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Case 1: A driller raised a drill rig mast into a 7200-volt overhead power line. Both he and his helper were killed. Case 2: A driller-helper was pulling a winch cable toward a stack of drill steel when the cable contacted a 12,000-volt power line. The helper was killed, and the driller at the rig controls was severely injured. [ ]

Jan 1, 2006

Predicting Water Recovery from Flotation Cells

Sep 13, 2010

By J. Crummy, I. K. Anderson, A. J. Hall, R. S. Haszeldine

Bedrock gold mineralisation has been located in association with an extensive float train 25 km west of known alluvial gold. It is in the form of open, matrix-supported breccias comprising pyritic quartz/sericite clasts in a vuggy, cherty chalcedonic and crystalline quartz matrix. Fluid inclusions in pyritic clasts indicate trapping temperatures for gold mineralising hydrothermal fluid of 170-240 degrees C. This mineralisation could represent the upper part of a feeder zone to an exhalative hydrothermal system. It is possible that other high-level feeder zones could be preserved elsewhere in the area. Deep weathering of such a system could provide a source for the alluvial gold localities near Helmsdale. It is suggested that east and central Sutherland presents good prospects for exhalative epithermal gold mineralisation and the associated feeder zones

Jun 19, 1905

By Michel Ruel

"PID loops – also known as base layers or regulatory controls – form the foundation of any plant’s control layer and it is generally accepted that PID loop health has a direct impact on the plant’s bottom line. Keeping these thousands of control loops in good health has a direct impact on the plant’s bottom line: it reduces variability, improves quality and throughput, and decreases energy costs and raw material usage. This has been well proven and documented in many articles. In the last ten years, technology has evolved: control engineers can now keep track of control loop performance and link it to the root causes of variability. However, they lack industry-wide best practices and criteria for determining what can be considered as excellent, good, fair, or poor performance. To ensure that PID control loops continue to perform well and meet their objectives, control engineers need a combination of (a) an appropriate monitoring technology and (b) best practices for doing the maintenance of base layer controls.Most plants have limited resources and operate with an increasing number of constraints; therefore, using the right tools and including reports in daily workflow is key for success. This paper suggests roles and responsibilities of key players needed to work toward control performance best practices and discuss organisational changes to succeed.INTRODUCTIONAlthough PID controllers are reliable workhorses in the process industry, they are often underrated. Since the 1980’s, computer control has evolved and the control algorithms used by control engineers have become increasingly complex. However, PID controllers still handle over 90% of the control loops in operating plants. Table 1 shows the savings that can be realized by achieving best-practice in several different process control categories (Brisk, 2004). The savings are expressed as a percentage of production costs."

Jan 1, 2011

By K. V. Konigsmann

"Mattagami Lake Mines Ltd operate a zinc-copper mine with an annual output of about 200,000 tons of zinc and 30,000 tons of copper concentrates. Zinc concentrates arc shipped to a company owned smelter in Valleyfield (a distance of 690 miles), for Export to Quebec City and also to Josephtown, Pennsylvania (1,060 miles, Figure 1.)The protection of concentrates in open gondola rail shipments has been a matter of concern since operations commenced. Considerable financial losses did occur at times because of wind erosion. Operating difficulties were also encountered by customers because of excessive moisture accummulation in the concentrates. Test shipments made in 1969 established the magnitude of losses in open cars. The results and subsequent investigations at our mines and elsewhere confirmed that load protection is an economic necessity.Many types of covers were experimented with, more or less successfully. In 1972 we agreed on a joint program with Dupont of Canada Limited. A new type of cover was developed by early 1973. It has been in use since, undergoing several improvements as experience accumulates."

Jan 1, 1975

By O. Acaroglu

Selection of the most suitable roadheaders (boom type tunnelling machines) for the galleries/tunnels to be excavated in certain rock and under known project conditions is important for avoiding problems during application. This research utilized a multiple attribute decision-making method and studied how this will be applied for the selection of boom-type excavation machines. The Cayirhan Coal Basin was used for selecting roadheaders using the analytical hierarchy process, which is one of the multiple attribute decision-making methods. To conclude, this study reveals that decision-making methods can be used in the process of selecting roadheaders for the excavation of galleries. Keywords: roadheaders, multiple attribute decision-making, analytical hierarchy process.

Jan 1, 2006

This chapter summarizes data on crude nonfuel mineral production for the United States, its island possessions, and the Commonwealth of Puerto Rico. Also included are tables that show the principal nonfuel mineral commodities exported from and imported into the United States and that compare world and U.S. mineral production. The detailed data from which these tables were derived are contained in the individual commodity chapters of Volume I and in the State chapters of Volume II of this edition of the Minerals Yearbook. Although crude mineral production may be measured at any of several stages of extraction and processing, the stage of measurement used in this chapter is what is normally termed "mine output." It usually refers to minerals or ores in the form in which they are first extracted from the ground, but customarily includes the output from auxiliary processing at or near the mines.

Jan 1, 1988

By Allan A. Este, Bruce Arthur

"Rio Algom's Stanleigh Mine and Mill Operation Was' officially started up in August 1983. In September 1982, Rio Algom contracted Estonix International Inc. from Lively, Ontario, to develop and implement two innovative programs: (1) Work Renovation Planning, and (2) Systems Performance Training. This paper deals with the development and implementation of these two concepts relative to the plants technology from start-up to present and the exceptional results achieved. This paper discusses how a small but motivated workforce resulted in the smooth transition from startup to full production. It also deals with how these concepts were applied elsewhere in the organization which permitted a successful transition and downsizing of the over-all operation.IntroductionRio Algom Limited produces uranium in Elliot Lake, Ontario. In the late 1970s Rio Algom entered a contract with Ontario Hydro to supply uranium from its Stanleigh property, which had been idle since 1960. The mine was subsequently upgraded, and a new modem mill was designed and built, commencing operation in 1983.From then until September 1990,Rio Algom had three producing mines and mills in the Elliot Lake area. Quirke mill, with a capacity of 6350 tonnes per day, operated continuously from 1968. The Panel mill with a 3000 tonnes per day capacity, operated since 1979. Stanleigh mill continues to operate under long-term contracts, although at a production rate about 25070 lower than its rated capacity of 5000 tonnes per day.Both the Quirke and Panel mills, although not entirely similar, were conventional uranium mills utilizing crushing, grinding, leaching and ion exchange. As such, and in keeping with the traditional management style, there was a rather large mill operating workforce, which utilized a line-of-progression job classification system."

Jan 1, 1993

Mechanism of Modified Sodium Silicate on Fluorite Ore Flotation

Sep 13, 2010

By Richard R. Brochu

At the International Society ofExplosives Engineers Annual Conference held in Nashville, Tennessee in February 1995, a Seismograph Standards Committee was established. The purpose of this wmmittee was to develop objective performance specifications for vibration measurement instrumentation and field use practices. It was also understood that due to geology, temperature, and moisture in the soils, it is not possible to design and build an instrument to give ‘results which are absolutely comparable for ground vibration. It was, however, considered essential to standardize instrumentation by which vibration can be measured under closely defined conditions so that results obtained by users of seismographs are always the same ,&thin stated tolerances.

Jan 1, 1998

By J. I. Mathis

"The failure that was utilized for developing this model was a double bench-scale failure, approximately 20 m in height, in the Misery pit at BHP Billiton’s EKATI mine site. The bench that failed was excavated in biotite schist. Due to previous problems with bench-scale toppling failures, this bench was excavated with a 70° inclined, 30 m deep preshear. Upon exposure, the wall was very clean with half-barrels commonly observed from the pre-shear operation.In August 2003, a bench failure of about 1000 t occurred in this pre-sheared biotite schist (Fig. 1). Upon examination it was noted that the foliation that paralleled and dipped at 70° into the face when excavated was approximately horizontal at the top of the failure (Fig. 2). While the failure mode itself appears complex, the failure was apparently driven by three factors:• a low-angle, low-frictional strength fault or discontinuity at the base of the failure area;• water either contributed meteorically from precipitation and/or from permafrost melt; and• foliation planes providing a viable toppling geometry once toe block motion began to occur.The above details are illustrated in Figure 3.After considerable thought and analysis, a model was postulated for the failure.It is thought that the entire failure had been triggered by displacement of a toe block (Fig. 4). This toe block is bounded on the back by foliation, the bottom by a low-angle, lowstrength fault, and the front by the bench face. Water pressures behind the bench face developed forces on the block as can be seen in Figure 5. These forces were sufficient to induce block motion. As can be seen in the relative shear strength diagram in Figure 6, only a small amount of water is necessary in the face to initiate block displacement. Note that in this figure, a simplistic piezometric pressure distribution was assumed."

Jan 1, 2004

By E. Chin

The only economically significant mineral exploited in Banglades - during 1981 was natural gas. Nitrogenous fertilizer production was important to the agricultural sector and was totally dependent on the natural gas for fuel and raw material. Domestic cement plants were also fu pled by natural gas. The flat river-delta terrain for most of Bangladesh makes the potential for discovering major mineral deposits poor. No large deposits of metal ores have been found and only in the small hilly southeastern section of the country is there even much chance of finding any. Heavy mineral sand deposits may eventually be exploited along the Chittagong coastline. There is a good potential for crude oil discoveries. The Bangladesh economy has been heavi¬ly subsidized by billions of dollars of foreign aid since the country's inception. A World Bank report recommended total aid needs of over $2.6 billion in fiscal year (FY) 1980-81. It received commitments for barely over one-half that amount.

Jan 1, 1983

By Marilyn Biviano

(l)The direct economic costs to this nation resulting from a decision to embargo South African strategic and critical minerals imports are estimated at $1.85 billion per year.2,3 About 94 percent of these estimated costs are for two platinum-group metals (PGM's), platinum and rhodium. The estimated costs of a 5-year embargo beginning in 1988 for the strategic and critical minerals analyzed are presented in Table 1.4 (2)There are sufficient alternative world sources to South Africa for manganese, chromium, palladium, titanium, and vanadium to meet U.S. industrial demand in the event of an embargo. (3)Alternative world sources to South Africa for platinum and rhodium cannot meet U.S. industrial demand. Non-South African world supply sources can meet about 40 percent of domestic platinum consumption requirements and 50 percent of rhodium requirements. (4)As a result of the increase in prices for platinum and rhodium during the embargo, expansion of domestic platinum-group metals mining and secondary production is expected. During a five year embargo, domestic primary and secondary production expand and together satisfy about one-third of U.S. platinum requirements, one-third of U.S. rhodium requirements, and over one-half of domestic palladium requirements.

Jan 1, 1988

By Louis E. Dalverny

U.S. Bureau of Mines research to develop diagnostic methods to locate and evaluate fires in abandoned mines and waste banks and techniques to extinguish such fires was applied to an abandoned 60-acre underground bituminous coal mine (Renton, Allegheny County, PA) to locate and extinguish three separated fire zones. Mine fire diagnostics interpret changes from baseline values in subsurface pressures, temperatures, and mine gas composition under imposed pressure gradients induced by a borehole exhaust fan. The effective gas sampling area surrounding each borehole is greatly enlarged. Sampling iterations, using a "communicating" boreholes set, provide "fire signature" information for locating both heated and cold areas. Time-dependent monitoring differentiates heating and cooling periods resulting from combustion front movement and/or fire extinguishment activities. A water injection with fume exhaustion extinguishment effort involved injecting water through boreholes to quench the heated zones while exhaust fans actively removed heated gases from the mine. The technique was ineffective as implemented, primarily because of inadequate spreading of water from the injection points. The Bureau's diagnostic method determined the fire locations and the effectiveness of the water injection with fume exhaustion extinguishment technique.

Jan 1, 2010

By Richard D. Smith

The Bureau of Mines evaluated the emission control methods, including the capital investments and operating cost, necessary for further reducing lead levels in ambient air at the Glover, Herculaneum, and Buick smelter-refineries in Missouri and the East Helena, MT, smelter. The U.S. Environmental Protection Agency (EPA) has proposed more stringent lead in ambient air standards than those currently in effect. This report presents theoretically achievable lead emission reductions and estimated capital and operating costs. Lead emission inventories theoretically can be reduced from 1985 levels by 2,421 lb/d at the three Missouri operations by containing and filtering fugitive emissions within structural enclosures and baghouses. The aggregated capital and operating costs in 1986 dollars using conventional environmental and workplace technologies are estimated to be $250,014,100 and $18,507,800, respectively. Estimated total incremental cost is $0.063/lb as refined lead. Additional regulatory costs attributable to Occupational Safety and Health Administration (OSKA), U.S. Department of Labor, workplace standards are included since proposed environmental controls may otherwise degrade workplace conditions. Continuous drossing is evaluated as an alternative to conventional OSHA controls. Substituting continuous drossing for conventional work- place technology results in an estimated aggregated capital and operating costs of $258,344,800 and $15,719,600, respectively. Estimated total incremental cost is $0.062/1b as refined lead. For comparison, the average open market price of refined lead during the first quarter of 1986 was $0.184/lb.

Jan 1, 1987

By P Wopereis

The Nokomai valley is located within the pumpellyite/actinolite facies of the Otago Schist, a regional scale metamorphic belt in Southern New Zealand. The Otago Schist is dominated by psammitic and pelitic greyschist with more subordinate greenschist, quartzite, marble, and ultramafics. Mining in the Nokomai, began in the 1860s, with sluicing of terrace gravels in the lower valley. Good gold is reported to have been won from unconformities within very weathered gravels lower in the terrace sequences, and particularly from within channels which dissect these older deposits. Gold was recovered from these terraces in the main Nokomai Valley, and two major tributaries (Victoria Gully and Bullock Head Creek). In the period 1885 - 1887 further gold was discovered in basal gravels beneath the Nokomai flats when the Hunter brothers sank two shafts and excavated a connecting drive to discover a lead 1.2 - 1.5 m thick. The Golden Lion Sluicing Company began mining in 1896 using an hydraulic elevator on the very 'tight' 1.8 - 2.4 m of basal gravels. This operation was followed by the Nokomai Gold Sluicing Company whose average return grade was >485 mglm3 until mining ceased in 1943 (Wopereis; 1988, 1989). A quartz vein, Commissioners Reef, was worked for small production at some time during the 1920 - 1930 period, until fault termination of the vein ceased production.

Jan 1, 1996

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Jan 1, 1938

By T Wootton

The Barrytown ilmenite pilot plant was commissioned in two stages using Westport Titanium Project heavy mineral concentrate. The wet concentrator was commissioned on the 17 December 1989 and produced magnetic concentrate from this date.   The Drymill was commissioned on the 27 January 1990 and produced product grade ilmenite successfully from the onset.   The commissioning period was exceptionally short by normal standards and few problems were encountered. This paper concludes with general observations of operations of the pilot plant.

Jan 1, 1990

The poor reconciliation between the values of estimated and actual grades can cause major economic losses to the mining industry. In a mining operation grade reconciliation is comparing the values of estimated grade calculated in exploration stage with actual grade obtained from blastholes' data. Many different factors affect the degree of reconciliation in a mining operation. In this paper we investigate the factors related to estimated grade which affects the reconciliation process in the exploration stage of the orebody. These factors are the sources of uncertainty in the rest of mine life. In this area the most important factors are inherent variability, statistical uncertainty and systematic uncertainty. A probabilistic model was presented to model each source of uncertainty. The implementation of proposed model was checked and its validity was investigated using real data in an iron open pit mine in Iran.

Dec 6, 2010

By C. L. Lin

The characterization of rare-earth resources in 3D is now possible using high-resolution X-ray microtomography (HRXMT) to describe ore texture and mineral phase composition. In addition, detailed texture analysis, including grain exposure and mineral association, can be described. Preliminary examination of a sample of Mountain Pass ore is reported to describe the spatial distribution of the mineral phases (calcite, barite and bastnaesite), particularly the grain size distribution of bastnaesite. The examination includes analysis of selected particle size classes to determine the appropriate size for liberation of the rare-earth mineral bastnaesite. Good liberation is expected to be achieved if the material is ground to a top size of -150 µm.