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By Morris Muskat

ALTHOUGH the problem of well spacing is one of the most important involved in the production of oil, it must be considered at the present time as still subject to further development. The published literature on this question is so voluminous that we cannot enter here into a review of it, except to refer to the recent papers by L. L. Foley1 and E. A. Stephen-son,2 where other references are cited. However, a decisive and conclu-sive answer to the problem of well spacing in any general form does not seem to have been developed. And while we shall be unable to present the desired solution in the present paper, it is nevertheless felt that the material to be given here not only provides the physical ground work for the ultimate solution, but shows qualitatively the essential factors that enter the well-spacing problem. Field studies of the well-spacing problem, in which the ultimate recoveries from different fields with different well spacings have been compared, have generally suffered from the lack of knowledge as to the similarity of the inherent characteristics of the producing reservoirs being compared, such as the sand volumes, the sand porosities, the sand permeabilities, the original reservoir pressures, the presence or absence of gas caps, the presence or absence of effective water drives, and the economic limits of production rates at which the various fields were considered to have yielded their ultimate recoveries. Certainly no one who is evaluating originally the economic significance of any oil reservoir would deliberately ignore these phases of the problem. And it is equally certain that no one would reasonably expect the ultimate recoveries from two reservoirs, even with the same well spacing, to be identical regardless of these other factors. More reliable results might be expected from comparisons of the recoveries obtained from different leases with different well spacings, but producing from the same reservoir sand. Unfortunately, however, even conclusions for such studies may be subject to serious errors. The reason simply is that however much one may insist that an operator is entitled only to the oil immediately underneath his surface acreage he will nevertheless drain the surrounding properties as long as his reservoir

Jan 1, 1939

By Zheng Shuangying

The vibration effect of the buried oil pipeline caused by tunneling blasting affects the pipeline safe transportation, tunnel construction schedule and its construction cost. The dynamic response characteristic of the buried pipeline under blast loads is the foundation of designing blasting scheme as well as the prerequisite to pipeline safety. Taking the blasting engineering of Xiannvyan tunnel passing through a buried oil pipeline of the high-speed railway from Xi’an to Chengdu as the background, according to the space relation between tunnel and pipeline as well as the charge structure of V-cut blasthole, the 3D non-linear dynamic finite element model of tunnel-pipeline was established in the light of the equivalent explosive. The vibration response of the ground surface over pipeline resulting from V-cut blasting was simulated by LS-DYNA finite element program. Comparing with the measured vibration velocity waveforms in site, the accuracy and reliability of the numerical model are well verified. On the base of the simulation method, the coupling dynamic response characteristic between buried oil pipelines and soil was further studied and the Von-Mises stress distribution of pipeline wall was obtained. The safety of buried oil pipeline was quantitatively analyzed through the inside stress data of pipeline given by the simulation calculation above. The analytic results show that the maximum vertical vibration velocity of pipeline on the interface between pipeline and soil is 1.62~5.07 times as large as that of soil. When the buried pipeline is located over the tunnel and 13 m (42.6 ft) away from tunnel, the maximum vertical vibration velocity of ground surface caused by V-cut blasting with charge weight 17 kg (28.6 lb) is 3.17cm/s (1.25 in/s) and the vertical peak vibration velocity of pipeline top is about four times as the ground location directly above the pipeline. Meanwhile, the peak dynamic stress of the buried pipeline caused by blasting vibration is only 2.35% of the allowable stress of steel pipeline. The maximum superimposed stress of the blasting dynamic stress and the hoop stress produced by the pipeline internal pressure is 242.56 MPa (35 180.36), which implies that the buried oil pipeline is completely safe under the conditions of the given tunnel blasting scheme.

Jan 1, 2015

By Edwards Wichers

The purpose of this paper is to set forth the matters of principal interest in connection with work done in the past few years on the purification of the metals of the platinum group, including the study and modification of methods already in the literature and the development of new procedures. For the most part, the results will be given in summary form, reserving the publication of detailed data and directions for a forthcorning paper to be issued by the Bureau of Standards. In recent years increasing interest has been shown in the preparation of the pure platinum metals, both by those concerned with the manufacture of the metals and their alloys for scientific and industrial purposes and those who are engaged in the study of the chemical or physical properties of the elements. The purification of the metals usually has been regarded as a matter so involved and difficult as to require the attention of specialists. It is hoped that this paper will show that any of the metals can be prepared in any desired degree of purity by relatively simple straightforward chemical methods. For the most part, it is thought that the methods given are suitable for small-scale refineries as well as for the laboratory; also, that they will bring the time required for the purification of any of the metals within reasonable limits. The new procedure suggested for purifying platinum should prove to be much shorter than any methods described in the literature. Treatment of Platinum Ore As is well known, the principal source of the platinum metals is a mixture of several native alloys of the metals, found chiefly in naturally concentrated deposits in stream beds or alluvial material. Without attempting to enumerate all of the minerals present, it may be said that the concentrated ore from such sources contains all of the six platinum

Jan 1, 1928

By Willard P. Ward

The numerous direct processes which have been patented and brought before the iron-masters of the world, differ materially from that now introduced by Mr. Wilson. After a careful examination of his process, I am convinced that Mr. Wilson has succeeded in producing good blooms from iron-ore, and I think that I am able to point out theoretically the chief reasons of the success of his method. Without going deeply into the history of the metal, I may mention the well-known fact, that wrought-iron was extensively used in almost all quarters of the globe, before pig or cast-iron was ever produced. Without entering into the details of the processes by which this wrought-iron was made, it suffices for my present purpose to say that they were crude, wasteful, and expensive, so that they can IE employed to-day only in a very few localities favored with good and cheap ore, fuel, and labor. The constructiou of larger furnaces and the employment of higher temperatures led to the production of a highly carbonized, fusible metal, without any special design on the part of the manufacturers in producing it. This pig-iron, however, could be used only for a few purposes for which metallie iron was needed; but it was produced cheaply and with little loss of metal, and the attempt to decarbonize this product and bring it into a state in which it could be hammered and welded was soon successfully made. This process of decarbonizatioa, or some modification of it, has successfully held the field against all, so-called, direct processes up to the present time. Why ? Because the old-fashioned bloomeries and Catalan forges could produce blooms only at a high cost, and because the new processes introduced failed to turn out good blooms. Those produced were invariably "red-short," that is, they contained unreduced oxide of iron, which prevented the contact of the metallic particles, and rendered the welding together of these particles to form a solid bloom impossible. The process of puddling cast-iron, and transforming it by decarhonization into wrought-iron has, as everybody knows, been in successful practical operation for many years, and the direct process referred to so closely resembles this, that a short description of the theory of puddling is not out of place here.

Jan 1, 1884

By O. Jay Myers

THE war effort has furnished the necessary impetus for better magnesium foundry practice. Four or five years ago, there were but a few formulas in general use for cores and mixtures for magnesium castings. Certain sands, binders, and inhibitors were specified and the proportions of these materials in each mixture were maintained between very narrow limits. As more and more war industries entered the field, much research was carried out and methods and practices were improved. Magnesium founding is still in a state of flux; therefore it is not uncommon to find one foundry spraying inhibitors on its cores, and another foundry using sand mixtures with incorporated protective agents. The basic core or dry-sand mold mixture for magnesium in use today is compounded with sand, core oil or resin binder, cereal, and moisture. Core oil or resin binder are added for baked strength while the cereal binder and moisture are for green strength. The normal mixtures (based on the weight of the sand) contain from 0.5 to 1.5 per cent of both cereal binder and core oil, and the moisture content varies between 1.5 and 5 per cent. The ratio of core oil to cereal binder varies from 60:40 to 40:60, while the correct amount of moisture depends upon the method of coremaking. PROTECTIVE AGENTS In all magnesium practice, protective agents are used in conjunction with the core and molding sands to prevent oxidation of the metal. The use of these inhibitors is not novel, but publications covering this field are not entirely adequate. Beck1 says Magnesium alloys decompose water to form magnesium oxide, hydrogen being liberated in the process (Mg + H20 -+ H21 + MgO). This reaction results in the blackening of the skin and the appearance of areas of porosity on the casting surface, the cavities of which are filled with a grey oxide powder (these are termed `burns'). Although sand cores for magnesium castings are thoroughly dried during the baking cycle, burning will take place on the castings unless the metal is protected properly. This type of burning is more difficult to define than the "water-magnesium" reaction cited by Beck. A possible explanation may lie in the following equation: 2Mg + 02 -s 2MgO Here, the source of the oxygen is not water, but the air in the mold cavity, together with the chemically combined oxygen in the core-binding media. Generally, two methods are used to prevent this reaction from taking place.

Jan 1, 1945

By W. Dan Hausel

More than 220,000 diamonds have been found in the United States that range from microdiamonds to 40.42 carats in weight (Table 1). Some reports suggest diamonds weighing more than 100 carats have also been found in this country, although these reports have not been verified. The source of most of the diamonds in the United States is a group of kimberlite pipes, dikes and blows in the Colorado-Wyoming State Line district and a group of lamproite pipes in the Murfreesburo, AR area. Other areas where diamonds have been found include the Great Lakes region, the Pacific Coast and the southern Appalachian Mountains. The latter two regions are generally not considered favorable for diamond deposits. This is based on exploration models. They suggest commercial diamond deposits will be restricted to kimberlites emplaced in Archean cratons and to lamproites emplaced in Proterozoic mobile belts accreted to the cratons.

Jan 1, 1995

By C. O. Dale, W. J. Rundle

THE upper Mississippi Valley zinc-lead area was the first major lead producing section in the United States. The lead ore, found near the surface in crevices, was relatively pure galena that could be smelted directly into lead, at first in log hearth furnaces and later in more efficient blast type furnaces. French Canadian fur traders encouraged the Indians to mine the lead ore and showed them how to smelt it into lead that had a high value for bullets.1 Nicholas Perrot found lead ore on the Mississippi River bluffs near the junction of Wisconsin and Illinois and in 1690 established a trading post on the Wisconsin side of the river opposite the present site of Dubuque, Iowa.2 Shortly after 1720 discovery of Mine La Mott in Missouri diverted considerable attention from the Upper Mississippi area. Mining continued on a desultory basis with operations concentrated in the Galena, Illinois-Dubuque, area. In 1740 at least 20 miners were at work in the Fever River area around Galena and are reported to have shipped 2500 70-lb pigs of lead to Kaskaskia in 1741.3 Julien Dubuque established a mining and smelting operation in 1790 near the city that bears his name 'and was granted sole right to exploit the mining operations on the lands of the Sauk and the Fox Indians. He is reported to have produced 30,000 70-lb pigs of lead in 1805. Following the death of Dubuque in 1810 the Indians refused to let the white miners enter their lands, and little was done on the Iowa side of the river until the Indians were removed by treaty with the United States government in 1832.4 Early mining was entirely for lead but as the crevices were followed down, increasing percentages of zinc sulphide and zinc carbonate were encountered and at first discarded. Later a market became available for the zinc ores, and hand jigging devices were made to separate the lead," the zinc, and the rock or waste materials. The first record of zinc production from -the area is for 1860. Production of zinc passed that of lead before 1900, reached a peak of 64,000 short tons' in 1917, fell off rapidly and continually to about 2000 short tons in 1938, and since 1940 has ranged from 11,000 to 19,000 short tons. Lead has been of considerably less importance since 1900, and at present only about 10 pct as much lead as zinc is produced. Practically all of the zinc ore has come from orebodies that are rather flat and wide with, considerable length as compared to width. Most of the early lead came from the crevice type deposit, but present production is from the predominately flat zinc orebodies. The Graham-Snyder orebody, scene of Eagle Picher operations, is practically all zinc with little or no lead being recovered. Marcasite, present in varying amounts, makes production of finished concentrates by gravity separation impractical. Satisfactory lead and zinc concentrates have been produced since flotation was introduced in the area in 1927. An acid recovery plant was operated for about 20 years after World War I, but it has been dismantled, and no recovery of the iron sulphides in the ores of the district is being made at the present time. In June 1950 there were three companies operating mines and mills, Tri-State Zinc Co., Calumet & Hecla Consolidated Copper Co., and Eagle Picher Mining and Smelting Co. The Vinegar Hill Zinc Co. had completed a shaft at a new orebody and had started to develop the mine which will supply the Cuba City mill. The Cuba Mining Co. was holding the Andrews Mine inactive. The Dodgeville Mining Co. was not operating but was exploring for additional reserves. Several small mines were selling ore to the Eagle Picher mill. A general area map is given in Fig. 1. The Eagle Picher Mining and Smelting Co. entered the area in 1946 with an active exploration campaign. Leases on a block basis were secured for the area south from the Wisconsin-Illinois line near

Jan 1, 1952

By M. R. Geer, H. F. Yancey

WITH the exception of pneumatic processes and ii few special beneficiation methods of comparatively limited application, all mechanical coal-cleaning and mineral- dressing processes involve the admixture of solid particles with a liquid, generally water. Upon completion of the beneficiation process the solids must be reclaimed from the water. With coarse particles separation of solids from water is accomplished readily by the simple expedient of screening, but recovery of fine solids presents a much more difficult problem. Thickening and dewatering are practiced so generally, both within the mineral industry and else- where, that they have been the subject of study through the years and a number of processes for making the solid-liquid separation have been developed. Dorr-type thickeners have been standard equipment for many years, and more recently driers employing centrifugal force have gained in popularity. 1 A cyclone device employed to thicken the loess suspension is a novel feature of the loess heavy-medium coal-cleaning process developed by the Netherlands State Mines in the thirties. The cyclone thickener was first mentioned by Driessen2 in 1939 in a paper describing the loess process and has been the subject of two more recent reports by the same author.3 The cyclone does not differ greatly from cyclone dust collectors used in this country for years, except that it is operated wet rather than dry. Advantages of the cyclone over other thickening devices are its simplicity of construction, high capacity, and the fact that, having no moving parts, it is simple and inexpensive to operate. The Bureau of Mines became interested in the cyclone after one of the present authors observed it in operation in the Netherlands in 1945. The first experimental work with the cyclone conducted by the Bureau of Mines was an investigation of the unit functioning as a heavy-medium cleaner for fine coal-a use for the cyclone that was conceived long after it had been perfected as a thickener. The results of this investigation were published last year.4 The present investigation deals exclusively with operation of the cyclone as a thickener. OBJECT AND SCOPE OF INVESTIGATION Although the cyclone thickener has been dealt with in three reports by Driessen, its use as a thickener was not the principal subject of any of these reports and therefore neither the cyclone itself nor its operation was described completely. The design of the cyclone was described only in a very general way, only limited operating results were given, and virtually nothing was disclosed about the influence of the various possible operating variables. Moreover, the Netherlanders apparently had employed the cyclone exclusively for thickening loess and had not employed it on coal slurries. One English colliery has used a cyclone to thicken coal slurry,5 and as it appeared that

Jan 1, 1948

By E. Gilpin

The following notes may serve to bring before your Institute an idea of the iron-ore resources of Pictou County. Enough work has been done to permit an estimate to be formed of their quality and probable extent. As yet the systematic mining and smelting of ironore in Nora Scotia is confined to the operations of the Steel Company of Canada, in Colchester County. Although the locality I am about to describe appears, in many respects, well adapted to iron smelting, etc., no attempts have yet been made to begin work. Nora Scotian capital is more readily turned to lumbering, fishing, and shipping ventures; and such an investment appears equally foreign to the rest of the Dominion. I need not, however, go further into this part of the subject, and can only hope that my notes may prove serviceable as indicating a probable field for future development. The accompanying map shows the position of the harbor of Pictou relative to the coal and iron-ore fields, and to the railways which intersect them. The branch of the Intercolonial Railway, running from Truro to Pictou, forms the western boundary of the iron-ore district, which extends beyond the point where the New Glasgow and Cape Breton Railway crosses the French River. The iron-ore district may be roughly described as a triangle formed by the ore-outcrops and the two railways, the former making the base, and the latter the sides of the triangle, the apex resting on the coal-field at New Glasgow. The drainage of the country is toward the Gulf of St. Lawrence, through the Middle, East, Sutherland's, and French rivers; and the surface is undulatory, seldom exceeding two hundred feet above the sea-level, except in the district lying between Glengarry and the upper waters of the French and Sutherland's rivers, where a maximum height of about five hundred feet is reached at several points. Geologically speaking, the district embraces two divisions, the Carboniferous and the Silurian, the latter resting on strata provisionally considered to be of pre-Cambrian age. As no geological

Jan 1, 1886

By Eben E. Olcott

The Mine.-For some years attention has been drawn to the copper deposits of the Appalachian range of mountains, and especially to those in that portion crossing the corners of Virginia, North Carolina, and Tennessee. Certain it is that in many places in this locality available deposits of copper await the miner, and one after another are being opened and worked. The parts of these three States alluded to are but sparsely settled, and communications are insufficient to meet the demand for transportation. Railroads are wanted, as the existing wagon roads are unfitted for heavy hauling; these circumstances increase very much the difficulties in the way of mining enterprises. Notwithstanding this, the success of some of the mines of this section is an established fact, and Ducktown has for some years held a high rank among the copper-producing localities of the United States. Of all these deposits, however, none is more interesting or more deserving of attention than the one now under consideration. The works of the Ore Knob Copper Company have been energetically pushed forward, since the reopening of the mine, in the spring of 1873, by Mr. J. E. Clayton, the superintendent and one of the chief owners of the property, and if one thing more than another can insure success it is the combination in this gentleman of rare business capabilities with the deepest personal interest in the pros¬perity of the undertaking. The copper vein -at Ore Knob* is a clearly defined fissure traversing the gneissic rocks of Pre-silurian age in a direction 61° east of north. * The reader is referred to a paper by Dr. T. Sterry Hunt, in the second volume of the Transactions of the Institute, on the "Ore Knob Mine, and some related Deposits," pages 123 to 129.

Jan 1, 1875

By Yuhe Tang

High Gradient Magnetic Separator with Horizontal Magnetic Line is a new type High Gradient Magnetic Separator product. It has many specific advantages, such as water-air joint discharging technique, double pulses pulp dispersion technique, multi-magnetic gradient for collecting matrix with different diameter rods, better discharging rate with the especial matrix dispose, high separating accuracy and wide applicability. In this paper, the author makes a description of High Gradient Magnetic Separator with Horizontal Magnetic Line, and puts its emphasis on analyzing industrial production data using high gradient magnetic separator with Horizontal Magnetic Line to separate weakly magnetic minerals. It is found that as the rougher for weakly magnetic minerals separation, High Gradient Magnetic Separator with Horizontal Magnetic Line has more stable metallurgical performance and cheaper running costs than other types of High Gradient Magnetic Separator when the properties of the ore change greatly and there is in the case of embedded fine particle size distribution. Keywords: high gradient magnetic separator, self cleaning technology, horizontal magnetic line, water air discharging technique

Sep 1, 2012

By H. R. Froning, R. O. Leach

In wertability alteration flooding, a chemical agent is rnoved through a reservoir by the flood water to increase oil recovery by decreasing the degree of wetting of the rock by the oil. Substantial amounts of the chemical may be lost during movement through the reservoir. The extent of the loss, and therefore the economics of the process, depends in some cases on factors which are difficult to reproduce in the laboratory. Therefore, a short-duration, low-cost field test method is needed to permit evaluation of chemical requirements under actual field conditions. This paper describes a small scale rest conducted at a single well for measuring chemical requirements, thereby giving a more reliable evaluation of this important factor in the applicability and economics of the process. In the rest a small wafer slug containing the chemical agent and a nonadsorbed tracer is displaced into the reservoir by a known volume of wafer. The well is then placed on producrion. Chemical loss per barrel of pore volume contacted is calculated from [he fractional recoveries of the agent tested and the nonadsorbed tracer. The method has been used to determine within the actual reservoirs the chemical requirements for both a sandstone and a dolomite reservoir. Several chemical agents are potentially available for wettability alteration flooding, although none is universally applicable. For some applications of the method, chemical costs per barrel of additional oil recovered can be substantially less than one dollar. INTRODUCTION Wettability alteration flooding provides a means of increasing oil recovery from reservoirs by decreasing the degree of wetting of the rock by the oil and increasing the displacement efficiency of the flood water. Earlier studies demonstrated a relationship between oil recovery during waterflooding and the degree of wetting of a rock surface by an oil. The application of wettability alteration flooding to the Harrisburg field of Nebraska provided a field test' of this recovery process. Subsequently, additional laboratory and field tests have developed additional procedures for evaluating wettability alteration flooding, and have indicated where the process may be applicable. Applicability of this process to specific reservoirs is determined by a progression of tests to determine sus- ceptibility of the reservoir to alteration of its wettability, to indicate the degree of recovery improvement and to estimate the amount of chemical required to process the reservoir. The economics of applying improved oil recovery processes depends not only upon the degree of improvement in oil recovery achievable by the process but also upon the process costs and the timing of the income and the investment. Emphasis in this paper is on the expenditure aspects of the process. The work reported in this paper indicates that the chemical investments required for wettability alteration flooding are substantial. For evaluating the economics of a potential flooding application it is imperative that a sound estimate of the chemical requirements be made for the reservoir. Generally, true reservoir conditions are not adequately simulated in laboratory chemical propagation tests. Because of wide well spacings, many years might be required to obtain chemical propagation data from conventional pilots or inter-well tests. Consequently, n short-duration, low-cost method is needed to determine chemical requirements in the field. The potential applicability of wettability alteration flooding is discussed, as well as the economics of wettability alteration with respect to the inherent and imposed restrictions on the timing of income and investments. DETERMINATION OF CHEMICAL REQUIREMENTS In the process of moving a chemical bank through reservoir rock, some of the chemical agent lags too far behind the flood front to be effective or is otherwise lost to the reservoir system. The extent to which these losses occur overshadows the reductions in chemical concentration due to diffusion and to mixing with the reservoir fluids. Experience indicates that almost without exception, chemicals which induce a wetting change undergo either sorption reactions or chemical reactions with mineral constituents of the pore surfaces. Other reactions may occur between the added chemical and the reservoir oil and water. Even in limiting consideration to reactions of the relatively inexpensive inorganic salts, bases and acids, the reactions may be exceedingly complex. Reservoir pore surfaces consist of more than silica in sandstone reservoirs, and more than calcite or dolomite in carbonate reservoirs. Many mineral species are present, each exhibiting specific tendencies to react with an injected chemical. The reactions which occur can consume enough of the agent to have an important effect on economics. These reactions can cause a change in pH of the chemical bank, or may remove some of the active chemical by precipitation, adsorption or reaction to form a new chemical which may or may not be effective in

By K Biegaj, S C. Dominy

A high-nugget effect and presence of coarse gold characterises many styles of gold mineralisation. The effective sampling of these deposits is often difficult because of the relatively low concentrations involved and erratic nature of the gold or other minerals. Geometric and/or metallurgical complexities often compound this effect. Underground development, in-fill drilling and bulk sampling/trial mining are generally required to delineate Ore Reserves. Similarly expensive definition strategies often apply to surface mining in complex orebodies of gold and other minerals, including precious stones. Development, particularly winzing is a historical technique that was used to gather geological, grade and metallurgical data during underground and near-surface exploration. It permits access to the mineralised structure below the surface datum to determine viability. Winzing has always been considered an arduous and dangerous task. Modern winzing technology has led to the development of the Mobile Supersucker – essentially a giant vacuum cleaner with underground and surface capabilities. By the elimination of shovel-loaded blasted winze material into a kibble and hoisting, this system permits safe and highly efficient winzing activities, and allows the collection of bulk samples for grade and metallurgical evaluation, as well as access to the mineralisation for geological and geotechnical mapping. Bulk samples from horizontal development have long been collected to help define mineable grade via pilot processing. However, when defining blocks below current development, there has been over-reliance on ineffective ‘small sample’ drill data. The Mobile Supersucker permits the development of winzes and off-winze sub-levels. These provide critical information to a mine technical team when trying to justify capital to go deeper or commence or deepen an existing open pit. CITATION: Biegaj, K and Dominy, S C, 2018. Lowering risk in complex mineralisation: application of mobile supersucker development, in Proceedings Complex Orebodies Conference 2018, pp 113–115 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By Rakesh Kumar, Rajabrahma K., A. K. Verma, V. Mukesh

"In this study, laboratory investigation as well as numerical investigation is carried out to ascertain the transition from one mode to another for Semi-circular bend setup. Laboratory investigation is carried by varying the span length (s/2R); crack length (a/R); notch angle (a); and notch thickness (t). The specimen consists of cement, sand and water mixture in a ratio of 1:1:0.5 by weight and are prepared as per the ISRM standards (2014). Tests are conducted by a servo controlled universal testing machine at a strain rate of 0.2 mm/ min. The results are collected in terms of failure load, crack mouth opening displacement (CMOD) and images of crack initiation and propagation.Image analysis of laboratory tested samples shows that crack initiates at the notch tip when the notch inclination angle is 0°. As the notch angle increases (i.e. 30° and 60°) the fracture begins to initiate behind the notch tip. The direction of crack propagation in front and back side of the sample is same for notch inclination angle is 0° whereas it differs more and more as crack inclination increases. The transition represents the change in mode of failure from mode I (0°), mode II (30°) and mixed mode I/II fracture (60°).Finite element method used to find the transition based on MTS failure criterion. The inclination of notch is varied like 40, 42, 44, 45, and 50 deg and FEM analysis shows that the transition from mode-I to Mode-II take place at 49 deg. The same procedure can be extended to find the transition from mode-II to mode-III."

Jan 1, 2015

By H. Nematollahi

The comminution laws The grindability of the ores or minerals is an important factor that could not be deduced from their mineralogical characteristics (Testut, 1958). Many theories have been proposed to determine the amount of work required in a comminution operation as a function of the nature of material, size and shape of the minerals before and after of comminution. The most important laws are proposed by Rittinger, Kick and Bond. According to Rittinger (1867), the work is directly proportional to the new surfaces produced during the comminution. Kick (1885) believes that the work needed to produce similar modification is proportional to the volume or mass of the material. Bond, during his 25 years of experience and research, reached to the conclusion that on the average the energy required for a known comminution is between the Rittinger's and Kick's laws (Bond, 1952). According to Bond's Third Theory, the work input is proportional to the new crack tip length produced during the particle breakage, and equals the work represented by the product minus that represented by the feed. The work input is given by the following equation: [111W = 1 Owi( FP FF(1)] where W is the The energy input to the mill, (kWh/st); F is the Feed size based on 80% passed, (µm); P is the Product size based on 80% passed, (µm); and W; is the Work Index, (kWh/st) Methods to determine the Bond Work Index Various methods have been proposed by Bond to determine the Work Index. There are some problems with the Standard Bond Grindability Test: •Requiring a special mill. •Requiring a relatively large amount of sample. •Being relatively time consuming and tedious. [ ] During the recent years, numerous attempts have been made to install faster and easier methods to determine the Work Index. A complete description of these methods is presented by Yap et al. (1982). Determining the Bond Work Index by a new size ball mill During the recent years, researchers at the University of Tehran determined the Bond Work Index, using the Anaconda simplified methods by its Denver 305- x 127-mm (12 x 5-in.) laboratory wet ball mill. The equation used to calculate the Work Index for the above mill containing 16.12 kg (35.5 lbs) of steel balls is as follow: [1 _ 1-1W;=0.54x [P [)(2)] In addition, an attempt has been made to determine the Bond Work Index similar to standard Bond ball mill procedure but by a different ball mill, smaller and in consequent portable and less laborious than the Bond ball mill. Method description Just as the standard Bond grindability test, this method is a locked-cycle dry grinding and screening process that is carried out until steady state condition is reached. Test equipment The test is conducted in a special ball mill, called the New Size Ball Mill (NSBM). The mill is scaled down with a coefficient of two-thirds from the standard Bond ball mill. It measures 200 x 200 mm (8- x 8-in.) inside (instead of 300 x 300 mm or 12 x 12 in. in Bond ball mill). Just like the Bond

Jan 1, 1995

Major underground gold mine developments are not common in Australia especially when they are totally owned and hence financed by a relatively small public company. Ballarat Goldfields Limited with its Ballarat East Project is such a company. Financing a $20m underground exploratory access programme in a poor economic climate places added importance on the quality of the project. Critical factors such as ore reserves, environment, planning and the development program are of immense importance in devising and implementing a workable finance package that satisfies both the shareholder and the project's needs.

Jan 1, 1990

By Ernest F. Burchard

A reconnaissance of the chrome and manganesel ore deposits of Cuba was made in the spring of 1918 by Albert Burch, representative of the U. S. Bureau of Mines, and the writer, representing the U. S. Geological Survey. The object of the study was to obtain authentic information for use of the United States Government as to the location, character, size, and availability of the Cuban deposits of the ores of these important steel-alloy metals. The Cuban Government courteously detailed Sr. E. I. Montoulieu, a mining engineer connected with the Treasury Department, to act as escort and associate throughout the work on the Island. Mr. George A. Wright, of Baracoa, Cuba, a minirng engineer especially familiar with the chromite deposits of Oriente Province, was a member of the party from Feb. 25 to Mar. 20. It was possible to visit most of the chrome-ore deposits that seemed to be of promise, but there was not sufficient time to visit all that were brought to our attention, some of which may have merit. Furthermore, no attempt was made to examine the extensive chromiferous iron-ore deposits of the Mayari, Moa, and Cubitas districts, as these deposits cannot be regarded as sources of chromium except indirectly. At the close of the field work the essential data concerning the quantity and quality of ore probably available for shipment during 1918 and 1919, in the event of the continuation of the European war, and of the tonnage of ore in reserve, were furnished to such Government bureaus as were interested, including the Shipping Board and the War lndustries Board, and as soon as chemical analyses of the chrome ores could be obtained, a press bulletin on the subject was published by the Geological Survey. In the present paper the engineering data and tonnage estimates contained in the unpublished notes of Mr. Burch have been freely used, and their helpfulness is hereby gratefully acknowledged. Many thanks are due Senor Montoulieu and Mr. Wright for their valuable work in the field; to the officials of the Spanish American Iron Co. and of the various other companies; and to individuals holding chromite claims, for courteously facilitating the work of the party.

Jan 1, 1920

By John Marsden, Mike Botz

A variety of modeling techniques can be utilized to forecast metal production at heap leaching operations. These approaches reflect a wide range of complexity, flexibility, time to implement, cost, and accuracy. For many operators, a spreadsheet-based modeling technique is attractive since the calculations are directly accessible, models can often be developed by site staff, and the results are generally easy to extract and interpret. The authors have developed a spreadsheet-based modeling technique that provides a high degree of flexibility, while still considering detailed operating information for ore properties, leach kinetics, scaleup factors, lift height, and in-heap metal inventories. The technique involves establishing kinetic leach curves for each ore type to characterize metal extractions, followed by application of separate metal recovery curves to define the rate at which leached metals exit the heap in pregnant solution, taking into account delays due to the in-heap solution inventory. At any point in time, the difference between total metal extracted and total metal recovered is equal to the in-heap inventory of the leached metal. This modeling technique is particularly useful for larger multi-lift heaps where delays in metal recovery are appreciable due to in-heap solution holdup. The technique is also applicable to sites with multiple heaps, leach cycles, and/or metal recovery plants (e.g., carbon columns for gold; solvent extraction for copper). This paper describes the modeling technique, including input data required and methods for defining kinetic leach curves and metal recovery curves. The technique is compared against an alternative spreadsheet technique using a simplified in-heap solution inventory calculation to forecast metal production, which has proven to be effective at a number of sites.

Sep 3, 2019

By J. Martinovic

The large proportion of gangue minerals present in platinum bearing ores in South Africa provides challenges to the flotation and downstream processes. In order to take effective measures to reduce their recovery in flotation, an understanding of the mechanisms and factors influencing their behaviour is needed. Typical gangue minerals are pyroxene, feldspar, quartz, chromite and talc. Of these, talc is a naturally hydrophobic mineral and although it is present in relatively small quantities, it has a disproportionate effect as it has a strong froth stabilizing effect, increasing the recovery of other gangue minerals by entrainment. Talc recovery is effectively reduced with the addition of polymeric depressants. Although the other gangue minerals are assumed to be hydrophilic and their recovery by entrainment is expected to follow the water recovery, there is some evidence that they may be activated by the typical reagent suites used. Reagents such as copper sulphate, added as an activator, and collectors are used to selectively induce hydrophobicity on the sulphides. It has been shown that some of these gangue minerals can be activated. This research work investigates whether inadvertent copper activation is mineral specific and evaluates the mechanisms and factors affecting the reversal of activation with the addition of the depressants using electrokinetic measurements, adsorption and microflotation tests. Results are presented that show that the selected minerals do respond differently and that the reversal of activation is dependent on mineral type, depressant type, dosage and ionic strength of the electrolyte.

Jan 1, 2005

By Warren N. Warhol

The mutual growth of the rare earth industry and the Mountain Pass Operations was no coincidence. It was the commercial availability of rare earths on a scale first made possible by the capacity of the Mountain Pass Operations that spurred research and development efforts toward new applications for rare earths. The first important demand on Mountain Pass was europium oxide for the activation of red phosphor for color television tubes in 1964. Since that time, other rare earths have become even more important, and Molycorp is continuing to supply an ever widening variety of rare earth concentrates and compounds. We enjoy saying that rare earths are not really rare, and that they are not earths, either. Of course, we are talking about the 15 metallic elements with atomic numbers 57-71, called the lanthanides, which occur in nature always together in very similar proportions. Their scarcity can be gauged by the fact that there is more cerium in the earth's crust than there is tin, and more europium than cadmium. The word "earths" comes from the early chemical term for oxide. The rare earths were discovered as oxides, and the term has persisted.

Jan 1, 1980