predict residue grade.

Jan 1, 1992

By Michael N. Allenby

One of the least discussed areas in the ever-improving technologies of gold recovery from ore bodies and tailings is the chemistry of the waters used in the plants. Carbon-in­ pulp, carbon-in-leach, heap/dump leaching and iological oxidation processes are all affected by water quality. The remoteness of a lot of the plants means that the large water requirements can often only be met by a ground water source. The chemistry of waters from different sources poses different problems, but generally a lot of these waters are scale forming. Scale-forming tendencies can be described by calcium, magnesium, barium and strontium assays. They can be notated by Langelier and Ryznar indices. They can be plotted by computer programmes that print out scaling indices at different conditions. The propensity to scale can -be readily determined. The prevention of scaling -or at worst minimisation of scaling -is the ambition of the suppliers of scale inhibition programmes. This prevention/minimisation technology is discussed below.

Jan 1, 1993

By Z. Kowalski

Landfilling of waste causes the degradation of natural environment, not only due to land occupation, but also due to pollution of air, water and soil. The flotation waste from zinc-lead industry also poses such problem. There is a need to find the way to utilise substantial amount of these wastes and backfilling seems to be a good solution. Recently, in Poland only sand was used for backfilling. However, it will be more beneficial to substitute the sand with the industrial solid waste, especially flotation waste. The tests were performed in the laboratory to examine the use of flotation waste as a main ingredient for backfilling. The use of flotation waste is possible only when it is combined with other waste with specific bonding properties, especially regarding the prevention of leakage. The outcome of tests shows that flotation waste combined with cement and fly ashes can be used as a backfilling material. This paper presents the preparation of flotation waste for using it for backfilling.

Jan 1, 2006

By A. Dan Rovig, C. Kevin McArthur

Technical and managerial innovations in the minerals industry have allowed continuing mining activities in the United States, and elsewhere, as gold orebody quality has diminished or has become more refractory. Of course, world markets, permitting requirements, and political processes also have created a need for innovative practices that contribute to the survival of the mineral industry. The gold industry has been transformed, during the past approximately 40 years, from a predominantly underground mining and milling type of exploitation and extraction to the large-scale, relatively low-grade type of extraction that is common in the United States today. Indeed, with the introduction of gold heap-leaching technology and the development of mines that produce from large, relatively low-grade gold orebodies in the western United States, a "new" industry was born and continues to prosper today. It is worthwhile noting, however, that Dobra (1997) has reported that one of the major trends in the North American gold industry is a movement back toward underground developments.

Jan 1, 1998

By M. Cambridge

The extractive industries are currently, and will continue to be, major contributors to the world economy, particularly in the developing world where economic growth is dependent upon a sound supply of primary materials. However, tailings dam and other mine failures have been very much a feature of recent anti-mining publicity, particularly in Europe, and thus instrumental in inhibiting new mine developments. Although, superficially, the record of dangerous incidents might support the anti-mining position, closer inspection suggests otherwise. This paper reviews the failures which have occurred over the last 50 years and demonstrates that, though poor practice is an ongoing problem for the industry, the record is one of improvement in both design and practice. Examples are provided of significant events which have led to dramatic advances in design and operation. The paper assesses the improvements made in technology and practice, and concludes that historic events must continue to form the underlying basis for design and operation of future mining projects.

Jan 1, 2005

By S. K. Kawatra, S. J. Ripke

Finely disseminated iron ores compose much of today's reserves. After removing the silicate gangue, the resulting fine iron oxide concentrates require pelletization with a binder to enable transportation and reduction. Binders can be used more efficiently if their binding mechanisms can be completely understood. Typically, bentonite clay is needed as a binder to improve the strength of the pellets. Bentonite is an effective binder at a relatively low cost, but costs could be reduced further by replacing bentonite with even lower-cost binders, such as high-carbon Fly-Ash Based Binder (FBB). In this study, it was found that bentonite binds by a physical mechanism, while FBB binds by a chemical mechanism. These mechanisms were determined to be incompatible. Partial replacement of either binder with the other reduced dry magnetite pellet compressive strengths below the industrially acceptable value of 22.2 newtons (5 lbf). Activators and accelerators that activated the fly-ash deactivated the bentonite. The incompatibility of these two binders is explained.

Jan 1, 2000

By N. Roqueñí, J. Loredo, F. Pendás

Impacts of mining on surface water and groundwater occur frequently not only in active mines but in abandoned mines, then the establishment of effective legal mechanisms for the regulation and control of mine waters is a necessary step in order to avoid pollution from mine waters and in consequence to contribute for a sustainable development of the mining industry. Currently there is a lack of a specific European legislation about mine waters and this absence of legislation occurs too at national level in many European countries. This absence of an European specific regulatory framework for mine water pollution questions the effectiveness and the applicability of the current legislation and this fact has led the EC to put forward proposals legislation to adequately deal with environmental and social consequences of mining, and among those proposals is a draft for a directive on waste from the extractive industry that includes provisions for mine water pollution.

Jan 1, 2005

By S. L. Bessinger

The need for improved safety and productivity brought about the introduction of longwall mining to the Appalachian coal fields. These same forces continue to drive developments in modern longwall equipment and mining practices. Current initiatives to improve productivity and safety are focused on automation and the effects of scale in equipment design. Longwall roof-supports, shearers and face-conveyors have changed significantly. Panel layouts have evolved to include larger total tonnages and provide for more rapid development of gate-entries. These advancements have improved longwall productivity and new production records are continually being set. Roof supports Reliability is implicit in the quest for automation. It is impossible to automate equipment if it is not reliable. To a large degree, this has been the problem with longwall shield automation efforts. The "electronic control" of shields depends on the proper functioning of electronic equipment, electrohydraulic valves and full-flow service valves onboard every support.

Jan 1, 1995

By Jack G. Pippenger

The Coteau Properties Co.'s Freedom Mine is a surface lignite mine that uses large draglines, trucks and shovels, tractor-scrapers and bulldozers to uncover a single coal seam. In 1989, a work order system was instituted to record data by equipment type, cost, productivity and distance. The system was also used to provide historical information to plan the most efficient and economic use of each equipment type in the mining operation. The Coteau Properties Co. is a wholly owned subsidiary of The North American Coal Corp. The company was formed in 1972 to supply lignite from its Beulah-Hazen coal reserve to a coal gasification project and an electrical generating facility located near Beulah, ND. The reserve consists of a single coal seam between 3 and 7 m (10 to 23 ft) thick. The overburden above the coal is predominately glacial tills and clays and ranges from 6 m (20 ft) to more than 60 m (200 ft) thick.

Jan 1, 1994

By Richard L. Bullock

The hard rock mining industry has long envied its counterparts in underground mining of evaporites, coal and soft iron ore, who have made great strides in productivity using mechanical excavators. Continuous mining machines produce large tonnages in Canadian potash mines and in modern longwall coal mines. Hard rock is defined here as having an unconfined compressive strength (UCS) of more than 124 MPa (18,000 psi). Silica content, rock quality designation (RQD) and fractures affect the ability of mechanical tools to excavate rock, but the UCS is the main factor. Much research and development work has been devoted to continuous mechanical mining of hard rock, and the technology continues to improve. A few commercial applications have been reported. The development process has been slow and costly, but the outlook for the technology has never been more promising. The current state-of-the-art of continuous, mechanized underground mining technology is reviewed here, with examples of commercial applications that have been tried in recent years.

Jan 1, 1994

By T. Hudaverdi

Airblast, the focus of the paper, is defined as blast induced atmospheric pressure waves. High overpressure levels may cause breaks of windowpanes, and plaster cracks. Additionally many mines come across psychological responses of residential areas. In this paper the monitoring of air blast is explained and evaluation procedures are defined. The allowable limits of the air blast are presented. The scaled distance approach developed for the prediction of airblast is explained. For the very rapidly growing cities, like Istanbul, the required raw materials for the construction industry are supplied from quarries in the vicinity or from inside of the city. With further growth of the population density, many quarries approach suburban areas and it will be more important to minimize the adverse effect of the blasting operations in the near future. In this paper the airblast levels that monitored in Cendere Region Quarries near Istanbul are presented. The suggestions put forward to control airblast levels.

Jan 1, 2006

By G. Trusler, P. Dama, C. Buckley, C. Jänisch

In the 1990s, Cleaner Production (CP) approaches were successfully introduced to a number of industrial sectors in South Africa. Building on this success, the South African Water Research Commission has commissioned a 3-year study to investigate the use of CP and its related set of environmental assessment and management tools in the mining industry. A scoping study is being carried out on the current knowledge of CP approaches being used in the industry, as well as the proactive and preventative measures being undertaken. One of the significant findings of the scoping study is that distinct differences exist between the larger global companies and the smaller local companies. Being a water research project a key focus area of the project is to reduce the impacts related to mining on the South African water resources. Some of the significant water related threats identified include acid mine drainage, the shortage of the resource and the effects of inter-mine flow.

Jan 1, 2005

By Richard A. Hunnisett

Silica sand is one of the world's most plentiful resources and is a basic necessity in our way of life. The end uses of silica sand are an integral part of our homes, transportation, and places of work. The environmental legislation enacted in the early 1970's, coupled with the oil embargo and higher than normal inflation, have had a very real impact on the industry and its primary consumers, the foundries and glass producers. The present environmental laws directed at air and water pollution and the working environment can, in most cases, be met, but not without large capital expenditures for equipment. These expenditures must reduce the funds available for expansion and modernization of existing processes which are necessary if the costs to produce industrial sand are to remain at acceptable levels. The concern for the future is the enactment of more stringent laws, and the available technology and equipment to economically comply with them.

Jan 1, 1978

By Tench C. Page

The Yarnell gold deposit is located 1.5 km (1 mile) south of Yarnell in the Weaver mining district of Yavapai County, AZ (Fig. 1). Elevations within the area of the deposit range from 1400 to 1560 m (4590 to 5120 ft). Historic production, principally from quartz veins localized along the Yarnell fault, was about 200 kt (220,000 st) at an average grade of 6.9 to 10.3 g/t (0.2 to 0.3 oz/st) gold. The federal government closed the mine in 1942 due to World War II. Norgold Resources Inc. leased the property in 1988 and joint ventured it with Asarco the same year. Asarco drilled 7822 m (25,660 ft) in 96 reverse circulation and four diamond drill holes and identified 8 t (260,000 oz) gold reserve. IBema Gold Inc. acquired Norgold in 1991 and is currently permitting the project. Production is expected to begin within the next two years

Jan 1, 1994

By Jean Dupéré

Introduction Before examining the current position of the asbestos industry and its market outlook, it is important to describe the product itself. If we are to understand the problems besetting this basic mining and manufacturing industry, and, more importantly, if we are to appreciate solutions to these problems, we had better view asbestos from the proper perspective. Asbestos has a unique combination of properties - properties not found in any other natural substance or man-made material. As a result, asbestos has found its way - in fact, is welcomed - into hundreds of applications. Properties and Products World production capacity of asbestos fiber is about 6.5 Mt (7.2 million st). Major producers and their approximate percentage share of actual production are: USSR, 47%; Canada, 24%; South Africa, 5%; Zimbabwe, 5%; Brazil, 4%; Italy, 3%; and others (including the US, China, and Greece), 12%. Although Canada accounts for less than one-third of the world's

Jan 7, 1984

By P. Anciaux, T. Simpson

The competitiveness of the EU manufacturing industry has come to the forefront of EU politics. The systematic monitoring of developments and the review of the state of the competitiveness of economies and enterprises was identified as an essential component in this process. Work is currently being carried out within Enterprise and Industry Directorate-General in order to analyse the different factors that influence the competitiveness of the non-energy extractive industry. Such an assessment should help to identify policies and actions which could contribute to and enhance the competitiveness of the industry. Assessing the competitiveness and sustainability of the industry implies the need for reliable, consistent data. One important example of how this need is being addressed, is the development of sustainable development indicators (SDI) for the EU non-energy extractive industry. These seek to monitor the industry’s performance and provide a platform for openness and discussion. Work was started on the development of SDIs in 2000, and the first report was published in February 2004.

Jan 1, 2005

By B. Das, D. D. Mishra, M. I. Ansari

Experiments conducted with a 75-mm-diem hydroryclone have shown it is possible to obtain an iron ore concentrate containing 60% Fe. 2.65% SiO2, and 4.0% Al2O3 from Barsua iron-ore washing-plant slimes. About 60% of the iron values are recovered from slimes containing approximately 49% Fe, 8.9% A1203 and 11% SiO2. The obtained products can be used in the sinter feed for iron and steel making. The key to achieving process success lies in establishing the correct cut point (d50) of the hydrocyclone through the manipulation of operating and design variables, such as spigot and vortex finder diameter, solids concentration and operating pressure. The cyclone efficiency is represented by the partition curve. The cyclone performance, evaluated mathematically from the reduced efficiency curve, is represented by the equation Y = 100[1 -exp(-axb)], where: •X = did 50, •Y = corrected of efficiency (%) and •a and b are constants.

Jan 1, 1994

By S. S. Hsieh

As part of a program to address the long-term need to ensure adequate supplies of domestic phosphate raw materials, the Tennessee Valley Authority (TVA) has conducted considerable research on dolomitic phosphate rock beneficiation. The discovery that alkyl diphosphonic acids act as phosphate mineral depressants led to the development of several processes involving a carbonate flotation step for the effective beneficiation of these problem ores. Most recently, a partial deoiling process in which the reagent consumption is greatly reduced has been developed. The reduction is achieved because part of the initial feed is beneficiated without passing through the separate carbonate flotation step. Using this method, a phosphate product containing 30.6-30.9% P2O5 and 0.7-0.8% MgO was obtained from a Florida dolomitic phosphate pebble that contained about 23% P2O5 and 2.0% MgO. The P205 recovery was 80.8-86.5%.

Jan 1, 1991

By S. Constantinescu

The alloys mainly used for short (or segmented) chip material cutting (cast iron, porcelain, etc) are alloys of the WC-Co type; in some cases with small additions of other carbons. The same alloys but of different granulometric classes are also used for pieces exposed to wear (wire drawing, moulds) The higher performance of the WC-Co alloys in chip machining applications is accounted for by their very good heat conductivity, which is 2-3 times higher than that of fast steels. The hard-alloys producers can resort to a wide range of possibilities to achieve variation of properties of a WC-Co composition and thus they can adapt their products to the particular type of tools they may choose to manufacture. The present metallography technique allows for a correct identification and evaluation of hard sintered carbons structures. The metallography approach is an indispensable method of investigation and control in the industry.

Jan 1, 2008