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DURING a period extending over about the last two and a half years, the performances of various types of rock drills in use at the mining department of the Zinc Corporation have been recorded as closely as possible. The main objective was the collection of sufficient data regarding internal water-feed hammer drills, when used for the same class of work as the older type reciprocating drill, to enable a decision to be formed on the following points:(1) Whether internal water-feed, hammer drills could efficiently perform the work previously carried out by reciprocating drills without excessive repair cost to the former.(2) If so, was it good policy commercially to eliminate the reciprocating type completely, writing these off together with the accompanying spares, accessories, and solid drill steel, and replacing with internal water-feed hammer drills, with lighter fittings, and the requisite amount of hollow drill steel.(3) What were the best types and makes of hammer drill for different classes of mining work(4) What was the economic aspect of the introduction of the principle of internal water feed to every type of machine throughout the mine.Prior to the strike of workers in May, 1919, Ingersoll-Rand E47 31-in. reciprocating drills had been used for stoping and for the major portion of driving, cross-cutting, and similar work. The accompanying columns and fittings were all 4t in. The drill steel used was solid octagon. Up to 1916 these machines were also used for winzing, after which time jackhamers were more successfully employed. These latter were of the usual types, varying in weight from 40 to' 46 Ib. Ingersoll BCR 430, Holman No. 2 spool valve, Sullivan DP33,. Waugh Clipper 55. These machines were all dry head; the drill steel was hollow hexagon, shanked.

Jan 1, 1923

By Wm. J. Wright

RECORDS of crude oil in India date back for nearly 100 years, and modest attempts were made to develop the oilfields of Assam about 75 years ago. We have no record of production until 1892 when the fields near Digboi, Assam, yielded about 700 bbl. Since that time, the production of the Digboi fields has increased slowly, but steadily, and new fields have been opened at Badarpur, in Assam, and Khaur, in the Punjab, until the production in India in 1918 was about 293,700 bbl. and the possible production at the present time is approximately 300,000 bbl. per year. In the meantime, the English oil companies in India have been slowly adding to their holdings until they have taken up practically all of the promising territory that is readily accessible, and only about one-tenth of their properties has been touched by the drill. All the producing oilfields of India, and as far as we know all the prospective fields, are confined to areas underlain by rocks of Tertiary age. These rocks consist of more than 20,000 ft. of dark sandstones and shales, with the Nummulitic (Eocene) limestone at the base. In parts of Assam, the lower measures contain economic deposits of bituminous coal. In the Punjab, the upper part contains thick beds of conglomerate. Visible organic remains are rare; except in the limestone and the coal measures. In general, the hardness of the measures increases from top to bottom, but there is an alternation of relatively hard and soft beds throughout the whole series. The rocks are everywhere folded and, in some instances, severely faulted. The crests of eroded anticlines usually stand up as ranges of hills in which the individual ridges are underlain by the relatively' hard beds. Thus structural features are suggested and often clearly defined on the topographic maps.

Jan 3, 1924

'Industrial Minerals - their mining and use in New Zealand' is the theme of the 1978 Annual Conference of the New Zealand Branch of The Australasian Institute of Mining and Metallurgy. This paper describes the use of phosphate rock, sulphur and potassium chloride (potash) - three industrial minerals which have enabled the farmers of New Zealand to increase production to current levels. The growth of imports of these raw materials for the New Zealand fertiliser industry is well documented in NZ Fertiliser Statistics 1977. This is the most recent of the Ministry of Agriculture and Fisheries annual publications on this Subject prepared from the detailed returns of fertiliser manufacture and sales from each fertiliser works. There are now 12 of these works in New Zealand one of the most recently established being in Whangarie where this conference is being held. Its capacity to manufacture superphosphate will shortly be 300 000 tonnes twice that when it opened late in 1964. New grinding and manufacturing equipment comes on stream early in 1979. This paper illustrates the interdependence of two primary industries, agriculture and mining. New Zealand's economy in the foreseeable future will be based on agriculture so that our standard of living is dependent on the overseas prices and freight costs of the bulk raw materials from which our fertilisers are made. For the year ended 31 March 1978 New Zealand's total exports were $3395 million, of this total $2413 million (71%) came from the products of pastoral agriculture (wheat, wool, dairy and other animal products), $291 million from forest products and $501 (15%) from manufactured exports. Approximately half of the pastoral receipts can be attributed to the fertilisers applied at a total cost of about $200 million including subsidy.

Jan 1, 1978

By D. B. Dow

"Natural gas-gasoline is made by collecting in the liquid state the condensable hydrocarbon vapors that exist in different natural gases in varying amounts. In the richer type of natural gas the gasoline is generally recovered by compression and cooling. If exceedingly high pressure or low temperature is used, there is dissolved in the gasoline a large amount of very volatile material, which evaporates rapidly at atmospheric temperature and pressure.In the leaner type of natural gas, the gasoline vapors are selectively absorbed from the permanent gases by passing the natural gas through an absorbing oil. The gasoline is recovered by distilling the saturated oil, and as compared with ""compression"" gasoline is of high Baume' gravity and low vapor pressure. Before a volatile gasoline can be transported in tank cars, it is necessary to decrease its volatility in order to lessen the risk of fire or explosion, as well as to prevent excessive evaporation in transit. This can be accomplished either by weathering the gasoline, or by blending it with a more stable material, naphtha being commonly used in the weathering process the more volatile portions of the gasoline are allowed to evaporate and the losses in volume are very large, therefore, blending is preferable, wherever possible.It is very difficult, however, to produce by blending, in gasoline plants, a motor fuel which is equal to straight-run refinery gasoline. In order to make a blended motor fuel of a grade equal to straight-run gasoline, only a small percentage of natural gas-gasoline can be blended with the naphtha, consequently it is customary to blend the gasoline with only enough naphtha to enable It to be shipped to an oil refinery when the material is again blended to form a finished motor fuel."

Sep 1, 1921

By William Fink

Two of the aluminum-alloy systems previously studied-the alumi-num-titanium and the aluminum-chromium-exhibit a peritectic reaction at the extreme aluminum end of the diagram. Preliminary work indi-cated that the aluminum-zirconium and certain other aluminum systems were similar in this respect. The present paper, the twentieth of a series from the Aluminum Research Laboratories, reports the results of a recent investigation of equilibrium relations in aluminum-zirconium alloys of high purity, which confirm the preliminary observations. PREVIOUS INVESTIGATIONS There has been only one investigation of the aluminum end of the aluminum-zirconium system. Sykes1 prepared and studied alloys containing 0 to 70 per cent Zr. The lowering of the freezing point of aluminum by the addition of zirconium was found to be very little, if any (less than 2°C.). He placed the solid solubility of zirconium in aluminum at room temperature between 0.57 and 0.97 per cent. A few other investigators have attempted to determine the com-position of the intermetallic compounds occurring in this system. Hönigschmid2 obtained the compound ZrAl3 as a by-product during the preparation of ZrSi2. He made no attempt to prepare other aluminum-zir-conium compounds. Weiss and Newmann3 prepared an alloy by heating aluminum with a double fluoride of potassium and zirconium. When this alloy was treated consecutively with caustic soda and hydrochloric acid, there was a residue, which contained approximately 72 per cent Zr and 28 per cent Al (Zr3Al4). Marden and Rich4 prepared an alloy in the same way, treated it with caustic soda, and obtained a residue of silver-white crystals, which contained 70 per cent Zr and 30 per cent Al (Zr3Al4).

Jan 1, 1939

By Yves Fautrelle, Kader Zaidat, Hervé Combeau, Miha Zaloznik, Mohammed M'Hamdi, Bachir Saadi, Xiaodong Wang, Knut Omdal Tveito

"Numerical simulations of macrosegregation formation during horizontal solidification of a hypoeutectic Sn-Pb alloy in a rectangular cavity is presented and compared to experimental results. The experiment involves a melting phase, a holding stage at constant temperature with/without application of electromagnetic stirring, and finally solidification. We simulate all stages of the experiment and study the segregation of Pb throughout the experiment. A twophase volume averaged model is used for the numerical simulations, accounting for thermosolutal convection and assuming perfect microscopic mixing (lever rule). The influence of the melting phase and the electromagnetic stirring is studied with different cases to illustrate the consequences on the flow pattern and Pb segregation. The numerical simulations are compared to the experimental data and the impact of chemical inhomogeneities prior to solidification on macrosegregation formation is discussed.IntroductionMany extensive investigations have been performed so far on the solidification of metallic alloys. However, the melting process of metallic alloy has not attracted attention in a same manner. Nevertheless, melting of alloy may put forth peculiar effects as described in the present paper. It has been observed from a benchmark experiment [1, 2] that significant stratification might arise during the melting process of Sn-Pb alloy. That effect was put forth thanks to the analysis of the experimental temperature distribution which indicated that the convective fluid flow was almost zero. The effect was enhanced when the lead composition was higher (above 6wt.%). The present paper is aimed at confirming that the melting of an alloy containing a heavier solute may be accompanied with a stratification of the solute which exerts a stabilizing effect on the convective fluid flow. Results obtained from numerical modeling are compared with experimental data obtained from the benchmark facility."

Jan 1, 2012

By E. J. Yoder, N. B. Aughenbaugh, R. B. Johnson

Mineral aggregates experience degradation during field and laboratory compaction. Reduction in the aggregate size is accomplished by abrasion of the particle edges and fracturing of individual pieces which have become overstressed. Little is known of the factors that govern the amount of breakdown experienced for a given situation. A field study was made of the factors affecting aggregate breakdown under compaction using three carbonate aggregates of different physical properties. The preliminary results indicate that rock type, compactive effort, gradation, and thickness of compactive layer are factors which exert the greatest influence. Mineral aggregates experience a mechanical breakdown of some of the aggregate pieces into smaller fragments during any compaction process, whether in the field or laboratory. This phenomenon occurs as abrasion of the sharp edges during movement and reorientation of the particles in densifying and/or as granulation and fracturing of those pieces which have become overstressed. Two types of aggregate breakdown occur in the field. These may be classed in a general category of aggregate degradation.* One occurs during the con- * Aggregate degradation has been defined in many different ways. For this paper it is considered as any breakdown of larger particles into smaller ones, whether mechanical or chemical. struction period and is related to the densification of the aggregate body from a loose state to a relatively dense mass by heavy compaction equipment. This type is almost entirely a mechanical action. The other occurs after the construction period when the roadway has been put into use. This in-service breakdown is; a different phenomenon from the breakdown during construction in the sense that it combines mechanical with chemical changes. Time becomes an important consideration that may cause subordinate factors in construction degradation to develop into principal ones for in-service breakdown. Breakdown of aggregates in service has been extensively studied by investigators from the northwestern

Jan 1, 1962

By Frederick H. McDowell

Notwithstanding the rapidly increasing use of copper, due to the extension of its applications within the last few years, the fact of its continued steady decline in price stands prominently forward. Nor have we far to look for the cause. The opening up of the vast copper-deposits of our Western States and territories is the metallurgical event of the last five years. We must not forget, in looking at the new field, the changed conditions under which the metallurgist must work, as compared with the previous history of copper-smelting. Until quite recently, the copper-plants of the country were few in number; and the concentration of industry implied in this circumstance, allowed many practices which must be considered as inapplicable to the conditions offered at the many mines which have of late become such important factors in our copper-production. Thus the old style of smelting the ore for matte in brick furnaces, involving great expense and time in their construction, while deservedly losing repute even in its old strongholds, in comparison with water-jacketed smelters, is still in some cases adhered to. But to put up such furnaces at Western mines would be out of the question. The large and continual need of brick for relining and repairs acts as an effectual bar, when such furnaces come into competition with the light, portable, and easily managed water-jacketed smelters of improved types. It is owing to the present unusual activity, manifested in the opening up of new copper-properties and the erection of plants for working them, that any improvement in furnace-construction is of especial interest and importance. The method in which processes are copied without variation in the rapid growth of metallurgical interests, has already been strikingly exemplified in the history of

Jan 1, 1885

By Frank E. McCall, John K. Marshal, Fred Garcia

Since the advent of longwall mining systems in the United States, mine operators are increasingly relying on methane drainage techniques to supplement the ventilation system. The most commonly used technique is the vertical gob borehole. The number and spacing of vertical gob boreholes per panel is generally based on experience and underground conditions. To design a more efficient methane drainage systems, mine operators must accurately determine methane gas produced. Thus, mine operators must monitor gas flow and methane gas concentration on every vertical gob borehole on active panels at least once or twice during each 8-hr shift. As the mine grows, it is possible to have more than one operating longwall and many vertical gob boreholes. Thus, daily visits to each vertical gob borehole site can become very time consuming. During weekends when methane gas concentrations typically drop because there is no mining activity, borehole sites may not be visited. To obtain accurate gas flow data, a gob borehole monitoring system was designed and constructed by the U.S. Bureau of Mines (USBM). Gas flow, methane gas concentration, gas temperature, barometric pressure, and vacuum pressure of the exhaust fan are the parameters collected by the system. The system also includes circuitry for automatic shutdown of the exhaust fan and an alarm system before an unsafe condition is created. Telemetry components were also integrated into the system to allow for transmission of borehole data to the mine office. As a test, the system was installed and operated on a vertical gob borehole for six months. Test results indicated that intermittent measurements with hand-held instruments from vertical gob boreholes were always higher than gas flows measurements made by the gob gas analyzer system. This paper describes the system components, operational characteristics, and the results of the test program.

Jan 1, 1995

By C. L. Berrien

Before the present company was formed, in 1916, each group of mines comprising the old organizations made its detailed daily and monthly mine cost records along the lines used before the consolidation; that is, there was no attempt made to standardize and compare the stope costs of all mines. The general cost sheets for all mines, however, were standardized, and cumulative labor cost sheets were compiled in the general superintendent's office. At most of the mines, a daily record or distribution sheet for each working place was kept, showing the number of men, hours of drilling, hours of timbering, hours of tramming, cars of ore, cars of waste, sticks of powder and feet of fuse. This information was kept by each shift boss and entered on the distribution sheet by him or, at some mines, by a tram boss. The superintendent solved his own problems under the direction of the general superintendent, but without coming in touch with other superintendents, either through records or general conferences. Probably 95 per cent. of the stopes were square-set worked by day's pay; there were some back-filling and shrinkage stopes. Many of the development places, such as shaft sinking, station cutting, drifting and raises had always been run by contract. These contracts were given, for no definite period, at so much per linear foot and were measured monthly, or when completed, the men being paid monthly. In some cases, fairness to the employee was not maintained. On the whole, there was no standardization. There were no stope contracts, because of the objections of the Western Federation of Miners to general contracting in the mines. Changes in Stoping Methods Early in 1916, W. B. Daly, then general superintendent, and the author, then assistant general superintendent, visited the Southwest mining districts with the object of finding some improved mining

Jan 1, 1923

By Carlos A. Ferreira, Betina Hansen, Marco A. S. Rodrigues, Marcela P. Proença

"Nowadays, the concern with the reduction of industrial pollution has motivated researchers to found out new technologies for treatment of industrial waste. The clean technologies, as electrodialysis, are capable of treating these residues, minimizing the impacts when they are discarded directly on the environment. Membranes of SPS/HIPS, PAniCSA/SPS/HIPS, SPAN/SPS/HIPS were developed using chemical mixture method. Membranes were characterized by Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Dynamic Mechanical Analysis (DMA) and Scanning Electronic Microscopy (SEM). Membranes were submitted to electrical polarization and to electrodialysis at NaCl and KCl solutions, in order to determine ionic transport through the membranes. Results were compared with commercial membranes. The average percent extraction for Na+ ions obtained by membrane was beyond 20%.IntroductionThe high environmental impact caused by the galvanoplastic industries represents today a world concern(1). In the galvanoplasty, thin metallic layers are deposited on metallic surfaces(2) through chemical methods or electrochemical process. This industrial process presents some disadvantages that limit its utilization, as the generation of toxic effluents containing concentrations of heavy metals usually above the limits allowed for his release in receiving bodies(1), the production of galvanic sludge which is considered hazardous waste and that is very difficult to treat, beyond the high consumption of water (3).Stimulated by the development of new ion-exchanged membranes with high selectivity, lower electrical resistance, and improved thermal, chemical and mechanical properties, the use of electrodialysis in the wastewater treatment has recently gained a broader interest(5). The electrodialysis (ED) is a mass separation process in which electrically charged membranes and an electrical potential difference are used to separate ionic species from an aqueous solution(5). The technique permits the recovery and the reutilization of the waste products from the industrial process, avoiding the discharge of them on the environmental (acting as clean technology)."

Jan 1, 2008

By L. D. Stamp

In view of the comprehensive accounts which have appeared in recent years of the oil fields of Burma, Assam and the Punjab,' this brief account will be restricted to an outline recapitulation of the position of the fields and a note on progress and developments in the last two or three years. It is actually peculiarly difficult to give an account of recent developrnents in the oil fields of the Indian Empire. The companies naturally are compelled to make a return to the Government of India of oil produced. These figures are published annually (about 10 months later) for each administrative district (which may include more than one field) where oil is produced, in the Annual Review of the Mineral Production of India (Records of the Geological Survey of India). Some details of recent developments may be given in the Annual Report of the Geological Survey of India (also published in the Records), but otherwise the companies tend to preserve a policy of extreme secrecy. Some of the smaller companies usually publish wellhead production month by month in order to encourage their shareholders when such figures are encouraging, but the larger companies do not necessarily even give figures of production in their annual reports to shareholders. Occasionally details of new tests, new machinery, and so on, leak out through the daily or weekly press in India, but, except for generalized official statements, no details :ire available as to the number of new wells, depths, wells abandoned, or other figures which are common property in other parts of the world. In the country itself the geologists preserve the utmost secrecy, and at times quite a serious system of espionage is developed. Of recent years there has been a slight tendency towards the pooling of experience, but actually the Indian Empire, particularly of course Burma, where there is a

Jan 1, 1933

By A. E. Nash

This title is somewhat of a misnomer, because it does not accurately describe the phase of heat generation and application coming within the scope of this discussion. This paper is concerned primarily with that particular phase of radiant-heat transfer sometimes erroneously referred to as "shielded" radiant heat, to differentiate it from the open radiant heat of either flame or settings, in which the actual source of the radiant heat is a small incandescent furnace composed of a highly conductive superrefractory, within whose walls the combustion of the fuel is completed. This small furnace is usually located directly in the furnace proper, and although its refractory walls do shield the heat-absorbing surfaces from contact with the gases of combustion, there is no interference with the radiant heat given off by the furnace itself. We do not believe it either necessary or advisable to shield or screen radiant heat when properly controlled and applied. We do believe it essential to prevent the excessively hot gases of combustion from coming in contact with those parts of the heat-absorbing structure that are already receiving heat at high rates by radiation. In connection with any process for the refining of oil with which we are familiar, we are convinced that it is most advantageous to transfer the maximum of the heat generated in the form of radiant heat, applied directly to the heat-absorbing surfaces without the interposition of any form of shield or screen to prevent or reduce the radiant-heat transfer. While the term radiant heat is broadly used to cover all heat energy transferred from one body to another by radiation, in contradistinction to heat given up by gases in direct contact with the heat-absorbing structure (convection) or transmitted simply by conduction, in furnace work it is perhaps more often limited to the heat rays given off either by

Jan 1, 1928

By Theodore Holt

Outline of the Process THE Mines Operating Co.'s plant at Park City, Utah, was designed to treat the low-grade fillings in the old stopes of the Ontario mine. These fillings carry 6 to 14 oz. of silver, 1 to 2 lb. copper, 0.01 to 0.015 oz. of gold, and a small percentage of lead and zinc. The treatment consists in mixing the crushed ore with coal dust and salt and then roasting in a new type of furnace y combustion of the contained fuel. The roasted ore is leached with an acid salt solution to dissolve the silver, gold, copper, and lead. At present these metals are precipitated together on scrap iron and the product sold to a refinery. The only new feature of importance in this scheme of treatment is the roasting process, which makes possible the chloridizing of ores without any loss of the valuable metals, and at a very low cost. History of the Development of the Process The roasting process had its beginning in connection with research work at the Utah State School of Mines. N. C. Christensen, Jr., who held one of the School of Mines' fellowships, was engaged in some experimental work on blast roasting. At the same time I was doing some work on the insoluble gold in Mercur base ores. Mr. Christensen roasted some of this base gold ore in his pot furnace, and found that when he mixed a sufficiently low percentage of fuel with the ore, it did not sinter but roasted to a leachable product. We considered this a new application of blast roasting, and proceeded to test out a large number of ores in several different types of small roasters which we constructed. This experimental work continued well into the summer of 1911.

Jan 7, 1914

By John B. Hastings

CHIEF among the varied problems facing the mine-manager is that of vein-structure and origin, which is highly important as a guide to successful discovery and development. If metalliferous deposits can be traced to the intrusion of waters along definite lines, then is there something tangible for him to study. But when he is told by a geologist that metalliferous deposits are due to some other cause, like magmatic differentiation, while not perhaps discouraged, he is impressed with a vague sense of new worlds to be conquered. In 1897, while manager of the War Eagle mine at Rossland, B. C., where, previously, the ore-bodies had not been supposed to occur as veins, I suggested to visiting members of the Canadian Geological Survey that, perhaps, the structure of the pyrrhotite-bodies of that mine, which had been proved to occur along well-defined fractures, might throw some light on the similar deposits of Sudbury, then held to be basic aggregations from the original magma. Later investigation has at least provoked discussion of this last deduction, questioning its correctness and suggesting that, perhaps, the deposits are actual veins. The following extract from a paper by J. E. Spurr 1 is quoted, because it sets forth Mr. Spurr's theory of the quartz-occurrences of the Silver Peak mines, which will be discussed in this article. It also graphically describes the attendant geological features. '' The Drinkwater group of mines, which is the most important part of the Blair gold properties, and which has produced practically all of the million dollars' worth of ore, as above stated, may be taken as typical of the gold-veins which, though widespread and numerous, show a wonderful similarity of character. On the surface two adjacent veins outcrop, the Crowning Glory and the Drink-

Jan 1, 1913

By Piotr D. Moncarz

As major urban areas begin to run out of "good-terrain" for their expansion, they begin to claim high water-table areas within or adjacent to water fronts or swamps. Similarly, major infrastructure projects encroach on or cross high organic content areas. The associated major structures often require deep foundations located in soils investigated through core samples removed at a discrete number of locations. The investigation is nearly always preoccupied with soil mechanical properties, sometimes with soil non-organic chemistry for concrete and metal corrosion, seldom, if ever, for organic-chemistry and bio-conditions as related to concrete longevity. Not surprisingly so, bio-corrosion of concrete is one of the least understood phenomena by practicing civil engineers. This paper shows how low-iron, organic-rich sediments may trigger sulfate degradation of concrete, even when standard pre-construction chemical analyses indicate only a moderate sulfate level. The discussion is illustrated with a case of a pile foundation in the United States driven into marine channel sediments and sediment-derived fill material. The concrete piles lost their structural integrity due to secondary ettringite formation and depletion of iron in the cement paste. Disintegration of concrete occurred only where it contacted superficial marine sediments and sediment-derived fill material. Concrete in direct contact with seawater or native sand and silt materials appeared to be sound. Sediments in contact with the degraded concrete were highly anoxic and had a history of sewage contamination, contained low concentrations of total iron (<2%), Fe(III) (<0.3%) and moderate levels of sulfate (1500ppm), and exhibited high bacterial activity. This environment resulted in the microbial dissolution of Fe(lll)-rich ferrite in hardened cement paste. Iron depletion in the cement paste had made the concrete vulnerable to degradation by sulfate, even at moderate levels of sulfate concentrations in the sediments.

Jan 1, 2002

By J. F. Barkley

"In trying various coals at one of the Government power plants, comparison was made of the ash softening temperature of each coal, with the clinkering tendencies of the coal when burned in the furnace. The proximate analyses, ash softening temperature and plant reports as to clinkering were tabulated. It was desired to bring out any correlation that might appear between the ash softening temperature found in the laboratory, and the clinkering of the ash as found in the boiler furnace.Each coal used was sampled and analyzed, and the standard ash fusion test made. The clinkerring of the coal in the furnace was observed by the furnace operator. The furnace equipment consisted of the ""V"" or Murphy type of stoker with the ordinary fire-brick arch roof. With such arrangement very high furnace temperatures are apt to be produced at the ratings carried at this plant.The softening temperature of ash is defined as the temperature at which small cone of the ash, as tested in the laboratory furnace, has fused down to a spherical lump, The softening interval is the difference between the softening temperature and the temperature at which the first rounding, or bending, of the apex of the cone takes piece. The flowing interval is the difference between the softening temperature and the temperature at which the ash has reached a fluid condition as shown by spreading out over the base in a flat layer.While the analyses of the different samples of the some coal did not vary appreciably, the ash softening temperatures were not always so consistent. It will be noted from the following examples that the ash softening temperatures of different samples of the same coal differ as much as 290° F, Hence, in order to judge this property of a coal, many samples ore desirable, taken from many different shipment."

Aug 1, 1924

By T. F. Witherbee

IN a paper read at the Lake Superior meeting, August, 1880, an account was given of the successful use of Rendrock and Monaky powder upon a scaffoldn and salamander in the furnace. On April 5th, 1881, the same trouble called for like treatment, which, though not so immediately. successful, was on the whole more instructive than the first trial, and points, I trust, to a reasonably sure remedy for all such difficulties. Up to December 4th, 1880, foundry and mill iron were made from Old Bed and New Bed magnetite, and Kearneyy red hematite, when a return was made to Bessemer iron, from an inferior quality of New Bed ore as compared with that used during first blast. January 18th, 1881, New Bed, Chateangay, and East-shaft, a newly-opened Bessemer deposit of Messrs. Witherbee, Sherman & Co., were first used, and continued up to February 13th, on a fuel charge of 80 per cent. anthracite and 20 per cent. coke, the product on the three ores being about 10 tons more per day than on New Bed alone. From this time until March 11th all coal was used, and New Bed, Chateangay, and East-shaft ores, up to February 22d, and from that date Chateangay and New Bed, the product falling off 9 6/10 tons per day as a result of not using coke. It is fair, however, to state that the furnace was not in good condition during&apos; this period, being over-burdened, and the New Bed ore was, temporarily, uncommonly poor, for reasons of no particular interest here.. It required to properly flux it at least 140 per cent. of limestone; and 101 per cent was actually used. March 11th, all Chateangay ore and 80

Jan 1, 1882

By A. C. Lyons, A. J. Reed

INTRODUCTION A trend which is obvious in the United Kingdom and is thought to be evident in other parts of the Western world is the disproportionate rise in the cost of tunnel mining labour compared with other tunnel cost increases. This disproportionate increase in labour costs has been accompanied by, and may be the result of, a shortage of skilled working labour. To combat this problem there has been a steady increase in the use of machines for excavation and for the erection of tunnel linings to keep the amount of skilled labour working below ground to a minimum. The typical tunnelling cycle, where the ground needs continuous support can be excavation, temporary support, temporary lining, grouting and permanent lining. It is obviously an advantage to combine as many of these operations as possible and carry out as much as possible by machine. Machines have been developed which will, either alone or used in combination with a shield, excavate and, when necessary, temporarily support the excavation. If a segmental lining is used, it can be so designed that it will form the permanent lining and reduce the cycle time and skilled labour requirement to a minimum. In cases in which the ground can be cut accurately to a smooth profile and will stand without support for a sufficient time, the lining can be expanded against the ground and the necessity of grouting eliminated. In cases in which ground will not stand without support, the usual method is to use a bolted lining and to grout behind it preferably as the shield is shoved forward. Whichever technique is used (this is largely determined by the ground) it is an advantage to make the segments as large

Jan 1, 1974

By Tracy T. Morris, Luis G. Navaro

"Anodic copper slimes produced during the electrolytic refining of copper are routinely batch leached to remove copper. At the Amarillo Copper Refinery, an atmospheric leaching process was converted to an autoclave pressure leaching system to improve the removal of copper, reduce the consumption of oxygen, improve leaching times and enhance tellurium recovery. The benefits of pressurized versus atmospheric leaching of slimes were soon realized by obtaining the desired level of decopperization in a shorter time and with lesser quantities of reagents. The autoclave was designed and constructed with a unique oxygen injection system that enables good control of the leaching process and with no plug-ups. Other features include a mass measuring system that balances the quantity of slimes to be leached to the desired final solution concentration based on initial feed concentrations. The end result was a more efficient and controllable leaching process for removing copper from anode slimes.IntroductionThe electrolytic refining of copper consists of an electrolytic cell filled with a sulfiiric acid based electrolyte and pairs of copper anodes and cathodes. When a current is applied, copper in the anode dissolves and is plated onto the cathode. Impurities within the anode that are more noble than copper do not dissolve and end up at the bottom of the cell and are referred to as slimes. Gold and silver are the main slimes constituents of interest because of their monetary value, but there typically are significant quantities of selenium, tellurium, lead, antimony, arsenic, bismuth, nickel, silica and tin. Copper is also present, usually as a metallic or as a reactant with tellurium, selenium, oxygen or sulfur and can range from 10 to 30% of the slimes fall."

Jan 1, 2012