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By D. Komljenovic, V. Kecojevic

Selection of the best possible truck type (model) is of crucial importance for the mine decision-makers. In this paper, authors contribute to the body of knowledge by developing a novel methodology for the selection of mining truck. Both the Coefficient of Technical Level (CTL) and Analytic Hierarchy Process (AHP) methods were used in this study. The CTL represents a mathematical function which takes into consideration the interrelations among the main technical parameters of mining trucks. The authors developed a hierarchical structure where both attribute categories and their importance, i.e. priority or weight in the selection process were determined. For each category, a number of sub-attributes and their priorities were assigned, and a pairwise comparison among them was performed using the AHP method. In the final part of the study, the CTL was integrated into the AHP and represents a holistic approach in the selection of mining trucks. A case study on 180 tonnes truck category offered by five manufacturers was carried out. A sensitivity study of obtained results was also performed indicating a very stable solution. The methodology presented in this paper may be used by mining operators to help in the selection of a specific type when acquiring a new truck. It may also be used by equipment manufacturers to help in analysis of potential benefits of envisaged modifications concerning an existing truck type and/or development of a new type.

Jan 1, 2007

A clay binding agent has been investigated to enhance flotation recovery of bitumen from Canadian high fines oil sand in the Clark Hot Water Extraction (CHWE) process. Selective adsorption on fine particles and subsequent agglomeration are critical for the success of clay binder enhanced oil sand flotation. A number of flotation tests have been performed at different reagent dosages under different operating conditions such as pulp pH to evaluate the reagent performance. Dissipative Quartz Crystal Microbalance (QCM-D) analyses of clay binder adsorption on quartz were carried out to better understand process mechanisms. It has been found that use of clay binder in flotation resulted in an absolute bitumen recovery increase of 18%, 25%, and 11% for the high-, medium-, and low-grade oil sand samples, respectively. The QCM-D analyses have revealed that the clay binder was strongly adsorbed on the SiO2 surface.

Jan 1, 2012

New developments in the pipe conveyor and belt are advanced to address the growth in the capacity, length and complexity of pipe conveyor systems. Improved belt construction can offer better stability during horizontal curves and resistance to twist. Low rolling resistance rubber compound can significantly lower the power consumption and belt tension, producing capital and operation cost savings. Dynamic analysis, when used to analyze the conveyor?s starting and stopping behavior, can improve the design and reliability of long overland pipe conveyor systems. For these three aspects, technical backgrounds and field installations as examples are discussed in this paper.

Jan 1, 2012

By H. Ipek

Industrial grinding machines used in the mineral processing industries are mostly of the tumbling mill type. These mills exist in various types: ball, rod, pebble, autogenous, and semi-autogenous. Balls and rods are traditionally media shapes used in the tumbling mills. In resent years, as an alternative to balls, grinding charges with various shapes are being used. Cylpebs are slightly tapered cylindrical grinding charges with length equaling diameter, and all the edges being radiused. Cylpebs of equal diameter and length have 50% greater surface area and 45% greater weight than balls of the same material. In addition, they have 9% higher bulk density than steel balls, or 12% higher bulk density than cast balls. An important advantage of cylpebs over balls is that cylpebs produce narrower granulometric distribution due to their shapes. However, some discrepancies were found in the literature regarding the milling performance of cylpebs in comparison with balls (Chi, 2004). In recent studies, Chi (2004) has provided detailed information on cylpebs and has compared these to balls in relation to media mass, size distribution, surface area, and input specific energy. Ipek (2006) has investigated the effects of cylpebs and balls with equal mass and surface area on the breakage rate of quartz, using cylpebs and balls separately. Similarly, Lameck and Moys (2006) have investigated the effects of balls and worn balls on breakage rate of material using worn balls as grinding environment. However, no study has attempted to investigate the effects of grinding environment other than balls on the brekage distribution. As indicated by Prasher (1987), the breakage distribution function is independent of the following variables in ball mills: hold-up (Mika et al., 1967; Kelsall et al. 1969), mill speed and ball load (Herbst and Fuerstenau, 1972), media load and ball density (Kelsall et al., 1973), mill diameter (Malghan and Fuerstenau, 1976), and powder charge (Shoji et al. 1980). The aim of the present paper is to compare the effects of cylpebs and balls on the breakage distribution function of quartz with respect to same mass and same surface area. BACKGROUND Comminution as a rate process is called kinetic approach. Studies on the kinetic approach are reviewed by Oner (2001). Oner states that grinding kinetics are based on studies by Kolmogorov in 1941 and that Robert (1950) is the first to suggest this approach. Later, Melzak, Loeveday, and Reid have improved the grinding kinetics equation; and, Austin and Lynch have conducted two basic studies on the analytical solutions of these equations. Considering the results of studies comparing the size reduction mechanisms, it has been accepted that breakage constitutes of two operations. These two basic operations, first defined by Epstein (1948), are those of selection of material for breakage and the distribution of breakage material to particle sizes smaller than the initial size (Lynch, 1977). Epstein defined the two operations as: ? Pn(y), the probability of breakage of a particle size in the nth step of the breakage process. ? F(x,y), the cumulative distributions by weight of particles of size x<y arising from the breakage of a unit mass of a size y. Probability of breakage is called a selection or a breakage-rate function (Si). Characteristics size distribution after breakage is called a breakage distribution or appearance function (Bi,j). Due to the difficulties in representing particle size distributions mathematically and constantly, the batch equation based on particle size fraction is suggested. Thus, as is the case in breakage distribution and specific rate of breakage, the breakage parameters were defined by batch grinding experiments conducted in laboratories (Oner, 2001). When effective breakage occurs in the mill, the breakage of material with single feed size fraction usually fits first order grinding kinetics and the specific rate of breakage values can be calculated through the slope of semi-log plot. The values of the breakage distributions are deduced from the size distributions at short grinding times where there is mainly size 1 material breaking and only small amount of smaller sizes to rebreak (Austin et. al., 1984). B values can be calculated by using BII. [ ] where j is the top size of the charge, Pi(t) is the cumulative percent undersize of i th size interval at the short grinding time which gives no more than about 30% broken out of the top size interval. Cumulative primary breakage distribution, Bi,j, is also defined in an empirical form by [ ] where xi is the top size and Bi,j is the weight fraction of primary breakage products. The parameters F, ? and ß define the size distribution of the material being ground. On plotting size versus Bi,j on log scale, the slope of the lower portion of the curve gives the value of ?, the slope of the upper portion of the curve gives the value of ß, and F is the intercept as in Fig.1. [ ]

Jan 1, 2009

By Jack Magtoto, Lysa Voight, Tom Martin, John Forero

SUMMARY Commitment by all parties to partnering goals established early in the contract aided Affholder, Inc. in constructing 2,360m (7,700&apos;) of soft ground tunnel in Rancho Cordova, CA. Despite two zones of known contamination, encountering a zone of loose cobbles and boulders in a matrix of flowing sand, some perched water tables and a flooded tunnel after 2 upstream safety plugs failed, the Contractor finished the work 33 days early and only 1.91% over his original bid.

Jan 1, 2007

By Hemang Desai

A damaged outlet pipe beneath Lenihan Dam has restricted reservoir discharges, severely constraining the owner?s groundwater recharge program. The solution, a new outlet pipeline through the dam?s right abutment, includes an approximately12.2-m-deep (40-ft-deep) shaft and 618.7-m-long, 4.3-m-diameter (2,030-ft long, 14-ft-diameter) tunnel mined in Franciscan melange composed of hard blocks of rock and soft clayey matrix. Alternating road header with drill and blast operations and using steel ribs and shotcrete have proven a flexible combination for handling the variable ground conditions. Excavating the shaft and connecting it to the tunnel require lowering the reservoir for five months, during which time careful construction sequencing and use of a tunnel plug eliminate the risk of an uncontrolled discharge.

By Ö. Kaya

The removal of gangue minerals from three different graphite ores (Inebolu, Akdag?madeni and Çoraklidere) from Turkey by acid leaching was studied. Acid leaching experiments were applied to the flotation bulk concentrates, which were obtained in determined optimum conditions after preliminary flotation tests. The effects of acid type, acid concentration, leaching temperature and leaching time on the dissolution of gangue minerals were studied. The most suitable leaching conditions were determined to be 20% HCl + 4% HF for acid type and concentration, 85 ºC for leaching temperature and 4 hours for leaching time. After removing the gangue minerals at these optimum conditions, the total carbon contents of the samples from Inebolu, Akdag?madeni and Çoraklidere increased from 23.51% to 40.07%, from 37.93 to 60.47% and from 42.28 to 59.47%, respectively.

Jan 1, 2009

By K. Oraee

Zarshuran gold deposit, with the total reserves of some 12.5 million tons of 4.18 g/ton ore, is considered to be an important gold mining project in the area. In this paper the feasibility studies of the whole project is carried out on the basis of several economic variables. Given that mining data are often of uncertain nature, these economic variables have therefore been estimated under the conditions of uncertainty. The resultant Net Present Value is hence also obtained under the same conditions. For this purpose, a model is first devised with the help of Excel and COMFAR software. The model is then developed that considers different scenarios which would result in different expected values for the economic variables. It is concluded that the NPV of the project is most sensitive to gold and silver price and that other variables such as discount rate, operating and capital cost all affect the feasibility of the project with lower degree of severity. Finally, risk analysis is also carried out using Mont Carlo technique, in order to estimate the most probable value of NPV. The average NPV calculated in this way is US$ 49.7 Million, whilst without due consideration of risk, this would be US$ 36.6 Million. The techniques used, together with the procedures adopted in this paper, can be used in feasibility studies of all mining projects. Such decision would result in more accurate Net Present Values than expected from other frequently used methods.

Jan 1, 2011

By D. L. Ogonowski, J. O. Marsden

The Candelaria copper-gold mine is located approximately 25 km south and east of Copiapo in Region III, Chile. The original concentrator was designed to treat 28,000 t/d (30,800 stpd) of chalcopyrite-bearing ore through a circuit consisting of a single 11.0 m(36 ft) diameter SAG mill, two ball mills, conventional rougher and scavenger flotation, column cell cleaner flotation, and ceramic disc filtration. The plant was commissioned in August 1994 and quickly reached design capacity and expected levels of metallurgical performance. In May 1996, a decision was made to double the capacity of the concentrator by the addition of a second line of equipment. The expanded facilities were commissioned in October 1997, less than 18 months after the decision to proceed, and well within the budget. The original concentrator facilities were replicated or duplicated as much as possible, however, a number of important equipment changes were made to take advantage of industry developments since the original concentrator was designed. These included the use of Eimco 120 m3 (4,200 ft3) cells for rougher and scavenger flotation and the installation of a Svedala VTM-800Vertimill for regrinding. This paper describes the rationale behind these changes and explores the reasons for the success of the project.

Jan 1, 1999

By C. E. T. White

Although trace amounts of Indium are found in many ores, commercial production of the metal has come almost exclusively from residues, flue dusts and slags generated by Zinc recovery operations. Our paper attempts to summarize the various approaches used to recover Indium from these by-products. Some comments on production and price trends are included as well as our views on future availability.

Jan 1, 1982

By E. A. Metz

Perfect combustion in an engine would produce only water vapor, carbon dioxide and nitrogen as by-products; however, complete combustion is never achieved. As a mobile power plant, the diesel engine is relatively inefficient in terms of energy produced from the energy potential of the fuel. The diesel is not a perfect engine. The fuel burned can undergo a very large number of reactions in the combustion chamber. It only stands to reason that a large number of compounds are contained in the exhaust, actually, thousands of chemicals. The exhaust can be broadly divided into a gaseous phase and a particulate phase. Each phase is made up of organic and inorganic compounds. The vapor phase contains carbon monoxide, sulfur dioxide, various oxides of nitrogen and many hydrocarbons. The particulate phase contains clusters of respirable inorganic particles made mostly of carbon. This paper will address the health hazards, as we know them today, of the major components of the particulate phase in the exhaust of diesel engines. It will briefly examine the operational factors of the diesel engine as it applies to particulate emissions. Longitudinal studies of occupationally exposed miners are needed with documentation of levels of exposure before a chronic effect of exposure can be determined. At this time, it is not possible to conclude from human studies the level of diesel exhaust exposure that results in the observed lung cancer risk.

Jan 1, 2001

By M. Deal

Particle size analysis is a fundamental measurement utilized in the mining industry, especially in comminution, hydrometallurgy, and mineral processing. While sieves and cyclosizers are the standard methods used to determine particle size distributions, in recent years alternative instruments have been developed that claim to provide more rapid and equally reliable results. Newmont Metallurgical Services has implemented the use of two such instruments, along with traditional methods (sieves and a cyclosizer), on a daily basis. The Malvern Mastersizer 2000 laser analyzer is a wet sample system that can analyze particles in the size range 0.02µm to 2000µm, and the Horiba CAMSIZER® is a dry system that can analyze particles in the size range of 30µm to 30mm using digital image processing. A comparative analysis has been performed to determine the applicability of each particle sizing method in laboratory testing.

Jan 1, 2011

By S. C. Chelgani

The Thor lake deposit is a world class resource of rare earth (REE) metals and minerals in Canada. Development work to optimize a REE mineral recovery process flow sheet is underway, however, given the ore mineralogy; the developed reagent scheme is relatively complex. As part of a research project, micro flotation tests were conducted on a feed sample in order to examine factors affecting stream partitioning. SEM-EDX was performed to evaluate variability in grain composition between streams (concentrate and tails) and TOF-SIMS surface analysis was used to determine statistically significant differences in surface species particularly related to potential activation (or depression) of the examined mineral phases. SEM-EDX analysis reveal that the concentrate has a significantly higher proportion of REE bearing grains (carbonates and phosphates) relative to the tail (almost none were identified). Spectral fingerprinting by TOF-SIMS has allowed for the identification of all reagent species investigated. Reagent signal intensity discrimination on test stream mineral surfaces was observed by the TOF-SIMS analysis using reagents at plant concentration levels. TOF-SIMS analysis confirmed that REE bearing grains reporting to the concentrate are doing so in response to collector attachment whereas grains reporting to the tail are doing so in response to a lack of collector and/or in combination with the presence of the depressant. The surface analysis of gangue phases reveal a similar reagent discrimination; the signal intensity of collector species was significantly higher on the concentrate samples relative to the tails while depressant species were significantly enriched on the surface of the gangue phases in the tail samples. A detailed evaluation of the surface species representing the various reagents used in flotation scheme revealed a distinct competitive relationship between two of the reagents. The surface analysis identified that when used in concurrently, there appears to be a negative feedback resulting in a significant reduction in loading for several of the collectors on grains reporting to the concentrate. An evaluation of the effect of reagents on REE mineral in pilot plant is currently under way. Key words: Rare earth minerals, Flotation, Surface chemistry, TOF-SIMS, SEM-EDX

Feb 27, 2013

By Dan Preston, Shane Yanagisawa, Robert Marshall, Don Deere

Geotechnical Baseline Reports often estimate the number of cobbles that will be encountered in terms of volume or weight. These estimates are practically impossible to verify in the field. ClaroVia Holdings in conjunction with Frontier Kemper Constructors Inc. developed Digital Geologist 2.0 to classify and count cobbles discharged from an EPB TBM at the RSC7 project in Burbank, CA. The system worked by using two stereoscopic laser sensors with a global shutter to scan and count cobbles at 12 frames per second. Results of the effort are revealed along with lessons learned and paths for improvement.

Jun 13, 2023

Introduction The science of geometallurgy requires that ore characterization be performed holistically, that is, with consideration of ore quality on plant performance and product quality. Geometallurgy, by definition, requires knowledge of geology, mineralogy, extractive metallurgy and pyrometallurgy. Examples of the ore characterization challenges for the geometallurgist in the production of iron ore pellets from low-grade Proterozoic iron formation are presented here. Ore Characterization Ore characterization, the quantifying of mineralogy, grain size and the texture of ores, is an often overlooked tool in improving process efficiency. Some mineral related problems are not unique to the production of iron ore pellets; e.g. the problems caused by expanding clays in flotation. The negative impact of carbonate minerals in the ore on pellet productivity and pellet quality are unique. The long and complex geologic history of Precambrian iron formations contribute to modifications of grain size and the introduction of complex textures.

Jan 1, 2007

By R. D. Hagni, P. A. Shivdasan

Cathodoluminescence microscopy (CLM) is uniquely applicable to the study of carbonatite-related fluorspar ore deposits. The mineralogy of the carbonatites, sodic and potassic fenites, marbles, quartzites, and fluorite ores are readily determined and characterized. Calcite, dolomite, apatite, fluorite were deposited dominantly under high temperature conditions and they exhibit strong cathodoluminescence (CL). Three types of carbonatites have been recognized at the Okorusu, Namibia carbonatite complex and fluorspar mines by field mapping and laboratory CLM. The main carbonatite intrusion is fine grained and consists mainly of calcite. A later phase of pegmatitic carbonatite consists of calcite, magnetite, Fe-rich pyroxene, apatite, and pyrochlore. Pyroxene carbonatites were recognized mainly through their study by CLM.

Jan 1, 2001

By J. MacFadyen

The U.S. cement industry, including Puerto Rico, again set a record in terms of production and shipments. The increase in shipments came primarily from imports of portland cement as domestic production from produced and imported clinker gained only 1.9 Mt (2.1 million st). Clinker production as reported to the U.S. Geological Survey (USGS) was 88.6 Mt (97.6 million st), an increase of 1 percent. Gray and white portland cement production from domestic and imported clinker, estimated at 93.5 Mt (103 million st), was up 1.9 Mt (2.1 million st). Masonry cement shipments of 5.5 Mt (6 million st), which equates closely to production, was up 6.3 percent. Blended ce-ment shipments were up 35.9 percent from 2004 at 2.35 Mt (2.6 million st).

Jan 1, 2006

By T. W. Beck

Drilling into coal mine roof strata to install roof bolts has the potential to release substantial quantities of respirable dust. Due to the proximity of drill holes to the breathing zone of roof bolting personnel, dusts escaping the holes and avoiding capture by the dust collection system pose a potential respiratory health risk. Controls are available to complement the typical dry vacuum collection system and minimize harmful exposures during the initial phase of drilling. This paper examines the use of a bit sleeve in combination with a dust hog-type bit to improve dust extraction during the critical initial phase of drilling. A twisted-body drill bit is also evaluated to determine the quantity of dust liberated by comparison to the dust hog-type bit. Based on these laboratory tests, the bit sleeve may reduce dust emissions by one-half during the initial phase of drilling before the drill bit is fully enclosed by the drill hole. Because collaring is responsible for the largest dust liberations, overall dust emissions can also be substantially reduced. The use of a twisted-body bit has minimal improvement on dust capture compared to the commonly used dust hog-type bit.

Feb 27, 2013

By D. J. Kunz

Myanmar Ivanhoe Copper Company Ltd. (MICCL) has been operating the Sabetaung- Kyisintaung (S&K) Project producing LME Grade A Copper Cathode using the Heap Leach-SX-EW Process since 1998. The mineralization is mainly Chalcocite and the mine has a life of 20 years at the designed annual production of 25,000 tonnes of cathode copper. Design capacity was achieved within two of months of start-up. The mine is among the world’s lowest cost, Heap Leach-SX-EW operations. Information regarding plant design and operation are presented along with the challenges lying ahead and the latest developments. Daniel Kunz is President and Chief Operating Officer of Ivanhoe Mines, and a director of MICCL. He has more than 20 years’ experience in mining, construction and engineering. Prior to joining Ivanhoe Mines in 1996, Mr. Kunz was Vice President and Controller of Morrison Knudsen Corporation, a major international mining and construction company. He was also President and Chief Executive Officer of MK Gold Company, a public mining company listed on NASDAQ.

Jan 1, 2001

By A. Jennings

[ ] In November 2005, Essroc Cement, part of the Italcementi Group, commissioned a long overland conveyor at their Nazareth plant in Pennsylvania. This conveyor, tagged CV-105, was designed to transport 1000 tph of limestone from the quarry to the kiln, and 400 tph of hot clinker (at 300°F) at back from the kiln to a handling facility about halfway back. Conveyor CV-105 is 8969 ft (2733 m) long. It gains 152 ft (46 m) of elevation in the first 1570 ft (480 m), then is mostly flat for the remaining 7400 ft (2250 m) (Figure 1). After the limestone is discharged at the head pulley, hot clinker is loaded onto the return side of the belt. This clinker can be discharged at one of two locations.

Jan 1, 2012