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By H. X. Li, A. Correa, M. M. Zhang, W. Xuan, M. Andrade

"With increasing demand for steel and depletion of high-grade iron ore deposits, more research efforts are being directed toward extending the life of existing ore reserves and developing technology to treat low-grade iron ore resources. Among all the reported technologies, biotechnologies in mineral processing – specifically bioleaching and microbially induced flotation – have emerged to be considered as low-cost, environmentally friendly potential alternatives to many of the current mineral processing techniques. This paper provides a comprehensive review of current research on the use of microorganisms for iron ore beneficiation and, further, discusses the applicability of bioleaching, bioflotation and bioflocculation for the beneficiation of low-grade iron ores.IntroductionIncreasing global demand for raw materials has led to diminishing resources of high-grade iron ore. As a result, the mining and utilization of low-grade hematite, limonite, specularite, siderite and goethite ores have attracted more and more attention. However, these types of iron ores are of complex paragenesis and fine disseminated grain size, and often contaminated by phosphorus in the form of solid solution. The distribution of phosphorus throughout the iron mineral crystals prevents the effective use of physical separation techniques, and these complex ores are at present largely untapped due to a lack of cost-effective and efficient processing methods. Chemical leaching and roasting-magnetic separation approaches have been mainly tested only on the laboratory scale and are all either cost prohibitive or ineffective when used on low-grade complex iron ores."

Jan 1, 2015

By Xiyu Gao, Yi Yang, Mark I. Pownceby, Shuiping Zhong, Miao Chen

In the present study, X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray absorption near edge structure (XANES) spectroscopy, and Raman spectroscopy were used to investigate the effect of chloride ions on chalcopyrite bioleaching and chemical leaching at 25 °C. The leaching results show that the addition of chloride ions suppressed the dissolution of chalcopyrite in both chemical and bacterial leaching. In chemical leaching, the solution redox potential in the experiment without Cl− stayed in a range more suitable for chalcopyrite dissolution compared with experiments with Cl− . In bioleaching, the bacteria activity was suppressed by Cl− leading to low dissolution rates of Cu. Surface morphology and chemical speciation studies confirmed the formation of potassium jarosite on the surface of the chalcopyrite leach residues. In addition, S K-edge XANES indicated the formation of trace amount of elemental sulfur and covellite on the mineral surfaces.

By J. K. Ahlness

The Bureau of Mines investigated technologies for determining the integrity of in situ leach mining wells. A self-contained trailer-mounted well integrity testing system (WITS) was designed and built to enable rapid testing of well casings for leaks as required by environmental regulations. The WITS utilizes two inflatable packers to seal off the entire casing length or any portion thereof. Water pressure is built between the packers to the desired test pressure, and the presence or absence of casing leaks is determined by monitoring the pressure drop between the packers. A winch and steel cable are used to run the packers in and out of the well. The WITS underwent an industry field test at the Irigaray in situ uranium leaching mine near Buffalo, WY. A total of 37 wells with an average depth of 225 ft (69 m) were tested at an average rate of four wells per 8-h shift with a two-person operating crew. This represents a 75-pct time savings and an 83-pct labor savings compared to the rigid-pipe method previously used at the mine, with which a three-person crew tested an average of one well per shift.

Jan 1, 1986

By J. Drelich

The flotation limit of fine particles has been re-examined based on the effect of bubble size on contact angle, and a new surface chemistry-limited relationship describing the minimum particle size which can be floated is proposed. In this analysis the critical value of bubble-solid contact radius (re) for which there is no effective attachment between particle and bubble has to be determined. The values of re determined by extrapolation of our experimental data for contact angle versus bubble-solid contact diameter permit the prediction of the flotation limit of methylated quartz particles, with fraction-al coverage of trimethylsilyl groups from 0.07 to 0.51. The limit of fine particle flotation as determined by this theoretical approach agrees well with experimental data reported in the literature.

Jan 1, 1994

By T. K. Bundtzen, C. B. Green

Exploration expenditures in Alaska last year amounted to $8.9 million. This was comparable to 1985's $9.1 million. Development expenditures dropped 29%, $24.3 million in 1986 vs. $34.1 million in 1985. The exploration industry is restructuring and stabilizing after the loss of major mineral firms during the last few years. These included Anaconda Minerals, Asarco, Hecla Mining, Enserch Exploration, Phillips Minerals Division, Exxon Minerals, Noranda Inc., General Crude, Mohawk Oil & Gas, Inspiration Development, Teton Exploration, and St. Joe Minerals Division. Some of these companies were mineral subsidiaries of oil companies and were either dissolved or redirected to programs outside of Alaska. However, recent entry exploration firms include Echo Bay Mines Ltd., Long Lac Minerals, and Exvenco. They are busy evaluating prospects and mineral developments in the southeastern panhandle. In the 1970s, about $254 million was spent on Alaska mineral exploration. Of this, about 5% ($12 million) was for nonmetallics and coal, about 26% was directed at precious metals ($66 million) mainly gold, and 69% ($175.3 million) for the base metals zinc, copper, molybdenum, tin, tungsten, and nickel. Since the early 1980s, trends have reversed. Of the nearly $196.3 million spent from 1981-1986, 48% has been for precious metals ($94.3 million) and 40% on nonmetallics and coal. In the last two years, nearly 70% of the Alaskan exploration dollar has been spent in search of precious metals. Three gold skarns were explored during the year - the Nixon Fork project in western Alaska (Battle Mountain Mining Co.), the Nebesna and Rambler lodes of the northern Wrangell Mountains (Nebesna Mining Partners), and the Zackley project near Paxson in southcentral Alaska (Nerco Minerals). Nearly 7.6 km (25,000 ft) of diamond and rotary drilling were conducted on these three properties. Aspen Exploration announced that significant gold mineralization was found under the Nome coastal plain in western Alaska. Meridian Minerals joint ventured with Resource Associates of Alaska, exploring precious metal

Jan 5, 1987

By Kenneth F. Wyman

The following report details the successful construction of Contract 2A of the Three Rivers Water Quality Management Program, Intrenchment Creek Combined Sewer Overflow Conveyance System, in DeKalb County for the City of Atlanta, Georgia. The contract required construction of approximately 2878 m (9443 ft) of tunnel bored to an initial diameter of 7.95 m (26 ft 1 in), with provisions to concrete line those portions designated by the engineer to a finished internal diameter of 6.91 m (22 ft 8 in). Flanking the tunnel are two shafts. The upstream shaft was excavated to a nominal diameter of 4.87 m (16 ft) to accommodate a finished internal diameter of 3.66 m (12 ft). This shaft required a transition boot fully concrete lined to final dimensions of 6.91 m (22 ft 8 in) wide, 13.72 m (45 ft) long, and varying in height from 6.91 m (22 ft 8 in) to 12.80 m (42 ft). Associated work necessary to complete the contractual obligations included installation of 22.86 m (75 ft) of cut-and-cover box culvert, 484 m (1589 ft) of open-cut sewer installation in sizes ranging from 0.30 m (12 in) to 1.68 m (5 ft 6 in), one river crossing, 137.46 m (451 ft) of monolithic concrete trapezoidal channel, and installation of 19125 cu m (25000 cu yd) of select fill material compacted and graded to finished contours. The downstream shaft was excavated to a minimum diameter of 12.04 m (39 ft 6 in) and concrete lined to a finished internal diameter of 10.67 m (35 ft). Requirements here included installation of a complete pumping station with all mechanical, electrical, and structural elements necessary for dewatering the tunnel through the controlled use of four 250 hp submersible pumps discharging into the facilities of the Intrenchment Creek Water Pollution Plant. The objective of this project was to collect combined storm runoff and sanitary flows currently coursing through Intrenchment Creek

Jan 1, 1985

By J. O. Marsden

This paper presents an overview of the innovative methods for gold and silver extraction that have been put into actual practice in North America since 1987. It is an update of a paper of the same title which was presented by Sass and Mansanti at the AMC conference in San Francisco in 1987. New practices, new equipment and variations of older practices that have been introduced in the last five years are discussed in each of the following categories: process selection trends, comminution, gravity concentration, flotation, oxidation, agitated and vat leaching, heap leaching, solution concentration and purification, zinc precipitation, electrowinning, tailings disposal detoxification, and reclamation.

Jan 1, 1993

By Reece Kurre, Gabriel Walton

"Roof bolting has long been used in underground mines across the world to provide ground support. Modern roof bolts are cheap and easy to install with the use of specialized machines as a part of the production cycle. Lhoist North America’s Crab Orchard Mine is an underground room and pillar limestone mine that uses mechanically anchored roof bolts for ground support. The mine currently employs two different roof bolting patterns: a standard 5 × 5 foot pattern, and a 2.5 × 2.5 foot pattern for use in areas with particularly hazardous roof conditions. The purpose of this study is to evaluate the relative effectiveness of each bolting pattern.A series of numerical models were created using RocScience’s RS2. The models were based on a symmetrical section of the mine at its deepest point, and were modeled using Generalized Hoek-Brown failure criterion along with a discrete fracture network. A series of sensitivity analyses were performed on the models by varying parameters such as joint friction angle, crack persistence, joint randomization, and tensile strength of the limestone. Based on the results of the original models and sensitivity analyses, it appears that the standard bolting pattern provides sufficient roof support capacity under almost all the expected conditions at the mine, since factors of safety below the design value of 1.5 were only found for individual bolts in a few of the worst test cases considered. These results can help improve the Mine’s productivity and reduce operating costs without compromising safety.INTRODUCTION AND CASE STUDY DESCRIPTIONLhoist North America’s Crab Orchard Mine is an underground limestone mine located in Crab Orchard, Tennessee. The mine is located under an 800-foot-high mountain, and outcrops on three sides. The mine is accessed through three separate portals and has two main levels, along with a partially developed third level. Extraction is accomplished by the room and pillar method using 50 × 50 feet pillars and 50 × 50 feet rooms. The mining height is limited to 50 feet to keep the pillar width to height ratio around 1.0. Each heading is excavated in a two-stage process that consists of a 30-foot-tall top heading and a 20-foot-tall bench. A distance of at least 30 feet is maintained between the two levels at all times (Crab Orchard Mine Technical Staff, 2017)."

Jan 1, 2019

By Paul H. Johnson

Resource Engineering and Development, Inc. is designing and building a portable 150 to 225 TPD, flotation-cyanide leach plant with unitized, skid-mounted components. This plant design, with its portability, low capital investment, and high recovery of silver and gold from many partially oxidized ores, is well suited to treat many small, high-grade deposits, old waste dumps, and old mill tailing piles. A description is given of flotation and/or cyanide leach tests run on about 17 partially oxidized, newly mined ores; waste dump materials; placer slimes; and old mill tailings.

Jan 1, 1981

By Marcos de Paiva Bueno, Leonardo Ribeiro Lara, Rajiv Chandramohan, Thiago de Almeida, Greg Lane

This paper explores the impact of the significant difference between the number of geochemical assays conducted for grade estimation and the number of comminution tests performed for throughput and performance forecasting. Both grade and throughput are key factors in determining the project. We analysed 154 feasibility study reports to assess the impact of sample frequency for comminution test work on project revenue. This disparity in size between assay and comminution data arises because geological and resource-grade risks cannot be managed without extensive geochemical testing, whereas comminution risks are traditionally mitigated through design methods and the use of contingencies. This approach is partly due to the relatively high cost and large sample requirements associated with traditional comminution tests. Our analysis demonstrates that insufficient comminution sampling and testing leads to uncertainties in throughput forecasts, creating significant financial risks. Data from the feasibility studies show that a 1% change in mill throughput can result in up to a 5% variation in Net Present Value (NPV), underscoring the sensitivity of project economics to operational performance. Building on previous work, we reference studies that reveal how low frequency of comminution testing can increase uncertainty in mill throughput forecasts and increase financial risks. We propose an approach that optimises the number of comminution samples tested to enhance forecast accuracy and reduce NPV variance. By adopting this approach, mining projects can improve financial reliability and mitigate risks associated with underperformance in SAG and AG mill-based operations.

Feb 1, 2025

By J. L. Yordan

An induction time apparatus has been constructed in the present work which has a sensitivity limit of 100-150 micro-seconds. The basic unit is similar to the one used by Eigeles and Volova (1960) and Trahar (1983), but it operates with a micro-computer and has a greater sensitivity. Using this apparatus, the flotation chemistry of the quartz-amine system has been studied. It has been found that at a given dodecylamminium hydrochloride concentration, the induction time is at a minimum at approximately pH 10.5. At this pH, the collector hydrolizes to form neutral amine and the flotation recovery reaches a maximumy,suggesting that iono-molecular species are the surface-active species responsible for flotation. This finding confirms the earlier conclusions obtained using the surface tension (Somasundaran, 1976; Finch and Smith, 1973) and contact angle (Smith, 1963) techniques. The induction time measurements have also been conducted as a function of particle size, collector concentration, indifferent electrolyte concentration and temperature. The results are compared with flotation data, and the activation energies for the bubble-particle adhesion have been calculated.

Jan 1, 1986

By H. R. Manouchehri

"Pyrrhotite (Po) is one of the most abundant sulfide minerals in processing industry and must be rejected in most cases. Particularly, Po rejection and its selectivity against pentlandite (Pn) have long been a challenge due to similarities in the mineral composition of the two minerals and the collectorless flotation characteristics of Po. Xanthates have been widely used to promote sulfide mineral flotation; however, in the presence of xanthates, the redox potential established at the mineral/solution interface is most important, determining the flotation performance. In this paper, the importance of electrochemistry in Po and Pn flotation has been demonstrated and a comprehensive study was conducted on two different feed streams (i.e., magnetic concentrate and scavenger cleaner streams, containing magnetic and nonmagnetic forms of Po, respectively), from Vale’s Clarabelle Mill in Sudbury, Ontario, with an objective to determine if improvements in Po rejection and Pn recovery could be achieved by controlling pulp electrochemistry. By conducting a series of flotation tests under different Eh conditions and reagent usage schemes, it was revealed that higher Po content in the magnetic stream may protect Pn from being oxidized, improving Pn recovery. The results indicated that at low oxidizing pulp chemistry, the rest potential for the Pn is still high enough to allow the formation of dixanthogen to promote its flotation. Using a Pt electrode, it was found that by controlling pulp potential at -50<Eh< +50 mV, the Pn recovery and Po depression would be satisfactory. The results, using mineral electrodes (Outotec Chena analyzer), indicated that selective separation can be achieved if low-to-moderate oxidation potentials (0 to 100 mV) or reduction (0 to -100 mV) potentials are monitored using Pn and Po electrodes. Mixing two streams at 50:50 wt % would be possibly beneficial in selective separation.IntroductionPyrrhotite (Po), Fe1-xS, is one of the most abundant sulfide minerals in the processing industry. It is an iron-deficient sulfide that occurs either in monoclinic or hexagonal form. The monoclinic one is richer in sulfur and is ferromagnetic, whereas the hexagonal Po is poorer in sulfur and has no magnetic properties. In general, the ferromagnetic properties of natural Po increase with increasing sulfur content. Although Po holds significant iron content, it is not used as a feedstock for the iron and steel industry due to the difficulty in achieving complete removal of sulfur. The common availability of iron oxide ores makes the iron sulfides irrelevant for the steel industry."

Jan 1, 2015

By J. Drelich

An improved experimental procedure to measure contact angle has been consolidated with coal surface preparation involving polishing with abrasive paper, alumina powder, and a cloth, followed by ultrasonic and mechanical cleaning. Specifically, the captive-bubble measuring technique has been compared with the sessile-drop technique and the former has been recommended for the examination of the hydrophobic properties of coal surfaces. Results of the research program, which is currently under way, on the examination of the effect of the nature, amount, size and distribution of mineral inclusions in coal on its wettability are briefly reviewed.

Jan 1, 1999

By Giovanni Barla

This paper examines the application of gelatin mixture models to the study of factors such as gravity effects, tectonic and residual stresses, anisotropy, physical nonlinearity, time-dependent behavior of the rock mass and connectedness of the geologic space. The calibration technique of gelatin mixtures, proposed by Richards and Mark in 1966, is applied to the particular problem considered. Similitude relationships between model and prototype are discussed with reference to the constitutive equations describing the physical behavior of the rock mass. The interaction between two openings in a linearly elastic medium, under conditions of plane strain, is used as an illustrative example, with the view of describing the history of stress and deformation changes on the rock medium and lining around a slusher drift while undercuts are made in block caving.

Jan 1, 1968

By John C. Harkey

The paper shares programs that presently use the CDC PLATO System to train individuals in industry. A short history of PLATO development; as a training system is presented with reflection on the major training trends being used to improve training effectiveness. A discussion is offered to describe the benefits of using a system for individualizing instruction. An introduction; is offered showing how one can recognize&apos; individual differences, with an explanation of how the strengths of a computer are used to deliver and manage the training. Simulations of hazardous processes are shown to be one of the most effective uses of the computer for training.

Jan 1, 1979

By J. Kemeny, J. Lyons-Baral

"Point cloud technology is now an indispensable tool in geological and geotechnical data collection, interpretation and analysis. Open-pit and underground mines of all sizes are regularly collecting point cloud data as laser scanning (LiDAR) and photogrammetry surveying devices have become affordable and the workflows fast and efficient. Past challenges of large data processing and manipulation are gone with recent technological advancements in computer hardware and software. These innovations reduce file sizes, ease rendering requirements and allow for the implementation of real-time 3D viewers and surface meshing tools. With its ability to remotely and safely, rapidly and accurately extract large quantities of georeferenced and 3D-oriented data, point cloud technology provides numerous applications to the geomechanical field. The list of uses is continuously growing. This article specifically focuses on digital outcrop modeling and digital terrain engineering. Point clouds. The high-resolution and increasing availability of point cloud technology is rapidly improving open-pit and underground mines’ investigation, interpretation and characterization of site geology and rock mass properties (Kemeny et al., 2015; Lyons-Baral, 2012). LiDAR and photogrammetry are common remote sensing methods employed to measure the coordinates of surfaces in three dimensions (3D), providing the X, Y and Z locations and typically the reflective intensity and/or the visible three-band color of each point (Fig. 1).LiDAR uses either a time-of-flight or phase-shift measurement of a laser beam reflected off targeted surfaces and received back into the device.Photogrammetry generates point clouds by merging multiple overlapping photographs and uses stereographic plotting to define the locations of object points in 3D space. These methods can be deployed from airplanes, unpiloted aerial systems (UAS or drones), tripods, land vehicles and even in a mobile backpack shown in Fig. 2. RADAR, Total Station-Prism and other remote sensing systems also offer very precise “point clouds,” but this article does not address these due to their higher cost and lower versatility and mobility."

May 1, 2016

By A. C. Bigley

Before going into this subject, I would very much like to call to your attention some past history on patents granted by the United States Patent office that involved ammonium nitrate. On February 10, 1885, a patent was granted to Russell S. Penniman. "The object of this invention is to securely protect ammonium nitrate against deliquescent and to maintain it in substantially its normal disintegrated condition, so as to afford a new product suited for ready use in the manufacture of high explosives, and enable the immediate admixture thereof with any of the well known explosive substances or compounds heretofore employed. &apos;Whether the nitrate be thus granulated or otherwise reduced to a granular or divided condition, it is then thoroughly mixed with about twelve (12) percent of the fluid or semi-fluid carbonaceous protecting medium, which forms a readily applied jacket or coating for the granules of nitrate and also serves as a carbonaceous element in such explosive compounds as it may thereafter be employed in."

Jan 1, 1958

By K. V. Raj, C. A. Berry, A. T. Weakley, A. L. Miller, P. R. Griffiths, D. A. Parks

Diesel particulate matter (DPM) has been classified as a carcinogen to humans by the International Agency for Research on Cancer. As a result of its potential carcinogenic nature, DPM exposure is regulated by the Mine Safety and Health Administration. Currently, diesel emissions in the workplace are monitored by collecting the aerosol onto filters, which are then sent to a laboratory for thermal-optical analysis using the NIOSH method 5040. This process can take days or even weeks, and workers can potentially be exposed to excessive levels of DPM before the problem is identified. Moreover, the delay involved in getting the loaded filter to the lab inevitably means the loss of some of the more volatile organic carbon. To remedy this delay, researchers from the National Institute for Occupational Safety and Health are seeking to develop a field-portable, real-time method for measuring elemental and organic carbons in DPM aerosols. In the current study, the use of mid-infrared spectrometry was investigated. It is believed that mid-infrared spectroscopy is more suitable for use in a real-time field-portable device than thermo-optical analysis methods. This article presents a method for measuring organic carbon (OC) and elemental carbon (EC) in DPM for a broad range of OC/EC ratios. The method has been successfully applied to laboratory-generated and mine samples.

By T. Kawashima

The expanding volume of maritime coal transportation is intensifying the problems concerning large vessel service port construction, transshipment and environmental control. The major problem is the transshipment of coal. Customary methods for bulk transfer must be improved and/or new systems developed. Slurry unloading has a key role in the new systems. The present report reviews progress in slurry transportation research which has been done in Japan since the 1960s when large scale experiments for domestic transportation were done. Experiments on the effects of vibration on the slurry cargo and on reslurrying are discussed.

Jan 1, 1982

By Marvin P. Barnes

An attempt has been made to compile and code geologic data relating to twenty of the major porphyry copper districts of North America in such a manner as to permit the use of modern electronic digital computers to retrieve, compare, and build statistical mathematical models from the input. In the exploration process as part of his broader efforts to evaluate the potential of some prospective region, district, or ore body, the experienced geologist consciously or subconsciously compares and fits the observed geologic features to similar phenomena associated with known ore bodies with which he is acquainted. Thus an adequate conceptual "model" of the total geologic environment and type of ore body sought is an essential requirement for the successful exploration effort. Numerous such models of porphyry coppers already exist in the minds and notes of many experienced geologists today. These models are, of necessity, couched largely in qualitative terms and though they may be quite definite in the mind of the porphyry copper expert, the total concept of what constitutes a porphyry copper deposit and environment is difficult to convey in very precise terms. There probably is no such thing as a typical porphyry copper deposit. However, it is well understood that most of the deposits that have been studied have many geological characteristics in common. A logical question then might be: What characteristics are most common or how often do they occur in common, and what is their relationship to other common characteristics ?

Jan 1, 1970