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By Veliko Kertikov

Complicated processes of heat exchange and evaporation, leading to changes in the temperature and humidity of the ventilating air flow, take place during the driving of headings. In the case when virgin rock temperature is high, the increase in air temperature and humidity is significant. This causes a deterioration of climatic conditions in the headings. Procedures for predicting the changes in air temperature and humidity are discussed, together with appropriate calculations and computer programmes. Predicted results for example scenarios are used as a background for the selection of approaches and means to improve the climatic conditions in a dead-end heading using auxiliary ventilation.

Jan 1, 1997

By S. Upadhyay, A. M. Afrapoli

"Fluctuation in market price of mineral products has enforced mining companies to cut down their operating costs. One useful way of reducing operating costs in mining operations is to make optimal operational decisions, incorporating efficient mining fleet management systems (FMS). Over the last 50 years, several types of FMS have been developed and introduced in the mining systems around the world. However, there are two major shortcomings in existing systems. Firstly, none of the existing systems consider effects of the short-term plan on dynamic truck assignment. Secondly, most of the existing FMSs make decisions in a way that optimize a specific objective while ignoring others. Herein, we propose a multi stage and multi objective FMS that deals with aforementioned shortcomings of the currently available systems. The developed FMS, in its upper stage, links semi-dynamic operational decision making process to the short-term production plan by simultaneously assigning shovels to mining faces and allocating trucks to the shovels by implementing its first multi objective decision making model. Then in its second stage, in a real time dynamic decision making process, it assigns trucks to shovels and corresponding destinations by optimizing its second multi objective decision making model. The developed fleet management system has been verified using an Iron ore case study and the results are presented in this paper. INTRODUCTION Open pit mining method is the most common method to mine mineral from the earth. Based on Wetherelt and van der Wielen (2011) there exist 2500 open pit metal mines that are categorized as industrial scale mines. Over all of those, the amount of material handled using truck and shovel material handling system is more than the amount handled by all other systems together (Humphrey & Wagner, 2011).It has been proven by several studies that more than 50 percent of operating cost in a truck and shovel based open pit mining operation is accounted for material handling (Moradi Afrapoli & Askari-Nasab, 2017, Alarie & Gamache, 2002, Ahangaran et al., 2012). Thus, introducing even 1 to 2 percent cut in its material handling cost saves huge amount of money for the stakeholders. Over the last 50 years, two major areas have been identified to cut this cost. On one hand mining industries have been implementing equipment with higher production capacities, and on the other hand, researchers have been developing operations research techniques to make dynamic decisions as close to optimal as possible to deduct operational costs in truck and shovel based mining operations."

Jan 1, 2018

Brace yourself-what used to be a 1 billion ton deposit is now a 1 Gt deposit. And that 1520-hp ball mill is now a 1.134-MW ball mill. Beginning with this issue, all engineering units and statistics in MINING ENGINEERING will be reported in SI units. The exception to this is the Technical Papers section, where units may still be reported by dual notation. For the past four years, ME has reported all units of measurement first in SI, followed in parentheses by the equivalent English value. This metrication policy, adopted by the SME-AIME Board of Directors in September 1975, was designed to aid magazine readers through a transitional period from English unit reporting to SI unit reporting. In October 1979, the SME-AIME Publications Board completed the English-to-SI transition by requesting the editorial staff, beginning February 1980, to report exclusively in SI. The Publications Board also requested the editors to prepare a chart of SI conversions useful to ME readers; this information follows on pages 156-157. The What and Wherefore of SI In 1960 the General Conference on Weights and Measures met in Sevres, France, and recommended that a new metric system-one that could uniformly cross all international borders-be adopted to replace all other metric systems. The outcome of this recommendation was the SI system of units, an abbreviation for le Systeme International d'Unites (the International System of Units). It replaces the more familiar cgs (centimeter-gram-second) system and the m/ksA (meter-kilogram-second-Ampere) system. SI consists of seven base units, two supplementary units, and a number of derived units. Other units, called allowable units, may be used even though they are not part of SI. The seven base units are: meter (length); second (time); kilogram (mass); mole (amount of substance); kelvin (temperature); ampere (electric current); and candela (luminous intensity). The two supplementary units are radian, a measurement of plane angle, and steradian, a measurement of solid angle. Supplementary units can be used in combination with SI units, e.g., radiant intensity is expressed in W/sr, watts per steradian. Derived units are combinations of base and supplementary units. Velocity is expressed as meters per second (m/s), and acceleration as m/s'. Using the relation established by Newton's second law of motion, force is expressed as kg-m/s2, more commonly known as the newton (N). Energy (work) is force times distance, expressed as kg-m/s2 and known as the joule (J). Power is work per unit time, expressed as kg, m2/s3 and known as the watt (W). Allowable units are the exception to the rule-they are not taken from base or supplementary units but, nevertheless, are used in the SI system. Volume units are normally expressed as the cubic measure of a length, such as cm 3. But a fluid volume of a cubic decimeter (dm3) is called a liter (L); the "L" is capitalized in another special SI rule to keep the lowercase "1" from being confused with a numeric "1". Other allowable units are degrees Celsius (°C) for temperature; and the minute (min), hour (h), day (d), and year (a) for time measurements. The prefixes in the table on the following page are used with SI units to express the magnitude of a measured quantity. A mill that processes 1000 tons of ore per day would be designated a 1 kt/d mill; a mine producing 10 million tons of ore per year would be called a 10 Mt/a mine. The rule here is to use prefixes that keep the value in a convenient range from 0.1 to 1000. In other words, it would be incorrect to write 25 000 kg-the prefix should be changed to indicate 25 Mt. One of the distinct advantages of SI is that it retains the decimal relation between multiples and submultiples of the base units for each physical quantity except for time. One more rule of SI syntax-numbers are separated into groups of three with a space between each group rather than a comma, e.g., 3,839,174 becomes 3 839 174. By the same token, a decimal number is also broken by spaces, e.g. 0.738153 is written as 0.738 153.

Jan 2, 1980

By J. A. Ryder

Compressed air is a relatively inefficient yet very convenient vehicle for transmitting mechanical energy. It is inefficient when compared to, say, hydraulic or electric energy systems since compressor and pneumatic machine efficiencies are quite low (in the range 20-65%) and reticulation losses can be quite high unless adequate pipe diameters are used to minimize friction drops. It is convenient in that capital and maintenance costs of pipes and machines are exceptionally low, the equipment is flexible and lightweight, the technological level is simple, the form of the energy supply is intrinsic- ally safe, and as an additional minor but psychologically important benefit, it provides a ready source of cooling and air supply for emergency use in deep hot mines. It is for these reasons that compressed air is a premier source of energy for many forms of underground equipment, in particular hand or rig-mounted rockdrills, some forms of rock- handling equipment, and a host of minor applications including agitators, small-lift pumps and temporary f am installations. In a typical S. African deep-level gold or platinum mine, compressed air generation accounts for 15% of the total mine electrical energy bill - more than is used for hoisting. In these mines it is not uncommon for over 100 km of underground compressed air piping to be installed, primarily to supply handheld rockdrills.

Jan 1, 1979

Stratabound uranium deposits consist generally of two comingled geologic and statistical populations. Barren zones, usually having radiometric assays too low for recording on digitized logs, comprise a large portion of a mineralized stratum. In between are mineralized zones; where the grades are distributed essentially lognormally. Estimation of open-pit ore reserves requires the prediction of the tonnages of selective mining units (the smallest mined volume which may be segregated as ore or waste) and their grades within panels of convenient size for open pit planning and economic analysis. The proportionate tonnage of mineralized selective mining units within each panel can be predicted by kriging an an indicator function assigned to each composite (1 if mineralized, 0 if barren). Next, using logarithms of mineralized assays, the conditional lognormal distribution of grades of mineralized selective mining units can be found. Using this distribution and the krigedestimate of the probability a selective mining unit is mineralized, the grade and tonnage of selective- mining units above any cutoff can be predicted. A case study illustrating this two- step procedure is presented for the Imouraren uranium deposit located in the Republic of Niger. Using cross validation, the estimation procedures were checked and were shown to be adequately accurate for mine planning purposes.

Jan 1, 1979

By Fred N. Kissell, Robert J. Timko

Safe escape from coal mine fires continues to be a concern of the mining industry. The most life-threatening fires occur outby the working sections. Because stoppings always leak some air, an outby fire may in time cause intake escapeways to become contaminated with smoke and toxic gases. Smoke and gas infiltration into intake escapeways can be minimized by raising their air pressure over that of adjacent airways. This can be done by checking off the intake escapeway near the working face. The Bureau of Mines has investigated the use of a parachute stopping as a quick-erect check curtain during mine fires, and the concept has been tested in several mines. In every instance, when a parachute stopping was erected on the section, the intake pressure went up substantially. The pressure-raising effect of the parachute persisted for up to 1200 m (4000 ft) outby. Results indicate that checking off the intake escapeway may serve as a viable way to improve safety during mine fires.

Jan 1, 1991

By Robert D. Brown, Charles A. Sorrell

The decade of the 1980's saw "advanced materials" become a key factor among the industrialized nations, with the United States, Japan, and the European Economic Community being the major competitors. All three have identified communications technology, advanced materials, and biotechnology as the keys to future industrial leadership and the closing decade of the 20th Century is expected to be an era of rapid development and restructuring. The progress of EC'92, the effort to develop uniform standards and remove trade barriers in Europe; the determination of Japan to commercialize advanced structural ceramics, alloys, composites, and superconductors; and the emergence of less developed countries as major supplies of commodity materials pose enormous challenges to the position of the United States as an industrial and financial leader. A consensus is developing that the industries that are first to commercialize the large array of new structural materials and electronic, optical, and magnetic materials and devices will be those who determine the structure of national and world economics. Many technical, economic, legal, political, social, and cultural factors are important determinants in the race to commercialize new materials. Millions of words have been written about these factors and their interdependence; yet the sheer complexity of the problems, the rate at which changes are taking place, and the economic risks involved are so great that government policy makers and industrial decision makers find adequate understanding to be very difficult. Of the many factors involved in advanced materials, the Bureau of Mines has the statutory responsibility to provide information on where materials can be found and how they are mined, extracted, purified, combined, and recycled. It is obvious that minerals availability is essential to implementation of any new technology just as there can be no commodity metals industry if the ores are not available. Because "minerals availability" for commercialization of advanced materials and devices is more complex than for commodity materials and a new mix of materials and processes is emerging, the Information and Analysis Directorate of the Bureau of Mines is redirecting resources to provide reliable information for policy and decision making. The Office of Advanced Materials Coordination (OAMC) was established as a staff operation in July 1987 to assist the efforts of the divisions and branches. The key issues and problems were defined and the role of the Bureau was outlined (Sorrell, 1987, 1988). In February 1990, the functions of OAMC were transferred to the new Branch of Advanced Materials, a line organization parallel with the Branches of Ferrous, Nonferrous, and Industrial Minerals, and was given the responsibility for developing new methods to acquire, analyze, and disseminate information about new materials. The purpose of this paper is to provide definitions, a summary of major issues and problems, an overview of minerals and processing availability problems, and a perspective of the ways in which the mining and materials industries can help to ensure domestic availability of raw and processed materials.

Jan 1, 1990

By Qinghua Song, Jianhong Chen, Shan Yang, Zhiyong Zhou

"The development process of Metal Resources Technical and Economic Evaluation Expert System (MRTEEES) is introduced in the aspects of requirements analysis, design of the expert system, main functions of the expert system and features of the expert system. The system is based on C/B/S mixed mode and uses ASP.NET technology with .Net Framework being chosen as the development platform and metal resources database providing data support at the bottom layer. The system is an auxiliary management system for metal resources technical and economic evaluation and has the basic functions of auxiliary decision analysis, metal resources database management, data management and comprehensive query. Technical and economic evaluation model can be set up by users independently according to at which stage a project is, mainly including exploration stage, development stage and production stage, and according to the mining methods, for example underground mining, surface mining and in-situ leaching mining. Then, the technical and economic evaluation parameters can be generated. By inputting the value of each parameter in a simple and convenient way, the evaluation results can be directly calculated out and shown in the form of diagrams among others, and feasibility evaluation report can also be automatically generated, making the technical and economic evaluation process accurate and efficient. As the system can achieve the functions of scenario analysis, sensitivity analysis, shareholder’s returns analysis, horizontal comparison of different projects, it can improve the ability of project senior decision makers for rapid response to the rival and meet the demand of pricing negotiations. IntroductionWith the arrival of a new round of industrialization upsurge in both developing and developed countries, growth of demand for metal resources is entering a new stage. Population involved in the new industrialized countries is about four times that of all previous industrialized countries, implying resource consumption increases dramatically both in speed and in quantity. It is a must to seize the strategic opportunity of developing and utilizing metal resources around the world to lay abundant resource base for national industrialization. Objectively speaking, global configuration of metal resources is an inevitable tend. Presently, many issues, for example, resources exploration, mining, merge of mining companies, metal trades, mining financing, etc., generally show the feature of globalization. For the reality that competition for metal resources is becoming fiercer, industry standards of mineral resources will undoubtedly be improved. Occupying large scale mineral resources with high grade and developing them with low cost is the base for the survival of mining companies and metal resources merchants. With the growing demand of global investment in mineral resources exploration, which is at the upstream of the industry chain, geological exploration industry is promising. Globally building market relationships for mineral resources exploration companies is key to their sustainable development. Developing large and super-large deposit with low cost is also an important approach to enhancing core competence of a country or an enterprise. Mining companies around the world are rushing to purchase mineral resources globally. However, in different countries, economic, financial and tax systems for mineral resources vary greatly, and mining and processing techniques, technical parameters and equipment selection also change a lot. Thus, pro-phase research work is necessary for feasibility evaluation of mineral resources projects and it can be time wasting if taken in the traditional way. It is necessary to accelerate the process considering the complex and rapidly changing international situation."

Jan 1, 2017

By J. Alvarez, S. Helle, U. Kelm, M. Pincheira

The principal geological and mineralogical characteristics of Chilean porphyry copper deposits are described. Elevated contents of fine grained ore and gangue material may cause copper losses and pose problems or render useless the flotation process. Examples of chalcopyrite and bornite size distributions are given. The state of the art of mineralogical and mineral chemical characterization in Chile is evaluated permitting analyses to lm and nm level by lacking the regular use of direct surface analysis.

Jan 1, 1998

By J. R. Palmes

Flocculation of coal fines with varying degrees of wettability was studied under well defined hydrodynamic conditions. In this study, three coal samples were tested with three different flocculant types. The results revealed that flocculation depends strongly on both the coal surface properties and the type of flocculant used. A hydrophobic flocculant was found to be effective for hydrophobic and slightly oxidized coal, a semihydrophobic flocculant was found to flocculate, to different extents, all of the samples except the oxidized cool, and polyacrylimide flocculated all of the coals, which is a clear indication of its insensitivity towards coal wettability.

Jan 1, 1994

By B. W. Cavender

Innovative mining and metallurgical operating techniques and processes can be identified and developed by analyzing changes as they occurs within the mine, plant, technology or industry. Sources of change to be monitored for innovative opportunities include unexpected successes or failures, incongruities between perceived and actual events, process needs, changes in perceptions and the development of new knowledge. Innovation can be organized, practiced and managed. The perception of change as an opportunity rather than a threat is mandatory, as is the systematic measurement of innovative performance. Innovation is enhanced by specifically designed policies regarding organizational structure and staffing, daily management practices and compensation and incentives.

Jan 1, 1996

By D. R. Kalasky, J. M. Mutmansky, B. Kolonja

This paper considers simulation of truck dispatching systems using maximum expected production of the truck-shovel system as the measure of performance. Two analysis methods are utilized: multiple comparisons with the best (MCB) and the combination of MCB with the variance reduction technique known as common random numbers (CRN). These two techniques are compared via simulation experiments. Results show that the combined procedure of MCB with CRN is the superior tool to use to reduce the total number of replications needed to ensure the specified probability of correct selection from a number of systems. In this case study, MCB with CRN reduced the variance by 29% and the number of required replications by 48%. Also, the MCB with CRN procedure narrowed the confidence interval by 18%.

Jan 1, 1995

By Normand Tassé

Reactive barriers, which consume oxygen, are prospective though unconventional alternatives to physical barriers for Acid Mine Drainage prevention. However, a reactive barrier implies a problem of duration. Pore gases were analysed in several wood waste piles in order to understand the factors which control wood degradation and help to determine the effective life span of such a cover. Long term efficiency seems to strongly depend on the degree of water saturation at the bottom of the pile, likely because the development of a microbial biomass in such an environment helps to keep the amounts of nutriments and readily metabolizable organic substrates at a high level, which in turn promotes oxygen consumption.

Jan 1, 2000

By Numan Elmas

Barite deposits located in Dinek and surrounding region have important economic features with their large reserve capacity for Turkey. The objective of this study is to elucidate geological and depositional characteristics in terms of. site investigation and chemical analysis. In order to do this, geological area of about 300 km2 was examined and detailed geological map was constructed. It was observed that Barite mineralization in these deposits was occurred in carbonate and pelitic rocks of Lower Cambrian-Lower Ordovician. Deposits were exposed to advanced diagenesis regional metamorphism and tectonics that rotated and deformed the barites; therefore, barites shows secondary veins, brecciate and fracturing structure. Even though, a few light isotope values of barites may suggest hydrothermal and exhalative sedimentary characteristics or possible mixing with magmatic fluids, generally heavy isotope values indicate that the sulfate ions were supplied from coeval seawater and, many of sedimentary features and petrological, geochemical characters support dominantly sedimentary origin.

Jan 1, 2005

By Ulf Marklund, Stig Markstrom

Pioneering work with pilot scale autogenous grinding started in Boliden 1956. From 1961 to 1991 eleven fully autogenous grinding (AG) circuits have been installed at various concentrators within the Boliden company. A compact two-stage grinding system was de- signed in the beginning of 1970s. The system included a pebble extractor which feed the secondary grinding stage with grinding media. The APC grinding system (Autogenous/Pebble/Crusher) is a further development of the AG concept. A new design of the Boliden pebble extractor together with improved control strategy make the performance of the APC system suitable to almost any ore quality. The Boliden AG concept is probably the most cost efficient grinding system of today.

Jan 1, 1998

By C. A. Rowland

Comminution efficiency can be expressed in three different ways. Theoretical Efficiency: actual energy consumed, in a comminution machine compared to the theoretical energy required to make the size reduction. Operating Efficiency: compares the operating work index, calculated from production comminution machinery operating data, to the Bond Work Index from bench scale comminution tests or calculated from pilot plant operating data. Economic Efficiency: income compared to planned income. Using the Bond Work Index and operating work index, this paper explains how to determine operating efficiency.

Jan 1, 1998

By Paul G. Schmidt

Exxon Minerals Co. was exploring for mineral deposits in Precambrian terranes of the US portion of the Lake Superior region in the late 1960s. Exploration drilling and other activities had been concentrated on massive sulfide prospects in northeastern Minnesota, but general exploration studies and competitor scouting were conducted in other areas of the region. These activities drew attention to Wisconsin in 1969 when it became apparent that Bear Creek Mining Co. had made a discovery near Ladysmith in the northwestern part of the state. Observation of their drill hole pattern suggested that a massive sulfide deposit, since named the Flambeau deposit (Schwenk, 1977), had been found. With this background, Exxon initiated an exploration program for Precambrian massive sulfide deposits in northern Wisconsin in 1970 (Figs. 1 and 2). Northern Wisconsin is extensively mantled by Pleistocene glacial drift and bedrock outcrop is sparse. Other than iron mines in the extensive iron formations along the Wisconsin-Michigan border and Jackson County, no significant mineral deposits were known in the Wisconsin portion of the Precambrian Shield until the discovery of the Flambeau deposit. Until the mid-1970s, the only specific published literature on the Wisconsin Precambrian consisted of old outcrop locations and descriptions in journals of the Wisconsin Geological and Natural History Survey (Chamberlain, 1882; [ ] Weidman, 1907; Hotchkiss, 1915) and the summary maps of Dutton and Bradley (1970).

Jan 1, 1991

By P. K. Mululi, T. M. Yegulalp

The number and type of trucks and shovels used are two important factors in determining the optimal design parameters of an open-pit mining system. The characteristics of the arrival and service-time distributions of the trucks determine the performance measures of a truck-shovel system when it is modeled as a closed queuing network. In all of the previous analytical queuing studies of truck-shovel systems, trucks are assumed to be identical with respect to their arrival and service-time distributions. This assumption, although desirable for reducing computational difficulties, causes either underestimation or overestimation of the performance measures, depending on the number and types of equipment used in the model. The relative error in performance measures could be significant when the number of different types of trucks and shovels is large. In this paper, an analytical method is proposed to model the truck-shovel system as a multiple-class closed queuing network. This approach provides the capability of estimating system performance measures for planning purposes when the truck fleet is not necessarily composed of identical trucks. An example of truck-shovel systems is presented to show how the incorporation of different types of trucks affects performance measures.

Jan 1, 1998

Exploration for SX-EW copper deposits and plant operation depend largely on the copper and gangue mineralogy inasmuch as? they govern the feasibility of leaching. Mineralogical parameters are pivotal in identifying if an ore is suitable to dump, heap, thin layer, vat or agitated leaching and/or if the ore requires curing, bioleaching or alternate lixiviants. Problems in metallurgical testing, production leaching and recovery forecasting are very often related to lack of mineralogical data. This presentation will illustrate the use of quantitative mineralogical analysis for exploration, acquisition assessment and optimization of copper leach operations.

Jan 1, 1996

By C. A. Pickles, D. Mallette

Silicon nitride (Si3N4 ) is an advanced structural ceramic materia1 which is presently being considered for a number of potential engineering applications, particularly in heat engines, gas turbines, and electronics. With respect to other structural ceramics, silicon nitride has relatively low thermal conductivity and thermal expansion coefficients and a moderate elastic modulus. Thus, during thermal cycling the stresses developed in this material are lower than in other structural ceramics. At the present time silicon nitride is produced via three main processes: thermal decomposition of silicon imide or amide, treatment of silicon tetrachloride or silane vapour with ammonia and nitriding of silicon powder. These three methods of production are discussed with particular attention to the effect of morphology and phase content on the properties of the final product. In this work carbothermal production of silicon nitride has been studied in a high temperature resistance furnace. Compacted briquettes of silica and carbon were produced which were reacted in a nitrogen atmosphere. The optimum reaction temperature and the carbon to silica ratio were found to be 1425OC and ten to one, respectively. The presence of large amounts of ash in the reductant promoted the formation of silicon nitride. The specific surface area of the briquettes did not have a large effect over the range studied in the present work. Briquette seeding with small amounts of Si3N4 was effective in increasing the reaction rates.

Jan 1, 1990