Search Documents

By Malcolm Black

Introduction The circumstances under which the gold mining industry was forced to curtail operations a few years ago are well known to all. The effect of those circumstances is particularly noticeable when one enters some of the larger mills that were designed, in better times, to treat relatively large tonnages. On their grinding floors one will observe that a number of grinding units are lying idle, and the ravages of rust are everywhere in evidence. The same applies to other equipment throughout these mills. In 1941, we found it necessary to reduce tonnage considerably in the Wright-Hargreaves mill. With the assumption that a lower tonnage would be of long duration, we began to focus our attention on some of the idle equipment with a view to re-arrangement of the flow-sheet for greater economy of operation. In an article by the writer published in the Engineering and Mining Journal (March, April, and May issues, 1939) , it was pointed out that in designing this mill there was a very limited floor space available. The choice of thickening equipment was imposed solely by the necessity for space: conservation. Thickening by gravity would have required 5,000 square feet of floor space, whereas Genter thickeners required only 1,200 square feet. As a consequence, the Genters were chosen. The decision to add flotation to the circuit was made primarily to save space. On a cost-plus-tail basis, 80 to 100 hours agitation on all pulp would produce similar overall results, but would require much more space.

Jan 1, 1948

By A. Block-Bolten

Copper concentrates from northern Peru contain large amounts of arsenic and antimony in the form of sulfosalts like enargite, tennantite and tetrahedrite. These impurities affect up to 30% of Peruvian copper production. Under the sponsorship of the Instituto Geologico Minero y Metalurgico in Lima a project to separate copper from arsenic without pollution of the environment is being carried out at the National University of Trujillo in Peru. The U.N.T. process is unique in the respect of using .low melting salts as solvents, and sulfides of metals with high cation potential as destructors of the complex sulfosalt molecules. Laboratory scale experiments have given encouraging results but interesting and difficult problems developed on scale-up. The process is pyro-hydrometal-lurgical and under certain circumstances its economics are promising.

Jan 1, 1981

By Hugh Roberts

During 1916 and 1917, the E. J. Longyear Co. of Minneapolis, Minn., carried out a campaign of exploration for nickel-copper ore in the Sudbury District of Ontario. The work was initiated by W. E. Smith, a resident of Sudbury, who called the attention of W. J. Mead, Chief geologist. The E. J. Longyear Co., to the fact that explorable lands in the Sudbury District were still available. Five diamond drills were employed, and holes were drilled in the townships of Levack, Trill, Denison, Blezard; Garson, Falconbridge and MacLennan. The general map of the District, Fig. 1, shows the distribution of the lands chosen. As a result of this exploration, a large body of nickel and copper ore has been found in the western part of the Township of Falconbridge. This property lies in the eastern part of the Sudbury District, east of the Garson mine.

Jan 2, 1918

By Santiago Garcia, Dariusz Lelinski, Devan Govender, Tyson Baker, Mads Jespersen

"In recent years, the scale-up of mechanical flotation machines has been attempted with greater frequency. In contrast, the development of rotor-stator designs has been subject to greater inertia. The rotor-stator components are integral to the operation of mechanical flotation machines, responsible for the key physical processes of solids suspension, gas dispersion and energy dissipation. Design modifications are predicated upon the dual purpose of meeting customer needs while achieving metallurgical performance objectives. Accomplishing the latter is a rigorous undertaking, typically involving the sequential application of fluid dynamics principles, prototyping, smaller-scale research screening studies and larger-scale development projects. This industrial evaluation details the final stages of the forced-air rotor-stator development process using a double-refractory Carlin-type gold ore. A bypass stream of the primary rougher feed was further classified into cyclone underflow and overflow products. Four rotor-stator treatments were evaluated using parallel flotation rows coupled with a randomized statistical design. Only two treatments are compared in this initial assessment. Metallurgical responses were measured as a function of the random variation of key machine factors. Machine characterization measurements complemented the analysis of flotation performance indicators."

Jan 1, 2014

By Chris Twigge-Molecey

Demand for metals will continue to grow as global population numbers and prosperity levels steadily increase. Consequently, there will continue to be a need to design and construct new metallurgical plants. Business success in general requires projects to be financially successful and return appropriate value to their owners. However, in the metals industry, private and public sector financing sources have become very sensitive to the perceived inability of projects to contain costs and meet other business objectives. Thus, the capital for projects has become more difficult and expensive to obtain. It is instructive to note that Ernst and Young (2011) identified that: “Delivery of predictable project results bestows competitive advantage and market confidence to those corporations who successfully instill this discipline”. The implication for future projects is that they must be systematically developed to minimize perceived risks—and more importantly—to demonstrate that the risks are managed to achieve the business case. Then, provided that the project has been developed in a well-structured way, project success can again be defined as a project with: a final cost within 10% of the budget approved at the end of FEL3, when the project is properly defined and the permit conditions are agreed upon; a start-up date within three months of the definitive, scheduled startup date; production levels at 85% of design capacity within a year of starting commercial operation; production meeting the target environmental restrictions; and with zero lost time accidents during construction and startup. The plant design is one of many integrated activities required to achieve these objectives. This book represents a valuable link between the existing engineering literature that encompasses a wide range of engineering fundamental textbooks and design manuals and the project management literature such as the Project Management Body of Knowledge, or PMBOK® (Project Management Institute, 2014). It is evident throughout this book, that the design team is a small but essential part of a much larger project team comprising the project management, construction management, and construction contractor staff. Design activities must be regarded and managed as part of the integrated whole, with two fundamental links throughout the design process:

Jan 1, 2015

By Laurence Pellier

Electron microscopical studies were made of the effect of sensitization at 1200oF on a Type-.104 stainless steel with high carbon and low nitrogen and oxygen contents, after solution annealing and after cold working. The loci of the carbide precipitates in the early stages of sensitization were followed in dry stripped plastic replicas. Some observations were made by direct electron transmission on thinned films. Intragranular dislocations showed a high degree of stability through the annealing necessary to produce sensitization. I HE present work was undertaken to determine the effect of sensitization, at 1200°F, for 1/2 hr, on the electron microstructure of a Type-304 stainless steel with high carbon, and low nitrogen and oxygen contents, after solution annealing and after cold working. Many electron microscopical studies of sensitization of 18-8 stainless steels have already been made. Most of them utilized extraction replicas, from which the morphology and composition of the precipitated carbides could be established.'-" ry stripped replicas were seldom used for such studies, although it was demonstrated that they are applicable, in general, to EurveYs of the general microstructure of many alloys' and, in particular, to the observation of precipitated carbides in austenitic stainless steels.3

Jan 1, 1963

By J. C. Judd

The U.S. Department of the Interior, Bureau of Mines investigated solvent extraction methods for recovering gallium from filtrates produced from sulfuric acid leaching of hydrometallurgical zinc residues. These filtrates typically had pH values of 0 to 0.5, too high an acid content for effective gallium recovery by traditional extractants. Of the nine extractants studied in batch tests, 0.3M octyl phenyl acid phosphate (OPAP) in a kerosene diluent was the most effective extractant for gallium recovery, extracting up to 99.9 pct of the gallium. This high extraction was possible when the iron in solution was maintained in the reduced ferrous state. Batch tests also showed that a 1.5M-H2SO4 strip liquor recovered 98 pct of the gallium from the loaded OPAP. A continuous solvent extraction system was designed and operated based on McCabe-Thiele analyses of equilibrium loading and stripping isotherms. When 12 L of leach filtrate containing 0.32 giL Ga and 20 giL Fe were pumped through the system in 32 hr, results showed that 95 pct of the gallium was extracted in four stages at an A:O ratio of 1:1. Stripping the loaded solvent with a 1.5M-H2S04 liquor recovered 94 pct of the gallium in four stages at an A:O ratio of 1:4. A two-stage, 50-pct-phosphoric acid strip successfully removed ferric iron from the OPAP, allowing high gallium extractions to be maintained.

Jan 1, 1990

By T. Gupta, T. Ghosh

"Rare Earth Elements (REEs) and their compounds are essential for numerous modern high tech applications such as renewable energy technologies, catalysts and defense applications. The destabilization of REE pricing owing to the global demand and supply deficit has forced many countries to re-evaluate the possibility of indigenous production of REEs. Cost effective and eco-friendly opportunities are being widely explored for extraction of REEs from non-conventional mineral sources such as coal and coal byproducts to stabilize the supply chain. Coal from Central Alaska (Healy Coal Mine) and Southern Alaska-Cook Inlet (Wishbone Hill) province have been found to possess elevated REE concentrations as compared to average world coal estimates. The objective of the study is to enrich the REEs in the fine size fraction (-75 Microns) from Healy and Wishbone Hill by froth flotation technique. A Box-Behnken design was applied for modeling and optimization of some operating variables on the flotation to maximize REE enrichment. The variables studies were frother dosage, pulp density (% Solids) and collector dosage. Experiments were carried out using a statistical design and the main and interaction effects on response variable was evaluated by analyzing 3D response surfaces. Based on the experimental results the optimum flotation conditions for maximum REE enrichment in the froth fraction was obtained at 4.2% Solids and 32.7 ppm of frother dosage for Healy coal sample and 10% Solids and 37.9 ppm of frother dosage for Wishbone Hill coal sample. The quadratic equation for modelling and optimizing the response variable is found to be independent of collector dosage for both the coal samples. INTRODUCTION Alaskan coal deposits are distributed in three major coal provinces and are in Cretaceous and Tertiary rocks. The climate, vegetation type and sedimentation process has attributed to low sulfur content (averaging 0.3 percent) in Alaskan coals compared to other coal deposits found across the globe. In Central Alaska-Nenana and Southern Alaska-Cook Inlet coal province coal resources are contained in Tertiary rocks while bulk of the Coal resource in North Slope coal province is contained in Cretaceous and Tertiary coal bearing rocks [1]. Coals from Central Alaska- Nenana (Healy) and Southern Alaska-Cook Inlet province (Wishbone Hill) have been found to possess elevated concentrations of critical REEs as compared to the amounts present in world coals (Figure 1). The Wishbone Hill deposit is considered a relatively small deposit, with about 14 million tons of identified reserves, compared to Healy which has over 500 million tons identified [2]. The REE concentrations up to 286 ppm and 524 ppm on ash basis have been reported by Gupta et al. in 2016 with elevated concentrations Ce, La, Y and Nd which are expressed to be of critical importance by US Department of Energy. Accordingly, the two coal samples possess the potential to be used as a REE resource in the near future under favorable socio-economic and geo-political scenarios. [3, 4]"

Jan 1, 2017

By G. Popplewel

Commencing with the Pre-Feasibility Study (PFS) conclusions, the Orapa 3 process design evolved through a phase of value-engineering studies. An overall re-evaluation of the originally proposed process design was necessary both in order to address the interim increase in target throughput from 9.8 Mtpa to 12 Mtpa as well as to increase capital efficiency. In the interests of clarity, the PFS process design for Orapa 3 has been omitted from this paper, as it is no longer relevant. Recognition is however due to those engaged in earlier phases of the Orapa 3 project with respect to fundamental mass-balancing modelling; and ore and diamond characterization, which fanned the basis for the process design that has evolved from feasibility study activities.

Jan 1, 2010

By A. J. Kraemer

[The Bureau of Minas for a number of years has been studying the properties of crude petroleum from producing fields in the United States and Western Hemisphere and has published a series of reports on these fields, including oil fields of Texas.5]

Jan 1, 1927

A virtual reality approach is presented that can aid entities such as mining companies and land use planners in communicating a visual understanding of a mining operation to interested stakeholders, citizens? groups, and public committees. These visualizations are particularly useful in permitting, production planning and mining closures, contributing to accurate communication and evaluation of mine plans, ultimate land use and evaluation of potential design options A case study is presented, that was created using commercially available virtual reality tools, to emphasize the benefits of visualization technologies in the sustainable development of mineral resources.

Jan 1, 2003

By M. Balamurali, K. M. Seiler

Modelling stockpiles is a key factor of a project’s economics and operation in mining, because not all the mined ores are not able to mill for many reasons. Furthermore, the financial value of the ore in the stockpile needs to be reflected on the balance sheet. Therefore, automatically tracking the boundaries of the stockpile facilitates the mine scheduling engineers to calculate the tonnage of the ore remaining in the stockpile. This paper suggests how the dynamic of stockpile shape changes caused by dumping and reclaiming operations can be inferred using polygon models. The paper also demonstrates how the geometry of stockpiles can be inferred in the absence of reclaimed bucket information, in which case the reclaim polygons are established using the digger’s global positioning system (GPS) positional data at the time of truck loading. This work further compares two polygon models for creating 2D shapes.

Sep 1, 2021

By J. D. Miller

The sedimentary western phosphate deposits of Idaho, Montana, Utah, and Wyoming tend to be calcareous and generally carry a significant amount of dolomite along with collophanite. In some cases, such as the Smokey Canyon Mine, Afton, Wyoming, the ore will also contain mudstone, and in this case the aluminosilicate minerals (clay, feldspar, etc.) together with some dolomite are floated from the collophanite in column flotation cells with an amine in order to meet product specifications (31 % P205) (Service et al.). In other cases, such as the SF Phosphates Limited Mine, Vernal, Utah, the ore is treated by traditional fatty acid flotation of the collophanite with mechanical flotation cells (Weber, 1986). Preliminary tests have now been conducted to evaluate air-sparged hydrocyclone (ASH) technology for the flotation of western phosphate ore. For this preliminary study, samples were taken from the hydrosizer overflow stream (18-21 % P205) at the SF Phosphates Limited Plant in Vernal, Utah for scavenger flotation testing with the 2-inch ASH system in laboratories at the University of Utah. Selected design and operating variables are being studied, and the initial results show that satisfactory separations can be achieved by high-capacity ASH flotation at appropriate operating conditions. For example, with single-stage ASH flotation 80% recovery can be obtained with a scavenger concentrate grade of about 26% P2O5. These results are comparable to, or better than, those obtained at SF plant operations with conventional flotation cells and suggest that ASH flotation technology can be used to good advantage in the phosphate industry. Of course, research should be continued to consider other process streams, optimize the separation efficiency, and evaluate larger diameter ASH units.

Jan 1, 1993

By Terry A. Lee

The grade of mineral resource estimates underpin all major economic considerations of mining prospects. While there are reporting requirements to satisfy when stating a mineral resource estimate, an examination of NI 43-101 style reports suggests that authors believe that there are a number of ways of addressing these requirements. As a reader of these reports, some processes are helpful and others are not so in getting a real appreciation of how realistic is the mineral resource estimate. Critical to the quality of the mineral resource estimate is how realistic is the economic mineral concentration component. In many cases, this parameter is called grade. The industry experiences increased difficulty in achieving realistic grade estimates as the sample grade variability increases. The level of transparency in a mineral resource estimate is very much a function of the competence of the author. An objective presentation of the critical data, such as grade sampling variability can assist a reader in determining if the geology of the mineral concentration is adequately understood and how realistic is mineral resource grade estimate. This paper has considered 75 NI 43-101 style reports released in the past 2 years. The review demonstrates features that were helpful in determining how realistic the mineral resource grade estimate is. If there is insufficient transparency in a report, there is a high probability that the mineral resource grade estimate will not be realistic.

Apr 1, 2005

By John J. Gordon, Neil K. Cooperrider

The International Organization for Standardization (ISO) standard ISO 2631 [1,2] provides three methods for evaluation of human exposure to vibrations that contain occasional shocks or impacts. Part 1 of the standard specifies the running r.m.s. or maximum transient vibration method (MTVV) and the fourth power vibration dose value (VDV). Part 5 of the standard provides a method of computing the stress in the lumbar spine for humans exposed to multiple shocks. Alem et al [3] have reported application of these methods to data for tactical ground vehicles. This paper reports and compares VDV and spinal stress evaluations of more than 90 hours of vibration and shock measurements on North American locomotives engaged in through freight operations. The measurements evaluated in this paper were obtained for full crew shifts on 19 freight locomotive runs on mainline track in locations from New York to California. The shifts ranged in duration from 187 minutes to 497 minutes. The average speeds for the shifts were from 21.0 mph to 54.6 mph. All measurements were made on locomotives hauling freight trains in regular revenue service. Data Acquisition and Processing The results reported here were computed using test data acquired from a tri-axial seat pad, accelerometer at a sample rate of 400Hz with an anti-aliasing filter corner frequency of 100Hz. The VDVs and the lateral and longitudinal spinal stress values were computed directly from the acquired test data according to the procedures specified and described in [1] and [2]. The vertical spinal stress values were computed by converting the as-acquired test data to a sample rate of 160Hz for input to the vertical spine model, as required in [2]. The conversion of the test data from the as-acquired sample rate of 400Hz to the required sample rate of 160Hz involved up sampling or interpolating the test data to an equivalent sample rate of 800Hz, band limiting the resultant data with a low-pass filter corner frequency of 60Hz and finally down sampling or decimating the 800Hz data to a sample frequency of 160Hz. Discussion The vertical VDVs computed according to [2] for the 19 shifts ranged from 2.68 to 9.33 m/s1.75. In all but one case, the vertical values were greater than the values for the lateral or longitudinal directions. Note that the health guidance in [1] puts the lower boundary of the health guidance caution zone at a VDV value of 8.5 and the upper boundary at 17 m/s1.75. The daily equivalent static compression dose computed following [2] ranged from 0.123 to 0.434 MPa. Health guidance provided in [2] states that there is a low probability of an adverse health effect if the daily dose is less than 0.5 MPa.

Jan 6, 2006

By Rod L. Norfleet

Cemented tungsten carbides are a sintered powder - metallurgical product essential to modern industry. Because of their moderate unit price and our dependence upon foreign sources for the component raw materials, a growing recycling industry has developed in the United States. There are two basic approaches taken to recycling cemented carbides; those which leave constituting materials unaltered or direct-reuse and those which separate the constitutes back to the raw components. To separate the carbides back to their raw components usually requires expensive chemical processing and is thus confined to the lower value materials such as grinding sludges. The direct-reuse methods recycle cemented carbides back to an intermediate level, a powder capable of being recompacted and resintered into a functional end-product. The three most commonly used methods of direct-reuse recycling, the coldstream process, bloaching and the Bernard or zinc process, are reviewed,

Jan 1, 1984

By William Hodder, Ehsan Alavi, Nader Ghasempour, Daniel Cressman

The Don River & Central Waterfront Coxwell Sanitary Bypass Tunnel (CBT) Project in Toronto will extend approximately 10.5 km from Ashbridges Bay Treatment Plant west under Lake Shore Boulevard, north under Bayview Avenue and east through the Don River park area to the Coxwell Ravine Park. The tunnel is currently being mined by using a shielded dual-mode tunnel boring machine (open and close) capable of operating in EPB mode and lined by using a precast concrete segmental tunnel linear with an internal diameter of 6,300 mm and external diameter of 6,900 mm. The CBT is expected to be excavated mainly through shale bedrock of the Georgian Bay Formation, at approximately 50 meters deep. The tunnel crosses a buried bedrock valley in two locations, in the southern portion of the alignment, adjacent to the Don River, and at the northern portion of the alignment approaching the CX-1 shaft. In these two locations, the bedrock cover is expected to be less than 6 meters. The risk of encountering weathered bedrock, significant ground water inflows or surficial soil deposits through these buried valleys was identified during the design phase. The contract required the TBM to be designed with the ability to probe drill ahead of the TBM and convert to EPB mode if necessary, to cross this area. This paper will discuss the additional exploration that was performed by the contractor to identify the extent of this buried valley, the plan going into the zone of potential weathered shale, and the actual conditions encountered.

Jun 13, 2021

By J. Koster

During the past several years, alunite from the Marysvale (Utah) region has been the subject of investigation by the Electrometallurgical Section of the Bureau of Mines. The nature and occurrence of this mineral, with considerable data on the Utah deposits, together with a number of results of preliminary experiments, have been given in a previous report.6/ The geology of the Marysvale region has been reviewed recently.7/ The present paper reports the results obtained by a method involving the sintering of alunite with boric acid and subsequent treatment of the sinter to produce alumina and potassium sulphate.

Jan 1, 1939

By A. C. Stevenson

IN OUTLINING the various steps taken and the exigences met during the time of unwatering and rebuilding the burnt top equipment at the Hecla mine, the major portion of the detail is omitted and a general description of the experience only is given. All the electrical power lines were out of commission, as were the mine feeder cables. The first effort, there- fore, was to restore electrical connections. The Washington Water Power Co. immediately put a crew to work restoring the power line, it being necessary to rebuild about 4000 ft. of 66,000 volt transmission and about 2000 ft. of 2200 volt feeder. This work was rushed and power was again available at the mine sub- station about 26 hours after the fire. During the same time temporary lighting lines were strung and transformer equipment obtained, so that when electrical connection was resumed the lights were turned on and the dump well lighted that night.

Jan 1, 1924

The Energy Authority of NSW has wide powers and responsibilities conferred by its Act which are pertinent to the State's coal industry and its development into the next century. With respect to coal, the broad objective is to maximise the benefits to NSW and its people derived from the State's coal resources. The initial focus of the Authority's coal-related activities in the late 70's and early 80's was on petroleum substitutes from coal. Research was supported, especially on hydrogenation, and the Authority participated in the Joint Australia/Federal Republic of Germany coal-to-oil feasibility study. It also co-ordinated a State Government initiative to involve the private sector in examining the possible establishment of a synthetic fuels industry based on Hunter Valley coal. With a short-fall in world-wide petroleum supply now seen as less likely for some years, the Authority is looking also at ways of working towards the broad objective in the field of coal utilisation on both domestic and export markets. Areas of interest include possibilities for using washery rejects, means of making NSW coal more competitive as an energy source, use of coal-seam gas and new or special technologies for burning coal. The future is expected to see renewed interest in producing petroleum substitutes, and coal - as the State's major energy resource - is seen as a strong contender as a basis for such an industry. Developments in coal-based power generation are also expected to have an impact, with advanced technologies having a possible place here as well as Overseas.

Jan 1, 1987