Search Documents

By J. S. Tosh

The Federal Bureau of Mines has investigated the equilibrium of the system potassium carbonate (K2C03) potassium bicarbonate (KHCO3) potassium bisulfide (KHS) carbon dioxide (C02) hydrogen sulfide (H2S) water (H20). Partial pressures of hydrogen sulfide, carbon dioxide, and water vapor were measured at 70° to 130° C. over solutions of 20-, 30-, and 40-percent-equivalent potassium carbonate containing from 20 to 3,000 grains of equivalent hydrogen sulfide per gallon of solution. This study was made to obtain equilibrium data for evaluating the feasibility of using solutions of hot potassium carbonate for removing, hydrogen sulfide from gas mixtures. The equilibrium partial pressure of hydrogen sulfide may be correlated with the ratio of the molal concentrations of the solutes (KHC03) (KHS)/ (K2CO3). The relationship is shown graphically for the 30- and 40-percent solutions. Once this ratio is determined, the partial pressure of hydrogen sulfide can be obtained from the curves. The equilibrium data show that effective removal of both carbon dioxide and hydrogen sulfide can be achieved simultaneously with hot solutions of potassium carbonate.

Jan 1, 1960

In looking to the future of mineral processing the focus is typically on improved processing units. Basically it is a search for an elusive wonder machine that could revolutionise the economy of mining: the sorter that strips 50% of the ore with only a few % loss of value; the comminution device that uses 5% of the energy while producing fully liberated particles; or the recovery device capable of producing a 99% recovery at 99% grade. These aspirations are propounded against a reality backdrop of sorters rusting in back yards, mill throughputs below design and varying by 30%, cyclones flaring and cut-sizes fluctuating, mediocre recoveries and soaring processing costs. This disconnect between aspiration and reality appears, to these authors at least, to be a mighty chasm. Moreover, it remains one over which we are expected to magically leap rather than methodically bridge. Indeed one may be forgiven for thinking that should such a wonder machine come along, taking advantage of it would be highly improbable. Questions would inevitably emerge on how to feed the correct material, how to cope with the wide variability of feeds, how to control such advanced equipment and how to handle the new product from such a machine. It is likely these questions might lie unanswered, or more regrettably, unasked. It is generally accepted that as an industry we are exceedingly unlikely to teleport from the current status quo to an entirely new reality in a single flash. It is our thesis that the probability of these magical machines materialising is remote, and even if they miraculously appeared, we simply wouldn?t know what to do with them. Rather, it is our contention, that a step change will only arise through a staircase rather than from a single giant leap. We should focus on building those steps and linking them together into a firm structure ? a workable mineral processing circuit. This paper addresses the alternative of a coherent set of modest but significant improvements, integrated to produce the step change we desire: essentially, a reduction of processing energy to below 40%, which we believe is achievable without recourse to any mystical machines. A key underlying capability to designing these dramatically improved processes, is the weaving of independent process models into a coherent circuit simulation, in order to design the new generation of mineral processing circuits. Keywords: step change, circuit design, circuit simulation, energy reduction

Sep 1, 2012

The Bureau of Mines has long been active in promoting the purchase of coal for Government use under specifications that define the requirements in terms of heating value of the coal, expressed in British thermal units, and the composition as shown by proximate analyses. To these, when required, are added the ash-softening temperature, the free-swelling index, and the Hardgrove grindability index. Under most of these specification contracts, the bidders guarantee the quality of the coal, and that guaranteed by the successful bidder becomes the standard of his contract. The deliveries are sampled in accordance with instructions1 issued by the Bureau of Mines, and the samples are analyzed in the Bureau laboratory to determine whether the coal is of the quality guaranteed by the contractor; if it is not, a price adjustment is made. The Government, with the exception of the Tennessee Valley Authority, purchased approximately 5.5 million tons of coal in fiscal year 1971. In connection with these purchases, the Bureau analyzed 4,366 samples. These are published (table 1) for the use of Government officials and the public. Such analyses of delivered coal and tipple samples (samples collected at mine tipples as coal is being loaded into railroad cars or trucks) provide valuable data for use in evaluating future bids. In addition, the continuous sampling of coal as delivered is a check on the practical results obtained in burning the coal.

Jan 1, 1972

By R. Lasmanis

"Washington State's diverse geological setting is reflected by its several types of porphyry Cu-Mo deposits. All are associated with calc-alkaline intrusions, and they range in age from Jurassic to Miocene.The largest is the Mount Tolman Mo-Cu deposit located in the Omineca Belt. It contains 2.18 billion tonnes of material averaging 0.093% MoS2 and 0.09% Cu. There are intermediate-size Mesozoic deposits in the Intermontane Belt. The Cascade volcanic arc hosts small- to medium-Tertiary deposits. Among these, of particular interest is the Sunrise breccia pipe, which has been explored over a vertical distance of 1000 m. It contains reserves of 64.6 million tonnes averaging 0.319% Cu and 0.071% MoS2 with significant tungsten values. The Glacier Peak deposits have potential resources of 1.7 billion tonnes averaging 0.334% Cu and more than 0.015% MoS2 and also contain tungsten. The Margaret deposit can be classified as a porphyry Cu-Au type; it has reserves of 200 million tonnes averaging 0.434% Cu, 0.0175% MoS2> 0.27 g!t Au and 1.92 g!t Ag. Drill intercepts of the North Fork deposit also show significant gold values.Mineralization and hydrothermal alteration of these deposits are typical of porphyry deposits, although some differences can be noted. The Mount Tolman molybdenum deposit contains topaz alteration zones and is transitional between a plutonic type and a Climax-type molybdenum system. Other deposits, such as the Kelsey, Mazama, North Fork, and Margaret, are low-sulphide systems that contain significant amounts of magnetite."

Jan 1, 1995

By R. W. Dalzell

The performance characteristics, efficiency, and operating pressure of jute line-brattice systems were studied under varying underground conditions; various fabric grades and installation methods were used. The test results indicate that line-brattice system efficiency is dependent upon the method of ventilation the method of installation, porosity of fabric, and size of tight rib area.

Jan 1, 1966

By R. C. Gilmore

Underground longwall coal mining sections may develop explosive mixtures of methane-air in the mined-out gobs. If the panel are operated as bleederless or sealed gobs, progressive sealing along the gate roads as the longwall face retreats limits the flow of fresh air into the gob and thus deprives potentially explosive atmospheres of oxygen. In a project sponsored by the National Institute for Occupational Safety and Health (NIOSH), researchers at the Colorado School of Mines have used computational fluid dynamics (CFD) modelling to simulate the flow of gases in longwall gobs. Modelling indicates that targeted injection of nitrogen through the seals along the gate roads inbye the face can be used to control the size and location of methane and air clouds within the gob and to minimize or eliminate the explosion hazard resulting from the formation of flammable methane-air mixtures in longwall gobs.

Aug 1, 2013

By A Densten, C Gimber

Surface water management and drainage is a key aspect of mine rehabilitation and closure planning. In the authors’ experience, drainage related problems are amongst the most common forms of failure in mined landscapes. The appropriate design of surface water infrastructure is therefore a key focus of practitioners. While there is currently a trend towards distributed drainage networks and avoiding hard engineered structures, in many situations (especially for existing landforms) engineered drainage structures cannot be avoided. CITATION:Gimber, C and Densten, A, 2018. A risk-based approach to drainage design standard selection for mine rehabilitation and relinquishment, in Proceedings Life-of-Mine 2018, pp 116–118 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By E. Fidler

A recent headline in the Wall Street Journal declared, "trendy management schemes very often fail." Many of the management techniques addressed in the accompanying article are associated with quality management including reengineering, benchmarking, total quality management, and employee empowerment. The article made the point that executives, employees, and customers who are involved in such programs rate the effectiveness of these programs very low, and the programs often fail. Yet, we all know of companies that have made significant advances in their operations using these same quality management practices. Why do a few succeed while many fail? History has shown that the companies that successfully carry out quality management programs have two things in common: 1) Strong leadership committed to the success of the program. 2) A comprehensive plan for carrying out and maintaining the program. Stated another way -the reason many companies fail is the lack of committed leaders and inadequate planning. It is ironic that the title of the Wall Street Journal article is "The Best Laid Plans."

Jan 1, 1994

By J. R. Nettle

A method has been developed in the laboratory for successfully electro-refining titanium metal. Refining is accomplished in e fused-salt electrolyte using offgrade metal as the anode and collecting the purified metal at the cathode. The characteristics and requirements of the various alkali chlorides tested as electrolytes are discussed in relation to relative ease of purification and serviceability. The various types of cells designed and tested for electrorefining are illustrated and their method of operation discussed. The individual advantage of each cell and the purpose for which it was designed are reviewed. The magnitude of the cathode current density was found to depend largely upon the quantity of soluble titanium chloride in the electrolyte. The physical condition of the anode also greatly affected the cathode current density.

Jan 1, 1957

By S Hille, J Karageorgos

With the increased variability of todayÆs large-scale mining operations, consistent flotation performance is important to improving and sustaining overall recovery through the circuit. The Newcrest Telfer Mine has implemented advanced process control technology to obtain stable level operation and consistent mass pull in the copper rougher and scavenger flotation circuits. The final result has been an overall reduction in variability, which impacts on both copper and gold recovery. This paper describes the methodology and implementation of the improvements in control at the Newcrest Telfer Mine as being an essential part of the business for minerals processing.

Jan 1, 2007

By E. Nolasco, J. Ouellet, T. Tikka

"Shaft bottom structural systems are used in underground mining to support transfer of personnel, equipment and ore to and from underground to the surface. This paper first summarizes the evolution of design philosophy from a concrete tower supported on a concrete plug to the current structural steel design arrangement with unlined shaft walls, clear shaft bottom area with only a concrete housekeeping pad. Then the paper reviews the design parameters, analysis and design, and construction methodology for this rather unique shaft bottom structural system consisting of three sets of hitch beams, with each having specific functional requirements. INTRODUCTION Shaft bottom structural systems are used throughout the world in underground mining operations to provide a means to support the transfer of personnel, equipment, materials, ore and waste entering and exiting a vertical shaft ready for transport to and from the surface via the hoisting system. The shaft bottom structural system, for the Service Shaft (SS) at the Jansen Mine, is designed to accommodate two skips, a personnel/equipment cage, counterweight, services, loading pocket, rope changing, arrestor system, crash (or catch) beams, access platforms, stairs and rope divider system. Stantec and BHP have engineered a unique structural steel shaft bottom system for hoisting system at a Potash Mine. The shaft bottom structural system connects to a fixed guide and cantilever bunton system, used in the vertical shaft (shaft barrel), above the shaft bottom. The geometry for the shaft bottom structural system, shown in Figure 1 a), features three sets of hitch beams, beams which span across the shaft excavation or barrel. At the top of the structural system are two upper hitch beams. These hitch beams support a 64 metre suspended rectangular braced tower (upper tower), complete with steel guides for the conveyances. The upper tower passes through the main station (potash or mining) level and then connects to the top of the arrestor (lower) tower structure via a sliding vertical connection. The potash level is supported by two hitch beams spanning the shaft and loading pocket excavations. The arrestor tower, a braced compression tower structure, is carried by a third set of hitch beams. Below the third set of hitch beams is a short suspended tower complete with access platforms, stairs and the rope divider system."

Jan 1, 2019

By M. D. Riegel, Brian T. Felber

"Construction of foundation elements in an urban environment is often complicated by multiple constraints such as existing foundations, utility conflicts, maintenance and protection of traffic on high volume roadways, low overhead clearances, and vibration and displacement monitoring to reduce risks of impact to existing facilities. Micropiles are commonly a preferred foundation alternative in an urban setting to mitigate some of these risks. This paper presents examples in which micropiles helped reduce risk in an urban setting on the two subject infrastructure improvement projects. The case studies presented include the Verrazano Narrows Bridge HOV and Bus Ramp Improvements in Brooklyn, NY and the Kosciuszko Bridge Replacement in Queens and Brooklyn, NY. The paper details the micropile design, how risks were mitigated, and the complications to each of these projects associated with the urban setting.INTRODUCTIONThe paper begins with background information about the Verrazano Narrows Bridge HOV and Bus Ramp Improvements Project, followed by background information for the Kosciuszko Bridge Replacement Project. This introductory background information is followed by discussion of the urban site constraints, which controlled the foundation type selection for both projects. In closing, the paper discusses the micropile design process, load testing, and construction.VERRAZANO NARROWS BRIDGE HOV & BUS RAMP IMPROVEMENTS BACKGROUNDProject ScopeThe project consists of two new ramps; one designated for HOV / Bus traffic between Staten Island and the Gowanus Expressway, and one to be utilized for storing the barrier transfer vehicle. Also included is the complete reconstruction of Ramps B and F to accommodate horizontal and vertical alignment clearances from the new ramps, removal of the median of the upper level to add one lane, utilities improvements, stormwater improvements, and miscellaneous structural repairs. The new HOV / Bus Ramp was designed for reversible traffic flow to accommodate the demand of the peak traffic direction by movable barrier.Geotechnical / Foundation Engineering ScopeThe geotechnical work included a desk study review of existing plans, geotechnical reports, and geologic maps. This data was subsequently supplemented with a subsurface exploration program. Once completed, foundation design was performed for 25 proposed bridge substructures. Four existing battered pilesupported foundations and two shallow foundations were evaluated for increased loading. Upon completion of the foundation design, foundation plans, specifications, and an engineer’s estimate were prepared. Foundation installation was observed on a part-time as needed basis."

Jan 1, 2016

By Débora Guimarães da Silva

Este trabalho trata da deposição de um nanofilme de sílica através do processo sol-gel na superfície de um substrato vítreo para sua aplicação em usinas térmicas de energia solar. Os filmes foram confeccionados pelo processo de revestimento por imersão utilizando-se um equipamento dip-coating e passaram por um tratamento térmico à 425°C durante 30 minutos. Na etapa de caracterização foram feitos ensaios de espectroscopia de fluorescência de raios-X, refletância difusa no UV-Vis, microscopia eletrônica de varredura e medidas de molhabilidade. As propriedades mecânicas foram avaliadas por teste de adesão da fita e dureza a lápis. Resultados dos ensaios de espectroscopia de fluorescência de raios-X confirmaram haver a deposição de sílica sobre o substrato. Foi obtida uma refletância difusa de 2,72% para o filme antirreflexivo. Imagens no MEV revelaram uma superfície lisa, uniforme e isenta de trincas. Medidas de molhabilidade mostraram que houve o molhamento dos filmes pela água, caracterizando-os como hidrofílicos. Os filmes apresentaram uma adesão de 4B e dureza de 3H. Os nanofilmes de sílica confeccionados apresentaram propriedades ópticas e mecânicas satisfatórias para a aplicação solar.

Aug 17, 2017

By Michel L. Bilodeau, Brian W. Mackenzie, Dallas W. Davis

"The paper formulates an evaluation procedure for examining the effects of location on the economics of developing mineral deposits. This methodology is applied to assess locational aspects of Nova Scotia's competitive position f or mine development relative to other Canadian regions and provinces. The appraisal concerns two representative mine development opportunities, a medium-size open-pit tungsten deposit, and a small underground gold deposit. The influence of regional economic conditions is initially assessed. Then, the consequences of taxation are isolated. Finally, the combined impact of regional and taxation conditions is examined. SettingThe economic potential of mining may be assessed in a number of ways. One approach, increasingly used for both corporate planning and government policy purposes, is to evaluate the competitive position of an actual or potential mineral producer in the international marketplace relative to other suppliers.Such examinations of competitive position vary from cost league comparisons of breakeven costs for operating mines, through the assessment of medium-term costs associated with developing new mine capacity, to long-term evaluations of the economics of mineral supply from the start of exploration. The complexity of the analysis increase s with the scope and timeframe of interest. Many factors are involved. One component of competitive position is the quality of the mineral resources available. Other key factors include existing technology, wage and salary rates, labour productivity, the cost of capital, infra structure requirements, distances from sources of materials supply an d to mineral markets, management attributes, organizational efficiency, government mineral policies (particularly taxation), and inflation and exchange rates. The paper fits within this competitive position framework.The variable economic conditions which exist within Canada have a direct bearing on the viability of mine development and, thereby, on mineral exploration potential. The paper examines locational aspects of Nova Scotia 's competitive position."

Jan 1, 1986

By H. M. Cooper

Many analysts have had difficulty in obtaining accurate and consistent determinations of the volatile matter in low-temperature coke when the usual standard method for coal was followed. The tendency is toward too-high results, due to mechanical losses which are extremely difficult to avoid or control. With cokes there also may be an error due to excessive oxidation of the fixed carbon. Much of the earlier experimental work on the volatile-matter determination in coal, such as that of Parr, Fieldner and Davis, and others, has been on the effect of time, temperatures, shape and size of crucibles, method of applying heat, and type of furnace, all of which data has evolved the present A.S. T. M. standard method for volatile matter in coal and coke. It is not the purpose of this investigation to deal directly with the above phases of the procedure, but rather to study some of the factors affecting the results in those types of fuel which give erroneous results due to mechanical losses. This mechanical loss is usually designated as "sparking." There are two kinds of sparks or incandescent particles which may appear: particles of soot from partially condensed carbon from the burning gases, and unburned particles of the material itself which escape. The first type does not affect the accuracy of the volatile matter results, and is therefore negligible. The second type, however, causes appreciable loss and results in showing higher volatile percentages than actually exist.

Jan 1, 1932

By A McCallum, J Abols, G Patrick, G Johansen

The authors challenge the traditional thinking that whole ore cyanidation followed by Carbon in Pulp (CIP) or Carbon in Leach (CIL) should be applied as a standard process in the majority of gold processing flow sheets. The concept of whole ore leaching by using cyanide can result in unnecessary environmental and capital risk. Alternative, currently available technologies can be used to provide the desired level of gold recovery at a much lower installed cost and less impact on the environment. Gravity concentration, alone or in conjunction with flotation, can produce a gold bearing concentrate that can then be fed directly to a batch or continuous intensive cyanidation unit. The In-line Leach Reactor (ILR) is an intensive cyanidation unit developed by Gekko Systems of Australia. Advantages of this technology include significantly reduced capital outlays for greenfield plants or plant upgrades and increased investor returns. Reduction of onsite cyanide and carbon inventories improves plant safety, materials handling and site security. By using direct electrowinning to treat the gold bearing solutions produced by the ILR, the need for a conventional carbon stripping circuit is removed. Potential also exists to increase grind size û saving energy, further reducing capital and operating costs and decreasing the environmental impact of a mill. Detoxification of cyanide before the release of solution to the tailings dam can minimise tailings disposal and containment requirements. When used in the right application the proposed process will have little or no impact on gold recovery and may actually increase recovery for complex ores. Areas applicable to this type of treatment include: plants in environmentally sensitive regions, lower tonnage higher grade deposits, coarse gold deposits, and preg robbing ores û some of which may not currently be economically feasible using standard processes and flow sheets. We have provided two examples of such projects, where an alternative to whole ore leach and CIP or CIL has the potential to deliver these benefits.

Jan 1, 2004

By Erik Westman, Benjamin Mirabile

"Ongoing research is being conducted to evaluate secondary support performance in longwall ventilation entries. In a three-entry longwall gateroad, secondary supports are applied in the #2 entry to maintain a functional airway for the entirety of second panel mining. This airway represents a pathway for contaminated mine air to travel from the longwall tailgate to the mine bleeder system. The ground response curve concept may be used as a design basis for selection of appropriate secondary support in these ventilation entries. Two types of secondary supports are monitored for load and convergence in this project. These monitored supports are pumpable crib supports and interlocking wood crib supports. To evaluate the effect of support density, two installation patterns are monitored for each support type. Both a single-row, protected airway pattern and double-row, full entry support pattern are monitored for each support type. Load and displacement data is collected for all support patterns as second panel mining retreats past instrumentation sites. Data is collected for approximately 200-feet inby the second panel face or as long as safely possible. Load and convergence data collected will be used to calibrate numerical models that will simulate ground response curves for the #2 entry inby the second panel face.INTRODUCTIONWhen a bleeder ventilation system is used, the #2 entry of a three-entry longwall gateroad system is designed to function as a pathway for contaminated air from a longwall face to the bleeder system during second panel mining. The #2 entry is subject to substantial ground movement and loading during its function as an air course because it is a single entry between two longwall gobs. Secondary support is regularly applied in this entry to maintain air course functionality during second panel mining.Research on performance and design of secondary supports has been conducted extensively over the last 30 years (Barczak and Gearhart, 1993; Barczak and Gearhart, 1994; Mucho, Barczak, and Dolinar, 1999). This research has focused heavily on the application of secondary support in longwall tailgate, with little research on the application of secondary support in bleeders or other ventilation entries (Mirabile and Westman, 2018). Secondary supports in #2 entry are likely to experience similar loading and ground movement as those applied in the tailgate entry. However, the designed lifespan of the mine entry and the definition of acceptable ground conditions differs from mine entries where more extensive research has been conducted."

Jan 1, 2019

By A. Vahed

The Goro Nickel Project is situated in the Southern Province of New Caledonia. Inco Limited and Goro Nickel S.A. have developed a process that features the use of pyrohydrolysis to produce nickel oxide. The process treats a blend of laterites by Pressure Acid Leaching followed by solvent extraction of nickel and cobalt using Cyanex 301®. Purified nickel chloride solution is converted to high purity NiO product and 6M hydrochloric acid, which is recycled back to the SX circuit. In co-operation with Andritz AG, spray roaster and fluid-bed pyrohydrolysis technologies were examined for this purpose. Tests were conducted at the Andritz AG pilot plant in Vienna, Austria, and at Goro in larger scale installations. The latter served to establish process engineering design parameters for scale-up. Several process variables were investigated in both technologies and the off-gas characteristics were established. Fluid-bed pyrohydrolysis was selected for the Goro commercial plant, primarily because it produced a granular nickel oxide. The main focus of this paper is to outline the results obtained in pilot plant studies of liquid fueled fluid bed pyrohydrolysis for the Goro Project. Keywords: lnco Goro Nickel, Fluid Bed Pyrohydrolysis, Pilot Plant Tests

Jan 1, 2004

By Yong Kuk Park

The horizontal cold chamber die casting process can produce a wide range of near-net shape, non-ferrous castings with small dimensional variation, excellent surface finish and very complex geometries. However, top quality die castings can be achieved only when optimal performance of the cold chamber and plunger is maintained during the molten metal injection phase of the process. Cold chambers (shot sleeves) are known to deteriorate fast and sometimes fail catastrophically because of poor design. Catastrophic fracture and wear due to deformation are leading causes to degrade quality, increase downtime and thereby decrease productivity and profitability. Therefore, a systematic approach to minimize irregular and adverse conditions which prevent an intended injection profile, is highly desirable. To eliminate them, design criteria for shot sleeves were developed using analytical tools and available experimental data. The correlation between design and mechanical failures of shot sleeves was shown by the data obtained from the die casting industry. Also, the relationship between die casting process parameters and deterioration/ failure mechanisms were carefully evaluated.

Jan 1, 1996

By J. W. Byrkit

Design features and operating methods at the new Ajo smelter are described in detail. Successful operation of a novel method of handling and charging wet concentrates to a deep bath type reverberatory furnace contribute to the daily production of 200 tons of anodes with good results from the standpoint of both metallurgy and economy. THE New Cornelia Branch of the Phelps Dodge Corp. is located at Ajo, Ariz. Large scale mining operations were started at Ajo in 1917, when a 5000 ton leaching plant was put in service to treat the copper carbonate ore that overlaid the sulphide ore-body. In 1924 a 5000 ton flotation plant was built to treat the sulphide ore and the leaching operation was abandoned a few years later. Changes in practice and additions to plant facilities have resulted in a gradual increase in the milling rate which now approaches 30,000 tons daily. Prior to the erection of the Ajo smelter, flotation concentrate was shipped by rail to Douglas, Ariz, where it was treated in the Phelps Dodge smelter. Construction of a one reverberatory furnace smelter to produce an average of about 200 tons per day of copper anodes at Ajo was started early in 1949. Initial heating of the reverberatory furnace was begun on June 21, 1950. Charging the furnace was started on july 8, and the first anodes were cast on July 14. Neither the anode furnace nor the reverberatory furnace has cooled since the initial firing. Fig. 1 is a photograph of the new smelter. Built primarily to eliminate the '300 mile haul of concentrate to the Douglas plant, the new smelter was designed to treat the Ajo concentrate, with a minimum of capital investment. A novel, and relatively simple, method of concentrate handling and furnace charging made unnecessary the installation and operation of expensive storage facilities and reclaiming equipment, and obviated the necessity of holding in storage large quantities of copper-bearing materials. (Patents are pending in the United States and abroad on the Ajo process.) In the selection and arrangement of equipment, consideration was given to the full utilization of all smelting facilities, reducing the amount of idle equipment to a minimum. The layout of the smelter is shown in Fig. 2. The important problem of internal transportation was minimized by arranging the reverberatory furnace, converters, and anode furnace in a compact group and providing storage bins inside the smelter building, within reach of overhead cranes, for fluxing materials and other supplies needed in the daily operation. This can be seen in the sectional view of the smelter given in Fig. 3. Incorporated in the design were many innovations in smelting equipment intended to facilitate operations and effect economies in maintenance expense and manpower requirements. Table I gives operating data of the entire plant. Metallurgy The metallurgical practice at Ajo is based essentially upon the use of a single, deep bath reverberatory furnace for smelting wet concentrate, without concentrate storage facilities. The large reservoir of slag and matte maintained in the furnace serves to equalize, to some extent, the day to day variations in the nature and grade of concentrate and permits

Jan 1, 1954