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By T. M. Chance

The first bituminous coal cleaning-plant to use the sand-flotation process1 was placed in operation on Oct. 1, 1925, at the tipple of the East Broad Top Railroad & Coal Co., at Mt. Union, Pa. The general principles governing the design of plants of this type and typical operating results of anthracite sand-flotation units have been previously outlined.2 I will, therefore, confine myself to a description of this particular plant and to some of the elements of design it incorporates. The Original Mt. Union Tipple The plant was installed to transfer coal.from steel narrow-gage cars of 60,000 and 70,000 lb. capacity to standard-gage equipment. The coal was hauled about 30 miles from the East Broad Top field. This coa1, mined by the Rockhill Coal & Iron Co. and other operators, is a low-volatile slow-coking coal with ash of high-fusion point. It is normally a high-grade coal that does not contain an excessive amount of free impurities, but it requires careful handling to secure a fair domestic yield, and, naturally, the need for narrow-gage transshipment increases the difficulty of the problem. The narrow-gage cars were discharged into an 8-car track hopper equipped with two feeders passing the coal to two 42-in. apron intake conveyors. Twin units were installed throughout the original plant, two lump-and-egg shaking screens, two lump picking-tables, two egg picking-tables and two stoker conveyors. The stoker coal was loaded without cleaning. The loading tracks and booms were in duplicate and, with the layout as originally installed, either unit could be run independently, each unit shipping a different class of coal or both units making the same product.

Jan 1, 1927

By Edmund Newton

The steel industry of the United States has depended in the past almost wholly upon imports for its supplies of manganese. Many of the important domestic sources yield ores leaner in their natural condition than the foreign ores the steel industry. has been accustomed to use. To make them available, therefore, either the ores must be concentrated or the practice of the steel industry modified. Roughly 25,000 T. annually of high-grade manganese ores are used for dry batteries for chemical purpose, and in other ways; while approximately 750,000 T. are required for making steel. , By present practice, every ton of steel takes an average of about 14 lb. (1.8 kg.) of metallic manganese. This is generally added to the steel in the form of an alloy, the standard alloys being the 80-per cent. ferro-manganese and the 20-per cent. spiegeleisen, During the year 1917, 286,000 T. of ferromanganese and 193,291 T. of spiegeleisen were made in this country, the former largely from imported ores; and 45,381 T. of ferromanganese. was imported. The metallic manganese represented by these alloys was 304,000 T., the product of roughly 800,000 T. of high-grade ore and 345,000 T. of low-grade ore. Manganese Deposits in the United States Before the war manganese ore was mined in relatively small quantities in the Appalachian region, including Virginia, Tennessee and Georgia, and in Arkansas, but owing to the increase in prices during the past three years manganese mining has been undertaken also in Montana, California, Arizona, New Mexico, Nevada, Utah, and Minnesota. From data now available it appears that in this country deposits of high-grade manganese ores are usually small, while materials lower in manganese and higher in iron occur in appreciable quantities. Our total quantity of manganese-bearing material is relatively large, but on

Jan 1, 1920

By J. A. Church

I. Early Furnaces,......423 11. Experiments with the HIgh-Shaft FURnace,..... 426 III. ExperMents wIth the Wide FURnace,..429 IV. ExperEentS with Extreme BOSH,... 43.2 V. Survival of the 56 by 180 IN. Furnace,.434 VI. Recent ExpeEiments,.....436 VII. SUMMary,........438 I. Early Furnaces. Copper blast-furnace construction in America has long recognized a general standard in the rectangular water-jacketed shaft with separate forehearth. The details, however, and especially those relating to shaft dimensions, have had to meet a great variety of conditions, and show no uniformity whatever. Selecting a few of the present day Western plants, we find furnace lengths varying from 12.5 to 87 ft., widths at tuyere level from 42 to 84 in., and heights above tuyeres from 5 ft. 4 in. to 22 ft. 4 in.; and comparing present designs with those of the past, we meet contrasts no less striking. Unlike its transverse section, the length of a furnace has come to depend rather on the size of unit desired than on the requirements of smelting; and if the question of length be ignored, several of the various existing designs can be grouped together on the basis of a common transverse section. This section, having a width at tuyere level of 56 in. and a height above tuyeres of 18 ft., was developed at Great Falls, and the story of its development contains some interesting features. Ground was broken for the Great Falls works in the spring of 1891. About a year later, the concentrator was able to begin operation, followed within the next few months by the Brueckner, reverberatory, and converter departments, and in April, 1893, by the first blast fur-

Jan 1, 1914

By Marshall K. I

THE problem of satisfactorily eliminating the fumes and dust which are unavoidably produced in various metallurgical and manufacturing industries is one which has received considerable attention in the past, and has been the subject of much investigation and research. The solution of this problem was urgently desired for two reasons, the principal one being the fact that a considerable percentage of the total process losses in many industries was represented by the commercial values of the fumes and dust that escaped from the stack.The other reason is that, in some instances, the emission of the matter is regarded as objectionable. Various methods have been designed with a view to solving the problem thus presented, and the latest development that has beendesigned is the process of electrostatic precipitation. Continued investigational and developmental work with this process has already demonstrated its applicability to many industries, and new uses to which the process can be put are being opened up. Its use is already widespread, and the economic success that has attended its application in most instances would indicate that its use will become more general in the future.It has proved its ability to treat gases over wide ranges of temperature, and has successfully handled various types of fumes whose chemical characteristics differ very considerably. In many processes it has now come to be regarded as standard equipment.HISTORY OF ELECTRICAL PRECIPITATIONThe first recorded observations on the influence of an electrified insulated wire on gases containing solid particles in suspension was made as early as 1824 by Hohlfeld, in Leipzig. He found that, if he electrified a wire hung in a bottle filled with smoke, the smoke cleared rapidly, and a deposit formed on the sides and bottom of the bottle.

Jan 1, 1923

By G. R. Mansfield

THE third year of Government exploration f or potash by the U. S. Geological Survey and-the U. S. Bureau of Mines under the authorization of the act approved June 25, 1926 (Public 424-69th Cong.) is drawing to a close. The results thus far obtained are thought to be sufficiently interesting and satisfactory to justify the presentation of a brief preliminary account of the work. REVIEW OF EARLIER EXPLORATION The general geologic similarity of the Permian basin of Texas and New Mexico to the potash field of Germany had long ago suggested the possibility of the presence of potash salts somewhere in that basin, but petroleum exploration was then making little headway there and the necessary data could not be obtained. The discovery by Udden in 1912 of potash in brine from the Spur well in Dickens County, Texas, was the first direct evidence of its presence. In 1915-17 the U. S. Geological Survey drilled a test well with standard tools at Cliff side near Amarillo, but failed to find potash. Nevertheless, an observer has been kept in the field, at first in cooperation with the Texas Bureau of Economic Geology but since 1922 by the Survey alone, to `secure data and samples from oil and gas tests. Since the discovery of oil in Reagan County in 1923 exploration by drilling has been rapidly extended to many parts of western Texas and southeastern New Mexico. The identification of the potash-bearing mineral polyhalite was first announced by the Geological Survey in June, 1921, the material having come from cuttings from the Bryant well in Midland County and the Burns well in Dawson County, Texas. Successive discoveries and announcements of similar purport aroused widespread interest in potash exploration, which culminated in the action by Congress already noted.

Jan 1, 1929

By V. H. Wilhelm

The year 1936 was a prosperous one for the oil industry in California. Increases in crude prices were posted in February and March. Re-establishment of voluntary curtailment in February was a factor in holding production at an efficient level throughout the year. Reduction of storage was effected through adherence to curtailment measures, aided by greater demand and smaller average well completions. During the first six years of voluntary curtailment, allotments were increased during the summer season and reduced during the winter season. This year, good results were obtained through a revised system of allocation, by which the California monthly quota was held constant at approximately 540,000 bbl. per day. After a 7-month period of practically unrestricted production (ending in January 1936), numerous operators found that curtailment was still necessary, as California and export market,s were not yet capable of absorbing the state's potential production, which was estimated to be in the neighborhood of 850,000 bbl. per day. Therefore, in February California operators again placed themselves under voluntary curtailment; with the result that state production dropped from around 700,000 bbl. per day in January to a low of 565,000 bbl. per day in April, and increased gradually to around 585,000 bbl. per day for December. Drilling activity during the year increased about 10 per cent over that of the preceding year, although the resultant production per well decreased. Field Discoveries As a result of a very active wildcatting campaign in California, aided by better interpretation of geophysical data, five new oil fields and two new gas fields were discovered. Oil Fields Greeley Field, Kern County.—The Standard Oil Co. added to its list of djscoveries by drilling and completing its K.C.L. No. 11-1 well at a

Jan 1, 1937

ONE of the problems that confronts the chronicler of the Porphyry story is to determine the date from which Morenci should be regarded as one of the group. The mines have the distinction of being the first operated in Arizona for copper. A small smelter was in operation as early as 1873 and in the eighties two smelters accounted for a substantial production ranging from 3,000,000 to 6,000,000 lb. per year. The first concentrator was built in 1886, but the ores were principally oxidized, and direct smelting ore still supplied most of the production. As early as 1893, the mining of somewhat leaner porphyry ores, containing copper in the form of the sulphide mineral, chalcocite, was commenced; but these still were of comparatively high grade and the concentrators were plants of 100 to 400 tons daily capacity. Moreover, the backbone of operations was still the production of rich oxidized ores for direct smelting. They assayed 10 to 15 per cent copper and the sulphide milling ores assayed 3 to 4 per cent. A significant comment appears in the Copper Handbook for 1908. Speaking of the Arizona Copper Co., Ltd., which was to become the most important component of the present Morenci enterprise, the editor, Horace Stevens, says: "A tremendous amount of ore is in sight, ore reserves . . . being estimated at 10,370,600 tons . . . " It seems fair to infer from this that the property was not yet regarded as an immense low-grade mine, but that the copper content of perhaps 70 lb, to the ton made an ore of "medium " grade even according to the standards of the time. Although the concentrating ore was typical of that in the porphyry group of mines (except for its greater richness), no one seems to have the least inclination to take from Utah the

Jan 1, 1933

It is almost eight years to the day when we launched the original SAMREC Code in March 2000. Since that date I think the SA minerals industry has matured beyond recognition in its approach to reserve and resource reporting, and I believe we can be justifiably proud of that progress. Many of those companies that have led the way in reporting standards are listed on our sponsors list. We thank them for their sponsorship but even more for their considerable support in all aspects of the SAMCODE organization. Matt Mullins, my co-speaker here today, has been instrumental in the revision of the SAMREC Code over a long period of time and also took up the reigns with the SAMVAL Code after the retirement of Rob Croll. I would like to formally thank Matt for his immense contribution in producing the two Codes; he can take great pride in the final product and fully deserves the many accolades that we have already received from our international counterparts. He has done all this whilst still maintaining a very demanding day job at BHPBilliton. Matt will be the first to admit that he has received tremendous support from more than 100 people who participated in the various working groups, many of whom are employed by our sponsors. There are obviously too many to mention by name but they deserve a big vote of thanks for their personal contributions. In addition to launching the two Codes we are also launching our ?branding? initiative with our own SAMCODE logo and the SAMCODE website: www.samcode.co.za. All the slides used in the presentation today will be on the website later today as will a newsletter which will serve as a media release.

Jan 1, 2008

By C. H. Herty

The results of a study of the open-hearth process from the physicochemical viewpoint are given. This study includes experimentation in small laboratory furnaces and in standard 100-ton furnaces. The behavior of manganese, carbon and phosphorus are quantitatively explained. The action of "residual" manganese is discussed with reference to its relation to iron oxide dissolved in the metal. The solubility of CO in steel and its relation to dissolved FeO and carbon is given. The equation for phosphorus elimination has been tested out on a 200-ton furnace and the results are given in the text. The effect of temperature and slag composition on the elimination of metalloids in the basic open-hearth process has been qualitatively understood since the early days of steel making. The quantitative effect has, however, only recently been brought to attention. The effect of slag composition has received more attention than that of temperature, primarily because the range of finishing temperatures in the basic open-hearth process is small compared to the large variations found in the composition of the slag at different periods during the process, and to the variations occurring with the use of raw materials of different degrees of impurity. The effect of slag composition on the elimination of metalloids has been studied by Styril from the thermochemical standpoint. This method is open to serious errors, in that thermochemical data at 2900' F. are very inaccurate and in many cases completely lacking. Feild2 has calculated equilibrium constants from the rate at which the metalloids are eliminated. The effect of slag viscosity on rate of elimination will affect the constants calculated by this method. Whitely,a Colcough4 and others have used slag compositions as the basis for calculation of constants by which the extent of elimination may be calculated.

Jan 1, 1926

By Coulter L. J

THE method of stope surveying as practised at the Mount Lyell Company's mines has been evolved out of the exigencies created by special conditions. It presents some novel features, and has proved effective for all requirements. All stope measurement work is brought under one complete system, to which office methods are standardized. Before proceeding to deal with the subject a brief description of the physical characteristics of the ore-bodies of each mine and the method of stoping will serve to show, cause ,for departure from ordinary survey practice.NORTH LYELL MINEThe ore-bodies of this mine occur on or near the conglomerate schist contact, and, being probably the result of replacements of both rocks, they rarely present any definite walls. It is usual for the payable material to merge into the respective countryrocks, and the limit of the occurrence is defined rather by assay value than by any distinct natural boundaries. The general configuration of these ore-bodies, therefore, is highly erratic both in horizontal and vertical section, so that, in order to obtain an accurate record of any occurrence, the measurement of the actual contour at short vertical intervals is essential.Stoping is carried out on a modification of the "rill." system, perhaps more properly described as "arched back" or "dome" stoping. Mullock rises are placed in as convenient positions as the erratic configuration of each ore-body will allow, and aroundthese rises the back is kept well arched, both longitudinally and transversely. The larger stopes are divided into arbitrary sections in which ore-breaking and mullocking are carried out in rotation, so that the whole of the excavation is seldom open for measuring at anyone particular time. Stacking or square-setting on the...

Jan 1, 1915

By Samuel Shallcross

THE principal function of the Bell limestone mine, of the American Lime & Stone Co., at Bellefonte, Pa., is to supply raw material to the company's modern rotary kiln plant at Bellefonte. Because mining costs are naturally higher than many open quarries with more favorably lying strata, it cannot compete, except to a limited extent, in the markets for road material and fluxing stone. In the broad sense, mining does have an advantage over the average open quarry when the end products are designed for and controlled by process and final inspection for the exacting demands of the industrial and chemical markets. Approximately 80 per cent of the output of the Bell mine is sold in the industrial and chemical markets. And as higher standards are set each year for construction and agricultural work, the remainder of the mine output goes to these two classes. Mining produces more fines than open quarries, and these fines are difficult to market; on the other hand, owing to absence of contaminating clay and impure rock, a greater percentage of the output of a mine is marketable. Because of the great production of fines, rotary kilns for lime burning are necessary when the stone must be mined. In 1921 the American Lime & Stone Co. operated 19 quarries and 72 lime shaft kilns spread over an area of 40 miles between Bellefonte and Altoona, Pa. At that time the line-production capacity of the 72 kilns amounted to approximately 700 tons per day. After 15 years the company operates three rotary kilns and six shaft kilns, with a combined output of approximately 500 tons of lime per day, concentrated in its single Bellefonte plant (Fig. 1). Its only stone-producing plants are now the limestone mine at Bellefonte and a construction-stone open quarry at Union Furnace, near Tyrone, Pennsylvania.

Jan 1, 1936

By Keith G. Kirk, Lawrence E. Welborn, Patrick A. Ley

Over the past two years the Office of Surface Mining in conjunction with Energy & Minerals Technology Assessment, ENCORE Systems Inc., and Boeing Computer Services has developed the Economic Coal and Ore Reserve Estimation (ENCORE) Coal Seam Modeling System. This system is being used by OSM, certain states, and industry for mine planning and mine plan permit review. The ENCORE system enables the mining engineer to start at the reserve estimation stage of surface mine planning and continue through the entire mine planning process and into the permit preparation process. The ENCORE system enables the state and federal regulatory authorities to assess a given mining and reclamation plan permit application in a rapid and efficient manner and greatly speeds up the mine plan review and permitting process. The ENCORE system is user friendly and menu driven thereby permitting the engineer with minimal computer training to rapidly learn and utilize the system. Data are input both through digitized map files and bore hole information files and stored in a data base that is an integral part of the ENCORE system. The system performs reserve estimation through standard polygon methods, least square methods, and geostatistical (kriging) techniques. Geostatistical routines permit rapid evaluation of coal and overburden quality and quantity. System outputs include drill hole sumnary and resource summary reports, cross sections, isopach maps, structure contour maps, premining topography maps, postmining topography maps, and three-dimensional perspective views. The maps can be displayed on a high-resolution, color graphics terminal or generated by a high quality plotter and are suitable for direct inclusion in the mining and reclamation pl an permit application. This paper gives detailed examples of ENCORE'S use together with example outputs.

Jan 1, 1983

On August 22, 1966, just 20 months after writing sales agreements with Japanese steel mills, Hamersley Iron Pty Ltd made its first contractual shipment of 52,000 tons to Yawata Iron and Steel Co Ltd. As world news, the event was not spectacular. But to mining men it represented an astonishing achievement. Twenty months of feverish effort and the expenditure of more than $100 million had created a large open-pit iron ore mine, a crushing plant, storage and load-out facilities for sized ore, and a supporting township at Mt Tom Price; a 182-mile standard gauge railway; and port and loading facilities for a nominal loading capacity of 6000 tph as well as a port town, Dampier, on King Bay. The project was executed in the sparsely inhabited, arid, dissected-plateau country of the Hamersley Range in the northwest sector of Western Australia. Hamersley, 60% owned by Conzinc RioTinto of Australia Pty Ltd and 40% by Kaiser Steel Corp, holds sale contracts for ore and pellets valued at $770 million. The main contracts are with the Japanese, who are to be supplied with 65.5 million tons of ore during the 16 years from August 1966 to August 1982 and 18 million tons of pellets over a 10-yr period beginning in early 1968. Of lesser importance at this time, but presaging trends, are contracts for a total of nearly 1.5 million tons to be shipped to England and Western Europe during the years 1966-68. A pellet plant with a capacity of 2 million tpy is now under construction at Dampier and is to be on stream early next year. Another interesting project for which the plans are set, is a desalination plant for sea water to supply industrial requirements and potable water for the town of Dampier.

Jan 5, 1967

By G. Landry

"IntroductionThe Cape Breton Development Corporation (CBDC) is constantly searching for new technologies that will enhance the marketability of its coal. One technology which shows promise in utilizing Cape Breton coal while at the same time addressing the traditional problem of high sulphur inherent in the Sydney coalfield, is coal-water fuel (CWF).The CWF process incorporates a physical change of coal by grinding it to a flour-like consistency and then mixing additives with it to make a fine coal slurry. The result is a liquid dispersion of fine coal particles that looks like oil, stores and flows like oil but burns like coal. The equipment used in the CWF process is standard mineral processing equipment but application of the equipment to manufacture a specific coal particle size and the specified additives used in the mixing make it a unique technology.The product, which CBDC calls Carbofuel, consists of 70% coal, 29.5% water and 0.5% chemical additives. The key properties of the product are: (I) high solids loading, (2) medium viscosity levels, (3) stability against sedimentation, and (4) good atomization behaviour. Carbofuel specifications are presented in Table I. Carbofuel ProductionThe production of Carbofuel is based on the controlled processing of coal. This involves wet grinding of the coal to a specified fine size (-250 um), cleaning this fine product to remove mineral impurities and formulating (with chemical additives) a finalproduct from the cleaned coal. The flow diagram in Figure 1 indicates the processing circuit for Carbofuel production.CBDC operates a 7-tonne-per-hour continuous production plant complete with state-of-the-art control, full laboratory services, product storage and loadout facilities. The plant has operated since 1983 and has produced over 12000 tonnes for several major demonstrations. The plant is shown in Figure 2."

Jan 1, 1987

By D. L. Kowal, P. J. Whittaker, M. A. Tuzun, N. O. Lotter

The area of flotation testing of drill-core is important in the business plan of most mining companies. Metallurgical information derived from this practice can be used to advantage in strategic decision-making. Sampling, flotation testing and subsequent Qem SCAN analysis of a mineral resource is one example of this approach. Anew resource, located in Sudbury, Ontario, is being assessed for the Sudbury Operations of Falconbridge Limited, which includes the Strathcona Mill. In this case, it was possible to improve the value of information from sampling and flotation testwork by using an improved, statistically-based test design, by sampling the resource by generic end-member ore type, and by integrating the Mineral Processing and Mineral Science disciplines into a Process Mineralogy team. In addition to producing standard metal grade and recovery information, this new approach provides more reproducible information from representative samples and flotation testing in a replicate format. Qem SCAN technology is used to produce a size by size mineral balance, including both modal percentages and liberation, from which flotation models for each ore type can be developed. As a result, a key understanding of the potential behaviour of a given ore type, if mined and then processed at the current mill operation, is gained at the 95%confidence level. The three ore types of this mineral resource were shown to have different flotation characteristics. Quantifying the mineralogy and liberation in each of the three ore types, has shown that this difference is due to changes in modal percentages of ferro-magnesium and magnesium silicate minerals such as pyroxene, talc and serpentine. Liberation across the three ore types is very similar and is therefore not responsible for variation in flotation performance.

Jan 1, 2003

By H. P. Greenwald

Those interested in the early developments and experiments, both in the United States and abroad, that led to modern rock dusting, will find an excellent summary in a paper by George S. Rice,13 published in 1914. The period from 1914 to 1924 was one of intensive experiment on coal-dust explosions in the United States; abroad, war activities and rehabilitation stopped this work over a large part of that decade. American findings were published by the Bureau of Mines, particularly in Bulletins 167 and 268. It is convenient to consider that in the United States rock dusting to prevent coal-dust explosions in mines was initiated in 1924 with the publication of tentative specifications.17 This was followed in 1925 by an investigation of methods and costs12 and approval by the American Engineering Standards Committee of a Recommended American Prac-tice.18 Approximately 13 years have elapsed since this approval, and inasmuch as changes in rock-dusting practice in the United States have been evolutionary, it is necessary to consider this entire period as "recent" in some phases of the work. There have been no official changes in the Recommended American Practice since its approval. This paper reviews as briefly as possible knowledge acquired since the issue of the earlier papers mentioned, through experience in mines and experiments conducted by different organizations engaged in the promotion of mine safety. Size of Rock Dust The Recommended American Practice states that the dust shall be 100 per cent minus 20-mesh and 50 or more per cent minus 200-mesh. Results of large-scale tests on the relative effectiveness of rock dust of different sizes were published by the Bureau of Mines15 in 1933 and are reproduced here as Fig. 1. The limiting curve of this figure shows that

Jan 1, 1940

Prospecting methods used in Tennessee have gradually improved with the years, as required by depletion of the easily accessible and shallow deposits and the universal trend toward mechanization, and as necessitated by exploring deeper beds, often occurring under limestone and flinty overburden. In the early days it was a very simple matter to dig pits by hand, using a plentiful supply of local farm labor to expose relatively shallow deposits of "brown rock" under shallow clayey overburden that would stand up without timbering. Visual inspection of the exposed phosphate and expert judgment of the "grade" analysis, aided by a "biting" test to reveal presence of unwanted silica, furnished most of the information required. All this might be helped by a few samples sent to the local chemist† who supplemented his income by judicious trading or tanning a few bear skins. The extra curricula activities did not affect the accuracy of the analysis which hold up even under present day standards. Some shot and core drilling was done in Hickman County, mostly for the limestone-like blue Phosphate deposits. The next step was the use of a 4-in. posthole auger, hand operated as described by Guenther, followed by a completely mechanized rig, as described by Pickard. Both these methods are practically adapted to the prospecting of the relatively soft brown rock deposits at moderate depths of clay overburden. For prospecting in areas of deeper overburden, such as are often found in Hickman County, up to 150 or even 200-ft depths, a modified core-drilling method is described by Guenther. Johnston describes a special diamond-drilling technique, developed by TVA, to penetrate flint horizons, which was adopted by the International Minerals in chemical corporation to prospect in Hickman County where deposits had previously been prospected at considerable expense and with difficulty, by small, temporary, hand-dug shafts.

Jan 1, 1948

By R. L. Boyer, F. Morgan, M. Muskat

In the last several years a type of application of the fundamental permeability-saturation relationships has been developed which offers great promise in the interpretation of general reservoir performance.l-' In these developments no attempt is made to solve the detailed flow dynamics in actual oil and gas-producing systems. That problem still remains unsolved. But the permeability-saturation phenomena are incorporated in the analysis of oil-producing reservoirs in a manner such as to reflect the true role they play in controlling the gross reservoir behavior. In particular, they are introduced in such a manner as to determine the gas-oil ratio of the production at any stage of depletion, and, when combined explicitly with the so-called material-balance principles in differential form, one can obtain a differential equation describing completely the average pressure and gas-oil-ratio history of oil-producing reservoirs. While thus far they have been applied directly only to gas-drive reservoirs, they are susceptible of extension to partial water-drive systems, and qualitatively the same principles are of value in the study Of complete water-drive reservoirs. Moreover, in addition to giving a means for computing the variation of the reservoir pressure and gas-oil ratios vs. the cumulative production, they automatically lead to predictions of the gross ultimate recovery under natural depletion—and when properly extended they provide means for predicting the ultimate recovery under gas or water injection. The data required for such applications are the initial fluid distribution in the producing section, the pressure-volume-temperature data on the gas and liquid phases, and the permeability-saturation relationship for the oil-satuiated zone. The former can be obtained with reasonable accuracy by methods that are well established and available throughout the industry. The permeability-saturation data, however, involve techniques that are not at all standardized. In fact, only

Jan 1, 1947

By H. P. Greenwald

Those interested in the early developments and experiments, both in the United States and abroad, that led to modern rock dusting, will find an excellent summary in a paper by George S. Rice,13 published in 1914. The period from 1914 to 1924 was one of intensive experiment on coal-dust explosions in the United States; abroad, war activities and rehabilitation stopped this work over a large part of that decade. American findings were published by the Bureau of Mines, particularly in Bulletins 167 and 268. It is convenient to consider that in the United States rock dusting to prevent coal-dust explosions in mines was initiated in 1924 with the publication of tentative specifications.17 This was followed in 1925 by an investigation of methods and costs12 and approval by the American Engineering Standards Committee of a Recommended American Prac-tice.18 Approximately 13 years have elapsed since this approval, and inasmuch as changes in rock-dusting practice in the United States have been evolutionary, it is necessary to consider this entire period as "recent" in some phases of the work. There have been no official changes in the Recommended American Practice since its approval. This paper reviews as briefly as possible knowledge acquired since the issue of the earlier papers mentioned, through experience in mines and experiments conducted by different organizations engaged in the promotion of mine safety. Size of Rock Dust The Recommended American Practice states that the dust shall be 100 per cent minus 20-mesh and 50 or more per cent minus 200-mesh. Results of large-scale tests on the relative effectiveness of rock dust of different sizes were published by the Bureau of Mines15 in 1933 and are reproduced here as Fig. 1. The limiting curve of this figure shows that

Jan 1, 1940

With the advent of the First World Conference on Sampling and Blending (WCSB1) in Denmark in 2003 and the subsequent biannual meetings, together with other sampling conferences held on a regular basis, the central tenets of sound sampling practice and theory are spreading throughout the minerals industry. End-users and project houses, or groups who execute the projects, are all now better-informed about the principles of ?correct? sampling and preparation. To support this, many large mining companies now have their own in-house champion who will advise and ensure that the supply of sampling equipment is correct in terms of design and application, which further contributes to improved metallurgical accounting. The presence of a sampling champion also ensures that consistent and acceptable standards in regard to sampling practice are maintained throughout the group. This has, in turn, placed a greater degree of responsibility on the shoulders of sampling equipment suppliers, in terms of their equipment designs and product offerings, as well as applications knowledge for effective installation of equipment on client plants. This paper attempts to highlight the significant challenges that sampling equipment manufacturers often face with regard to complying with the newly understood requirements of best practice and sampling equipment design. Manufacturers invariably face issues with end-users or project houses, including project cost control, restricted headroom for samplers in plant layouts, and a lack of knowledge in certain quarters. These all have a potentially negative effect on the final outcome of a proposed sampling solution or implemented project. In reality, what is intended by all parties and what is ultimately installed are at times very different, with undesirable consequences for all concerned. Against this challenging background, there are, however, a number of instances where intent and implementation are complementary, with very satisfactory results. Keywords sampling, mechanical samplers, design, installation, sampling theory.

Jan 1, 2014