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By Charles F. Coleman

Kinetics studies and other rate measurements are reviewed in the amine extraction of uranium and of some other related and associated metal ions. Equilibration' is relatively fast in the uranium sulfate systems most important to uranium-hydrometallurgy. Significantly slow; equilibration-has ' been encountered' in some other systems. Most of the recorded rate information, both qualitative and quantitative; has come from exploratory and, process-development development work, while some kinetics studies have been directed specifically toward elucidation of, extraction mechanisms. In contrast to some other extraction systems, relatively little attention has been given to the kinetics of uranium extraction by amines. This is because investigators have not been troubled by slow extractions. Instead, when rate limitations have been of concern in amine extraction (Amex) process developments, they have been mainly from slow phase disengagement rather than from slow equilibration. Nevertheless, taking uranium together with several other elements that are closely related to it or associated with it in typical processes, a considerable body of rate information has been recorded.

Jan 1, 1979

By H. R. Manouchehri

"Pyrrhotite (Po) is one of the most abundant sulfide minerals in processing industry and must be rejected in most cases. Particularly, Po rejection and its selectivity against pentlandite (Pn) have long been a challenge due to similarities in the mineral composition of the two minerals and the collectorless flotation characteristics of Po. Xanthates have been widely used to promote sulfide mineral flotation; however, in the presence of xanthates, the redox potential established at the mineral/solution interface is most important, determining the flotation performance. In this paper, the importance of electrochemistry in Po and Pn flotation has been demonstrated and a comprehensive study was conducted on two different feed streams (i.e., magnetic concentrate and scavenger cleaner streams, containing magnetic and nonmagnetic forms of Po, respectively), from Vale’s Clarabelle Mill in Sudbury, Ontario, with an objective to determine if improvements in Po rejection and Pn recovery could be achieved by controlling pulp electrochemistry. By conducting a series of flotation tests under different Eh conditions and reagent usage schemes, it was revealed that higher Po content in the magnetic stream may protect Pn from being oxidized, improving Pn recovery. The results indicated that at low oxidizing pulp chemistry, the rest potential for the Pn is still high enough to allow the formation of dixanthogen to promote its flotation. Using a Pt electrode, it was found that by controlling pulp potential at -50<Eh< +50 mV, the Pn recovery and Po depression would be satisfactory. The results, using mineral electrodes (Outotec Chena analyzer), indicated that selective separation can be achieved if low-to-moderate oxidation potentials (0 to 100 mV) or reduction (0 to -100 mV) potentials are monitored using Pn and Po electrodes. Mixing two streams at 50:50 wt % would be possibly beneficial in selective separation.IntroductionPyrrhotite (Po), Fe1-xS, is one of the most abundant sulfide minerals in the processing industry. It is an iron-deficient sulfide that occurs either in monoclinic or hexagonal form. The monoclinic one is richer in sulfur and is ferromagnetic, whereas the hexagonal Po is poorer in sulfur and has no magnetic properties. In general, the ferromagnetic properties of natural Po increase with increasing sulfur content. Although Po holds significant iron content, it is not used as a feedstock for the iron and steel industry due to the difficulty in achieving complete removal of sulfur. The common availability of iron oxide ores makes the iron sulfides irrelevant for the steel industry."

Jan 1, 2015

By James Dunn

“The strongest argument of the detractor (of mining)is that the fields are devastated by mining operations ...They argue that the woods and groves are cut down, for there is need of an endless amount of wood for timbers, machines and the smelting of metals. And when the woods and groves are felled, then are exterminated the beasts and birds, very many of which furnish a pleasant and agreeable food for man. Further, when the ores are washed, the water which has been used poisons the brooks and streams, and either destroys the fish or drives them away.” Georgius Agricola, 1556, De Re Metallica, translated by Hoover, 1950. Technical problems associated with the cleanup of historic mines are not new. Nor are they unique to the mining industry or the governmental agencies addressing them. Both face the same issues and challenges of defining the problems, evaluating remediation options and finding the most economic and effective solutions.

Jan 1, 1999

By A. Nieto

This article is a review of previous discussions about underground mining method selection and classification with the purpose to clearly define and classify the two groups of variables (indicators) involved in the mining selection process: key deposit indicators (KDIs) and key mining method indicators (KMIs). This paper provides a simple and clear approach for the classification and selection of a feasible underground mining method based on a predetermined set of favorable deposit characteristics, which are defined as key deposit indictors (KDIs). This article also gives a summary of the key advantages and disadvantages associated with every underground mining method based on their key mining indicators (KMIs). The selection method given in this paper is based on defining field KDIs and comparing them to the KDIs that are favorable to every considered mining method. By cross validating a matrix of favorable KDIs, the paper presents a simple approach to rank several underground mining methods using a scale from favorable to less favorable accordingly to the ore deposit characteristics (KDIs). KMIs are used to further complement KDI rankings by analyzing every method’s KMI performance based on the expected productivity of the mining operation being considered. To further assist the reader through the selection process, this paper gives basic sketches representing each of the primary underground mining methods discussed in this paper. Each method is given using the same 3D isometric view as spatial reference to assist the reader with visual interpretation and comparison between methods.

Jan 1, 2010

By Ramiro da Conceição do Nascimento, Horst Guenter Feldhagen, Rafael Piumatti de Oliveira

Mixed hydroxide precipitate (MHP) is a nickel intermediate product that has economical benefits to downstream leaching of lateritic marginal ores. Usually, this product is subsequently processed and refined to produce nickel by hydrometallurgy, but an alternative route can be made integrating hydrometallurgy and pyrometallurgy. Assessing the overall consumption of ferroalloys to obtain stainless steel, as an increasing practice performed in China, the synergy of nickel extraction from laterites by leaching and precipitation asMHP with the production ofMHP agglomerates applied as rawmaterial to furnaces of ferronickel production is a very attractive practice. This work aims to further the technological development of an agglomerated product feasible to hydro-pyro integration. The agglomeration experiments were performed by traditional pelletizing (firing the pellets) and cold bonded pelletizing (aging the pellets by appropriate stocking). Appropriate compositionswere prepared withMHP, additives and binders for each of these routes. A specific study of binder composition was made to find an adequate melting point. The produced pellets were tested to prove their properties by crushing strength tests. The standardization applied to iron ore was followed. The best result of crushing strength was 98.52 daN/pellet. The agglomerates with approved crushing strength for use in electric furnaces were smelted to produce alloys containing nickel; the agglomerates were characterized by scanning electron microscopy. The alloy obtained was metallic ferronickel with sulphide precipitates. Therefore, MHP pellets can be precursors of nickel alloys, which have to be refined to obtain the desirable composition.

Jul 6, 2020

By Beth Robinson

Central Mexico&apos;s mining districts, opened centuries ago during the Spanish conquest, still form the backbone of metal mining in the country today. Beginning at Chihuahua City, the Second Mexican Mining Rail Excursion traveled southeast from camp to camp through this major mining area to Taxco. Improved exploration, exploitation, and beneficiation methods have permitted continuous mining of many old deposits, and led to the discovery of new ones. Minerals not sought by early miners-lead, zinc, copper, and fluorite-now contribute substantially to mining activity in central Mexico. Of Mexico&apos;s five physiographic provinces, the rail excursion passed through two: the Mesa Central, and the Sierra Madre Occidental. The Mesa Central province is a wide tableland with basin and range topography, containing important base metal deposits. Mining in this region is primarily of limestone replacement ore bodies. Massive deposits form horizontal mantos or vertical chimneys. In northern Zacatecas, the Santa Eulalia and Naica mines demonstrated this character. The Sierra Madre Occidental lies west of Mesa Central in northern states, then widens to almost the entire width of the country from outside Mexico City to the southern border. The area consists of volcanic beds, several kilometers thick. These intermediate volcanics are primarily andesitic, of Tertiary age. Resting on older strata of adjoining physiographic divisions, the volcanic beds are overlain by a thick series of acidic flows and tuffs. Economic mineralization in the Sierra Madre Occidental is vein-type, primarily gold and silver. Mines at Fresnillo, Guanajuato, Pachuca, and Taxco contribute to the claim that this region is the center for precious metals in Mexico. A third type of mineralization, contact metamorphic deposits, is commercial at Santa Eulalia. First Stop, Santa Eulalia Mine tours began with the Santa Eulalia unit, located 25 km east of Chihuahua City. Mining in the region dates back to the early 1700s. The oxidation zone was worked until 1790, but mining declined until Asarco arrived in the early 1900s, building a selective flotation plant for treating primary sulfides. Asarco still owns 34% of Industrial Minera Mexico, S.A. (IMMSA), operator of the Santa Eulalia mine. Santa Eulalia currently has a milling capacity of 850 t/d. The San Antonio and Buena Tierra mines provide feedstock. Head grades at San Antonio, the mine participants toured, average 80-120 g/t of silver, 1.5-4.5% lead, 4-16% zinc, and 0.1-2.5% copper. Tin and vanadium were also recovered between 1930 and 1940. Estimated proven and probable reserves total about 7.6 Mt, although 1.8 Mt of reserves are located in areas of high water pressure and volume, which makes extraction difficult. Water is a significant production problem at the San Antonio mine. In one area, an AX drill hole encountered 2.6 m3/min (700 gal/min) at a pressure of 2.5 kPa. Precautions are taken to cope with the problem: protective drilling in advance of blasting is performed;

Jan 2, 1982

By Jim Owens

The methodology of quarrying changed significantly in the Indiana limestone industry in the 60 years between Sept. 11, 1941 and Sept. 11, 2001. The former was the date of the Pentagon groundbreaking ceremony, while the latter was when the building was damaged by American Airlines Flight 77. So too, though to a lesser degree, did the machinery and methods used to fabricate the stone. The rededication ceremony on Sept. 11, 2002 marked the end of the Phoenix Project, as the rebuilding effort was named. The story of this remarkable project illustrates what the American construction(and Indiana limestone) industry can accomplish when working toward a common goal.

Jan 1, 2005

By S. Mathur

Polyacrylic acid (P AA) was evaluated as a selective flocculant for dolomite-apatite system. P AA of 4 million MW was found to flocculate both dolomite and apatite. However, their flocculation behavior was significantly different with 450,000 MW PAA which was the lowest molecular weight fraction capable of flocculation. In single mineral tests, at a dosage of 2kg/t 90% of dolomite and 35% of apatite flocculated. Selectivity was achieved in mixed mineral tests where apatite of 90% grade at 70% recovery level was obtained in the concentrate from a feed consisting of 80:20 mixture of apatite and dolomite. The dolomite rejection was about 75% which corresponds to 1% MgO in the concentrate.

Jan 1, 1995

Overcasts are indispensible ventilation control devices to permit one airway to pass over another without mixing in room and pillar coal mining. The airflow distribution inside the overcast depends on its spe-cific configuration at which the flow enters into it. This study uses 3D numerical simulation to examine the pressure and velocity distributions inside an overcast. The effects of the overcast angle on the flow field are also examined. The flow is assumed to be turbulent and isothermal and the standard k-e model is utilized. Simulated results display flow separation and recirculation regions of different sizes occurring not only upstream and downstream from the overcast but also inside it. The results also show that the size of the recirculation regions in-creased with the increase in the angle before and after the overcast influencing significantly the flow field and pressure losses. The stream-lines are plotted to show the 3D structure of the flow field. The results from the simulation can guide overcast design commonly used in un-derground coal mines. Keywords: 3-D simulation, Overcast, Room and Pillar, Turbulence, Recirculation Region

Feb 27, 2013

By Brian Fulcher

In April 1997, Kiewit/Parsons Brinckerhoff (K/PB) completed the 7,600-m (25,000-ft) primary access tunnel for the Yucca Mountain, NV proposed high-level nuclear waste site. K/PB then began boring an exploratory east-west cross drift tunnel at the site. The 2,681-m (8,796-linear ft)East-West Cross Drift Tunnel was excavated through volcanic tuffs having zones of incompetent rock using a rebuilt Robbins 5-m (16.4-ft)hard-rock tunnel boring machine(TBM) with a special arrangement of supporting equipment. This portion of the Yucca Mountain project was completed in eight months.

Jan 1, 2000

By A. Wahab Khair, John G. Oldsen, John C. Stankus, Song Guo

During the last several years, implementation of trusses, in lieu of wood cribs, has been successful for supplemental tailgate support in the Pittsburgh seam. This paper reviews, the truss support system provided by the new high strength 0.6" tensioned cable truss, which is now also being used in cribless tailgates. Cable loading and roof deformation were monitored to evaluate roof and floor performance. The test results indicate that the cable truss system successfully controlled the roof and floor during the first and second panel extraction. This paper will describe the advantages of cable trusses and their load transfer mechanism as well as mine evaluation.

Feb 24, 1997

By G. L. Dollinger, J. P. Kindsvater, J. A. Gibson

DESIGN AND DEVELOPMENT OF A MOBILE MINING MACHINE INTRODUCTION Until recently, developing tunnels in hard rock has been accomplished either by the drill and blast method or by using large tunnel boring machines. Combining the flexibility of drill and blast with the safety, efficiency and productivity of a TBM has been the objective of mining machinery producers for many years. In 1979 The Robbins Company began developing a new type of tunnel boring machine called the Mobile Miner to meet these objectives. The development and testing of the Mobile Miner is the subject of this paper. CURRENT MINE DEVELOPMENT METHODS Both the drill and blast method and the use of a TBM have notable advantages and disadvantages. The drill and blast method, for example, allows much more flexibility, requires less setup time and has a lower initial cost than a TBM; however it requires the use of high explosives and blasting has a disrupting effect on the rock surrounding the development. A TBM, on the other hand, is safer to operate, more efficient, more productive and produces smooth tunnel walls without disturbing the surrounding rock. In longer straight drifts it will easily out distance the drill and blast method. The TBM, however, is limited to boring a circular cross section tunnel which must then be modified if a flat floor is required. It also has a higher initial cost and an extended setup period.

Jan 1, 1985

By C. Bise, A. Seal

Excessive noise has long been a hazard in the coal-mining industry. Studies conducted during both the mid-1970s and the mid-1990s consistently show that hearing hearing loss within the mining industry persists, in spite of regulatory requirements and sampling technology advances. When MSHA’s new health standards to protect miners from hearing loss took effect in September 2000, the potential developed to re-evaluate sampling approaches with regard to noise-source hazards, such as task-based methods. This paper describes results from a Penn State research project currently being conducted at an underground coal mine. Each occupation was reviewed, and a list of tasks or processes performed by each was generated. Traditional personal noise dosimetry, static sound pressure levels, and equipment sound mappings have been performed. Job tasks indicating the greatest levels of daily noise exposure and contributions to noise dose have been identified and will be discussed.

Jan 1, 2001

By Morris T. Worley

Editor’s note: Mining companies doing business in Central Asia, and parts of the developing world, should look for ways to promote community development through the introduction of appropriate technology. This article should be of interest to SME members. It shows sustainable development type projects need not be massive or expensive. Smaller, utilitarian projects are equally valuable to developing communities as they seek to develop their own economic and social infrastructures. Joint Development Associates International (JDA) began humanitarian relief and community development in Central Asia in 1992, following the collapse of the former Soviet Union. Appropriate technology has played an important role in the company’s efforts to assist those segments of society that are most vulnerable to poverty and disease.

Jan 1, 2005

By M. S. Miller

With prevailing assumptions that plentiful domestic coal reserves will be available for meeting our Nation’s expectations for on future low emission, coal-fired power plants, major government funding in Clean Coal Technology, and Carbon Sequestration Programs continues to be aggressive. However, after more than a decade of cutbacks in funding for domestic coal-related programs and personnel, there is a growing concern that adequate quantification and qualification of our Nation’s coal reserves is increasingly being compromised. This paper will define the growing concerns and dichotomies that continue to increase, and address the decreasing number of fossil fuel mapping and assessment programs by Federal and State programs.

Jan 1, 2004

By L. Maday, V. J. Perrone, M. B. Gilbert

INTRODUCTION The Brightwater conveyance system project in King County, Washington consists of constructing about 21 km (13 mile) of effluent and combined influent and effluent tunnels. The influent tunnels will collect sanitary sewerage from the service area and convey it to the new wastewater treatment plant (WTP) site at Route 9 in Woodinville, Snohomish County, Washington. The effluent tunnels will convey treated effluent from the WTP to an outfall at Puget Sound. The tunnels will be constructed primarily under residential areas, busy suburban roads and state highways. This 21 Km (13-mile) soft ground tunneling project faced many design challenges because of the geologic and hydrostatic conditions, long tunnel reaches, and large overburden depths. Boring depths typically varied from 45.7 M (150 ft) to 114 M(375 ft) with a maximum depth of 185.6 M (566 ft) deep. Conventional empirical methods for non-mountain terrain based on a 1:1 ratio of drilled footage per foot of tunnel bore (National Research Council, 1984) for evenly spaced borings provided a good start for the Phase 1 explorations. However a continuation of this approach with closer spacing was deemed inadequate by the geotechnical team for efficiently allocating geotechnical exploration resources for the final design. This paper presents a rational approach that was used to evaluate the value of a particular geotechnical exploration boring, pump test or other in-situ test. The method of analysis, which was initially developed for rock tunnels (Einstein et al., 1978), was modified for the Brightwater project. The method considers the potential construction cost risks resulting from variable geologic conditions, the cost and reliability of the geotechnical exploration and the earned value (cost risk reduction) of performing the geotechnical exploration. PROJECT DESCRIPTION In total the land portion of the conveyance system will include approximately21 Km (13 miles) of tunnels ranging in size from 3.0 to 5.2 M (10 to 17 ft) minimum inside diameter with overburden depths of 30.0 to 168 M (100 to 550 ft) and

Jan 1, 2005

By Edward DeLilla

For the past 30 years, surface mines have moved toward more highly mechanized, automatic systems that continuously mine overburden and ore to increase productivity, lower operating costs and minimize manpower needs. To achieve these goals, mine operators must be involved in every step of the machine procurement process. Several factors are involved in making the machines operate economically and efficiently: -Prudent engineering. -Proper planning. -Realistic feasibility studies. -Effective specification. -Thorough training of the mine personnel.

Jan 1, 1994

By W. Collingwood

As open pit mines continue to grow deeper and productivity continues to increase, the management of respirable dust and noxious gases can become a challenge. The natural wind flow in open pit mines is often recirculatory. This recirculation traps dust and gases in deep open pit mines. This problem is particularly acute in high latitude open pit mines due to a phenomenon known as an atmospheric inversion. In the winter, arctic and subarctic regions experience short days and long nights. This deficit of solar radiation creates a situation in which cold, still air accumulates near the bottom of the pit. In open pit mines, this can result in unhealthy accumulations of gases and other contaminants in the open pit mines. In this study, the natural wind flow patterns in and around open pit mines were investigated using a computational fluid dynamics (CFD) program. Two dimensional models were created for a variety of pit geometries. The effect of depth, slope angle, and wind speed on the recirculation pattern in the pit was examined.

Jan 1, 2011

By G. A. Calboreanu

One way of cost reduction is attained when using materials with improved erosion ? corrosion resistance. For many years hard irons successfully answered the Mining Operation needs however application ranges were limited due to the low chemical resistance of such alloys. Corrosion resistance of any hard iron increases when microscopically homogenizing chromium and generating passivation conditions throughout and between all metallographic phases. Chromium distribution of the new material called Max10 was analyzed with EDS ? energy dispersive spectroscopy. At critical depleted chromium carbide ? matrix interfaces chromium increased to 31.72% which is well within passivation levels. Generally the corrosion resistance of high chromium hard irons provided by Metal Casting Industry is limited to 0.5% sulfuric acid and 28 PPM ionic chlorides. Such restrains increased when using Max10 to 2.0% sulfuric acid and 100 PPM ionic chlorides. Max10 contains 35% carbide volume fraction, has excellent corrosion resistance within pH = 1.15 ? 13.6 while fracture toughness under plain - strain conditions and Mode I opening is KIC = 20 KSI.(inch)1/2. Wear rate was calculated with the pin-on-disk apparatus using a diamond indenter per ASTM G99 recommendation. After years of research, experimentation and implementation the Max10 castings were service installed in slurry pumps and mixing equipment. In some applications the life time of slurry pumps manufactured in Max10 tripled versus previously used materials.

Jan 1, 2012

By William R. Yernberg

The Fifth International Heavy Minerals Conference (HMC) was held Oct. 16-19, 2005, at the Marriott Sawgrass Resort in Ponte Vedra, FL. With SME as sponsor, the 2005 conference marked the first time that the HMC was held in North America. The conference is held every two years and provides an important forum for professionals in the heavy minerals and related industries to meet and discuss issues related to heavy mineral exploration, mining, processing and marketing. Previous locations included Australia and South Africa. The conference consisted of technical presentations, field trips to heavy mineral operations, a trade show and social activities. It was appropriate that Ponte Vedra was selected as the location for the conference. Ponte Vedra, located on the Atlantic Coast 17 km (10 miles) southeast of Jacksonville, FL, is the birthplace of heavy minerals mining in North America. Ponte Vedra beaches were mined from 1916 to 1929 in what was then called Mineral City. Though Ponte Vedra is now a golf and beach resort, there are still four heavy mineral mines operating within an hour’s drive. Today the Ponte Vedra Country Club and Golf Course is situated in the center of the former mining site.

Jan 1, 2006