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By R. G. Knickerbocker

THE copper smelter and refinery of The Messina (Transvaal) Development Co. Ltd., at Messina, South Africa, was erected in 1920 and 1921, but initial operations were deferred until late in 1922 on account of the collapse of the copper market in the interim. Because the anticipated production was to be only 20 tons of copper per day from a high-grade matte containing 60 per cent copper, and because the ore did not contain gold or silver in quantities sufficient to pay for separation from the copper bullion, it was decided to design the plant along lines quite different from the modern smelteries treating large quantities of sulfide ores carrying appreciable amounts of gold and silver. The plant was built, therefore, for the production of copper by the Nicholls-James process. By this method two-thirds of the copper matte produced was roasted in a Merton calciner and charged into a bath of the remaining one-third portion of unroasted matte in a reaction furnace. The original design was not only novel in providing for the Nicholls-James process, but also in comparison with new plants built elsewhere, because of factors inherent in the locality. Sources of supply for machinery were very remote; it takes three months after the placing of an order to accomplish delivery of machinery into Messina from the United States. Native labor was available at 30 to 40¢ per 8-hr. shift. These factors permitted plant design which provided no overhead cranes, no matte ladles, no slag pots or other usual mechanical means of transportation between departments. The design resulted in a compact simple plant with furnaces arranged close together and. terraced so as to provide for gravity transfer of molten material from one furnace to another and for manual disposal of products. Fig. 1 shows the relative location of furnaces. The three furnaces are parallel on successively decreasing elevations. A superimposed feed floor was provided above the furnaces. All three furnaces were provided with coal-dust burners served from a Bonnot system of coal-dust transportation, and the waste gases were discharged into waste-heat boilers.

Jan 1, 1932

By Edward Pesout

THE McGill smelter started operations in the year 1907. The smelter furnaces were fired with run-of-mine coal on grates until April 1911, when oil firing was introduced. Oil firing continued until April 1918, when the initial coal-pulverizing plant was started.1 EARLY PULVERIZING PLANT Various alterations were made to that plant during its operation, one of the more important being in connection with the system for delivering pulverized coal. In order to minimize coal-dust explosions and fires, the return portion of the main delivery line was eliminated in the year 1928. Thereafter coal-dust explosions and fires were greatly reduced. Pulverized coal was prepared at this plant primarily for the reverberatory furnaces, but for several years it was also delivered to the converting plant, roasters and power-plant boilers by a system of auxiliary fans and delivery lines. During the period March 29 to April 8, 1929, one reverberatory furnace was fired with pulverized coal produced by an Aero, type J, unit coal pulverizer with a rated capacity of 5 tons per hour. This machine actually pulverized its rated capacity but the product was too coarse. After certain regulations, a finer product was obtained but the pulverizer capacity decreased and this resulted in insufficient coal for efficient furnace operation. Table I gives a comparison of the average screen analyses of the pulverized-coal products from the impact-type unit pulverizer and the regular coal-plant installation. [ ] It was definitely proved that this size and type of unit pulverizer could not furnish sufficient coal of proper fineness to give smelting results comparable to that obtained with the regular coal-pulverizing plant. The coal from this unit pulverizer was so coarse that it did not ignite or burn properly and thus did not produce the proper heat for efficient smelting. During the latter part of 1929 and the early part of 1930, experimental work was conducted with a 7-ft. 0-in. by 48-in. Hardinge conical ball-mill coal-grinding unit, which was installed alongside a furnace in the reverberatory building. Results obtained from the test run indicated that this unit would furnish sufficient coal of proper fineness for good smelting.

Jan 1, 1945

The Jeffrey Company Opens Branch in Seattle The Jeffrey Manufacturing Co. of Columbus, Ohio, announces the re-opening of its Northwestern Branch Office at Seattle, Wash., and the appointment of Mr. Percy E. Wright, Consulting Mechanical Engineer, as District Manager for Oregon, Washington, Alaska, British Columbia and Alberta. Mr. Wright, who has been in the Northwest since 1910, and whose connection with the Jeffrey company dates back to 1902, has' had a wide and varied experience and training in the handling of the Jeffrey line which will enable him to be of great assistance to customers in solving their elevating, conveying and transmission problems. Trade Catalogs To a majority of the public, the name 'DuPont suggests military powder-munitions of war. The DuPont Products Book A-430 (April, 1916) lists 251 distinct commodities made. and sold by this company, many of which are far removed from destructive work. Mining men are fully cognizant of the need for explosives in constructive work, but they may be surprised to know that side by side with the powder and dynamite this company manufactures such peaceful articles as substitute leather, combs and collar buttons. The substitute for leather is Fabrikoid, varying in weight from a quality light enough for bookbinding to one heavy enough for trunks and automobiles, and the combs and collar buttons (with scores of other articles) are made from Pyralin. The book also contains a long list of chemicals, and a shorter list of special products and miscellaneous materials such as charcoal, wood flour and saltpeter. The Jeffrey Manufacturing Co. of Columbus, Ohio, making elevating, conveying, crushing, screening and power transmission machinery, has just issued its. latest Bulletin, No. 177, :featuring self-propelling wagon and truck loaders for handling crushed stone, sand, gravel, clinker, coke, etc. These machines are described as having a capacity of 1 to 1 ½ cu. yd. of material per minute, with power to load crushed stone maximum size pieces through 3 ½ -in. ring and to load trucks or wagons in 3 or 4 min. The self-propelling device is designed to enable one man to operate the loader as it is fed into the pile, and to move the machine about under its own power.

Jan 7, 1916

but, returning to South Africa, for the next two years he was assistant general manager of the Simmer Deep Gold Mining Co., at Johannesburg. In June, 1911, he returned to New Zealand as general manager and consulting engineer for the Consolidated Goldfields of New Zealand, at Reefton, which position he held at the time of his admission to the Institute in 1914. Early in September, 1915, he left New Zealand for active service in France. Corporal Sheppard B. Gordy Sheppard B. Gordy, born in Ansonia, Conn., in 1889, graduated from the Sheffield Scientific School in 1910 and with the degree of E. M. in 1912. He entered the employ of the Braden Copper Co. immediately on his graduation and remained with this company four years, working up through the various grades to assistant foreman and foreman to one of the individual mines. The last year he was in its employ, he acted as general mine foreman. He was for a short time with the Chile Exploration Co. and then went with the Andes Exploration Co. (Anaconda) and remained with the latter, doing mine exploration and development work, until he sailed for home in June, 1918, to give a more personal and active service to his country in her need. He declined a tender of induction into an officers' training camp, at the urgent request of Professor McClelland supplemented by Mr. Potter, because they demonstrated to his satisfaction that he could give more valuable service to his country in helping out with the aircraft production. Being within the draft age, in order to carry out this plan, it was necessary for him to be called by his Local Board and sent to camp. This call came Aug. 26. Two weeks before that time he had gone to Dayton, Ohio, to begin the study of aircraft production, and was sent by the Dayton Board to Camp Sherman, Chillicothe, Ohio, where he died of pneumonia on Oct. 9. Lieutenant Thomas Clarence Gorman Thomas C. Gorman, a lieutenant in the Second Tunnelling Company of the Canadian Engineers, was killed in France on Mar. 18, 1918. He was resting in his sleeping hut and was in the act of writing a letter when a bursting shell killed him.

Jan 1, 1920

By E. H. Wells, A. Andreas

New Mexico retained its position as the sixth largest oil-producing state for the year 1937 with a total production of 38,484,630 bbl. This was an increase of 11,680,184 bbl. over the 1936 production of 26,804,446 bbl., or a gain of 43 per cent. The production for Lea County during 1937 was 35,961,056 bbl.; for Eddy County, 2,136,251 bbl.; and for northwestern New Mexico (San Juan and McKinley Counties), 387,323 bbl. The average daily non-marginal well allowable for Lea County on Jan. 1, 1937, was 92 bbl.; at the close of the year it was 67 bbl. The average daily pipe-line runs were less than the allocations of the New Mexico Oil Conservation Commission, but slightly in excess of the state allowables recommended by the United States Bureau of Mines. The average daily production for the year was 105,437 barrels. The total number of completions in the state was 742, of which 638 were oil wells; 19 hydrocarbon gas wells; 5 carbon dioxide gas wells and 80 dry holes. Of the dry holes, 46 were in proven fields. Of these 46 dry holes, 13 were in the Artesia-Grayburg-Jackson-Maljamar area, Eddy County, two in the Getty Extension field, Eddy County, 11 in the Red Mountain field, McKinley County, three in the Rattlesnake field, San Juan County, and nine in the Aztec-Bloomfield area, San Juan County. There were only eight dry holes in the proven fields in Lea County. Southeastern New Mexico Lea County.—The Monument field was the largest producing field in Lea County, with 10,945,788 bbl., closely followed by the Eunice field with 10,927,929 bbl. The Hobbs field, formerly the largest producing field in Lea County, was relegated to third .place, with 7,292,522 barrels. Drjlling during the year closed the gap between the northern part of the Eunice field and the southern part of the Monument field. The wells in this area were relatively small, because of decreased porosity in the lime. The greatest activity in Lea County was in the Monument pool, with 199 completions, 197 being oil wells, one a gas well and one a dry hole.

Jan 1, 1938

The issue of flyrock is critical to the operation of all mineral extraction sites that use blasting. This paper takes a risk-based approach to identifying, analysing and managing the flyrock hazard. The basic cause of flyrock generation is a mismatch between the energy available and the work to be done. It should be noted that the energy available depends on the charge confinement. This mismatch can be caused by an abrupt decrease in rock resistance (geological weaknesses), overcharging, inadequate delays between holes and rows, inappropriate blast design and inaccurate drilling. The mismatch can come about from two sides; either too much energy (charge) for a fixed burden (work to be done), or insufficient burden (work to be done) for a fixed charge. The main mechanisms of flyrock generation are rifling, cratering, face bursting and secondary blasting. Each source mechanism has different characteristics in terms of vulnerable locations and each requires different control measures. However, all controls require a high level of quality control and assurance. A range of different approaches for managing flyrock risk and determining blast clearance zone dimensions are presented. A prescriptive consequence-based approach is discussed. A conventional risk matrix based approach is outlined with some innovation regarding controls rating and uncertainty ratings. A published semi-empirical approach is discussed. Two examples of quantitative flyrock risk analysis are presented; one involves bench blasting based on a published paper and the second is a cratering example developed by the author based on consulting projects. Finally, a stochastic approach based on published work is presented which simulates cratering superimposed on face bursting mechanisms. Also, a stochastic analysis undertaken by the author of the cratering example is presented. Effective blast emission management is required for two reasons; firstly to reduce and/or eliminate safety risks and secondly to manage public perception of blasting risks such as flyrock. The conclusion of the current research is that the wild flyrock risk can be estimated using existing techniques. Furthermore, both qualitative and quantitative risk management methods as discussed in this paper can be used for flyrock management for a given blasting situation. A combination of both is considered to be best practice.

Jan 1, 2007

By Yongxiang Yang, Yanping Xiao, Robert G. Harskamp

"Stricter environmental regulations demand for safer treatment and disposal of incineratior fly ashes. So far no sound technology and processes are available for a sustainable and ecological treatment of the waste incineration ashes, and only partial treatment is practised for temporary and short-term solutions. New processes and technology need to be developed for comprehensive utilization and detoxification of the MSW (Municipal Solid Waste) incinerator residues. The objective of the current research is to better understand the behaviour of the environmental harmful elements during low or high temperature treatment, and to find an optimum route for an efficient processing of the incineration fly ash. In the present study, the fly ashes including boiler ash and ESP (Electrostatic Precipitator) ash sampled from a MSW incinerator were washed with warm water, and the residues were dried and sintered or vitrified at high temperatures. The solutions from ash washing were analysed, and will be treated for salt extraction and purification. The ash residues before and after thermal treatment were also analysed. The results of vitrification and thermal behaviour were compared with those from the ashes without pre-washing. It was found that water pre-washing is an efficient way to remove certain water-dissolvable volatile salts such as chlorides, and thus the secondary emissions during vitrification could be reduced. INTRODUCTION The air pollution control residues from MSW incineration are classified as harzardous waste, including boiler ash, ESP ash and filter cake. The boiler ash is the firstly settled flue dust in the dust-collecting equipment under the boiler, the ESP ash is collected by an electrostatic precipitator in the second step, finally the flue-gas is further cleaned by the wet-scrubbers and residues are accumulated in the filter cake. Both the boiler ash and ESP ash are classified as hazardous materials, harmful to the environment due to the high concentrations of environmental hazardous elements. However, due to the different locations of the ash collection, the boiler ash has different compositions compared to the ESP ash, and is considered less toxic. Fly ash is generally toxic and with low bulk density, and has to be treated before final disposal. The current industrial practice is normally the landfilling after partial detoxification such as cement solidification."

Jan 1, 2008

By Robert L. Virta

An asbestos substitute is any material that replaces asbestos in a commercial product. There are many asbestos substitutes, each with its own unique physical and chemical properties. Substitutes can be inorganic or organic, fibrous or nonfibrous, and natural or synthetic. They also can be used as a direct substitute for asbestos or as a replacement product. Probably in no other field is the diversity of substitute materials so great. The concept of asbestos substitutes is not new. The first major effort to develop asbestos substitutes was undertaken by the federal government. The United States has always been dependent on foreign sources for strategic-grade asbestos, and during World War II, the government was concerned that these supplies would be cut off. Strategic-grade asbestos was critical in many electrical and thermal insulation applications (electrical insulation, battery plate separators, flame-proof boards, insulation for rocket components, etc.). A reliable supply of nonstrategic-grade asbestos also was required for general civilian and military applications, such as in brakes, clutches, and construction materials. The government not only initiated a major search for deposits containing strategic-grade asbestos, it also funded research on synthesizing asbestos in the laboratory and developing products that did not contain strategic- grade asbestos. These efforts, as well as those conducted by the private sector, generally were unsuccessful. In the late 1960s and early 1970s, a second major effort to develop asbestos substitutes began because the general public was concerned about the health threat posed by the release of asbestos fibers during the manufacture, use, repair, and disposal of asbestos-containing products. Strict regulations covering the mining and manufacturing sector already had been enacted because of the issue of occupational exposure. The issue then became environmental exposures. Environmental regulations were enacted, and through time they became more strict. The combination of increasingly strict environmental regulation, maturing of some asbestos markets, and liability issues prompted many manufacturers to discontinue asbestos product lines or search for asbestos substitutes. As a result, asbestos usage dramatically declined from the 1970s to the present (Table 1).

Jan 1, 1994

By Derek J. Fray, John Chipman

THE solubility of graphite in y-iron has been determined by several workers'12 with reasonable agreement. With the increasing use of more complex steels, it is necessary to understand more fully the thermodynamics of the austenite phase. The activity of carbon in a number of alloys is known but the maximum solu- bility of graphite has only been measured by Sohnchen and piwowarsky3 for Fe-Ni and Fe-Si alloys. Recently, Chipman and Brush reviewed the published data on the activity of carbon in binary and ternary austenite and also obtained expressions for calculating the solubility of graphite in Fe-Ni, Fe-Co, and Fe-Si alloys. On comparing the theoretically derived solubilities with the limited results of Sahnchen and Piwowarsky, it was found that the agreement for Fe-C-Si was excellent but there was considerable discrepancy for Fe-C-Ni and no data for Fe-C-Co. It was therefore decided to measure the solubility of graphite in a series of Fe-Ni and Fe-Co alloys. The alloy samples were made up by induction melting a high-purity master alloy under an inert atmosphere in an alumina crucible and drawing the molten metal into four-bore alumina tubes. Using this technique, it was possible to form alloy rods approximately 2 in. long and 1/18 in. in diam. Sixteen lengths of fine rod could be made without solidifying the master alloy. These were then allowed to cool under the inert atmosphere before being sectioned. The samples were packed in a graphite crucible with spectroscopic graphite powder, together with a piece of pure iron foil. Dry hydrogen, which had been saturated with isopropyl alcohol at room temperature, was passed over the crucible at 1000°C for 72 hr. At the end of the 72 hr argon displaced hydrogen in the reaction tube and the crucible was quickly pushed to the water-cooled end. The samples were thoroughly cleaned of the adhering graphite and analyzed. The pure iron samples always contained 1.5 0.02 pct C, which compares favorably with the data of smith2 and

Jan 1, 1970

By M. Hashemzadeh

The efficiency of water use is a top priority for the global minerals industry, especially in regions with limited freshwater supplies. In these areas, the freshwater shortage has prompted mining companies to search for alternatives to freshwater sources. Seawater has been proven to be a potential water source for mineral beneficiation and metal extraction processes. This study compares chalcocite leaching behavior with ferric chloride to that with cupric chloride. We carried out leaching tests with a highly pure chalcocite sample in jacketed reactors under fully controlled pH and solution potential. The effect of chloride concentration, oxidant concentration, and temperature on copper extraction was quantified in both cupric and ferric chloride systems. In the ferric chloride system, increasing ferric concentration showed a positive effect on the first stage of chalcocite leaching. In the second stage, increasing temperature markedly enhanced copper extraction. In the cupric chloride system, chloride concentration presented a considerable effect on both the first and second stages of leaching, while temperature had a remarkable effect only on the second stage. The findings of this study would be beneficial to mine operations aiming to replace fresh water with seawater for heap leaching of chalcocite. INTRODUCTION Mineral processing operations/plants are normally operated adjacent to mines which are often located in remote and arid area, such as northern Chile, southern Peru and Australia with limited access to fresh water (Liu, Moran, & Vink, 2011, 2013). Water scarcity in these areas has prompted mining companies to invest in sustainable technologies to reduce the water use and/or increase the water use efficiency. One of the current sustainable approaches in mineral processing operations is to replace fresh water with seawater. Seawater is now being increasingly used for mineral beneficiation and metal extraction processes (Hernández et al., 2015). Another application of seawater could be for heap leaching of copper secondary sulfides, mainly chalcocite. However, the high concentration of chloride ion in seawater may significantly affect leaching kinetics of copper sulfide concentrates and ores (Watling et al., 2014). Therefore, it is essential to develop a fundamental understanding of the leaching of chalcocite in chloride media.

Jan 1, 2019

By W. E. C. Coxe

Many of you who are interested in the manufacture of iron and steel, have no doubt heard of the "Wheeler process for combining iron and steel." Mr. Wheeler has formed a company, styled the "Combination Trust Company," whose business is to grant licenses for the use of this patent process in producing what he calls "iron-clad steel." It has been proposed to apply it in the manufacture of car or wagon axles, also to shafting, having steel cores or centres covered with iron; to tubes of steel with an inner and outer skin of iron ; to structural purposes, such as girders and beams; bridge and tie-bolts, where the strength of the iron and the rigidity of the steel would be desirable. In answer to a request from Mr. Wheeler, permission mas accorded him to make some experiments at the rolling mill of the Philadelphia and Reading Coal and Iron Company, at Reading, Pennsylvania, with a view to manufacturing some steel-headed rails. In making this kind of a rail two difficulties are encountered. If the iron is brought to the requisite heat to weld properly, the steel is likely to be burned; if the steel is cared for, to prevent burning, the several layers of iron are not brought up to the proper welding heat. Mr. Wheeler claimed that the steel slab covered with iron which he furnished for the head of the rail could net be injured by any heat to which it might be subjected in the ordinary course of heating the rail-pile. He claimed, also, that by this method the porosity, which he thought was characteristic of all solid rails of Bessemer steel, would be overcome. Four steel slabs were furnished for this experiment, being Bessemer steel of .61 carbon, made at the Edgar Thomson Steel Works, and covered with iron in one of the Pittsburgh mills. The slabs were in section seven inches wide by three inches thick, and the iron covering was one-eighth to three-sixteenths inch thick. Each slab was placed on a pile of iron made up in the ordinary way for a rail fifty-six pounds per yard and thirty feet long. The heating was under the personal direction of Mr. Wheeler, and

Jan 1, 1879

By W. Rostoker

IN the course of the development of the phase equilibrium diagram for the system Zr-Cr,' the structure of an as-cast allov having the composition ZrCr2 was analyzed and established to be isomorphous with MgZn2 (C14, hexagonal lattice, 12 atoms per unit cell). In a recent paper on the same system, Hayes, Roberson, and Davies' report for the ZrCr2 phase an isomorphy with MgCu2 (C15, cubic lattice, 24 atoms per unit cell). It appeared that this conflict might be resolved by assuming a high and low temperature modification for ZrCr2. That this was the case with the phase TiCr2 has recently been demonstrated by Levinger." Specimens of ZrCr2 annealed at 1200°, 1100°, 994", 900°, 834", 800°, and 700°C, respectively, and subsequently quenched were examined by X-ray diffraction analysis. It was successfully demonstrated that a transition from the MgZn, structure at lower temperatures to the MgCu, structure did occur at some temperature between 900" and 994°C. Table I lists the observed structures at the various annealing temperatures. In Table II, a summary of line spacings and intensities is given for each of the allotropic modifications. The first six lines of the MgCu2 structures have been located in the table to illustrate the close similarity between the patterns. Lattice parameters of the two modifications were calculated by a least squares solution of equations for interplanar spacings for a series of high angle lines. The results are as follows: MgZn2 type - c = 8.262 kX, A = 5.079 kX. MgCu2 type — a = 7.195 kX. It is interesting to note that TiCr2 behaves in reverse fashion yn that the MgCu, structure is the low temperature modification and the MgZn2 structure is the high temperature modification. References lR. F. Domagala, D. J. McPherson, and M. Hansen: This issue p. 279. 'E. T. Hayes, A. H. Roberson, M. H. Davies: Trans. AIME (1952) 194, p. 304; Journal of Metals (March 1952). 3B. W. Levinger: Trans. AIME (1953) 197, pp. 195-196; Journal of Metals (February 1953).

Jan 1, 1954

By Harlowe Hardinge, R. C. Ferguson

Laboratory and plant data covering 12 different operations show that lower than "standard" ball mill speeds increase grinding efficiency. In the case of high pulp-level mills, the gain is so great that the increase in capital cost of the larger lower speed mill will pay for itself in less than a year's time. THE object of this paper is to show the economic advantage of operating ball mills at relatively slow speeds. Although many operators know that grinding costs are reduced by operating mills at low speeds, they seldom do so for a variety of reasons. When capital is limited, first cost is of primary importance, and installation of the less costly, highspeed mill is favored. When materials are in short supply, as during a war period, capacity rather than economy is the primary consideration. Existing mills are then speeded up to provide the desired increase in capacity, and new mills are purchased without consideration of maximum grinding efficiency. When the mill speed is increased to secure more production, the increase in grinding costs is often obscured by the total benefit derived from the additional output. This increase in grinding cost is seldom recognized as being sufficient to be worth correcting. For these reasons one may be lead to the erroneous conclusion that slow-speed operation is only occasionally applicable. The effect of mill speed on grinding efficiency has been studied in laboratory tests."! The results of some of these tests are given in tables I and I1 and fig. 1. In these tabulations, batch tests using ore charges of 125 to 200 lb were considered comparable to high pulp-level operation and charges of 50 to 100 lb comparable to low pulp-level operation. For the high pulp-level operation, these tests indicate the existence of a maximum in efficiency for operation at a speed of 50 pct of critical, both for the soft (dolomite) and hard (chert) ore. In low pulp-level operation, a decrease in speed increases the efficiency of grinding dolomite; no maximum of efficiency appears in the range of speeds tested. The results with chert were inconclusive. If the performance of large mills is indicated

Jan 1, 1951

By Richard Moldenke

ONE of the little-known characteristics of cast' iron, which neverthe-less has an important bearing on results where accuracy in machining-is essential, is the ability of this material to ease up internal strains when. .allowed to remain quiescent for a more or less extended period of time. At seems as if the molecules in such a casting, by virtue of their "mobility,? can adjust their relative positions to an extent sufficient to overcome some of the existing stresses. The following instance will perhaps give a fair idea of the condition a casting may he in when just shaken out of the sand. A very large sheave-wheel, after shaking out, was taken' outdoors to be, cleaned and made ready for turning up. It was leaned against the side of the building, but before much could be done an arm tore apart with a loud report. Investigation showed that the sun had been shining on the upper rim, this adding a slight strain to those already existing within the arm and thus overbalancing the strength of the metal in tension. Had this sheave been kept under cover for a while, or at least until machined, the-strains., would have eased off sufficiently to allow the sun to look upon it without disaster. It will not be necessary to multiply examples. Every engineer knows the danger of water-hammer in pipe lines, particularly if the latter are of cast iron. Every mechanic knows, or should know, that it is not good to strike a fitting that is under steam pressure. It will be necessary to say a few words on the "internal- strains" in castings-the so-called "casting strains" we hear so much about. We all know that to get a casting reasonably true to the dimensions wanted requires a slightly larger pattern. The usual allowance for gray iron is 1/8 in. to the foot (1 cm. per meter) and ¼ in. to the foot (2 cm. per meter) for white iron (all dimensions). This reduction in length, breadth and thickness in a casting is erroneously called "shrinkage." It should be called "contraction," as for practical purposes. it is simply the difference .in dimensions of the casting red-hot and cold.

Jan 2, 1917

By W. E. C. Coxe

MANY of you who are interested in the manufacture of iron and steel, have no doubt heard of the "Wheeler process for combining iron and steel." Mr. Wheeler has formed a company, styled the "Combination Trust Company," whose business is to grant licenses for the use of this patent process in producing what he calls "iron-clad steel." It has been proposed to apply it in the manufacture of car or wagon axles, also to shafting, having steel cores or centres covered with iron; to tubes of steel with an inner and outer skin of iron ; to structural purposes, such as girders and beams; bridge and tie-bolts, where the strength of the iron and the rigidity of the steel would be desirable. In answer to a request from Mr. Wheeler, permission was accorded him to make some experiments at the rolling mill of the Philadelphia and Reading Coal and Iron Company, at Reading, Pennsylvania, with a view to manufacturing some steel-headed rails. In making this kind of a rail two difficulties are encountered. If the iron is brought to the requisite heat to weld properly, the steel is likely to be burned ; if the steel is cared for, to prevent burning, the several layers of iron are not brought up to the proper welding heat. Mr. Wheeler claimed that the steel slab covered with iron which be furnished for the head of the rail could not be injured by any heat to which it might be subjected in the ordinary course of heating the rail-pile. He claimed, also, that by this method the porosity, which he thought was characteristic of all solid rails of Bessemer steel, would be overcome. Four steel slabs were furnished for this experiment, being Bessemer steel of .61 carbon, made at the Edgar Thomson Steel Works, and covered with iron in one of the Pittsburgh mills. The slabs were in section seven inches wide by three inches thick, and the iron covering was one-eighth to three-sixteenths inch thick. Each slab was placed on a pile of iron made up in the ordinary way for a rail fifty-six pounds per yard and thirty feet long. The heating was under the personal direction of Mr. Wheeler, and

Jan 1, 1879

By W. R. Ingalls

THE bases of the work by the committee whereof I am chairman were (1) the abolition of extra-lateral rights and (2) the preservation of the maximum of the existing laws. The matter of extra-lateral rights had been under prolonged discussion among mining men and up to the time when our com-mittee began its work (in 1917) the expression of opinion in every way whereby it could be made known -and those ways were extensive-was only a little short of being unanimous that extralateral rights ought to be abolished. I have not observed important evidence indicating a change of opinion on the subject since 1917. ABOLITION OF DISCOVERY LOGICAL Now, when it be decided that extralateral rights ought to be abolished, there can not be merely a simple change to that effect, but it is found that consequential changes are necessary all the way through the existing laws. Abolition of extralateral rights implies abolition of discovery as a prerequisite to location, for otherwise there would be no legal means for locating claims on the dip of a vein. Quite apart from this consideration, abolition of discovery as a prerequisite to location is supported by other good reasons. Among these are the occurrence of orebodies with no exposure on the surface and which often are hidden at great depth. A prospector who has reason to suspect the occurrence of such an orebody must have legal means for the location of a claim within which to explore, and obviously he may. not be able to make any discovery on the surface sufficient to locate and hold legally such a claim under the terms of the law as it stands at present. As a matter of fact, discovery as a prerequisite to location was abolished by common consent many years ago, not only for the reasons that I have given here-inbefore but also for others. It is highly desirable to revise the mining law in this respect, so that it will conform to the conditions of practice and not require people to perjure themselves in making locations, even if it be for praiseworthy purposes.

Jan 6, 1922

By Edward Pesout

The McGill smelter started operations in the year 1907. The smelter furnaces were fired with run-of-mine coal on grates until April 1911, when oil firing was introduced. Oil firing continued until April 1918, when the initial coal-pulverizing plant was started.' Early Pulverizing Plant Various alterations were made to that plant during its operation, one of the more important being in connection with the system for delivering pulverized coal. In order to minimize coal-dust explosions and fires, the return portion of the main delivery line was eliminated in the year 1928. Thereafter coal-dust explosions and fires were greatly reduced. Pulverized coal was prepared at this plant primarily for the reverberatory furnaces, but for several years it was also delivered to the converting plant, roasters and power-plant boilers by a system of auxiliary fans and delivery lines. During the period March 29 to April 8, 1929, one reverberatory furnace was fired with pulverized coal produced by an Aero, type J, unit coal pulverizer with a rated capacity of 5 tons per hour. This machine actually pulverized its rated capacity but the product was too coarse. After certain regulations, a her product was obtained but the pulverizer capacity decreased and this resulted in insufficient coal for efficient furnace operation. Table I gives a comparison of the average screen analyses of the pulverized-coal products from the impact-type unit pulverizer and the regular coal-plant installation. It was definitely proved that this size and type of unit pulverizer could not furnish sufficient coal of proper fineness to give smelting results comparable to that obtained with the regular coal-pulverizing plant. The coal from this unit pulverizer was so coarse that it did not ignite or burn properly and thus did not produce the proper heat for efficient smelting. During the latter part of 1929 and the early part of 1930, experimental work was conducted with a 7-ft. o-in. by 48-in. Hardinge conical ball-mill coal-grinding unit, which was installed alongside a furnace in the reverberatory building. Results obtained from the test run indicated that this unit would furnish sufficient coal of proper fineness for good smelting.

Jan 1, 1947

By Thomas Chance

ALL gravity methods for the separation of ore from gangue, or of slate and other refuse from coal, are based upon differences in the falling velocities, in some fluid medium such as air or water, of the materials to be separated. As all materials falling in a vacuum have the same velocity, independent of the size, shape, weight or specific gravity of their individual particles, it would be more accurate to describe the operation of these methods as depending upon the. retardation of falling velocities effected by the resistance of a fluid medium, this retardation being greater for small or light particles than for large or heavy particles. This generalization is true also of those appliances utilizing centrifugal force to replace or to supplement the action of gravity. The separation of materials of different specific gravities by means of a fluid having a specific gravity greater than that of the lighter particles and less than that of the heavier particles has not been applied commercially, or on a large scale, to the separation of ores or to the washing of coal, the method being limited to laboratory experimental work or to laboratory determinations for the purpose of checking up the work of jigs, classifiers, and other types of concentrating appliances. A solution of zinc chloride has thus come into general use inn the laboratory to separate coal, bony coal and slate, both to check up the work of coal-washing plants and for the purpose of making tests preliminary to the designing of coal-washing plants. The use of a heavy solution of some chemical in water has often been proposed for making such separations, especially in connection with the washing or preparation of coal. Practically insuperable difficulties, however, have prevented the commercial development of any such process, the difficulties being both physical and financial. The cost of the chemical used to make high-gravity solutions is usually prohibitive, and the freeing of the coal from all traces of the chemical is found to be practically impossible. Such solutions inevitably penetrate the individual lumps and particles of coal, transfusing into the pores and saturating the joint-planes, and very large quantities of wash water

Jan 2, 1918

By Earl R. Johnson

Ore broken at the mine or quarry face generally is loaded by power shovels into large trucks or rail cars and hauled to a primary crushing plant where it is reduced to a more workable size for ease in handling. The primary crushing plant is customarily located as close as possible to the center of gravity of the ore body and the projected limits of the mine pit to minimize the cost of hauling and to increase safety from flying rock as a result of blasting operations. A belt conveyor is used to transport the crushed product to a nearby ore treatment plant or, should this plant be located some distance away, the ore is loaded directly into cars and hauled by rail. Between trips the crusher product is accumulated in bins or stock piles. In all open pit mining and quarrying operations, the power shovel, the transportation equipment, and the primary crushing plant should work as a team, complementing each other. When establishing the design and selecting the equipment for these closely integrated operations, capital and operating costs for each unit operation must be weighed to achieve an optimum balance. Rising labor costs have given impetus to the universal trend toward greater efficiency, higher speed and larger equipment, and higher degrees of automatic control. The result is that power shovels have increased in size, haulage trucks are larger and faster, and only coarse crushers with feed openings adequate to receive run-of-mine lumps of ore with a minimum of secondary blasting are selected for new installations. These coarse crushers also have large through-put capacities, even when adjusted to produce a 6- to 10-in. size of product, thus making it possible to use a single stage of coarse crushing at the average mine. The use of a single crusher results in a compact crushing plant layout consisting of a dumping pocket for receiving loads of run-of-mine ore, a coarse crusher followed by a surge chamber for the crushed product, and a feeder to withdraw the ore at a uniform rate to deposit it on a belt conveyor. A

Jan 1, 1968

By Robert Craig, Earl L. Rau

Introduction Grinding circuits are used to reduce the particle size of ores to the size desired for beneficiation or to grind a concentrate to a size required for final marketing. Grinding and classification can be carried out using either wet or dry circuits. Most sulfide ores are ground in wet circuits using one or more stages of grinding to obtain the necessary mineral liberation to produce a final concentrate which will meet the desired criteria. Iron ores are ground in circuits applicable to the particular ore using either wet or dry grinding. Nonmetallic minerals frequently present different requirements. Barite is likely to be subjected to wet grinding before beneficiating the ore; the concentrate is dried and then dry ground to meet market particle size requirements. The one thing that most mill operators will agree to is that there is no such thing as the "best" configuration of equipment for grinding. The circuit which works well on one ore may be totally unsatisfactory for another ore body. The general trend in the industry is flow sheet simplication with fewer parallel circuits instead of multiple-line circuits using small mills. This change in philosophy has been brought about by the saving of both capital and operating costs that may be possible with larger equipment. Remember that comminution is basically a very inefficient process, and that the costs can range upwards to 50% of the total milling costs. It, therefore, behooves the mill operator to carefully design his grinding and classification circuits. He must ascertain the optimal economic particle size for beneficiation and then make certain he has achieved the best balance between capital and operating costs to achieve the desired mesh of grind. Equipment Grinding circuits consist of one or more pieces of equipment to grind the solids. Generally, these circuits include one or more grinding mills, classification equipment, and the necessary materials handling equipment such as pumps, pipelines, and conveyors. There are many different types of equipment available which are used to grind and classify ores and minerals. Following is a tabulation of most of the equipment used for wet and/or dry grinding.

Jan 1, 1982