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By K. Huessener

Discussion of the paper of K. HUESSENER, presented at the New York. meeting, February, .1916, and printed in Bulletin No. -110, February, 1916, pp. 443 to 474. KARL NIBECKER, Youngstown, O.-It has been contended that the method of measuring the operation of a blast-furnace boiler plant by means of the amount of steam generated per pound of coke used in the blast furnace is not of any value and even that it is quite misleading. It has been found, in the plant with which I am connected, that, in general, a blast furnace will operate during a month so close to average. conditions that the average monthly measure of the plant efficiency is indicated by the number of pounds of steam made per pound of coke put into the furnace, neglecting the amount of iron made and the amount of gas used for heating the stoves. For some time, it has been our custom to keep a record of this figure and use it as a general indicator of the operating practice. In comparing this figure from two different plants we have found some difficulty, due to differing conditions. It is conceivable but not altogether probable that a slight difference in burden, kind of ore or coke, would account for this difference. The method of using the gas, whether washed or unwashed, and the plant arrangement, may affect this number. For several plants on which we have worked up this number, we have found that most of the ordinary running irregularities are eliminated during a run of a month or more and that the number is, therefore, satisfactory. In connection with a plot of the number of pounds of steam generated per pound of coke, we are also plotting the production of the furnaces and the pounds of coke used per ton of production. With these three curves plotted on the same sheet, we believe that the operating man has sufficient information to judge of the efficiency of his plant' for any month.

Jan 5, 1916

By F. J. Longworth

For a number of years an intensive study has been made to improve the blast-furnace practice at Copperhill not only as to costs but to provide a good grade of gas for the acid plants. This study, took us back to the fundamentals of successful pyrite smelting; namely, a blast furnace working on a clean sulfide ore, free from fines, and the use of quartz high in silica as a flux. In 1919, the quality of the flux was improved and its effect on the metallurgy was very marked. To improve the practice further, it was necessary to work out some method of treatment for the sulfide fines and the siliceous and refractory ores, other than in the blast furnace. A series of milling tests indicated that these products could be successfully treated by differential flotation, and in 1922 plans were made and a flotation plant built. It was estimated that the flotation plant would deliver to the smelter 40 to 50 tons of concentrates per day; the problem was what to do with these concentrates. It was out of the question to attempt to smelt them in a blast furnace because of the dust losses and, because our practice demands a charge free from fines for satisfactory operation. There is no custom smelter in the vicinity to which concentrates may be sold, pending the time when the tonnage will be sufficient to warrant roasters and a reverbatory furnace. Sintering and nodulizing were investigated but neither method fitted into our scheme of metallurgy. A close study of the converter practice was then made to see if some method could not be evolved to smelt this tonnage of concentrates in a converter without preliminary treatment. At that time, the converter installation consisted of two 12-ft. Great Falls converters, which were handling 12 to 14 per cent. matte. The heat balance of the converters working with 12 to 14 per cent. matte was more than sufficient to smelt the contemplated tonnage of concentrates but the mechanical difficulties. of feeding fines into the Great Falls converter made the use of this type of converter impractical.

Jan 9, 1924

By O. N. Mohanty, S. Mohan Rao, N. D. Rao, T. Mukherjee, P. V. T. Rao

"Chromite ore is an indispensable raw material in the manufacture of ferro-chrome and charge-chrome, which are used for the production of stainless and other alloy steels. The demand for chromite ore is ever increasing because of increasing consumption of these steels. Keeping this in view, Tata Steel is keen to recover values from fines and wastes, and also to produce value added products from their captive chromite mines and its processing plants.Tata Steel has its captive chromite resources at Sukinda, Orissa. They contain two ore types, i.e. (i) Ferruginous and (ii) Siliceous. The generation of off-grade ores is an increasing trend and simultaneously customer quality requirements are becoming ever more stringent. The ferruginous type ore also contains a considerable quantity of in-situ fines (~20% particles below 0.5 mm) that compound the beneficiation problem.In many places, in India and abroad, mined non-marketable off-grade and low grade chromite ores are upgraded by using either simple classification techniques like screw classification, hydrosizing, hydrocycloning or conventional gravity concentration processes such as Heavy media separation, Jigging, Spiraling, Tabling etc.At Tata Steel, the ferruginous type ores are treated in Chrome Ore Beneficiation (COB) Plant that comprises: a crushing and grinding circuit; a classification circuit using hydrocyclones; and a beneficiation circuit using 4 stage spirals in the coarse circuit (-0.5+0.1 mm) and 3 stage spirals & tables in the fine circuit (-0.1+0.038 mm). In this process, 3 types of tailings are being generated and together analyses about 17 % Cr2O3, which is high. From the present operation the chromite recovery is around 70% and could not produce coarse concentrates (+0.5 mm size). Whereas the siliceous type ore is treated in the Lumpy Ore Processing (LOP) plant, consisting of crushing-washing & classification-hand sorting operations, to produce marketable grade lumpy ore and –10 mm de-slimed fines. These fines are intermittently treated in the COB plant. The higher silica content (greater than 1%) and low Cr/Fe ratio (less than 2.8) are the problems with these concentrates."

Jan 1, 2003

By Eckley B. Coxe

IN the anthracite coal regions of Pennsylvania the custom has been to sight either at an open light (generally a mine-lamp), or at the string of a plumb-bob. If the station was intended to he a permanent one, a spud, as it is called, that is, a nail resembling a horseshoe nail with a hole in the head, is driven into the timbers over the station, or, if there be no timber, a hole is drilled in the coal or rock roof, into which a wooden plug is driven, which serves to hold the spud. The first operation in making a survey is to lay out the stations, that is, to mark the place where the holes are to be drilled for the plugs or the points on the timbers where the spuds are to be driven in. This should be done before any instrumental work is begun, as much labor can generally be spared, and the use of very short sights can often be avoided, by carefully laying out the stations beforehand. When the stations were laid out, a plumb-bob was hung from the innermost spud, which I will call No. 1, the instrument was put in position at No. 2, by plumbing down and putting a centre-pin under the spud, and then setting up over the centre-pin, and another plumb-bob was suspended from No. 3. If great accuracy was not required, a mine-lamp was set up under the plumbbobs, at No. 1 and No. 3, and the engineer sighted at them. If great accuracy was required, a lamp or some white sbface was held by an assistant behind the strings of the plumb-bobs. To work with any speed by the latter method (i. e., the accurate one), it was necessary for the engineer to have three assistants on whom he could rely even when the chaining was done afterwards; viz. : one to hold the light behind the string at No. 1, one at No. 3, and an assistant at the instrument to hold the light while levelling, reading the in

By Eckley B. Coxe

IN the anthracite coal regions of Pennsylvania the custom has been to sight either at an open light (generally a mine-lamp), or at the string of a plumb-bob. If the station was intended to be a permanent one, a spud, as it is called, that is, a nail resembling a horseshoe nail with a hole in the head, is driven into the timbers over the station, or, if there be no timber, a hole is drilled in the coal or rock roof, into which a wooden plug is driven, which serves to hold the spud. The first operation in making a survey is to lay out the stations, that is, to mark the place where the holes are to be drilled for the plugs or the points on the timbers where the spuds are to be driven in. This should be done before any instrumental work is begun, as much labor can generally be spared, and the use of very short sights can often be avoided, by carefully laying out the stations beforehand. When the stations were laid out, a plumb-bob was hung from the innermost spud, which I will call No. 1, the instrument was put in position at No. 2, by plumbing down and putting a centre-pin under the spud, and then setting up over the centre-pin, and another plumb-bob was suspended from No. 3. If great accuracy was not required, a mine-lamp was set up under the plumb-bobs, at No. 1 and No. 3, and the engineer sighted at them. If great accuracy was required, a lamp or some white surface was held by an assistant behind the strings of the plumb-bobs. To work with any speed by the latter method (i. e., the accurate one), it was necessary for the engineer to have three assistants on whom he could rely even when the chaining was done afterwards; viz.: one to hold the light behind the string at No. 1, one at No. 3, and an assistant at the instrument to hold the light while levelling, reading the in-

Jan 1, 1873

By Peter Heine

Diavik Diamond Mines Inc. (DDMI) has treated systems development as an integral part of the construction project when it built Canada?s second diamond mine. Fully aware that the proper collection and processing of operational data is needed to drive business decisions during production and planning, key Performance Indicators (KPIs) were defined to effectively manage operations when the mine went into production. The Production Information Management System (PIMS) allows KPIs to be measured, reported, and transferred to other systems in a reliable and convenient manner. PIMS provides a mechanism to collect real time production data from the various control systems around the site and acts as a tool to ?drill-down? and establish the important cause-effect relationships that impact the value of a KPI. Thus PIMS provides a data collection, storage, management, and an environment in which cause-effect relationships can be analysed and statistically verified. This understanding of the real cause-effect relationships, close to the source of the data and in the context of the operation, can be used to improve both operations and maintenance performance. The PIMS includes the PI Database implementation, its associated external interfaces with the various Control Systems, Cleaning Packaging Weighing System, Environmental System, Enterprise Asset Management (EAM) System, and Diamond Tracking System (DTS), as well as laboratory data collection, custom applications (downtime tracking, data reconciliation) and user clients. The interface with the EAM system provides material flow quantities and equipment availability on which the plant performance reports are based. The transfer of equipment usage to the EAM system is fed into the maintenance notifications and work orders functionality in the EAM. The environmental system interface provides the mechanism for capturing water consumption data required to generate the various regulatory reports. The interface to the cleaning-packaging-weighing system provides the mechanism for capturing batch data for transfer to the DTS for diamond product tracking at the production splitting facility in Yellowknife. The PIMS lab application provides a means of getting sample data into the system for critical metallurgical metrics, and the data reconciliation application provides a means of manually verifying the data before it is published or passed onto other systems.

May 1, 2003

By C. J. Delisio

The basic concept of tunnel boring has not changed since the late 1800's. R. Stanley of Great Britain obtained a Canadian patent as early as December 1891. Mr. Stanley's machine was a device that consisted of a rotating wheel equipped with drag-type teeth; it had a means of thrusting the cutterhead against the face or heading; it had a means of clamping or gripping the machine in its bore; it had a means of collecting and depositing the cuttings into a screw-type conveyor located near the invert of the tunnel. It even had a means of varying the speed of the forward motion of the machine to suit different hardnesses of rock encountered. This description essentially fits the latest tunnel-boring machines being built today. In short, there has been no significant advance in the basic concept in 70 to 80 years. It may well be that no significant change can be expected for some time into the future. Today's machines, while still basic in concept, offer many advances aimed at faster tunneling. Among these are 1 ) improved cutters, 2) guidance and steering devices, 3) dust-control devices, and 4) mechanisms to aid in installing tunnel supports. CUTTERS The most important part of a hard-rock tunnel borer is the cutter. If the cutter can cut the rock, it is a boring machine. If the cutter cannot cut the rock, no other part of the machine can. When Jarva, Inc. decided to build a machine, the first problem was to find a good cutter. In our search, we looked at most of the cutters on the market. We selected Reed Drilling Tools' cutter because the design of their cutter was aimed at hard-rock tunneling. We feel that they build the best cutter available and provide the best possible service to their customers. As tunnel-boring machine design advanced, the transition from drag bits to roller bits was natural because harder formations required a roller bit, and it is the goal of all mole users to bore harder formations. Roller bits

Jan 1, 1970

By Travis A. Shoemaker, Mitchell S. Youmans, Nancy T. Chin, Michael S. Senior

A geologic assessment and stability analysis of the right abutment of Boundary Hydroelectric Dam in Pend Oreille County, Washington was completed in May 2017. The stability analyses identified a potential failure plane of a rock block that supports a bridge abutment, and weight restrictions were established to reduce the bridge loads. To restore full use of the bridge, a long-term stabilization solution was designed. A two-phased construction approach was implemented to reduce risk: (1) cable lashing and wire mesh and (2) 24 permanent post-tensioned tiebacks. The tiebacks were located and sequenced based on stabilization effect and site access to incrementally ease the bridge loading restrictions throughout construction. Due to weight restrictions and site tolerances, all work was performed with rope access construction methods. The contractor’s means and methods, tight drilling tolerances, and an exploratory adit within the rock block made the construction uniquely challenging. Due to limited exploratory data and irregular rock face geometries, the design orientation, location, and tolerances of the tiebacks were established in a 3D Building Information Model (BIM). The 3D model was revised frequently during construction to 1) model the as-drilled conditions of the tiebacks; 2) compare with the remaining proposed anchors; 3) anticipate the contractor’s sequence to reduce risk during drilling; 4) accommodate the contractor’s requests for information; 5) make design changes based on field observations; and 6) incrementally assess rock block stability. The 3D model was created using BIM software and automated using custom programming to link per-plan, proposed, and as-installed tiebacks between the 3D model, field logs, and a stability analysis. This system allowed for a near real-time 3D model and stability analysis, which were easily communicated between the design team and field staff. This workflow and automated model nearly eliminated manual editing of the 3D model, accelerated contract document response time, and helped reduce risk for the owner, contractor, and engineer. Here, we present a successful case study utilizing the Observation Method and a real-time 3D model to complete a project with numerous complexities relating to design, communication, and risk.

The opening session* was held in the hall of the Franklin Institute, on Tuesday evening, June 20th, President Holley in the chair. The President introduced Mr. Franklin B. Gowen, who addressed the Institute as follows: Mr. President and Gentlemen : It has been made my pleasant duty to welcome you to the city of Philadelphia, but in so doing I shrink, with some natural reluctance, from appearing before an audience so much better fitted than I am to cope with the subjects which are usually presented to your association, and I can assure you that no trembling neophyte, first venturing within the groves of the Academy, or walking, with sacred reverence, in the gardens of Plato, felt more natural dread at the consequence of his own temerity than I do in appearing before an audience composed of geutlenlen belonging to a scientific society of which I am but too sensible that until now I have been a member only in name. In olden times, upon entering a temple sacred to the worship of any deity, it was customary to lay some offering upon the altar, and, in following this custom, it will be my duty, before entering upon the more pleasant part of the task which is assigned me, to call your attention to a subject with which I have been somewhat familiar, and which is entirely within the scope of your investigations, in the belief that I may throw out some hints or some suggestions of a process that may be fully developed by some of you, and eventually lead to the introduction of that which may be of service to the human race. The satirist who described the philosopher whom he met, as engaged in the process of extracting sunbeams from cucumbers,

By M. C. Roberts

The consumption of industrial minerals, like most other commodities produced from the earth, depends on the demand for the goods and services that use these materials. Minerals are not generally used directly by final consumers (table salt is a notable exception) but instead are used to either make products that are then purchased by customers, or the minerals are used to make industrial products that eventually contribute towards producing other goods and services. Therefore the demand for industrial minerals in most uses is derived from the ultimate demand for goods and services by consumers. The problem for producers of industrial minerals is that the demand for their mineral product fluctuates greatly in response to the changes in the production of goods and services over the course of the business cycle. In this respect, the producers of industrial mineral are innocent victims, subject to market fluctuations outside of their control. Because the demand for most minerals depends on the demand for the product and because minerals typically make up a minor portion of the costs of producing the product, changes in the price of the mineral often do not influence demand for it to a significant degree in the short run. This is described as a very low price elasticity of demand, as shown by the steep slope of the hypothetical demand curve in Figure 1. This demand curve shows that changing the price of the mineral does not alter the quantity demanded very much, but shifts in the demand curve will be the important determinant of the quantity of the mine.ra1 that is sold. The shifts are caused by the changing demand for the products using the mineral over the course of the business cycle.

Jan 1, 1994

By A. L. Blomfield

THE Golden Cycle Mining and Reduction Co. operates its custom mill at Colorado Springs on Cripple Creek ores exclusively. These ores are straight sulpho-tellurides, with practically no base metals such as Pb, Cu, Zn, As, or Sb. Upon entering the mill, the ore all passes through the sampler to storage bins, where beds of 5000 tons each are made to insure uniformity in roasting. CLASSIFICATION OF ORES For efficiency, it has been found advisable to separate the ores into two classes according to their line content. Other constituents have their effect, such as alumina and magnesia, but, speaking generally, these are roughly proportional to the line, which, as CaO, is used as the indicator. Class A contains not more than 2 per cent. CaO and comprises about 66 per cent. of the ore treated. Class B contains over 2 per cent. CaO, and comprises 34 per cent. of the ore treated. Typical analyses of both classes are as follows: Class A Class B Insol 56.70 75.90 Al203 2.30 3.40 Fe 3.26 3.48 CaO 1.57 5.12 S 1.79 1.80 Mg0 0.21 1.08 Ignition loss 3.20 6.50 99.03 97.28 The beds of each class of ore are made as large as possible with the available ore as it comes in, to avoid changing from one bed to the other any oftener than necessary. Each roaster will handle 50 percent. more of class A ore than of class B, with practically the same results. This necessitates changing the rate of feed for each new bed and tends toward a poor roast and loss of tonnage at each change.

Jan 8, 1918

By W. E. Bruce, R. J. Morrell, James Paone

This chapter is a partial summary of an investigation by the U.S. Bureau of Mines (USBM) made in response to a recent request by the Assistant Secretary, Water and Power Development of the U.S. Department of the Interior, for a comprehensive review of horizontal boring technology related to underground power-line installation. This review is concerned primarily with 3 to 36-in. diam horizontal holes from several hundred to several thousand feet in length. An electric power system consists of three essential functions: generation, transmission, and distribution. The generation component includes the generating station and step-up substation; the transmission component includes the transmission line and stepdown substation at typical voltage levels ranging from 69 to 345 kv for underground lines and 69 to 500 kv for overhead transmission lines; the distribution component includes the distribution line carrying the commonly used voltages of 120, 208, and 240 v, the distribution transformer, and the line to the service customer.l The Federal Power Commission reports that 1600 miles of underground transmission lines of 60 to 345-kv capacity are now in service in the United States. By 1980, it is estimated that approximately 3000 miles of trans- mission lines will have to be placed underground.2 The cost of burying electric transmission lines underground in metropolitan areas, approximately 30 miles from the center of each of the most populated cities, will exceed $1.5 billion with the methods now available. The wide spread in unit costs of overhead and underground transmission lines narrows as right-of-way costs for overhead transmission in congested areas increase. Improved methods of underground emplacement will certainly reduce this difference in costs and even further favor underground emplacement. Also, in the future, overhead transmission lines will probably not be permitted in highly built-up areas.

Jan 1, 1970

By R. B. Moore

Page History................................ 708 What is Radioactivity?........................ 710 Disintegration Series.......................... 711 Radium Ore Deposits......................... 713 Metallurgical Treatment........................ 717 Methods of Ore Concentration..................... 722 Future Supply of Ore......................... 723 Uses of Radium............................ 723 Mesothorium as a Substitute for Radium................. 724 Discussion.............................. 725 Probably no other metal excites as much interest, among both scientific men and the general public, as radium. This is due partly to the high cost of radium salts and partly to the peculiar properties of the element. Since radium-bearing ores were discovered in the United States, the interest of American scientific men has been stimulated and, at the present time, more radium is extracted and refined in this country than in all the rest of the world together. HISTORY The property of radioactivity was discovered, partly by accident, by Henri Becquerel, the French physicist, in 1896. He was experimenting with certain fluorescent substances in order to find, if possible, a connection between fluorescence and the recently discovered X-rays. Among other chemicals which possess the property of fluorescence, he was using salts of uranium. His custom was to expose the fluorescent substance to the action of sunlight and then register the effect of possible penetrating radiation on a photographic plate protected from ordinary light. Bec-querel's experiments gave positive results at once, and he at first believed that he had discovered a relation between fluorescence and X-rays. Later he exposed a plate to a uranium salt which had not been previously exposed to sunlight. To his surprise, on developing this plate, he found that he had obtained the same effect as he had previously secured when

Jan 1, 1919

By H. M. Howe

(New York: Meeting, October, 1913.) 1. INTRODUCTION.-This paper gives the results of our micro-graphic determinations of the position of Ae3 in a series of 14 hypo-eutectoid steels of varying carbon content, one of them very rich in phosphorus, and of SEe for one hyper-eutectoid steel. We have pro-ceeded chiefly by noting the temperature -at which the reabsorption of the pro-eutectoid element is found to be complete after a 30-min. holding, but in part also by noting the temperature at which its precipitation begins. Observations on these same steels by Messrs. Burgess, Crowe, and Rawdon, of the United States Bureau of Standards, are given in a paper' issued simultaneously with this, while in a third paper s one of us compares these data with those of earlier observers. These three papers are treated as one whole by numbering their sections, tables, and illustrations continuously, and by setting the folding plates of micrographs at the end of the last paper. THE COMPOSITION OF THE STEELS EXPERIMENTED ON is given in Table I. Notation. and Definitions.-Following Osmond's development of Tschernoff's notation; in which " Ac3 " is the upper limit of the hypo-eutectoid part of the transformation range as observed in heating up, and " Ar3 " is that same limit as observed in cooling down, and following the usual custom of calling the upper limit of the hyper-eutectoid part of that range "SE," we may go farther and call this latter limit " SEc " when observed in heating up .and " SEr " when observed in cooling down.

Jan 6, 1913

During the past decade, since the appearance of Popoff's (1966) review of grade tonnage calculations, it has become evident that defining a new method which could be followed step by step by a technician and which would improve reserve estimation was not a simple thing to do. Some concepts have emerged though, and most definitions of ore reserve now require a statement of reliability (USGS, 1975; and Zwarten-dyke, 1976). Exactly how the reliability should be computed is not a straightforward process. It also became apparent that not only was reliability a requirement but that additional questions such as how to predict mining re- serves from geological reserves were to be asked. In fact what became obvious is that specific models have to be designed for each type of mine and for each type of question which is asked. Most methods can be encased within a unique general geostatistical, model, but it takes considerable custom tailoring, and there are still questions that are left unanswered. In this chapter, before giving techniques, we intend to first review what should be required from a grade tonnage calculation done at the exploration stage. If the final objective is still to specify a tonnage and grade, with eventually a reliability, many qualifications have to be made before quoting, and of course, calculating these two numbers. Then the currently avail- able methods will be reviewed and future trends will be shown; finally a few case studies will be given and recommendations about the choice of a model will be made.

Jan 1, 1979

The LeadtZinc Concentrator at Mount lsa treats all the lead-zinc-silver ore from the Mount Isa Mine and some of the ore from the Hilton Mine. This concentrator was commissioned in June 1966 and total lead-zinc-silver ore treatment was transferred from the Mount rsa's original No 1 Concentrator in May 1967. Plant capacity is around 5 x 106 t/y.There have been three phases of major plant modifications since commissioning:1. replacement and upgrading of the flotation section in 1979; 2. upgrading of the crushing plant and installation of a heavy medium hydrocyclone plant in 1983 for ore preconcentration, and; 3. doubling ball milling capacity and a further upgrading of the flotation section in 1992.Other developments have included the installation of flotation columns and Jameson cells.The evolution of milling practice since 1955 has been reported by Davey and Slaughter (1970), Bartrum, Dobrowolski and Schache (1977), Fiedler and Munro (1984) and Espinosa-Gomez el al (1989).Lead concentrate is smelted in Mount Isa while zinc concentrate and bulk concentrate (locally called Low Grade Middlings or LGM) are railed to Townsville and shipped to custom electrolytic zinc plants and ISP smelters.

Jan 1, 1993

By G. W. Garside

In order to render my descriptions more intelligible, I have compiled a general map of this section of Alaska, showing accurately the relative positions of the most important districts where valuable deposits of minerals have been discovered (page 819). Upon inspection of this map, it will be observed that the chief metalliferous belt in this mineral field is in close proximity to the mainland shore, the trend of which it follows for more than a hundred miles in a northwest and southeast course, while the mineral croppings on the adjoining islands are much shorter in extent, and more irregular with respect to their strike and continuity. This principal metalliferous zone, which I will call the main-land system of lodes, contains gold, silver and lead, besides traces of copper, zinc and iron, gold being found extensively in a free state and also associated with sulphur, and with many of the sulphides of iron, lead and other substances. On the line of this belt, as shown on the map, there are a number of distinct mineral districts. Beginning at the southerly extremity, they are named as follows: Sumdum, Snettishham, Grindstone Creek, Sheep Creek, Gold Creek, Lemon Creek, Montana Creek and Berners Bay districts, each deriving its name from the hay or creek on which it is situated. Harris mining district, as legally organized under the local customs, rules and regulations adopted by the miners of Juneau, embraces, within its exterior boundaries, Grindstone, Sheep, Gold and Lemon Creeks, and all of Douglas Island. The limits of this immense metalliferous horizon are becoming definitely known through the exposures made by prospectors. The belt, as now recognized, varies in width from one to several miles, the lateral measurement being greatest at Juneau in Harris district, where the famous Treadwell mine, with its slate foot-wall, marks the westerly boundary of the zone, while the eastern side of Silver Bow Basin, with a granite hanging-wall, defines its easterly border.

Jan 1, 1893

By M. J. Marcinkowski, R. M. Fisher

The flow stress-grain size relationship has been determined at room temperature in both a disordered and a fully ordered FeCo for plastic strains up to 30 pct. The results are in agreement with a Hall-Petch relation of the type given by Of =a,+kd-1/2 where of is the flour stress and a, increases mono-tonically with increasing strain to a maximum value which is much higher for the ordered than for the disordered alloy. The slope, k, is found to increase FOLLOWING the original work of Halll and petch relating the effect of grain size to the lower yield stress of iron and steel, it has been generally found that the yield stress oy.s. of polycrystalline metals with strain to a maximum and then decrease for both ordered and disordered alloys. However, k for the ordered alloy is in general higher than that for the disordered alloy and the critical strain for k max somewhat larger. All of these observations can be satisfactorily accounted for quantitatively and in some cases semiquantitatively by using a slip band-grain boundary intersection model, and by taking note of the fact that, in general, moss slip, while quite common in the disordered alloy, is extremely difficult in the ordered alloy. obeys a relation of the form oy.s.=a0+kd-1/2 [1] where a, and k are constants and d is the mean grain diameter. For convenience, and in accord with prevailing custom, Eq. [I] will be referred to simply as the Petch relation. Tjerkstra3 and Armstrong, Codd, Douthwaite, and petch4 showed that the flow stress af of iron or steel measured at strains of up to at least 20 pct also obeyed a relationship of the type given by Eq. (11. The latter investigators have also shown that Eq. [I] applies to fcc and hcp metals and alloys.

Jan 1, 1965

By Francis N. Flynn

Many excellent papers, descriptive of the milling and smelting of every kind of commercial ores, the refining of virgin metals, the casting into various shapes demanded by the trade, the rolling into shapes best suited to the factory machinery and the making of composition alloys to suit every requirement have been issued by the many technical societies dealing with non-ferrous metals. It is a wonderful collection of papers, of which the mining and metallurgical engineers may well be proud, but strange as it may seem, metallurgists in general appear to take the stand that when they have delivered suitable alloys to the foundry and rolled products to the factory their duty to write papers has ceased, at least in so far as the A. I. M. E. is concerned. Still we read in the daily papers that the mining companies are absorbing metal-manufacturing industries. The purpose of this paper is to describe the reclaiming of non-ferrous scrap metals at manufacturing plants, taking as an example the automobile industry. Collection and Disposition of Scrap Until about five years ago, much of the factory scrap, with little or no preliminary treatment, was sold to secondary-metal smelters. Of late years the factory salvage department has become an important part, of the plant in reclaiming everything of value and incidentally does much of the work formerly done by the smelters. Like most good things, it is sometimes overdone, and much work is done at the factory with inexperienced men that could be done much better by experienced skilled labor at the custom smelting plants. Employees of the salvage department collect the waste products in all departments at the source and in that way avoid much contamination. Every reasonable precaution is taken to keep the scrap clean. It is hand-sorted, cut, burned, magnetized, concentrated, separated or compressed, as the case may be, preparatory for re-use in the plant or for selling to others.

Jan 1, 1930

By H. A. Wentworth

THE Huff electrostatic plant of the United States Smelting Company operated in conjunction with its wet concentrator at Midvale, Utah, was the second plant of substantial size installed using the Huff process, and the first plant to be put in operation on the so-called Western complex ores. In spite of the machinery being of early design and consequently embracing many of the mechanical weaknesses incident to a pioneer plant the mill has operated steadily and uniformly since the summer of 1909, about five years now, without any material change other than some re-arrangement of the machinery for better handling of the sizes. The ore, at present coming almost entirely. from the company's mines in Bingham, is of practically the same composition as that upon which the plant was first put in operation. The crude ore, consisting of the sulphides of copper, lead, zinc, and iron, and containing small amounts of gold and silver, is brought by train and delivered to the hoppers of the wet concentrator, where by jig and table treatment, there are produced a shipping lead concentrate, a tailing and a middling product, the latter being conveyed in push cars to the adjoining electrostatic mill. The crude ore delivered to the wet concentrator contains from 6 to 9.5 per cent. zinc. At times the plant is used also for the treatment of custom ores from the Bingham district and elsewhere, and at such times the results of the plant vary according to the material in use, but as by far the larger portion of the product is that from the company's own mines, the results given below are fairly indicative of the general work obtained. The accompanying diagram illustrates graphically the flow of the ore through the electrostatic mill. The middling coming from the wet mill containing from 15 to 18 per cent. moisture is hoisted while on the cars by an elevator, and delivered from the top of the elevator to a hopper over the drier. The drier first installed was of too low capacity to take care of the moisture present in the tonnage to which the mill was later

Jan 8, 1914