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By H. Haselhuhn

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

Jan 1, 2012

By Carolina Vaghetti

Aliar qualidade do produto final e otimização dos custos de produção é o que toda indústria de componentes mecânicos almeja. Um dos problemas enfrentado na produção de eixos automotivos é o surgimento das distorções de formas, e saber as causas dessas distorções vem se tornando cada vez mais imprescindíveis. Dentre os processos de fabricação, o tratamento térmico é conhecido como uma etapa da produção que potencializa os efeitos dos potenciais de distorção acumulados ao longo da cadeia. As tensões residuais são consideradas um dos principais potenciais de distorção e, por isso, é de grande importância o seu entendimento. Sendo assim, o presente artigo, inserido no âmbito do projeto "Investigation and improvement of a manufacturing process chain from cold drawing processes to induction hardening", realiza uma análise das distorções e da distribuição das tensões residuais após a têmpera por indução e uma análise das tensões residuais após o processo de retífica durante a fabricação de eixos automotivos de aço ABNT 1045. Foram variados parâmetros nos processos de trefilação e têmpera por indução. A partir dos resultados obtidos, foi possível verificar a influência da profundidade de camada temperada, onde a maior camada apresentou, em média, maiores distorções.

Aug 16, 2017

By E Villaescusa, A Kusui, R Talebi, R Hassell, C Arcaro

Northern Star Resources (NSR) operates several seismically active mines as part of its Kalgoorlie Operations. In order to successfully continue mining at depth in increasing stress conditions, strategies need to be developed to reduce, control and manage the impact of seismicity causing damage to the rock mass. Consequently, a research partnership was developed with the WA School of Mines (WASM) through Mining3. The main aim of the project was to develop appropriate ground support standards that could withstand the expected dynamic response with minimal to no rehabilitation required for the life of that excavation. The project utilised a design methodology for determining the required energy demand based on detailed geotechnical mapping, probabilistic analysis of wedge formation and an estimate of rock ejection velocity based on uniaxial compressive strength of the intact rock (Villaescusa et al. 2016). The ground support scheme consists of high tensile chain link mesh, resin encapsulated de-coupled posimix bolts and plain strand cable bolts, in one, or multiple passes together with plain shotcrete. Implementation of the design posed several challenges including how to install the chain link mesh, maintaining the required productivity, ensuring quality control, and understanding the interaction of the several ground support components within the scheme. The implementation of the system within a trial area was successful from development mining to open stope extraction. The most significant field verification of the system occurred with near field M+1.9 seismic occurring in proximity to an operating long-hole drill. Despite large displacements exceeding 0.5m in places, there was no significant ejection of rock or failure of the ground support system. Following the successful trial, the ground support design methodology and standards have been implemented across several NSR sites. The system forms the basis for the successful extraction of resources in future high seismic risk areas.

Mar 15, 2021

Blasting, particularly bench blasting, uses finite length cylinders of explosive close to two free faces. The rock to be blasted is usually intersected by a complex 3-D system of joints. To fully simulate a blast, a 3-D dynamic model is required. It is shown that the static stress distribution around a long cylinder can be reproduced by superposing the static stress distribution of a suitable chain of spheres. Thus, the dynamic results for individual spheres given by Favreau (1969) can now be substituted for the static results to give a dynamic model of the stress distribution around a long cylinder. Comparison of measured and computed waveforms show that the measured waveforms are much more attenuated and dispersed than expected. The consequences for explosive evaluation and design are Discussed.

Jan 1, 1990

By Forest J. Sur

"This report describes an exploratory project conducted by the Bureau of Mines on a fluorite deposit near Vado, N. Mex. Results of trenching are given. Together with analyses made upon samples of the ore. The Federal Geological Survey3/ completed a preliminary geologic study and mapped the deposit during the summer of 1944. A Bureau engineer examined the deposit in August 1944. As a result of these investigations, it was concluded that the deposit contained substantial inferred ore reserves. Exploratory work was recommended to obtain information that might possibly lead to production from the property. Assistance was given the Bureau by the Geological Survey.A gasoline-powered air compressor, other equipment, and supplies were delivered to the property from January 20 to 25, 1943. Trenching began under the direction of a Bureau of Mines engineer on January 25, 1947, and ended on March 15, 1945. The results of trenching and sampling form he basis of this report.In its program of exploration of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. IT is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, R.G. Knickerbocker, chief, analyzes samples and performs beneficiation tests. Both these branches are under the supervisions of Dr. R. S. Dean, assistant director."

Sep 1, 1946

By Earl R. Hoskins, James E. Russell

The electrical resistivity of rocks has been studied quite extensively, in particular, the effects of temperature and confining pressure on resistivity. References 1 through 6 at the end of this chapter pertain to electrical resistivity of rock and contain further references on the same topic. The present study is motivated by an interest in determining the in-situ properties of rock as well as the stress state of the rock and how these quantities are changing with time. Most of the previous work on the electrical resistivity of rocks has been directed toward saturated rocks at relatively high confining pressures and temperatures. The present study was oriented towards air-dry surface rock that might occur in mine pillars. The mean stress and temperature under such conditions are comparatively low. It has been demonstrated that the resistivity of rock is highly dependent upon the porosity. In fact, for saturated rocks, a relationship referred to as Archie's law has been established between porosity and electrical resistivity. In the case of saturated rock, the property that is actually being measured is the resistivity of the solid/fluid system. Since the resistivity of the fluid alone is usually much lower than that of the dry rock, it is understandable that the resistivity of a saturated rock is in general several orders of magnitude lower than the resistivity of a relatively dry rocli. For dry rock, it seems reasonable that the electrical resistivity should increase as microcracks open within the material. Since microcracks open as material is stressed closer and closer to its failure point, it appears that there should be a correlation between electrical resistivity

Jan 1, 1970

Project-finance risk assessment is mature and approached systematically. Mining industry due diligence remains fragmented with specialists addressing different aspects of the project such as reserves/JORC, environmental impact, commodity market, even financial analysis/ modelling. Each professional has a natural tendency to believe that the risk factors they have examined are the key ones necessary to be reviewed, as if their review will stand in isolation from others in the way a project materialises. By first laying out the project risk categories and risk matrices, this paper examines the due diligence process with a keen eye to the risk assessment and overlap/interaction. Some cross fertilisation of due diligence techniques from other industry sectors is placed into the mining context. Six case studies are then presented with regards to due diligence features in each projectÆs feasibility review or financial information/ offering memorandum. A power case first shows the differences between the due diligence expectations of banks versus bond financings. Then some Australian and Indonesian mining development cases are analysed to see the due diligence learning points. Some of these were project/due diligence failures. The conclusion focuses on the value of a systematic risk assessment for project evaluation, all from the project-finance perspective.

Jan 1, 2007

By M. Drozd, M. Somppi, Z. F. Yamak

"Activated carbon is used to recover gold in solution from various gold circuit designs including carbon-in-pulp (CIP), carbon-in-column (CIC), and carbon-in-leach (CIL) processes; however, the characteristics and durability of the activated carbon can vary. Handling this medium poses challenges when fine carbon losses occur in the CIP, CIC, and CIL circuit discharge. Additionally, adsorbed gold on carbon fines can be lost to the discharge. The studies in this paper aim to standardize laboratory methods for testing activated carbon qualities specific to the gold industry. The investigation focused on size distribution, platelet content, wet attrition resistance, gold kinetics, and gold loading. The results demonstrate that a 96 h attrition test and a gold loading test form a basis for ranking carbon samples based on expected economic performance of the plant. ¦ KEYWORDS Activated carbon, Carbon attrition, Carbon ball-pan hardness, Carbon evaluation, Carbon fines loss, Carbon turnover RÉSUMÉ Le charbon actif sert à récupérer l’or en solution dans diverses conceptions de circuits de broyage d’or, notamment les procédés de charbon en pulpe (CIP, de l’anglais carbon-in-pulp), de charbon en colonnes (CIC, de l’anglais carbon-in-column) et de lixiviation au carbone, ou charbon au lixiviat (CIL, de l’anglais carbon-in-leach). Toutefois, les caractéristiques et la durabilité du charbon actif varient. La manipulation de ce milieu pose des problèmes dès lors que se produisent des pertes de carbone à grain fin dans la décharge des circuits CIP, CIC et CIL. Par ailleurs, l’or adsorbé sur les fines de charbon peut se perdre durant la décharge. Les études réalisées dans le cadre de cet article visent à normaliser les méthodes de laboratoire pour tester les qualités du charbon actif spécifiques au secteur de l’exploitation aurifère. L’étude portait sur la composition granulométrique, la teneur des plaquettes, la résistance au frottement humide, la cinétique de l’or et l’adsorption de l’or, à savoir la capacité du charbon actif à adsorber l’or sur une période spécifique. Les résultats ont montré qu’un test de frottement de 96 heures et un test d’adsorption de l’or constituaient le fondement d’un classement des échantillons de carbone du point de vue économique en vue de trouver l’échantillon générant le meilleur rendement des usines. ¦ MOTS CLÉS charbon actif, dureté de la batée des billes de carbone, évaluation du carbone, perte de fines de charbon, renouvellement du carbone, résistance au carbone INTRODUCTION The use of activated carbon for gold extraction is among the most common processes in modern gold-milling plants. Although gold losses are inevitable in the milling process, operators often focus on reducing gold loss to tailings. One focus area that is important in gold recovery is optimizing the use of activated carbon and examining potential changes to realize improved economics for carbon-in-pulp (CIP), carbon-in-column (CIC), and carbon-in-leach (CIL) processes. Granular activated carbon (Figure 1) is widely used for gold extraction from slurries containing gold-cyanide complexes. This activated carbon—produced from charred coconut shells—is well suited because of its adsorption kinetics, gold-loading capacity, attrition resistance, and ability to be reactivated. The extraction process using activated carbon technology involves adsorbing gold from an aqueous leachate; the gold is dissolved using a cyanide salt and consequently a dicyanoaurate(I) ion (Au(CN)2–) is formed, as noted in equation 1."

Jan 1, 2019

By N. Kumar Kittusamy

The purpose of this study was to assess the adequacy of the cab design and to determine the percentage of musculoskeletal symptoms among operators of mobile equipment used in mining and construction. A questionnaire was designed to assess demographics, work information, job history, and musculoskeletal symptoms in operators of heavy mobile equipment. Information concerning equipment included design of the seat/chair, levers, pedals, bothersome vibration, quality of ingress/egress from the equipment, proper preventative maintenance and repairs, and age of the equipment. The body regions that were evaluated included the neck, middle/upper back, low-back, shoulder/upper-arm, elbow/forearm, wrist/hand, hip, knee, and ankle/foot. Five hundred and eighty six operators completed the questionnaire. The results indicate that these workers are at risk for developing musculoskeletal disorders, and the need to quantify risk factors (i.e., whole-body vibration and static sitting postures).

Jan 6, 2006

By Kelvin K. Wu, George H. Gardner

On July 24, 2002, a nonfatal entrapment accident occurred at the Quecreek #1 Mine, Black Wolf Coal Company, when an active mining section inadvertently cut into a flooded abandoned mine. This incident, and the dramatic rescue which ensued, brought national attention to a common problem in the coal mining industry. Since 1995, there have been more than 100 inundations at coal mines in the United States. Unavailable, inaccurate, or incomplete mapping of older abandoned mines is typically responsible. Serious problems associated with accidental discharges of fluid mine waste material (slurry) and water from coal refuse disposal facilities have resulted from similar causes. Recent problems related to the inaccurate location of old abandoned mine works have increased the interest in the use of conventional and emerging drilling and geophysical techniques for detection of air-filled and water-filled cavities. The United States Congress has committed significant funding toward investigating the applicability of these technologies. MSHA actively promotes the use of the best available technology to minimize the significant adverse safety and environmental consequences associated with unplanned breakthroughs and inundations. This paper provides background information and a general summary of the MSHA-sponsored field demonstration projects which are currently in progress. Potential benefits and limitations are discussed. The need for field verification/ground-truthing is emphasized. Under appropriate conditions, geophysical methods can be effectively integrated into a comprehensive field exploration program.

Jan 1, 2005

By Rob Farnfield, Yuill Gavin

The rock blasting industry continues to be under pressure to reduce the level of vibration induced by the use of explosives. In recent years much research and development has been directed to minimizing vibration levels by controlling the delay period between blast holes. The most commonly applied technique is known as Linear Superposition. This technique takes the vibration produced from a single-hole test shot and simulates the vibration that would be produced from a full-scale production blast. The simulation can be run with various delay periods and the optimum delay chosen. The success of the Linear Superposition technique depends to a great extent on having accurate delay detonators and on the single-hole test shot reliably indicating the vibration signal produced from each hole in a production blast. A quarry-based case study is given illustrating how these assumptions are not always valid. In this case the use of electronic detonators has controlled frequency but not vibration level. The paper goes on to describe a series of single-hole test shots in an U.K. limestone quarry. The vibration 2 signals recorded are examined in terms of variations in free-face provision, blast geometry, explosive properties, etc.

Jan 1, 2001

By C. F. McCarroll

[Laboratory research and, control in the production an. utilization of petroleum and it 3 products have expanded greatly during the past decade, and much of the routine control and experimental equipment now rewires the constant daily use of liquid mercury. In spite of this ;;renter use, very little consideration has been given to the hazard that might be occasioned by the toxic vapors of mercury unavoidably spilled' of otherwise exposed to the atmosphere during the normal procedure of laboratory open at ions. A simple visual examination ).'.' son-,, r° the laboratories reveal the presence of a considerable quantity of mercury in the cracks of floors, on work tables, and on ark, around equipment stands. Usually this mercury is contaminated with oil3/ and dirt so that it remaining in a finely divided state and a ;mall amount pre presents a relatively large surface for evaporation. Since :mercury shows measurable volatility at a temperature v,.^ lo.! 5o F., mercury vapor will be present in, the mercury _3 exposed promiscuously.]

Jan 1, 1939

By W. M. Houston

The phosphate formations of the Pliocene epoch were deposited along the coastal shelf of the eastern seaboard. The deposition of the phosphate is thought to be somewhat contiguous along the early shoreline, and the deposit can be more or less traced over an 800 to 930 mile path from the Florida Gulf Coast, near Ft. Myers, to the Pamlico Sound of North Carolina. This is illustrated in Figure 1. Three areas of commercial importance are currently being exploited from this extensive known deposit: 1 - The so-called ?Bone valley? in Central Florida (multiple operations) 2 - Hamilton County in North Florida (Occidental Corporation operation) 3 - Beaufort County in North Carolina (Texas Gulf Sulphur operation)

Jan 1, 1966

By C. Jardine

The concept of the system is to minimize costly unscheduled breakdowns of equipment by replacing components earlier than their "life" expectancy. Periodic unit services are scheduled according to pre-set constraints. Service sheets are generated by matching a job and component master listing based on assigned cyclic component lives. The system can provide accountability of all man-hours reported and history information can be selectively retrieved. By reducing unscheduled equipment shutdowns, this system allows for better utilization of manpower and an overall improvement in equipment reliability and availability.

Jan 1, 1979

By A. P. Mehta

The role of microorganisms in the leaching of metal sulfides is well established (Torma, 1977; Murr, 1980). However, this established knowledge applies mostly to chemolithotropic microorganisms such as Thiobacillus ferrooxidans which function optimally in leaching catalysis between 25-35° C, and in a pH range of 2-2.5. Although leaching with thermophilic microorganisms capable of extending the range of catalytic viability beyond 35° C is also documented, there are few if any attempts to optimize or extend sulfide concentrate leaching with thermophilic microorganisms. When mixed metal sulfides or other materials having different rest potentials (referenced to the standard hydrogen electrode, SHE, in the electromotive series) make contact in a conducting, aqueous medium, the contacting members will act as an electrochemical cell, with the member having the higher rest potential assuming the role of an electrical cathode. In leaching reactions involving such galvanic couples, the cathode becomes passivated, while the anodic member reacts vigorously due to the electro- chemical reaction which occurs (Hiskey and Wads- worth, 1975). Serry, eta1 (1978) observed that when chalcopyrite and pyrite were in intimate contact in natural ores, the chalcopyrite reacted vigorously by galvanic conversion as a result of the higher rest potential (~ 0.63 V) as compared to the chalcopyrite (~ 0.53 V). In addition, it was postulated that because of the elemental sulfur which can form on the anodic chalcopyrite in this galvanic conversion process, reactions in acid-bacterial medium would be expected to have accelerated copper extraction because of the conversion of any sulfur product layer on the chalcopyrite anode to sulfuric acid according to the following general reactions: [MS?M2+ + S° + 2e- (1) and 2S° + 302 + 2H20 bacteria?-2H2SO 4 (2)] where M in reaction (1) designates the metal (or metals in the specific case of chalcopyrite) to be released to solution by galvanic conversion.

Jan 1, 1982

By M. H. Kline

Round Mountain is one of a number of locations investigated by the Bureau of Mines in its search for manganese deposits during the early phases at the strategic minerals program. The Suiter mine, on Round Mountain, had provided some 5,000 tons of manganese concentrates during the period 1917 to 1919, and early in 1941 prospecting by the Virginia Hardwood Lumber Co. in this same area had discovered manganese on what later became known as the Hall Pit. These promising indications encouraged the Bureau to begin an exploration project in search of additional reserves of manganese on Round Mountain in January 1942 (fig. 1).

Jan 1, 1948

By X. H. Li, Q. Zhang, X. Fei

Bauxite residue known as red mud (RM) is a by-product produced in massive quantities during alumina production by the Bayer process with a utilisation rate of less than 5%. A large amount of RM accumulated and produced continuously has had a seriously adverse impact on the surrounding ecological environment. The application of RM in building materials is considered to be the most effective and thorough way to make RM harmless and recycle resources for the reason that adding RM to concrete as a mineral admixture could not only consume a lot of RM, but also save cement and other energy-consuming industrial products. In this paper, the adaptability to cement and aggregate of RM was studied. The results showed that the compressive strength and flexural strength of concrete using ordinary Portland cement, slag Portland cement or fly ash Portland cement as cementing material showed different trends with the increase of the amount of RM. The influence rules of RM on the compressive strength of Portland cement, slag Portland cement and fly ash Portland cement concrete were similar, whether for silicate aggregate or carbonate aggregate. RM has a negative correlation to the flexural strength of silicate aggregate-ordinary Portland cement concrete, but a positive correlation to silicate aggregate-slag Portland cement, silicate aggregate-fly ash Portland Cement. RM promoted the formation of calcium carbonate crystals and inhibited the formation of ettringite and calcium hydroxide crystals in the matrix while ordinary Portland cement, Portland cement and fly ash Portland cement were used as cementing materials. This study provided support for the use of RM in concrete, the reduction of solid waste storage, and the saving of high energy consumption cement as well. Keywords: Red mud, cement, aggregate, adaptability, mechanical properties, mineral composition

Jan 1, 2020

By R. H. Snow

Although industrial size reduction methods have an energy efficiency of only about 1 percent, methods of size reduction have not changed much for many years. One reason for slow progress has been the oversimple viewpoint that a single law should exist to relate size reduction to energy input. Modern simulation methods decompose the grinding process into a grinding rate function (selection function) and a breakage function. The breakage function is difficult to measure, and it usually requires tracers if it is determined from milling experiments. Prediction of breakage functions from basic principles is one objective of this paper. In this study we focus attention not on the gross energy input to the experiment, but on the spatial distribution of stress energy within the particle. We are led to this viewpoint by experimental observations of a few previous investigators (Bergstrom2, Rumpf3, Axelson4) and our own observations. Oka and Hiramatsu recently used their calculations of stress within particles for prediction of breakage, but again they tried to correlate the size of the fragments with the total stress energy, rather than the approach we propose. We assume that the stress energy is stored in the interior of the particle as the load is increased, until the particle breaks. We assume that each element of the particle breaks into fragments of a mean size that depends on the locally-stored stress energy. The size distribution of fragments is the computed from maps of the stress-

Jan 1, 1972

By W. A. Wilkinson

Mining companies today are under increasing pressure to boost output from their existing mines and to bring new projects online quickly. Fundamental to the long-term performance of an operation is geologic modeling and mine planning. To maximize mine profitability, planners and schedulers must account for a staggering array of variables and create accurate mining plans that meet production and profit targets. Not surprisingly, this can be a difficult task, and getting it wrong can result in large unforeseen costs and significant lost revenue opportunities. This paper discusses the top five challenges geologists and engineers are facing in developing mining plans.

Jan 1, 2012

By Jerry Wallace

Construction of a new grammar school required blasting within three meters of the existing school. Due to changes not anticipated at time of bid opening, blasting had to take place while approximately 200 children were in attendance inside the building. Blasting with children in such close proximity forced the blaster to review and revise a systematic approach to construction blasting and make changes to previous Rules of Thumb guidelines. The revised rules of thumb place Blaster-in-Charge at the top of the List. Other changes specific to the project included putting in place a blasting safety plan that included communicating the serious job hazards to teachers and students. The plan included stringent lockdown guidelines establishing school procedures for accounting for each student prior to the countdown-to-blast being implemented. Emergency communications channels were kept open so that any scheduled blast could be aborted at the last instance.

Jan 1, 2001