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By Joseph J. Zaluski, J. Steven Gardner, Marco M. Rajkovich

The telephone rings at 3:20 a.m. An exasperated voice on the other end says, “There has been a mine explosion at Mine No. 5 and we have not heard from three units of men.” Twenty-three minutes later, the phone rings again and another panicked voice says, “There is something wrong at the slurry impoundment, the pool level has just dropped five feet and we are trying to figure out what is wrong” Thirty minutes later, the mobile phone rings. An excited security guard says, “We have reports of thick black water running down the right fork and left fork of Straight Creek and both seem to be rising in the banks.” If this is not enough excitement, the mobile phone rings again. A stressed company official says, “I just heard a report that black slurry is running out of the portals of XYZ Co. No. 2 Mine, which is adjacent to our No. 5 Mine.” Is this all some kind of dream or nightmare? More importantly, though, if this happens, what do you do? Most people think: “It can’t happen to me.” But mine explosions do happen, slurry impoundments can rupture and creeks can flood with black water causing damage to others, including competitors. A mine’s response must be quick, cool-headed, calculated and effective. This article examines the issues, concerns and ramifications of this hypothetical disaster. The authors then present a systematic crisis-management response.

Jan 1, 2004

By E. P. Youngman

Titanium ranks as one of the more abundant elements, is widely distributed, and occurs in concentrated form in numerous deposits. This substance was discoveres 140 years ago; but despite the efforts of metallurgists and chemists to find a place for it in industry, only within the last 10 or 15 years has the increased use of titanium pigments provided any extensive outlet for titanium ores. Even to-day titanium is confined to a few highly specialized industrial applications. The metal itself is now quoted regularly in trade journale, but scarcely yet can it be said that the production or use of the metal. has progressed very far beyond the laboratory stage. Ferroalloys containing the element were largely used for a time, especially in connection with the manufacture of Bessemer steel rails; but as American rail- ways adopted open-hearth rails in preference to Bessemer rails, the demand for the alloys in the rail manufacture gradually dwindled into insignificance. New outlets for ferrotitanium have been found in the steel industry; and the production of titanium alloys, both in the United States and in Europe, has increased in recent years. By far the largest use of titanium at the present time, however, is in pigments. The manufacture of titanium white began in Norway, but at present the United States is the leading producer. One of the two companies now operating in the United States is also the leading factor in European production. Although titanium occurs, in many minerals, the principal commercial sources are rutile (the natural oxide, Ti02) and ilmenite (iron-titanium oxide, FeO. TiO2). The latter is a coal-black mineral, but it is the one used in the manufacture of the titanium white of commerce, as well as in the manufacture of ferroalloys and arc-lamp electrodes. Rutile, the natural oxide, is not pure white and, being less common in nature, costs more; it is, therefore, reserved for use in the manufacture of titanium chemicals employed in relatively small amounts in dye works and bleacheries and for sundry minor purposes. This paper summarizes the titanium industry, with special reference to its economic aspects. It is offered as a survey of current trade literature and as a digest of material in the files of the bureau and is presented in response to numerous inquiries from prospective producers as to ways and means of exploiting deposits. (At present, much of the ilmenite consumed in this country comes from overseas, principally from British India..). A forthcoming circular, devoted to deposits of titanium-bearing ores, deals with foreign and domestic sources of supply.

Oct 1, 1930

By M. M. Manamela

Paper written on project work carried out at the University of Pretoria in partial fulfilment of the requirements of the B Tech degree at the Tshwane University of Technology This work tested whether ore particle size affects the carbon-based pre-reduction of titaniferous magnetite. Pre-reduction is performed at a temperature of some 1100°C in a rotary kiln, in the Highveld Steel process. Laboratory isothermal reduction measurements were performed with ore-coal mixtures at this temperature, to test the effect of ore particle size. The results show that size does limit the degree of reduction for particles larger than 15 mm.

Jan 1, 2005

By Ed Cope

The newly discovered South Arturo deposit is a Carlin-type, breccia-hosted, oxide gold deposit located on the Dee Mine property at the north end of the Carlin Trend in Nevada. The Dee Gold Mine was discovered in 1981 by Dee Delamar, a Cordex geologist. The property was put into production by Rayrock Mines in 1984. During its 16-year mine life, the Dee Mine produced about 18.6 t (600,000 oz) of gold from oxide ore at an average production rate of about 1.24 to 1.55 t/a (40,000 to 50,000 oz/year). In October 1997, Bar-rick Gold Exploration acquired the right to earn a 60-percent interest in the Dee property from Dee Gold Mines through an exploration farm-out agreement. Barrick Gold Exploration began exploration activities on the property in 1998 and vested in its 60 percent operating interest in 2004. However, the discovery hole at South Arturo was not drilled until July 2005 from atop the historic mine dumps located 300 m (985 ft) south of the Dee openpit. The discovery hole (BD-72) encountered a cumulative 75.6 m (248 ft) of oxide mineralization grading 1.9 g/t (0.055 oz/st) gold beneath 260 m (855 ft) of dump material and post mineral Tertiary Carlin Formation volcanic and sedimentary rocks. Oxidation within the deposit extends to depths greater than 610 m (2,000 ft). The deposit has passed the prefeasibility test and is presently in the feasibility stage. Exploration is on-going to enhance or enlarge the known deposit. The current resource for the deposit stands at 40.4 t (1.3 million oz) of gold. The South Arturo discovery is an example of an historic mining property yielding a new discovery through the diligent application of area selection criteria of the model type and persevering when early results were generally negative. Barrick?s original exploration pro-grams on the property were focused on the discovery of deep, high-grade sulfide deposits that would likely be mined by underground methods. As it turns out, South Arturo is mostly oxidized and will be amenable to mining by openpit methods

Jan 1, 2008

By Peter Cain

The paper presents previously unpublished results derived from an unique interaction moitoring program conducted in the Sydney Coalfield of Nova Scotia. An abandoned, sealed longwall gateroad was re-entered and instrumented prior to extracting a longwall face 140 m below it. Instrumentation included piezometers connected to a constant head tank to monitor subsidence, and horizontally mounted extensometers to measure strains associated with subsidence. Survey levelling data was also collected. The monitoring results have allowed a number of significant conclusions to be drawn, all of which were either unanticipated or contradict current mainstream thinking. Firstly, interaction subsidence was less than anticipated. Secondly, the effects of rate of face advance on the development of the subsidence profile are evident. Thirdly, compressive strains are shown to remain in the subsided strata. Finally, strata response to undermining was almost immediate. The impact of these findings on the extraction of longwall panels beneath flooded workings in the Sydney Coalfield are discussed.

Jan 1, 1996

The metallogenic map of New Zealand shows the distribution of metallic mineral deposits, according to type and size, in relation to their geological setting. The major purpose of the map and accompanying 200-page monograph is to summarise the distribution, modes of occurrence and origins of the metallic mineral deposits of New Zealand. The map demonstrates the prospectivity of New Zealand for metallic minerals, particularly gold, silver, iron, and titanium. Information on each deposit is summarised in index tables based on major geotectonic units or deposit/commodity type. The mineral deposits are arranged and discussed in relation to tectonostratigraphic and tectonomagmatic units or terranes, under broad geotectonic divisions of the Paleozoic to Mesozoic Western Province, the late Paleozoic to Mesozoic Eastern Province, the mid Cretaceous to early Tertiary rifting phase, and the late Cenozoic Kaikoura Orogen. Regions or areas of marked concentration of mineralisation are recognised as metallogenic subprovinces or districts, namely: eastern Northland (Hg), the Hauraki Goldfield (epithermal Au-Ag-Pb-Zn-Cu), the west coast of the North Island (shoreline placer Fe), east Nelson (podiform Cr), west Nelson (porphyry Mo), the West Coast of the South Island (shoreline placer Ti), west Nelson-Westland (placer Au), Reefton (mesothermal Au-quartz veins), and Otago (placer Au and mesothermal Au-W quartz veins).

Jan 1, 1993

By L. J. Leach

Quench and tempered Cr-Mo plate steel was found not to contain a fully martensitic structure as a result of either slow slack quenching or insufficient hardenability at the cooling rates used. The resulting microstructure contains bainite in combination with martensite. It is necessary to examine the implications of bainite for the toughness of the final product. Loss of toughness arises primarily from the inter-lath carbides that typically form in upper bainite. An investigation into the effect of upper bainite in a martensitic matrix of a steel grade containing 0.17% C, 0.1% Cr, 0.54% Mo, and 20 ppm Bindicated lower toughness than in a fully martensitic structure.

Jan 1, 2013

By Charlie Wyche

In 1980, gold, silver, and pit and quarry construction materials were the principal minerals produced in the Dominion of Fiji. The combined value of these minerals totaled some $7.2 million,2 over 85% of all mineral production, Production of cement, sand and gravel, and quarry products continued to increase, but gold and silver production from Fiji's only operating mine declined slightly from the previous year's level. Mineral exploration has been carried out by U.S., Australian, British, Canadian, West German, and South African companies since the early 1960's, and a high level of activity was maintained throughout 1980. At the end of 1980, some 40 mineral prospecting licenses covering over 4,300 square kilometers were in force, and 19 applications were under consideration by the Mineral Resources Department. Total expenditures by mining companies on land base projects exceeded $6 million in 1980.

Jan 1, 1982

By D. G. Hattingh, A Els-Botes

"Considerable information is available on the factors influencing the iron-zinc reaction rate at 450° C of low carbon steels, in comparison there is a scarcity _of similar fundamental information of spheroidal graphite irons. This can be attributed to the more complex microstructure and ferrous alloy chemical analysis of spheroidal graphite irons. Hot-dip galvanizers have identified the complexity in controlling and predicting the thickness of the galvanized coating formed on commercial cast irons, which has serious financial implications for both the galvanizer and customer.Commercial hot-dip galvanizing has been in use for over 160 years and yet an elementary understanding of the dynamics associated with the hot-dip galvanizing of spheroidal graphite cast iron is still insufficient. To allow the. process to become a modem surface engineering technology, the fundamental aspects of the process must be thoroughly understood.When a clean iron or steel article is dipped into the molten zinc, zinc initially solidifies around the steel or iron. As heat is transferred to the article form the bath, this initial solidified zinc layer remelts and a series of iron-zinc alloy is formed by the reaction of the zinc with the surface of the article; on removal from the bath, some of the molten zinc is taken out on top of the alloy layers. At normal galvanizing temperature (450 °C), the reaction between iron and zinc is usually parabolic with time. The rate of reaction is rapid at first but then slows down and the coating thickness does not increase greatly if the article is immersed in the bath for longer times(1)."

Jan 1, 2000

By Eric E. Cather

Approximately 270,000 cu yd (20[0],000 cu m) of inferred subeconomic auriferous gravel resources were estimated in three Tertiary deposits in the Polk Springs study area (fig. 1 and table 1). These resources are exposed between tuff-breccia and lava flows of the Pliocene Tuscan Formation and Paleozoic or Mesozoic metamorphic rocks which suggests that although no deposits were identified in the other RARE II areas, they may be concealed beneath the Tuscan Formation. Difficulty in choosing drilling targets will make the likelihood of resource discoveries small. The development and production of these deposits would also be prohibitive under current economic conditions due to the thick covering of volcanic rocks. Recent stream gravels of Deer Creek in the Polk Springs study area contain enough gold to attract gold hobbyists; however, the stream gravels do not have sufficient volume to be considered a resource. Potential exists for additional auriferous gravels near the Occidental Mine in the Polk Springs RARE II area.

Jan 1, 1983

By A. B. Parsons

AT the outset, the authors of this paper desire to file a disclaimer and an, explanation. They have no inside information from occult sources; neither of them feigns clairvoyant powers in the slightest degree. It is true that they have indicated on be graphs an approximate trend for the consumption of seven important mineral commodities up to the year 1954. At best this is a risky business; the figures do not pretend to be any- thing more than reasoned conjectures that are predicated on an attempt to evaluate some of the more obvious of the many factors that are likely to have a bearing on the future.

Jan 1, 1937

By Arthur Notman

For the period January 1st, 1942, to January 1st, 1946, the American Bureau of Metal Statistics records the gold production of the world as 118,788,000 fine ounces. If we include 1946 at the same rate as 1945 (26,- 590,000), we arrive at a total of 145,378,000 fine ounces in the past five years . Included in these figures are estimates of Russian output at 4,000,000 ounces per annum for the five years, and 1,300,000 ounces per annum for Korea and Japan. The remaining 120,000,000 ounces represent the aggregate production from official reports of the other gold producing areas of the world, with the exception of the 1946 figures, as noted above. At $35.00 per fine ounce, this represents $5,188,230,000. According to the reports of the Federal Reserve System of the United States, on December 31st, 1941, the monetary gold reserves of the United States were $22,736,- 600,000 (at $35.00 per fine ounce) , while on October 31st, 1946 (latest available) , they had fallen to $20,402,000,000, a decline of $2,334,600,000. Adding this decline to the value of the new production for the five years, we have a total of $7,522,830,000, which has been absorbed by the rest of the world since Pearl Harbour, a rate of absorption of over $1,500,000,000 per annum. This has taken place at a rime when the advocates of purely managed currencies had convinced many people that gold performed no really essential function in the world's economy, and that we could get along perfectly well without it. It was pointed out that gold could not be eaten, it could not clothe our nakedness, it could not shelter us from storms, and, therefore, it was a non-essential, even though it could be used to settle international balances of trade. Apparently, the world as a whole still regards it as preferable to the paper promises of governments, however sound, relatively, they may appear. Actually, we have no way of measuring the true strength of this feeling, because the principal governments of the world have made it legally impossible for their citizens to own gold, except in the form of ornaments.

Jan 1, 1947

By R. R. Sayers

Carbon monoxide poisoning, as usually encountered, is an acute condition resulting from breathing atmospheres containing that gas. It is characterized clinically by headache, dizziness, weakness in the legs, increased respiration at first which later becomes irregular and depressed, collapse, unconciousness, and death; anatomically it is characterized by temporary changes in the red blood cells due to the combination of carbon monoxide with hemoglobin, and, in prolonged severe exposures, degenerative changes in various tissues of the body, especially those of the central nervous system. No race or nationality is immune or has a, special tolerance for carbon monoxide. From data at hand, it is known that both sexes are about equally susceptible. All ages are affected, but small percentages seem to have a more deleterious effect upon young animals and this is possibly true of children. Exercise, high temperature and humidity, and low oxygen content of en atmosphere increase the degree of poisoning for a certain concentration of carbon monoxide. Anything that lowers the physical fitness of a man, such as illness, overwork, or excesses of any kind, exaggerates the effects. More cases of poisoning from carbon monoxide occur in coal mines in the cold months of the year, because explosions take place more frequently during that period, also in homes where gas is used for beating purposes, and in garages from accumulation of automobile exhaust gases due to poor ventilation.

Jan 1, 1923

Triboelectric Charge and Separation Characteristics of Industrial Minerals The basic principles of triboelectric charge and separation of minerals and the factors affecting the entity of the charges developed on mineral surfaces are discussed and the surface pretreatment methods by which the electrophysical properties and thereby triboelectric charging and separation of minerals can be artificially altered/modified are reviewed. Furthermore, the triboelectricfication theory of materials is envisaged from the chemical concept of acid-base donor-acceptor and an attempt is made to correlate the physical concept of triboelectrification with the donor-acceptor properties. The triboelectric charge characteristics of the quartz, calcite and wollastonite mineral samples for different size classes were defined using different tribocharging medium. Based on the triboelectric charges acquired by mineral samples their energetic work function values are estimated. In addition, the main electrophysical properties, ie dielectric constant and electrical conductivity, of different size fractions of the mineral samples are measured and their donor-acceptor chemical properties were defined. A series of triboelectric separation tests were conducted to explore the possibilities for separation these mineral from each others. The results from the triboelectric charge and separation of the single mineral systems showed promising prospect in separating quartz, calcite, and wollastonite from each others. Finally, attempts were made to explore the possibilities to implement triboelectric charge and separation process to real ores. Promising results achieved when separation of calcite from silicate impurity was sought from a carbonate ore. A very high purity (99 per cent) calcite product was obtained at a recovery of 80 per cent. Interesting results were also achieved to concentrate wollastonite from a complex silicate ore containing quartz, different feldspars, wollastonite and other Mg-Fe silicates. In this case conditioning of the ore with salicylic acid at defined temperature and relative humidity was found to be essential to concentrate wollastonite. The outcomes indicate despite the fact that triboelectric charge and separation process has not been completely perceived, it pronounced to be an environmentally friendly and economically viable technique for minerals and wastes beneficiation. Being a dry beneficiation technique the process has special appeal, which must be explored further in particular for treating industrial minerals.

Sep 13, 2010

By Henry Kreisinger, WALTER T. RAY

General statement.-The briquetting tests conducted by the technologic branch of the United States Geological Survey had their beginning in the testing of coals and lignites at the Louisiana Purchase Exposition, St. Louis, Mo., in 1904. Briquetting tests were made at the fuel-testing plants at St. Louis, Mo., and at Norfolk, Va. Similar tests to be made at the experiment station of the Bureau of Mines at Pittsburg, Pa., form an essential part of investigations looking to the determination of the fuel value of the coals and lignites belonging to or for the use of the United States. The tests have comprised (1) the manufacture of briquets to determine the adaptability of different coals and lignites to the process and the merits of different binding materials; (2) physical tests to establish the fitness of the briquets to withstand weathering, transportation, and handling; and (3) steaming tests to prove the calorific value of the briquets in boilers of different types used by the Government, and, by comparison with the raw coals, the benefits to be derived from briquetting. Details of the tests have been issued in other publications. list of Government publications on fuel testing and briquetting is given at the close of this volume. Tests at Norfolk.-The fuel tests conducted at Norfolk included a detailed investigation of a number of Virginia and West Virginia coals that are bought by the United States Government for the Navy and for use in constructing the Panama Canal, and are extensively used by the merchant marine, manufacturing plants, and railroads. Through a cooperative arrangement with the Navy Department steaming tests of the coals were undertaken to determine the relative merits of the same coal when burned raw or as briquets in marine boilers. Preliminary arrangements were made between Joseph A. Holmes, then expert in charge of the technologic branch of the United States Geological Survey and now director of the Bureau of Mines, and Rear-Admiral Charles W. Rae, Chief Engineer of the United States Navy. The tests were made on board the U. S. torpedo boat Biddle, designated for the purpose, beginning December 6, 1907, and ending January 27, 1908. The coal used in these tests came from the Sewell and Beckley beds in the New River district of West Virginia. With the particular equipment used in the tests both coal and briquets were far. from smokeless; consequently the data of this bulletin are applicable only by analogy to parallel operation with a coal more nearly smokeless, but nevertheless applicable with much reliability. The possibilities of coals of different composition are indicated by the data to be published in a bulletin of the Bureau of Mines, wherein the present authors describe a number of tests in which only a very slight amount of smoke was emitted while burning raw coal from the Pocahontas No.3 bed, West Virginia, and briquets made therefrom at rates of combustion very much higher than any rates used in the torpedo-boat boiler. At a combustion rate of 120 pounds of the Pocahontas briquets per square foot of grate surface there was scarcely any smoke. It was the original intention to make a set of preliminary steaming tests alongside a dock (which tests furnish material for this bulletin) and to finish with a set of running tests at sea; but the running tests were never made, for lack of time and men.

Jan 1, 1911

Reduce the cost of modifying uranium well casings so that leaching solutions can pass through, but sand grains are blocked. Approach The well casing and surrounding cement are perforated at the mineralized zone by impinging them with high pressure water jets. How It Works A nozzle assembly is attached to a high pressure (15,000 psi) pipe and lowered into the well casing which typically is schedule 40 PVC (poly-vinyl chloride). The high pressure pipe line is extended down Into the casing until it reaches the mineralized zone. The upper end of the pipeline is then connected by a high pressure hose to the outlet of a 10,000 psi pump. Turning the pump on for 5 seconds causes a high velocity water jet to cut through the well casing and the surrounding cement. Figure 1 shows a high pressure pipe being installed in a well casing. Cutting small diameter holes in the casing allows the leachant to enter the casing and be pumped to the surface. However, the holes are small enough to prevent most sand grains from entering. Numerous holes are usually cut through the casing. The 3-nozzle assembly shown in Figure 2 cuts three holes, one above another.

Jan 1, 1978

By D. E. Pollock, J. A. Organiscak

Water sprays and water powered scrubbers have both been utilized in the mining and milling industry to suppress airborne dust. Unconfined water sprays operated at lower water pressures of ?689 kPa (?100 psig) can be very effective at wetting the mine product at the dust source and significantly reducing the amount of respirable dust that becomes airborne. However, unconfined waters sprays can be somewhat ineffective in actually removing airborne dust from the air. On the other hand, water powered scrubbers operating at higher water pressures of ?1,724 kPa (?250 psig) in physical enclosures or ducts have previously been demonstrated to be very effective in removing airborne dust from the air. These higher operating water pressures are uncommon in many mines and mills, so their use is limited. The National Institute for Occupational Safety and Health (NIOSH) recently investigated the performance of a lower-pressure, water powered inline series spray scrubber for removing localized airborne dust emitted at the source. Results showed noticeable improvements in airborne dust capture efficiency through the operation o f multiple inline series hollow cone spray nozzles within a round duct or pipe at the same water pressure as a single spray. Operating hollow cone spray(s) at higher water pressures noticeably improved airflow through the scrubber and yielded some additional scrubber efficiency improvements. Thus, in-line spray scrubber efficiency trade-offs were observed to be made by altering spray power components of water pressure and/or quantity (number of sprays). Results show that, on average, up to 0.23 and 0.32 m3/s (484 and 679 cu ft per min) of airflow at 0.81 and 0.69 dust capture efficiencies can be achieved with three 81° and 33°hollow cone inline series sprays, respectively, operating at 1,655 kPa (240 psig).

A field method combining solvent extraction and paper partition chromatography permits a simple and rapid semiquantitative estimation of gold in siliceous, argillaceous and sulphide ores. The method will facilitate the eyaluation of prospect samples in which the gold is too fine for separation by panning.Ethyl alcohol-hydrobromic acid mixtures are suitable for chromatographic development of the gold complex, and give clear reproducible definition of the gold zone. Substitution of commercial "methylated spirits" for the ethyl alcohol gives equally good definition, improving the potential of the method for field use.A batch of six samples in the range of 0·5 to 5·0 dwt/ton can be completed in two hours. The range may be extended by simple modification to higher or lower values.INTRODUCTIONIn a chromatographic method described previously (Lever 1958, Nevill and Lever 1959), gold from a standard volume of ore clamped between -plate glass was extracted by aqua regia on to the paper. After cautious drying the chromatogram was developed by an ethyl acetate-nitric acid-water mixture and gold was identified by spraying with stannous chloride solution. Sensitivity of the method in the low range was poor. The brown line obtained in the 1-3 dw/j ton range, caused by movement of gold in the reduced form, was not considered to be a satisfactory confirmation of the presence of gold. It was felt that the method would be improved by using a more elegant extraction and applying developing conditions which would produce a well defined purple line at all gold values. Iron was a limiting factor, and a method of eliminating its interference was needed.The method now developed overcomes these shortcomings, and gives a reliable result with a purple line for assay values of 0·5 dwtjton and over. Gold is dissolved from an...

Jan 1, 1964

Exploration work at the southern flank of the Mt. Coffin diapir has encountered three different types of copper ores: copper carbonate, largely malachite; secondary sulphides, mainly chalcocite replacing pyrite; and a primary arsenopyrite-tennantite-tetrahedrite-chalcopyrite association. The secondary copper ore is occasionally stratiform but mainly erratic at the contact between tillites and siltstones of the Tapley Hill formation.There have been two stages of primary mineralization.1. Arsenopyrite, tennantite, and tetrahedrite occur in siderite veins.2. Revival of the diapirism has caused fracturing and local brecciation of the rimrock and subsequently ascending solutions precipitated chalcopyrite. The chalcopyrite also partly replaced arsenopyrite, tennantite, and tetrahedrite.

Jan 1, 1972

JESSE L. JONES,* Pittsburgh, Pa. (written discussion?).-As the die-casting process is so very different in character from the process of making sand molds, it is often considered that entirely different methods of pouring, gating, venting, etc. should be used. There is really, however, no essential difference in the making of (lie castings and sand castings, and similar methods should be used in each process. In the matter of gating, the metal should be introduced at a central point, as nearly as possible, so that it will have an equal distance to flow from the point of entrance to the most distant points of the mold. This will cause a uniform rate of congealing of the casting and prevent streaks and cold shuts. The venting should be done in such a way that a free exit of the air in the molds can occur. It should be less difficult to take care of the venting of a die-casting mold than to vent an ordinary sand mold. In the case of a sand mold, the venting is left, to a considerable extent, to the judgment of the molder, and it is possible that no two molds will be vented in a similar manner. Further than this, after a vent has been made in a sand mold, it may become clogged by the sand and for this reason be inefficient. There is also quite a variation in the pressure of the metal entering a sand mold, due to varying heights of the pouring gate. In a die-casting mold these factors can be controlled more closely. The vents should be so disposed that the air in the mold compressed by the entrance of the metal may be able to leave the mold at a uniform rate and by exits located symmetrically. These exits are made quite small on molds at first, as they can he easily enlarged if necessary, and they are tapered so that a free flow is guaranteed without danger of the metal spurting out from the die. Uniformity of pressure of the metal as it enters the mold is very important and, as the pressure is mechanically applied, its control is not difficult. It is true that a sand mold has much less of a chilling effect on the metal poured into it than has the die-casting mold, but, outside of this point, there is a great similarity between the die-casting process and the process of making castings in sand folds. It is suggested that much would be gained by regarding these two processes as not essentially different.

Jan 4, 1919