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By N. Aouad

The deployment of large machinery for low cost, bulk surface mine production operations has resulted in high-impact shovel loading operations (HISLO). In extreme cases, shovels load large dump trucks with 100-ton (or more) passes generating high-impact forces under gravity. HISLO generates high-frequency shockwaves that cause severe truck vibrations exposing operators to whole body vibrations (WBV). Current research study in this area has established that the vibration levels affecting the operator?s seat, lower-back, lumbar and cervical regions fall within the extremely uncomfortable zone compared to the ISO 2631 comfort zone. These results pose health threats to truck operators over long-term exposure to these vibrations. In this paper, the authors will examine engineered solutions to mitigate these health threats.

Jan 1, 2011

By R. Q. Honaker

Dense medium processes are used to clean over 50% of the coal that is fed into preparation plant facilities worldwide. The dense medium is formed using ultrafine magnetite which is recovered after the cleaning step using drain-and-rinse screens and magnetic separators. Despite the high efficiency of the recovery system, magnetite losses of around 0.5 to 1.0 kg/ton are common. Considering the recent escalation of magnetite to around $300/ton, an alternative source of magnetic material from coal combustion bottom ash has been investigated. A relatively low cost recovery system has been developed. Dense-medium tests using the bottom ash magnetics revealed a high level of efficiency as indicated by probable error values around 0.03 over the range of medium densities investigated. The results from both the recovery and coal cleaning efforts will be discussed in detail.

Jan 1, 2009

The 18th annual American Mining Hall of Fame Awards Banquet sponsored by the Mining Foundation of the Southwest will be held on Saturday, Dec. 2, 2000 at The Westin La Paloma in Tucson, AZ. The 2000 inductee, guest of honor and featured speaker at the banquet will be Ronald C. Cambre, chairman and chief executive officer of Newmont Mining. He will be honored for his role in positioning Newmont as an innovative and key player in the gold mining industry.

Jan 1, 2000

By Franz Walchshofer, Mark Kuchta, Nobuharu Isago, Ugur Ozbay, Wolfgang Dolsak

A series of in situ pull test were performed on a new design friction stabilizer bolt with the objective of determining its performance characteristics. The bolt is installed while drilling, thus improving safety and significantly reducing the installation time. An optional expansion element can be inserted into the bolt to provide an end-anchorage, which further increases the bolt’s capacity. In situ tests show that the pull capacity of the 2 m long new design bolt is about 15 tons. When installed with an expansion element, the pull capacity of these bolts becomes as high as 30 tons.

Jan 1, 2005

Editor?s note: Each year, Mining Engineering features an industrial minerals review. Several people put in a fair amount of time in developing the material for this issue, all the while doing their own jobs. Thank you to the industrial minerals annual review editor, to the Industrial Minerals and Aggregates Division technical committee chair and vice-chairs, and to the authors of the individual commodity profiles. Jim Norman, member SME, of Tetra Tech, is the industrial minerals annual review editor. Rajesh Raitani, member SME, of Cytec Industries Inc., is chair of the Industrial Minerals and Aggregates Division?s Technical Committee. The technical Committee vice chairs include: ? Vishal Gupta, member SME, of FlSmidth, Agricultural Materials. ? Candace Trimble, member SME, of Oil- Dri Corporation of America, and Bradley Van Gosen, of the U.S. Geological Survey, ceramics and refractory materials. ? Stanley Krukowski, member SME, of the Oklahoma Geological Survey, chemical raw materials. ? Russell Winn, member SME, of R.E. James Gravel Co., chemical raw materials. ? Justin Zdunczyk, member SME, of Plum Creek, construction materials. ? Jerry Gauntt, member SME, of Golder Associates, fillers and pigments. ? Michael Cheshire, member SME, of Los Alamos National Laboratory, sorbents, filters and process aids. ? Rajesh Raitani, member SME, of Cytec, Industries Inc., specialty minerals. Their help makes possible this June industrial minerals issue. On behalf of ME readers, the editors thank them.

Jul 1, 2013

By W. H. Langer

Large amounts of limestone fines coproduced during the processing of crushed limestone may be useful in the sequestration of carbon dioxide (CO2). Accelerated weathering of limestone (AWL) is proposed as a low-tech method to capture and sequester CO2 from fossil fuel-fired power plants and other point-sources such as cement manufacturing. AWL reactants are readily available, inexpensive, and environmentally benign. Waste CO2 is hydrated with water to produce carbonic acid, which then reacts with and is neutralized by limestone fines, thus converting CO2 gas to dissolved calcium bicarbonate. AWL waste products can be disposed of in the ocean. Feasibility requires access to an inexpensive source of limestone and to seawater, thus limiting AWL facilities within about 10 km of the coastline. The majority of U.S. coastal power generating facilities are within economical transport distance of limestone resources. AWL presents opportunities for collaborative efforts among the crushed stone industry, electrical utilities, cement manufactures, and research scientists.

Jan 1, 2009

By John Songstead

INTRODUCTION The Bunker Hill mine, located at Kellogg, ID, in the Coeur d'Alene mining district, has been a major pro¬ducer of lead-zinc-silver ore since 1887. Since its dis¬covery, it has produced over 25 401 171 t (28 million st) of ore from 20 to 25 veins and ore zones. The mine now covers an area of approximately 1.609 km (1 mile) in length and 0.8 km (1/2 mile) in width and extends from 1097 m (3600 ft) above sea level to 488 m (1600 ft) below sea level. Production is presently at a rate of 1542 t/d (1700 stpd). During 1965, a new stoping method, the Bunker Hill pillar system, was developed to enable the profitable mining of large, low-grade zinc ore bodies. The system was specifically designed to in¬corporate the Atlas Copco T26GH rubber-tired loaders. High productivities were achieved, and the method was adapted for mining the higher grade stopes where large timber square sets are utilized. This results in nearly 100% extraction. GEOLOGY The area encompassing the Bunker Hill mine lies immediately south of the Osburn fault, a major east-west striking, deep-seated strike slip fault which is the dominant structural feature in the Coeur d'Alene district. The Bunker Hill forms a series of veins and mineralized zones which occur as link structures, tension fractures, and breccia zones in folded, interbedded argillaceous quartzites of the Revett and St. Regis formations of the Precambrian belt series. The Rosco ore body is predominantly a zinc ore body above the Cate fault, which is presently known to occur from the 13 level. [elevation 488 m (1600 ft)] to the 1600 level [elevation 304 m (1000 ft) ]. These ore bodies are stringer zones with at least one dominant 1.8 to 4.5 m (6 to 15 ft) wide band of ore. They dip 0.09 to 0.26 rad (5° to 15°) steeper than the local 0.61 rad (35°) dip of the Cate fault, and also deviate 0.26 to 0.52 rad (15° to 30°) in strike from the Cate. Because of the flat dip and fractured weak hanging wall, normal cut-and-fill mining has not proven practical in this ore body. The mechanized timber methods described in the next section and the Bunker Hill pillar system are the mining methods successfully used. MINING METHODS While pillar stoping and mechanized cut-and-fill stop¬ing methods were obviously superior to the widely used timber stoping methods, as far as cost and productivity

Jan 1, 1982

By P. Sangurmath, C. Gundewar, M. Riyazulla, V. Vasudev, N. Shadaksharswami

Dharwar craton in the southern Indian shield, comprises the Neoarchaean foreland in the west and a relatively younger accretionary complex composed of granitoids and intervening gold-bearing volcano-sedimentary belts. The Hutti schist belt hosting a major gold producing mine is situated in the northern part of the eastern Dharwar craton. It is a horse-shoe shaped structure comprising predominantly of pillowed metabasalt of tholeiitic composition with minor amounts of clastic sediments and felsic volcanic rocks. The belt is intruded on all sides by circular to tabular bodies of granites and granodiorite. Important gold deposits are located at Hutti, Hira-Buddini and Uti villages. Felsic volcanics in the Hutti belt occur as tabular bodies of quartz porphyry and breccia. Two of the gold-bearing reefs in the Hutti mine, Viz., Middle and Strike reefs are intimately associated with tabular sub-vertical sheets of mylonitic quartz-feldspar porphyry intruding pillowed metrabasalt. In Uti mine area, the felsic volcanics occurs as a tabular body. At Hira-Buddini, the felsic volcanic occur as a irregularly shaped sheet in pillowed metabasalt. Mineralogical and geochemical studies suggest that the felsic volcanic rock in Hutti mine area is a rhyolite and at Uti and Hira-Buddhini it is of dacite composition. Scheelite occurs as veins, veinlets, stringers and blebs along fracture planes of felsic volcanics in the Hutti mine area, whereas at Uti and Hira-Buddini it is insignificant. On the basis of spatial association of metabasalt and felsic volcanics and on geochemical grounds, we interpret that the felsic volcanics might have originated by the partial melting of basalt. REE patterns of the granite, granodiorite and metabasalt of Hutti are similar to each other indicating that they could be co-magmatic. However, REE in the Hutti felsic rocks is significantly higher than in Uti and particularly Hira-Buddini mine areas. The two felsic volcanic samples drawn away from the mineralized zone from all the three mine areas were analyzed for tungsten. In Hutti one sample assayed 0.15% and another 0.062%. At Uti, in one sample it assayed 0.056% and another less than 1 ppm, whereas at Hira-Buddini, it is less than 1 ppm in both the samples. The spatially associated basalt analyzed 23 to 235 ppm tungsten, whereas granites and granodiorites have very low (<1 ppm) tungsten. Therefore, the source of tungsten in the felsic volcanics of Hutti area could be traced to metabasalt. The absence of significant amount of tungsten in the felsic volcanic of Hira-Buddini could be attributed to the lack of REE enrichment compared to REE in Hutti and Uti felsic volcanics.

Jan 1, 2007

By Clay Haynes

While the Kansas River Tunnel is a relatively short, small diameter tunnel, the shaft excavation methods implemented were long and large on innovation and use of reverse circulation drilling equipment. ATS Drilling, L.P. used mechanical excavation techniques for both soil and rock segments of the 42.7 m (140 feet) and 38.1 m (125 feet) deep shafts that were 2.9 m (9.5 feet) and 4.1m (13.5 feet) diameter, respectively.

Analysing a flotation plant?s operating performance requires accurate metallurgical sampling. Typically, the aims of performing flotation plant surveys are to establish a consistent and accurate understanding of the operation of the circuit as well as to identify potential areas for improvement. Once the data have been collected, a mass balance is required to provide a consistent set of data from which plant performance can be assessed. Mass balancing is a key skill that many metallurgists and mining industry professionals are familiar with. Mass balancing reconciles the feed and product streams throughout the plant and is sometimes used for accounting of the material entering and leaving a system (eg. JKMetAccount). However more common reasons for mass balancing are: better understanding of the flowrates within a system, assessing the quality of data obtained from sampling and surveys, and providing a key dataset for assessing and improving the performance of unit operations. Mass balancing requires practice and experience to determine if the results are reasonable. There are various software programs available to assist in the mass balancing and understanding of processing plants. This paper is focused on JKMultiBal initially developed by Gay (1993), and then later commercialized by JKTech. JKMultiBal in its current release is for balancing data in both one and two dimensions, i.e. balancing data on either sized or assay bases as well as size-by-assay. With the recent trend in flotation circuits becoming more complex, JKMultiBal has been used to gain a better understanding of the processes occurring within the circuit. This paper provides a description of the program as well as several case studies where the two-dimensional mass balancing has resulted in improvements in plant performance.

Jan 1, 2009

By D. Washington

The US economy and the demand for nonfuel minerals grew at lower rates in 1995 than in 1994. Demand for major metals, such as aluminum, copper and steel, was mixed but relatively stable. The building industry, including highway construction, helped to support modest overall growth in demand for industrial minerals. The value of processed materials of nonfuel mineral origin produced in the United States during 1995 was estimated to be $395 billion, an increase of almost 10%compared with 1994 (Fig. 1). The estimated value of US raw nonfuel minerals production during 1995 was $38billion, about 7% more than in 1994. The value of US minerals production has increased in 30 of the last 35years.

Jan 1, 1996

By K. Norrena

Grade control in open pit mining requires the specification of dig limits that account for mineral grades, economic costs, and selectivity of mining equipment. Visual identification of ore rock types is ideal, but this is not always possible in lower grade disseminated deposits where ore/waste contacts are not visually discernible. In this case, conventional grade control practice consists of a two-step procedure (1) create a map of mineral grades at some selective mining unit scale, and (2) determine practical ore-waste boundaries or dig limits on the basis of the gridded block grades or assay information. This procedure is laborious, depends on a subjective assessment of where the boundary should be, and may be economically sub-optimal. We pose the determination of dig limits as an optimization problem and solve that problem with the technique of simulated annealing. Simulated annealing has the unique advantage of being able to combine multiple non-linear constraints into a single objective function. We use maximum profitability and the ability of the equipment to mine the proposed dig limits as constraints in the determination of optimal dig limits. We require a map of expected profit for eah block. Geostatistical techniques are recommended, for mapping expected profit but not necessary. Geostatistics will provide a quantification of the uncertainty in the grades within rock types using all available blasthole samples and exploration drilling. Some variant of L-optimal estimation or kriging can be used to determine the block-by-block classification that is economically optimum. We also need the expected profit for each block. It is unrealistic to assume free selection, that is, each block cannot be extracted independently of its neighbors. The optimal balance of &apos;&apos;accepting dilution&apos;&apos; and &apos;&apos;wasting ore&apos;&apos; is achieved to maximize profit subject to equipment constraints.

Jan 1, 2001

By T. Arthur Palm, Stephen L. Bessinger

San Juan Coal Co. (SJCC) operates an underground coal mine near Farmington, NM. Continuous miners and a longwall produce 6.3 to 7.2 Mt/a (7 million to 8 million stpy). SJCC is owned and operated by BHP Billiton. The coal seam at SJCC has been shown to have a propensity for spontaneous combustion. As such, during the feasibility study for this project, it was elected to use a bleederless ventilation system on the longwall. Due to the combination of spontaneous combustion, methane liberation and, to a lesser extent, hydrogen sulfide, a typical wraparound ventilation system would not be appropriate. Three-entry gate roads are developed, and the longwall gob is sealed as mining progresses. SJCC uses a nitrogen injection system to continuously inertize the gob.

Jan 1, 2007

By Sam Ash

The Murray Mine was one of the first mechanized cut-and-fill underground gold operations in northern Nevada. At the end of 2002, mine production began to decline. So the mine entered a phase of remnant mining and began preparations to close down. The remaining mining took place along the ore waste boundary in previously condemned areas and in challenging ground conditions. To remain economically viable, new techniques were implemented in operations, geology, engineering and rock mechanics. These improvements pushed the edge of known and accepted mining practices and have allowed the Murray Mine to remain in operation.

Jan 1, 2006

By Felicity Lloyd, Stuart Kearns, Roger McLimans

The metamorphic terrane of southwestern India is a geological environment containing ilmenite source-rocks, transport drainage systems, and resultant beach sand deposits that contain altered ilmenites greater than 60wt% TiO2. As such, this environment provides a geological laboratory, from source to deposit, for the investigation of ilmenite origin, alteration, and geochemical character. Ilmenite samples from potential source rocks, river sands, and beach sands all show degrees of alteration and a variety of alteration textures (iron leaching) producing leucoxene (here defined as >70 <90wt% TiO2) and progressing to rutile (here defined as >90wt% TiO2). Distinct alteration textures are specific to different source rocks and are used together with trace element geochemistry as provenance criteria. Ilmenites are classified on the basis of their trace element content. In India, the ilmenites are classified principally according to the Mg, Nb, and Mn content and this signature defines potential source rocks, even where the ilmenite is altered to a TiO2 content of 70wt%. The trace element data may fingerprint source rocks whose ilmenite is more prone to iron leaching and that criterion has application in exploration for higher-grade ilmenites.

Jan 1, 2005

By I. T. Oramah

Despite the abundance of solid mineral deposits, Nigeria only earns about 0.5-1% of its current Gross Domestic Product (GDP) from the solid minerals sector. This is as a result of the dominance of the oil and gas industry, which has negatively affected the competitiveness of other sectors of Nigeria’s economy. The dominance of this industry has resulted in unemployment, poverty, hunger, domestic price inflation, corruption, unstable government, and higher exchange rates. These impacts are typical for economies suffering from the effects of "Dutch Disease" and the "Resource Curse". Community-based small-scale mining offers hope as an economic activity that can create wealth, employment, reduce hunger and poverty, and provide basic amenities for rural communities with solid minerals endowment. This study presents preliminary results of ongoing research into the prospects of using community-based small-scale mining in a developing country like Nigeria to move towards rural sustainable development.

Jan 1, 2011

By Charles Ronkos, Jeffrey Edwards, Brian Brodsky

The Marlin gold-silver deposit is in western Guatemala, 15 kilometers south of a major transform fault that separates the North American and Caribbean plates. A district-scale, northwest-trending graben controlled deposition of a greater than 1200 meter thick upper Tertiary quartz latite to rhyolite volcaniclastic sequence. These volcanics were subsequently intruded and unconformably overlain by a small intermediate, latite to andesite, volcanic complex. Classic low-sulfidation, quartz-calcite-adularia veins and stockwork formed a 2.2 million ounce gold deposit, in association with late-stage andesite dike swarms, along a west-northwest striking normal fault on the eastern flank of the volcanic complex.

Jan 1, 2005

The Pogo Mine, near Delta Junction, Alaska is a 2500 TPD gold operation employing processes including grinding, gravity, rougher flotation, leach, CIP, and E/W. An OCS(Optimizing Control System) expert control system has been implemented on rougher flotation in early 2008. The OCS system communicates with the Plant DCS(Distributed Control System) through OPC(OLE for Process Control) communication. The initial strategy was to control the flotation cell froth level set points to achieve target froth velocities. This strategy was enhanced by controlling both level and air flow setpoints. The flotation cell air and level are adjusted to reach cell pulling rates (froth velocities). The pulling rate setpoints for each cell are determined based on downstream capacity (concentrate surge tank level). The effect of pH and upstream disturbances is also taken into account in adjusting the air and level setpoints. Feed forward compensation is employed down the flotation row to minimize disturbances.

Jan 1, 2009

By Libby R. Ricafort, Victorio V. Pato, R. S. Pizarro

Introduction Atlas Consolidated Mining and Development Corp. (ACMDC) started gold production at its Masbate gold mine early in 1980. This involved an open-pit mine and a 3.5-k/d (3850-stpd) carbon-in-pulp processing facility (Pizzaro and Antonio, 1981). When this operation started, the mine began stockpiling sub-grade milling material averaging 1 g/t (0.029 oz per st) gold. Furthermore, geologists estimated that there were additional low grade reserves within the ultimate pit limits. These amounted to 2.4 Mt (2.6 million st) with an average grade of 1.1 g/t (0.03 oz per st) gold. The success of low cost heap leaching prompted an investigation to determine if this tech¬nique would be applicable for the low grade Masbate ore. The findings were favorable and a series of laboratory tests were undertaken. These tests indicated the amenability of this subgrade milling ore to heap leaching. Depending on ore size, gold extractions of more than 60% were obtained. To further define operating parameters for a commercial heap leaching plant, a 400-t (440-st) batch pilot plant was built and operated. These test results were used to design the first commercial heap leaching plant in the Philippines. One design concern was the control of solutions during the rainy season. Due to the material&apos;s low grade, every effort was made to minimize capital and operating costs. To this end, surplus mining equipment from the copper operations of ACMDC and used machinery in the crushing circuit were considered. Location: The Masbate gold heap leaching operations are located on the northeastern part of Masbate Island, Philippines. This is about 480 km (300 miles) south-east of Manila. Climate: The climate is moderate with two distinct periods. The dry season runs from January through June, and the rainy season extends from July through December. During the wet season, the rainfall at the mine site averages 300 mm/m (11.8 in. per month) for a total of about 2000 mm/year (78 in. per year). However, heavy downpours in excess of 100 mm/h (4 in. per hour) can occur. Geology: Four distinct rock types have been identified in the pit area. They are tuffaceous agglomerates, andesitic agglomerates, metasedimentary rocks, and hornblende augite andesitic porphyry. The tuffaceous agglomerate occupies the northern and western flanks of the mine. Andesitic agglomerates are localized distinctly in the central portion of the volcanic plug within the mine site. The eastern boundary of the mine is occupied by metasedimentary rocks, whereas, the hornblende augite andesitic porphyry occurs as an intrusive within the andesitic agglomerate and tuffaceous agglomerate. Some areas of the pit contain high proportions of clay minerals, requiring an agglomeration step in the flowsheet. This ensures satisfactory percolation through the heaps. Ore characteristics: Gold and silver are microscopically dis-

Jan 9, 1987

In September, a fleet of 363-t (400-st) Liebherr trucks became operational in Brazil and have already begun moving iron ore in Para state. Prior to the arrival of the the trucks the Brazilian fleet relied on trucks up to 218 t (240 st). With the addition of the 363 t (400 st) trucks, the fleet has since experienced the high productivity offered by Liebherr T 282 B trucks.

Jan 1, 2010