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By G. A. Smyres

A GaC12--B2 l-eachtng procedure and meEal-recovery method for treating an arsenical Cu-Co sulfide concentrate was developed by the Bureau of Mines as an alternative to smelting, which is no longer considered an environmentally acceptable method for treating arsenic-containing ores. The procedure involved leaching in a CaC12 solution with CaC03 for 96 h at 26 pct solids (concentrate and CaC03), 1150 C, and a pressure of 50 psig (345 kPa) with oxygen. More than 98 pct of the cobalt and 97 pct of the copper were extracted, and 99.98 pct of the arsenic and 99.9 pct of the iron remained in the leached residue. A filtration rate of 2.9 gal/(ft2.h) [118 L/(m2.h)] and a cake formation rate of 36 Ib/(ft2.h) [172 kg/(m2.h)] were obtained by filtering reacted pulp at 1000 C. More than 99 pct of the copper in the pregnant solution was extracted as CuCl2 by golvent extraction with a new copper extractant. Copper was stripped from the loaded organic with a sulfate-chloride solution, which was used as the anolyte for electrowinning of copper in a membrane cell. Copper plate produced was more than 99.99 pct pure and requi.red 0.81 (kW'h)/lb Cu [1.78 (kW·h)/kg Cu]. Cobalt sulfide was precipitated at pH 3 with Ca(HS)2.

Jan 1, 1986

By E. C. H. Becker

When data points, plotted on X-Y coordinates, lie along a simple line, their regression can be matched to a high degree of accuracy by one or other simple algebraic expression (Boot and Cox, 1970). Under these conditions, interpolation is axiomic. Further, if the expression defines no more than a straight line, a parabola or other such line which can be related to some specific mechanism which generates the points, then extrapolation might be valid. However, any extrapolation would depend on the continued, unchanged functioning of the mechanism. Studies of more intricate assemblages of data points have long been based on representation by means of series (Fourier, 1811). If sufficiently complicated, several different algebraic expressions can represent the same intricate regression accurately (Hoerl, 1954). However, without reference to a mechanism, no extrapolation is contemplated. Typically, variations in the prices of minerals with time are. sufficiently complicated to render invalid any simple attempts at extrapolation. The computer, however, can be used to derive algebraic expressions which match complicated regressions and also can be represented by the functioning of a mechanism (Becker, 1984). The techniques involved have been applied with advantage in the study of time series representations of mineral prices.

Jan 1, 1986

By W. C. Baver

Even before the energy crisis developed in the early '70's, considerable research world-wide was being directed towards the development of schemes to both reduce the energy requirements and to reduce air pollution emissions associated with the manufacture of glass. In many cases the sought-for solutions would benefit both objectives. If, for example, the glass batch could be consolidated into such compact forms as briquettes or pellets, they could be preheated in a moving-bed heat exchanger with the high-temperature exhaust gases from the glass furnace. Lower furnace temperatures would thus be possible with a corresponding reduction in heat losses and total fuel consumption. Moreover, the lower temperatures would also reduce the amount of nitrogen oxides generated in the furnace and emitted to the atmosphere. Many tests on consolidated glass batch have been run in many countries. In some cases, extended tests on production furnaces have also been included in the programs. For various reasons, however, none of these has proved to be economically attractive. The current, but temporary lull in the rapidly rising cost of energy which has been with us in recent years, has reduced the push for research for energy saving means for melting glass. A few of the current programs will be discussed. Since raw material requirements, primarily physical in nature, are affected by some of these schemes, these will also be considered.

Jan 1, 1986

By R. A. Hill

A brief explanation of the theoretical functioning of a regenerative system followed by its application to firstly, shuttlecars and then continuous miners and its effect on performance thereof with regard to handling, production and safety.

Jan 1, 1986

By N. Saracoglu, J. P. Golightly, R. H. Wallis, J. J. Brummer

"The McClean uranium deposits are located 11 km west northwest of the Rabbit Lake Mine. Their average grade is 1.8 % U3O8 , and they contain 6. 350 tonnes of uranium oxide in seven pods of variable grade and mineral assemblage. They are hosted by both basal Athabasca Group and the regolith developed on the underlying crystalline basement. The major mineral facies are: sulphide, arsenide, 'bleached', and hematite, with the important uranium minerals being coffinite, uraninite and pitchblende. Abundances of carbon and sulphur isotopes are consistent with their derivation from pyritic graphite in basement gneisses. Isotopes of oxygen and hydrogen suggest equilibration at temperatures of about 200°C. Ar39/ Ar40 age determination of illite associated with ore suggest mineralization began about 1300 m.y. ago and that significant alteration had ceased by about 1170 m.y. ago though Pb/ U data suggest the deposits continued to evolve into the Mesozoic.IntroductionThe McClean deposits lie on the eastern side of the Athabasca Basin of northern Saskatchewan where they are part of a cluster of uranium deposits lying west of Wollaston Lake (Fig. 1). The general stratigraphy is schematically portrayed in Figure 2 which emphasizes that mineralization is hosted by both the Athabasca Group and the underlying regolith and also that the deposits are preserved at depth and have not suffered from preand post-Pleistocene weathering and erosion. This circumstance, combined with their simple shape and the presence of seven separate zones of mineralization (pods) allows a description, based on over 450 fully cored drill holes, to be made of the wide variation in chemistry, grade, alteration patterns and position relative to the sub-Athabasca Group unconformity. Ar39 / Ar40 age determinations have been made of illites associated with regolith, Athabasca Group and mineralization and studies are in progress on C, S, 0 and H isotopes of mineralized material and host rocks. Only some of these data have been published; Brummer et al., (1981); Golightly et al., (1982); Bray et al., (1982); and Saracoglu et al., (1983). The only other published data on McClean geology are by Tremblay (1982, 1983)."

Jan 1, 1986

At the outset I want to thank you for inviting a representative of the Chamber of Mines of South Africa to address you on the subject of mining and its future at this, the 13th Congress of the Council of Mining and Metallurgical Institutions. It is indeed a pleasure and an honour to be here. As many of you will recall, four years ago I, as the then President of the South African Institute of Mining and Metallurgy, had the privilege of hosting and welcoming you to the 12th Congress, the third such congress hosted by South Africa. The late Sir Ernest Oppenheimer, President of the 1930 Congress - the first to be held in South Africa - in his opening address foresaw the mining industry as "the most potent factor in spreading the benefits of civilisation over the sub-continent." We have come a long way since those halcyon days but, as I noted four years ago, it still remains true that mines have been, and will continue to be, the missionaries of development in many, if not most, of the Third World countries. I have been asked to address you on the subject of "mining" and to let my imagination roam widely so that delegates can leave the congress with a broader vision than they brought on arrival. It is a tall order and in my attempt to fulfil it I ask you to cast your minds back 120 years to a sultry, rustic day when the first diamond was discovered in South Africa at the now famous town of Kimberley. At that time the South African economy, predominantly pastoral, was still at subsistence level. Almost overnight the ensuing diamond rush turned the then British- owned northern Cape Colony's semi-desert scene into a hive of mining activity, every prospector bent on making his instant fortune. It was very little different, I am sure, to the gold rushes that hit California in 18+8, Australia in 1851, New Zealand in the 1860s. and the Yukon in the 1890s.

Jan 1, 1986

By A. A. Sobek

Controlled release systems delivering the required concentration of an effective bactericide over an extended time period have been developed by The BFGoodrich Company's ProMac® Systems group. The ProMac system is site-specific and includes a four-step approach to controlling acid mine drainage (AMD): (1) Diagnosing the problem, (2) Prescribing the treatment, (3) Supervising the application of controlled release bactericides, and (4) Honitoring the success of applied treatment. The success of the ProMac system is evidenced by improved water quality, healthy vegetation, a reduction in levels of acidophilic thiobacillus, and a corresponding increase in population of beneficial microorganisms.

Jan 1, 1986

By K. Pagalthivarthi, P. V. Desai

"During solidification of alloys, many inter-related physical processes, such as melt convection, mass diffusion, heat transport, macrosegregation and melt-undercooling occur. Several research workers have studied one or more of these effects separately. To answer important questions on solidification behavior, an overall approach interrelating the processes is necessaryAs a first step toward accomplishing the overall modeling, the freezing of a binary liquid metal is examined. The various stages during freezing of the alloy are critically described to build a continuum model for the entire process. Diffusive mixture theory is used to write the conservation equations for the liquid and the mushy zones. The concept of local thermodynamic equilibrium in the presence of curvature effects is used to restrict the number of degrees of freedom within the mushy zone. Constitutive equations relating flux quantities and affinities, the governing differential equations and boundary conditions are discussed briefly for the freezing process.IntroductionA solidification study encompasses such facets as solifidication time, microstructure, macrosegregation of the solute, shrinkage effects and soundness of the casting. Influence of one or more of the coupled heat and mass transfer phenomena such as local solute redistribution, thermosolutal convection, melt undercooling at dendrite tips and heat dissipation to the ambient have all been previously examined [1-3J. Several studies have examined the individual facets of alloy solidification as isolated processses. In fact, the transport processes occur simultaneously and a comprehensive model should include their inter-relationships. In particular, some of the existing studies of the mushy zone [4-6J do not emphasize thermodynamic completeness. This work represents an attempt to develop a thermodynamically consistent model of the entire solidification process on physical grounds."

Jan 1, 1986

By W. A. Cincilla, S. C. Tadolini

INTRODUCTION Resin bolting systems continue to gain popularity in underground coal mines in the United States, and their general success under a wide range of geological and operational conditions is well documented. In 1984, 36% of all bolts used were resin-grouted systems. However, many questions dealing with basic support mechanisms and the influence of various factors on bolt effectiveness in situ remain only partially answered. The Bureau of Mines' Denver Research Center conducted a major research project to investigate the influence of installation procedures on the effectiveness of resin-grouted roof bolts. The project consisted of two main studies: the first dealing with the contribution of bearing plates to the load-carrying capability of the bolt; the second examining the relationship between installed grout column and the anchorage capacity as measured by the standard pull-out test. Additionally, a finite-element computer model and other analytical and empirical techniques were applied to aid in the basic understanding of the test procedures and to examine the load transfer mechanism in resin-grouted bolts, which to date has not been comprehensively assessed. The plate study includes field test results from two mines (Fig. 1). At these test sites two behavioral parameters were measured: the actual loads that bearing plates were subjected to when installed in conjunction with full-column resin grouted bolts, and the roof movements generated by the applied loads. Results indicate that bearing plates are subjected to varying degrees of loading, which range from conventional installation pressures of 2.2 kN (500 lb), up to a measured load of 142.4 kN (32,000 lb) when the immediate roof is shifting and deforming. These measured loads indicate that the bearing plate is an integral part of the support system. Differential sag stations, installed to monitor roof displacements in the test sites, show the highest degrees of loading occur in conjunction with the largest amounts of movement. The column-length study addresses possible reductions in anchorage capacity of "full column" bolts. These reductions could result from such factors as the loss of grout to surrounding strata, or improper mixing of catalyst and resin. Field test sites were established at eleven mines located in major coal mining districts throughout the United States (Fig. 1). Four major roof-rock types were represented in the study: shale,

Jan 1, 1986

By Tetsuro Ohashi, Tooru Matsumiya, Yoshio Abe

"The three-dimensional deformation of a continuously cast slab was modeled into two-dimensional deformation by developing the solidified shell of the slab. The developed solidified shell was divided into rectangular elements. The thermal strain produced as the slab is wi thdrawn over one roll spacing in the casting direction was calculated from the temperature change during that time and the increment of the geometrical unbending strain during the time was calculated from the change in the radius of curvature of the slab by assuming that the neutral axis of bending is located at the mid-thickness of the slab and that the transverse section of the slab is kept in a plane during unbending. These strains were imparted to each element as initial strains. The interaction between the elements and the overall deformation of the solidified shell were analyzed by the finite element method.The analysis was performed on a slab being cast on a machine of the circular arc type with progressive unbending. The following findings were obtained as a result. The effect of unbending is spread in the upstream and downstream directions of the slab by the shear deformation of the narrow and wide faces. As the shear deformation increases, the strain in the unbending zone decreases and the strain outside of the unbending zone increases. The effects of secondary cooling conditions, slab size, radius of caster circular arc section, compression casting, etc., were also analyzed. IntroductionTo develop a method for preventing the internal cracking of continuously cast slabs, it is important to acurately analyze the deformation of the slab and this subject has been extensively investigated. Many researchers, including the present authors, have analyzed slab bulging. (1)- (11) Analysis has also been made of thermal deformation that assumes importance in continuous casting of small-section blooms.(12)-(18) However, unbending deformation, an extremely important subject for continuous casters of the circular arc type, has not been fully analyzed."

Jan 1, 1986

By B. J. Huls

The commissioning of a Distributed Digital Control. System for the grinding circuit at Cuajone, was completed by mid August, 1985. Development of a successful strategy, excellent operator acceptability and the visual aspects offered by the display of the central console, improved mill throughput significantly. The inherent features of a digital system enhanced the flexibility in grinding control and allowed the mills and classifiers to be operated at maximum capacity. This paper discusses in detail the strategy development, the production restrictions encountered, and evaluates the overall performance of the digital control system. 1.0 Introduction In November 1976, the Cuajone Concentrator, located on the western slope of the Andes in Southern Peru, was commissioned to treat a nominal 41,000 TPD of ore. A systematic elimination of production restrictions has resulted in a continual increase of concentrator throughput to 48,700 TPD before the grinding control was in- stalled.

Jan 1, 1986

By Clark G

The latest addition to the grinding circuit at Bougainville Copper Limited is another 5.5m by 7.3m primary mill (No.13). The mill can operate in a primary or secondary mode. Its distinguishing feature is its capability for speed variation, by means of a cycloconverter-fed synchronous ring motor. The engineering and metallurgical reasons for selecting such a drive system are described together with aspects of the installation and commissioning. Results of investigations into the relationship between mill speed and grinding efficiency are presented. It is concluded that mill speed variation within the range 70 to 80% of critical speed has very little effect on grinding performance. Beyond this range, grinding performance deteriorates. The same conclusions were reached when mill speed was varied at reduced ball charge levels.

Jan 1, 1986

By Andrew E. Grosz

The United States is dependent on foreign imports for about 80 percent of its ilmenite, about 60 percent of its rutile, and virtually all of its monazite. Nearshore marine sand deposits and beach-complex sediments in the southeastern United States are important domestic sources of ilmenite, leucoxene, rutile, zircon, monazite, and a number of other less well known economic heavy-mineral (HM) species. Because global onshore reserves of placer titanium minerals may fall short of demand in as few as 20 years, offshore research in HM placers will become more important. The Atlantic Continental Shelf (ACS) defined by the shoreline and the 200-m isobath varies in width for the modern U.S. coastline from a fraction of a kilometer to about 150 km offshore of Cape Cod, Mass., and includes an area of about 3.91 x 105 km2. It probably contains 3-7 x 1011 m3 of sand and gravel which may locally contain commercially exploitable placer HM deposits.

Jan 1, 1986

Determine the dust reduction capabilities of various bag valves available to the minerals processing industry. The Problem Many different types of ground mineral products are packaged into 50-and 100-lb paper bags. Although bag technology is continually improving, dust contamination from bags still remains a significant problem for workers. The greatest source of dust is the bag filling valve. Ideally, the bag filling valve should close after it fills the bag with the ground mineral product. However, the valve usually fails to close properly since some mineral product gets trapped inside the valve during filling and ejection. As a result, when the bag has been filled and falls from the fill station, a rooster-tail of product is discharged from the bag valve. As the bag hits the conveyor belt, additional product discharges from the bag valve. The dust from these sources contaminates the air inspired by the workers filling the bags as well as the work area. Dust also clings to the outside of the bag, contaminating the pallet loading station. Because the various commercial bag valves are composed of different materials, a dust analysis was performed on five of these valves to determine their dust reduction capabilities. The five valves analyzed were: standard paper, polyethylene, extended polyethylene, double trap, and foam.

Jan 1, 1986

By Sidney A. Hiscock

INTRODUCTION Lead and zinc are today rightly regarded as sister metals. Historically, however, they differ markedly with lead being known and in general use as the metal since 3000 BC in several countries which at that time might have been described as mature economies. Zinc was not isolated and recognised as an industrial metal with distinct and valuable properties until about 1700-1800 AD (although it had, of course, been utilised as a constituent of brass for some 2000 years previously). c were well established as industrial metals by the beginning of the 20th century. The present paper briefly reviews the overall growth in world consumption* and changes in the three main areas which today represent the mature economies or industrialised areas, i. e. ,Europe, the United States and Japan. Trends in overall consumption are determined by the demands for the individual uses for lead and zinc. The changes in patterns of use in the industrialised areas - individually and collectively - and reasons for the changes are also considered. LONG TERM TRENDS - 1900-1984 The World Picture Since the beginning of the 20th century the world consumption of lead (3.9 million tonnes in 1984) has grown almost fourfold and that of zinc (4.7 million tonnes in 1984) is almost eleven times greater than it was in 1900. The long-term trend has been one of continuing expansion for both. metals although the pattern has been severely disturbed at certain periods, for example in the years immediately following the two world wars and at times of marked recessions in industrialised areas. Apart from such major setbacks, new levels of consumption have been established regularly every few years. Recently, however, consumption has not really grown and with only a slow and partial recovery in world industrial activity at present, there is no indication that the peak consumptions of 4.2 million tonnes of lead, set in 1979, and 4.8 million tonnes of zinc (1973) will be exceeded in the near future. The growth in world lead and zinc consumption since 1900 is shown in Figure 1 (which includes changes in copper and aluminium for comparison). Overall growth over the period 1900-1984 has been about two percent a year for lead and about three percent for zinc (annual growth for copper has also been about three percent). Increases in tonnage consumption and growth rates by decade for lead and zinc are summarised in Table I. However, the growth rates by decade sometimes conceal very large individual annual increases and decreases. For example, in 1975 lead consumption fell by 13 percent and zinc consumption by 22 percent compared to 1974. In 1976 consumption of lead and zinc rose by 12 percent and 18 percent respectively. The years when consumption 'landmarks' (ie one, two, three and four million tonnes) were first reached are shown on Table 2. Clearly, the pattern of shorter periods being required to attain each extra million tonnes of consumption was broken in the 1970's. The consumption of zinc overtook that of lead for the first time in 1940, and since 1946 has always been at a higher level. Trends in industrialised areas The two key industrialised areas at the beginning of the 20th century were Europe and the United States which between them accounted for some 95 percent of world lead consumption and 98 percent of zinc consumption. Figures 2 and 3 show the growth in lead and zinc consumption, and Figures 4 and 5 the percentage shares for each area since 1900. Europe has usually been the major user of lead except for some years in the 1920fs, most of the 40's and early 50's when consumption in the United States was larger. In 1900, Europe accounted for about 64 percent of world lead consumption and the United States just over 30 percent. Currently, Europe takes about 40 percent of world consumption and the

Jan 1, 1986

By Dennis A. Hansen

The solubility of anhydrous aluminum chloride in solutions of titanium tetrachloride and vanadium tetrachloride was determined as part of a re-search project-by the Bureau of Mines to make a homogeneous alloy sponge of titanium, vanadium, and aluminum. Solubility curves were established using an autoclave at 75°, 100°, 125°, and 150° C. The solubility of AJC13 in TiC14 is 0.2 wt pct at 75° C; it increases to 18.3 wt pct at 150° C. The data concur with data from earlier researchers of this bi-nary system for 75° to 125° C. For the VC14-AlC13 binary system the solubility of AlC13 is 0.1 wt pct at 75° C, increasing to 1.6 wt pct at 150° C. For the TiC14-AlClrVC14 ternary system the solubility of AlC13 decreases from the values found with a pure TiC14-AlC13 system to the lower values found with a pure VC14-AlC13 system at the respective temperatures.

Jan 1, 1986

By James L. Withiam, P. C. Kelsall

The manuscript of this paper was not available for publication when the Proceedings went to press. Should the authors elect, they may distribute copies at the time of the Symposium.

Jan 1, 1986

By T. T. Lin, N. H. Madsen, K. Groom, B. A. Chin

"The objective of this research is to investigate the feasibility of using infrared sensors to monitor the welding process. Data were gathered using an infrared camera which was trained on the molten metal pool during the welding operation. Several types of process perturbations which result in weld defects were then intentionally induced and the resulting thermal images monitored. Gas tungsten arc using AC and DC currents and gas metal arc welding processes were investigated using steel, aluminum and stainless steel plate materials. The thermal images obtained in the three materials and different welding processes revealed nearly identical patterns for the same induced process perturbation. Based upon these results, infrared thermography is a method which may be very applicable to automation of the welding process.IntroductionAutomatic welding is commonplace in industry today. However, most, if not all, involves preprogramming for performance of a repetitive task. These systems are incapable of correcting for perturbations which arise during the welding process. Control of the welding process requires the identification and monitoring of perturbations in a wide variety of parameters. The varied nature of these parameters and the large number of variables involved have thwarted previous attempts at closed loop control of the welding process. The sensor(s) employed by a control system need to meet rather strenuous requirements. First and foremost of these is that such a sensor must be able to identify and discriminate between perturbations that might affect the quality of the weld, including such geometrical perturbations as a change of direction in the seam between the parts being welded, gaps in the seam or a misalignment of the parts being welded. The sensor should also be able to locate and identify contaminants and impurities in the weld puddle and ahead of it while monitoring the extent of the heat-affected zone and the cooling rate of the metal. The sensor(s) should, additionally, be able to perform these tasks in a time frame that is consistent with automatic control of the welding process. This paper presents results that could aid in the assembly of such a controlled welding system."

Jan 1, 1986

By J. S. Roti

Calcium-based scale precipitation is a common problem in mill reclaim waters. An accumulation of these adherent deposits can result in a rapid reduction in water flow, loss of pump efficiency and eventual interruption in ore production. Heap leach applications can also experience the added problems of plugged sprinkler heads, blinded leach pads and fouled carbon columns when scale control is not maintained. The primary cause of scaling in precious metal recovery is the relative insolubility of calcium carbonate. The presence of the calcium ion and bicarbonate alkalinity is common in almost every water source. If the temperature or pH of the water is allowed to increase, the bicarbonate breaks down to carbonate and combines with calcium by the following reaction: Ca +2 +2HCO3 ? CaCO3 + H2 + CO2

Jan 1, 1986

By K. L. Williams

The Bureau of Mines tested a prototype tapered-element oscillating microbalance (TEOM) dust monitor for measuring respirable coal mine dust. The monitor uses the inertial behavior of a vibrating element to measure the mass of sampled dust. Tests were performed to determine variability, drift, the effect of humidity, placement of collection filter, and element orientation during analysis, and comparability with gravimetric measurements of respirable coal dust. Variability was about 1.6 µg. Over about 26 h at 46 pct relative humidity, drift was very slightly negative. When the relative humidity was increased to 78 pct, all units showed a total positive change less then 40 µg over about 70h. Filter placement variation on the tapered element resulting from in- consistent sizing of the filter mounting bases caused significant error (up to 0.2 mg). In practice, calibration of the system for each new filter will eliminate that error. Orientation of the element during analysis did not introduce significant error, but care is necessary when mounting the canister that houses the element to avoid damping oscillation of the element. Dust tests were performed in an aerosol chamber using coal dust. Measurements made by the TEOM dust monitor agreed to within 10 pct of simultaneous measurements by gravimetric personal samplers.

Jan 1, 1986