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By Gordon B. French

Occidental's in situ retorting process for oil shale has many advantages over the conventional, underground mine and surface retort. Only a portion of the oil shale is mined and transported outside where it blends with the oil-shale talus found in the area. Spent shale is retained underground without surface disposal problems. The process consumes no water from outside sources. Noise and dust levels are kept at a minimum. As many of the facilities as possible are located underground. More oil is produced from a given area than conventional surface processing. Additional energy can be recovered by using conventional turbines to generate electrical power of magnitude of three to four times required by the operation.

Jan 1, 1977

By M. Van Hecke, Y. Berube, L. M. de Smecht

Nitrogen solubilities in water at 100, 200, and 400 psi, in the temperature range 100 to 175C, were determined using an automated system involving flash evaporation and gas chromatography. Rates of gas transfer into a standard laboratory auto-clave were measured by the same technique. The rates at which a gas can dissolve into such a reactor were found to be close to the rates of oxygen consumption observed during the oxidation of several mineral sulfides, indicating that gas transfer might be a rate-limiting step in autoclave leaching.

Jan 1, 1977

By S. Edward Drummond, Charles D. Haynes, Stephen H. Stow

This paper is a preliminary report on the occurrence and distribution of economically interesting heavy minerals (kyanite, sillimanite, staurolite, zircon, monazite, ilmenite, leucoxene, rutile) in sands from the sea floor surface of the offshore area, Alabama-Mississippi. Weight percent of heavies derived from the +60 portion of 97 samples is contoured in [Fig. 1]. Five hundred grains from 42 of the heavy mineral separates were identified and sized microscopically; the data were converted to weight percent for each mineral species and are summarized in [Table 1]. Heavy Mineral Distribution In the Gulf, there is a general westward decrease [(Fig. 1)] in maximum abundance of heavies from 2.4% north of Sand Island at the mouth of Mobile Bay to slightly over 1.0% south of Petit Bois Island and a corresponding decrease in the Mississippi Sound from 1.4%, north of Dauphin Island to slightly over 0.25% north of Horn Island. Average concentrations of heavies for different areas are found in Table 1. There is westerly longshore transport in this area; the interaction of the longshore current with discharge from Mobile Bay and disruptions of the current by Sand Island, possibly aided by a shoaling effect, appear to be the cause of the preferential deposition and concentration of heavies (2.4%) north of Sand Island in 10 to 14 ft of water.

Jan 1, 1977

By D. L. Paulson

The Bureau of Mines is investigating pyrometallurgica1 and" chemical methods to recover valuable constituents from metallurgical dusts and slags. Under this program a technique was developed to recover iron from molten copper smelting furnace slags by carbon injection. Slags from gas-fired reverberatory and electric copper smelting furnaces were treated in an 800-kva electric-arc furnace by injecting coke breeze into the bottom of the molten bath. Over 95 pct of the iron and over 90 pct of the copper contained in the smelting furnace slags were recovered, while up to 85 pct of the carbon injected into the system was utilized. It is anticipated that the metal product containing approximately 95 wt-pct iron and 2 wt-pct copper will be a satisfactory medium for recovering copper by cementation.

Jan 1, 1977

By D. H. R. Price

This paper presents two tentative models of the use of a notional metal in a country like Britian, which have been developed using the System Dynamics modelling method. Computer simulations have been carried out using one of the models. These show the effect on the recycling of the notional metal of a wide range of possible future values of world market price and demand for the metal.

Jan 1, 1977

By M. N. Dastur

In this paper, the current situation in iron ore pelletization in developing countries is reviewed. The main reasons leading to the development of pelletizing in these countries, alternative pelletizing methods and feed materials utilised, are illustrated with typical examples. The major factors which may influence the future growth are discussed and trends of development in the immediate future, till 1978, examined. The probable pelletizing capacity by 1985 is projected.

Jan 1, 1977

By H. W. Wevers

Fatigue failure and accompanying brittle failure occurs frequently in heavy mining equipment. This paper discusses how fracture mechanics can be applied as a tool for crack control and crack management. Information is provided to determine if particular components are prone to brittle failure. By using existing fracture mechanics formulae, an estimation of the critical crack size can then be made. It is explained that for a successful application of fracture mechanics, both the actual engineering stress in the component and the mechanical properties of the applied material must be known. The importance of toughness at low temperatures is quantitatively illustrated by calculating critical crack sizes at room temperature and at below-zero temperatures. Understanding the possibilities of fracture mechanics will also produce a climate in which the purchaser of equipment can more precisely analyze the relative quality of components with respect to crack tolerance and failure prevention. In this manner, communication between the user and manufacturer of equipment may also become more precise and effective, leading to improved design.

Jan 1, 1977

By Healy T. W, Dixon D. R

The present study 'of pure ZnS and NiS and ZnS (marmatite) by detailed electrokinetic methods has shown that by careful control of experimental parameters much new' information on sulphide-water interfaces can be obtained. Time-dependent processes of alteration of sulphide surfaces are foHowed by electrokinetic methods and indicate that the isoelectric point of the surface depends on elemental sulphur coverage, oxidation product coverage, and the conditions which promote or minimize such reaotions in the presence and absence of activator.

Jan 1, 1977

By Betty M. Miller

INTRODUCTION In September 1974 the Resource Appraisal Group of the Branch of Oil and Gas Resources, U. S. Geological Survey, was asked to aid the Federal Energy Administration (FEA) in its legal responsibility to generate by June 1975 an independent appraisal of the undiscovered oil and gas resources of the United States, both onshore and offshore. As a result, the Resource Appraisal Group accelerated its ongoing efforts to develop sound appraisal methods and procedures that would permit the systematic collection and evaluation of basic data from petroleum provinces throughout the Nation. The results of this independent appraisal of the Nation's conventional oil and natural gas resources were published by the U. S. Geological Survey as Circular 725, June 1975 (1). The estimates in this report of undiscovered recoverable oil and gas resources for the United States were made: (1) by carefully re- viewing a large amount of geological and geophysical information gathered on more than 100 different provinces by over 70 geologists within the Survey; (2) by applying a variety of resource appraisal techniques to each potential petroleum province; and (3) by application of subjective probability procedures to group appraisals for each petroleum province. These methods provide a range of estimates which are summarized in terms of low, high and mean values for the various provinces and groups of provinces, or regions. The basic data and procedures used are documented and are being incorporated into a dynamic, data- intensive system that can be upgraded, updated and reevaluated periodically. These data are open to public inspection. In this study, the primary emphasis was placed on conventional crude oil and natural gas in the onshore provinces and the provinces on the continental shelf out to water depths of 200 metres; estimates

Jan 1, 1977

By Ivor Hawkes

This report describes the results of a study to evaluate new design concepts for percussive rock drills that will result in quieter machines. It is shown that by incorporating such features as an efficient muffler, a plenum chamber integral with the machine body, and shroud tubes around the drill rods, etc., noise levels are reduced from about 114 dBA to about 95 dBA with very little change in drilling performance.

Jan 1, 1977

By Hunter T. C

The wirebar furnacing and casting facility commissioned in 1970 at Copper Refineries Pty. Ltd. (CRL), Townsville, comprising a 70 tonne/ hour ASARCO shaft furnace and a Walker type casting wheel, contained several unique design features. Since commissioning, effort has been directed at improving metallurgical control of the casting process. This has resulted in the identification of optimum mould lubricant properties and the use of continuous on-line measurement of molten metal oxygen content. Casting defects such as cracks and surface porosity are readily explained and controlled using these techniques.

Jan 1, 1977

By T. W. Peterson, J. W. White, E. E. Krist

In developing a minicomputer application for an industrial grinding circuit, the control program is usually coded and the compilation is debugged on a remote access computing system. Final debugging must wait for installation of the minicomputer. This work reports on an alternative. Here both compilation and execution bugs are eliminated before the hardware is installed by testing the control program against a dynamic simulation. Attention is directed toward development of a particular real-time control program for an industrial wet grinding circuit in a copper concentrator. Specific data were supplied by the Anamax Mining Co. for a grinding division consisting of a rod mill followed by two ball mills in parallel. This information was used to set up a plausible model structure.

Jan 1, 1977

By Nick Hasenack

In the pelletizing plant of Hoogovens, Estel BV, a varying mixture of hematites and magnetites is used for the production of acid and (occasionally) fluxed pellets. Optimum results regarding productivity, quality and process control are obtained with mixtures containing 30-40 % magnetites. A decrease of the magnetite ratio or an increase of the basicity has a great influence on both productivity and heat and power consumption. Tests have been carried out to find the extent to which magnetite can be replaced by b.f. dust, mill-scale and coke breeze. Pilot plant tests show that about 80-100 % of the production loss due to a decrease in magnetite content or to the increase in basicity can be regained without damage to the quality by adding coke breeze. The amount of coke breeze should be limited tot 1,5 %; if this percen¬tage is chosen higher, the quality of the pellets deteriorates rapidly. The amount of coke breeze to be added should be about 30 % above the theoretical value, based on heat balance considerations. The results achieved by incorporating b.f. dust and mill-scale into the pelletmix were also encouraging, but as some types of mill-scale are very difficult to grind and the supply of b.f. dust is limited, the research has not been carried out extensively in this field. The pilot plant tests on replacement of magnetite by coke breeze have been followed by industrial tests, during which the breeze was added to the ore feed before the dry-grinding system.

Jan 1, 1977

By G. J. S. Govett

World mineral production is dominated by six countries - the U.S., the U.S.S.R , Canada, South Africa, Australia and China - which also hold most of the reserves of the world?s minerals. For the developed and centrally planned countries, there is a strong positive correlation between the mineral production of a country and its land area: there is no correlation between mineral production and land area for the less developed countries. These facts imply that, after taking due account of geological controlling factors, a country may expect to produce minerals in approximate proportion to its land are a provided that political, economic, and historical factors are conducive to mineral exploration and mining. Contrary to popular political belief in many parts of the world, the developed countries are the major source of mineral imports for the industrialized countries. Moreover, exports of ores and minerals account for a relatively small par t of world trade, and are an important factor in the export picture of only a few of the less-developed countries. The looming resource confrontation between the developed and the less-developed countries is based largely on the false premise that the industrialized countries of the world are minerals-poor and owe their wealth to cheap minerals from the less-developed countries. The data presented refute this. Geological controls are relatively minor in the present distribution of world mineral production; political and economic factors are dominant. It is argued that an expansion of world trade in minerals - based on increased exploration and new forms of finance for mining ventures - rather than cartels, price-fixing and trade restrictions is by far the preferable solution to the problem of redressing the legitimate grievances of the poor countries of the world.

Jan 1, 1977

By J. R. Cooper

Since man began beneficiating ores, a limited number of factors influenced the type of treatment. The ore itself has always been a factor. The first form of concentration was probably hand sorting, and the grade of concentrate and recovery had to be considered from the start. The cost of labor as a factor in mill design did not attain importance until the period following World War I. Power was one of the cheapest commodities available, and consequently power consumption was ignored. That no longer holds true. The present work does nothing to simplify the work of the metallurgist, or designer. On the contrary it adds another element to the design considerations. And while this report concentrates on power consumption, the mill designer must take the other factors into account as well. This study is based on a compilation of data supplied by a number of Western United States copper operations, as well as information from equipment manufacturers. Although its conclusiones apply to other minerals and geographic areas, the information is more precise, when applied to similar ores. The discussion has been divided into sections covering crushing, grinding, and flotation as these are the principal power consuming functions.

Jan 1, 1977

By W. G. Dallas

The social and environmental problems presented by the location of a large zinc/ lead ore body within one mile of a thriving town are described. The development problems are social, involving the education of the in habitants , and environmental, requiring the development of a planning strategy and the evolution of a baseline and post -operational monitoring system. The necessity for an environmental-impact assessment and a thorough baseline study is emphasized. The continuing psycho-social consideration of community reaction is advocated.

Jan 1, 1977

By A. G. Matyas

Process improvements which have reduced the lead content of slag from the Brunswick lead blast furnace are described. Microscope examination and electron microprobe analyses, supported by the results of slag settling and viscosity tests, showed that typically about 70% of the lead in the lead blast-furnace slag was present in the form of entrained prills of metallic lead. The total lead content was found to increase with the magnetic susceptibility of the slag. Measurements in the furnace settler indicated the presence of a magnetite-rich layer between bullion and slag, arising from high magnetite levels in the slag. This layer was believed to inhibit the settling of entrained lead from the slag. Tracer tests showed that the average slag residence time in the settler was less than 2 minutes. Improvements in coke quality and sizing, which led to a reduction in the slag magnetite content, and the installation of a larger settler and a continuous Roy tapper, have all contributed to a significant decrease in the slag lead content.

Jan 1, 1977

By Arnold J. J

The design of a coal preparation plant using bore core data cannot be discussed without some reference to the wider considerations of design. A thorough knowledge of coal preparation processes and processors as well as ancillary equipment is essential if the coal properties determined from bore cores, are to be fully utilised. Whilst generalised information of processes is available from a wide range of publications and equipment suppliers for the intending plant designer, local operational experience must be taken into account where there are similarities. However it would be wrong to assume that satisfactory plant design can be achieved merely be repeating previous design parameters. A detailed examination of bore cores used in conjunction with well proven design 'criteria will identify important differences in design parameters without which efficient and economic plant/sectional sizing cannot be achieved.

Jan 1, 1977

By G Luxbacher

Computer simulation of mine ventilation systems is rapidly becoming an essential tool in mine planning and design. This paper examines the utilization of ventilation simulation techniques to evaluate the number, shape, size and layout of mine entries in a typical coal mining system. Since the mains and sub-mains serve mainly for transportation and ventilation and the ventilation system is critically important to the health and safety of the workers, there exists a great need for optimal designs in this area. Evaluation criteria, could include, among others, minimization of power costs, shaft requirements and leakage. Constraints of this optimization problem include health and safety regulations and production and mine infrastructure requirements.

Jan 1, 1977

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

Comprehensive ventilation surveys are made to review the adequacy of the mine system with regard to both statutory requirements and/or company policy, to evaluate improvements to the current ventilation system and to plan for £stun expansion. If computer simulation is to be used for these purposes, accurate quantity and pressure measurements become an absolute necessity since the validity of the computer generated output is heavily dependent on the accuracy of the input data. Consequently ventilation surveys that are run to generate input data for computer simu¬lation must use the best data collection procedures to guarantee as accurate results as are possible. These requirements have led to modifications in procedures that are used for routine ventilation surveying. McElroy and Kingery (1957) have recommended that pressures be measured independent of quantities since minor changes in mine conditions have a greater effect on absolute pressure measurements than on quantity measure¬ments. They estimate that, for large mines, a pressure survey may take only 1 to 3 days while the corresponding quantity survey would require 1 to 3 weeks. Although this procedure would undoubtedly lead to more ac¬curate pressure measurements, its use for the development of computer input data is not recommended for the following reasons. Atkinson's equation, H = RQ2, is used in computer oriented analysis to develop the airway resistance, R, based on quantity and pressure loss measure¬ments. It can easily be seen that since R a 1/Q2 and R a H, the effect of errors in quantity measurement is, in fact, more significant than those in pressure measurement. If the quantity and pressure measure¬ments are made at different times another problem results. Minor changes in quantity that may occur in the time between the pressure and quantity

Jan 1, 1977