Search Documents

By S. Shaw

There is an increasing requirement for mines to meet a certain minimum criteria for sustainability within the context of the physical environment, ecosystem and socio-economic system in which they are located. The mining industry has wrestled to develop methods for assessing the ‘sustainability’ value of a mining project and indicators of ‘sustainability success’. A methodology for the evaluation of sustainability of a mining project using the Multiple Accounts Analysis (MAA) system was developed. The MAA is a platform for engagement of stakeholders and for the assessment of site-specific alternatives based on both qualitative and quantitative indicators of success.

Jan 1, 2004

By C. Demir, M. S. Celik, I. Gülgonul

Na-feldspar (albite) and K-feldspar (microcline or orthoclase) are major feldspar minerals with identical crystal structures and physicochemical properties. Flotation appears to be a unique method of separating these minerals. Fundamental studies on amine/feldspar system in the presence of monovalent salts showed that separation of these feldspar minerals by flotation is possible at certain concentration of monovalent salts in HF medium and natural pH. A comparison between natural pH and HF medium indicates that the latter provides a better selectivity at the expense of higher collector requirement. A general mechanism for both systems involving an ion exchange between the uncommon ions and adsorption of the common ions is proposed to be responsible for creating differences in the charge of albite and microcline unto which amine adsorbs.

Jan 1, 2002

By H. K. Lin

The effect of metallic iron fines on froth flotation of a sulfide ore was examined by comparing the flotation results with and without iron fines present in the flotation feed. Mild steel and ceramic laboratory ball mills were used to grind 600 g sulfide ore charges. The mild steel ball mill generated approximately 4.6 g of iron fines (0.8% of the ore charge mass) when grinding to a product size of 80% passing 200 mesh (75 mm). When a low dosage of a weak xanthate collector was used in flotation, the impact of the iron fines on sulfide flotation was marked. Higher dosages of stronger xanthate collectors rendered the impact of the iron fines much less significant. Consumption of the collectors by the powdery iron fines is believed to cause the differences observed in the flotation results. A galvanic effect on flotation was not evident in this study. The impact of the iron fines on silicates depression was also examined.

Jan 1, 2008

By W. F. McDermott

The transportation of solids by pipeline is not new. In 1891 a United States patent broadly covering a method of pumping coal with water was granted to W. C. Andrews. His pilot plant was constructed on what is now the site of the New York Public Library in Manhattan. His process was applied to pumping coal mine waste back into the worked out portion of coal mines. On October 26, 1967, the world's first long distance iron ore slurry line was put into service by Savage River Mines. The commissioning of this 5.0 million dollar installation climaxed three years of development, testing, and construction and proved the Company's faith in pioneering this unique transportation method for iron ore. This paper will discuss some of the more pertinent items in connection with that three- year period. Also to be discussed will be the operation of this line during the past eleven months.

Jan 1, 1968

By Ravi Ray, Kostas Kaklis, Zach Agioutantis

"Modern underground mining is becoming more complex and geotechnically challenging. The engineer uses numerical, analytical, and data-driven methods (empirical and/or experimental) or their combination to overcome these challenges. Each method has its advantages and disadvantages. Nevertheless, given the amount of innovation and experience involved in developing each of these techniques, it will be prudent to use all their benefits rather than favoring one technique over the other. Pillars are the most important support element in an underground mine. A holistic geo-mechanical solution needs to be determined to design mine pillars using a proper sequence and exact mix of the three methods. A combination of these methods, in sync, can encompass the several advantages of the three methods while eliminating their disadvantages. This paper presents a conceptual three-tier solution to the pillar design problem, to improve its design pedigree, using a proper combination of numerical, analytical, and data-driven methods. At the focus of this proposed method lies the Ground Reaction Curve (GRC) concept.INTRODUCTIONAlthough the stability analysis of underground excavations is a challenging problem, its understanding has improved tremendously over recent years through the use of improved tools and techniques. The trial and error method was replaced with more scientific methods like the empirical and analytical methods that are still in use today. Empirical methods were developed based on large data sets obtained from experiments and observations (e.g., coal pillar strength equations). Analytical methods were developed based on mechanical understanding of stability (e.g., safety factor for vertical pillar loading, Convergence Confinement Method). Improvement in computing power and numerical techniques led to the development of several numerical methods (e.g., finite difference, finite element) suitable for geo-mechanical analysis.Each of these methods have certain advantages and limitations. Nevertheless, the user is often puzzled over the proper method selection and over the proper sequence of using them. This exercise becomes more challenging when different methods are combined, where, for example, one has to estimate the pillar strength based on empirical equations (e.g., Mark-Bieniawski coal pillar strength equation), determine the factor of safety based on an analytical approach (e.g., tributary area load divided by pillar strength), and analyze pillar-strata interactions using numerical analysis (see Esterhuizen, Mark, and Murphy, 2010b).Challenges increase when current pillar design methods are designed as passive structures to balance the fixed dead weight of the overburden. This classic suspension design approach does not recognize the self-stabilizing capacity of the overburden (Frith and Reed, 2018). A practical solution to address these issues is the use of numerical analysis. However, one should always keep in mind that the numerical modelling approach may have certain practical limitations."

Jan 1, 2019

By William R. Yernberg

The combined 79th Annual Minnesota Section of SME Meeting and 67th Annual University of Minnesota Mining Symposium was held April 11 and 12, 2006, in Duluth, MN. About 300 mining professionals attended, including engineers, executives, mining managers and suppliers, from throughout the United States and Canada. This year’s theme was “Success in the New World of Mining.” The SME Minnesota Section meeting included a keynote session, a special projects update, a general managers update and technical paper presentations. The University of Minnesota Mining Symposium program featured a panel discussion on Minnesota’s relationship with China. The combined meeting included a trade-show consisting of 64 booth spaces. Tradeshow demand exceeded expectations, and an additional 10 booth spaces were added in the registration lobby. Also included were an SME short course on pump basics and social events.

Jan 1, 2006

By R. C. Bratton, R. Q. Honaker

Hindered-bed separators are recognized as low-cost, high-capacity devices for both classification and density separation; however, since their inception, there have been few significant advances in the fundamental technology. Recently, Eriez has shown through modeling and pilot-scale testing that the innovative approach to feed presentation offered in the CrossFlow teeter-bed separator provides improved metallurgy when compared to traditional hindered-bed classifiers or single-stage coal spirals. This design feature prevents excess water from entering the separation chamber and disrupting the overall fluidization flow rate within the teeter zone. Most recently, a side-by-side industrial scale evaluation has verified that this technology improves overall efficiency and simultaneously reduces the separation cut-point. With regards to coal processing, data from full-scale units indicate that the CrossFlow offers good separation efficiency, high unit capacity, and metallurgical results consistent with laboratory- and pilot-scale separators.

Jan 1, 2006

By Tim O’Neil

If you build a big truck, build a big tire to match it. Let that haulage synergy aid the economics, productivity and lessened maintenance for the unit. Now, Cater-pillar and Michelin have done just that. Discussions began in 1996. Caterpillar was making plans for its 797 ultra-class haul truck. The development team realized the need for a tire that could withstand extreme loads. The 797 would weigh 558 t (615 st) and be capable of 64 km/h (40 mph) speeds. So Caterpillar approached Michelin. The two companies realized the benefits of jointly developing a tire for the 797.

Jan 1, 2002

By H. Haselhuhn

Filtration of hematite ore slurries can be a bottleneck in some hematite processing plants due to inadequate filtration rates caused by the dispersion of fine particles. Flocculation of fine particles in the slurry decreases the specific cake resistance of the filter cake allowing for increased filtration rates. CO2 sparging of hematite slurry was shown to increase the filtration rate by altering the pH and the surface chemistry of the particles. It was shown that an increase in filtration rate of 278% can be accomplished by lowering the pH from 11 to 6.5 using CO2. This was attributed to increased flocculation of hematite and silica particles in the ore.

Jan 1, 2012

By N. Chow

The recovery of manganese from lower grade resources has been studied for a number of years. Of key importance of prior work, was the discovery that higher valent manganese resource can be readily leached with sulfurous acid. This eliminates the need for high temperature reduction roasting that is conventionally used in processing high grade material. High temperature roasting is energy intensive, emits a large amount of carbon dioxide, and would not be economical for processing lower grade material. While the prior work provides important information to extract manganese from lower grade resources, the production of unwanted by-products, and high water and energy usage has limited its commercial use. This paper describes the results from laboratory work that demonstrate solutions to problems, which to this point preclude commercial development. Preliminary mass and energy balances show that a significant opportunity exists in producing manganese with this hydrometallurgical scheme in a low cost, environmentally friendly manner. Emphasis of the work is on low water use, low overall energy use and economic destruction of unwanted by-products.

Jan 1, 2011

The OptiPit® software program is developed based on expertise gained at the Colorado School of Mines (CSM) using Mixed Integer Linear Programming (MILP) techniques. This program has been developed to satisfy the need in the mining industry for a multi-time period schedule and cutoff grade optimization tool that handles large scale open pit and underground mining operations involving many dumps, stockpiles, complex processing options and blending requirements. The current software (or earlier development versions) has been beta tested and used on various large scale projects within Placer Dome Inc., Newmont Mining Corporation, and Phelps Dodge Corporation since 2003. Through the use of this software, these companies experienced additional value creation by optimizing mine sequences, cutoff grades, material process flows and stockpiles under complex operational and processing constraints. This paper will present simple case study results to demonstrate the power of OptiPit® when used as a cutoff grade optimization tool. Furthermore, the paper will show, by example, how significant the difference in the Net Present Value (NPV) of a given project can be, depending on whether results are obtained by way of cutoff grade optimization using OptiPit®, or by using traditional breakeven cutoff grade approach.

Jan 1, 2007

U.S. Borax’s mine in California’s Mojave Desert is the source of nearly half the world’s supply of refined borates. These minerals are used in hundreds of products, including essential plant nutrients that increase crop yield and quality, and safe building products that protect homes from insects and the elements. Borax’s workforce is also safe. In fact, it is among the safest in the nation. In 2003, the company was recognized by the U.S. Mine, Safety and Health Administration (MSHA) for achieving the best safety record among large U.S. mining operations. It was also recognized by its parent company, Rio Tinto, for achieving the best record among its nearly 80 worldwide mining operations. Borax’s safety performance is five times better than the national average. And its workforce recently achieved more than two million hours without a lost-time injury.

Jan 1, 2004

By J. Darlington, A. K. SenGupta

Water-swellable layered silicates, namely, the smectite clays can remove suspended materials (called herein as debris) and metal ions from aqueous streams. The present study shows that the flocculating and metal extracting abilities of smectite clay-based flocculants can be enhanced when these clays are used in conjunction with a specific anionic polymer. Such performance enhancement is attributed to the following: i) the clay-dispersing ability of the polymeric additive, that would translate into an increase in the clay-surface area available for the attachment of the debris particles onto the clay particles; ii) the possibility of dispersant-to-coagulant transition of the polymer during the later instants of the treatment process, as a result of reduction in solvency of the wastewater for the polymer due to the release of cationic species from the clay-based flocculant solids; iii) metal-complexing ability and adsorption properties of the polymer.

Jan 1, 2002

By M. van Elp, R. Saitua Nistal, P. J. M. Groot

Demand for construction raw materials depends on investment in housing, other buildings and infrastructure. The provision of these materials requires early knowledge of future trends in construction investment. By using scenarios possible future developments and bandwidths can be explored. Policy makers in government organisations as well as in the private sector can base their policy decisions upon these insights. In this paper we discuss the case of sand and gravel in the Netherlands. We will show that, depending on the future role of government and the degree of internationalisation, the long term demand for construction raw materials will strongly diverge. Nevertheless there are some common developments such as a decreasing population growth, a smaller share of the labour force in total population and a growing wealth. In different scenarios we will encounter different conditions for minerals provision and for sustainable development.

Jan 1, 2011

By Maurice Grieves

GC. Waterman Mr. Grieves' paper on "Shaft Sinking Today--A Boring Business Tomorrow" in the Dec. 1981 issue of MINING ENGINEERING is an excellent description of recent improvements in speed and costs of shaft sinking. However, shaft boring techniques are not a recent development. In 1935-36, the Idaho Maryland Co. (gold), Grass Valley, CA, bored the vertical 1.5-m-diam Idaho No. 2 ventilation and supply shaft to a depth of 346 m. The equipment was designed and perfected by Branner Newsome and was, I believe, described in "Transactions." Pickands Mather later bored a 1.8-m-diam shaft to a depth of about 305 m using Newsome's design. The Idaho No. 2 shaft cut through hard gabbro, diabase dikes, soft serpentine, very incompetent ankeritized serpentine and a strong fault zone. The completed shaft did not require timber support; the fault zone was cemented. Equipment consisted of a rotating 1.5-m or 3-m core barrel with a slotted bottom which cut a 76-mm kerf. The cutting agent was chilled steel shot introduced into the slot as needed. The driving mechanism and core barrel were lowered into the shaft, the former secured to the wall and the inshaft "engineer" operated the motors which controlled core barrel rpm and advance. After an advance of 1.5-3 m the equipment was lifted out of the shaft, a half(?) stick of powder cut off the drilled core, and it was hoisted to the surface with a cable attached to an eye bolt at the tope of the core. A "shift" consisted of three men: hoistman, equipment operator (down the shaft), and a surface laborer. Advance was variable as equipment and techniques were perfected. Near the end of the job advance was, as I remember, 1.5-3 m per shift. Costs were, as I recall, about $115/m. Up to 4 m cores were lifted out in one piece and swung to the dump by a stiff leg derrick. The Newsome equipment was relatively inexpensive to build and operate and his method should be (more than?) competetive with the methods described by Grieves. W.E. Hawes The author, in mentioning the South African developments of the cactus grab, ignores the parallel development of the Cryderman mucker in this hemisphere. Perhaps a slightly longer history of blind hold drilling would have been in order. Blind shaft boring got a major boost at the Nevada Test Site, as part of the nuclear weapons development, when it was essential to be able to quickly assess depth for weapons testing. One of the early civilian attempts to utilize this technology occurred when Kerr McGee drilled the shaft at the Section 19 Mine at Ambrosia Lake, NM. This twin masted drill rig belonged to a subsidiary of Kerr McGee, not Shaft Drillers. This was a difficult hole, due to bentonitic shales that decomposed. Later advances in drilling fluids eliminated this problem. The Conoco project referred to is not entirely correct, and needs minor amplification: The depth of the development (not pilot) shaft drilled was 684 m, at a diameter of 3.05 m, with a 2.16 m ID hydratatic casing being installed to a depth of 669 m. Conoco Inc., not Challenger, executed the drilling, however Conoco did use Challenger Drilling Company's Rig 14-S. Rig 14-S is unique in that it is specifically designed for shaft drilling, rather than being an oil field rig used for this service. All work was planned and directed by Conoco personnel. Deviation of the aforementioned shaft from vertical was 31 cm. Two smaller shafts (pilot shafts) were drilled with the same rig. These smaller ones were drilled 1.8 m in diameter, to depth of 665 m and cased with .91-m-diam casing, to depth of 650 m to be used as pilot holes for 5.5 m diameter shafts. The total elapsed time for all drilling, casing, cementing, and rig moves was 50 weeks. The constraints mentioned of vertical accuracy, torque, wall collapse, rig set up time, lining time etc., pumping out, etc., may not be as serious as the author implies. First, vertical accuracy: The record achieved by Conoco indicates that with reasonable care, good accuracy can be obtained, primarily by having a fair amount of weight in tension, rather than on the drill bit. Second, the amount of torque that can be applied to the drill stem has been greatly increased by the introduction of larger diameter drill stems, such as the new Hughes rig uses. Third, risk of collapse of shaft walls is minimal with the proper mud program. Basically, the walls are supported by the weight of the mud and it is not removed until some type of casing is installed and grouted in. Here in the real challenge of blind drilling shafts to devise a more economical method of lining bored shafts than using steel casing. The remaining issues were minor at Conoco, provided adequate planning and scheduling takes place. An excellent paper, "Shaft Drilling--Crownpoint Project" by Hassell H. Hunter, presented at the Fifth Uranium Symposium in Albuquerque in Sept. 1981 contains details of this project. A combination of blind boring, with enlargement by either mechanical means (boring machine, or tunneling type shield) or slabbing down, with muck removal through a larger bored shaft would seem to be the future trend in shaft development. The economics, especially for wet conditions, favor this concept over conventional sinking, as has been demonstrated at Kerr McGee --Churchrock, UNC--Churchrock and Conoco at Crownpoint.

Jan 3, 1983

By Ivo Dreiseitl, Kondratenko. Anatoly

"The second prime area within the Interoceanmetal Joint Organization exploration area named H22 was delineated in 2013 with the goal to ensure sufficient nodule reserves for profitable mining operations and processing.The knowledge base for area H22 has been obtained from archive materials. The geological situation can be characterized as follows: the sea bottom is represented by tectonic blocks oriented in a sub-meridional direction. According to swath mapping, the depressions (troughs) are contoured at depths of 4500-4600 m while the tops of horsts occur at 4300-4350 m. Volcanic relief occupies 6% of the H22 area; in the eastern part a multicone volcano was detected. Its area at the base is 153 km2. The maximum height of a cone above the base is 850 m. The crystalline basement composed by tholeiitic basalts of late Oligocene age is covered by about 100 m of sediments. Semi-consolidated to consolidated calcareous nanofossil sediments of the Marquesas formation are deposited on the basement. Higher up in the profile sediments of the Clipperton formation occur. They are represented by unconsolidated siliceous (Radiolaria, Diatom) ooze. Sediments containing calcium carbonate have not been detected. Where opaline silica (or CaCO3 if any) content is below 5%, the sediments belong to zeolitic clays or red pelagic clays. Grain size composition of the seabed and the near-seabed sediments in H22 classifies them into clayey silts."

Sep 1, 2014

By R. P. Sloan, A. S. Whitford

In November 1999, CCI's Empire Iron Mining Partnership and MinnovEX Technologies Inc. developed an expert system for advanced control of their Empire IV Grinding Section. Empire IV is comprised of three autogenous Primary Mills and six autogenous Pebble Mills, with a single Pebble Crusher and high pressure Roll Press. The challenges of controlling and optimizing three distinct grinding lines that are inter-woven by a pebble crushing circuit were met with innovative and unique solutions. This paper will detail the approach employed at Empire and will focus on the aspects that make this application unique.

Jan 1, 2001

By T. Hudaverdi

Control of the particle size distribution of a muckpile after blasting is always an important subject for mining industry. Blasting has a significant impact on downstream processes such as loading, crushing and grinding. Improvement of blasting results provides increase in loader and excavator productivity due to increased diggability capacity, and increased bucket and truck fill factors. Suitable and uniform particle size distribution results increase in crusher and mill throughput and decrease in energy consumption in size reduction process. Digital image analysis technique has been used for many years in mining industry in order to determine blast fragmentation. The images of muckpile surface can be used to determine the mean fragment size (x50). The source of digital images can also be haul truck, leach pile, waste dump, stockpile, and conveyor belt. The screening that is conventional method to measure blast fragmentation is time consuming and expensive. Digital image analysis is a cost effective and faster method (1).

Jan 1, 2012

By Rafael C. Castro

As part of its risk management plan, the South Central Connecticut Regional Water Authority (RWA) is assessing the condition of its system of raw water conveyance tunnels and connecting pipelines. In 2006, the RWA inspected one of the system?s main tunnels, a 4-mi, 1950s-era tunnel that had not been inspected since its construction. The inspection team prepared extensively for the unknown conditions in the tunnel, and the inspection was completed safely and successfully. This paper describes the team?s pre-entry preparations, dewatering and ventilation efforts, surface-to-tunnel communication, access, physical inspection of the tunnel, and the lessons learned throughout the process. Additionally, this paper will preview planning for the subsequent inspections.

Jan 1, 2008

By E. R. Spencer

National Institute for Occupational Safety and Health (NIOSH) researchers conducted an investigation to quantify sound levels and to determine the amount of sound reduction provided by engineering noise controls installed in a talc processing plant. Baseline sound level and sound intensity measurements were performed at the plant and the measurement locations were recorded for comparison to post-control measurements. Follow-up measurements were then made at the same locations after the initial noise controls were installed. The plant subsequently decided to implement additional noise controls and the researchers returned to conduct measurements for a final analysis of all noise controls. The most significant results showed a sound level reduction in the main mill area from a range of 93-104 dB(A) down to 90-94 dB(A), and a total sound power level reduction of 21 dB(A) for air classifying mill 3.

Jan 1, 2008