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By George Filz, Peter R. Cali

"Unnecessarily restrictive specifications could be limiting the cost effectiveness of deep mixing (DM) applications and therefore limiting use of DM on projects where there are other options. Excessively restrictive standards demanded for strength and permeability certainly increase contractors’ bid prices, and costing the owners and, in the case of Government projects, the taxpayers more than necessary. Yet, lax or ineffective specifications often exist for some vital components of the quality assurance and quality control. In this paper, specifications for key elements of DM design and construction are examined. Recommendations are made to improve and streamline DM specifications to better serve the common objective of constructing a safe and cost effective ground improvement project.INTRODUCTIONSpecifications should, at their best, convey the project design requirements and provide clear direction to the contractor regarding requirements for submittals, materials, execution, measurement, schedule, and other aspects as necessary. The specifications should not be overly conservative, restrictive or ambiguous, and they absolutely should not be deficient in measurement of quality. Guide specifications or recycled sections from previous projects often form the template for new project specifications. But standards that appear in guide specifications or from former successful construction should be critically scrutinized by the designer for relevance before using the copy/paste functions of the specifications writer’s keyboard. Because work does not always go as smoothly as planned, specifications for remediation of non-compliant construction should be clearly stated and enforced. Often, non-compliancy is reviewed after-the-fact and deemed to have met the design intent, indicating that either the specifications were too restrictive or the enforcement too weak.The Federal Highway Administration Design Manual: Deep Mixing for Embankment and Foundation Support, October 2013, was written by a panel of DM expert design practitioners and contractors. Guide specifications are included as Appendix C of the FHWA manual. Those guide specifications have been updated in the deep mixing section of the www.GeoTechTools.org website, and the updated specifications represent the most complete and authoritative compilation published to date. Although the specifications for DM at www.GeoTechTools.org are current and complete, and they portray the state-ofthe- practice, they too must be modified to fit specific DM applications, project needs, and site conditions. The keys to a good set of specifications are to prescribe construction only to the level that is required to meet the design intent, to require appropriate quality control and quality assurance (QC/ QA) activities, and to clearly address remedial measures required for non-compliant work."

Jan 1, 2015

By A Scott, I Onederra

A great deal of technical and research effort has been applied to the development of models to predict fragmentation from rock blasting. A number of quite useful empirical or engineering models are currently available to blasting engineers and consultants, while more sophisticated approaches using mechanistic and numerical descriptions of rock breakage continue to be developed and applied by researchers and explosives companies.The fragmentation resulting from any blast will be heavily dependent on the properties of the rock mass being blasted; however, most empirical models rely on ‘rock factors’ generated from simple rock mass properties to describe the influence of the rock on the blasting outcome. In contrast, mechanistic models need explicit rock mass properties that require sophisticated laboratory measurements and detailed structural data if realistic outcomes are to be generated. The fragmentation modeller is caught between excessively simple rock mass descriptions for the empirical models and excessively complex data requirements for the mechanistic models.This paper briefly reviews the basis of a range of fragmentation models and the rock mass properties on which they rely. Shortcomings in the way that the mining industry tends to characterise the blasting properties of rock are discussed and some practical approaches are described to quantify these properties in both operating and greenfield mining environments. Case studies are presented where specific additional breakage properties and modelling features have been needed to generate a useful description of the fragmentation achieved.CITATION:Scott, A and Onederra, I, 2015. Characterising rock mass properties for fragmentation modelling, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 149–160 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By Timothy R. Eby

"The Wabush Mines project was formed in 1956 to develop a large iron ore property in Western Labrador. The town of Wabush along with the mining and concentrating facilities are located 640 air miles from Montreal, and 734 air miles from St. John's. The operation has been in production since late 1964.While mining and concentrating operations are located in Labrador, the pelletizing facilities are situated 275 miles south at Sept-Iles, Quebec. Dedicated in 1965, Wabush produces six million tons of high quality iron ore pellets annually. The company employs 1, 550 people at Wabush and the Pointe Noire plant at Sept-Iles.Wabush Mines is an unincorporated joint venture of three companies -The Steel Company of Canada, Dominion Foundries and Steel Ltd. and the remaining 58% by the Wabush Iron Co. Ltd. Wabush Iron Co. Ltd. is in turn owned by six companies: The Youngstown Sheet & Tube Company, Inland Steel Company, Interlake Inc., Wheeling Pittsburg Steel Company, Finsider International S.A. and Pickands Mather & Company which is also managing agent.The town of Wabush is set in a remote part of Northern Canada accessible only by rail and air transportation. But this in no way has hindered the growth and development of the area. Modern housing units, shopping facilities, airport and of course, recreational facilities are all patt of every day living amenities, an accepted aprt of southern communities, but quite unique for northern isolated mining localities."

Jan 1, 1978

By W. C. Morgan

The Federal Surface Mining Law enacted in 1978 is now being translated into regulations which must be followed in future coal mining. Substantial change to mining procedures is required to maintain stricter air and water control while mining and to return the mined out land to equal or better use than before. These changes do not come easy; and in most cases, they create a substantial additional cost. Based on field observations and mining studies, Caterpillar has been making suggestions on the use of their types of equipment to conform to the new standards at the least cost. This paper will be a brief review of some of the overburden stripping and reclamation methods suggested by Caterpillar. A production and cost comparison of dragline, scraper/dozer and truck, loader systems in 20 to 150 ft. Overburden conditions illustrates potential cost savings using mobile equipment.

Jan 1, 1980

By H. Sevim

Three transportation and handling alternatives for delivering dry coal combustion residues from power plants to underground coal mines were evaluated technically and economically. The objective was to transport, handle, and inject the residues into the old workings of the mine at a minimum cost. This objective was accomplished in two steps: I) Simulation models were developed and utilized in identifying technically feasible designs in each alternative, 2) Technically feasible designs were economically evaluated to obtain the cost-per-ton of material transported. The designs that provided the minimum cost-per-ton were declared optimal An analysis was conducted for varying distances and tonnages to reveal favorable operating ranges of each alternative.

Jan 1, 1996

By Herschel H. Potter

While preparing this paper, I soon realized I had a problem in defining what injuries should be classified as "personal." Admittedly, in some cases, falls of persons, sprains and strains, pulling and pushing injuries, and back injuries may have been caused by the individual. But, I believe the number of injuries directly attributed to an individual's carelessness is relatively small in comparison to the total number of injuries in those categories. For discussion purposes, the injuries most often considered to be personal, that is, caused by individuals are those classified as back injuries. My paper will be devoted to back injuries because this category represents the greatest number of injuries occurring in coal mining. A man's best friends are his wife, his back, and his dog. The back, however, has a reputation of not being as faithful as his other two friends.1 "Industrial back injury is one of the major occupational health problems plaguing industry to- day. According to national surveys, back injury accounts for more lost time than any other occupational injury and costs companies thousands of dollars in compensation, medical fees and over- time pay."2 A study conducted by USA Today found that back ailments afflict an estimated 75 million Americans, have totally disabled about 2.5 million adults, lead to as many as 200,000 required surgeries each year, are a leading cause of absenteeism and disability, are the second leading cause of hospitalization, are responsible for 18 million doctor visits a year and cost about 93 million work-days annually. The cost to industry is estimated at $14 billion a year.3 During the past 30 years, a great deal of accident prevention education has been directed toward the reduction of back injuries. However, this effort has not produced any great change in the incidence of the injury. Back injuries should be of the utmost concern to everyone here today. I don't need to tell you what the incidence rate is for back injuries, nor will I use any statistics to inform you of the incidence rate for the coal mine industry or any specific mine. It is only important to know that the number of back injuries is excessive. Back in- juries resulting from lifting have been and continue to be one of the most constant and undiminishing problems in the occupational environment. The fact is, we use our backs to per- form work that the back was not designed to do. Historically, manual materials handling related accidents have consistently accounted for the largest percentage of all industrial accidents. In fact, over 25 percent of all industrial accidents are related to handling of materials.4 In underground coal mining operations, material handling accidents account for even larger percentage of lost time injuries. In 1983, for example, they accounted for 34 percent of all lost time injuries and 32.6 percent of all non-lost time injuries. 5 I want to use one example of a task that will illustrate what I have just said: the building of a concrete block stopping. Each solid concrete block will weigh from 60 to 70 pounds. To build a stop- ping 6 feet high and 20 feet wide will take approximately 80 blocks. On the average, these 80 blocks will be handled at least four times from loading into the conveyance for transportation to being placed while constructing the stopping. This generally requires repetitive lifting from ground level. The next three slides demonstrate the lifts

Jan 1, 1986

By AIME AIME

THANKS to the excellent preliminary work of: the Division officers and the local committee the fall meeting of the Coal Division at Bluefields was a brilliant success. West Virginia was at its best with its beautiful mountains, good roads and foliage, just beginning to turn to autumn colors. The meeting began on time and was kept on time throughout. The papers were-well prepared and, being on subjects of live interest, provoked 'lively discussion. One factor in bringing this about was that they were not too numerous and that with one exception copies had been submitted in advance a sufficient time to permit of them having been studied. The Friday morning session was presided over by John .J. Lincoln of the Crozier Coal and Coke Co. and president of the Pocahontas Coal Operators Association. After brief announcements by Thomas H. Clagett, chairman of the local committee, regarding plans for the two day's involved, and by Howard N. Eavenson, chairman of the Division, the reading of papers was taken up.

Jan 1, 1931

There are presently in use many grinding mill control schemes and concepts. This paper presents one operating method of controlling the particle size of the cyclone overflows for proper metallurgical results and controlling the level of the cyclone feed sump and new feed rate to obtain lowest unit cost of finished (ground) material which is usually at the maximum grinding mill throughput. This system stresses simplicity of field instrumentation and control strategy. Both of these factors lead to better operator understanding and acceptance. The low capital investment of this system also makes it more attractive at the Buick Concentrator when compared to other more complicated systems utilizing mass flow measurement and a computer to calculate circulating load and infer particle size. Furthermore, it has the advantage of utilizing an actual measurement for control, rather than a difficult-to-maintain inferred value. There are several reasons for maximizing mill throughput at Buick. The milling rate before automatic control was too low when compared to mill throughput increases planned for the future. Through this new operating system, it appears Buick will not have to make major changes of mill motors and speeds to meet the increased? production rate. Also, since power costs continue to escalate, it is desirable to maximize the throughput to the grinding circuit and reduce overgrinding to achieve a reduction in power cost per ton of ore milled. Presently, 45% of the concentrators' total power is consumed in this grinding circuit.

Jan 1, 1977

By Edwin S. Smith

One of the many responsibilities of mining engineers and mill superintendents is to provide for the safe and economic disposal of wastes (or tailings) remaining after a mineral has been extracted from an ore. The cost of disposal of these tailings exerts a considerable influence on the minimum grade of ore extracted from the mine. It varies to a great extent with each project and is dependent on many diverse factors, such as the local topographical, meteorolgical, geological and seismological conditions together with the applicable water pollution laws of the area. The process used to extract a mineral from an ore determines the physical characteristics of the tailings and thus is one of the more important factors to be considered when planning disposal facilities. Today's trends .in ore-processing operations complicate the problems of waste disposal: recently developed extraction methods result in the production of finer tailings, the use of lower grade ores produces greater volumes of wastes, while the enhanced land values in the vicinity of industrial plants preclude the former practice of spreading wastes laterally and force the expansion of waste desposits upwards to greater heights. The frequent occurrence of stability problems in waste deposits indicates that many mining organizations may not be employing current soil mechanics concepts and practices. One of the most spectacular, and often most disastrous, types of tailings dike failure is that resulting from liquefaction of the fine particles combined with a breach of the main retaining dike.

Jan 1, 1967

By L. E. Porter

The demand for crude oil on the Pacific Coast during the year 1945. was so acute that the California crude supply had to be augmented by tank-car imports from the Texas and Rocky Mountain fields. Crude imports reached a high of 64,800 bbl. per day during June, with a total of 14,259,000 bbl. imported during the first 11 .months. The U. S. Navy also implemented the crude output from California pools by drilling and completing approximately 300 wells in the Naval Petroleum Reserve No. 1 (Elk Hills), from which an established production of 65,000. bbl. per day was reached in late February and maintained until Aug. 17, 1945, when it was reduced to its preprogram level of 15,000 bbl. per day. Even with the conclusion of the Pacific war on V-J day (Aug. 14), the military petroleum product requirements have permitted little material reduction in output of California crude to prewar rates. During the year, a total of 327-760,000 bbl. of crude was produced, or 19 per cent of the total crude production within the United States during the same period, as compared with 310,996,000 bbl. or 18.4 per cent of the nation's crude production in 1944.

Jan 1, 1946

By R. W. Van Dolah

An attempt has been made in this investigation to define the conditions under which ammonium nitrate (AN) might detonate as a result of involvement in fire. The initiation of detonation by shocks derived from explosives or from projectile impact was investigated as a function of temperature and charge diameter. A new technique was devised to investigate the burning of raw and contaminated AN under pressure. No transition, to detonation in AN was obtained in the burning experiments. The critical diameter for detonation of fertilizer-grade AN was found to be quite small when the AN was at temperatures just below melting point; this indicates that initiation of detonation may be less difficult at elevated temperatures but such initiation by gas-phase detonation was shown to be unlikely. Transition from burning to detonation was obtained with AN intimately mixed with fuels that included polyethyl-ene, paper, and fuel oil when these were contained in vessels with restricted vents. However, the experimental results supported by an analytical study indicate that the initiation of detonation in AN from fire exposure in normal storage and from transportation incidents is quite improbable. The detonation of AN in recent incidents more likely may have resulted from the effects of adjacent explosions.

Jan 1, 1966

By R. T. Jones

"Technical publications in the field of mining and metallurgy have existed for a long time. Recent developments in electronic publishing on websites make it possible to disseminate information more widely and cost effectively than before. Professional societies have an opportunity to serve their members and their industry by publishing high-quality peer-reviewed papers on their websites as well as in printed form. Older publications can be scanned, and optical character recognition can be used to provide searchable text. Various business models exist around this process. This paper outlines the approach used by the Southern African Institute of Mining and Metallurgy (SAIMM) to provide free open access to their journal papers and conference proceedings, as well as the work being done by OneMine.org to collect technical papers from a number of international societies and make them available to subscribers via a large database. An approach is outlined that should be of benefit to authors, readers, and society at large.INTRODUCTIONGeorgius Agricola (1494-1555) was not the first writer on the subjects of mining and metallurgy, but is well known as the author of De Re Metallica (‘of things metallic’ or ‘on the nature of metals’), a book that documents and illustrates the observations he made in the course of his extensive travels in the 1500s. Agricola wrote extensively about mining methods and metallurgical processes that were in place in the Middle Ages. The original Latin version of De Re Metallica was published in 1556, the year after Agricola died. It was translated into English by Herbert Hoover, a mining engineer and later President of the United States, and his wife Lou Henry Hoover, a geologist and classicist. The English version of De Re Metallica was published in 1912."

Jan 1, 2012

By Arthur Barnes, Mika Muinonen, M. J. Lavigne

"The carbothermic reduction of chromite ore to produce high carbon ferrochromium is among the most energy intensive metal extraction processes performed, due not only to the highly endothermic nature of the reduction reactions but also the very high operating temperatures required for the smelting operation to separate the chrome-containing alloy from the discard slag.KWG Resources and XPS have collaborated over the last 3 years in developing a patented (Winter) processing alternative to the traditional smelting operation in which all processing takes place in the solid state at temperatures many hundreds of degrees lower than those required for liquid processing. Amongst the attractions of the process are much lower capital costs, as well as reduced operating costs, particularly of energy.A techno-economic study on the new process identifies a reduction in overall energy consumption of 70% against conventional processing and approximately 40% lower than the current best practice. By utilising more natural gas than coal based energy sources, the KWG process is able to show an overall 50% reduction in greenhouse gas emissions compared with the most energy efficient current practice. The impact of the new process on future processing is therefore regarded as highly significant, with global energy reductions equivalent to the effect of completely eliminating energy demand from a country the size of Italy.The study concluded that the potential for this process to completely revolutionise the global ferrochrome industry should not be underestimated. Its impact reaches far beyond exploitation of a regional natural resource."

Jan 1, 2015

By S. G. Hardcastle

The effects of air velocity in promoting cooling through the evaporation of sweat generated when working at a high metabolic rate and/or in hot environments is well known. Many of the environmental heat stress indices consider the effect of air movement directly or indirectly within their determination, be it through the use of a specific instrument i.e. a wet-bulb globe temperature meter or Kata thermometer, or inclusion of in the calculation of a stress index, including the effective temperature, air cooling power, thermal working limit, ISO 7933?s predicted heat strain model. Within these models, ambient air temperature, relative humidity and barometric pressure are also considered in varying degrees to quantify an airstream?s capacity to evaporate sweat. Deep mine studies have shown cumulative increases in heat exhaustion rates with both decreasing air velocity and decreasing air cooling powers. However, despite a capacity to cool, the resultant cooling is very dependant on sweat production and its availability for evaporation; these are included where sweat rates and skin wettedness are considered. The first depends on hydration and physiological factors whereas the second is more an engineering factor related to the degree of clothing required. As sweat rates deteriorate with aging, the benefits of evaporative cooling potential can similarly be expected to be diminished. This paper continues to report upon on-going physiological studies exploring the potential for heat stress in deep underground mines through the simulation of mining activities in environmental chambers and a human calorimeter facility. The focus of this paper is to introduce preliminary data suggesting that increasing air velocity (0.5, 1.5 & 3.0 m/s) is beneficial for young subjects (22 ± 1 yrs), as indicated by lower core and skin temperature measures and heart rate during an intermittent work protocol, and then show a lesser benefit for older subjects (62 ± 2 yrs). Both subject groups performed the same task under the same environmental condition (35°C, 60% RH) wearing a standard mining ensemble. The study similar to others being performed under the Deep Mining Research Consortium funded research continues to provide evidence that a greater understanding of heat management processes is required and that worker education is critical as environmental measures and health and safety regulations may not be expected to include all demographic factors such as age, sex and health which are known to affect human thermoregulatory response.

Aug 1, 2013

By John W. Straton

Following the completion of the paper presented in February, 1972, data were received from many other mines and some original respondents submitted more complete questionnaires. The computer program was changed to permit the results to reflect more clearly all the data reported by the mines. The original paper was revised to reflect the new information. There were significant changes in some numerical values, particularly where the size of the sample changed appreciably. Some limited samples considered originally in arriving at conclusions were not relied on in this revision. The revised tables and text are of the same design and format as the original paper.

Jan 1, 1972

Large deposits present computational challenges to todayÆs commercial orebody modelling systems that are based on conventional block models. We describe a system that is specifically engineered to model and visualise large deposits. Central to the system is linear octree encoding of conventional block models and real-time conversion of three-dimensional (3D) meshes to linear octrees. We provide both methodological treatment and practical experience in implementing such a system. A commercial implementation is also presented to demonstrate the validity of the approach.

Sep 26, 2011

By Egbert Burchardt

"Some of the challenges faced by the mineral industry in the future are the need to process low grade ores at the lowest operating cost, to deal with elevated energy cost and to address scarce water resources in some regions of the world. These challenges will increase the demand to develop highly energy-efficient and less water-consuming mineral processing systems. Experience from other industries suggests that HPGRs could help to achieve these goals, due to their high energy efficiency and their ability to be used as dry grinding systems. Historically, HPGRs have been used mainly as tertiary crushers in mineral applications for the production of ball mill feed. In the cement industry, however, HPGR systems have been successfully applied for grinding limestone, clinker and slag to a final product fineness (p80) of between 30 and 90 µm without the need of downstream ball milling. The total energy consumption of HPGR finish grinding systems in the cement industry has been found to be 30 to 50 % lower than in ball mill systems. This leads to the question of whether the same methodology can be adopted in the mineral industry. Such a step would require the use of dry rather than wet grinding systems. Traditionally, dry grinding systems have been only an exception in mineral processing, since most post grinding processes are wet. However, there are successful - mainly ball mill based - dry grinding examples in gold, nickel or iron ore. Experience from some of these dry grinding references are summarized in this paper. In addition, this paper explores two future-orientated questions: What opportunities does HPGR finish grinding offer the mineral industry? What are general conditions and challenges for adopting this technology for mineral applications?"

Jan 1, 2014

By Thomas L. Kesler

Lithium raw materials usable with present technology consist of pegmatite ore and surficial evaporite brine. Those advantageously located now supply world markets. Materials of similar grades and magnitude, but less favorably located, will come into production as present sources are depleted and markets expand. Some of these potential supplies have been explored, and are reserves in the sense of known availability and quality. Reserves herein are of two classes, those proved by close drilling and assaying, and those of only probable status because their scale and grade are unsystematically indicated. Possible resources include similar materials whose bulk can only be inferred on indirect evidence. All figures apply to total materials in the ground. No allowance is made for losses in mining, evaporation, beneficiation, or chemical processing.

Jan 1, 1977

By O. M. Wicken

Magnesite has the unique combination of properties that make it useful in a wide variety of metallurgical applications. The use of refractory magnesite has been increasing throughout the world, but the source of the "ore" differs. The United States has increased production of synthetic magnesites while the rest of the world is exploiting its resources, using natural magnesites. The history and methods of manufacturing synthetic magnesite are discussed as well as the practices for beneficiating natural magnesite. The properties, costs, and uses of the two types of magnesite are discussed and compared.

Jan 1, 1964

By M S. Fenzel

Increased environmental regulations and pressures have created changing and new demands for tailings management strategies in a variety of mining applications. Critical among these items is the disposal of tailings as the pursuit of increased yields and lower costs have driven the application of different process technologies. With a number of technologies having a niche application focus, the belt filter press has been utilised for decades as a cost-effective and versatile option for dewatering different types of mineral tailings and other waste process streams. One of the critical advantages of the belt filter press is the technology’s ability to adapt and work in numerous plant designs, operating conditions and applications. As permitting and disposal options have become more stringent, plant designers, operators and equipment suppliers must develop comprehensive and site-specific economic, design and process evaluation techniques to ensure proper equipment selection and system design for belt filter presses or any other dewatering technologies. This paper will explore these techniques in relation to belt filter presses (with reference to other technologies) in a variety of different applications, along with other considerations to ensure a successful tailings dewatering system and disposal design. Summaries of equipment performance characteristics, operating and maintenance strategies and optimisation techniques will also be addressed in conjunction with the belt filter press’s adaptability to different plant designs and the resulting tailings characteristics.CITATION:Fenzel, M S, 2015. Analysis and adaptability of belt filter presses and other technologies for tailings dewatering over a range of mineral processes, plant designs, conditions, regions and operating philosophies, in Proceedings Tailings and Mine Waste Management for the 21st Century , pp 35–44 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015