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By Edward A. Vitunac

The emerging importance of pneumatic conveying systems for bulk materials is largely due to the economic advantages such systems frequently exhibit when compared to alternate methods. Included in these advantages are relative simplicity, ease of installation, flexibility, ease of maintenance, cleanliness, safety and ease of automation to the degree desired. In general, installed costs favor a pneumatic system when compared to competing mechanical systems if the transporting distances are long or to and from many points. In addition, supplemental use such as cooling, heating, or drying may supply the incremental value required to justify its selection.1 The main disadvantages of a pneumatic system are the greater horsepower required per unit weight of material conveyed, material limits in abrasiveness, and density. In addition, material breakage tends to increase at changes of direction and at any obstruction such as that caused by the imperfect butting of two pipe sections in the conveying line. Classification of the material at the discharge may also cause problems in dusting and segregation. Materials weighing less than 4 lb per cu ft tend to cause feeding and collecting problems although they can be conveyed easily. Material between 4 lb and 20 lb per cu ft can be handled with fewer problems, but flow rate is hard to predict. The 20-60 lb per cu ft range offers best results, whereas materials of over 60 Ib per cu ft tend to drop out of the air stream and settle in the pipeline unless careful pro- visions are made to prevent this.2

Jan 5, 1968

By R. Van A. Norris

The following tests were made, during 1889, for the Susquehanna Coal Company, to determine the relative efficiency of several styles of mine-car wheels in use at their collieries at Nanticoke, Pa. The wheels experimented upon may be divided into two classes: The "old style" (Figs. 1 and 2), which are oiled at every trip; and the "new style" (Figs. 3, 4, and 5), which require oiling about once in two to four months. Fig. 1 shows a section of a plain cast wheel, with patent annular oil-chamber. This is held in position on the axle by a square, split cotter-pin. Fig. 2 is a similar wheel, with a patent cast bushing, which is readily replaced when worn. The lubrication is effected by a simple oil-hole, but the oil is delivered a little inside of the gaugeline of the wheel, where it is most needed. Figs. 3, 4, and 5 are sections of a " new style " patented, self-oiling wheel. In this, the outer end is cast closed, and the wheel is fastened to the axle by a spring cotter-pin passed through one of the plugged holes. Dirt is prevented from entering the open end by a cap, with faced end and packing-ring, fitting over the end of the hub. The lubricant is introduced into the oil-chamber through one of the plugged holes in the hub. When the wheel is in motion, the lubricant is thrown by centrifugal force away from the axle, enters the two ports shown, and is

Jan 1, 1890

By E. H. Dix

The purpose of this paper is to introduce the subject of Stress-Corrosion Cracking at the Joint Symposium of the American Society for Testing Materials and the American Institute of Mining and Metallurgical Engineers. In this Symposium we are concerned with spontaneous cracking which results from the combined effect of high, prolonged stress, and corrosive attack. Stress-corrosion cracking may be considered a specific phase of the more general subject of the effect of high constant stresses in accelerating the rate of corrosion of metal products. The kindred subject of corrosion fatigue in which the life of a metal part under repeated stresses is reduced by corrosive attack is not a part of this Symposium. Likewise "creep," the failure of a metal part by high constantly applied stress, in the absence of a corrosive environment, is not to be included. How- ever, corrosive influences may have more effect on creep failures than is sometimes realized. The penetration by molten metals such as often occurs during tinning or soldering operations, or by mercury, frequently causes cracking when the part is stressed. Strictly speaking this is not stress-corrosion cracking. However, the committee has decided that this phenomenon should be included in the Symposium. The penetration by molten metals such as often occurs during tinning or soldering operations, or by mercury, frequently causes cracking when the part is stressed. Strictly speaking this is not stress-corrosion cracking. However, the committee has decided that this phenomenon should be included in the Symposium.

Jan 1, 1945

By C. O. Babcock

In this Bureau of Mines report, the authors present the results of laboratory tests on the burst proneness of coal. Many researchers have studied the violent breaking of large coal masses in underground mines, called bursts, but the causes remain uncertain. They have often assigned to geology and gas pressure the causative roles. The objective of this work is to show that stress can produce bursts in many coals if constraint is necessary for pillar survival and is suddenly lost. We tested coal samples from 15 mines, in 11 coal seams, in six states in the laboratory, and 13 were made to burst. These bursts were produced in several ways, but segmented steel platens were used in the tests reported. Two parameters analogous to the momentum and kinetic energy were used to rank the burst proneness of the coals tested. Tangential strains over the lower surface of the model coal pillar were measured to reveal a periodic slipping prior to the burst. High-speed motion pictures (350 frames per second) reveal the burst behavior in slow motion. We propose a modified Mohr-Coulomb stress-failure criterion to describe the burst behavior. When the horizontal constraint is suddenly lost with little change in the vertical stress, the Mohr stress circle increases in size dynamically, exceeding the static failure condition. When the inertia of the coal mass is overcome, a burst occurs. We conclude that most coals can be made to burst and that such bursts can be expected in mining at increasing depths.

Jan 1, 1984

By E. J. Magri, D. M. Hawkins

This paper deals with an experimental programme carried out with a gold analyser in the period June to September 1979 at Loraine Gold Mines. The results were found to be reproducible, with no overall or conditional bias when the measurements were compared with those obtained from chip samples. The standard error of estimation of a 3 m reef exposure, which was the sampling interval, can be reduced by a factor of 2,5 if the complete stretch is scanned, rather than the taking of one chip sample in its centre. Complete statistical and computational procedures were developed for the fitting of the normal-Iognormal model to observed analyser data and for the determination of the most likely gold grade for a particular analyser measurement. (This corection procedure is necessary since a significant number of negative analyser measurements can be observed.) Panel averages of uncorrected scans showed a small conditional bias relative to those of corrected scans. However, uncorrected panel averages can be used for on-the-spot decisions regarding whole panels. For standard calculations of ore reserves, use should be made of corrected scans. Under reasonable assumptions, the use of the detector in the selective mining of low-grade narrow reefs such as the Basal Reef at Loraine Gold Mines, when compared with the conventional chip-sampling method, can result in a saving of as high as R40 million in present-money terms over the life of a project. The difference could be even larger in a highly variable reef like the B Reef at Loraine Gold Mines.

Jan 1, 1987

By B. H. Bergstrom, C. L. Stevenson

In any process wherein materials must be pelletized, a crucial period exists during the interval between the manufacture of the green pellets and their subsequent heat treatment. The pellets must possess sufficient strength and plasticity to withstand conveying and sizing. Also, they must be neither excessively brittle nor excessively plastic when placed in a bed on a traveling grate for heat treatment. An acceptable pellet, in the event sufficient forces are applied to cause its fracture, will merely split into two or three large fragments which would not drastically alter the permeability of the pellet bed. However, when brittle pellets are broken, they shatter so that the resultant fine particles either decrease the perimeability of the bed or become entrained in the gas stream and thereby cause dust problems. On the other hand, excessively plastic pellets may not break at all but may merely flatten. This would seriously hamper bed permeability. In the past, pellet evaluation has usually been left to the creative and artistic talents of the balling operators. A multitude of techniques have evolved, of which the most common is the simple compression test. For this test a hand-operated device loads single pellets to fracture, but reliability is strictly operator- dependent. Probably the next most common test is the drop test, which is conducted according to several different procedures. This is an important quantitative test for estimating the amount of handling a pellet will withstand. There are many other tests, such as pinching a pellet between the thumb and index finger, but none are capable of producing reproducible results.

Jan 4, 1962

By Michael Gauna, William J. Gray, Joseph C. Zelanko

Mechanized mining in the underground coal industry has continued to evolve since the introduction of the remote control mining machine. Remote control continuous mining machines without an onboard operator’s compartment are now the norm in the industry. Extended cuts in excess of 30 ft (9.1 m) are commonplace. Unfortunately, machine operator positioning has become an often unrecognized safety concern, particularly when remote control continuous mining machines excavate a turn (turn a crosscut). From January 2001 through July 2004, remote control continuous mining machine operators or helpers have been involved in ten roof fall fatalities and eight machinery crushing fatalities. The machinery crushing incidents occurred when machines were being repositioned or moved to another place. Of the ten roof fall fatalities, three occurred while a crosscut was being turned and a fourth fatality occurred while mining was being conducted adjacent to the crosscut. The operating time associated with turning crosscuts is a relatively small part of the mining cycle. In recent years, however, a disproportionate number of fatal incidents appear to have been associated with this activity. Procedures for reducing the incidence of operator fatalities while turning crosscuts are discussed. These techniques include: minimizing the number of turn cuts, limiting turn cut depth, establishing no work zones and using visual warning devices to designate them, installing more roof/rib support in the vicinity of the turn cut, using notch cuts prior to initiating a full turn cut, and positioning the remote control miner operator in nontraditional locations.

Jan 1, 2005

By G. Labonté, J. Truskoski, A. Kerr, A. Bouchard, J. Barrett

"Improving mill grade recovery relationships is always good business. Inco’s Clarabelle mill has just undergone a $16 M process upgrade that was designed to improve nickel recovery by 2%. The “Mill Redesign Project” was completed on time, under budget and delivered the promised improvement in recoveries.This paper describes the methodology of the Mill Redesign Project team, details of the process improvements and the critical success factors that helped the team deliver on its promises.With a payback of under one year, the Mill Redesign Project will play a key role in ensuring a competitive edge as Inco embarks on its second century of operation. IntroductionIt is not uncommon in milling operations to encounter a crisis. That is the point when the process does not behave as expected and fails to respond to the increasingly desperate efforts of the metallurgists and operators. Flowsheet and process changes are attempted and abandoned. With luck, one or more of the changes achieves some mitigation of the original problem or more usually, the original cause of the problem disappears. Regardless, the metallurgist can sit back and bask in the apparent success of his or her endeavours.Less common is when a problem is carefully diagnosed, a team put together to explore all avenues and recommend a path of action that is implemented on time, on budget and immediately delivers on the promises which are sustained over time. This is one such story. It is the story of the Mill Redesign Project at Inco’s Clarabelle mill in Copper Cliff, Ontario."

Jan 1, 2003

During the course of an investigation into the fundamental chemistry of the cyanide process, it became evident that the usual method of determining protective alkalinity was not completely satisfactory. T.he routine method for the determination of protective alkali by first removing free cyanide by the addition of silver nitrate, followed by titration of alkali with dilute acid using. phenolphthalein as indicator, can be shown to give correct results only when the alkali is a strong base. For other sUbstances, the alkali so determined is not the protective alkali. In view of the complications associated with the presence of zinc in cyanide solutions the discussion will be restricted in the first place to solutions free from zinc. Until the chemistry of simple cyanide solutions is placed on a quantitative basis it will be difficult to elucidate the behaviour of complex mill solutions.By the use of physico-chemical theory, it is possible to treat certain aspects of 'the chemistry of cyanide solutions in a manner which not only illustrates the important variables involved, but which also shows the need for care in interpretIng results obtained by conventional methods.In the following, comparatively simple systems are discussed; the principles established should be of use in interpreting the behaviour of more complex solutions. The methods described are not intended for routine work, but may be regarded as supplementary to the usual analysis carried out for the control of plant solutions, or as alternatives to be used when the latter do not appear to be satisfactory.

Jan 1, 1948

By I. Iwasaki

In the flotation of iron ores and nonmetallic ores desliming is the key to a successful operation; the technology of flotation of well-deslimed ores has become fairly well established. When finely disseminated ores are ground to liberation, however, conventional desliming of the fully dispersed pulp results in an excessive loss of valuable constituents. Selective flocculation of iron oxides followed by removal of dispersed siliceous slimes is a new development and is one of the most promising approaches to the treatment of finely disseminated, oxidized iron ores, available in vast quantities both here and abroad (1,2,3). To apply selective flocculation to the variety of refractory iron ores or to cope with the fluctuations in an individual ore and the make-up water, the factors governing this technique must be clearly formulated. For the removal of siliceous and clayey slimes from oxidized iron ores by selective flocculation, the optimum conditions are extremely sensitive to the mineralogical characteristics of the ore, the type and the amount of soluble salts in pulp solutions, and the mesh-of-grind. Certain starches appear to function better than others (4, 5). Selection of the proper reagents and their judicious use is important not only for their efficient utilization but also for minimizing the adverse effects they might exert on the flocculation and flotation steps, and the pollution the effluents might cause when discharged, either intentionally or accidentally, into lakes and streams. In the present article some of the major factors that influence the selective flocculation of iron ores are summarized.

Jan 1, 1979

By Walter Weeks

CONSIDERABLE difference of opinion seems to exist as to whether the rate of air flow when a fan is placed on a given duct should be determined by the use of static pressure or total pressure characteristics. A little study will show that both methods are correct. Assume that a fan is connected to a duct by an expansion piece as shown in Fig. 1, and that steady flow is established. Considering the atmospheric pressure as zero pressure, let the static head at the outlet of the fan be h and the velocity at this point be v1. The total head at the outlet is then h + v1/2g? The total head at this point must be equal to the total head at the end of the duct plus the losses that have occurred between the two points. Let f be the friction loss in the straight duct, s the shock loss in the dif- fuser, and V2 the velocity at the end of the duct. Then h+ v12/2g=v22/2g + f + s FIG. 1.-FAN ON DUCT. A curve showing the value of the left-hand side of the equation for different rates of flow is the total pressure characteristic of the fan, while a curve showing the value of the right-hand side is the total pressure characteristic of the duct. If these two curves are plotted on the same chart, the intersection indicates the rate of flow when steady flow is established.

Jan 1, 1930

By Frederic P. Dewey

By the old method of determining platinum in ores and bullion, the silver-alloy first obtained in the regular course of assay is parted in strong sulphuric acid and the residual metal weighed. This is re-alloyed with silver by a second cupellation and parted in nitric acid, the residual metal being again weighed. Any difference shown between the two weighings is assumed to be, and is called, platinum. Sometimes it is SO, and if any considerable amount of platinum be present, there will be a decided difference between the two weighings; but a slight difference is no real evidence whatever of the presence of platinum. On the other hand, the second weight may equal or possibly exceed the first, even when traces of platinum are present. Again, other members of the platinum group may go into solution in nitric acid more or less. If present, these would be called platinum and escape detection. The method does not provide any direct tests whatever as to the presence or absence of platinum. It is often indecisive, and sometimes gives erroneous results. It is, therefore, quite unsatisfactory. Being called upon many times to determine platinum in a wide variety of materials, particularly when present in very small amounts, I have realized the disadvantages and defects of this old method. In an article on the solubility of gold in nitric acid,' I have briefly outlined a method of gathering a little gold out of a solution containing much silver, which furnishes the basis of

Jan 1, 1913

By Carl S. Westerberg

1,. C. McCABE*-—An increased derliand for coal in the west is to be expected because of the growth in population and industry during the past ten years. The author calls attention to the increased mechanical cleaning of Utah coal between 1938, when no cleaning was being done, and 194.7, when more than 24 pct of the production was cleaned. This is essentially the Period of most rapid growth of the Pacific Coast. area altliough the growth and, no doubt, the general trends in coal production and cleaning continued at a less accelerated rate during 1948. The Pacific southwest increased 37 pct in population between 1940 and 191.7 while the United States showed only a 7 pct increase in the same period. it has been estimated that there will be an additional 15 pct increase in population between 1947 and 1950. The conclusion that more coal and more mechanicak cleaning capacity will be required appears to be well founded. Mr. Westerberg discusses the cco- nomic advantages of coal cleaning reflected in freight savings, in lower cost per million Btu, and lowered ash and sulphur content. In view of the limited occurrence of coking coals in the west it would be interesting to know whether significant beneficiation in coking strength can be expected from mechanical cleaning of Utah coals. This has been demonstrated for some eastern and midwestern coals. One can readily agree to the desirability of recovering the fine coal that has heretofore been lost in washery slurry. The very cheapness of coal has Iridered

Jan 1, 1950

By Frank Hall

THE needs of the World War showed the necessity of a metal stronger than cast iron which would supplement the supply of steel. So patriotic metallurgists were spurred to new efforts to improve the status of that half-breed of the metal world that had been, more or less erroneously, christened semisteel. As a result, it was developed that for certain purposes semisteel was superior to steel in the manufacture of shells. Steel, because of its greater strength and toughness, is able to carry a greater charge of explosive, weight for weight; consequently, a steel shell can be expected to cause greater destruction when used against fortifications or other inanimate objects, while semisteel, because of its comparative brittleness and its resulting greater fragmentation, is capable of inflicting more serious loss of life when used against opposing forces of men. Therefore, each has its proper place in the economy of war. For the present purpose, steel may be defined as a comparatively pure iron whose physical nature is modified by small amounts of carbon, silicon, sulfur, phosphorus, manganese, and possibly other rarer elements; while cast iron generally is limited to approximately 93 per cent. of iron, the remainder consisting of larger percentages of carbon, silicon, sulfur, phosphorus, and manganese. Semisteel may be defined as cast iron in which the carbon and silicon have been reduced to as low a point as is consistent with maintaining the nature of gray iron, and in which the remaining elements are manipulated so as to give the greatest strength.

Jan 1, 1920

"Silver is traditionally recovered in base metal smelters (lead and copper), or as a by-product of other precious metals (gold and/or PGM's). This paper presents the results of non-conventional techniques to recover silver from complex materials. The PLATSOL® process has been developed to recover, in one step and without the use of cyanide, base metals (copper, cobalt, nickel) and precious metals (gold, PGM's) from sulphide concentrates too low in grade to enter the mainstream extraction processes. Silver is only partially recovered in solution with gold and the PGM's during the PLATSOL® process. However, the silver minerals are transformed into silver chloride, which can then be recovered from the PLATSOL® residue using conventional techniques. Some South American silver concentrates contain levels of impurity (mostly arsenic) so elevated that the penalties incurred significantly affect the process economics. The present results have shown that a low temperature calcination process transforms the concentrate into a product well suited for traditional recovery treatments. Metallurgical details will be provided, as well as the results of mineralogical studies that helped clarify the process mechanisms.IntroductionSilver occurrences in nature are very diversified, and, therefore, primary silver is produced as a by-product of many base metal and precious metal operations [1], as well as a co-product of most gold ores. However, difficulties can arise when high temperature processes are used for refractory gold ores or copper concentrates, or when the silver concentrate contains impurity elements such as arsenic that trigger high penalties."

Jan 1, 2012

By Edward C. Morse

The metallurgical history of Republic has been completely reviewed in a paper presented at a previous meeting of the Spokane Local Section by Professor Thomson;' therefore, the present paper will be confined to matters directly pertaining to the San Poil mill: When I came to Republic last fall to look over the situation there was a plant in operation successfully treating the tailings from one of the earlier mills in the camp. I refer to the mill of the Rathfon Reduction Co. This mill was operating in accordance with modern cyaniding practice, and I was given to understand that the work was very satisfactory and profitable, else it would not have been continued as long as it was. At that time I obtained much metallurgical information of value from Harry W. Newton, Superintendent of the mill of the North Washington Power & Reduction Co. I took a number of samples from the San Poil mine, with the view of determining if Mr. Newton's experience with the ores from the other mines applied to the San Poil ores. I made a large number of tests under a variety of conditions, and found that it was possible to extract as high as 98 per cent, of the values from San Poil ore by the laboratory-tests when the ore was pulverized to 200-mesh and treated with a solution of a strength of 5 Ib. of KCN to the ton. A fairly strong solution was required because of the proportion of silver in the ore, which makes it, from a metallurgical point of view, practically

Jan 1, 1913

By R. P. McLaughlin

IN most branches of the mining industry it is a well-recognized fact that care must be taken to protect the mineral deposit from undue physical injury. It is comparatively easy to grasp this idea when the mineral is a solid and the lives of workmen depend directly upon the care with which it is removed from its natural position, but when the product is a liquid. drawn up from pools several thousand feet beneath the surface of the ground through openings only a few inches in diameter, it requires some imagination to picture underground conditions and the changes which must often occur. The development of the petroleum deposits of California has been attended by numerous accidents, the results of which are readily noticed at the top of the wells and in the profit and loss accounts of the operators. Determination of the cause of these accidents has been the subject of considerable study, which naturally has fallen upon men familiar with technical methods. The greatest damage to the oil deposits of California has resulted from water finding its way into the oil-bearing sands, and it is the purpose of this paper to set forth briefly this phase of the oil industry. Much of the material here presented has previously appeared inn publications issued by the California State Mining Bureau, which, under the direction of State. Mineralogist Fletcher McN. Hamilton, has investigated the subject and taken steps toward improvement of conditions. The writer, having been in charge of this branch of the Bureau work, has gained considerable knowledge of existing conditions.

Jan 12, 1915

By George Breyer

DURING the past 25 years the steelmaker has experienced some difficulty in producing steel to meet the standards established by the metallurgist. In contrast to the past, when a chemical specification of broad limits was the only requirement, he now has to employ such tests as microscopic, macroscopic, tensile, impact, Magnaflux and even X-ray and supersonic. The development of these tests has more than set the pace for a manufacturing process of which the exactness still hinges to an important degree on the ability of the furnace operator. In our efforts to produce steel, and especially alloy steel, to meet the exactness of modern engineering specification, many factors must be taken into account. It is not sufficient to make a good heat of steel in the furnace and then be satisfied that the job is done, since there are many pitfalls between the furnace and the finished product. The literature abounds with information on melting practices, deoxidation methods and slag control, but the lack of positive information about what happens when the steel is teemed into molds is quite evident. Such questions as what is the proper mold size, shape and thickness; which is the best mold coating; what is the best rate of pour for any given steel, and what is the effect of cooling rates on quality, are still answered by opinions. It is acknowledged that a poor heat of steel cannot be improved in the pouring pit. On the other hand, a good heat can be ruined by improper handling after it leaves the furnace.

Jan 1, 1947

By F. Weinberg

WHEN impure Zn (< 99.99 pct)&apos;&apos;Z or Zn-Cd alloys3 are progressively solidified, a cell or "corrugation" substructure4 is produced in the solid, with a high impurity or solute concentration along the cell walls. When these materials are polished and suitably etched, etch pits are often observed along the cell walls. For the Zn-Cd alloys these etch pits have been associated with decorated dislocations, present in the corrugation boundaries to accommodate the lattice strain. In the course of an investigation of Zn-2 pct Au alloy, molten metal of this alloy was poured into cold water and the resultant solid pieces were sectioned, polished and etched with a Cr0 ethant. An extremely regular cell pattern was observed on the etched surface, similar in general to the corrugation structure previously reported for impure zinc and Zn-Cd alloys. At higher magnification, regularly spaced pits were observed along the cell boundaries. An example of the regular cell pattern at the center of a specimen is shown in the center and lower portions of Fig. 1; the top of the figure shows the pattern near the specimen surface. Typical etch pits in the cell walls are shown in Fig. 2. It was surprising that a cell pattern as regular as that shown in the center of Fig. 1 was produced at the very rapid solidification rates used (estimated as > 1 cm per sec). In addition, the distribution coefficient for the Zn-Au system is greater than 1. Accordingly, the center of the cells should be rich in solute and should etch

Jan 1, 1963

By J. W. Koger, R. E. Hurnrnel

QUENCHED, bcc p brass, P1, transforms to a mar-tensitic phase, when it is cooled below room temperature.&apos; This transformation can be followed using resistance measurements since the resistivity of the martensitic phase is considerably larger than that of the parent phase, Fig. 1.&apos; phillips3 first reported that, when Cu-Zn alloys containing between 37.0 and 39.0 wt pct Zn were quenched from the 0 region to room temperature, variable amounts of a phase could be observed depending on the mode of quenching. If the quench occurs very rapidly, the a phase forms by a "massive transformation". The resultant phase has the same composition as the high-temperature P phase from which it was formed. If the quench is less severe, the alloy is retained largely in the p form; however, some a is formed by precipitation. In this case, a contains more copper than the high-temperature 0 phase from which it has formed. The a phase most probably does not undergo a transformation in the temperature range where p transforms to low-temperature martensite. This can be deduced from the Eesistivity-temperature relation which is linear in this temperature range, Fig. 2. The stable a phase which is present along with R. E. HUMMEL is Assistant Professor, Department of Metallurgical and Materials Engineering, University of Florida, Gainesville, Fla. J. W. KOGER, Junior Member AIME, formerly with University of Florida, is now with Oak Ridge National Laboratory, Oak Ridge, Tenn. Manuscript submitted December 13, 1967. IMD.

Jan 1, 1969