Search Documents

By Bianca Proença

Fotocatalisadores de nióbio foram obtidos por anodização a 15 V, utilizando uma solução de K2HPO4 10% p/p em glicerol anidro como eletrólito por 15 minutos. As amostras foram caracterizadas por difração de raios-X para avaliação da estrutura cristalina obtida. A fotodegradação do glicerol (utilizado como agente de sacrifício) foi avaliada pela técnica de cromatografia líquida de alta eficiência.

Aug 16, 2017

By Liu bing-guo, Peng Jin-hui, Guo Sheng-hui, Kong dong-cheng, Hu jin-ming, Zhang Li-bo

The novel technology of calcination to prepare triuranium octaoxide（U3O8）from ammonium uranyl carbonate in microwave fields was investigated on the basis of the temperature rising characteristics of ammonium uranyl carbonate, triuranium octaoxide (U3O8), and their mixture. The result of experiments show that ammonium uranyl carbonate had weak capability to absorb microwave energy, while triuranium octaoxide has the very strong capability to absorb microwave energy and the sample temperature increased rapidly with an increase mixture ratio of triuranium octaoxide. The optimal calcination conditions were as follows: microwave power 700 W, calcination time 10 min and 60 g in this experiments range, respectively. Under these conditions the value of total uranium and 4 U of triuranium octaoxide was 84.28% and 31.02%, respectively. It is feasible to prepare triuranium octaoxide by calcination from ammonium uranyl carbonate, which mixed with small amounts of triuranium octaoxide under microwave fields.

Jan 1, 2015

In this very interesting paper, Mr. Harrington mentions a considerable variety of materials suitable for use in the rock dusting of coal mines; this suggests that you may possibly be interested in same purely theoretical figures tending to show the superiority of gypsum for this purpose. Some of the gentlemen present have found difficulty in applying a thick, adherent coating of dry gypsum to the ribs and roofs of their workings, for which reason pulverized gypsum will perhaps be chiefly useful for the loading of barrier troughs. In view of the function that rock dust is expected to perform in case of a coal-dust explosion, it seems obvious that the most efficacious dust will be the one that can absorb the most heat and absorb it most rapidly. The customary rock dusting materials differ considerably in this respect, depending principally upon the facility with which they can be decomposed at the temperatures encountered in a coal-dust explosion. Such stable materials as silica, anhydrite and flue-dust vary but slightly in their heat-absorbing capacities, the specific heats of minerals in general ranging between 0.19 and 0.22; on the other hand, gypsum and limestone, as well as certain argillaceous materials such as shale, adobe, etc., are capable of absorbing additional heat through their chemical dissociation, although, as will appear later, it is questionable whether the amount of heat thus absorbed, in the case of limestone, shale, and adobe, is large enough to have any practical value. As to the temperature developed by a coal-dust explosion, the Bureau of Mines reports one test in which gold foil was melted, and others in which silver foil was melted, but not gold; hence 1832° F. (1000° C.) seems a reasonable figure to assume for purposes of calculation. Normal temperature is taken as 68° F. (20°C.). The other fundamental data required for the computations as cited by various authorities, are as follows: [Specific heats Gypsum : 0.259 Calcium sulphate, anhydrous. . .190 Limestone 0.216 Lime 0.239 Clay, shale, silica, etc. usually not exceeding 0.220 Carbon dioxide .:0.217 Steam (at atmospheric pressure)0.500 Heats of formation CaSO4+2H2O-4.606 Kg-cal. per gram molecule, or 48.2 B:t:u.' per pound of gypsum.- CaO +C0,42.5 Kg.-cal. per gram molecule, or 765 B.t.u. per pound of limestone. Latent heat of vaporization of water. from and at 100°C.. 535.9 Kg.-cal. per kilogram (964.6 B.t.u. per pound).] Computations will be based on the Fahrenheit scale and British thermal units, as probably more familiar in the coal industry. First as to the inert materials: their heat-absorbing capacity per pound is simply the product of their specific heat, say 0.22, multiplied by the assumed rise in temperature, 1764° F., or 388 B.t.u. per pound. Gypsum, CaS0, 2H.0, though apparently perfectly dry, contains 21% of combined water. When gradually heated it will have liberated three-quarters of its water freely by the time it reaches 250° F.; the remaining one-quarter is retained to a somewhat higher temperature, but the last of it will have been expelled at 482° F. For calculating the total heat absorbed in raising gypsum (or its products) to the temperature of a coal-dust explosion, no serious error will be intro-

Jan 1, 1925

By Cornelius F. Kelley

EVERY man connected with the mining industry should take a significant pride in the fact that he belongs to an industry and to a profession that, from the beginning, has been constructive. The miner digs his ore and he gives the metal to art, to industry, and to commerce. The nature of our business is destructive only in that we deal with a wasting asset. That should be a source of great pride to those who belong to the profession. But unfortunately, the product of our mines, our smelters, and our re- fineries does not always go to constructive purposes. There are times when, in the administration of the affairs of men, our product chiefly goes to purposes which are destructive. When we look upon the panorama of horror that is being enacted throughout the world today, we wonder whether any effort toward the development of civilization and culture and education and well-being has been worthwhile. We are appalled to see the things that have been developed, through the application of science, toward progress and efficiency, now used for the catastrophic destruction of those things which are the most valuable that man has built. We must find hope that this is but an episodic thing; that it must, in the infinite wisdom of the Almighty, usher in a period of peace and progress, of civilization and development that will make man's existence upon earth worthwhile.

Jan 1, 1941

By C. K. Arthur, N. K. Dumakor-Dupey, B. A. Kansake, F. A. Kaba

Autonomous mining systems have been deployed for improving mine performance. However, there is a fear of job losses. Adoption of autonomous systems is envisaged to be resisted by major stakeholders in Ghana due to high illiteracy and unemployment. This paper assesses the preparedness of Ghanaian mining stakeholders for the adoption of autonomous systems to Ghana’s surface mining industry. Closed and open-ended questionnaires were administered to mine stakeholders. Respondents generally expressed unwillingness to accept autonomous systems into Ghanaian mines due to fear of increased unemployment. We propose setting up a mining education fund (MEF) for training stakeholders in autonomous mining systems. INTRODUCTION Mining contributes enormously to the sustenance and growth of global and national economies through the provision of raw materials, employment, revenues and foreign exchange (Carvalho, 2017; ICMM, 2017; Cordes et al., 2016; Solomon et al., 2008; Walser, 2000). The International Council on Mining & Metals (ICMM, 2014) reported that globally, formal mining employs approximately 2.5 million people. Many resource-rich countries, especially the developing ones, have experienced strong socioeconomic growth propelled by the discovery and extraction of valuable minerals. McMahon and Moreira (2014) reported a positive linkage between mining and sustainable development. They revealed that averagely, resource-rich countries have improved Human Development Index (HDI) scores than countries without mineral resources. Mining remains a crucial industry in Ghana’s economic development (Bermúdez-Lugo, 2016; Amponsah-Tawiah and Dartey-Baah, 2011). Over the years, mining has contributed significantly to the gross domestic product (GDP) of Ghana. In 2013, mining accounted for 1.7% of Ghana’s GDP and about 19% of government revenues (Ghana Chamber of Mines, 2015). The Ghana Chamber of Mines also reported that mining contributed over 50% of foreign direct investment, 37% of export earnings and 1.1% of direct employment revenues. The US Department of Energy (DOE) estimates that 65% of coal, 92% of metals and 96% of industrial minerals are mined using surface mining methods (DOE, 2007). Generally, mining is a capital-intensive venture, with high operating cost, hence there is a constant demand for mining companies to seek efficient cost reduction and production maximization strategies. One strategy being pursued keenly is automation, which is noted to improve productivity, and worker safety at minimal cost. According to Parreira (2013), mining automation involves direct teleoperation whereby workers remotely control the mining process using computers from a control room.

Jan 1, 2019

By G. Wahl, H. Danilkewich, T. Mann

Developers of advanced mining projects face the challenge of how to craft a “Request for Proposal for a Feasibility Study” that will result in bids that are comparable and will lead to a successful execution of the study. Mining engineering consulting firms are challenged by “Request for Proposals” that may consist of a limited description of the Scope of Services and other items, which could present difficulties in the subsequent financing and/or development of the project. Changes in international disclosure requirements have also changed the landscape on how resources and reserves are reported by introducing new disclosure requirements and concepts such as qualified persons. This paper lays out a strategy for preparing a Feasibility Study “Request for Proposal” based on the experiences of a mining engineering consulting firm working on a diversity of projects around the world, and in light of the recent changes in international reporting standards for reserves.

Jan 1, 2002

By Glen A. White

The level of impact and mitigating measures that are forecast in an environmental assessment (EA) for a new, or significantly modified, metallurgical processing facility or mine are taking on increasing importance during the subsequent life of the facility. The basic premise is that one is authorized to operate within the envelope defined by the approved EA. Operations inevitably change as they develop and mature, and at some point, one is faced with the prospect of re-doing the original EA work. This can lead to significant development delays. Cameco Corporation (Cameco) has played a major role in developing the northern Saskatchewan uranium mining industry over the past decade. Through the EA process, the company has developed ideas on what works well in generating approvals that give the operator some future flexibility. Early introduction of concepts for potentially different mining and processing methods, as well as contingency plans if things do not work out exactly as predicted in the original EA, can make subsequent regulatory approval for change a more efficient process. One must also preserve the principles of open consultation upon which the EA process was originally based. As such, involvement and support from local communities and other stakeholders is required to ensure the long-term success of the EA process.

May 1, 2004

By David Ziegler

Rough sketches, field notes, an on-site conference or a phone call may no longer suffice to establish your blast plan at a job site. More and more, general contractors, site supervisors, owner re p resentatives, or the owners themselves want to know details about proposed drill and blast operations at their site, in advance. We are seeing more contracts that re q u i re a blasting plan to be submitted in writing. The purpose of this session is to discuss items that you might want to include and address in a written blast plan, and some ideas about how to present them. This is not intended to be a complete list of items that could be included in a blast plan. Contracts may list specific items that need to be addressed. Only a few of the more common elements will be covered here. The bro a der purpose of this discussion is to get you thinking, about what you might want to include in your own “standard ” blast plan.

Jan 1, 2004

By David Ziegler

A formal blast plan is sometimes required for projects involving rock excavation. A written blast plan submitted with a bid proposal can also be an important sales tool. A blast plan will cover the basic elements of shot design: hole diameter, spacing, burden, loading, and so forth. Some suggestions are discussed here for additional items or topics to address, including: safety issues, ground control, traffic & site control, public relations, pre-blast inspections, seismic monitoring.

Jan 1, 2003

By Chunyang Guan, Jilai Xue, Jun Zhu, Qiaochu Liu

"Al-Sc Alloys have showed many advanced properties for a wide range of industrial application, which is usually produced using thermal reduction process. This work is aimed to develop an electrochemical process to make Al-Sc alloy using industrial Hall aluminum reduction cells. The experiments have been carried out in a lab cell where NaF/AlF3-Al2O3-LiF as electrolyte, Sc2O3 as raw material, and liquid aluminum as cathode were used at operating temperature of 950 °C. The resulting Al contained 0.2 - 0.5 wt.% Sc that is the common range in its content for advanced applications. However, a small fraction of Sc was found from thermal reduction at Al melts interface. SEM-EDS and ICP-AES analysis showed a uniformed distribution of Sc at varying locations of the Al-Sc alloy sample. In addition, a higher Sc content in Al-Sc alloy can be obtained with introducing ultrasound through the cathode than that without it.IntroductionIn recent years, scandium has been investigated as an alloying element for aluminum alloys. With addition of a small amount of Sc, Al alloys can improve the strength, weld ability, resistance to re-crystallization and corrosion resistance [1-3]. Due to their advanced properties and potential applications, the demand for Al-Sc alloys will increase in the future. However, the difficulties in reduction technologies and the high costs in production process may limit their expansion in application areas.The current major method of producing Al-Sc alloys is to mix Sc into Al by melting Al-Sc master alloy. This alloying process has several technical problems, such as easy segregating and heavy burning loss, etc. The price of Sc metal or starting material is also high, so the mixing process is an expensive alloying method. Molten salt electrolysis is alternative method to prepare RE metal and RE alloys [4, 5]. It also can reduce the segregation of alloying elements. Sc2O3 is an ideal material as raw material with low price and decomposition voltage. Some work has proved that Al-Sc alloys can be obtained by electrolysis Sc2O3 directly in cryolite [6-8], or CaCl2 molten salt [9]."

Jan 1, 2012

By F. Palmay, R. D. Gwilym, P. Eng

INTRODUCTION As the experience in Canada indicates, it is becoming more and more common to evaluate major mining projects, especially those relating to uranium, with respect to their environmental effects. As part of this evaluation public hearings are becoming the rule rather than the exception. In this area the 1970's and presumably the 1980's can be characterized as the age of "Environmental Assessments" or "Environmental Impact Statements" which form the basis of these hearings. These documents tend to require significant amounts of research, data collection and effort in their preparation, and tend to be closely scrutinized by the hearing body and by groups in opposition to the project. This opposition is becoming more organized and sophisticated. The assessment or impact document, together with the evidence supporting it during the hearings can: (a) mean the difference between a lengthy and hence costly hearing and a smoother, shorter and less expensive one, (b) result in requirements for extensive modification at the expense of the proponent to his project, (c) result in the proponent being required to carry out extensive studies, research or monitoring programs, and (d) conceivably may in certain situations result in the project actually being turned down. Therefore, while on the one hand it is important to have available technical answers to concerns relating to uranium, its associated and perceived hazards, it is getting more and more important to be able to present these answers in both a written and oral format in such a way as to meet the criticism and concerns of the opposition, be they citizens in general or special interest groups including environmental lobbyists. JURISDICTION From a Canadian perspective, the first legal question to be answered is which level of government has jurisdiction over uranium mines in general and specifically over aspects relating to the environmental effects, including the health and safety aspects, of uranium mines and

Jan 1, 1980

By Louis D. Huntoon

AFTER the completion, in 1905, of the Hammond Mining and Metallurgical Laboratory of the Sheffield Scientific School, Yale University, it became necessary to secure and assay a large assortment of ore-samples, and to arrange the results in such a manner as to admit of use with the least amount of work on the part of the instructor. At first, pulp-samples, together with their respective assays, were secured from the mines, smelters, and public assayers, but this practice did not prove satisfactory. It was not only difficult to secure a sufficiently large supply of material, but it was also impossible to secure the proper assortment required for instructing students. It involved considerable work for the donors to select the samples and furnish a record of the assays, and also for the instructors to examine each pulp and determine its character. Some of the samples did not contain a sufficient quantity of pulp for the student to check his work in case his first assay did not correspond to the record. In order to increase the number of samples and to vary the character of the material, pulp-samples were later mixed with barren rock and with sulphides, but this method also was unsatisfactory and has been discontinued. At present., small lots of ore are secured by gift or purchase from engineers, public assayers, and the managers of mines, mills, and smelters. These lots weigh from 10 to 100 lb. each, and are rarely finer than 0.25 in. in size. The larger samples permit of a careful study by the instructor in order to determine the best method of assaying to be followed. In universities in which assaying is taught the record of the samples should fulfill the following requirements

Nov 1, 1909

By Andrew Allen

WHEN a mine is changed from hand, to me-chanical loading, the character of the coal dumped at the tipple is changed in many ways. Selective mining is not so easy with mechanical load-ers, and where much picking is done at the face it is apt to be wasteful anyway. Much recoverable coal is apt to be lost by too free gobbing and, in my opinion, picking at the face should be confined to removal of heavy rock, such as pieces of roof or bottom or sulfur balls. and to such clearly defined and persistent bands as can be readily recognized and segregated. With mechanical loaders of the shovel type, even this amount of gobbing is almost impossible. When coal is shoveled into a conveyor there should be no difficulty in doing as much picking as now by hand loading. The size of lumps may be greatly increased, on ac-count of the ease of handling them with a shovel, as the miners will not break them up in order to lift them into cars. Fines may be increased. This is, of course, not universally true, yet it is my opinion that a shovel breaks the coal more, as a rule, than hand loading. This might not be true with all types of shovels and is cer-tainly not true with a conveyor, either with or without the "duck-bill." The average car load will be greatly reduced in fields such as Illinois and Indiana, in which it is the practice to build up the coal above the sides. Where "level full" regulations prevail there should be no material change. When the coal comes to the tipple these differences usually result in the discovery, that many changes are necessary in the preparation plant. The increase in the percentage of fine sizes will probably not bother the screen, but may overload the conveying apparatus. The larger size lump may clog the chute, but as a rule the efficiency of the sizing screens is not greatly affected. In one completely mechanized mine the proportions of 6-in. lump and 2-in. screenings, when loading by hand, were 16.9 and 51.3 per cent respectively. When loading mechanically, these proportions changed to 15 per cent lump and 53.5 per cent screenings. The picking force on the tipple has been increased from 14 on hand loading to 33 men on mechanically-loaded coal. This is for an output of about 5000 tons.

Jan 4, 1927

By Joel L. Morrison

The preparation of coal-water slurry fuel (CWSF) has the potential to be a commercially viable technology for the coal industry. The technology base required to prepare stable CWSF using grinding circuits has been developed over the past decade and is now being applied to the preparation of CWSF from wet coal fines which are generated during coal beneficiation. When preparing CWSF, the optimum CWSF formulation must be determined to ensure that the fuel will be stable while having acceptable atomization and combustion properties, and the production run must be monitored closely to ensure that the CWSF quality is maintained. This paper describes the CWSF formulation process, CWSF preparation circuits, and some of typical problems encountered in, and solutions to, the transportation and storage of CWSF.

Jan 1, 1993

By C Tickell

Achieving occupational health and environmental noise objectives is a major consideration in the planning or operational phase of resource development and industrial projects to meet the needs of the workforce and community and comply with legislative requirements. For material handling systems, ventilation plants, mobile equipment, process plants and fixed infrastructure, noise emissions need to be considered at the design phase. The preferred approach is to provide noise emission technical specifications, but in many cases this is not stipulated. An occupational noise requirement, such as ‘not to exceed 85 dBA at 1 m’, is often provided, but this will not achieve the required occupational or environmental noise objectives and may cause overly stringent requirements when they may not be needed. It should be noted that when developing the technical specification, measuring compliance needs to be taken into account as, in some cases, measuring may be very difficult or even not possible.This paper will discuss the requirements for providing an effective noise specification that ensures the environmental and occupational noise objectives are able to be achieved and that, once installed, compliance can be measured. It discusses planning such as when to set the objective, correlating the appropriate objectives for the environmental and occupational noise requirements, allowing for measurement tolerance, providing a suitable criteria and data format for the suppliers to respond to and methodology to measure compliance. Different phases of a project require different approaches to planning for noise management and these will be discussed in the paper. Examples from 35 years of industry experience will be included.CITATION:Tickell, C, 2016. Preparing effective specifications for occupational health and environmental noise objectives in mining project design and delivery, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 781–788 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Ruirui Wei, Mingrui Yang, Xuewei Lv

Copper slag is a by-product obtained during smelting of copper from copper ores. In China, for one ton of metal production about 2.2 tons of copper slag was generated, and approximately 15 million tons slag is produced in 2013. Dumping and disposal of such huge quantities of slag will cause environmental and space problems. Most importantly, copper slag cannot be made full use of to maximize its value. In this study, copper slag was used to take the place of scrap iron and part of silica in traditional process and to produce FeSi alloy as the main material. Utilizing silica and copper slag as the raw materials and coke as the reducing agent, FeSi45 was produced in the induction furnace. In addition, the effect of different n(C)/n(O) on FeSi45 has been investigated.Increasing n(C)/n(O) is beneficial to form the stable phase of FeSi. Meanwhile, n(C)/n(O) greatly affects the reduction and recovery of silicon than iron. When n(C)/n(O) equals 1.10, the recovery of silicon and iron is about 77 and 95%, respectively.

Mar 1, 2017

By Valerie A. Rhodes, Catherine T. Aimone

Often blast damage litigation involves structural damage which clearly is not blast related. The fact that structures are observed to be damaged when blasting has taken place in the near vicinity of these structures does not necessarily mean that the damage was caused by blasting. If careful blasting and seismograph records were kept by the blaster which decisively indicate damage is not blast related, then other causes of structural damage need to be assessed. These include problematic soil characteristics and long-term changes in climate or subsurface soil moisture. This paper presents the evaluation process required to investigate soil problems leading to damage often attributed to blasting.

Jan 1, 1991

Safety and health are no longer secondary responsibilities but must be of paramount concern to every mining operation, according to Anthony J. Thompson, an attorney with Hamel, Park, McCabe & Saunders of Washington D.C. The Mine Safety and Health Administration (MSHA) forecasts an estimated 19,000 inspections during 1979, and the economic and psychological impact of these inspections may he significant. To illustrate his point Thompson reviewed the experiences of a relatively large operation during a recent MSHA visit. The inspector was on the premises for two months, issuing between 250 to 300 "significant and substantial" (s&s) citations. During the most intensive period, about one month in duration, the operation experienced a production loss estimated between 2500 to 3000 tons; an accident rate up 30% over the previous month and 20% over the same month in the preceding year; 100% of the safety director's and safety engi¬neer's time was devoted to the inspection; 50% of top level management's time; and 90% of the mid-level or front line supervisory's time.

Jan 11, 1979

By C Mason, A Littleboy

This paper presents the results of a large scale survey of The Australasian Institute for Mining and Metallurgy (AusIMM) membership. This survey aimed to understand and define the key issues and drivers that AusIMM members perceived would shape the development of the Australian minerals industry over the next 20 - 30 years. Nine hundred and fifty-nine participants rated the importance of 11 issues and six drivers (generated from interviews with AusIMM members), and 236 of these participants also provided qualitative descriptions of the future. Issues were defined as problems or opportunities for the minerals industry that may be controlled or influenced by the industry, while drivers were defined as those factors that will influence the direction of the industry that are not within the control of the industry. The quantitative data revealed that the top four issues, in order of their perceived importance to the Australian minerals industry, were: investment in exploration, workforce, health and safety, and innovation. The top three drivers in order of their perceived importance, were: economics of mining, global context and Australian society. While the top four issues were largely consistent across professional groups examined, metallurgy and mineral processing professionals rated water inputs and energy inputs significantly higher than the other professional groups. For the list of drivers, there was strong agreement regarding their ranked order of importance across the professional groups examined. Within the qualitative data, however, a single issue (technology) and a single driver (economics of mining) dominated participantsÆ descriptions of the future. These findings provide important input into a broader program of scenario development for the Australian minerals industry being undertaken by CSIRO and its partners. The results of this study demonstrate the importance of using a mixed methodology in generating these inputs to understand more fully how important stakeholders view the future and the factors that will shape it. The results of this study are also discussed with respect to the role that CSIRO may play in facilitating the exploration of uncertainty around the future of the Australian minerals industry.

Jan 1, 2009

By Samuel Frimpong

The preparation of graduate talent for the mining industry is a challenging process, given the multifaceted and complex array of decisions mining engineers make in discharging their responsibilities. As leaders, mining engineers must manage operations, lead project teams, mentor junior engineers, chart the technological directions of companies and deal with several organizations for maintaining the technical and economic feasibility of operations within strategic and tactical framework. Traditionally, the completion of the bachelor of science degree curriculum, with a minimum cumulative grade point average (CGPA), has been used as a graduation measure by Missouri University of Science and Technology (Missouri S&T). Companies have long realized the limitations of the CGPA for recruiting graduates because mining engineering is an applied engineering discipline. Company recruiters have sought to correct the limitations by factoring experience and behaviors into the selection process when recruiting knowledgeable and well-rounded graduates. In this paper, the authors introduce a new metric, which combines the current CGPA (knowledge) with experience and attribute (KEA) metrics to gauge the job readiness of graduating engineers. The KEA metric, also called the job-readiness factor (JRF), is the sum of K (50%), E (30%) and A (20%). The KEA process has been applied to a graduating class in Missouri S&T to demonstrate the value of the new metric system. The results show a fairly positive correlation between CGPA and the KEA metric, with a coefficient of determination of about 70%. Overall, the KEA metric system provides a better picture of the capacity and job readiness of graduates entering the workforce.

Jun 1, 2013