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By G. M. Roberts

During the six years that the writer was connected, as chemist and chief assayer, with the Proprietary Mines, Broken Hill, N. S. W., several interesting experiments were made in the sampling of the silver-lead bullion obtained from the waterjacket smelting-furnace.

Jan 1, 1899

By B. M. Harra, F. G. McCutcheon, O&apos

Until about 1930, the universal practice of horizontal-retort zinc smelters in the United States, as far as the writers are aware, was to operate the retort furnaces on a 24-hr cycle; that is, the retorts were charged in the early morning of one day, and in the early morning of the following day the residues were cleaned out, the retorts recharged, and a new cycle started. During the business depression of the early thirties, zinc production fell off to the extent that zinc smelters had idle retort capacity. Rather than continue to run some of the retort furnaces on a 24-hr cycle and shut down the remainder, a few companies decided to try out a longer cycle. Although the output of zinc per retort per day is lower, the longer cycle permits a larger charge per retort and improved zinc recovery. Advantages of the longer cycle were soon evident, and the practice spread rapidly. Various lengths of cycle were used, typical examples being 28-hr, 32-hr, 36-hr, and 48-hr. The 48-hr cycle fits in best with the standard routine of smelter practice that was built up on the basis of the 24-hr cycle; that is, the retort furnace "maneuver" always comes at the same time of day, and can be performed in the cool hours of the early morning. Under some conditions, particularly in some of the older plants, where the retorts are smaller than in newer plants, a 48-hr cycle is longer than necessary, and some intermediate length of cycle may theoretically be most economical. Use of an intermediate cycle, however, means that the maneuver comes at different times on consecutive days, and that sometimes it comes during the hottest part of the day. The work on the retort furnaces is extremely hot and arduous at best, and it is much worse, of course, if it is done during the heat of a summer day. When labor was plentiful and tractable, many plants were able to operate on cycles of intermediate length, but the workmen did not like the working hours. Under present labor conditions, it is hardly practicable to operate with a cycle of intermediate length, so the choice has narrowed down to the alternatives of 24-hr or 48-hr cycles. In any discussion of economics, too comprehensive generalization is not warranted, because local conditions affecting economics vary greatly. The best economic practice at one plant at any given time may be uneconomical at another plant, or even at the same plant at another time. To determine the length of cycle that is the better practice at a given plant at a given time requires a weighing of the advantages and disadvantages of each cycle, taking into consideration all the local conditions. some of the factors that must be considered in making the comparison are discussed briefly in the following paragraphs.

Jan 1, 1949

Recognizing the fact that the problems of the committee named by the Board to prepare the "official ticket for officers and Directors of the Institute are various and difficult; and desiring to assist this committee by setting forth some of the principles that should guide the committee and some of the qualifications that should be required of candidates, the following instructions are formulated and the Secretary is directed to publish them in MINING AND METALLURGY concurrently with the publication of the names of each newly appointed Nominating Committee and to send a copy to each member of the Committee.

Jan 1, 1937

By R. D. Nelson, D. H. Polonis

ThE eutectoid decomposition of 6 phase in the Cu-Sn system (32.53 wt pct Sn) has been studied by several investigators.1-6 On the basis of X-ray work, Iball and 0wen1 reported complete decomposition of 6 in powder specimens after 7 days at 300°C. Wang and Hansen followed the micro-structural changes during heat treatment of lump specimens and estimated 5 pct decomposition after 63 days at 300°C. Wang and Hansen suggested that the discrepancy between the decomposition rates of powder and lump specimens might be due to the excess surface free energy of powders. The present work involved 6 decomposition in copper-tin alloy powders containing 32.6 wt pct Sn. Alloy lump specimens exhibited entirely 6 phase after fairly slow cooling (air cooling) from above 350°C and were so brittle that they could be easily crushed to-200 mesh in a percussion mortar. X-ray diffraction study of the as-crushed powders (-200 mesh) revealed 100 pct 6 phase with very slight line broadening effects due to strain introduced by crushing. Only 6 phase was detected by X-ray diffraction in powders which were heat treated 4 hr at 450°C and air cooled to room tem-

Jan 1, 1960

By J. J. Reuther

Reported are singular results of a completed combustion research program designed to reliably determine the ignition, burnout, and pollution characteristics of various ranks of pulverized coal (bituminous and lignite), chars, and water-slurries of the raw bituminous coals. Well controlled simulated boiler environments were diagnosed to do so. The standardized, systematic, and comprehensive investigation established relationships between physicochemical fuel properties (coal rank, volatile matter, and reactivity) and thermochemical combustion behavior (ignition and burnout times, and NOX pollution potential) for 31 different fuels.

Jan 1, 1985

By John Birkinbine

The favor with which the members of the Institute received Mr. Fernow's paper upon the use of charbon roux in the manufacture of iron has encouraged me to present this paper, in the hope of having the discussion upon the manufacture and use of the oldest and undoubtedly the best fuel for producing pig iron continued. Owing to the advances made in employing anthracite coal, bituminous coal, or coke, or mixtures of them, we are apt to forget how much of our present development is due to the pioneers in iron manufacture and the fuel which they employed in the production of pig iron. In Mr. Swank's last compilation of the iron and steel works of the United States, the furnace capacity of the country is given as 5,868,000 tons, of which 1,000,000 tons can be made in the 264 charcoal furnaces. In other words, over one-third of the furnaces now in existence use charcoal for fuel, and produce more than onesixth of the iron made. If to this is added the 130,000 tons of blooms and billets turned out by the 122 forges and bloomaries, the importance of the charcoal industries will be appreciated.

Jan 1, 1879

By B. E. Fernow

In order to ascertain to what extent the mining industry has been dependent upon forest-supplies, for the purpose of a report upon

Jan 1, 1889

By Thomas P. Meloy, Duane T. Eppler

The science of particle shape analysis has expanded rapidly in the decade since precise numerical-statistical techniques were developed for use in characterizing the shape of closed forms. Use of Fourier descriptors permits shape to be quantified to whatever degree of precision is required. With this technique, particles and particle systems can be compared either on the basis of shape characteristics displayed by individual particles, or on the basis of aggregate shape characteristics representative of large samples of particles. Shape characterization work completed to date has shown that the physical characteristics of particle systems (porosity, permeability, strength, mechanical stability, chemical reactivity, and flow characteristics (viscosity)) are related directly to particle shape. Furthermore, it has been shown that particle shape is a function of chemical composition, process of formation, and post-formational history of the particle. In this light, particle shape analysis has potential applicability to a host of engineering and industrial problems encountered in processing particulate material. It can be used to optimize the efficiency of separation processes and particle feed systems, to trace particle pathways through processing systems, and to monitor the operation of specific processes, the wear of critical machine parts, and the quality of end products in processing systems. In this paper we discuss these specific applications of shape characterization to particle processing.

Jan 1, 1980

By R. L. Tobie, H. W. Seaney

Over the years since 1956 when initial experiments were conducted on underground concreting in an attempt to cope with the ground weight and pressure encountered in the development of a large-scale underground block caving system, the use of monolithic concrete linings has grown to include most of the primary development in the mining area. Although the development cost of concrete linings is higher than either timber or steel-supported openings, the repair and maintenance costs are substantially lower, making concrete the most economical means of ground support. Other ad- vantages are also apparent, in that concrete provides superior fireproofing, better ventilation, and a safer, cleaner working place.

Jan 11, 1965

By Henry B. Fernald

THE Federal income tax treatment of expenditures for exploration and development for mines and other natural deposits (other than oil and gas) was materially changed by special provisions of the 1951 Act that are continued in the present 1954 Code." These present provisions for mines in stance they are the same as the 1951 amendments to the 1939 Code, Secs. 23 (cc) and (ff), respectively, except that for exploration the allowable annual deduction is increased to $100,000 (from $75,000) and minor changes in case of property transfers are made with respect to the four-year limitation. Before 1951 the statutes made no specific pro- visions regarding development and exploration for mines, but the rules were prescribed by Treasury regulations: 1) Before the mine entered the production stage, all development and exploration expenditures for mines, less net receipts, were to be capitalized recoverable through depletion or written off as losses when determined worthless. 2) After a mine entered the production stage, development expenditures were deductible as expenses-currently if ordinary expenses, but on a deferred basis if extraordinary in scope. This recognized the two separate periods, one before and the other after beginning of the production stage. There was no distinction between an exploration and a development period, but exploration was included as part of development.

Jan 1, 1958

By J. A. Snyder, W. L. Finlay

SEVERAL notable studies of the effects of sub- stitutional solutes have been reported. Outstanding among these for its elucidation of general principles, is the summarized work of Hume-Rothery and coworkers.1 For a systematic study of the effects of substitutional solutes on the mechanical properties of the solvent lattice, the work of Brick, Martin, and Angier² on copper; of Frye and coworkers³,4,5 on copper and silver; and of Lacy and Gensamer6 and of Austin7 on iron may be mentioned. Titanium is one of the few elements offering the possibility of a similar study of interstitial solutes since, unlike most metallic elements, it exhibits extended solid solubility for most of the interstitial solutes—hydrogen, boron, nitrogen, oxygen, and carbon. This paper reports a survey of the effects of dilute solutions of nitrogen, oxygen, and carbon on the mechanical properties of high-purity alpha titanium. Previous Work: Van Arkel and De Boer showed" that high purity titanium was quite ductile and De Boer, Burgers and Fast established".' that not only were oxygen and nitrogen very soluble in solid titanium but that, long before the limit of solid solubility of either had been reached, these interstitial solutes rendered the metal brittle. Their electrical resistance data as a function of

Jan 1, 1951

By J. M. W. Mackenzie

The rheological properties of aqueous solutions of several commercial flocculants were investigated using a rotating coaxial cylinder viscometer. Similarities between the pH-apparent viscosity relationship and the flocculating properties of the reagents are discussed here. Synthetic neutral polymers and polyelectrolytes are used extensively as flocculants in mining and chemical engineering operations. The action of these reagents has been interpreted as adsorption of the polymer flocculant to the mineral surface, followed by the formation of physical polymer bridges between the particles.4,5 A consequence of the bridging model is that the efficiency of a polymer flocculant depends on the degree with which the polymer is adsorbed to the mineral surface, and the extent to which the polymer molecule forms a bridge between colliding particles. The length of the polymer molecule and its orientation at the mineral surface are important in the bridging mechanism since the further the polymer segments can protrude from the mineral surface the greater the probability may be of these segments contacting another mineral particle. Linke and Booth7 have shown that, for a silica suspension, both the settling rate at a given polymer addition and the maximum settling rate obtainable increase with increasing molecular weight. The analysis of silberbergl0 has

Jan 1, 1964

By R. C. Ellman

In the United States, the consumption of lignite and subbituminous coals is increasing. A variety of energy-oriented companies have leased large blocks of reserves, new large power plants are in operation and being constructed, and new producing mines are being developed. The Bureau of Mines has maintained an active interest in the utilization of low-rank coals for many years. In 1951, with the completion of the Bureau's Grand Forks Coal Research Laboratory, an organizational unit was established for studies in lignite preparation. Since that time, numerous investigations have been completed. This research has dealt almost exclusively with lignite, but since subbituminous coals have many similar characteristics, the findings can often be applied to both types of coal.

Jan 1, 1970

NAME AND OBJECT. SEc. 1. This Institute is incorporated under the Membership Corporations law of the State of New York ; its corporate name is American Institute of Mining Engineers; and its objects are such as are stated in its Certificate of Incorporation. ARTICLE II. MEMBERS. SEC. 1. The membership of the Institute shall comprise four classes, namely 1. Members ; 2. Honorary Members ; 3. Associates ; 4. Junior Members. All members shall be equally entitled to the privileges of membership, except¬ing that Honorary Members, Junior Members, and Members and Associates whose residences shall be outside of the United States, Mexico, and Canada shall not be entitled to vote. Members and Associates residing within the United States of America, Mexico, and Canada, and not in arrears for dues, shall be entitled to vote in person at the meetings of the Institute, or, as hereinafter provided for, by letter ballot. SEC. 2. The following classes of persons shall be eligible for membership in the Institute, namely : as Members, all professional mining . engineers, geologists, metallurgists, or chemists, and all persons actively engaged in mining and metal¬lurgical engineering, geology, or chemistry ; as Associates, all persons desirous of being connected with the Institute who in the opinion of the Board of Directors are suitable.

Jan 1, 1923

By Zden[e]k P. Bažant

Due to their heterogeneity, most rocks fracture with a zone of distributed cracking ahead of the fracture front. This makes linear elastic fracture mechanics inapplicable. The present study describes a mathematical model in which the progressive microcracking is taken into account by strain-softening stress-strain relation. In a simpler version of the model, the triaxial strain-softening stress- strain relation is obtained by direct adjustment of the elements of the compliance matrix. This formulation is rigorous only if the principal stress directions do not rotate during fracture formation within the fracture process zone. As a more sophisticated and generally applicable model, the so-called microplane model which is an analogue of the slip theory of plasticity is outlined. Comparison with fracture data for various rocks are given.

Jan 1, 1984

By F. H. Daniels

IN this paper it is my intention to call your attention to a few of the many producers using blast, now in common use in Sweden, and also those constructed by the Washburn & Moèn Manufacturing Company at their Quinsigamond Works. During a prolonged stay in Sweden the writer had an opportunity

Jan 1, 1881

By James J. Olson, Richard A. Dick

Blasting practices have shown a recent trend toward larger blastholes and larger burdens and spacings, although some operators, after reconsidering the situation have gone back to smaller blasthole sizes. The greater pull-down capabilities of larger drill rigs and the greater bearing strength of large diameter drill bits give penetration rates for large diameter blastholes approaching, and sometimes exceeding, penetration rates for smaller holes. In practically all cases, large diameter holes can be drilled more quickly and cheaply, based on volume of hole, than small diameter holes. The industry's shift to dry blasting agents and slurries, products which perform more dependably and efficiently in larger diameters, gives an additional advantage to larger boreholes.

Jan 3, 1972

New Products Equipment

Jan 6, 1953

By M. E. Hassan, J. C. Calhoun, R. F. Nielson

An apparatus was constructed for the measurement of inter-facial tensions over a range of temperatures and pressures. This apparatus utilized the pendent drop method, and resembles in construction similar apparatus recently described in the literature and in use in some petroleum research laboratories. The interfacial tensions of benzene, propane, n-pentane, n-hexane. n-octane. and iso-octane against water were measured at temperatures ranging from 26" to 82" C and at pressures ranging from 1 to 204 atm. Values of interfacial tensions for the henzene-water system and their variations with temperature and pressure are generally in good agreement with value? of previous investigations. The data in all cases showed a slight decrease of interfacial tension with pressure at constant temperature in the range studied. The effect of pressure became less as the pressure was increased, with an indication of a reversal of the effect at higher pressures. There was a decrease of interfacial tension with temperature at constant pressure in all cases, as would normally be expected. This rate of decrease became greater the higher the temperature. A general equation is presented for the interfacial tensions as a function of presPurp and temperature over the range studied, and the constants calculated for each system. A definite trend was found in the effect of molecular weight on the interfacial tension at a given temperature and pressure, for the homologous series from propane to n-octane. Data for n-decane from the literature fitted well into this trend. INTRODUCTION It has been recognized for many years that surface forces play an active part in the production history of an oil reservoir as well as in determining the amount of unrecoverable oil. The magnitudes of these forces are governed by the values of the interfacial tensions. These vary greatly with composition, pressure, and temperature. The effect of composition is greater than that of pressure and temperature over the ranges normally encountered. In fact, because of the variety of compounds present in a crude, no attempt has yet been made to correlate crude composition with its surface tension or with its interfacial tension against water. The amount of dissolved methane greatly affects the surface properties of an oil, and there are "surface-active" compounds in crudes which have a much greater effect on boundary tensions than do equal amounts of hydrocarbons. The purpose of the present work was partly to contribute data that would eventually be used in correlations applicable

Jan 1, 1953

Jan 1, 1966