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Council for 1998/99 President R.P. Mohring President Elect J.R. Dixon Vice Presidents Senior junior M.H. Rogers Dr L.A. Cramer Immediate Past President Honorary Treasurer Dr N.A. Barcza J.A. Cruise

Jan 1, 1985

By Zamora C

The performance of a system for detecting the onset of overloads on rod mills is described. The system has bee,, tested at CODELCO E1 Salvador Concentrator where, due t,, variations on size distribution of the copper ore feed, th' rod mill is frequently subject to overloads. The main inpur signal to the system is the rod mill sound, after being measured and analog conditioned. This signal and othe signals measuring the fresh ore feed and the mill watt addition are fed to a computer containing a simpl mathematical model. The model parameters are empiricall estimated and an analog output signal is generated, whic gives an early prediction of the overload condition. The experimental results described in this paper show that the overload condition may be predicted with an anticipation of about three minutes.

Jan 1, 1985

By D. Robert Weir

The pioneers in pressure hydrometallurgy have provided a solid foundation during the past four decades. The pressure techniques are now capable of being used to push back the frontiers in the winning of metals. Pressure hydrometallurgy has been used to meet the objectives of extracting metals; purifying metal solutions, recovering metals; and rendering waste streams acceptable for disposal to waste repositories and the environment. Some examples of each of these functions are briefly reviewed. The applicability of pressure techniques to the recovery of precious metals is discussed.

Jan 1, 1985

By P. K. Currie, J. V. Walters

Solution mining of magnesium salts (Carnallite and Bischofite) is taking place near Veendam, in the northeast Netherlands. The magnesium salts are used for the production of magnesia sinter, used as a base material for the manufacture of refractory bricks for furnaces. This paper gives, first, an introduction to the operational procedure followed in Veendam, with the emphasis on some of the unique aspects, and then discusses rock-mechanical aspects of the cavity behaviour. The creep behaviour of magnesium salts is described, and Finite Element calculations on cavity stability and potential surface subsidence are discussed.

Jan 1, 1985

By Ted J. Smith, Stephen E. Kesler

"Zonation patterns are welt developed in the mafic metavolcanic rocks that host epigenetic quartz-carbonate-gold vein mineralization at the Hollinger-McIntyre deposit. Carbonate alteration assemblages are strongly zoned about mineralization. Proceeding inward from background greenschist facies rocks to alteration envelopes enclosing individual veins, the following assemblages are observed:Assemblage I-quartz-albite-chlorite-epidote-actinolite-(calcite)Assemblage II-quartz-albite-chlorite-calcite-epidoteAssemblage III-quartz-ankerite-sericite-(chlorite-calcite)Assemblage IV-quartz-albite-ankerite-sericiteLithogeochemical zoning is equally well developed as variations in whole-rock abundances ofAs, Au, Ba, Rb, and Sb. As and Ba form the most useful zonation patterns, outlining individual ore zones as well as broader trends of mineralization.Gas chromatographic analyses of fluid inclusions in the quartz-carbonate veins indicate that the mineralizing fluid was an H20-C02 mixture. Locally, CH4-rich fluid inclusions are associated with graphitic and/or carbonaceous wallrocks. Fluid inclusions in ore-bearing veins have higher CO2 contents than those in non-ore veins. Extensive sampling and analyses of veins from the area surrounding the deposit reveals a well developed zonation of CO2 contents about the main zone of mineralization. Low CO2 levels (1-2 mole%) in veins are peripheral to the deposit and increase to over 12 mole% in mineralized zones.The observed zoning of the carbonate alteration assemblages is a result of the addition of CO2 to the wallrock, which is consistent with the zoning of CO2 in the fluid inclusions.The zoning patterns delineated in this study are useful in exploration both on a deposit scale and on the scale of individual ore zones."

Jan 1, 1985

By W. K. Summers

During the past few years monitoring systems have been installed to measure the effects of environmental changes on the ground-water resource. The design of a monitoring system depends upon the designer's perception of how the environmental factors merge with his perception of the ground-water flow system. The validity and representativeness of measurements made during a monitoring program depend upon the validicy of the designer's perceptions and concepts. To optimize the design of a ground- water monitoring program the designer should make preliminary measurements to confirm his assumptions.

Jan 1, 1985

By V. Svalbonas

With the occurrences of serious mill structural failures on both ball and primary mills, the mining industry has entered the era of detailed fabrication specifications. Such specifications, however, have been developed as individual entities, often by people not related to the mill design function. Therefore, there has been no effort to relate mill failure or safety to the existence or elimination of specific fabrication flaws; that is, no cause-effect failure relationships have been developed. The omission of this step produces a specification which can be termed uneconomical at best. The present paper attempts to fill this void, by reviewing methods for design consideration of flawed structures, and describing experimental tests used to tie such data to a meaningful quality assurance program in fabrication.

Jan 1, 1985

By Frank F. Aplan

Introduction Gravity concentration may be defined as that process where particles of mixed sizes, shapes, and specific gravities are separated from each other by the force of gravity or by centrifugal force. The nature of the process is such that size and shape classification are an inherent part of the process in addition to separation on the basis of specific gravity from whence the process got its name. Mother nature has long practiced this form of mineral concentration by concentrating such heavy and relatively indestructible minerals as gold, platinum, cassiterite, ilmenite, zircon, and diamonds in placer or beach sand deposits. Once freed of their host granitic or other rock through natural weathering processes, these minerals are then subjected to stream or wave action producing a natural classification and concentration of the heavy minerals. Gravity concentration dates back to antiquity and was certainly the first ore concentration process used when selective mining and hand sorting would no longer suffice to produce the quality of concentrate desired. Forerunners of the present day sluice box and panning techniques were undoubtedly used by the ancient Egyptians on the upper Nile to separate gold from stream gravel. By the second century BC the extraction of gold from veins in quartz was well detailed by Agatharchides, but there is evidence that gold was brought into Egypt from the south as early as the XI1 Dynasty (~1900 BC).1 Most assuredly gravity concentration devices were used during the later Bronze Age to separate the heavier tin and copper minerals from their lighter gangue minerals. The Athenians used an elementary form of Rowing film concentration at their lead-silver mines at Laurium,2 and elementary jigging using wicker baskets was also probably developed at this time. Agricola's famous treatise De Re Metallica3 demonstrates that by the 16th century gravity concentration technology was well advanced and a large number of devices had been developed. Chinese

Jan 1, 1985

By Pamela Binstead

The Institute's ninetieth anniversary was celebrated in grand style with a banquet and dance in the ballroom of the Carlton Hotel in Johannesburg, on 22nd March. Some six hundred and thirty members and guests filled the room to capacity, and many remained to enjoy the festivities until well past midnight.

Jan 1, 1985

By Raymond E. Funderburk

Today, there are four alternatives available for disposal of highly toxic, non-radioactive hazardous waste: deep well injection, chemical processing, landfill and incineration. However, based upon research conducted by the author, a fifth alternative now exists. Disposal in salt. Salt, because of its chemical characteristics, is an ideal medium for retention of inorganic hazardous waste. Except for a few elemental compounds such as lithium and potassium, there is no reaction with sodium chloride. In the family of inorganic wastes, there are basically seven suites of waste that may be mixed together without any chemical reaction. The process developed by the author would be to take a suite of waste, either dewater or add moisture, add a solidification agent to the mix and slurry pipeline the mass into a cavern. Residence time before hardening can be adjusted, but the nominal time until full solidification is 48 hours. Once solidified, the mass will reach compressive strengths exceeding 3000 psi. The slurry can be introduced into an evacuated cavern pumped free of brine, or it can be placed beneath the brine and the waste will force the brine to the surface. The latter technique requires a high degree of engineering control to prevent contamination of the brine leaving the cavern-thus creating more hazardous waste and additional problems. The Environmental Protection Agency endorses the concept both at the research level and within EPA Headquarters. The technology will soon be utilized in a salt formation in Texas.

Jan 1, 1985

By Richard H. Kennedy, G. A. Swanquist, John W. King, Frank F. McGinley, Dale C. Mathews, Hans H. Adler, E. C. Peterson, Ralph M. Wilde

INTRODUCTION From the first historical records of the discovery of uranium as an element and the attempted classification of its minerals in the early 18th century-through its first uses in pigmentation and the coloring of glasses and ceramic glazes-until 1939 when it was discovered that the isotope U235, was fissionable, uranium oxide in the form of pitchblende ores and concentrates (produced mainly in Bohemia, Canada, and the former Belgian Congo) in recent times was the source of uranium compounds incidental as byproducts to the recovery of radium from this invariable associated source. In 1938 this byproduct production from pitchblende concentrates was about 471 st of U3O8, with over 90% from Canada and the Belgian Congo and only 25.85 st from carnotite ores in the United States.1 Under the impetus of the Atomic Energy Commission's (AEC now part of the Energy Research Development Administration) domestic and foreign production incentives and buying programs, and as an initial assurance of atomic armament capability of the United States and the Free World, the growth of the uranium mining and milling industry burgeoned from 1952 to 1962. After a short period of decline, in the second decade and in large commitments beyond, it has again extended its capacity to meet ever-increasing fuel demands of atomic power generation by the electric utilities industry. In 1961 the peak production in the United States alone was 17,758 st of U3O8. Peak aggregate domestic and foreign deliveries of 34,581 st of U3O8 to the AEC occurred in 1960.z Canada's maximum delivery of 13,506 st of U308 was made in 1959. These peak and continued productions in the Free World are largely from: the Mesozoic (Jurassic) and Tertiary (Eocene) sandstones in the United States; the quartz pebble conglomerates of Canada and the Witwatersrand; pegmatites, Jurassic limestones, and Precambrian complexes, with less but significant production; the phosphoria, where byproduct production is minor. This uranium production in the form of precipitated concentrates has come from the milling of ores from these sources, both directly and by retreatment of gold cyanidation tailings on the Witwatersrand. Milling of crude ore has followed these processes: conventional crushing and size preparation, ore drying when required, salt roasting for high vanadium ores and byproduct vanadium recovery, carbonate or acid-leaching processes, classification sand-dine separations or countercurrent decantation (CCD) circuits and complete liquid-solids separations, resin-in-pulp (RIP) or liquid-liquid (solvent) ion-ex- change extractions, clarification of pregnant liquors, precipitation, filtration and washing, sodium and vanadium removals, and drying or roasting and packaging of the high-grade, high-purity uranium concentrate commonly referred to as "yellowcake." Coupled with the hazards and control of dust generation incident to conventional crushing and milling operations, more stringent control of airborne respirable and ingestible radioactive particulates and the protection of personnel against definitive external radiation are inherent to uranium milling. Impoundment and control of tailings and other effluents of uranium milling are more restrictive than in conventional practice, be- cause long-term disposal and containment of the uranium series of radionuclides, whether in solution or in solid form, are requisite to uranium milling and are made manadatory under regulatory agencies of government. 2. GEOLOGY AND MINERALOGY OF URANIUM Early Uses and Byproduct Production of Uranium Uranium was discovered by Klaproth in 1789 but had little commercial importance until the discovery of uranium fission by Hahn and Strassman at the close of 1938. The well-known uranium ores of Joachimsthal, Czechoslovakia, the Congo, and the Colorado Plateau were early sources of radium. Minor quantities of uranium were used for small-scale technical and industrial applications, particularly in coloring glass and ceramics, but most of the uranium was discarded. The Colorado ores were also mined later, chiefly for vanadium. Impetus of Armament Capability and Fuel Demands for Atomic Power Following the discovery of atomic fission, uranium became critically important for military applications and, more recently, as a nuclear fuel. Prior to 1966 uranium was acquired in the United States almost solely for use in the weapons program of the AEC. By 1970 the AEC had procured approximately 325,000 st of U3O8 from domestic and foreign sources. Current and future marketability is primarily dependent upon commercial demand for reactor fuel. Estimates of

Jan 1, 1985

By C. Richard Tinsley

INTRODUCTION Documentary complications arise from the risk apportionment in project financing which generally means that once the project is up and running and has satisfied the lender's completion test, the loan agreement specifically limits the lender's recourse to the project and its assets. It is the purpose of this paper to describe the special considerations which apply to industrial minerals projects and explore the reasons why so few project financings are negotiated in this industry. SIZE Small projects do not warrant the relatively high costs of negotiating and documenting project financing. The extent of the documentation is directly proportionate to either (a) the degree of risk apportionment, or (b) the amount of control given to lawyers to negotiate the documents. Although one would like to believe that project-finance documentation could be off-the-shelf, it is almost always necessary to tailor the documents to the mine development itself and the individual desires of the borrower. Accordingly, the documentation costs and initial expenses are seldom less than $40,000, and for complex projects can reach $400,000. In addition, banks often charge an up-front fee to partly compensate them for their staff time and partly to increase their yield on what is deemed to be a "riskier" loan asset. Another factor is the generally lower debt:equity ratio when bankers are uncertain of the accuracy of the cash flow projections. The ratio of the amount of cash flow left over after debt service to debt service itself is a key tool for project finance (debt service coverage). Bankers will require a higher coverage ratio for industrial minerals projects because of the relatively higher uncertainties in the following categories: Prices Markets Geology/Quality Transportation Environmental This, in turn, means that lower debt:equity ratios are the norm for new industrial minerals projects. INDUSTRY STRUCTURE It is hardly worthwhile to generalise about a field as diverse as industrial minerals, but there are four other structural reasons why project financing has not been widely applied. 1. The most obvious example is the predominance of small-sized operations, largely a function of transportation economics. Geological conditions also contribute to their dispersion. 2. Often, the product is only a small part of a company's business in contrast to many petroleum, metals, or coal companies whose sole business is the production of the raw material. The construction industry is a good example here for cement, gypsum, crushed stone, sand and gravel, and the drilling-mud services business for barite and bentonite. A company is unlikely to jeopardise its main business through the failure of a project financing on one of its key inputs. The corrollary is that the mined input is often regarded as a cost centre and not run on the sort of economic basis suitable for project financing. 3. There may be a reluctance to reveal key aspects of an industrial minerals venture to an outsider for purely competitive reasons. Unlike the other minerals industries which readily share technical information at plant visits and

Jan 1, 1985

By Kim B. Shedd

The Bureau of Mines measured fiber dimensions on crocidolites (riebeckite-asbestos and magnesioriebeckite-asbestos) from the world's four crocidolite mining regions. The objective of the study was to determine whether there are measurable morphological differences between crocidolite fibers that correlate with the high reported incidence of mesothelioma in miners and mill employees in the Cape Province of South Africa and Western Australia, as compared with little or no reported incidence of this cancer in the Transvaal Province of South Africa or Bolivia. Fiber dimensions measured with the scanning transmission elec-tron microscope showed that crocidolites from Western Australia and the Cape Province have more thin fibers than crocidolites from Bolivia and the Transvaal Province.

Jan 1, 1985

The origins of instrument application in the Mineral Industry are discussed. Development of measurement techniques pertinent to the industry is described as is the early application of mini-computers. The current application of microprocessor based equipment and the benefits obtained from this range of equipment are discussed. A speculative opinion as to what future instrument development may offer the industry is outlined.

Jan 1, 1985

By W. D. Riley

The Bureau of Mines is conducting research on methods for the rapid identification and sorting of mixed scrap metals and alloys so that domestic scrap resources can be fully utilized. One method, spark testing, is the examination of the pattern of sparks that results when a metal or alloy is ground on an abrasive wheel. This technique requires experienced sorters. Bureau researchers have shown that spectrophotometric methods can be used in lieu of the highly skilled sorter. The spectra of a mild steel, an HSLA steel, several stainless steels, and four nickel-base alloys have been measured. Differences in the spectra that are sufficient for identification are apparent.

Jan 1, 1985

By W. H. Pomroy

Spontaneous combustion fires in deep metal mines, through relatively infrequent, are nonetheless cause for considerable concern because they pose a direct threat to the safety of miners and are quite disruptive to mine operations. They often occur in remote, inactive, or abandoned sectors of a mine where access for firefighting is difficult or impossible. Over half of all noncoal mine fires that last more than 24 hours are caused by spontaneous combustion. The most common means of fire control for spontaneous combustion fires is sealing and/or Flooding the affected zone. This process is never easy, but it is made especially difficult (and hazardous) if the fire grows in size and intensity to the point where underground fire- fighting crews must wear self-contained breathing apparatus owing to mine air contamination. The Bureau of Mines has developed and in-mine tested a mineworthy fire detection system capable of sensing the earliest traces of spontaneous combustion, thus enabling mine personnel to initiate fire control operations before hazardous atmospheres are created. This paper discusses system design within the context of the harsh mine environment, and describes laboratory and in-mine performance tests of prototype equipment.

Jan 1, 1985

By M. W. Springett

During the 1970's geostatisticians were often accused of not paying sufficient attention to geologic features in the computerised generation of ore reserves. Unfortunately this charge was all -too-often justified and the results of such studies tended to be oversimplified and failed to reveal the full potential of computerised reserve estimation and geostatistical methods. There were some notable exceptions to this trend. Techniques were described that paid a great deal of respect to the geologic characteristics peculiar to certain deposits (Rendu J-M, 1984, Barnes T. E., 1982). At Gold Fields several techniques have been developed for handling the geologic characteristics of ore bodies for reserve estimation purposes. These have developed over time and the evolution of their adoption has been a reflection of our own learning experience from the practical application of computerised reserve estimation on many precious metal s deposits. Problems Typical problems that have been experienced by ourselves and which we have learned to guard against and watch for are: ? "smearing" at geologic contacts ? confusion caused by disparate "selective mining unit sizes" and block sizes ? conflicting estimates generated by field staff using various versions of the polygonal method ? problems in generating meaningful variograms

Jan 1, 1985

By Madgwick J. C

Four manganese dioxide leaching microorganisms, an Achromobacter spp, Aspergillus niger, Elllerobacter cloacae and Elllerobacter agglomerails were purified from sucrose enriched crude mixed cultures which contained at least sixteen, non-leaching, morphologically different, colony types. Fastest leaching rates were obtained from the original enrichment's mixed cultures (1.26 g Mn++ I/d) while best yields of Mn++ m terms of sugar use came from Achromobacter and A. niger being 0.84 and 0.89 g Mn++/g sucrose respectively. The peak efficiency in manganese reduced, per carbohydrate used, coincided with the exponential growth phase for Achromobacter. The two Elllerobacter species performed better in stationary or senescent growth phases.

Jan 1, 1985

By Charles Sabine

The 27,960-acre Newberry Mountains Wilderness Study Area (WSA) is located in the Mojave Desert, 17 miles east-southeast of Barstow. In 1983, the U.S. Bureau of Mines, in conjunction with the U.S. Geological Survey, investigated mineral resources of the area as part of the wilderness review process. The Newberry Mountains are underlain by Paleozoic metamorphic rocks, Mesozoic plutonic rocks, and Tertiary volcanic rocks. Eleven mines and prospects were examined. Of the seven sites within the WSA, only the Northrup Prospect is mineralized. Only a few tons of manganese-bearing rock, containing 49% manganese oxide (MnO), are exposed, but exploration may disclose larger deposits. The Azucar Mine, a past producer of gold, is the only site examined outside the area that appears mineralized. Sample data from quartz veins exposed at the surface do not indicate that resources are present; however, the occurrence could not be fully evaluated because underground workings were not accessible. Sand, gravel, and stone are plentiful in the WSA, but alternate sources outside the WSA are available.

Jan 1, 1985

By T. F. Anstett

The Bureau of Mines evaluated the potential availability of chrysotile, amosite, and crocidolite asbestos from 42 properties in market economy countries. This resulted in the development of tonnage-cost relationships indicating the quantity of grades 3 through 7 asbestos at various average total costs of production at 0% and 15% rates of return on invested capital. The availability of grades 2 and 8 was also evaluated, but since each is produced at only one property, no analytical results were given. Total demonstrated recoverable chrysotile fiber potentially available of grades 3 through 7 from the 42 properties evaluated follow: 1.59 million t, 21.00 million t, 16.74 million t, 15.54 million t, and 19.27 million t, respectively. The total amount of crocidolite is 1.69 million t. Owing to the good potential for discovery and development of new deposits, long- term availability of fiber of all three types is not in jeopardy. However, many of the crocidolite properties evaluated in the northern Cape crocidolite field of South Africa have relatively small demonstrated resources, and new deposits will have to be exploited by the late 1990's to sustain projected levels of production.

Jan 1, 1985