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By Steven K. Duke, Jay Arabshahi

An economic, real-time probe drill monitoring system was developed for Metropolitan Water District’s Arrowhead Tunnels project to quantitatively evaluate ground conditions ahead of a TBM. This system digitally records hydraulic feed, rotation, and percussion pressures and calculates drill advance rates during drilling. These data are computer synthesized to develop a digital representation of the ground ahead, and the resulting “picture” of the ground is distributed to the project team to assist with tunnel construction decisions (i.e., targeting grout holes, optimizing mine-cycle lengths, and avoiding becoming stuck). The analysis and interpretation procedure has now been calibrated and refined using over 5,000 m (3 miles) of geologic face mapping data.

Jan 1, 2007

By N. L. Parduhn

Populations of Bacillus cereus spores are elevated in soils over four subsurface gold deposits in the western United States. Large deposit-to-background ratios of B. cereus populations were obtained in soil traverses over the Minnesota vein deposit, Empire District, Colorado (maximum 50:1); the Shasta (maximum 3,500:1), and Evening Star maximum 18,000:1) vein deposits, Shasta County, California; and the Hog Ranch disseminated gold deposit (maximum 40,000:1) in Washoe County, Nevada. Small increases in the concentration of toxic metals in the soil may be responsible for the elevated spore populations. The observed elevation of B. cereus spore populations near these gold deposits indicates that the method should be further investigated as a potential exploration tool.

Jan 1, 2013

A Mineração da Trindade (Samitri) is a major Brazilian iron ore producer. Founded in 1939, privately owned Samitri operates six mines with a total production capacity of 14.5 Mt/a (16 million stpy). The mines are located in southeastern Brazil in the state of Minas Gerais. They are operating in the iron ore quadrangle, Brazil's primary iron ore-producing region. In addition to iron ore production, Samitri has the capability to produce 350 kt/a (386,000 stpy) of ferruginous manganese ore from two mines, also located in the iron ore quadrangle. Historically, about 70% of Samitri's production of lump ore, sinter feed and pellet feed is exported. Destinations include Belgium, Luxembourg, France, Germany, Trinidad and Tobago, China, Turkey and the United States. Alegria Mine In September 1989, Samitri started a new processing plant to treat itabirite, a low-grade iron ore. The goal of the plant was to produce sinter feed (coarse fraction) and pellet feed (fine fraction). Primary separation of sinter feed from pellet feed was accomplished with conventional vibrating screens making a 0.4-mm (40-mesh) cut. The screen oversize was stockpiled as sinter feed. The undersize was deslimed with hydrocyclones and upgraded by conventional froth flotation. Resulting pellet feed grades ranged from 3% to 3.5% Si02. A change in pellet feed requirements by Samarco Mineração SA, a Samitri subsidiary, called for Si02 levels below 1 % and increased production levels. Moreover, market demands called for a change in sinter feed size distributions. Unfortunately, lower pellet feed Si02 levels could not be achieved with the existing process. This was because of the presence of 35% +0.15 mm (+100 mesh) in flotation feed. Flowsheet development. Laboratory and pilot-plant studies conducted at Samitri's research facility found that to achieve lower Si02 levels, the +0.15 mm (+100 mesh) in flotation feed must be kept below 5% to 10%.

Jan 1, 1997

By Thomas E. Garnar

Zirconium and hafnium are the twin elements of the periodic table because they are always found together. They resemble each other so closely that hafnium was not discovered until 135 years after the discovery of zirconium. Zirconium was discovered by Klaproth in 1789 and isolated 35 years later by Berzelius. Because hafnium's chemical properties are so close to those of zirconium, it was not discovered until 1923 when Coster and von Hevesy detected it using X-ray spectrographic analysis. These elements occur most commonly in nature as the mineral zircon (ZrSiO,) and less commonly as baddeleyite (ZrO,). They also are found as a variety of other silicates. Zircon was identified as a component in alluvial and beach sands in 1895, but it was not produced in any quantity until 20 years later. During World War I, it was produced as a coproduct of beach sand mining for titanium minerals just south of Jacksonville Beach, FL, and was patented as a refractory. It was not until the 1930s, when Zircon Rutile, Ltd., began mining at Byron Bay on the east coast of Australia, that zircon was first used as foundry sand. Later in the 1940s, NL Industries and Humphreys Gold Corp. began production of zircon sands from fossil beaches in northeast Florida. Baddeleyite first became available as a commercial product in 1916, but never in the quantity of zircon. Zircon holds a unique position as an industrial mineral because it is used for both its physical and chemical properties and as an ore of zirconium and hafnium metals. Australia is the major zircon producer followed by the Republic of South Africa and the United States. Zircon is also produced in India, Sierra Leone, Sri Lanka, Malaysia, the former USSR, China, Thailand, and Brazil. The location of world zircon mines, baddeleyite mines, and undeveloped zircon ores are shown in [Fig. 1]. World production of zirconium mineral concentrates is shown in [Table 1].

Jan 1, 1994

By P. J. Cook

Comminution is one of the fundamentals of mineral processing, requiring large expenditures to be made on capital equipment, installation, power and maintenance. The trend toward lower grades and higher operating costs, mean mining operations are becoming increasingly marginal. The challenge is to improve and more importantly, utilize crushing and milling technologies that provide for reduced capital and operating costs whilst providing increased unit efficiencies. The Svedala Barmac Autogenous Crushing Mill presents such an opportunity by providing many of the cost savings and production increases required by its ability to produce a finer mill feed size and realize reduced energy consumption. This paper briefly describes the operation of the Svedala Barmac Autogenous Crushing Mill and reviews its benefits towards improving the efficiency of crushing and milling operations.

Jan 1, 1999

By A. G. Yapo, T. W. Camm

"Mining plays a key role in the development of modern civilization as a source of essential raw materials and provider of essential fuels, producer of jobs and a factor in support of the international balance of monetary payment (Camm, 2014). Professionals in mining locate, develop, design and manage ore deposits in an environmentally safe and profitable manner. As mineral deposits become increasingly scarce, new challenges face the industry. A current trend is to an increased emphasis on underground mining techniques for deeper deposits. Operations are safer now than before as companies understand better their work environment and the importance of mining responsibly.A continual challenge for the industry is accurately reflecting the costs and selling price of ore. An enduring characteristic of mining is the situation where the market typically determines the price of a commodity; the main control a company has on the bottom line is to control the cost of production.An attempt to bring light and clarity to the cost of their business will give a better idea to investors on the true profitability of the mining business. Gold producers face this struggle to accurately reflect the cost of production while also seeking to attract the interest of the investment community (Hill, 2013). In order to have a consistent format to report on their production costs, leading gold producers, through their alliance inside the World Gold Council (WGC), worked on the adoption of a new cost framework: the all-in sustaining cost (AISC) and all-in cost (AIC).Since 1996, the traditional cash cost reporting has focused only on the mining and processing costs incurred in mining an ounce of gold, which included the costs of goods sold (labor, energy, and consumables costs) and royalties (Table 1). But cash cost reporting ignores many important aspects, like sustaining capital, general and administrative expenses and site rehabilitation at the end of the mine life (Whelan, 2013). The cash cost was used to attract many investors into the business. In fact, the high gross margin (sales minus cash costs) has been promoted in past decades by the industry instead of the net or operating margin. As a result, even when the gold price was high, nearly $61/g ($1,900/oz) in August 2011, gold producers were not reporting excessive profits in their cash flow/income statements, to the disappointment and incomprehension of investors (Milstead, 2014). The truth was simply that the other costs omitted in the traditional cash cost were reducing the apparent profits.The disconnect led to a need for more accurate cost reporting in order to win back investor confidence and provide better understanding of gold mining economics. In 2012, the senior gold mining companies, including Gold Fields, Barrick Gold Corp. and Newmont Mining Corp., worked with the WGC to develop a new measure. This resulted in the June 2013 publication of the new framework AISC and AIC, which has been widely embraced by the sector since Jan. 1, 2014 (WGC, 2013).The adoption of the new cost template would have the dilemma of showing the real profitability of gold mine properties, which might alleviate taxes from governments and legislators, but it might also scare off investors toward more lucrative industries if not winning back their confidence."

Jan 9, 2017

By P. B. Marchant

Bioleach testing and piloting was conducted on refractory gold sulphide concentrate from Austin Gold Venture in Nevada during 1988. The objective of the test programme was to determine the technical and commercial viability of bioleaching as a concentrate pretreatment step prior to gold extraction by cyanidation as an alternative to shipping concentrate to the smelter. Baseline CIL cyanidation typically resulted in < 20% gold extraction from the Austin concentrate. Bioleaching enhanced gold extraction up to 95% using conventional CIL techniques. This paper summarizes the bioleach test programme and results, including pilot plant studies onsite, and describes aspects of the commercial design for a possible retrofit of the Austin flotation tailings leach circuit to accommodate 20 tpd and 40 tpd capacity concentrate bioleach facilities.

Jan 1, 1989

By R. Hedin, M. Dunn

The Pennsylvania Department of Environmental Protection (US EPA 319 program) provided funding to aid a public-private effort in the installation of an environmentally-friendly system to treat abandoned mine drainage at Jennings Environmental Education Center (Pennsylvania Department of Conservation and Natural Resources). Through this cooperative effort among state and federal agencies, mining, excavation, and environmental companies, college and home school students, Girl Scouts, and volunteers, a successful multi-component passive system, readily accessible for upgrades and public education/research activities, was built. 90 people were directly involved in construction of this award-winning system and about 1000 people annually benefit from the educational opportunities.

Jan 1, 2002

By A. Martin

Detailed porewater profiles of arsenic and other interstitial metabolites were used to assess the relationship between trophic status, sediment redox chemistry and arsenic mobility in a historic tailings repository. The results demonstrate that in eutrophied systems which exhibit greater sediment oxygen demand, the depth of the Fe(III) redoxcline, and hence depth of arsenic release, may lie in close proximity to the sediment-water interface. As a result, arsenic scavenging mechanisms are significantly reduced, resulting in a greater flux of arsenic to the water column. Such considerations have important implications for the management of pit lakes, tailings ponds and contaminated lakes which may consider: 1) the discharge of sewage to the water body during operations; and/or 2) post-closure fertilization as a remediation strategy.

Jan 1, 2002

By I. S. Parrish

This article offers one of the infrequent looks at Chinese mining. It includes a brief review by Parrish of a tungsten symposium held there and his comments on and impressions of the mines he visited. In early Oct. 1981, a Symposium on the Geology of Tungsten was held in the Peoples Republic of China. There were approximately 100 participants. Half of them were Chinese. The remainder included representatives of the United Nations, geologists from other nations in Southeast Asia, and 10 invited specialists from other countries. The invited guests included K.F.G. Hosking of the Camborne School of Mines, United Kingdom; C.S. Hutchinson of the University of Malaysia; K. Mattson of LKAB Int. AB, Sweden; T. Kwak of Latrobe University, Australia; K. Sato and S. Ishihara of the Geological Survey of Japan; M. Clarke of the Department of Mineral Resources, Indonesia; P. Bateman of the US Geological Survey; and the author. R. Horsnail of Amax was also invited but was unable to attend because of delayed visa clearance. The meeting was noteworthy because the Chinese were presenting more than half the papers. In addition, following the formal session, everyone was taken to the famed Jiangxi tungsten district and toured four mines there. Organization and Background The idea for a symposium on tungsten geology was brought up in late 1979 during a visit to China by the Economic and Social Commission for Asia and the Pacific (ESCAP) and, in particular, by members of the Regional Mineral Resources Development Centre (RMRDC) of the United Nations. Discussions continued and in the spring of 1981 invitations were sent to selected geologists throughout the world. China&apos;s Ministry of Geology handled arrangements, scheduling, and logistics. Travel to China and all correspondence before the symposium were coordinated by the Bandung, Indonesia Bureau of RMRDC. All costs in China were met by the Peoples Republic of China. Airfares and "per diem" enroute for participants were paid by respective governments, sponsors, or individuals. On Oct. 10, visiting participants entered China from Hong Kong. The author and a few others traveled by train to Guangzhou (Canton). Most of the group flew in the next day. The entire group was then taken to Nanchang, traveling by sleeper train and arriving on Oct. 11. The symposium group stayed at the Kiangsi Hotel, where the meetings were held. Meetings Oct. 11 was a day of orientation and rest. The group was taken to an art museum and treated to a Chinese opera movie. The formal meetings began on Monday, Oct. 12. Simultaneous translations aided presentations, though more than half the Chinese speakers delivered their talks in English. The acoustics and sound system were excellent, and the Chinese provided 35-mm and overhead projectors. There was no screen, however, and the yellow, painted wall that was used detracted from projection clarity. In general, the Chinese papers were detailed, thoughtful, and professional. Some, naturally, were stronger than others. Taking them as a unit, one derives the following sequence to the Chinese approach to tungsten exploration: (1) Geologic investigations with mapping at a scale of 1:200,000 accompanied by only minor geochemical or geophysical work. (2) Geophysical investigation with regional gravity and magnetic surveys directed toward identifying deep, tectonic systems and seeking granites in thick, crustal environments. (3) Geochemical sampling in-

Jan 6, 1982

By M. J. Farrell

Mining is a significant emitter of greenhouse gases and is the focus of increasing attention from green groups and regulators. Miners need to know their own carbon emissions and how they compare with the rest of the industry. Miners and mining companies need to know where they fit in the emissions curve. Who is in the bottom quartile? This article is based on research report data from minecost.com and Metalytics Pty Ltd which detail the specific carbon dioxide emissions for 208mines producing 90% or more of western world copper, zinc, lead and nickel in 2007. The copper and nickel mines also include Norilsk in Russia, KGHM in Poland and Kazakhmys in Kazakhstan. This is the first time that such information has become available.

Jan 1, 2009

By G. Barelli, C. Giusti, W. H. Langer

Natural aggregate – sand, gravel, and crushed stone – is the number one non-energy mineral resource in the world in terms of both volume and value. A plan for the sustainable development of aggregate resources can include: 1) policies and economic incentives to encourage identification and protection of potential resources, 2)efficient quarrying and processing of aggregate, 3) efficient use of primary aggregates, 4) greater use of recycled, waste, or substitute material, 5) inclusion of costs of all environmental impacts in price of material, 6) reclamation to beneficial secondary uses, and 7)identification of objectives, targets, actions, and sustainability indicators. Quarrying can also contribute to sustainable ecosystems through natural habitat reclamation.

Jan 1, 2003

By George H. Klein, B. Kent Merritt, Anthony Crisci

During the past decade, over 114-km (71-mi) of 0.25-m (10-in) to 3.7-m (144-in) finished diameter tunnels have been driven below Metropolitan Houston as part of a major program of water and wastewater improvements. This large effort has seen the introduction of midwestern technology with over 18-km (11-mi) of man-entry pipe jacking and European and Japanese technology with over 21-km (13-mi) of microtunneling. Owing to the high water table; a stratigraphy consisting of stiff fissured clays containing numerous layers, channels, and lenses of water-charged sands and silts; and active faults, many challenges existed for designers and contractors alike.

Jan 1, 1991

By R. N. Tempel, M. Lengke

Arsenic sulfide (orpiment, realgar, amorphous AsS and As2S3) oxidation rates were measured in mixed flow reactors at pH-2 and at temperatures of 25 ° to 30 °C. The measured oxidation rates for arsenic sulfide solids by dissolved oxygen are in the range of 10-11 to 10-10 mole m-2s-1 after being normalized to final surface area. The order of arsenic sulfide oxidation rates decreases at pH-2 from amorphous AsS > realgar > orpiment > amorphous As2S3. Compared to pyrite, arsenic sulfide oxidation rates are approximately 1.5 to 15 times slower than pyrite oxidation rates at pH-2.

Jan 1, 2003

By Colin C. Harris, Jie Zheng, P. Sornasundaran

Powder surface and polymer structural changes during stirred milling have been studied as a function of grinding time, solid concentration and polymer molecular weight. It was found that specific surface area of limestone particles can be increased over 100% by using polymer additives. Particle surface and polymer structure were also found to change during grinding. Powder surface and polymer properties have been determined using Surface Tension, Fluorescence, TOC and HPLC/GPC analysis, and surface and polymer properties are correlated with operating variables and the mechanisms involved are explored. Particularly, the fragmentation of the polymer molecules was found to occur during long term grinding and this was beneficial for ultrafine grinding.

Jan 1, 1998

By Timothy J. Napier-Munn, David M. Weedon

A model of mineral liberation was developed using back calculation techniques to determine breakage/liberation parameters in a similar manner to the way breakage parameters are determined in the Population Balance Model (PBM). Comminution and liberation data was collected from grinding mills operating at Pasminco lead/zinc mine Broken Hill, and Mt. Isa Mines copper concentrator, Mt Isa, Australia. Laboratory scale single particle breakage tests on ore samples from these sites were undertaken using a twin pendulum breakage device. Break- age/liberation parameters were then determined for several mills using back calculation techniques. The liberation/breakage parameters were then used to simulate mill liberation performance under varying conditions.

Jan 1, 1996

By Wayne Wride, Amy Lamb, Debra Sonntag

In today&apos;s "information age", we have the ability to collect volumes of data about a company&apos;s performance. The challenge is to turn that data into information employees can understand and use to fine-tune equipment, modify work processes, and ultimately manage production. Software programs have increasingly given end users control over what data is used and how it is presented. Kennecott has implemented an information system capable of collecting and storing data at the primary level. This enables plant personnel to transform historical data into information for action. Kennecott plans to expand its data collection and use trending and reporting capabilities to move toward a fully optimized operation.

Jan 1, 2000

By L. Lacerda

Shotcrete is widely accepted as an indispensable form of ground control around the world. Other Surface Support Liners such as mesh have been around as long as shotcrete while other Thin Support Liners (TSLs) have been introduced in recent decades. TSLs, however, have yet to replace shotcrete in many applications believed to be “perfect” for them. On the other hand, some recently introduced technologies may be on the brink of meeting most surface rock support requirements economically and safely. This paper will discuss rockfall statistics, small rockfall prevention and compare different surface support liners such as mesh, shotcrete and TSLs. Additionally, a shaft sinking TSL application example will be presented.

Jan 1, 2004

By Peter Keppler, Stephen D. Bundy

"Due diligence" is a review or audit of a facility or business to assess and quantify risks and operating status before an acquisition. Due diligence findings can be used to negotiate the price, general terms, and indemnification provisions in the purchase and sales agreement. In addition to assessing out- standing liabilities, necessary capital improvements, and the adequacy of operating budgets, due diligence should include "nontechnical" considerations, such as local community acceptance and relations, and the effect on the company&apos;s public image and operations. This paper will discuss how these considerations can be addressed in the due diligence process and factored into the transaction. Also, innovative means for risk reduction and risk transfer, during and after the transaction, will be discussed.

Jan 1, 2001

By M. Z. Dogan, M. S. Celik, G. Onal, O. Ozcan, I. Yildirim

A fluorite ore (51.85 % CaF2) containing high contents of calcite, quartz and iron oxides was upgraded by flotation using a new reagent, oleoyl sarcosine (OS). In addition, quebracho and sodium silicate were used as depressants for calcite and quartz, respectively. The effect of pH, collector and depressants concentrations on grade and recovery was determined with the aim of optimizing the flotation conditions. Application of the two-stage cleaning achieved a concentrate assaying 92.17 % CaF2 with 80.1 % recovery. The Si02 content (0.76 %) was below the required level of 1 % SiO2. The mechanism of interaction between OS and fluorite, as compared to oleic acid, is also elucidated based on the zeta potential measurements.

Jan 1, 1993