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SAMUEL L. HOYT,* Minneapolis, Minn. -I was privileged to see the apparatus used by Mr. Scott, which is quite unique. It is, as the author says, a modification of the apparatus designed by Dr. Rosenhain, but it is evidently quite an; improvement. The author is to be congratulated on the fact that lie has given us, with his apparatus, a quantitative thermal analysis of these critical points. I notice the author refers to Ac3, Ac2, and Ac1. His designation of the Ac2 point is all right, but naturally in a steel with as much carbon as this, which would mean a hypereutectic steel, the other point might better be considered as an Ac, point with possibly another point above the Ac, point. Another important point brought out is the fact that, in Fig. 3, the lines representing the Ar1, transformation and the Ac,1_3 transformation do not intersect at the zero rate curve,

Jan 5, 1919

By David S. Butts

There are many solution mining operations that use solar ponds as a mineral recovery step. Other locations in the world are now under investigation to recover minerals by solution mining but require the cheap energy of solar ponds to make the recovery viable. This paper shows a step-by-step material balance system that can be used in both simple and complex solar ponds. Use of this system will help the engineer determine if solar ponding efficiency can be improved or if solar ponding will work at all with a given set of conditions. Even the most complicated solar pond can be reduced to six flow streams. These are (1) feed, (2) exit, (3) leakage, (4) entrainment, (5) salts, and (6) evaporation. The equations developed in this paper will allow the solar pond engineer to easily evaluate the effect of each of the flow streams on the mineral production of a pond or pond complex.

Jan 1, 1985

By E. H. Rennhack

When cast hypoeutectic Zn-Ti alloys are rolled, the TiZn15 compound particles arising from eutectic decomposition form a network of fibers promoting improved creep resistance.' The effect is magnified with increasing titanium content and extends to hy-pereutectic concentrations. Strip produced from the latter-type alloys, however, also contains large, primary crystals of the compound that tend to initiate cracking during subsequent fabrication operations. In a study of the influence of various casting modifications on the size and distribution of these crystals, the phase relationships existing between the eutectic and the TiZnIs intermetallic compound in the Zn-Ti system were of major interest. Although several in- vestigators1 4 have explored the equilibria within this compositional range, their results show considerable lack of agreement. Consequently, with the exception of the solvus boundary, the constitution of this system containing up to approximately 1.0 wt pct Ti was . The findings are reported in the present note.

Jan 1, 1967

By R. D. Groves, G. M. Potter, T. H. Jeffers

Experiments on ammonium carbonate leaching of native copper ores crushed to 1-inch size showed that in 30 days 55 percent of the copper was extracted from 0.7 percent copper conglomerate-type ore, and 85 percent was extracted from 2.1 percent copper amygdaloid-type ore. Cupric ions were not necessary to initiate leaching, and dilute solution containing only 2.2 grams per liter NH3 and 1.9 grams CO, was a suitable solvent. Copper was recovered from the leach liquor by solvent extraction and electrolysis of the strip solution. Cyclic testing of the leach-solvent extraction-electrolytic procedure is in progress on a 6-ton charge of minus 12-inch conglomerate-type ore assaying 2.2 percent copper. Oxygen is metered to the closed leach vessel as required by the leaching reaction. Initial copper dissolution was much slower than from minus 1-inch ore, but the leaching rate then markedly improved.

Jan 1, 1974

By H. M. St. John

LIKE every present-day manufacturer, the brass foundryman is faced with the necessity of reducing the cost of his finished product without impairing its appearance or quality. He must use every economy that the progress of art and science puts at his disposal and should also be alert to profit by any peculiarity in his own situation or the nature of his product that may give him an exceptional advantage. Much can be accomplished by the adoption of labor-saving equipment and improved methods of melting, molding and handling. Control of pouring temperature, study of defective castings and their causes, laboratory control of molding sand and core mixtures, the use of less expensive alloys, all contribute to the desired end. Assuming that the composition of the alloy is already as inexpensive as the character of the casting will permit, still further savings can be made by the intelligent purchase and utilization of the metals needed to produce the desired analysis.

Jan 1, 1929

By Charles J. Lipton

Third World countries have lately taken a variety of actions to improve their revenues from the development of their mineral resources. Increasingly, their governments seek to negotiate production agreements on the basis of feasibility studies and discounted cash flow projections. Developing countries are now more selective in giving incentives to encourage investment in the mining sector. They recognize the value of their contributions to mining projects by way of guarantees and the provision of infrastructure. Third World governments now seek to participate in the basic decision making which determines profitability, such as loan-equity ratios, plant capacity, and processing and sales arrangements. They are alert to the benefits of large-scale development and appreciate their risks. They seek to increase their benefits from foreign exchange earnings and the multiplier effect of mining projects. New forms of arrangements are being used to insure that the mining sector is developed in harmony with the national objectives of the Third World.

Jan 1, 1977

By Atmesh K. Sinha

In spite of the artificial supports which are provided to reinforce the mine roof and prevent failures, roof falls continue to occur very frequently in the mines due to the very unpredictable geological conditions and the dynamic nature of the mining operations. In fact, roof fall is still one of the largest contributor to coal mine fatalities. The design of a roof support plan is often based on arbitrary criterions due to the unpredictable behaviour of the rocks under the mining conditions. The failure of a mine roof which ultimately results in a roof fall and contribute to mine hazards, is caused following a gradual degradation in its physical conditions. A mine roof monitoring system capable of monitoring the rate of deterioration of a mine roof on a continuous basis has been developed and tested in an operating coal mine. The monitor can help to improve and supplement the roof support plans and

Jan 1, 1983

By R. J. Lipp, I. Iwasaki, R. H. Heerema

The presence of calcium ion in iron ore pulps that are upgraded by selective desliming can result in indiscriminate flocculation of both iron oxide and siliceous gangue slimes. In order to overcome this adverse effect, deflocculation by three complexing agents, namely ethylenediaminetetzaacetate (EDTA), sodium tripolyphosphate (STPP), and sodium hexametaphosphate (SHMP), was investigated. The precipitates and complexes of these agents with calcium ion were characterized by potentiometric and conductometric titrations, and the surface properties of quartz and goethite were studied in the presence of calcium ion and of the complexing agents by means of streaming potential measurements and flotation tests. The results were then correlated with selective flocculation tests on an artificial mixture of quartz and goethite. EDTA markedly improved the selectivity of flocculation when added in near stoichiometric amounts, whereas STPP was less effective and SHMP was totally ineffective due to strong, indiscriminate dispersion. Remanent calcium polyphosphates on the goethite surface interfered with the adsorption of starch flocculant.

Jan 1, 1983

By Ralph K. Foster

During five underground mine fires which occurred in Arizona during 1980 and 1981, sealing the fire area became necessary. To minimize leakage into the fire area, ventilation control measures were instituted to balance pressure across the bulkheads. Problems en- countered in sealing the fire areas and measures taken to improve these conditions are discussed. The routing of the ventilation and ventilation control to en- sure the workers' safety were also important considerations in reopening the mines. The use of continuous CO monitors is discussed. One important consideration was the condition of the fire, and chromatographic analysis was used to establish this. Graphs comparing the Trickett ratio, carbon monoxide, carbon dioxide, and oxygen concentrations are given. The Trickett ratio was useful but needed to be augmented by the comparison of CO, C02, and 02. Problems with getting good samples from sealed areas and recommended procedures that were developed during these fires are discussed.

Jan 1, 1982

By Schrade F. Radtke

The future of lead and zinc, as with any material, will relate directly to their capability to remain competitive; that is, to demonstrate cost-performance ratios that are superior to those of competing materials. These cost-performance ratios are not static; therefore, it is necessary to develop improvements in products or processes to maintain present markets or to penetrate other markets. Perhaps the surest way to achieve these goals, if they can be achieved at all, is through research. The world lead and zinc producing industry established ILZRO as its cooperative research function to carry on both fundamental and applied research and development efforts aimed at the stated objectives. Current research efforts in the fields of die casting, galvanizing, finishing, chemicals, architectural applications, ceramics, and batteries are reviewed and potential impact assessed, some projections are given of possible new areas of research. Environmental research and its impact on future uses of lead and zinc are also discussed.

Jan 1, 1977

By J. T., Norton

As cold working is an important feature in a great many of the fabricating processes now applied, this paper presents some ideas on the nature and results of the plastic deformation produced in this operation. The art of manufacturing metal for practical uses is very old and has undergone very great development. The science of metals has- also developed very rapidly recently and the various processes to which metals are submitted are much better understood now than they were even a short time ago. All the knowledge that can be obtained on this subject is useful because it promotes efficiency in converting metal into finished articles.

Jan 1, 1927

By J. A. Woolf, E. S. Leaver

THE purpose of this paper is to describe, in a general way, gold-dredging operations in California, with particular reference to unusual features, including types of deposits and recent attempts to improve the recovery of the gold. Dredging Areas The gold-bearing formations that traversed the western slope of the Sierra Nevadas for a north and south distance of some 300 miles furnished the immediate source of the gold found in most of the placer deposits of California. Erosion through a long period carried the gold, together with various forms of partly disintegrated material, to lower elevations and formed placer deposits. Through the classifying action of water in motion, the coarser gold and heavier material of various kinds were - deposited relatively near the source; consequently, in the higher mountain country, old river channels were worked feverishly during the early California gold-rush days because of their high gold content. With the working out of these known high-grade channels, and from the knowledge thus obtained of prehistoric stream beds, drift mining was started and flourished until about 1890. Even today many drift mines are operating with the objective of opening other old Tertiary river channels that have been covered by volcanic flows. Adjacent to these areas, which contained relatively high gold values in the older river channels, smaller particles of gold, gravel, and debris were deposited along the sides of the former stream beds and on the adjoining flat areas, thus forming the large placer deposits, which were worked principally by hydraulic mining. Following the course of the ancient rivers and of the present drainage system to the lower edge of the foothill country, extensive areas of alluvial

Jan 1, 1937

By R. H. Heyer, J. L. Bray, M. E. Carruthers

It is well known that iron markedly improves the physical properties and casting characteristics of aluminum bronzes. The use of 1 to 4 per cent iron as the principal modifying addition has become common practice in many foundries melting aluminum bronzes. Although the beneficial effects of iron are unquestioned, there is some uncertainty regarding the structural changes caused by it in the basic copper-aluminum system. It is agreed that a new constituent appears in abundance when the iron content reaches 2 to 4 per cent. This constituent, which frequently occurs in shapes resembling clover leaves, is sometimes assumed to be an aluminum-iron intermetallic compound. If this were correct we might expect a change in the structural relationships of the matrix in the direction of decreased aluminum content. On the other hand, it has been reported that iron has a negligible effect in altering the fundamental relationships of copper-aluminum alloys1 Others2'3 have reported an additive coefficient. Apparently it will be necessary to know the equilibrium relationships between the phases of the copper-aluminum-iron alloy system to establish any such theory as fact. When this has been done it may very well be that a further revision in the structural relationships may be necessary to describe the changes to be expected in commercial cast alloys. It was with this latter problem before them that the authors attempted to determine the change in the copper-aluminum relations with respect to iron. Objects of the Investigation In certain investigations carried out by the authors for a plant producing a large tonnage of cast aluminum bronzes the structures

Jan 1, 1936

By Bradley Stoughton

[Secretary's Note.—TO avoid repetition of foot-notes, references to authorities are made in this paper by means of figures, referring to a numbered list in the appendix.—J. S. 1 Introduction. This paper gives the results: first,, of a research into the somewhat extensive literature of titanium; and second, of a series of original tests upon the effect of titanium on iron castr ings. New investigations have also been made upon the effect of titanium on steel, but I hope to treat this subject in an independent paper at some later date, and, therefore, will not discuss the experiments in detail here. The combined results of this study, which extended over a period of more than two years, can be briefly summarized as follows : 1. Steel or cast-iron, in which the titanium is properly proportioned, and which has been properly treated, is improved in strength, toughness, and durability against wear, such 'as, for example, the wear of railroad-rails, of steel and chilled-iron rolls, car-wheels, etc. 2. These improvemerits seem to be caused, not so much by the direct effect of titanium on the metal, as by its cleansing influence in removing harmful impurities, such as oxygen and oxides, nitrogen, occluded slags, and perhaps also sulphur. It appears also to reduce segregation, which would contribute to the same end. 3. In order that its effects may be fully realized, the treatment of steel or iron with titanium must be correctly performed. There are a few simple, but essential, details to be observed; if they are neglected, the best results cannot be expected. To illustrate by an example: A series of tests on cast-iron

Jan 1, 1913

By F. W. Bradley

MY first Nevada City mining reminiscence is one of seeing Capt. Thomas Mein, over 52 years ago, in the old Wyoming mill on Deer Creek about a mile below the town of Nevada City. Captain Mein was then superintendent of the Wyoming mine, where the old fashioned Cornish pump was used, as well as hurdy-gurdy water wheels for power. This mill was one of the typical, up-to-date mills of that time and consisted of stamps, fed by Chinese hand feeders, who also cobbed the ore down to a small enough size to be fed into the mortars. Stamps at that time were of light weight and crushed about one ton to one and a half tons to the stamp, the pulp going over plates, then into sluices with self-raising gates. When a sluice became full the pulp was shut off and directed into the parallel sluice, also with a self-raising gate. The concentrate thus collected in the sluice was shoveled out and carried to Cornish buddles and there cleaned up, preparatory to being sent to a local custom chlorination works.

Jan 1, 1929

Far reaching changes in the executive machinery of the Federal Government are proposed in bills recently introduced in each House of Congress. The Department of the Interior will become the Department of Public Works, if the legislation proposed is enacted; the main idea is to assemble all engineering activities of the Government in one department. Such bureaus of the Interior Department as are non-engineering in character are to be placed under the jurisdiction of appropriate departments, while engineering bureaus from other departments are to be included in the Department of Public Works. The bill proposes that the Patent Office is to be removed from the Interior Department and placed under the Department of Commerce. The Bureau of Pensions is assigned to the Department of the Treasury. The Bureau of Education goes to the Labor Department. The Bureau of Indian Affairs is transferred to the Department of Labor, with the proviso that the engineering and construction work and the land and mineral surveys now performed under the direction of the Bureau of Indian Affairs are to he prosecuted under the Department of Public Works. St. Elizabeth's Hospital and the Freedman's Hospital in Washington are assigned to the Treasury Department. Columbia Institution for the Deaf and the Howard University go to the Bureau of Education, under the provisions of the bill. On the other hand, the Department of Public Works is to absorb the Supervising Architect's Office of the Treasury Department; the Construction Division, River and Harbor Improvements, Mississippi River Commission, and California Debris Commission of the War Department; the Bureau of Standards and the Coast and Geodetic Survey of the Department of Commerce; the Bureau of Public Roads and the Forest Service of the Department of Agriculture.

Jan 8, 1919

Dr. Wadsworth's discussion of leaching is straightforward and certainly points out some of the critical areas in regards to the fundamental aspects of leaching. I will address myself to the more practical aspects of leaching. As a couple of general comments, very fine particles are often dealt with only when necessary. In many processing applications the sands and slimes are separated with the sand portion being treated by common metallurgical techniques and the slime portion being treated essentially by any technology that will recover some of the values. Ore treatment techniques such as leach/precipitate/float (LPF) have been used in the copper industry to take advantage of leachable copper preferentially reporting to the fine fraction. The second advantage, of course, is the improved metallurgy associated with the treatment of the sand fraction. Cases can be made for sand/slime separations in the aluminum and uranium industry where most of the value reports to the slime fraction and the sand fraction is rejected In the agitated leach systems, fine particles are often the most readily attacked and leached. In dump, vat and in-situ leaching, fine particles cause considerable problems. The fines will tend to restrict the solution flow from portions of the leach feed. This either causes a significantly reduced solution flow or, more probably, the solution will channel, by-passing much of the ore. In either case the result is a decreased metal recovery from ore. The fine particles of principal concern are clays of a flat plate-like shape which can very effectively compact, swell and cause a decreased solution flow. Discrete silica grains or sulfide grains due to their shape, even though they may be very fine, will not cause nearly the problems clays and secondary precipitates can cause.

Jan 1, 1979

ABIDE from the John Fritz Medal, in which the Institute participates through its representation on the John Fritz Medal Board, the Institute itself has three major awards to make annually and one special prize for excellence in technical papers, as follows. The Robert W. Hunt Medal and Prize, The J. E. Johnson, Jr., Award, the James Douglas Medal, and The Lewisohn Platinum Prize to senior members. ROBERT W. HUNT MEDAL AND PRIZE The partners of Robert W. Hunt established a fund which was presented to the Institute at a fitting' ceremony on May 27, 1920, to establish an annual medal and a sum of money to be awarded under the following rules ? 1 The award shall consist of two prizes, first of a gold medal, second of a sum of money, a certificate to accompany each prize. The money prize shall not be awarded to a member over 40 years of age, but under unusual circumstances, both prizes may be allotted to one person provided that he is not over 40 years of age In general it will be understood that the Committee shall award the money prize to the younger men, rather than the medal. 2 The awards shall be made not oftener than once a year to that person or persons contributing to the Institute the best original paper or papers on iron and steel The scope of the term "iron and steel" shall be determined by the sub-committee considering the awards In general, papers dealing with the practical side of the subject have preference over those dealing with the theoretical side in recognition of the fact that Captain Hunt's main contributions to the industry have been in the improvement of production and quality of material

Jan 1, 1923

The problems associated with the processing of the Tilden ore are very much representative of the problems encountered in plants processing fine grained magnetic and nonmagnetic iron ores. I would like to comment on some of the problems mentioned in Dr. Nummela'spaper and add to his list of research opportunities in the processing of iron ores. Grinding, the most important step in the processing of fine grained iron ores, is synonymous with liberation. One grinds to separate discrete grains of minerals from the gangue. By convention- al grinding in tumbling mills, mostly random size reduction is achieved with relatively little preferential liberation of minerals. Not only are discrete particles broken that should not be broken, but damage is done to the mineral surfaces. The combination of over- grinding and surface damage shows up in lower recovery figures and higher grinding costs. What is obviously needed is a better comminution process that is more discriminating and that would permit liberating mineral particles at the coarsest possible size with a minimum production of fines. Laboratory attempts at such preferential grinding have been quite successful, but technological difficulties have unfortunately prevented its use. Impact grinding is a good example of a new comminution process that has not been accepted because of equipment problems. Either these problems have to be solved or new comminution systems have to be developed to reduce grinding costs and improve liberation. In his paper Dr. Nummela mentions the change in the primary mill throughput that occurs during the winter months. Seasonal changes in the operation of the grinding circuit and other unit operations have been observed in many plants, and many explanations for this phenomenon have been advanced. The fact is that we do not fully

Jan 1, 1979

Discussion of the paper of N. V. Hansell, presented at the Cleveland Meeting, October, 1912, and published in Bulletin No. 72, December, 1912, pp. 1497 to 1,517. C. Q. PAYNE, New York (communication to the Secretary*) :-Mr. Hansell has presented in his paper a very interesting and valuable summary of the various methods of enriching iron-ores which have been developed during recent years. Particularly striking in this connection is the high degree of enrichment of the concentrates from magnetic iron-ores which is now commercially feasible. Magnetic concentrates containing from 6 7 to 139 per cent. of metallic iron, showing an efficiency of 90 and even 95 per cent. in. their separation, are not now uncommon. Such results exceed those obtained by gravity methods of treatment of all copper-, lead-, and zinc-ores, and are only equaled in the cyaniding of gold-ores and in the flotation treatment of certain copper-ores. It is of interest to note that the-type of magnetic field which is employed in securing these results, in the Gröndal (wet) and the Ball & Norton (dry) systems of treatment is the same in each case : viz., a field of alternating north and south poles. The credit for developing this simple and useful field, which has found so wide an application both in this country and abroad, is due to two American inventors and engineers, Clinton M. Ball and Sheldon Norton. At the same time, it should be noted that part of the improvement in the grade of the magnetic concentrates, especially in the case of the wet treatment of finely mineralized ores, is due to a well-devised scheme of mill-treatment, whereby a rough concentrate is usually obtained as an intermediate product, which is then recrushed and reseparated in obtaining final clean products.

Jan 3, 1913