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By H. Habenicht

Requirements for full extraction in underground coal mining call for inexpensive, safe, techniques to be competitive with conventional methods. Longwall and shortwall systems are to some extent employed for this purpose. Another method would be rib pillar extraction (and pillar extraction). These methods are compared with each other with respect to procedure, equipment, safety, roof control, investment, output, performance, costs The advantages of r.p.e. show this method very attractive. Number and cost of equipment are lowest. Safety and roof control becomes improved by a mobile roof support recently developed in Austria. Its successful use in the R.S.A. is being explained.

Jan 1, 1986

By H. Habenicht, E. Urschitz

Three mining methods for full extraction in flat coal seams - i.e., longwall (L W), shortwall (SW), and rib pillar extraction (RPE) - are com- pared with each other in view of the introduction of a mechanized, self-advancing roof support. Features are shown according to which RPE appears most attractive under certain conditions. In this presentation, the mining methods are outlined and discussed. The new support (Alpine Breaker Line Support, ABLS) is described, and its employment is explained. A trial operation in RPE using the ABLS has been conducted successfully in a South African coal mine. The results and improvements are stated.

Jan 1, 1988

By Jon Bowler

Daw Mill Colliery, UK Coal, near Coventry in England, mines the Warwickshire Thick Seam at 800 m/2500 ft depth using longwall retreat with gateroads supported by rockbolts. Over the last eight years the mine has worked longer and wider panels with extraction heights of over 5 m. Recently the mine has experienced high deformation conditions principally from the rib sides resulting in operational issues and production delays. Investigation of rib deformation was undertaken using new inspection and measurement techniques, including systematic laser surveying, and improved rib support consumables were developed and introduced. A new rib trussing system using textile webbing has proved very successful.. A rib support management system was also developed and introduced for face retreat. This allowed rib support to be more effectively managed both for production and safety. For the current developments, new 28-mm-diameter roof and rib bolt systems have been introduced and rib bolt length has been increased to 3 m, with the aim of achieving gateroad stability over the life of the panel. Significant reductions in roof and rib deformation have been confirmed by the latest monitoring results. These ground control innovations are allowing Daw Mill?s potential to be realised. Production from 302?s face in 2008 set new UK and European records. However the support enhancement process continues and further innovations are planned.

Jan 1, 2009

By Jon Bowler

Daw Mill Colliery, UK Coal, near Coventry in England, mines the Warwickshire Thick Seam at 800 m/2500 ft depth using longwall retreat with gateroads supported by rockbolts. Over the last eight years the mine has worked longer and wider panels with extraction heights of over 5 m. Recently the mine has experienced high deformation conditions principally from the rib sides resulting in operational issues and production delays. Investigation of rib deformation was undertaken using new inspection and measurement techniques, including systematic laser surveying, and improved rib support consumables were developed and introduced. A new rib trussing system using textile webbing has proved very successful.. A rib support management system was also developed and introduced for face retreat. This allowed rib support to be more effectively managed both for production and safety. For the current developments, new 28-mm-diameter roof and rib bolt systems have been introduced and rib bolt length has been increased to 3 m, with the aim of achieving gateroad stability over the life of the panel. Significant reductions in roof and rib deformation have been confirmed by the latest monitoring results. These ground control innovations are allowing Daw Mill?s potential to be realised. Production from 302?s face in 2008 set new UK and European records. However the support enhancement process continues and further innovations are planned.

Jan 1, 2009

The National Institute for Occupational Safety and Health (NIOSH) conducted a monitoring field study to optimize the rib control plan in a room-and-pillar coal mine. The study mine is located in the Central Appalachia coal basin. Two monitoring sites were selected at different sections in the study mine. The selected sites have different overburden depths and geologies. The instrumentation plans at study sites include borehole pressure cells installed at various depths in studied pillars, rib and roof extensometers and load cells mounted on number of the rib bolts. The instrumentation results and observed geology for one of the study sites showed great potential for optimizing the rib bolt plan at that section of the mine. Therefore, a rib support optimization study was followed using numerical modeling technique. A calibrated threedimensional model was developed using the instrumentation results of the optimization section. The calibrated model was used to determine the optimum rib support for expected overburden depths and rib heights. Baseline rib bolt patterns were assumed for the optimization study. Additional rib bolts, above and beyond the baseline bolting parameters, were outlined and identified as solutions to contain the rib fracturing identified by the modeling results.

Jul 28, 2020

By J. J. S. de Beer, F. Hunter, A. F. Neethling

SYNOPSIS The paper describes the rib-pillar extraction method now used at Sigma Colliery in the Orange Free State. In this method, access roadways (with a high safety factor) are developed into a block of coal suitable for total extraction; pillars that have a low safety factor are then formed and extracted immediately. The method, together with the current practices of labour management, has resulted in better utilization of the coal resources and capital, increased production and labour productivity, and improved safety.

Jan 1, 1991

By Erik Melchiorre, M. Katherine Crombie, Dante Lauretta, Chris Gholson

Rich Hill, also known as Weaver District No. 2, is among the most productive placer gold locations in Arizona. Located near Congress, AZ (Fig. 1), this district hosted major placer rushes in the 1860s and1930s. Those rushes were followed by an electronic metal detecting rush that started in the 1980s and continues today. Thousands of ounces of gold have been produced by these modern amateur and professional metal detectorists. Many of them see more gold in an afternoon than Nevada mine workers will ever see outside of the mill. Rich Hill discovery Inspired northeastward by Spanish legends, a party of 10 men left Yuma, AZ on April 1, 1863. Included in the group were Pauline Weaver (Fig. 2), Henry Wickenburg and Abraham Peeples. Wickenburg left the group near the Hassayampa River and discovered the Vulture deposit. The rest of the group arrived at the base of Rich Hill in late May. While drying antelope meat on the first day, a few of the men prospected a nearby creek bed and immediately found gold. In a couple of hours they picked up more than 2.8 kg (90 oz) of gold. The next day, four members of the party went searching for their horses and returned with news that a nearby hilltop was literally graveled with nuggets.

Jan 1, 2003

By AIME

TITANIUM-RICH ilmenite deposits, situated in the Allard Lake area in Quebec some 400 miles down the St. Lawrence River from Quebec City and 28 miles north of Havre St. Pierre on the north shore of the Gulf of St. Lawrence, are undergoing an intensive development program by the joint efforts of the Kennecott Copper Corp. and The New Jersey Zinc Co. Easily accessible ore, amounting to about 125 million long tons and carrying from thirty to forty per cent titanium oxide, has been delimited. Plans are being made for construction of an electric smelter at Sorel, on the south bank of the St. Lawrence midway beween Montreal and Three Rivers, which will produce 650 long tons of high-grade titanium slag and 500 long tons of iron per day from 1500 long tons of ore. Occurrence of ilmenite ore in this area has been known since J. A. Retty reported his geological work in the lower Romaine River area for the Quebec Bureau of Mines in 1941. In this report Dr. Retty mentions the presence of anorthosite rocks, some of which were rich in ilmenite. Claims were staked by several interests but the small showings and complex metallurgy were too formidable for any organization not adequately equipped with capital, metallurgical knowhow, and market outlets. However, Kennecott became interested and through a newly formed Canadian subsidiary, Kennco Explorations Ltd., options were taken up under the direction of A. H. Robertson. An area of 300 square miles was traversed in the summers of 1945 and 1946. During 1946 and 1947 geophysical and diamond-drill prospecting disclosed a num-

Jan 1, 1948

By M. B. Dunn

Terminals form part of the transportation chain from producer to consumer in the world-wide conveyance of bulk commodities. As such, they are a vital link in providing a buffer between widely differing transporation modes. It is essential in the conceptual design of such terminals that an overall view of the entire system of which they form a part is taken. Only in this way can it be ensured that the system will operate smoothly and without disruption, for in the end such disruptions can have dramatic repercussions, both on the cost of the commodity in the market place and on production. In this respect, computer simulation is a useful tool in arriving at the optimum design for the system. The Richards Bay Coal Terminal provides a good example of such an approach. Commissioned in 1976 to handle 12 Mt per annum, it is now handling 24 Mt per annum, with plans for further expansion to 44 Mt per annum in the future.

Jan 1, 1980

Jan 1, 1902

By George L. Heath

This paper is devoted chiefly to the coal-fields of the western part of the province of Chili and the eastern part of the province of Shansi; but the outline of this belt will give some idea of the extension of the coal-fields over northeastern China. This part of China is topographically divided into: (1) the mountainous peninsula of eastern Shantung; (2) the coastal plains, extending W. and SW. from the gulf of Pechili; and (3) the mountains and table-lands N. and W. of the coastal plains. The plains extend N. and W. from the gulf to within from 10 to 25 miles of the Great Wall, while their SW. extension covers western Shantung and reaches W. along the Yellow river almost to the southern boundary of Shansi. A line joining the mapped coal-fields, shown in Fig. 1, almost gives the western boundary of the plains; since these areas lie on the border of the plains—except the Tsê Chou field, which is on the table-land, 20 to 25 miles from that border. The coal-fields which have been mapped and investigated by the author are shown in Fig. 1. The one at and around Tongshan is known as the K'ai-p'ing coal-field; the one W. of Peking has been called the Wang-p'ing coal-basin; the one SW. of Pao-ting and N. of Chêng-ting may be called the Lingshan coal-field; and the one at and around Tsê Chou is known as the Tsê Chou coal-field. I. The K'ai-p'ing Coal-Field. As is shown in Fig. 2, most of this field lies in the coastal plains, and is therefore covered by alluvium and loess, which have buried the older rock-beds, and the more gentle and older topographic outlines, to such an extent that most of the re-

Jan 1, 1902

By George W. Sargent

For the experiments here described a rod was used, 0.75 in. in diameter, and rolled from one ingot. Analyses of the ingot and rod showed them to have the following composition respectively: C. Mu. Si. P. 8. Percent. Percent. Percent. Percent. Percent. Ingot,. .. 1.150 0.328 0.223 0.020 0.016 Rod,. .. 1.033 0.327 0.223 0.020 0.016 Pieces 4 in. long were heated to various temperatures in a closed porcelain tube, within a gas furnace, and allowed to cool with the same; they were then turned, threaded, and subjected to physical tests in a Riehlé testing-machine. The elastic limit was determined by the drop of the beam. The elongation was measured in two inches. From the threaded ends of the testrpieces, disks were cut, and prepared by combined polishing and etching, using parchment stretched over a wooden block and moistened with a 2-per cent. solution of ammonium nitrate. The structure, as thus developed, and the fractures, were magnified and photographed. A cooling-curve was constructed, and the critical point was located at 675º-680º C. A thermo-electric pyrometer was used to make the measurements of temperature. The micro-constituents of steel have been so frequently and thoroughly described by others that I need only say here that the theoretical micro-structural constituents of this steel were : pearlite, 95 ; ferrite, 0 ; cementite, 5 per cent. The quenched metal would be expected to consist almost entirely of martensite—provided, however, the quenching be done at or near the proper temperature. Rapid quenching from a high temperature would give rise to austenite.

Jan 1, 1902

By William Glenn

Early in the last century, Isaac Tyson, Jr., of Baltimore, was a miner of ores of chromium, iron and copper, and a manufacturer of their products. He was first to erect in America, for the reduction of copper-ore, a German blast-furnace, which was copied largely, and the improved successors of which are now universally used in this country. Dying in 1862, he left his manufacture of alkali bichromates to his eldest son, Jesse, while his work in the departments of mining and smelting descended to his second son, James Wood Tyson, the subject of this notice. The father had mined chrome-ores in Maryland and Pennsylvania and manufactured their products at Baltimore; he had mined and reduced copper-ores in both these States; iron-ores at Tyson Furnace in SW. Vermont, and copper-ores in the northern and central parts of that State. Among his holdings was what later became the Ely mine, now called Copperfield. The son extended this work to central Georgia, and carried the family mining interests to the Pacific coast, where he took up chrome-mines in Oregon and elsewhere, as far south as southern California. On December 3, 1900, in the 73d year of his age, James Wood Tyson passed away, in his native city of Baltimore, charging his third son, James Wood Tysou, Jr., with the labors which, 38 years before, his father had resigned to him. Thus was the work of father and son in mining and metallurgy, continuing without interruption through almost

Jan 1, 1902

By R. W. Raymond

Samson Jordan was born at Geneva, Switzerland, June 23, 1831. At the age of 20 years he entered the Ecole Centrale des Arts et Manufactures, at Paris, from which he was graduated with high honors in 1854. After some months of service with the Compagnie du Chemin de Fer du Nord, he was employed (upon the recommendation of his former instructor, Prof. Burat, who had recognized his remarkable ability) at the mines of Portes, belonging to the Société de l'Elairage au Gaz et des Hauts Fourneaux, etc., of Marseilles, and subsequently to construct the St. Louis iron blast-furnaces of that Co. After finishing this work, he remained at Marseilles as a member of the directory of the Co., particularly connected with the development of its mines. In 1862 he became the general advisory engineer of the Co., and still later (1873) its general manager (Administratet~r), a position which he retained until his death, February 24, 1900. He became subsequently Administrateur of other important French industrial enterprises, including those of the Compagnie des Naut Fourneaux, Forges et Aciéries de Denain et Anzin, and the Compagnie Banco-Belge des Mines de Somorrostro ; and he was also, at various times, President of the Société technique du Gaz, Vice-President of the Comité des Forges de France, mepber of the Council of the Société d'Encouragement pour l'Industrie nationale. In all these positions, it is the unanimous testimony of his colleagues that he was no mere ornamental figurehead, but a profoundly wise, practical and industrious laborer and adviser, both patient and keen in the mastery of details, yet at the same time competent to apprehend the wider bear-

Jan 1, 1902

By William Glenn

That basic slag will rapidly destroy ordinary (i.e., siliceous) fire-bricks is known to every smelter; and the smelter of copper-ores in particular knows that any kind of slag occurring in his practice is destructive. From this fact arises the chief distress of those who attempt to smelt copper-ores in any manner of furnace constructed of bricks or stone, or other similar material. We have passed the fire-brick stage of our experience; and now, having entered upon the period of the water-jacketed cupola, we will employ no furnace other than that having steel walls, kept cool by water. But,, unfortunately, the bottom of a water-jacketed cupola, kept cool by another water-jacket, fails of its purpose, being thereby made so cold as to chill both slag and regulus to a degree not bearable. The situation is more or less ameliorated when the upper surface of the water-jacketed bottom is covered with fire-bricks, since, so long as they last, they prevent the molten material from contact with the cold bottom. My own observation leads me to suppose that most smelters construct cupola-bottoms of iron slabs, which are covered, to a greater or less depth, with fire-bricks. There are cupola-bottoms which

Jan 1, 1902

By Otto F. Pfordte

The great advance of the last twenty years in the specialization, delicacy and efficiency of ore-concentrating apparatus calls for a finer system of testing both the qualities of ores and the operations of machines in this department. In amalgamation, lixiviation and smelting, the daily employment of physical and chemical tests has been recognized as necessary, and the cost of the necessary laboratories and employees is cheerfully paid. But while much progress has been made in concentration (due, in a large degree, to the study of the subject in our technical schools), it is still too common in actual practice to follow the loose old method of roughly estimating, once for all, that a given ore " concentrates x tons into one," and resting on this assumption so long as that ore continues to be treated, while assays of the tailings from concentration are made from time to time, without exact determination of their quantity. The first step toward accuracy of control must be a more frequent and precise measurement of the quantity of concentrates from a given operation. This should be expressed in pounds per unit of one ton; and the variations shown in frequent determinations will furnish a constant check upon the character of the ore and the performance of the apparatus. But this is only a part of what should be constantly and systematically done to insure the best work upon a material which must vary continually, even though it come from one mine only. If, in any mill, appropriate laboratory-tests were made at least once a week, the labor and expense involved would be amply repaid by increased knowledge and control of the current operations. A small testing-laboratory, provided with a few gold-pans;

Jan 1, 1902

By Robert W. Hunt

There are certain physical characteristics of steel resulting from its treatment while being formed into useful products which have been, and are, well known to its manipulators ; but under the stress of business competition and other controlling influences, all knowledge is not always given either full sway, or even full acknowledgment. Such has been the case in the making of steel rails. It is universally acknowledged that steel rails of heavy sections, made during the last tell years, have not given as good service as the rails of lighter sections produced before that time. While certain fundamental principles of steel-making have been acknowledged, their application to the steel-rail manufacture has been, if not actually denied, completely ignored.

Jan 1, 1902

By John Hays Hammond

The Transvaal comprises about 120,000 square miles (nearly • the size of the United States Territory of New Mexico). Besides the famous Witwatersrand, which will here be de scribed in detail, there are two quartz-mining districts of some importance, viz., Lydenburg and De Kaap. The Lydenburg district first attracted attention in 1876, when the alluvial deposits of that section began to be exploited. At a later period vein-rnining was started, and at the present time several companies are operating in that district. The product in 1898 of five companies, running 137 stamps, was 154,560 tons of ore, yielding 108,884 crude ounces of gold (an average of 14.09 dwt. crude gold per ton) valued at £392,378. The De Eaap gold-fields were discovered in 1884. In 1898, seven companies, running 200 stamps, produced 89,760 crude ounces of gold, valued at £314,792. I. Mining Titles in the Transvaal. The mining laws of the Tranuvaal are most excellent in char acter, and while the claims cover every square foot of land for an area of nearly 40 miles long by from 2 to 3- miles wide, there have been practically no conflicts over extra-lateral rights. Notwithstanding the change in the political status of the Transvaal likely to follow the present war, it may be coufi dently assumed that the main features of the mining law of the South African Republic will be retained, and certain op pressive featureu of monopolies, etc., bearing with special weight on the mining industry, will be abolished. The dynamite mo nopoly was one that bore most heavily on the mining industry; and, according to the Reports of the State Mining Engineer, explosives, including fuse and detonators, amounted to nearly 10 per cent. of the total working costs of the mines. Further more, it was impossible to obtain the proper quality for the most economical working, and often 80-per-cent. or 40-per-cent. gelatine had to be used- in many instances where 60-per-cent.

Jan 1, 1902

By Walter R. Crane

PAGE I. Apparatus and Methods.......... 406 1. The Magnetic Circuit...........406 2. Apparatus Employed in the Traction-Method...... 406 a. The Coils............409 b. The Pole-Pieces..........409 3. Methods of Testing Fields Produced by Different Pole.Pices.. ..409 c. Testing with a Search.Coil........410 d. Testing with Iron-Filings and Glass Tube.. .. .410 4. General Forma of Pole-Pieces.........411 e. Flat Poles............411 f. Conical Poles........... 411 g. Spherical Poles...........411 h. Chisel-Edged (Chamfered) Poles.......412 II. Magnetic Fields...........412 5. Methods of Testinq for Magnetic Permeability...... 421 i. The Rod-Method..........423 j. Method Employed in These Experiments......424 k. Difference in the Results of the Two Methods..... 425 l. The Traction-Method.........427 m. Effect of Loosening the Charge.......430 n Corrections...........432 6. Theory.............433 o. Effect of Varying Weight on Tractive Force..... 434 p. Effect of Varying Pole-Distance.......436 q. Effect of Varying Magnetization.......436 T. Effect of Varying Size.. .......437 a. Summary,........... 441 III. The Relative Magnetic Permeability of Various Minerals,. 443 The form and strength of magnetic fields have attracted much attention. especially in connection with the designing of dynamo-electric machinery—an art which has been revolution-

Jan 1, 1902

By Henry F. Collins

The following notes on the cheap milling of a soft lowgrade ore-body in the State of Chiapas, Mexico, may be of interest. The ore-body in question was worked, not by itself, but incidentally in connection with a large extraction of concentrating-ore; and one 10-stamp battery of a 30-stamp mill used for re-crushing tailings, and provided with copper-plates, was set aside for the treatment of this particular ore, of which, during a period of 17 months, 10,274 tons, of 2240 lbs. each, were handled. Description.—The ore-body collsisted of that portion of a mass of decomposed garnet-rock of igneous origin, which, near its contact with another igneous mass, composed chiefly of the mineral wollastonite in a nearly pure state, had been permeated by solutions, depositing irregularly, throughout it, quartz, chal-

Jan 1, 1902