Search Documents

By R. S. C. Rogers

The present study examines the use of two vs. one stage of hydrocyclones in a pilot scale ball mill circuit. The approach used for doing this is based on computer simulation with mathematical models that explicitly account for the grinding mill/classification system interaction. Parameters for the ball mill model are obtained using a short-lived radioactive tracer method in open circuit tests of the study mill. The hydrocyclone model, based on the size selectivity concept, is developed and validated in standalone testing of the study hydrocyclones. Simulation procedures are validated through actual tests of the closed circuit grinding configurations of interest. Results of the evaluation indicate that two stages of hydrocyclones in the study circuit would improve classification, increase productivity and lead to more closely sized circuit products when compared to the conventional one stage hydrocyclone circuit. A computer simulation approach for comparing these circuit configurations in larger scale grinding circuits is also suggested.

Jan 1, 1981

By Christopher J. Bise

It is somewhat reassuring to note that the United States has an abundance of coal reserves which can be used to bridge the widening gap between the nation's energy production and consumption. The U. S. Bureau of Mines has recently established a demonstrated coal reserve base of 434 billion tons. (31)(Figure 1) As can be observed, the major percentage of the reserves is in the West. Although surface coal mining in the West has been gaining increased attention in recent years, western reserves that must be deep mined are significantly greater. Though deep mining activity in the west is very limited and accounts for less than 2% of the annual production, the primary reason, quite probably, is the greater thickness of the seams as compared to those found in the East. Forty-five billion tons of the western demonstrated coal reserve base for underground mining are in seams greater than 10 ft. in thickness. (37) Thick coal seams do not lend themselves readily to extraction with the underground mining methods practiced in the United States today. Experiences from the practices in other countries can serve only as guidelines. Consequently, a concerted effort is necessary to overcome the technical difficulties.

Jan 1, 1975

By K. B. Venkatesh

In view of the importance of size reduction operations from the energy consumption point of view, during the past one hundred and fifty years a number of attempts have been made to develop a general energy-size relationship. However, to date it has not been possible to clearly define the scope of application of various laws proposed, though Bond law has been widely used with a moderate degree of success. It was, therefore, decided to carry out a thorough analysis of the batch ball mill grinding data available in the literature on several minerals that were ground under normal range of operating conditions. In particular, relationships proposed by Bond, Kapur, Voller and Morrell were examined in detail. It was found that the relationship proposed by Kapur in terms of the mean particle size provided a more accurate basis for estimation of energy. The value of the exponent of mean particle size in this relationship, a, is same as the exponent of the particle size in the expression for the grinding rate parameter: ki = Axia, provided the particle size distribution range corresponds to the self-similar or self-preserving regime. In this regime, mean particle size is proportional to the 80 percent passing size and size modulus. From the practical application point of view, it was possible to describe the variation of µ1 over limited, but significantly broad size range, using a constant value of a. Thus, by carrying out a few batches, grinding experiments over the size distribution range corresponding to the contents of the production mill, the applicable value of a can be determined. Keywords: energy-size relationship, ball mill, mean particle size, self-similar size distribution regime

Sep 1, 2012

By Paulo Conceição, Carlos Sampaio, Carlos Petter, Ariane Kuerten

The Sensor Based-Sorting technology is an emerging technology applied in mineral separation and concentration. The technique consists in using a method known as Dual Energy X-ray Transmission sorting (DE-XRT). The particle's position over the conveyor belt was evaluated and, despite de variability of results, shows that there is no a position with greater accuracy on the sensor's reading. Results obtained indicated that DE-XRT sorting technology was able to significantly reduce the mass and the ash content of the ore feed, being an interesting option for reduction of costs and improvement of coal quality in beneficiation plants.

Oct 3, 2019

By Burcu Ertug, Necip Ünlü

"On average, one out of two glass bottles coming on to the market is provided by recycling processes in Europe. Glass recycling has been started by the early of 1970s in Turkey, and the recycling amount has been reached to 70 thousand tons recently, while 4.2 million tons which represents only 25 percent of total glass manufactured, is the amount of glass collected annually for recycling in the world. The glass recycle process basically involves collecting, sorting, then crushing and grinding after which glass cullet is produced as the secondary raw material. Removing of the contaminants from the glass cullet, and then melting are the next steps. In this study, recent developments of 100% recyclable without any deterioration in quality, and never decomposable glass, are discussed detailed in terms of glass production processes.1.IntroductionIn many countries, waste glass constitutes a large proportion of solid wastes, and recycling the glass is a major environmental problem all over the world [1]. Among the diverse types of waste, glass is one of the most valuable recycling materials because it can be revived and recycled completely and hardly decomposes [2]. Between 80% and 85% of the mass output from the worldwide glass industry is either in the form of containers for the food, beverage, and pharmaceutical industries, or flat glass for building construction or for motor vehicle manufacture. Other product segments, whilst only constituting about 15% of the mass output, produce high value technical and consumer products by comparison with container and flat glass [3].In the present study, the recycling of Liquid Crystal Display (LCD), Cathode Ray Tubes (CRT) and Printed Circuit Boards (PCB) were examined. The production of glasses and glass-ceramics from glass cullet, synthesis of different compounds from recycled glass were other subjects of interest. The use of recycled glass for construction industry and using glass as aggregate were emphasized. Finally the recovery of glass fibers were investigated."

Jan 1, 2012

By R. C. Burton

One of the major problems encountered with recirculatory breathing apparatus presently used by mine rescue teams is that the inspired air becomes uncomfortably, and often dangerously, hot. This is also true with self-rescuers. It is well known that man can tolerate very high dry-bulb temperatures if the wet-bulb temperature is low, but not vice- versa. The maximum tolerable, wet-bulb temperature is about 42 °C (108 °F). A continuously inhaled wet-bulb temperature above this value can cause irreversible damage to the throat and lung tissue, and wet-bulb temperatures close to it cause extreme discomfort (1) and seriously retard the capability of the man to perform useful work. A theoretical analysis, combined with experimental results, has shown that it is the carbon dioxide absorbent that is the major cause of high wet-bulb temperatures of the inspired air in the Siebe Gorman Proto 4, and in the Draeger BG 174 apparatus, both of which are used by rescue teams on South African mines (2). In the Proto 4 apparatus, the absorbent for the carbon dioxide is soda lime (calcium hydroxide). The German Draeger BG 174 also uses this absorbent but under arduous conditions such as in hot environments (50 °C, 122 °F), the use of an alkali absorbent cartridge is recommended which consists mainly of caustic soda (sodium hydroxide). Lithium hydroxide is used in some apparatus in the United States. It is clear that different absorbents will produce different quantities of heat and moisture for a given rate of absorption of carbon dioxide. The proportion of this heat and moisture which is transferred to the user depends upon how much can be removed from the recirculating air between the absorbent and the mouthpiece. This paper discusses the present methods of heat removal and describes the design and test results of a prototype evaporative cooler.

Jan 1, 1980

By Bill Loviza, Jimmy Sanders

This report is not everything we would like it to be. Access to information concerning unresolved legal actions is a sensitive matter. Obtaining the information presented in this report was a challenge alone. The Tennessee Department of Commerce and Insurance, Division of Fire Prevention, the firms and individuals that elected to share information did so with various assurances of nondisclosure, confidentiality or anonymity. All those providing information did so with the expectation that the industry and ultimately the public would benefit from this effort. We offer special thanks to Assistant Commissioner, Fire Prevention, Emmett Turner, recently retired Director, Bomb and Arson, Dick Gardner and Director, Codes Enforcement, Randy Safer for support that made this endeavor possible. We make no claim with regard to being a scientific study. We did the best we could with available information. Our task was one of assembly, sorting and reporting. Where collateral information was available we used it.

Jan 1, 2004

By John J. Dran

In recent years, market rates of interest have risen well above their historical long-term average. Also during this period, the short-term variability of interest rates has been greater than in prior years. Interest rates have a significant effect on the operation of our economy. They influence the extractive industries in a number of ways. Their major long- range impact is on investment decisions - specifically the valuation of mineral deposits. An understanding of the factors that influence interest rates is important to the engineer or businessman who makes the investment decisions for the mining company. The effect of changes in the market rate of interest on the value of mineral reserves is critical to the future financial success of the mining enterprise. The most common simplification of the factors determining the level of interest rates is that they are a function of the demand for and the supply of money. While this is an oversimplification, most businessmen would be hard- pressed to provide a better explanation. The purpose of this paper is to explore certain fundamental economic aspects of interest rates and to examine their effect on the analysis of investment in mineral deposits.

Jan 1, 1975

By D. R. Willmer, E. J. Haas

"DISCLAIMER The findings and conclusions in this paper are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Reference to specific brand names does not imply endorsement by the National Institute for Occupational Safety and Health. ABSTRACT This study analyzed the publicly available health and safety policies of 26 mining companies to determine the quantity of health and safety (H&S) practices that mining companies encourage in relation to the Plan-Do-Check-Act cycle. A thematic content analysis of the policies identified elements and practices within the text. On average, companies communicated information on about 7 elements (range 1–14, standard deviation = 3.49) and discussed 15 practices (range 2–34, standard deviation = 9.13). The elements in which companies highlighted the most practices were risk management, emergency management, leadership development, and occupational health. A discussion of the policy trends shows areas that mine sites can improve upon within their Plan-Do-Check-Act cycle, in addition to encouraging the use of both leading and lagging indicators to manage health and safety performance. INTRODUCTION Mining companies and their employees are expected to identify and manage risks at their worksites to ensure the health and safety (H&S) of everyone at the site. The primary mechanism in place to control these risks is a company’s health and safety management system (HSMS) (Boyle, 2012). Broadly, an HSMS is a set of standard, interrelated, and interacting elements used to promote and achieve occupational H&S goals (ANSI/AIHA Z-10, 2012; BS OHSAS 18001, 2007). The practices conveyed within an HSMS are expected to minimize incidents, injuries, illnesses, and even save worker lives (Alsop and LeCouteur, 1999; Arocena and Núñez, 2010). In the United States, both the Occupational Safety and Health Administration (OSHA) and Mine Safety and Health Administration (MSHA) regulate and encourage aspects of an HSMS (US Federal Register, 2011, 2010). Many HSMS documents (i.e., Chemical Industries Association, 1995; Health and Safety Executive [HSE], 1995; International Labour Office [ILO], 2001) attribute the source of their basic management system to Deming’s Plan-Do-Check-Act (PDCA) model of continuous quality improvement and organize their practices within this cycle (Johnson, 2002). The PDCA cycle is a well-adopted approach in health and safety management and promotes continuous learning and adaptability (Robson et al., 2007)."

Jan 1, 2018

By Pooley F. D

The coal measures of the South Wales coalfield contain at least 50 horizons at which coal seams are known, to occur. More than 300 samples of coal were collected from these coal measures and this paper outlines thefindings of an investigation of the pattern and distribution of 12 trace elements in South Wales coals. A comparison of trace element contents of the South Wales coals is made with trace element values found elsewhereand an attempt was made to establish the organic affinity of the elements in different seams and in the coalfield 'as a whole. An important function of such an analysis is to determine the order of abundance of trace elements and this was performed for individual seams and for the whole coalfield.The interrelationship of certain elements in some seams is also examined with a view to understanding the effectiveness of such an approach to seam correlation.Ranges of values are quoted together with the mean values of the various elements. Variations of elemental values within a seam section and over the coalfield as a whole are discussed.

Jan 1, 1977

By Whiten W. J

A simulation model was used to study the performance of various types of screen cloth on industrial vibrating screens. The model takes into account the effect of loading upon screen performance and predicts both themass flow rate and size distribution of the screen products.It was found that the use of the simulation model allowed the reconstruction of data for identical conditions and hence has simplified the analysis of the comparative performance of the screens. The dependence of performance upon operating conditions was found to vary markedly with screen cloth type.

Jan 1, 1977

By Jarrod Bonsmann

"This paper presents the results of small scale testing to examine the effect of various importantparameters on the response of a vehicle due to the detonation of an explosive charge buried inthe soil below the vehicle. In particular, we were interested in examining what effect change instandoff distance, change in mass, and change in surface area would have on the loading applied.We examined the impulse delivered to the target in all cases and for the change in mass andchange in stand-off distance we examined impulse, kinetic energy, and acceleration."

Jan 1, 2012

By Tony Iannacchione

A close look at the Loyalhanna Limestone of southwestern Pennsylvania reveals a complex structural environment. Most exposures of the Loyalhanna occur along Chestnut Ridge and Laurel Hill within the Allegheny Mountain Section of the Appalachian Plateaus Province. Because the Loyalhanna is rated as a super pavement aggregate by the Pennsylvania Department of Transportation and because of its proximity to the population centers of southwestern Pennsylvania, the Loyalhanna has been extensively mined along these prominent anticlinal structures. Geologic and engineering analyses were performed using gas well and core logs, outcrop examinations, underground observations, and mine maps. Strata exposures from both outcrops and quarries were used to construct geologic maps, stereonet, and rose diagram projections so that the Loyalhanna's structural environment could be understood better. Many of these structural conditions cause ground control problems at local quarries. These problems ranged from small-to-moderate sized rock falls associated with roof jointing to pillar failures associated with dipping discontinuities. Stresses ranged from tensional on structural domes where weathering dominates, to high levels of compression within structural saddles. A greater understanding of these characteristics is a prerequisite to develop engineering controls, such as improved mine layouts. pillar sizes, etc., that lessen miner exposure to these hazards.

Jan 1, 2002

By Paul R. Coyle, Anthony T. Iannacchione

A close look at the Loyalhanna Limestone of southwestern Pennsylvania reveals a complex structural environment. Most exposures of the Loyalhanna occur along Chestnut Ridge and LaurelHill within the Allegheny Mountain Section of the Appalachian Plateaus Province. Because the Loyalhanna is rated as a super-pavement aggregate by the Pennsylvania Department of Transportation and because of its proximity to the population centers of southwestern Pennsylvania, the Loyalhanna has been extensively mined along these prominent anticlinal structures. Geologic and engineering analyses were performed using gas well and core logs, outcrop examinations, underground observations, and mine maps. Strata exposures from both outcrops and quarries were used to construct geologic maps, stereo net, and rose diagram projections so that the Loyalhanna’s structural environment could be understood better. Many of these structural conditions cause ground control problems at local quarries. These problems ranged from small-to-moderate sized rock falls associated with roof jointing to pillar failures associated with dipping discontinuities. Stresses ranged from tensional on structural domes where weathering dominates, to high levels of compression within structural saddles. A greater understanding of these characteristics is a prerequisite to develop engineering controls, such as improved mine layouts, pillar sizes, etc., that lessen miner exposure to these hazards.

By V. A. Leach, J. R. Johnson

The calculation of the dose to the bronchial epithelium, lungs and other body tissues from exposures to airborne radon and thoron daughters requires a knowledge of the pattern of deposition in the respiratory system and clearance from it. Exposure to radon or thoron daughters is measured in units of Working Level Months (WLM), which is independent of the aerosol particle size, the fraction of daughters that are attached to the aerosol and the degree of disequilibria between the daughters, and age and breathing rate of the subject. These factors will influence the deposition and clearance, and hence dose. It is therefore of interest to find the relationship between WLM and calculated dose as a function of aerosol size, unattached fraction, and disequilibria, and of age and breathing rate, and to define ranges for these parameters for which WLM is an acceptable measure of the risk. This presentation briefly reviews the two dosimetry models being considered by a current Nuclear Energy Agency (OECD) Working Group, and using these models, defines limits on parameters for which the WLM is applicable.

Jan 1, 1981

THE following brief paper is submitted with a view to encouraging the exploitation of hitherto neglected 10w~ grade ore-bodies which are suitable for extraction by open-cut methods.The Corinthian North mine, situated 10 miles from Southern Cross, in the Yilgarn district of Western Australia, furnishes an example of low working costs, although operations are carried out on quite a limited scale.The body of quartz which is now being worked strikes N.W. and S.E., has a very slight underlie to the west, and lies between bodies of quartz-hrematite s,chist on the east and amphibolite on the west.So far as the property has been explored, it would appear that the underlying sulphide rises to within about 70 ft. of the surface in the northern end of the workings, and pitches away to the south at a grade...

Jan 1, 1915

By M. Katzer

The effect of selective dispersants as wet grinding aids for ores is demonstrated on laboratory scale batch and continuous grinding equipment. A complete characterization of behavior is performed on a given ore to demonstrate correlations involving torque, % solids, net production rate, and slurry weight and volume loading. The relationship between such laboratory data and industrial scale testing results is very consistent.

Jan 1, 1979

A numerical method for discriminating between replacement and sedimentary processes is applied to a folded stratiform sulphide occurrence. It is shown that numerical treatment of chemical analyses from a single diamond drill hole allowed a rapid assignment of the ore to the syngenetic sedimentary class and thereby enabled a revision of the evaluation program concerned with consequent reduction in costs.

Jan 1, 1973

By Kramadibrata S

Over the years many attempts have been made to develop a means of assessing the excavatability of rock. Most of them are based on an empirical rating system while some authorities still propose the use of seismic velocity as a direct predictor of the rippability of a rock mass. On the other hand there are a number of classical models which have been developed to define the cutting force required at the pick or tooth of continuous miners.While these methods have been applied with various degrees of success to the design of excavation systems there is no generally acceptable method of defining the excavatability or cuttability of a rock mass in terms of the machine power required to generate a particular rate of production.The authors have attempted to overcome this deficiency by recording the intact and rock mass properties at a number of surface mines where continuous miners were in use and to use this data to examine the relationships between the relevant dimensionless groups developed from a dimensional analysis of the problem.The results obtained are encouraging and it appears that this new approach to the problem could lead to civil and mining engineers having a means of predicting the cutting power required to excavate rock at a given rate at any site.While this paper does not include a review of past work it refers to a number of key publications which will give the reader an excellent introduction to the subject.It is important to point out that the research work reported in this paper is part of a doctoral research project at Curtin University of Technology on the Influence of Intact Rock and Rock Mass Properties on the Design of Surface Mines. One of the major objectives of this project is to explore the possibility of developing a technique for predicting the excavatability of rock in surface mines at the design stage.This paper therefore commences with a brief reference to the continuous surface miners in use at the test sites followed by some original work by the authors in applying Dimensional Analysis to analyse the macro-performance of mechanical excavators. Following an analysis of the experimental data the authors validate the wider use of the model by referring to its successful application in predicting the power required to excavate rock by continuous surface miners at other sites.

Jan 1, 1995

By W. E. Halle, G. J. S. Govett

"The Institute of Applied Geology, Manila, Philippines, is jointly sponsored by the University of the Philippines, the Philippines Bureau of Mines and the United Nations Development Programme (Special Fund). It provides, in its fourth year of operation, an interesting example of international cooperation in mineral development. Objectives include: (1) the training of mining engineers in modern techniques of mineral exploration; (2) assisting government and industry in discovering new ore deposits; and (3) providing the basis for the establishment of an economically oriented graduate school of geology at the University, the first of its kind in the country. Training of engineers requires roughly one full year, which is divided between academic study and actual field practice. Lecture and laboratory instruction include courses at university level designed specifically to up-grade those aspects of the geological sciences that are required by mining engineers now qualifying as mineral exploration engineers-economic geology, applied geochemistry, geo-physical exploration, petrology and structural geology. The field training involves direct participation in actual mineral exploration projects arranged with the co-operation of the Bureau of Mines and private interests engaged in mineral development and production. The system works well in practice, and the Institute staff and trainees were responsible for outlining new evidence of economic mineralization. It is also apparent from the application of the exploration methods available to the project -geological mapping, air photo interpretation, magnetic, electric, electromagnetic, self potential and gravity surveying as well as geochemical prospecting -that, under the humid, tropical, mountainous conditions in which the practical program was conducted, air-supported geochemical prospecting with attendant reconnaissance geological mapping affords the most economical and effective approach to mineral exploration for at least some of the deposits characteristic of the region."

Jan 1, 1968