Search Documents

By K. A. Stanley, N. A. Karl, D. R. Wilburn

"This summary of international mineral exploration activities for the year 2014 draws upon information from industry sources, published literature and specialists in the U.S. Geological Survey (USGS) National Minerals Information Center. The summary provides data on exploration budgets by region and mineral commodity, identifies significant mineral discoveries and areas of mineral exploration, discusses government programs affecting the mineral exploration industry and presents analyses of exploration activities performed by the mineral industry.Three types of information are reported and analyzed in this annual review of international exploration: 1) budgetary statistics expressed in U.S. current dollars provided by SNL Metals & Mining (SNL) of Charlottesville, VA; 2) regional and site-specific exploration activities that took place in 2014 as compiled by the USGS and 3) regional events that affected exploration activities including economic, social and political conditions, which were derived from published sources and discussions with USGS and industry specialists. Commodity and regional compilations are presented in this summary. Because multiple sources are used to develop these compilations, statistics may differ depending on the source and type of data that are being reported.The SNL data summarize planned company budgets for worldwide exploration activities in 2014 for 19 nonfuel mineral commodities based on company surveys. Research focused on precious metals (gold, platinum-group metals and silver), base metals (cobalt, copper, lead, molybdenum, nickel, tin and zinc), bulk commodities (iron ore, phosphate and potash), and specialty mineral commodities (diamond, lithium, niobium, rare-earth elements, tantalum and uranium). Information on uranium exploration activities was included for the first time in 2007. Data on lithium, niobium, phosphate, potash, rare-earth elements and tantalum were compiled for the first time in 2010 because of their increased significance. Since 1999, companies with exploration budgets of $100,000 and greater were included in the SNL compilations. SNL budget estimates exclude bauxite, coal and oil and gas. Exploration budget estimates for iron ore have been compiled since 2011 but reported separately. The 2014 SNL company survey is reported by SNL to cover an estimated 95 percent of the world’s nonferrous, nonfuel mineral exploration budgets. The 5 percent that is not covered includes companies that chose not to participate in the SNL survey, private companies that do not publish their budget data, and government-funded exploration activities"

Jan 1, 2014

By V. I. Lakshmanan, Dan A. Mackie

Traditional vat leaching methods have had limited success, primarily due to the high cost of loading and unloading the vats. In general, such batch methods are labor-intensive and costly. Heap leaching has emerged as a viable, low- cost alternative, but low recoveries, normally in the 70% range, offer opportunities for improvement. Also increased regulatory guidlelines for effluent and spent heap leach pads disposal offer potential for alternative methods. The Mackie Vat Leaching Jig (MVLJ) has had its incubation at Ortech International, where bench scale through pilot scale testing continues. Design developments and testwork over the past two years indicate that the time may be right for field trials.

Jan 1, 1990

By Yuting Xue

Classification of rock and coal is one preliminary problem for fully automated or intelligent mining. It assists in automated rib stability analysis and enables the shearer to adjust the drums without human intervention. This paper studies the classification of rock from coal on rib images using machine learning techniques. A database of rock and coal images was created by filtering photographs taken by NIOSH researchers during site visits. Machine learning was conducted on patches, smaller images randomly extracted from each rock or coal image. After training, the classifier was validated with the testing dataset and achieved an accuracy score of 0.9.

Jan 13, 2022

By M. E. Gershon

I would like to congratulate Professor Gershon on an idea that is obviously valuable and is certainly new to me. It has, however, to be further developed, in that one can get fallacious results by limiting oneself to positional weights. In the example problem, the positional weight of one block was 8.6 (the 8.0 value in the paper was incorrect) for 36 units in the cone, for a mean block value of 0.239. The positional weight of the second block was 4.4 for 15 units, for a mean block value of 0.293. Surely one would expect the second block to be rated higher. Additionally, the time value of money adjustment cannot be determined by depth, because the time that a block is mined is determined by the mining sequence, not depth. Figure 1 shows a slightly altered version of Professor Gershon’s pit. The overall value of the pit is the same, as are the total values under each of his blocks. The values in the right-hand cone have been reversed top to bottom, and the values in the rest of the pit adjusted to keep the central cone total unchanged. All values have been multiplied by 10. Figure 2 shows the sequence of mining, at three blocks per year, for Professor Gershon’s pit, and Fig. 3, the sequence for a pit under the other block. Table 1 shows the value and discounted value (157. ) of Professor Gershon’s pit, and Table 2 shows similar values for the second pit. It is apparent that the second pit schedule is more valuable than the first.

Jan 12, 1987

By Z. Yu

Low-rank/oxidized coals respond poorly to oil agglomeration. Emulsification of kerosene in the presence of surfactants dramatically reduces the size of the kerosene droplets. While this dramatically reduces the amount of oil that is required for efficient agglomeration (down to 0.25-0.5%), more importantly, the surfactants entirely change the electrokinetic properties of the oil droplets and thus the interaction between oil droplets and coal particles. Consequently, kerosene cationic emulsions can efficiently agglomerate oxidized coal particles. The agglomerates obtained in such a process can still be recovered by screening. Surfactants can affect fine coal filtration very profoundly when used to emulsify the oil which is utilized to agglomerate coal prior to its filtration. This sequence is much more logical than the use of flocculants - highly hydrophilic polymers - as filtration additives to aid dewatering of flotation concentrates. Although such polymers flocculate coal particles, they also render coal surfaces hydrophilic and make reduction of the cake moisture content difficult.

Jan 1, 2000

By Z. A. Md-Nor

Risk management is an established loss-control methodology that has been applied successfully in many industries. Recently, interest in this structured approach has grown in the mining industry. The main objective of this research was to develop a risk-assessment process, which is a part of risk management, that can be used by the U.S. mining industry to more thoroughly characterize risks associated with haul truck-related fatalities. The assessment is based on historical data obtained from the U.S. Mine Safety and Health Administration (MSHA) investigation reports, which includes 113 fatal incidents that occurred from 1995 through 2006. The risk-assessment process used in this research involves the following basic steps: identification of the risks, risk analysis and risk evaluation. The preliminary hazard assessment (PHA) method is used in identifying and quantifying risks. Risk levels are then developed using a pre-established risk matrix that ranks them according to probability and severity. The resulting assigned risk value can then be used to prioritize control strategies. This paper is a part of a detailed study on risk assessment for equipment-related fatalities in mining sponsored by the Western U.S. Mining Safety and Health Training and Translation Center.

Jan 1, 2008

By Juan J. Monsalve, Mario Karfakis, AMAN SONI, Nino Ripepi, Jim Hazzard

Pillar collapses are events that due to their severe consequences can be classified as high risk. The design of pillars in underground room-and-pillar operations should migrate to risk-based design approaches. The authors of this work proposed a risk-based pillar design methodology that integrates stochastic discrete element modeling for pillar strength estimation, and stochastic finite volume modeling (FVM) for stress estimation. This paper focuses on the stochastic FVM component for stress estimation. The mining and geomechanical aspects of a case study mine (CSM) are described and pillar stresses are estimated by using three approaches: (1) analytical solutions, (2) 2D finite element modeling, and (3) 3D finite volume modeling. This operation extracts a 30° dipping deposit, which makes current underground stone mine design guidelines inapplicable for this CSM. This work compares results from each stress estimation approach and discusses uses the point estimate method as a simplified stochastic approach to evaluate the effect of rock mass elastic properties variability on pillar stress distribution. Results from this work show that the three estimation approaches lead to different estimations, possibly, due to the wide range of assumptions each estimation approach considers. It was also determined that the horizontal to vertical stress ratio has a significant impact on pillar stress magnitude. Therefore, it is recommended to perform in situ stress measurements, or assume worst-case-scenario values to account and reduce uncertainty due to this parameter. The stochastic stress estimation approach used in this paper provides results that can integrate a risk-based pillar design framework.

Sep 24, 2022

Outokumpu Technology’s HSC Chemistry process calculation software enables the user to simulate an entire chemical or physical process. The HSC Chemistry 6.0 contains 21 calculation modules and 11 databases for reaction, equilibrium, heat balance, heat transfer, petrological and simulation applications. Most of the calculation modules automatically utilize the same extensive thermochemical database which contains enthalpy (H), entropy (S) and heat capacity (C) data. This database has been expanded to include more than 20,000 species.

Jan 1, 2007

By C. J. Burkhalter, H. Andrade, T. C. A. Gardner, J. P. Campbell

During the 1990’s several copper heap leach facilities treating crushed and agglomerated oxide and sulfide ore were constructed in South America. The majority of these facilities have been in operation for at least three years, during which time the operators have been able to monitor the performance of the heaps. The basis for the paper is a compilation of these operators’ experiences, leading to a discussion of the lessons learned over the past decade. Several key geotechnical issues are examined, focusing upon the integrity of the ore, drainage material and pipe network, along with the success of any inter-lift liners.

Jan 1, 2002

By Eric Eisold

The Wachovia Headquarters and Arts and Cultural Campus project in Charlotte, NC includes a 1.5 million square foot, 48-story office tower, two museums, an Afro-American cultural center and a 1,200 seat theater for the performing arts. Public access to the Cultural Campus is through two pedestrian tunnels constructed under city streets connecting to parking garages. The 5.7 m wide by 4.7 m high mined tunnels were procured through a design-build contract. The tunnels were designed as initial/final shotcrete linings with a sprayed water barrier sandwiched between layers of shotcrete. In addition, the mix design was supplemented with a cementitious admixture to develop internal water resistant properties in the shotcrete.

By E. Cho

Illinois No. 6 coals of IBC 101 and IBC 112 were treated in solution with sodium hypochlorite to remove their sulfur contents, especially organic sulfur. The lab experiments were conducted in two steps of leaching at room temperature and hydrolysis at 90oC. The removal of organic sulfur from IBC 101 was by 37.8% while that from IBC 112 was only 13.7% under their respective optimum conditions. This large difference in organic sulfur removal is considered to be due to difference in concentration of surface total acid group, 3.14 vs. 0.88 mmol/g of coal.

Jan 1, 2007

By F. N. Kissell, C. D. Litton

This study predicts the level of smoke that miners might meet while trying to escape a coal mine fire and describes how smoke would impede their safe escape. For this study, the authors assumed that miners exit through an escapeway adjacent to the burning entry, that some air would leak from the burning entry to the escapeway. The following conclusions were made: • A very low amount of air leakage to the escapeway can produce a critical level of visual obscurity from smoke. This shows that intake airways may be as susceptible to smoke visibility problems as return airways. • This critical level of smoke obscurity is reached much before a critical level of carbon monoxide is reached. • Small fires can cause a severe sensory irritation that further limits vision. Thus, reliable eye protection is very important. These results show that methods to guide miners through dense smoke will contribute greatly to saving lives during mine fires.

Jan 1, 1993

By E. M. Spokes

A.B. Rushton The work and resulting publications of the Committee on Underground Coal Mine Safety and The President's Commission on Coal were appropriate at the time of publication. The statistics cited in the publications appeared to be valid, and the actions proposed by the committee had merit. Although the actions proposed to achieve further improvements in safety may have been worthy of repeating, to associate statistics (Table 1) that are seven to eight years old with company names is bad. Statistics are readily available from the Mine Safety and Health Administration (MSHA) and are usually within three months of being up to date. A review of the most recent Coal Controlling Co. Report will reveal significant changes in the rankings. The more recent statistics should have been cited, or at least compared with those used in the article. Westmoreland Coal Co. is listed as having a 21.1 disabling injury rate for the period (1/78-12/80). The disabling injury rate for the Company for the year ending 1985 was 7.4 for the underground mines and 6.25 for the total facilities. Through March 1986, the disabling rate for the underground mines was 2.86. The management and employees of Westmoreland Coal Co. are committed to safety. The improvements achieved over the past five years attest to that commitment. We are justifiably proud of the achievement and dislike being misrepresented as in the April 1986 article. Reply by E.M. Spokes I regret that the lapse of time since the original work gives a picture of safety practice that is no longer true today. That Westmoreland has reduced its disabling injury rate by 65% to 7.4 in 1985 is most commendable, and I congratulate you for this accomplishment. It is typical of the progress sought by the National Academy of Science and National Research Council when they funded the original study and published "Toward Safer Underground Coal Mines" in 1982. If a significant number of companies do as well as Westmoreland, the report will have served its purpose. Since the paper was primarily a condensation of the original report, it would not have been appropriate to seek access to later statistics. The purpose in seeking its publication at the time of presentation was to reach those who might have missed the original report. The fact that publication was delayed has not voided that purpose and may have reminded some who were aware of the original that its recommendations still apply to improvement of underground coal mine safety.

Jan 6, 1986

By David R. Gossett

For the 22nd year, the chance to exchange knowledge, experience and business cards drew hundreds of mining and phosphate professionals for a two-day regional Phosphate Conference in Lakeland, Florida Nearly 400 people participated in the October conference, which focused on the phosphate industry?s future success. There were 41 exhibitors, 13 program advertisers and 23 sponsors among those supporting the conference. It was chaired by David Gossett, 2006-2007 SME Florida Section Chairman. In the opening panel session that he chaired, John Garlanger (SME) of Ardaman and Associates posed the questions; ?How successful has the industry been? How do we measure it and what factors contributed to the industry?s success? How long will the ethanol boom last? Can the industry obtain the permits it needs to mine for the next 30 years? Can the industry attract and retain the quality of workers it needs??

Jan 1, 2008

By W. J. Nokleberg, B. A. Bouley, T. K. Bundtzen

Central Alaska contains a wide variety of pre-, syn-, and post -accretionary mineral deposits that are related to the growth and evolution of the north-west North American continental margin. Withinpre-accretionary terranes, the Devonian-Carboniferous, carbonate platform-hosted MVT zinc-lead deposits of the Kandik and Reef Ridge districts in central Alaska, and the Devonian-Mississippian volcanogenic massive sulfide (VMS) polymetallic deposits of the Bonnifield, and Delta mineral belts of eastern Interior Alaska have received the most exploration interest to date. Syn-accretionary rift related, mafic and ultramafic sill swarms and zoned plutons of the Kluane-Nikolai igneous belt are currently being explored for Ni-Cu-Co-PGE deposits. Syn-accretionary granitoid complexes in the PurcellMountains, Illinois Creek, and Sitylemenkat areas have been explored for uranium-REE-gold, and tin-silver mineralization respectivelyPost-accretionary granitoid intrusions and associated volcanic fields that range in age from mid-Cretaceous to early Tertiary contain significant gold-silver-polymetallic resources in the East Central Alaska, Hogatza, and Kuskokwim Mineral belts. Collectively the three main post-accretionary plutonic/volcanic belts of central Alaska are part of the Tintina Gold Province, where exploration since 1990has identified about 848 tonnes gold.

Jan 1, 2000

By D. R. Nagaraj, Napoleon Tercero, Raymond Farinato

Historically, as for most reagents used in flotation, the wide-spread use of dialkyl dithiophosphinates as collectors in practical applications has preceded a detailed scientific understanding of how they work. Dialkyl dithiophosphinates are a technologically and commercially important class of collectors used in the flotation processing of Cu-Au, complex polymetallic, and precious metal ores. Plant usage has demonstrated that dithiophosphinates exhibit higher selectivity and flotation rates for Cu sulfides, galena, and precious metal values in the presence of other gangue sulfides, than the traditionally used collectors such as dialkyl dithiophosphates and xanthates. They also have an attractive health, safety, and environmental (HSE) profile. Although dithiophosphinates received little attention in the past in the flotation research community, recently, there has been significant interest in this chemistry, and numerous studies have been conducted to understand the fundamental interactions of dithiophosphinates with several base metal sulfides and precious metals. A critical overview of fundamental studies, laboratory ore flotation, and plant practice of dithiophosphinates is given in this paper. The findings from these studies are rationalized and explained by drawing on concepts and insights from coordination chemistry. A comparison between the interactions with various minerals and metals of dithiophosphinate and dithiophosphate analogues brings out some of the subtleties that seemingly minor changes in collector chemistry can make. The critical overview and analysis given here is useful in identifying gaps in knowledge regarding this important class of compounds. This in turn can provide a basis for the design of studies to advance our understanding of dithiophosphinate flotation performance.

By Martin Stone

Industrialized countries, particularly the United States and the United Kingdom, remain at the forefront of international efforts to control the potential disruption from computer malfunctions caused by the date change from1999 to 2000 — widely known as the millennium bug or Y2K. Disruption is least likely in the developed world, including the United States, Canada, western Europe, Japan and Australasia. However, the picture is potentially different in developing countries where many mining companies operate. The less developed the country, the greater the chance of some form of Y2K-linked disruption.

Jan 1, 1999

By H. Polat, Q. Hu, S. Chander

The collection efficiency of dust particles was determined in a laboratory dust chamber equipped with a water spray. Measurements were made in the presence of selected nonionic, cationic and anionic surfactants. For the nonionic and the anionic reagents, efficiency was maximum in a narrow range of concentration. The surfactant concentration corresponding to high collection efficiency was usually much below the commonly used concentration of l%, however. In comparison, much higher collection efficiency was observed for a cationic surfactant at extremely low concentrations. For delineating the mechanism of capture of dust particles, surface tension and contact angle results were used to obtain a correlation between the work of adhesion and the efficiency of collection. Such a correlation was reasonable for the nonionic surfactants but not for charged surfactants. In the latter case, electrostatic interactions between charged droplets and particles were more important, especially for the cationic reagent.

Jan 1, 1992

By J. A. Lombardi

Acid-Minesite-Solutions (AMS) are defined as copper-containing pit lake, tailing pond, acid-mine-drainage, and heap and waste dump irrigation solutions. All of these solutions are characterized by copper, acid and water contents that have value as individual commodities. HW Process Technologies, Inc. (HWPT) has developed nano- and hyper-filtration membrane methods for the separation of copper and other base metals, acid and water from AMS. These treatments are collectively called HWPT?s Engineered Membrane Separation® (EMS®) systems. The EMS® method of copper recovery produces small volumes of higher-concentration copper solution from large-volume, copper-dilute AMS. A case study of the 4,000 gpm Cananea EMS®-AMS plant for the recovery of copper from an acid-pit-lake resource is described. The EMS® method of copper removal from AMD and tails pond waters has been bench-scale demonstrated and are described, complete with projected budgetary capital and operating costs. Additional treatments for the recovery of sulfuric acid and high-quality water from the permeate (membrane passing) waters for the above-described AMS treatments are presented, with budgetary capital and operating cost estimates. [ ]

Jan 1, 2009

When it comes to processing industries, speed matters. More precisely, the faster/greater the throughput of finished product out the door, the more quickly money can flow back into the corporate coffers. In this quest for greater output, no processor can afford any weak links in the chain. Especially in the case of bulk solids operations, any one piece of equipment that slows the process down jeopardizes the profitability of the entire plant. However, one clay processor uncorked a pre-existing bottleneck by replacing its outdated separating equipment with a new design that immediately improved output.

Jan 1, 2007