Search Documents

By F J. Pearce

The Steel Company of Canada, utilizing the S-L process, has produced partially and highly reduced pellets for use in the blast furnace. Experimental blast furnace tests, using reduced pellet burdens, have been carried out. The changes in production rate, fuel rate and general performance of both the S-L and the blast furnace processes are indicated. Introduction T HE ore burdens for a blast furnace may be improved in two ways: chemically, by concentrating the ore to a high degree of purity; and physically, by agglomerating or closely sizing the ore particles. Today, many b1ast furnaces are charged with closely sized agglomerates, some of which contain upwards of 66 per cent iron. The further improvement of these burdens by chemical concentration may, in many instances, be uneconomic due to the large losses of iron that occur during processing. Assuming that it would be possible to reject all of the gangue minerals, the maximum level of concentration of iron in the hematitic ores would be only about 70 per cent.

Jan 1, 1964

By V. Dentoni

The paper deals with the assessment of the visual impact generated by surface mining and quarrying. Previous research works proved the applicability of an indirect method based on the elaboration of digital images through which the extent of the visible altered area and the chromatic contrast with the surrounding environment is calculated. The resulting level of visual impact allows an objective comparison among different cases as far as the evaluation procedure is univocally defined. The article illustrates the application of the method to a number of selected quarries located within the Sardinian territory; different issues are discussed such as the choice of the viewpoints from which the pictures are taken, the influence of the distance from the quarry to the selected viewpoints, the light condition and the orientation of the quarry faces. Moreover, the visual impact level obtained from pictures taken at the same time with five digital cameras are compared in order to evaluate the contribution on the overall uncertainty.

Jan 1, 2008

By Brian Sandhuas, Robert McClure

All flyrock incidents have the potential to result in injuries or fatalities that can result in loss of company reputation, license to operate with clients, and bear the exposure to high cost liability. From 2007 to 2009, one North American Quarry and Construction Business experienced a series of flyrock incidents. In the spring of 2009, this business declared that the frequency and severity of Flyrock Incidents had reached an unacceptable level. A Flyrock Elimination Program was launched.

Jan 1, 2012

By D Cliff

"It has been 17 years since the mine disaster at Moura No 2 Mine in Queensland. Recent disasters in the USA and New Zealand prompt the question what has changed since 1994. This paper att emptsto answer this question and identify areas that need improvement."

Jun 1, 2012

By Alban Lynch, Benigno Aquino, Hakan Dündar, Alexander Kalugin, Marco Delgado, Alberto Palomino, Ali Türkistanli

Dynamic separators are efficient dry classifiers because new designs during the last 50 years have reduced the by-pass and improved the partition curve. By contrast cyclones have been used as classifiers in wet grinding circuits for 50 years but without serious change and the early problems which were caused by high and variable by-pass, and different mineral specific gravities, still exist. High frequency screens are now used for wet separation and the operating characteristics of closed grinding circuits using cyclones or screens are discussed. Data come from circuits at the Condestable, Cerro Lindo, El Brocal and Catalina Huanca mines in Peru, the Eczacibasi mine in Turkey, and the Apatit mine in central Kola Peninsula in Russia. All classifier data are described by their partition curves and all mill data by their breakage rates. With cyclones the by-pass, d50, and sharpness of the partition curve change as operating conditions change but with high frequency screens the values vary little because the by-pass is low, the sharpness is high, and d50 depends on the aperture size. Data from all plants indicate that lower by-pass and sharper separation improve breakage rates and throughputs. An initial model of the screen is proposed.

Jan 1, 2014

By M. S. Badollet

Introduction Very little fundamental research has been done on asbestos fibre to cake maximum advantage of its properties and to determine in what commercial products it can best be utilized. For the research chemist who is associated with asbestos development work, a thorough study of mineralogical information on asbestos deposits would furnish reliable information on the rock formations and the mineral impurities closely associated with the asbestos. Furthermore, ?he must have an intimate knowledge of the uses of the fibre in various products so that he can visualize the importance of the fibre and the role it plays in industry. Some of the properties of asbestos fibres such as strength, composition, length, harshness or softness, and mineral associates are of considerable importance to the manufacturer because they are responsible for many production difficulties. Fibre Strength It has been known for some time chat asbestos filaments have considerable tensile strength. These strengths have been referred to merely as 'weak' to 'very strong'. Not until recently have numerical values been applied to the strengths of asbestos fibres. But today we can take a thin fibre filament and mount it between two holders and apply a gradually increasing load or pull until the fibre breaks. By measuring the cross sectional area of the filament and the amount of load applied, we can calculate the tensile strength of the fibre in terms of pounds per square inch. This type of test is slow and rather difficult, but the fundamental data obtained furnish important basic information that can be applied to mechanical processing equipment and to certain asbestos products.

Jan 1, 1948

By Brad Grothen

What is the most economical way of tunneling in mixed ground that may experience high pressures? Non-continuously pressurized, mixed ground Tunnel Boring Machines (TBMs) are being utilized to deal with a wide range of geology. Continuous improvements in these mixed ground machines allow for ever-increasing efficiency and reduction of project risk due to unexpected conditions. We will explore the performance of recent mixed ground machines throughout the world and then look at how new improvements to mixed ground machines will enable excavation of an expanded range of ground conditions. These conditions include mixed ground with low fines, mixed face rock, and fracture/fault zones with high pressures where in the past a Slurry TBM may have been utilized.

Dec 1, 2022

By P. V. Brough, K. B. Gillaspie

DECISION to build a mill at the Bayard property was made in May 1942. Western-Knapp Engineering Co., of San Francisco, assisted by engineers of U. S. Smelting, handled the design and construction. Much of the milling equipment was moved from the Company's mill at Goldroad, Ariz. Wartime restrictions necessitated wood construction and paper sheathing except for structures adjacent to the Bullfrog shaft. Construction started in September 1942 and milling in March 1943. Bayard ores are processed in a single-ection mill. About half of the ore treated during the past year was hoisted through the Bullfrog shaft and the rest was trucked from other shafts. Coarse storage includes four bins, two of 120 tons each for Bullfrog ores and two of 85 to 120 tons each, served by a truck ramp. The low capacity figure refers to

Jan 1, 1948

By J Player, G Sweby, S Webber, E Jones

Seismic systems are a tool for the monitoring and forecasting the rock mass response to excavation. Common issues encountered at mine site audits and reviews are: how to design an effective seismic system, implementation of the design, interpretation of seismic source results and understanding the reliability of the seismic source. These issues are often a function of several items including: • Experience of site personnel in undertaking seismic system design. • Personnel not envisioning multiple phases of system expansion to understand system robustness issues. • System design/expansion occurring in response to damaging seismic activity rather than planned expansion of a system • The mine access development is often localised in comparison to the total orebody being mined hence, planning sensors in longholes in advance of development rather than in short holes close to development will improve the three-dimensional aspect of the network. • Limited site processing of the seismic event data, hence engineers do not see the uncertainty associated with event location, size, source and system layout. Mine site users require a framework to appreciate the challenges and limitations in locating large events. For example, event locations are given as precise measurements (to the nearest centimetre) whereas the volume of deformation resulting in the event often has dimensions of tens of metres or more (as defined by the source radius). A stronger awareness of the uncertainty of rock mass yield within large seismic sources will assist site users in the interpretation of rock mass damage. The encountered design and implementation errors are reviewed and discussed with a practical set of rules presented to provide a robust seismic system that provides consistent results and increases the user’s understanding of uncertainty in source location and size. The authors’ experience across multiple mine sites, seismic systems and damaging seismic events over a 30 year period has been summarised into practical rules for site personnel of all experience levels.

Nov 29, 2022

By R. T. Artz

Disposal of sewage is an important part of mine sanitation. Improper... handling and.disposing of sewagerare conducive to the spread of disease and often add foul and nauseating odors to the mine air. The diseases spread by unsafe methods of disposing of waste in mines are typhoid fever, cholera, amebic dysentery, hookworm, and other intestinal diseases due to parasites. Sanitary toilet facilities, with a good sewage-disposal system, each maintained in good order at all times, should help to prevent the spread of diseases transmitted by intestinal body wastos. The metal and nonmetal-mining industries have recognized the impor-dma tance and need for disposing sewage properly; accordingly, facilities of some sort are installed and need today in most large mines. The coal-mining industry has given little thought to the disposal of sewage underground; however, in most mines of the anthracite industry, the inflow of large vol- unes of highly acid mine water and the extensive drainage system required to remove this water provide a natural means for disposing of sewage.

Dec 1, 1946

By Dachun Liu, Wenlong Jiang, Guozheng Zha, Liang Hu

In this paper, a novel technique for recovery of gallium and arsenic by thermal decomposition under vacuum is presented. The effects of distillation tem- perature on the volatilization behavior of each component were investigated. Theoretical calculations and experimental studies have shown that the method is feasible. The results show that under optimum conditions, highly pure Ga can be extractedwithadvantagesoverconventionaltechniques,includingsimpleoperation andenvironmentalfriendliness.Forexample,metallicgallium(purity > 99.99%)is obtained at 1273 K after 3 h under 3–8 Pa. Arsenic is obtained in the form of a elementary substance which could be preserved with relative ease. (cid:1) (cid:1)

Mar 1, 2018

By Joel Werner

Weak metal prices, declining head grade, and increased operational costs are forcing many open pit mining companies to look to their balance sheets for significant cost reductions in order to remain competitive. Maintenance continues to represent a significant proportion of the total operating costs in the mining industry. Compared with the other major cost components of the mining process very little effort has gone into maintenance optimization. The potential payoff from maintenance optimization on the cash cost of the commodity is enormous. A large percentage of these costs are incurred in unscheduled maintenance events, which typically cause serious disruptions to the production process. These maintenance induced production losses can be a significant contributor to the overall operating costs. A structured proactive maintenance approach using the latest advances in technology can achieve dramatic cost reductions and productivity improvements. Remote condition monitoring systems are becoming increasingly commonplace and have the potential to identify problems prior to failure. Detection of equipment degradation prior to failure will enable repairs to be scheduled thereby reducing costs and interruptions to production. Remote condition monitoring technology has evolved rapidly in recent years, with a host of new tools becoming available to assist mine operators in improving their maintenance operations. These tools have capabilities such as: remote real-time vital signs and performance monitoring, alarm/event handling, trend analysis, and maintenance workflow management. When these monitoring tools are used in conjunction with a mine management system the vital signs data can be integrated and associated with maintenance history, predictive maintenance data, operational information, and geographical information. This integrated approach to the management of vital maintenance data will help shift the mobile equipment maintenance paradigm from reactive to proactive. This paper will introduce a proactive approach to the management of the maintenance process and the tools required to facilitate this process.

May 1, 2003

"Beneficiation of low grade ores is the process of increasing the grade of a mineral through unit operations that remove and separate the waste (or gangue) material from the valuable mineral that can then be used for further processing or direct use. Important factors when deciding upon a beneficiation program are the feed grade, mass yield and the metal recovery. As lower grade ores are being processed beneficiation is a critical process. How predictive is laboratory test work for “as built” operating projects? Beneficiation includes all or some of the available unit operations to produce a beneficiation flow sheet i.e. associated unit operations including but not limited to optical sorting, radiometric sorting, crushing and screening, coarse cobbing, jigging, dense media separation (DMS), spirals, magnetic separation, flotation, thickening, filtering and drying. Reference to specific projects and the approach developed in formulating a beneficiation flow sheet and a comparison of difficult and simple beneficiation flow sheets are cited. INTRODUCTIONReserves of high-grade iron ores are reducing all over the world, at an alarming rate, over the years as a result of the rapid increase in demand for steel particularly from Japan and then China. The recovery of mineral value from the low-grade ores using present technology is more expensive than DSO ores due to high energy and capital costs. Beneficiation is defined as a variety of processes whereby extracted ore from mining is reduced to particles that can be separated into mineral and waste.Various physical properties of an ore can be exploited to separate a low grade fraction including variation in hardness, density, reflectance, conductivity and magnetism.""Beneficiation"" of iron ores includes concentration, generally by physical removal of unwanted gangue. Also considered beneficiation is the regulation of product size, or other steps such as agglomeration to improve its chemical or physical characteristics prior to smelting."

Jan 1, 2012

By J. R. MacDonald

MINING literature contains very few descriptions of operations producing as little as 25 to 30 tons of ore per day. The purpose of this paper is to discuss the gradual development of a mining method for such a small-scale operation at the No. 2 mine of Central Patricia Gold Mines, Limited, and in doing so to review several systems of stoping applicable to narrow ve1ns. MAIN ECONOMIC FACTORS TO BE CONSIDERED (1) Overhead.-The outstanding feature of most mines operating on a single narrow vein is chat of small daily tonnage. The reason for this low output can be readily understood. The strictly limited ore-reserves present a condition unfavourable for a policy of large initial expenditures, with the result that the capacity of the plant provided must be governed by the? amount of ore in sight at the time when mill construction is planned. This is immediately reflected in the cost per ton, there being relatively few tons over which to distributed the more or less static charges, such as hoisting, heating, supervision, administration, pre-production expenses, and other write-offs. (2) Development.-In mining this type of orebody, the main factor contributing to high costs is unquestionably the small tonnage of ore made available by a given amount of development. Thus, for example, from the data tabulated below it can be seen chat, assuming a 12-in. vein and a drifting cost of $9.00 per foot, the development charge for this item alone would be 71 cents per ton. Add to this the charges for raising, cross-cutting, shaft-sinking, and pumping, besides charges arising from development in waste, and the figure will be very considerably higher than 71 cents.

Jan 1, 1941

By W. J. Schlitt, K. McNaughton

A heap-leach field test was conducted during the 1993-1994 winter season at Carmacks, Yukon Territory, Canada. The purpose of the test was to demonstrate the viability of heap leaching Carmacks oxide copper ore in an arctic setting on a year-round basis. The test itself utilized a 5-m-diam crib loaded with 250 t of composite ore from the Carmacks copper deposit. The ore was stacked to a total height of 7 m in the crib, including 1 m of ore as an over- layer above the emitter system. This matched the plan for the commercial heap at the time when the test was started. The design also replicated an interior segment of the commercial heap. Leaching was done at a flow rate of 0.2 L/min/m2 using leachate at 21 °C. This temperature was maintained with no external heat input other than normal process heat transferred from electrowinning to the leachate via solvent extraction. Winter conditions were quite typical of those expected at the mine site. The temperature reached -54°C, while averaging -13°C over a three-month period. In spite of some flow system problems, leaching continued unabated, and freezing was limited to the insulating ore over-layer and isolated points near the outer crib walls. Thus, the test demonstrated that year-round heap leaching of Carmacks copper ore is practical in an arctic setting.

Jan 1, 2000

There is a saying, ?If it moves, it vibrates.? This is especially true in our modern industrial environments, where workers use powered tools, machinery, vehicles, and heavy equipment. How workers are affected by these elements of the industrial working environment is a concern of health professionals, govern­ments, and scientists around the world. How to adequately assess the effects of human vibration exposure is an equally important issue. The human body comprises a dynamic structure that is living, intelligent, and complex. Consequently, it is not unreasonable to consider that exposing the body to an array of vibration environments would result in outcomes that are not necessarily simple or easily predictable. Sensations caused by vibration may include nausea, annoyance, discomfort or pain, and exhilaration or pleasure. Many factors contribute to the effects of vibration on humans, including the characteristics of the motion and the exposed indi­vidual, the activities of the exposed individual, and various elements of the environment. There have been attempts to summarize the effects of occupational vibration exposures by simply recommending the avoidance of certain frequencies of vibration or by providing a graphical method, i.e., a single curve displaying all human responses to all frequencies. However, such efforts have not withstood the scrutiny of scientific research and analysis. Thus, attendees and participants at this professional gathering now have the rare opportunity to benefit from the technological advances and new scientific research to enhance their understanding of human responses to vibration that suggest more than a simplistic approach. In the tradition of the First American Conference on Human Vibration (1st ACHV) held in Morgantown, WV, June 2006, the 2nd ACHV provides a forum for scientists, engineers, medical doctors, industrial hygienists, and educators to learn and advance research and education in the specialized area of human body vibration. The conference was organized by the Mechanical and Industrial Engineering Department, University of Illinois at Chicago, with support from the National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Research Laboratory. As with the first conference, the 2nd ACHV provides the unique opportunity to learn about the current activities of peers and colleagues and to exchange information on topics of interest such as human response, human modeling, experimental design, sensors, new technologies, and epidemiological studies of human responses to hand-transmitted and whole-body vibration. The conference organizers hope that the publication of these conference proceedings continues to foster new research and technological advances to reduce health hazards associated with occupational vibration exposures.

Jun 1, 2009

By Robert A. Cummings

A rock mass classification system has been developed for recommending drift support requirements in block caving mines. This development follows a two-year program incorporating field observations of support practice and performance in rocks of different classes, at several U. S. block caving mines. Popular rock mass classification systems presently in use for tunneling were applied at the various field sites; and were evaluated for conformance with caving mine support requirements and for general utility to caving mine operations. The developed system (MBR System) accepts readily-obtainable engineering and geologic data to yield a rational estimate of support requirements. The background and development of the MBR system is described in this report (Volume I). The use of the system is given in the Manual, a separate volume (Volume II).

Jan 1, 1984

By Robert Torbin

The objectives of the Continuous Shaft Lining (CSL) System are to reduce the costs, safety hazards, and time currently required in lining mine shafts with concrete. The CSL will line machine bored shafts downward from the shaft collar on a continuous basis using an inverted, pressurized slipforming technique. The technique for slip-forming downwards has been demonstrated and refined under this program. The approach taken involved laboratory scale testing of key features of the CSL concept. These feature tests included concrete distribution, concrete sealing, concrete slipforming and development of a reliable concrete mix. Based on these results, a full scale above-ground test facility and CSL were designed and fabricated. The objectives of these tests were to demonstrate the viability of the basic concept; to establish operating limits; and to provide input data and information for the design of a second generation shaft lining system. The results of the program have led to a CSL design and operational philosophy which will need to be tested in an underground environment before industry will accept the technology. However, the next generation CSL promises to meet all the original program technical objectives.

Jan 1, 1983

By Llewellyn A. Rubin

ROUTINES AND SUBROUTINES A- 1 Wait Loop (Wait) A- 2 Receiver Processing (RCVP) A- 3 Control Panel Sequence (CPNL) A-4 Interrupt Routine (INTRP) A- 5 Math Processing Routine (PROC) A-6 Input Constants for Math Routine (CONI) A-7 Angle Conversion Routines (LVERT) A- 8 Display Routine (DSPY) A- 9 Message Print Auxillary Routine (MESSO) A-10 Auxillary Subroutines (AFUTC and AGETC)

Jan 1, 1973

By R. A. Cattell

The conditions under which the researches of the Bureau of Mines on petroleum and natural gas were conducted in 1952 were little changed from those indicated in the last report,2/ which dealt with activities during 1951, immediately after crossing of the 38th Parallel by the North Korean Army. Although only a small part of the program was classified in the military sense, there was a feeling of the clash of world forces which called for even cheer scrutiny of the research problems so that the emphasis could be placed without delay where the greatest needs for na¬tional defense seemed to be. The reports of the work accomplished were so directed as to have the greatest immediate value to persons charged with supply planning for the military forces and included information on the availability and characteristics of a wide variety of crude oils, fuels, and other petroleum products. Actually, the approach, direction, and conduct of the work do not differ greatly under the two circumstances, as has been pointed out in earlier reports; only the tempo changes.

Jan 1, 1953