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By Eddy J. Jacques

When the automatic control of a ventilation process is considered, and supervising expert systems need to be designed, an important problem to address is: what will be the optimal set points of the regulators that should meet a certain number of independently formulated requirements, distributed over a ventilation network? The set of these requirements, expressed in terms of air flow quantities or differential pressures in certain airways, need not be consistent. Their number is not limited by the number of available regulators, nor by their nature, i.e. passive or active. Moreover, they may be subject to upper or lower limit values. The method described here addresses this problem and tries to provide a tool that should allow to calculate the set points of all the regulators as a global and optimal solution with respect to this set of distributed requirements. The pure mathematical developments in this paper are kept as short as possible in order to allow more room for the description of a relevant example.

Jan 1, 1991

By J. -B. C. Varnier, J. A. Cremeens, D. D. Overton

"Slope failures that occurred in 2008 and 2009 at the Pikeview Quarry in El Paso County in Colorado in the United States were investigated using three-dimensional discrete element modeling methods. Large-scale block sliding failures occurred along weak bedding planes that dip steeply into an excavation located at the toe of the slope. Several mining sequences at the toe of the slope were simulated to evaluate the effects of various degrees of extraction and backfill on slope stability. Slope stability back-analysis was conducted using prefailure and post-failure conditions to determine the joint shear strength properties. Laboratory testing was also conducted to determine intact rock properties. Three-dimensional discrete element analysis was uniquely applicable to this evaluation because it allowed representation of shear stress of the basal sliding surface and afforded evaluation of several scenarios of extraction and backfill at the toe of the slope. IntroductionThe Pikeview Quarry is an aggregate quarry located approximately 8 km (5 miles) northwest of Colorado Springs in El Paso County, CO, USA. The quarry has been operated by several owners since the early 1900s. According to the U.S. Mine Safety and Health Administration (MSHA, 1986), the quarry has been a major source of construction aggregate for the Colorado Springs area for many years. In the 1950s, the site was mined by Peter Kiewit and Sons to provide limestone for the construction of the nearby Air Force Academy.A large-scale slope failure occurred on Dec. 2, 2008, which stopped mining activity at the Pikeview Quarry. A second, related slope failure occurred on Sept. 13, 2009. The second slope failure was located immediately adjacent to the initial December 2008 failure.The objective of this paper is to discuss the three-dimensional slope stability evaluation. The causal relationships of slope instability are not within the scope of this publication. However, omitting the precursors to slope failure would limit understanding of the nature of the slope stability evaluation. The regional and local geology and the history of slope instability at the Pikeview Quarry aid in understanding these precursors. Two main failure mechanisms were hypothesized during the failure investigation to explain the triggering of the 2008 and 2009 large slope failures at the Pikeview Quarry, and both of these mechanisms were given equal credence in the present study. Quarry excavation and backfilling was a key factor in the slope instability for both failure mechanisms. The excavation was backfilled in stages in an effort to provide slope support. The objective of the three-dimensional model was to evaluate the effects of extraction and backfill at the toe of the slope with respect to slope stability."

Jan 3, 2018

By Tsutomu Yanagase

Non-ferrous smelting industry in Japan often had the severe problems about the over production of sulfuric acid. There has been such a closed relation between amount of sulfuric acid from non-ferrous smelting industry and the products of copper, zinc and lead metals that the production of one ton of copper accompanies three tons of H2S04. When the proper balance exists in both markets this situation certainly brings bigger profits. In Xining and Metallurgical Institute of Japan the research commitee concerned with the fixation process of sulfur in non-ferrous smelting industry was established in 1977 and continued the activity for four years untill 1981. This paper will introduce some of the activities involved in the report published by the committee.

Jan 1, 1982

What is your personal view and assessment of the overall health of the industry in the current global economy? The economic outlook remains soft for the near future and, although the global economy is showing signs of recovery, uncertainty has tempered the pace of recovery. In addition to uncertainty, we are still facing significant economic challenges in many parts of the world, including Europe and the United States. The rapid expansion of China?s economy has recently slowed, further contributing to the sense of uncertainty in the overall health of the global economy. This situation is both a blessing and a curse, depending on which sector of the mining industry we are considering. For example, coal, industrial minerals, aggregates, base metal and precious metals markets are impacted by different forces and drivers and will experience different outcomes within the same economic environment. Let me give a few concrete examples to illustrate this concept. The prevailing economic uncertainty that I have just described tends to drive investors toward safe havens. Gold has historically been viewed as a safe haven and as long as investors shy away from traditional investments, gold prices will remain high and gold mining companies will continue to expand and invest capital in their operations. The same sluggish economy that drives gold prices higher has the opposite effect on other segments of the minerals industry. A great example of this is industrial minerals and aggregates used in construction. The markets that consume these minerals have contracted significantly over the past five years. The outlook for this segment is poor, as the glut of available housing continues to inhibit demand for new construction and, thus, many industrial minerals. In addition to this, the federal government?s lack of political will to enact long-term legislation funding transportation and infrastructure projects continues to be a drag on the U.S. aggregates industry.

Jan 1, 2013

By Shawn P. Coughlin, Michael A. Schimmenti, Juan Leonardo Tello del Pino

"The Sistema de Potabilización Área Norte project (Northern Area Purification System) was a major expansion of the potable water system in Buenos Aires Province, Argentina. The aim of the project was to transport and purify raw water from the Paraná River to provide potable water for five communities in the northern part of the province, benefitting up to two million people. The project was constructed by a joint venture (JV) of four South American contractors and consisted of the following key components:• Treatment plant: A 16-ha (39-acre) area was cleared for the construction of a treatment plant to purify 900,000 m3/day (1.2 million cu ft/d) of raw water from the Paraná River and distribute it to the surrounding communities.• Bored tunnel: Nearly 15 km (9 miles) of 3.6 m (12 ft) inner diameter tunnel, ranging from 18 to 22 m (59 ft to 72 ft) below grade, was bored with two earth pressure balance (EPB) tunnel boring machines (TBM) to draw the raw water from the river. The TBMs started from a central launch shaft and proceeded in opposite directions. Cristina advanced northbound to the Paraná River Intake System, and Liliana advanced southbound to the new treatment plant.• Access and ventilation shafts: Five access shafts and eight ventilation shafts were installed along the length of the tunnel. The access shafts were designed to provide entry points for inspection and maintenance of the final tunnel. The five shafts consisted of one central launch shaft in the middle of the tunnel alignment, one retrieval shaft at each end of the tunnel (intake and treatment plant, respectively) and two intermediate shafts. The intermediate shafts were installed before the TBM passed, with a final liner to be installedafterward."

Sep 1, 2016

By Chris Howell

PotashCorp?s Aurora phosphate mine, in Beaufort County, NC, operates four low pressure boilers and four high pressure boilers to meet its process steam requirements. Maintaining these boilers is critical to meeting production demands. Processing phosphate ore into phosphoric acid requires large amounts of sulfuric acid and steam. Ore is mined from the phosphate deposit with large bucket excavators after 9 to 30 m (30 to 100 ft) of overburden is removed. The phosphate ore is mixed with water to make a slurry that is pumped to the mill. Elemental sulfur is burned in the presence of air to make sulfuric acid. This process is highly exothermic and boilers produce steam while cooling the process. The phosphate ore is reacted with sulfuric acid and the resulting products are refined into different grades of phosphoric acid for fertilizers, feed stock and food additives. Plant operators at the mine were challenged with boiler feed water that was high in silica and other contaminants. As a result, boiler operations were experiencing difficult, labor-intensive operations and equipment deterioration. This resulted in higher operating costs and diminished processing performance. The facility was operating an aged boiler feedwater pretreatment system that included warm lime softening followed by pressure filtration and a cation/anion/mixed bed demineralizer system. The demineralizer required frequent regeneration and chemical usage was high and costs were difficult to predict. Depressurized well water (DPW water), used for plant utility water and boiler makeup, is very high in silica, in the range of 60-70 ppm. Silica can form scale at pressures below 600 psig. Above 600 psig, silica starts to volatize, carrying over with steam to potentially form deposits on downstream equipment and processes. Mine officials decided to upgrade the boiler feedwater pretreatment system to a state-of-the-art reverse osmosis (RO) membrane system. This new system, which started up in March 2009, has improved operating performance and reduced water consumption and overall operating expenditures.

Jan 1, 2011

By M. Ghiani

Biohydrometallurgy originated, some forty years ago, from an environmental problem, namely the serious pollution of the Ohio river by acid drainage water coming from neighboring subbituminous coal mines. Studies aimed at elucidating the cause of the intensive oxidation of the iron sulfide (pyrite) inclusions of those coals, led to the discovery of a bacterium, Thiobacillus ferrooxidans (Temple and Colmer, 1951), capable of acting as a catalyzer, accelerating the otherwise very slow chemical oxidation of iron sulfide to rates many orders of magnitude higher. However, it is now recognized that the biotechnology of microbial mining dates back to 1963, when the ability of this bacterium to solubilize copper from sulfide ores was ascertained (Razzell and Trussell, 1963). Much research has been carried out on biohydrometallurgy over these last 25 years and is still being actively conducted all over the world. The interdisciplinary nature of this young branch of science and technology is reflected by the variety of experts involved: microbiologists, mining engineers, hydrometallurgists, physico-chemists, mineralogists, solid-state physicists and biochemists. This intensive research effort has provided a solid background on the fundamentals of this technology, although many important issues have still to be solved, amongst which the enzymatic mechanisms controlling biocatalysis of mineral sulfides dissolution, the influence of bulk- and surface solid-state physics of metal sulfides on dissolution mechanisms, the interaction of the various strains composing natural microbial floras. Their elucidation should permit the rationalization of biohydrometallurgical techniques and the optimization of commercial processes. Biohydrometallurgy has already achieved satisfactory results: copper recovery from submarginal copper sulfide run-of-mine ores (i.e. assaying less than 0.3% Cu) by in-situ, dump and/or heap leaching is successfully practised in many countries and uranium recovery through bioleaching is competitive with other leaching processes.

Jan 1, 1987

By William C. McBee

A sulfur concrete technology has been developed by the U.S. Department of the Interior, Bureau of Mines, in which chemically modified sulfur is utilized with suitable mineral aggregates to produce construction materials which are resistant to corrosion by acids and salts. This report presents a summary of the basic technology and results of testing the materials under actual operating conditions in 50 corrosive environments in 40 commercial plants. After 4 years of testing, there was essentially no evidence of material degradation or loss of strength. Regular concrete materials were attacked and in some cases completely destroyed under the same conditions. Testing is continuing to establish ultimate longevity and durability of the sulfur concretes. The materials are finding widespread applications in metallurgical, chemical, and fertilizer processing plants.

Jan 1, 1983

By L. Adler

INTRODUCTION The purpose of this paper is to describe in engineering terms the singular and basic operational kinematics of all excavating and bulk handling equipment. The safe and efficient use of equipment will be fostered by enabling the engineer to conceptually duplicate the operators' "tasks" in directing and controlling it. A simple graphical and notational scheme will be introduced to define the essential gross repetitive motions. The significance of this effort includes filling a vital analytical gap at the work face, and in establishing direct communications between the engineer and equipment operator. Since all types and sizes of earth- moving equipment are covered, a major concern has been to integrate equipment specialties into d single encompassing discipline. Equipment types are closely related to the working conditions, and their selection and evaluation are also considered. The extension to human factors analysis is natural and predictable. Since human [actors are involved, the operational analysis can also be considered a catch-all for many subtle vagaries. BACKGROUND Symbolic modelling linked to a notational system will be developed and intensively used. This constitutes the "language of science," providing a shorthand method which gives immediate recognition, is fluent, explicit, reinforcing, unequivocal and provides limitless associations. Many examples of symbolic modelling exist in chemistry, physics, the military, engineering sciences and it is a major tool in mapping. Its use is so ubiquitous that it often goes unnoticed. On the other hand it must be realized that something is lost in simplifying and idealizing what is an extraordinarily complex occurrence. The components describing the basic operational kinematics of equipment include: (1) the vehicular motions as a rigid body and (2) the job-end motions focussing on excavating (Adler, 1985). These provide all of the components in the load-haul-dump sequence (L-H-D) , and will yield three dimensional expressions. Complex patterns can also be assembled from these simple elements. An existing equipment designation employed in earthmoving will be integrated into this approach (Carson, 1961). Along with the basic motions, corresponding working conditions will be noted.

Jan 1, 1986

By R. Hogg, T. F. Dumm

With increasing interest in the physical cleaning of fine coal, there is a need for extension of the sink-float analysis procedure to finer sizes. Problems arise, however, in ensuring complete dispersion of the particles in the heavy liquids. A procedure has been developed in which surfactants are wed as dispersing agents, and solids concentration is minimized (using a simple formula to estimate the minimum weight needed for statistical reliability). Using centrifuges to increase separation rates and subsieve particle size analysis of the specific gravity fractions, a complete size-specific gravity distribution can be obtained. Analyses have been performed on coal samples as fine as - 10 µm.

Jan 1, 1987

By Arthur S. Cornford

According to Arbiter (Reference 1), the ball mill was invented by Brückner in Germany in 1876 and was first used in the United States on ores about 1905. The basic concept was a simple rotating cylindrical drum in which the tumbling action of the charge of material and grinding media resulted in size reduction of the material. Despite the very low mechanical efficiency of this method a number of factors have caused the tumbling mill to remain, by far, the most widely used piece of equipment for mineral grinding. The principal factors influencing this situation have been simplicity of design, ease of manufacture, ready adaptability to familiar material handling layouts and the absence of practical alternatives acceptable to the industry. In the early mills, the material was ground in batches, the mills being charged and discharged through doors in the shell. The shell was supported by means of solid trunnion shafts resting in plain bearings and the drive was accomplished through one of these shafts. In some later batch mills, the mill shell was supported on rollers which were also used to drive the mill. At an early stage, continuous operation was made possible by feeding and discharging the mill through hollow trunnions, the method still in most widespread use. The mechanical and structural design of the early mills was not an onerous engineering task. Norse sense and good practical knowledge were key qualifications. The mill shells had to be heavy enough to withstand the physical abuse they would receive in the field and the bearings had to have low enough unit pressures and sufficient wear retol to ensure several months of operation before the need for replacement occurred. When these requirements were satisfied, stresses developed in the equipment during operation were insignificant and the majority of structural failures were probably due to the use of inferior materials in manufacture. Over the years, the ever present demand for increased productivity has resulted in a steady Increase in the size of units of production equipment, including grinding mills. Arguments have been presented elsewhere, for and against the Idea of a high throughput single line grinding operation as opposed

Jan 1, 1972

By Gao Zhizhong, Zheng Shibo, Gu Zhengxing

Extensive research on the beneficiation of Florida dolomitic phosphate pebble has been carried out by Lianyungang Design and Research Institute of China (CLDRI) in recent years. Test results indicate that the fine-particle flotation process could be used to effectively recover the phosphate values from Florida high-dolomite phosphate resources. With the CLDRI fine-particle flotation technology, a phosphate concentrate with 31% P2O5 and less than 1% MgO could be obtained from a flotation feed containing 25.8% P2O2 and 2.2% MgO at an overall P2O5 recovery of up to 85%.

Jan 1, 1999

By D. M. Bodily, R. Jin, W. Hu

Four methods to assess the relative floatability of fine coal have been tested: flotation with frother only, salt flotation, timed-release analysis, and flotation with frother and collector. A practical and simple criterion that combines the separation efficiency (capacity factor) and kinetic rate constant (intensity factor) has been suggested. Five coal Samples from Utah were tested. Based on test results, it was concluded that the floatability test with collector and frother is closer to practice, and according to the suggested floatability criterion, coal fines can be classified into four categories of relative floatability: very easy, easy, moderate, and difficult.

Jan 1, 1988

By J. K. Mokka, P. D. Rao, H. K. Lin

Extensive exploration has resulted in delineation of a massive sulfide district on the north flank of the east-central Alaska range. The district covers approximately 400 mi2 and contains numerous stratiform, transposed and some replacement type sulfide deposits ranging in size from less than 1 million st to 20 million st. Five types of ores were sampled for the study. Mineralogical analysis revealed that the minerals are too fine grained for conventional grinding and beneficiation. Hydrometallurgical studies were conducted using ferric chloride as a lixiviant. Ore microscopic studies as well as electron microprobe analyses of minerals in the raw samples and leach residues explained the low recoveries for certain elements as well as sources of impurities that need to be eliminated from the process streams.

Jan 1, 1992

By Kenneth S. Graham, S. C. Gambrell

A short term, simple roof bolt load cell which uses a birefringent (photoelastic) coating as its sensing element has been developed. The load cell is installed between the bearing plate and the nut/washer and measures the initial force after installation by the bolting machine. The load cell can be removed from the bolt and used again to measure initial force in another bolt if desired. Because temperature and humidity changes in the mine cause creep/relaxation of the coating and/or adhesive, the load cell is useful for accurately measuring force for a period of only two weeks after installation. Force in the bolt is determined by referring to a calibration curve for the load cell.

Jan 1, 1992

By K. Lapakko

Kinetic tests results are influenced by methodological variables, including test duration and mine waste particle size. Some samples tested produced neutral drainage in kinetic tests for more than two years prior to drainage acidification. The potential for long "lag times" can be assessed based on the mine waste mineralogy. The lag time duration can be estimated using this mineralogy in conjunction with dissolution rates observed in the kinetic tests. The influence of particle size on the drainage quality is dependent on the variation of the availability of acid-producing and acid-neutralizing minerals with particle size.

Jan 1, 1998

By R. B. Krog

The use of belt air as an intake source at longwall operations has changed greatly over the past decades. The practical considerations for the use of belt air are controlled by a variety of factors, including airflow quantity and velocity, coal methane content, methane desorption rates, coal mining rate, belt length, stopping leakage and the number of gateroad entries. At longwall operations, the advantages and disadvantages of belt air are different than for gateroad development and longwall panel extraction. During gateroad development, the use of belt air to ventilate the working section will reduce the leakage from the intake to the belt compared to the belt air being ventilated outby the working sections because of lower pressure differentials. A greater quantity of airflow will reach the last open crosscut with the belt on intake than outby, given the same amount of pressure and airflow available at the mouth of the section. This paper will investigate the current ventilation practices regarding the use of belt air during gateroad development and longwall panel extraction. Operating considerations regarding air quantities and pressures to deliver the required airflow will be investigated using ventilation network modeling.

Jan 1, 2010

By A. Tarigan

The integration of the ESZ orebody and DOZ orebody resulted in a much larger footprint than the original DOZ Mine shape. The significant change in footprint geometry presented new cave front management challenges, specifically: longer undercut drifts. Using a constant blasting rate, more time is required to complete caving in each drift which ultimately influences the number of active faces at any point in time. The number of manageable active drifts is controlled by the planned square-meters of undercut blasting, lead/lag restrictions and other specific conditions such as the need to blast pre-charged explosives. In early 2008, an evaluation of the existing plan showed that significantly more active undercut drifts and longer cave fronts would occur in the next five years. Difficulties associated with the long cave fronts led to a decision to redesign the caving sequence. Several different boundary options based on operational, geotechnical and ore grade parameters were investigated. This paper describes the issues faced with long cave fronts, the constraints and requirements to effectively manage the caving sequence and the options considered to mitigate this situation.

Jan 1, 2010

By Sakshi Hazuria Anderson, Angela Binder, Oscar Jaime Restrepo Baena, Simit Raval, Sandra Nowosad

As the mining industry faces times of change, new challenges arise to ensure raw material supply for the younger and future generations. Different scenarios are currently shaping the way we mine and teach mining engineering. Led by an increasing demand for raw materials, net zero requirements for improving long-term operation performance, technological advancements such as automation and digitalization, safety improvements, environmental considerations and a need for social acceptance, mining is pursuing to change and adapt to these requirements at a faster pace. Such changing times raise new concerns, one of the most relevant is the lower number of students interested or enrolling in mining engineering and related fields leaving mining engineering as one of the less preferred career options between the younger generations. Nonetheless, it is essential to continue addressing and supplying the skill sets that are suited to the contemporary and future mining industry. To this end, globally, academia is currently undergoing several initiatives such as curricula updates and adaptation, up skilling, improving teaching practices and techniques, including e-learning techniques, enhancing industry-academia and inter-university collaboration, and much more. In countries like Australia, where mining plays a crucial role in the economy, the need for curriculum updates is more pressing than ever. As the mining industry evolves with new technologies and sustainable practices, there is a growing demand for a workforce skilled in these modern approaches. Recognizing this necessity, universities such as the University of New South Wales and Curtin University have taken significant steps to revamp their educational programs. By updating their academic offerings, both universities aim to equip graduates with the necessary skills to drive innovation and sustainability in mining, supporting Australia’s development as a leader in this critical sector. Moreover, the selection of topics that drive curricula update and the focus of the research institutions in mining engineering must extend beyond mere technological and technical aspects to include social and ethical dimensions. In this context, the Universidad Nacional de Colombia, in association with the Colorado School of Mines, has introduced the topic of Humanitarian Engineering (HE) in 2020. HE is a socio-technical approach that focuses on developing engineering solutions that promote the sustainable development of communities addressing their basic needs and aiming to improve their quality of life (10, 18). By focusing on sustainable development, community engagement, and equitable resource distribution, HE helps the industry build positive relationships with stakeholders, reduce conflicts, and foster social license to operate. As the mining industry seeks sustainable and socially responsible practices, future engineers require training in this area to understand the broader impacts of their work, fostering a mindset that prioritizes community well-being and environmental stewardship alongside technical proficiency.

Feb 1, 2025

By D. K. DeForest

The olfactory system (sense of smell) is crucial to the ability of fish to avoid predators, recognize kin, and synchronize reproduction (Baldwin et al. 2003). Copper (Cu) has been shown to impair olfaction in juvenile freshwater life stages of salmonids (including Pacific salmon and trout) in some laboratory experiments; and in the United States, public concerns have been expressed that current regulatory criteria for Cu in fresh water are not adequately protective of olfactory function in salmonids (e.g., OSU 2007; Pearson 2007). These concerns have largely been raised because some Cu concentrations that have caused olfactory impairment in salmonids in the laboratory are less than Cu concentrations that have been shown to reduce salmonid survival, growth, or reproduction (the effects endpoints that are typically considered in deriving ambient water quality criteria). However, two important and interrelated points that must be considered: (1) freshwater Cu criteria are "driven" by the sensitivities of several invertebrate species that are more sensitive than the olfactory impairment threshold in salmonids when (2) the influence of water chemistry on Cu bioavailability is properly considered in deriving Cu criteria. Bioavailability refers to the ability of various chemical forms of Cu to interact with receptors on the surface(s) of organisms and thus directly cause toxicity or uptake by the organisms. The toxicity of Cu and other metals to aquatic organisms is a function of water chemistry. For example, acute Cu toxicity in fresh water generally decreases as pH, water hardness (Ca2+ and Mg2+), alkalinity, and dissolved organic carbon (DOC) concentrations increase (Meyer et al. 2007). The U.S. Environmental Protection Agency (USEPA) has recommended hardness-based freshwater aquatic life criteria for Cu and other metals since the 1980s (e.g., USEPA 1985); and hardness-based metals criteria decrease (i.e., become more restrictive) as water hardness decreases. More recently, the USEPA has recommended freshwater aquatic life criteria for Cu based on the biotic ligand model (BLM; USEPA 2007), which accounts for the influence of multiple water chemistry parameters, including DOC, pH, alkalinity, Ca2+, Mg2+, and several other cations and anions. The BLM-based Cu criteria generally decrease as DOC concentration, pH, alkalinity, and water hardness decrease. Because DOC has a stronger influence on Cu bioavailability than water hardness, hardness-based and BLM-based Cu criteria can differ considerably. For example, in water that has low DOC and high hardness, the hardness-based Cu criterion would be relatively high (because it is driven by the high hardness) but the BLM-based Cu criterion would be relatively low (because it is driven by the low DOC). Thus, any evaluation of the protectiveness of Cu criteria against a given effect, such as olfactory impairment, must properly account for the chemistry of the exposure water. Meyer et al. (2013) compiled data on Cu-induced olfactory impairment and olfactory-induced behavioral effects from tests in which BLM parameters were measured. They demonstrated that the USEPA's BLM-based freshwater life criteria for Cu are protective against olfactory impairment, because it adequately accounts for water chemistry (whereas the USEPA's hardness-based Cu criteria are not consistently protective). Olfactory impairment by Cu is now receiving increased attention in Canada and Europe (e.g., Wall 2013; Stang 2013). Accordingly, in this paper we have expanded the analysis of Meyer et al. (2013) to consider copper guidelines from various other countries and whether these guidelines are protective against olfactory impairment.

Feb 23, 2014