Search Documents

By Kaige Zheng, Hongwei Wang, Tong Wang, Yanjun Li, Yongping Wu, JIANQIANG JIAO, Baolin Jiang

Due to the influence of economic development on the demand growth of coal resources, many mines in China have gradually entered deep mining. When the roof of deep coal seam is hard rock, it is easy to cause strong ground pressure with the advance of the working face, which seriously threatens the safety of coal mining. Taking 31,104 working face of a mine as the engineering background, this paper studies and compares the deformation characteristics and stress transfer evolution law before and after the presplitting of the hard roof through the combination of physical similarity simulation, numerical calculation, and field measurement, based on the analysis of the interaction relationship between the breaking and collapse of the composite hard roof, and verifies the treatment effect of hydraulic presplitting through field measurement. The results show that: (1) In the early stage of mining under the composite hard roof, the lower roof is mainly subjected to tensile failure, the voussoir beam structure formed is relatively unstable, and the stope is prone to impact. When the mining distance of the working face is large, the breaking rotation of the upper hard roof voussoir beam causes pressure damage to the lower hard roof, causing the lower hard roof voussoir beam structure to slide and lose stability, resulting in strong ground pressure in the working face. (2) After presplitting of composite hard rock stratum, in the early stage of mining, the range and degree of rock stratum damaged by presplitting are small except for the hard rock stratum itself, and the presplitting effect is not significant. When mining to the first square position, the roof is damaged in advance by presplitting, the overall plastic damage range increases, the damage form area increases, and the damage degree deepens. The vertical displacement of the composite hard roof increases rapidly, and the presplitting effect is remarkable. (3) The evolution characteristics of roof principal stress transfer show that under the dual effects of mining and presplitting, the roof tensile stress area above the goaf is large, the rock failure horizon rises, and the roof failure height is high and the failure degree is deep. The stress concentration degree of the coal mass in front of the goaf is reduced, and the stress concentration range is transferred to the rock mass in front. With the advance of mining, the hard roof in front can break and caving in time, so as to avoid rock burst disaster caused by large suspended roof area. The field ground pressure monitoring shows that the average periodic weighting interval, weighting range, peak value before weighting, and peak value during weighting of the working face after presplitting decrease by 53.5%, 38.03%, 8.63%, and 5.96%, respectively, which effectively reduces the weighting intensity and ensures the safe and efficient mining of the working face.

May 16, 2023

During the period 1979 thru 1982, Multi Mineral Corporation conducted a mining research program at the United States Department of the Interior's Bureau of Mines Oil Shale Mining Environmental Research Facility in the Central Piceance Creek Basin, Rio Blanco County, Colorado. The program consisted of mining, environmental and geotechnical research data and the results are described in this report.

Jan 1, 1983

By J. Kuijpers

Failure and fracturing are often regarded as synonymous. While this is obviously true in an environment dominated by tensile stresses, it is still not clear how failure and macro fracturing are related in a compressive stress environment. Excavations at great depths are typically subjected to compressive stresses only. The fracturing observed around such excavations is therefore commonly assumed to be induced by such compressive stresses. The physics of such a phenomenon have unfortunately never been explained properly, so that the formation of these so-called extension fractures still remains a mystery. As the presence of fractures is an important factor affecting the stability of underground excavations, it is of practical relevance to understand their formation. In this paper, a possible explanation is proposed. It is argued that fracturing in a compressive stress environment is a secondary effect. Primary failure, in the form of micro fracturing and associated damage is assumed to precede the major fracture processes. The fractures are thus generated in response to material failure and may not directly be the cause of failure. The implications for material response and behaviour are discussed. Keywords: micro fracturing, macro fracturing, extension fractures, failure, compressive stresses, damage, excavations.

Jan 1, 2000

By Gernot Beer, Christian Dünser, Marcos Noronha

The main findings of the joint research initiative “Numerical Simulation in Tunnelling” and a follow-on project on efficient numerical simulation models for tunnelling are presented. Die wichtigsten Resultate des Forschungsschwerpunkts „Numerische Simulation im Tunnelbau“ und einem Folgeprojekt über effiziente numerische Simulationsmethoden werden präsentiert Les résultats les plus importants du point principal de la recherche "simulation numérique dans la construction de tunnels" et un projet consécutif sur des méthodes de simulation numériques efficaces sont présentés

Jan 1, 2003

By W. D. C. MacKenzie

IT IS almost exactly fifteen years since the discovery of the Leduc oil field and, as this luncheon is part of the Thirteenth Annual Technical Meeting of the Institute's Petroleum and Natural Gas Division, it seems, therefore, a singularly appropriate time to discuss the theme which the program committee has suggested for the occasion -the progress of the Canadian oil industry during the fifteen years since the discovery of the Leduc field. As you will see, I plan to take a few minor liberties with this suggested theme. I shall present ample evidence of growth and progress, but, at the same time, I want to refer to some areas where progress has been anything but conspicuous and to see what can be learned from these areas for the future. The achievements of the Canadian oil industry since the Leduc discovery in 1947 have been substantial, and the public is relatively familiar with the more spectacular developments.

Jan 1, 1962

It is a pleasure and a privilege to be with you for the Annual Conference of The Australasian Institute of Mining and Metallurgy.The inaugural meeting of The Institute was held in Adelaide in April, 1893. Through the kindness of your President, who passed on to me several publications concerning The Institutute I have been able to glance back over the eighty years in which The Institute has served both the profession and Australia.In that record, many names of great distinction caught my eyes. When one reads the list of past presidents of the The Institute since 1893 and the list of those to whom The Institute Medal has been awarded, one reads the headings of a biographical dictionary of the Australian mineral industries. Many famous names are there-men from the great mining companies, engineers, scientists, metallurgists and geologists. Simply to read the names is to recall great enterprise and great achievement. Going over those names one hears the echoes of the inspiring story of the establishment of the Australian steel industry, the electrolytic zinc inq.ustry, all the major developments in the mining of coal, gold, copper, silver and lead, the treatment of difficult ores, the geological exploration of a cqntinent, the discovery of uranium, bauxite, petroleum, nickel, the establishment of the alumina industry and finally the mammoth earthmoving operations of today. The list of names is a chronicle of great men who did a mighty work. They stand like milestones in the progress of a nation.When one reads further and runs down the titles of some of the papers published in the Proceedings of The Institute even a layman like myself can appreciate the dramatic developments in mining and metallurgy that have transformed the whole practice of the mineral industries in our land. Australians have made some notable innovations and discoveries both in mining techniques and in the processing of ores. The history of mining is not only a story of the discovery of the mineral resources of this continent but of adventurous steps taken to perfect new ways of mining the ore and extracting the metal.I read with great admiration the presidential address given by Sir Maurice Mawby in 1968 and wa...

Jan 1, 1973

By R. F. Rolsten

VAN Arkel 1 prepared ductile tantalum by the thermal decompoiition of tantalum pentachloride on a resistively heated wire (2000° C) in an evacuated bulb maintained at 100°C. Burgers and Basart2'3 observed the formation of a mixture of tantalum carbide and free metal when a carbon deposition base was used. campbel14 suggested the thermal decomposition of the iodide if a lower decomposition tem- perature was desired. To date, the details for preparing high-purity iodide tantalum have not been disclosed. EXPERIMENTAL The tantalum to be purified was symmetrically placed around the clear quartz deposition surface centrally located within a 64 mm cylindrical Vycor bulb. The deposition vessel usually employed5 was modified6 by incorporating a reentrant fin,mer in place of the customary metal filament in the head

Jan 1, 1960

By H. Merton Ruth

THE northern anthracite fields, although facing the same economic problems as the southern fields, are confronted with the additional problem of fast dwindling reserves of anthracite which can be conventionally and economically won. The mining of coal which remains in thin beds and the recovery of pillars from areas heretofore considered unrecoverable, either by reason of cost or surface restriction, pose problems of in- creasing importance to the economic life of the northern field operations. Successful approaches have Been made to this problem and other work is being performed that holds promise. There exists in the northern anthracite field millions of tons of solid coal, the recovery of which has not been too successful due to the following inherent operating faults: inability to concentrate producing areas; the great quantities of rock to be cut and handled, lack of consideration of proper sequence and speed of second mining, and the continued use of the mine car as the basis of payment. A mining system that has successfully solved these major problems has been in operation in the Scranton area since 1944. Over 1% million tons have been produced from veins varying from 3 to 4% ft thick by this method, which is known as the multiple panel-triangular system-conveyor mining.

Jan 1, 1950

By A. F. van Weele

In general cast-in place piles will have an irregular pile shape. However, it is possible that these irregularities are so large that they may lead to pile deficiencies. It is very rarely possible to examine the pile foundations visually. Also the performance of a static or dynamic load test on each individual pile is not practical and much too expensive. This is the reason why pile integrity tests have been developed: to reduce the risk of inadequate pile foundations by performing a simple test. Pile integrity tests are non destructive tests which are carried out after a pile has been installed. Over the years a number of techniques have been developed of which the most important techniques are briefly described in this paper. Of all pile integrity testing methods, Sonic Integrity Testing is the most widely used method in western Europe. This method has been developed by TNO some 15 years ago. Since then the method has been improved, largely due to advances in micro-processing. A major improvement was made by the introduction of digital signal processing techniques. This made the Sonic Integrity Testing method more accurate (smaller defects can be detected), faster (more than 200 piles can be tested on a single working-day) and more reliable (the results are easier to interprete). A few cases will be presented which will show the usefulness of the Sonic Integrity Testing method. In one of these cases, a helpful tool for interpretation of the results is explained: the Sonic Integrity Testing Simulation program TNOWAVE. Notwithstanding the fact that Sonic Integrity Testing is a powerful method, it has also some strict limitations. These will be discussed at the end of the paper.

Jan 1, 1987

By F. Peer

In most coal preparation processes, water is a necessary medium, but the presence of water in coal after it has been cleaned has a negative impact on transportation costs, handling and specific energy values. The utilization of super absorbent polymers (SAP) in the nappy application is well known. The concept of utilizing these polymers was investigated for the purposes of dewatering coal and other fines, generated by preparation processes such as flotation. SAPs are granular highly cross-linked synthetic copolymers with excellent water-absorbing properties. The dewatering process is characterized by three main stages: (a) contact of super absorbent polymer with high-moisture fine coal; (b) separation of dewatered fine coal from super absorbent polymer; and (c) regeneration of used super absorbent polymer, by exploiting its response to changes in conditions such as pH or temperature. Preliminary tests showed the separation step to be very difficult. The novel idea of encasing a given amount of polymer in a water permeable cloth solved this problem (of separating the swollen polymer from the dewatered coal). Preliminary tests investigating the effectiveness of the sachets of polymer showed a drastic decrease in the moisture contents of slurries. Furthermore, it was shown that it was possible to regenerate the polymer (still within the sachets) through thermal drying. A full-scale experimental programme was then followed to accurately determine the feasibility of using sachets of SAP. The experimental variables were initial slurry moisture content and polymer dosage. It was observed that the sachets seemed to work fastest and most effectively at high moistures and also at higher dosages of SAP. Regeneration of the polymer was also investigated, using two methods: thermal regeneration and pH-induced regeneration. The experimental variables, for investigating the regeneration process, were method of regeneration and grade of water used. Thermal regeneration at 70°C seemed to work successfully. Although the cost of using thermal energy is still a problem, the safety aspect (fire hazards) has been addressed since the polymer does not ignite when heated, unlike fine coal particles that may do so. The alternative method of regeneration, which exploits the pH-sensitivity of the polymer, was less successful, and further work needs to be conducted.

Jan 1, 2003

By R. A., Pallanch

THOUGH the flotation of gold ores has come into the lime- light largely in recent years, it is not a product of recent economic conditions but rather as old as flotation itself. It could hardly be other- wise, since gold, when in the right state of comminution and surface condition, is one of the more readily floated of minerals. In early practice it was not generally recognized that gold was floated as well; it was - thought that the gold was bound up with sulphide minerals that floated, but now we know that free gold must have been floated as well.

Jan 1, 1935

Minerals are vital to any industrialized civilization. Annually, the United States uses more than 4 billion tons of new mineral materials, or about 40,000 pounds per person-about half being mineral fuels and the other half being metals and nonmetallics. Stable and economic domestic mining, mineral, metal, and mineral reclamation industries are essential to the economy. The value of United States energy and processed materials of mineral origin exceds $200 billion annually. Although a number of minerals are imported, especially some designated as "strategic and critical," most U.S. mineral supplies are derived from the domestic mines and processing facilities that you will be seeing, reading about, and visiting as you use this visitor guide. We hope you enjoy your experiences. This pamphlet, a guide to mining and mineral operations that may be observed or visited and some other points of interest relating to minerals, is intended to aid tourists and students who are interested in mining. Some may wish to study our Nation's romantic past; others may plan to enter the minerals industry as a career; still others may have a primary interest in conservation practices. The pamphlet is also intended to aid State and local officials, Chambers of Commerce, and mining firms in answering some of the many questions of tourists and students.

Jan 1, 1976

By William Gleason

The mining industry is a unique space. It is one in which geologists and chemists can intersect with computer and data science professionals daily. The industry requires expertise in not just mining and metallurgical engineering, but also electrical, mechanical, environmental and more. It requires expertise in worker health and safety, behavioral science, finance and economics, as well as human resources management. The locations of mining operations are often in remote corners, and for underground activities, they are unlike anything else in the world. The industry presents those who join it a wealth of opportunities, but often struggles to overcome incorrect perceptions of safety, labor and environmental standards, making it difficult to recruit and retain employees at a time of increased demand for mined materials.

Dec 1, 2025

By Michael J. Beus

The National Institute of Occupational Safety and Health-Spokane Research Laboratory (NIOSH-SRL) have developed a Shaft Conveyance Monitoring System (SCMS). Assessment of current hoisting technology has shown that monitoring wire rope tension and conveyance position and load directly from the skip or cage top offers several significant safety, production, and maintenance advantages. The SCMS consists of conveyance position and guide displacement sensors, a battery power supply and charging system, and a new sensor to measure hoist rope tension. This device provides a warning of the occurrence of ?slack rope? a particularly dangerous condition. A 2.4 GHz radio link transmits data to the hoistroom. A reduced scale hoisting test facility has been constructed to test these components prior to field trials. The advantages of monitoring wire rope tension and conveyance position and load directly from a skip or cage top will be discussed. Field tests are underway in full-size shafts to refine the concept and evaluate long-term reliability and maintenance requirements. Application of this technology may result in decreased maintenance costs as well as safer, more productive hoisting operations.

May 1, 2001

By J. Evans

Including: Tailings thickeners, CCD?s, paste thickeners, HI-rate thickeners, lamella thickeners, high compression thickeners, clarifiers etc. Flocculant dosing control for mining thickeners and clarifiers is influenced by a number of process factors. 1. Flow rate into the thickener or clarifier a) As the flow rate increases into the thickener or clarifier ?retention time? decreases which causes a greater affect hydraulically on the settling solids. So as the flow rate increases it will generally mean an increase in flocculant dosing rate. b) As the flow rate decreases into the thickener or clarifier the retention time increases which reduces the hydraulic affect on settling, improving settling rates. This will generally mean that as the flow rate decreases, we will decrease the flocculant dose rate.

Jan 1, 2011

By R. Snoby

Since its introduction in 2002, the modern air jig has processed a wide array of coals throughout the world. This paper explores the reasons and justifications for the installations and provides case history performance data. Specifically highlighted are air jig plants processing metallurgical coal in Colombia, bituminous coal in the United States and India and lignite in the United States and Spain. Each installation has unique reasons to justify an air jig facility. It is important to note that not all of the justifications were based on the ?most cost effective yield?, normally a mantra for coal preparation plant designers and owners. Dry jigging of coal has long been a proven technique for upgrading coal, the modern air jig, with its improved efficiency and operating systems simply extended the range of applications. In some cases, it even allows market quality coal to be produced when no other option is possible.

Jan 1, 2009

By W. J. Wright

Summary This paper describes the general situation of the mining industry in New Brunswick, and gives a detailed description of the recent developments in the antimony deposits at Lake George and the copper deposits in the vicinity of New Horton. At the end are lists of the most interesting geological literature relating to the Province and of the geological and topographic maps that have been published. Introduction In presenting this paper to the Institute, I apologize for the small amount of scientific data which it contains. Recent investigations in the Province of New Brunswick have been carried on largely by outside interests, and at present we ourselves are in the position .of taking stock. However, I am glad of the opportunity of giving you a general idea of the situation. The Province is making an honest effort to learn the truth concerning her mineral deposits and in time hopes to collect data which should be of interest to the mining community.

Jan 1, 1931

By D. M. Clippinger, J. J. Eidel, J. E. Frost

At Ithaca Peak, one of three peaks situated on Duval Corporation's Mineral Park property, a 'Single pulse of quartz monzonite magma intruded the isoclinally folded Precambrian Cerbat complex consisting of schist, quartzfeldspar gneiss, and amphibolite. The magma reacted with the Precambrian rocks, yielding a quartz-diorite rim. As the magma crystallized within the rim, it produced, progressing in'ward, annular bodies of quartz monzonite porphyry, quartz porphyry, and a distinctive quartz porphyry containing abundant podiform, tabular, and irregular quartz masses. These quartz masses are spatially associated with discontinuous crenulate and tabular quartz veinlets. Following crystallization, the Ithaca Peak stock and part of the surrounding Cerbat complex were fractured, producing a stockwork of predominantly northwest and northeast-trending fractures. The stockwork was then mineralized during a period of decreasing temperature by: ( 1) quartz-pyritechalcopyrite veinlets without distinct selvages and with distinct alteration envelopes in which orthoclase was altered to quartz and sericite; (2) quartz-pyrite-chalcopyrite veins and veinlets with distinct selvages and without distinct alteration envelopes; and (3) pyrite-chalcopyrite- galena-sphalerite veins. The Ithaca Peak stock was pervasively sericitized or argillized. The Mineral Park property is surrounded by a zone of propylitization Alteration and mineralization are coextensive in space and were, at least in part, coincident in time. The Mineral Park property possibly was elevated and exposed twice prior to its present exposure. The protore has been enriched by a factor of three. The Ithaca Peak supergene ore body is conformable with present topography and lies above the present water table. The shape of the ore body was controlled by erosion and oxidation of the previously enriched mineralization. Hematite, goethite, and jarosite present at the surface indicate a high primary pyrite environment, but it is possible to recognize that a small proportion of veins and veinlets contained greater amounts of chalcocite and chalcopyrite than pyrite. The igneous facies on Ithaca Peak are the products of differentiation within a solidifying rim according to Bowen's Reaction series. The innermost facies contain more quartz and orthoclase than the outer facies. Late magmatic quartz in the case of Ithaca Peak contains small amounts of pyrite and molybdenite. It is suggested that this quartz-sulfide mineralization, may also have been the product of differentiation the product of differentiation, may indicate that the later hydrothermal mineralization may also have been the product of differentiation.

Jan 1, 1968

By F. Louis Grammer

The following study of flue-dirt and the influences controlling it may be interesting to many. It is published because it represents observations at about thirty furnaces at different times. It may assist in giving an impetus to the making of similar observations elsewhere. Until ten years ago, the metallic waste in furnace-gases was not considered a problem of pressing urgency in iron metallurgy—certainly not in the blastfurnace end of it. Many plants at present ignore, or pay but little attention to, top-pressures. Prior to the introduction of Mesabi ore, the losses in escaping gases, if considered at all, were regarded as thermal losses, or losses of fuel (except by those interested in lead, zinc, silver, etc.). In a high-priced material like ferro-manganese, such losses were, indeed, considered important. But the behavior of the Mesabi ores, corning, as they did, in practically inexhaustible quantities, could not be disregarded by the furnaceman. These ores came to stay. The tables appended below have purposely been altered to disguise the plant, the company and the ores used. The comparative values are maintained. In these tables, the influencing elements and conditions which are constant, or practically so, namely, size of furnace, quantity of wind, fuel used, etc., are not mentioned. The figures represent observations consistently followed up for a long period. The weights of flue-dirt were obtained from cars on which no other dirt was thrown. The analyses and calculations are based on the best of sampling. The effects of slips are excluded. Slips should not occur at well-regulated or properly-constructed furnaces, excepting under unusual and rare conditions. Allowances are made for moisture, scrap charged and silicon in the metal. The cutting effect of Mesabi

Jan 1, 1904

By Scott C. Vollmer

This paper seeks to examine some of the technical factors influencing the deflection of Mechanically Stabilized Earth (MSE) retaining walls based on the authors' field observation of numerous structures. Excessive deflections can be unsightly and can be perceived as wall failure. Deflections can cause cracking or gapping of the facing units and general misalignment. Deflection of the reinforced backfill zone behind the wall face can result in settlement of the backfill zone and adjacent pavement cracking. Deflections can be the result of excessive movement external or internal to the reinforced soil structure. This paper only examines internal factors affecting wall deflections. External factors such as foundation settlement are not discussed.

Jan 1, 2003