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By G. Thorsen

An alternative way to the normal practice of precipitation of jarosite, goethite, or hematite for removal of iron from zinc sulphate process liquors/ is to employ the techniques of solvent extraction. The process presented avoids the addition of any external alkali for the extraction of iron by integrating the leaching and solvent extraction steps in a hydrometallurgical zinc plant. By starting the leaching of zinc from the solid zinc calcine material with an organic solution of an acid liquid cation exchanger, the organic phase is loaded with the organic zinc salt from the direct reaction with zinc oxide. The residue from the organic leaching is transferred to a hot acid leach circuit where the remaining zinc oxide and the zinc ferrites will dissolve form¬ing an aqueous sulphate solution of zinc and iron. In the subsequent solvent extraction of iron from this aqueous leach solution, iron is exchanged with zinc from the organic phase. The commercial carboxylic acid Versatic 10 (Shell) is highly efficient for this integrated process of leaching and solvent extraction. The resulting iron-loaded organic phase is heated to 150-200 C in the presence of water whereby the iron will be directly precipitated from the organic phase as iron oxide of high purity and the regenerated organic acid is recycled to the organic leaching step for reloading with zinc.

Jan 1, 1980

By V. E. Suter

Anyone with geothermal experience can readily attest that geothermal operations are a natural extension of oil and gas operations. A geothermal company and an oil company need the same type of people to do the same kind of work. In the geothermal industry, geologists and geophysicists define prospects through surface geology, analysis of surface seeps, magnetics, gravity, and resistivity surveys - techniques similar to those used in the petroleum industry. In addition, shallow (250-ft) temperature gradient holes often are used in geothermal operations. Landmen take geothermal leases that are patterned after oil and gas leases. Exploratory drilling is done with the same drilling contractors and same drilling rigs, with minor modification. Drilling foremen and drilling engineers share the same objective of making the most hole, in the shortest time, at the least cost, with a proper completion. Petroleum engineers test the wells, design the completions, determine the reserves, make economic calculations, work with the tax assessor, and manage the reservoirs. Production engineers build roads, locations and pipelines, install gas/liquid separators and meters, and operate production and injection facilities. A contract to sell steam to a public utility is required. Various governmental regulations, permits, environmental concerns, and public affairs pose similar problems in both industries. Also required of both are top management people who are acquainted with geologic risk, prepared to accept million dollar dry holes, willing to bid competitively at lease sales, and able to invest large sums based on a technology not yet fully proven. Successful geothermal development requires in-depth financial ability similar to that required for petroleum development. A high capital investment is required early for leases, geological and geophysical work, and exploratory and confirmation drilling. After

Jan 1, 1980

By Rodolfo V. de la Cruz

Abstract. The Hoskold mineral valuation method was critically examined. The original derivation was presented and found to contain a number cf erroneous assumptions as follows: the sinking fund must be available for reinvestment in another property; the series of reinvestment of the sinking fund results in a perpetual annuity to the investor, and; evaluation of the present value of the net cash flows at the speculative rate of interest. The proper procedure of deriving the Hoskhold mineral valuation formula was discussed and illustrated with a cumulative cash position diagram, a useful tool in economic evaluation and investment decision methods.

Jan 1, 1980

By J. B. Goddard

Abstract. Leaching of, uranium in situ from sandstone deposits with ammonium carbonate solution containing: dissolved oxygen occurs rapidly compared with the leaching of the bulk of the sulfur present as FeS2. However because of their high reducing, capacity and their relative abundance, the FeS2 minerals consume; the bulk of the oxidants A pressure leach apparatus was-construtted which permitted the measurement of oxygen consumtion by FeS2. Oxygen consumption by FeS2 is best described by a first-order reaction. The experimental rate constants for various cores are roughly proportional to their FeS2 contents.

Jan 1, 1980

By Haydn H. Murray

The area from Ohio on the east, Tennessee on the south, and Minnesota on the west: contains some very unique and useful clay deposits. Included are fireclays and plastic clays in Ohio, Kentucky, Indiana, Illinois, and Missouri; flint clays in Kentucky and Missouri; ball clays in Kentuckv and Tennessee; adsorbent clays (fuller's earth) in Missouri, southern Illinois, and Tennessee; and alluvial clays and shales for structural clay products from every state. Unique kaolin clays are known in Minnesota, Missouri, and southern Illinois and halloy-site localities are known in southern Indiana. The geology, physical properties, and uses or potential uses of these midwestern clays are described.

Jan 1, 1980

By J. Slivnik, A. Stergarsek

[The site] [Z]irovski vrh uranium ore deposit is located in the extreme north-western part of Yugoslavia, some fourthy kilometers from the capital of Socialist Republic of Slovenia, Ljubljana, not far from the Italian and Austrian border. The sandstone type deposit of uranium ore with medium grade is located in a foothill of Julian Alps. The site shows some typical conditions for this region, which demand special attention in respect to the incorporation of an uranium treatment facility into environment. Among these specific conditions the following site characteristics should be mentioned: - populated area of agricultural and recreational value, - unconvenient climatic conditions with excessive rainfall and long lasting temperature inversions in the winter time, - very pure surface and underground waters which supply the drinking water reservate for large area including the capital of Slovenia, - sharp relief, - unconvenient geological structure. The choise of technology The intention to produce uranium and at the same time respecting the natural characteristics and existing uses of the site made the design of the ore treatment facility relatively difficult one. In general, there were two basic alternatives available perform the task. First alternative was to adopt the usual technological flowsheet with wet tailings disposal and with discharge of used water i.e. liquid effluents into the river. In order to prevent the negative impact of such technology on the sourrounding area sophisticated water purification installation and costly measures in wet tailings disposal e.g. impermeabilisation of large areas by concrete injections, large dam constructions, uncertain capturing of the water sources should be employed. Second alternative was to modify the usual flowsheet by employing the maximal recycling of liquid effluents to the process and to dispose the solid

Jan 1, 1980

By Robert H. Poppe

The Regional Copper-Nickel Study examined the potential impacts of copper-nickel sulfide mining, concentrating and smelting operations in northeastern Minnesota and gathered extensive monitoring data on the ecological characteristics of the region's aquatic and terrestrial biota. Because of the many development options possible, the diversity of the region's ecology, and the uncertainty of future environmental regulatory requirements, the Study did not attempt to measure the magnitude of environmental impacts on specific biological communities from a specific development proposal. The Study provides a broad base of environmental resource and impact information that hopefully will assist mining developers and environmental regulators when assessing specific proposals in the future. The following discussion is not a description of what will happen if copper-nickel development occurs in northeastern Minnesota but an exploration of why certain potential aspects of such development should be carefully considered and adequately understood before unnecessary or irreversible decisions are made.

Jan 1, 1980

By C. E. Jordan

Abstract. The U.S. Department of the Interior, Bureau of Mines, as part of its effort to maintain an adequate supply of minerals and metals to meet national economic and strategic needs, is conducting research on the pneumatic recovery of coarse mica. A system of crushers, screens, and zigzag air classifiers is used to concentrate coarse liberated mica particles from mica ore and from the waste tailings of abandoned mica operations. The plus 0.21-millimeter-size mica is effectively recovered by this method. The mica concentrates produced contain over 90 percent mica. The method recovered up to 78 percent of the mica in the samples. As a dry concentration method, the pneumatic-beneficiation technique may be advantageous in areas of limited water resource.

Jan 1, 1980

By David L. Veith

As the basis for the State of Minnesota's Regional Copper-Nickel Study environmental evaluation, hypothetical mine models were developed ranging in ore capacity from 5.35 to 20.00 x 106 mtpy. Open pit and underground mining operations were defined utilizing conventional methods of ore extraction. Processing of the copper-nickel sulfide material involved conventional bulk flotation of the valuable minerals, with maximum water recycle And tailing disposal. Flash smelting and electrolytic refining of the concentrate resulted in 0.10 x 106 mtpy copper plus nickel metal, plus associated cobalt and precious metals. Variations in model parameters allowed environmental trade-offs to be identified.

Jan 1, 1980

By R. R. Klimpel

The use of chemical reagents in flotation has been studied in great detail, e.g. (1, 2, 3, 4). Important progress has been made on the understanding of surface chemistry concepts involved in flotation. However, such scientific studies are often very complex even for rather simple idealized systems. Therefore, the deve- lopment of predictive or quantitative tools for plant engineering evaluation is still in the evolutionary stages. Until further progress in fundamental work is achieved, the operating engineer is faced with semi-empirical physical testing of reagent changes on several sizes of the actual equipment under study to be confident of the economic viability of any change.

Jan 1, 1980

By Donald D. Carr

Four counties in Indiana--LaPorte, Vigo, Vanderburgh, and Switzerland--have potential for deep underground limestone mining because they are in or are near high population areas and have no surface-minable limestone de- posits. The principal markets are Gary-South Bend, Terre Haute, Evansville, and Cincinnati. Minable seams suitable for aggregate are 120 to 150 meters (400 to 500 feet) below the surface in LaPorte and Vigo Counties, about 90 meters (300 feet) below the surface in Switzerland County, and about 600 meters (2,000 feet) below the surface in Vanderburgh County. Some deposits are also suitable for high-purity uses or for cement raw materials, which enhances their potential for exploitation.

Jan 1, 1980

By John J. Friel

The addition of dolomite to iron ore pellets improves their high-temperature reduction properties primarily by increasing their reducibility and raising their softening temperature. In this study we prepared dolomite-fluxed pellets from three different concentrates; Hibbing, a magnetic taconite, Knob Lake, an earthy hematite; and Carol Lake, a mixture of specular hematite with magnetite. The composition n of the concentrates is given in Table I. The pellets were subjected to standard physical tests and the following reduction tests: low temperature degradation, swelling, softening, and thermogravimetric analysis. Petrographic examination and electron microprobe analysis allowed us to evaluate the effect of composition and firing on the phase assemblage. Further, we were able to interpret the test results in terms of chemistry and microstructure. This approach enabled us to determine which fluxed composition best suited each of the concentrates.

Jan 1, 1980

By S. P. Banerjee

By international standards, Indian coal seams are not very gassy. In some of the major coalfields such as Singareni, Wardha, Pench, Chirimiri, Rewa and Talcher Coalfields practically no methane is emitted from the coal seams. Even in the coalfields of Ranigang, Jharia, Bokaro and Karanpura, all of which are situated in the basin of the Damodar river, only a few mines are faced with excessive gas emission problems. But the number of such mines is increasing as deeper reserves are being worked and already the exploitation of some of the best quality coal reserves in the country is held up pending measures for control of methane emission in these mines. Even in mines having no previous history of gas emission, methane has been met near dykes and faults. This was dramatically revealed by an explosion in Dhori colliery in 1965 wherein 268 persons got killed. Until that time, Dhori colliery was considered as a non-gassy mine but on that fateful day gas came to the workings through a freshly exposed fault plane. Similar incidences of ignition of firedamp in so-called non-gassy mines have also occured in the past, for example, in Chapui Khas and Samla Dalurband collieries, but the casualty figures were not as high. After the Dhori explosion, all Indian coal seams have been declared to be gassy, whether presence of methane is detected in the workings or not.

Jan 1, 1980

By-products are of greater importance in lead and zinc mining than in any of the other major base metals. While I think most mining people would accept that statement, you would probably get some widely varying estimates when attempting to quantify the value of by-products in lead and zinc mining. We are now able to do this with our lead-zinc mine cost model. This model was originally developed as a zinc mine cost model to help us forecast long-term zinc supply and price as part of a study we completed in late 1979 entitled "Zinc - The Next Decade". Before demonstrating the importance of by-product revenue to lead- zinc mines, let me first explain how the cost model was constructed. I will discuss the model as it was originally constructed - as a zinc mine cost model. It has subsequently been expanded to include lead only mines and now can Be run either as a zinc or a lead mine cost model.

Jan 1, 1980

By David D. Eyer

In today's world coal market, coal quality is becoming increasingly important. Often the coal quality parameters are one of the crucial considerations in the development of a coal mine. Because of the user's tighter specifications and because of strict environmental regulations, coal producers are being called on to predict with increasing accuracy, not only the quality of their product but also the variability of that quality. This area of reserve evaluation is naturally receiving a great deal of scrutiny. Consolidation Coal Company has developed reliable and sophisticated methods for predicting coal quality, but the company's efforts continue to search for even better techniques. The following is a step-wise summary of The methods currently used by consolidation coal company, with A recent project used as an example. Two of the newer, and as yet experimental techniques will be briefly discussed.

Jan 1, 1980

By R. M. Hays

Jan 1, 1980

By L. J. Buchanan

The relationship between hydrothermal ore deposits and hot spring systems has received intensive study in recent years, particularly as a consequence of interest in the energy potential of geothermal systems. Base and precious metal deposition in surface pools and at shallow depths in modern geothermal systems has been recorded in numerous publications (1, 2, 3) Theoretical studies of hydrothermal fluid flow at depth, connected to surficial hot springs systems, have been presented by White and others (1), Cathles (2) , Henley and McNabb (3). As a result of these and additional studies, numerous hydrothermal ore deposits are thought to have originated as genetic parts of larger geothermal systems. In particular, it appears that metal precipitation is greatly enhanced in zones of boiling where volatiles and steam are escaping (4). High grade, near surface concentrations of base and precious metals, deposited as a result of partial vaporization of rising fluids, are such a common aspect of modern not spring systems that ore deposition models are becoming based on what may be called a geothermal model. In its most general terms, this model requires an anomalously high thermal gradient which acts as the driving force behind a convecting hydrothermal system. The water may be entirely meteoric or may be In part at least of other origins. The water migrates towards the higher temperature area, becomes heated, and picks up alkalies and metals by dissolving minerals along the fluid path. As water exits to the surface above the heat source, a mass balance requires the incoming hot water to rise to replace the lost water. As the water rises past the elevation where the hydrostatic pressure is insufficient to prevent boiling, then boiling will occur. Depending on the salinity and the temperature of the water, boiling can occur anywhere from great depths to near surface. Boiling results in a loss of volatiles, a pH rise in the fluid phase, cooling of the remaining fluid, a rise in oxygen fugacity, a concentration of salts in the remaining liquid, and precipitation of ore and gangue minerals.

Jan 1, 1980

By P. J. Macbeth, R. F. Overmyer, K. K. Nielson

INTRODUCTION Over the past several years, Ford, Bacon & Davis Utah Inc. (FB&DU) has been involved in research, development, and engineering activities concerning uranium mill tailings; specifically of interest in this paper are efforts in radon gas exhalation and surface flux attenuation measurements, environmental influences on radon fluxes, and basic research into radon gas behavior. Our projects have included measurements of effectiveness of specific cover material in attenuating radon surface fluxes from mill tailings, characterization of the parameters in cover materials and tailings that influence radon exhalation, long-term tailings stabilization planning, determination of the effects of moisture on radon emanation and diffusion from ores, and determinations of baseline radon fluxes. Our efforts have been sponsored by U.S. Department of Energy, the U.S. Nuclear Regulatory Commission, Tennessee Valley Authority, the commercial uranium industry, and we are presently engaged in efforts for the U.S. Bureau of Mines. Much of the material presented in this paper is taken from our published reports on radon flux attenuation and tailings stabilization (Macbeth et al., 1978; Nielson et al., 1980; Rogers et_ al., 1980; Thamer et al al., 1980). CHARACTERIZATION OF RADON GAS EXHALATION One dimensional diffusion theory based on Fick's laws is the basis for the modeling of radon gas migration through large quantities of porous tailings and cover materials applied over the large areas of tailings piles. Fick's first law relates the gaseous concentration gradients to the flux over the entire surface and defines the effective diffusion coefficient De as: [ ]

Jan 1, 1980

By A. Wallace Mitchell

Barite deposits in Nevada occur as bedded and vein-types along a north-northeastern -trending zone which parallels the Antler orogenic belt The bedded deposits of Nevada are the most significant economically. They are presently supplying eighty-five percent of the domestic barite production which is used primarily as a weighting agent in the petroleum drilling industry. The ore bodies are controlled both structurally and stratigraphically, occurring along regional and local structural breaks in siliceous eugeosynclinal rocks of mid-Paleozoic age. Evidence for origin of the barite includes sedimentary and hydrothermal features indicating that localization probably took place along fractures in the seafloor.

Jan 1, 1980

By Steven T. Mitchell

The introduction of Vertical Crater Retreat (VCR) Stoping at the Homestake Mine in Lead, SD, constitutes a major advance in Homes take Mining Company's efforts to improve productivity and reduce costs through underground mine mechanization. The work to date indicates that Vertical Crater Retreat Stoping is one of the safest methods of underground hardrock mining today, and is competitive with all other forms of stoping in terms of cost and productivity. Homes take anticipates that VCR stoping rill account for approximately 30% of the total mine production in 1980.

Jan 1, 1980