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By H. Do

In flotation, hydrophobic particles are selectively collected by air bubbles, and the bubble-particle aggregates enter the froth phase. However, less hydrophobic particles drop off from the froth phase, while more hydrophobic particles are recovered. Thus, the froth phase provides an important cleaning mechanism. In the present communication, the froth-phase recovery process has been modeled by considering particle retention times and the carrying capacities of bubbles. The model predictions are compared with the experimental data reported by Seaman et al. (2006). The results show that the froth-phase recovery varies with particle size, particle hydrophobicity, and bubble coarsening.

Jan 1, 2008

By W. W. Edgerton

Construction projects may be delivered under one contract package or multiple packages divided by discipline, geographic location, or other characteristics. Dividing the construction into contract bid packages is called contract packaging, and is a vital and strategic aspect of effectively delivering tunneling projects. The process of contract packaging considers many factors, including the type of project, location, and owner?s priorities. This paper describes the key facets of the contract packaging process used recently on several tunnel projects, reports, where possible, on the success of the process, and concludes with recommendations for applying this process to achieve the right contract package.

Jan 1, 2008

By D. J. Pandelis, W. J. Schlittler

Auxiliary Equipment pumping systems to support primary, secondary and regrind grinding circuits will be the primary focus of this paper. Every grinding system is unique and requires special design considerations for proper application of pumps to transport mill discharge. To satisfy the majority of applications, a new series of pumps has been developed by Svedala, known as World Class Pumps. Selection of these newly developed pumps for each type of grinding circuit will be presented. Specific components of selection are materials of construction, piping system, classification method, material characteristics and slurry characteristics. Both horizontal and vertical pump applications will be reviewed with emphasis on rules of pump piping and sump design.

Jan 1, 1999

By W. G. Pariseau

"The Crandall Canyon Mine (CCM) is located in the Wasatch coal field in central Utah. Extensive longwall mining at CCM preceded a decision to recover coal left in barrier pillars on each side of a set of main entries extending far into the mine. During mining in March 2007, a major bump occurred that led to cessation of mining in the barrier pillar on the north side of the mains and to the start of mining in the south barrier pillar. Subsequent loss of ground control in August 2007, through coal pillar bursts had tragic consequences with loss of six miners and shortly afterward three rescue team members. A U.S. Mine Safety and Health Administration (MSHA)report describes the events in detail (MSHA, 2008).An important lesson to be learned from CCM is the need to select a computer program suitable for pillar design. Computer programs are engineering tools and selecting the right tool for the job is essential. In this regard, minimum program requirements include capability for computing stress distribution within a pillar and adjacent roof and floor strata. The reason is simple: strength of rock is stress dependent; both vary from point to point in pillars and adjacent strata. Preferably, one should follow the evolution of stress as the mining plan is executed from start to finish to assure safety or to warn of a potentially hazardous situation developing as mining progresses.The approach to the problem posed by barrier pillar mining at CCM is conventional in the sense of applying well known finite element modeling techniques to analysis of a proposed mining plan. The engineering purpose is to evaluate the mining plan with respect to ground control questions including roof, floor and pillar safety. Results of previous two-dimensional finite element analysis indicated pillar safety was by no means assured (MSHA, 2008; Pariseau, 2008; Pariseau, 2011). Geometry of barrier pillar mining is limited in two dimensions for example, crosscuts are not seen in vertical cross sections. While three-dimensional analyses are preferred, even moderately sized regions often lead to very large problem sizes that exceed computer capabilities. However, a recent development in finite element modeling of tabular deposits allows for whole mine analysis in three dimensions. This technique involves a dual node - dual mesh concept. Both have been used separately in much earlier work, but are only now used in combination. It is possible to have an estimation of subsidence at a kilometer scale and details of stress, strain and displacement about barrier pillars, main entries and pillars, and so on at a meter scale (Pariseau, 2014). No compromise involving empirical formulas or similar guess work is required. Indeed, all calculations are based on first principles: physical laws, kinematics, and material laws. Effects of joints and in situ variability or uncertainty in strata properties, elastic moduli and strengths, may be included for greater realism. An important objective of the present study is to assess the role of three-dimensional pillar geometry in arriving at conclusions regarding barrier pillar mining versus two-dimensional results."

Jan 1, 2014

By Lim Thi Duong, Du Duy Bui, Thuat Ngoc Pham, Chuc Ngoc Pham, Que Anh Nguyen, Hoa Anh Bui, Chi Thi Ha Nguyen, Hoan Thanh Nguyen, Bac Quang Nguyen, Kien Trung Nguyen, Dung Trung Doan, Nhiem Ngoc Dao

The microstructures and kinetics of a rich iron ore ( TFe = 65.84%) of Na Rua mine, Vietnam, used for the iron production were investigated in this study. Thermal behaviors of iron ores were well-examined by heating microscopy, thermogravimetric analysis, and differential thermal analysis. After being pelletized and then oxidatively fired at 500–1200 °C for 2 h, the pellets fired at 1200 °C (P1200) displayed a hard and dense structure with a decent compressive strength of 317.9 kg/pellet whereas those fired at 500 °C (P500) had a soft and spongy structure. The reduction of iron pellets conducted in a flow of a 60–100% CO2/ Ar gas mixture at 900–1100 °C showed significantly higher efficiency than the reduction using coal. The spongy pellets showed superior performance for the reduction in the CO/Ar gas mixture compared to the dense ones, compatible with the production of sponge iron. When mixed with an amount of coal, P1200 designed for iron production in the blast furnace demonstrated an impressive reduction activity compared to P500 and previous studies. The kinetics of pellet reduction was determined by the diffusion of substances through the solid product layers having the mathematical model of 1 − 2 3 f − (1 − f )2∕3 = kt . The microstructures of pellets during the oxidative firing and reduction were also examined by X-ray diffractometry; scanning electronic microscopy; energy-dispersive X-ray spectroscopy; and Brunauer, Emmet, and Teller method.

Jun 7, 2022

By K Louie

When BHP Copper's Lower Kalamazoo Project commenced production in January 1997, two of the four original hoists had been converted to hoist ore from the Lower K level. Conversions on these hoists not only allowed hoisting from a much deeper level, but also created a higher hoisting efficiency and higher capacity as well. Conversions included new drums, new cables, SCR drives and other solid state control technologies not available when the original hoists were installed. Two of the original hoists were installed in the 1950's and the other two were installed in the 1970's.

Jan 1, 1998

By Frederick J. Murrell

No other region of the world is enjoying the tremendous growth of power use that is currently being experienced in Asia. Fortunately for the coal industry — particularly in Asia — the power plants being planned or under construction are designed to use coal as fuel. This has produced a significant increase in the demand for steam coal that, in turn, has encouraged many in the industry to develop new coal mines. Indonesia is a country that has enjoyed substantial growth in coal production. This developing country has 195 million people who live on the nearly 13,000 islands. It has quickly emerged as the third-largest exporter of steam coal, following only Australia and South Africa. Almost all coal in Indonesia is mined by surface-mining methods.

Jan 1, 1996

Traditional loading systems have relied for many years on wheel and track loaders, power shovels, conveyor belts, and more recently, hydraulic front shovels. Each has certain advantages and disadvantages, depending largely on job conditions. Hydraulic backhoes were introduced several years ago as still another truck loading option. At first, buckets were small and backhoe use was limited to small earthmoving projects. Now, as backhoes are equipped with shorter sticks and bigger buckets to move larger quantities of earth. The "mass excavation" concept offers an excellent truck loading option in many situations. System Development and Advantages Mass excavation was first used successfully by contractors in site development and highway construction, loading both on-highway and off-highway trucks. Operators were able to take advantage of the excavator's ability to work in poor underfoot conditions and dig in tough materials. The technique was first applied to mining in the kaolin mines of central Georgia. Kaolin, one of the world's most abundant minerals, is used to make paper, paint, ceramics, rubber, plastics, and many other products. Since kaolin clay is slippery when wet, load-out with wheel loaders is very inefficient. Also, kaolin is found in very spotty deposits due to the weathering process involved in its formation. Consequently, draglines are also impractical for kaolin mining since they don't have the mobility to move between clay deposits. In response to these mining conditions and kaolin characteristics, mines began using excavators in mass excavation as early as 1976. They have developed a system that takes advantage of the excavator's •high penetration and breakout force in tight materials; •fast-cycling hydraulics; •ability to work in poor underfoot conditions; and •mobility in comparison to draglines. This loading method has been successful in Georgia's kaolin mines and now can be applied to other mining operations as well. The excavator's ability to carefully dig spotty ore deposits is an asset at uranium mining operations. Any mine can take ad-

Jan 3, 1982

By Steven W. Hunt, Isabelle Lamb, Steven B. Fradkin

Groundwater control is generally an important consideration and significant source of risk during most tunneling projects. Proper baselining of groundwater conditions requires: 1) a thorough understanding of the geological environment; 2) a focused site investigation; 3) identification of construction and adjacent property damage risks associated with inflows and short and long term piezometric level changes; and 4) consideration of contractual issues including restrictions on means and methods and pay items for associated work. This paper provides an overview of groundwater baselining issues and risks based on selected design studies and construction case histories.

Jan 1, 2005

By H. Lyn Bourne

This marks the 15th consecutive year for this column. During 1995, readers were asked to supply royalty data for construction raw materials especially for states where none is available. The response was discouraging and royalty data are still missing for several states for either sand and gravel or crushed stone. Several readers have said that this article has merit but more new information is needed to justify its continuation. Several articles and pieces of news relative to mineral royalties appeared in the trade journals. R. Lee Aston (E&MJ, November, 1995, p. 16N) described South Australian royalties as amended by the government in1994. The royalty rate (a percentage) was lowered but the assessed value for minerals was raised and the current rate amounts to 20 cents//t (18 cents/st).

Jan 1, 1996

By Stephanie Singarayer, Damodara Reddy Chinnasane, Mike Yao, Danielle Pelletier

Mining at Vale’s Creighton Mine has been active for nearly 120 years in Sudbury, Ontario, Canada. Being the deepest mine in the Sudbury region, mining induced seismicity is a common occurrence at Creighton Mine. Over the past five years, 26 large magnitude seismic events ranging from 2.5 Mn to 3.7 Mn (Nuttli) have occurred. Out of these large magnitude events, three 3.0+ Mn events occurred between April 2020 and January 2021. The majority of the 3.0+ Mn events are believed to be the fault-slip type that could be linked to the known major geological structures and/or long-term effect of mining over many years. The recent large magnitude events are believed to be triggered by high induced stresses while mining the first few stopes of a new lower horizon in the top-down centre out mining sequence.

Apr 26, 2022

In this work, the crystallization of Carnallite from waste brine of Qaidam Basin in Qinghai province was studied based on NaCl-KCl-MgCl2-H2O phase diagram. According to this study, a new crystallization pathway to recycling waste brine was developed. The carnallite salt was formed by using this technology during the waste brine evaporation. The experiment data shows that 5 tons of waste brine was required to form one ton of the carnallite. The average grade of carnallite prepared by using this procedure was about 19.40% of KCl, 16.92% of NaCl, 28.80% of MgCl2, and 0.82% of CaSO4. This study provides an opportunity to utilization of the waste brine.

Jan 1, 2012

By John W. Shield

Oxide gold reserves are being rapidly depleted, especially in regions with long histories of gold mining, such as the Black Hills of South Dakota. However, these districts often have substantial additional deposits, where gold is refractory. It is not amenable to traditional cyanide extraction due to the presence of sulfide minerals that encapsulate or otherwise preclude the economic extraction of the gold. Several technologies have been developed to render refractory sulfide deposits amenable to traditional cyanide processing. These include roasting and pressure autoclaving. Unfortunately, these oxidation processes require substantial capital investment and incur significant operating costs. Microorganisms that obtain energy for their life processes by the oxidation of iron sulfides can be used to treat gold-bearing refractory sulfide minerals. As the bacteria convert the sulfide to sulfate, they expose any gold associated with the sulfide matrix. This makes the gold amenable to cyanide extraction.

Jan 1, 1996

By R. B. Tippin

Great Salt Lake Minerals & Chemicals Corporation (GSL), a subsidiary of Gulf Resources & Chemical Corporation, is located on the east side of the Great Salt Lake, approximately 20 miles from Ogden, Utah. GSL processes brine from the north arm of the lake to produce potash, salt cake, salt and magnesium chloride brine. Potash fertilizer, in the form of K2SO4 is GSL's primary product. The GSL Sulfate of Potash Complex The GSL potash complex (depicted in Figure I) is divided into a solar evaporation pond system and the process plants. The solar,evaporation system consists of a 17,000-acre (68.8 Km2) ponding operation where the various salts deposit during the summer evaporation season, and a harvesting operation which recovers the deposits during the remainder of the year. The harvest is either preconcentrated in the flotation plant or processed directly in the chemical plant where sulfate of potash (SOP) is produced. The chemistry of the lake brine results in a solar deposit con¬taining primarily kainite (KCl-MgSO4.3H20), schoenite (K2SO4?MgSO4^ 6H2O), and halite (NaCI), with some carnallite (KCl.MgCl2.6H20) and epsomite (MgSO4.7H20). Other minor minerals may be deposited, depending upon the weather during the evaporation season. Each year, the solar deposit in the evaporation ponds will greatly depend upon the summer weather conditions, which have in the past proven to be quite unpredictable. Weather may alter both the quantity of the solar deposit and the composition of this deposit. During, a "short" evaporation season, the tonnage deposited decreases, but depending upon the short-term weather, the potash mineral content

Jan 1, 1977

By L. Shevenell, L. Stillings

The Acid Drainage Technology Initiative-Metal Mining Sector (ADTI-MMS) has established a Pit Lake Committee to enhance the science and understanding for the long-term management of pit lakes. Participation in this new committee is from members of federal and state agencies, industry, and academia, including numerous individuals representing 10 states. Work has begun on a pit lake literature search and review, database, classification, and sampling and monitoring procedures document. Coordination with the International Network for Acid Prevention (INAP) has been established. Future work will include preparing a prediction and assumption verification document, a report identifying variables upon which water quality is dependent, and an applied remediation technologies document, including an evaluation of the effects of backfilling.

Jan 1, 2002

By VIVEK KUMAR HIMANSHU, Murari Prasad Roy, Kaushik Dey, Rakesh Kumar Singh, Ashish Kumar Vishwakarma

Sublevel stoping is the most popular and practiced mining method in underground hard rock mines. Proper planning and its execution is the key requirement for stope extraction using this method. The stope extraction has been a challenging task since decades. The major reason is the unavailability of free faces as compared to opencast bench blasting. The geological and geotechnical parameters change gradually even within the stope itself. So, the blast design parameters should be planned according to the scenario of the upcoming ring. The blast design parameters like burden, toe spacing, inclination of blastholes, diameter of blastholes, charge density of explosive, etc., play an immense role in the rock damage. For the proper breakage of rock, the movement of burden is the prime objective. To study this, an explicit dynamic based modeler of M/s Ansys was used. The burden values were varied from 20 to 65 times of blasthole diameter to assess the optimum burden value during the study. The models were simulated for the rock having uniaxial compressive strength as 35 MPa and 102 mm blasthole diameter. Three holes were simulated having depth around 14–14.5 m. Different blast design parameters and respective blast-induced ground vibration have also been measured at the experimental site. The core samples of the rock present at the experimental site have been used for the evaluation of geotechnical parameters. These geotechnical parameters were used in the simulation models. The volume of rock excavated along the free face has been calculated in each model by varying the burden. It has been found that the burden value can varies from 35 to 40 times blasthole diameter (3.6–4.1 m) to achieve a greater volume of rock along the free face for 102 mm blasthole diameter and rock of 35 MPa uniaxial compressive strength.

Dec 22, 2023

By J. R. Shultz, R. J. Lambert

One of the present trends in the mining industry is the increased use of mining contractors. In the past, many project owners have utilized mining contractors for topsoil stripping or overburden removal, usually on a short-term or periodic basis. In recent years, mining contractors have not only removed the overburden, but mined the product as well. Why is this change occurring? A prevalent trend in the mining industry appears to be the outsourcing of non-core and non-strategic functions, allowing producers to focus more on areas of technical expertise where higher incremental value is added—that is the processing, refining, and marketing of the product. As capital allocation becomes more critical, this trend is likely to continue.

Jan 1, 2002

By N. S. Kim

Silver paste including nano sized particles maintains conductivity in high temperatures without forming oxide layers. In the industry, printing process produces wasted silver paste inside the cylinder and on silk-screen. Pyrometallugical silver recycling methods have environmental problems and do not extract pure silver after removing polymer and organic materials during the extraction process. In this study a simple wet process, of recycling the waste silver paste, using ammonia, was conducted. Silver ion extraction yield was increased using oxidant in the ammonia solution. Possible extraction yields, such as pH, concentration, temperature of ammonia, oxidant concentration and the extraction time. The particles that were obtained after the extraction process will be used as porous hydrophobic catalytic and applied to AI mask and hydrophobic ink. Keywords: Waste silver paste; Ammonia; Hydrophobic porous support

Jan 1, 2009

By James E. Lawver

Part I describes the general geology of the Florida deposits. As the lucrative Bone Valley Formation is depleted, replacement production will move progressively into areas of total Hawthorn production. The reserves of the immediate future are a mixture of two distinct ore types referred to as the upper (high grade) zone and the lower (low grade) zone. The upper zone is somewhat similar to the Bone Valley Formation that has been Florida's source of production for the past 100 years and will respond favorably to present beneficiation practices. By contrast, the lower zone ore contains significant quantities of dolomite that must be removed in order to produce an acceptable grade pebble or flotation sized product. Part II reviews past practice and describes future trends in mining and ore transportation. This presentation (Part III) is confined to the problems of beneficiation, waste disposal, and environmental regulation.

Jan 1, 1983

THE QUARTETTE Mine near Searchlight, NV, a mine that first operated in the 1890s, could begin processing ore again by September. Jetco Enterprises Inc. plans to work through the tailings and ore close to the surface followed by plans for an openpit mine. It is one of at least three new mining efforts in the region, the Associated Press reported. Another is north of Searchlight, with yet another across the Colorado River in Arizona, east of Bullhead City. Gold mining is rare in southern Nevada. The area generally lacks the rock type that contains gold deposits. Restrictions on federal wilderness areas and protections for the desert tortoise also play a role. Gold veins in the region are generally small and erratic in length and height, Bill Durbin, a geologist and chief of southern Nevada operations for the Nevada Division of Minerals told the Associated Press. L.R. Tad Tinnell, president of Jetco Enterprises, has long eyed the mine. From 1993 to 1995, he explored and drilled on the property, which was still owned by Searchlight Mercantile.

Sep 1, 2013