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Radioisotope x-ray methods for the on-stream determination of copper, lead, and zinc in mineral product slurries were developed, and were successfully tested at the plant of Cobar Mines Pty. Ltd.The tests were made in three stages. Measurements to determine the precision of analysis were made initially on briquettes of the mineral products. The effect of slurry solids content variations was then determined by measurements on the mineral products in a recirculating slurry loop. The radioisotope analyser was finally tested in a series of on-stream measurements in the plant.Copper, lead, and zinc in flotation feed and in copper concentrate were determined to a precision ranging between 1·4 and 15 per cent of the mean element concentration in the slurry solids. These precisions are within limits required for plant control purposes at Cobar.

Jan 1, 1971

By John V. Beall

Never having done it before, it took us all day and until 11 at night to select and pack for a four-day back- pack trip up Lake Chelan last month. When we were through, we couldn't lift our own pack and Sylvia's, OUT spouse's, we barely managed to budge. Nevertheless, the next morning we were at the dock to board the Laldy of the Lake for the 3 ½ -hr boat trip to Lucerne. Our dress and accouterments creating the appearance of a veritable expedition into the wilderness made a sharp contrast with our fellow passengers, a senior citizens tour group from Spokane. We had come out to Seattle for the SME Fall Meeting and were taking advantage of the occasion for a vacation trip back to Lucerne and Holden where we had lived briefly 25-years ago, and a backpack trip up Railroad Creek from Holden to the Glacier Peak country, weather permitting. No matter what you say, weather is important, and this is one of the ingredients that went into making the SME Fall Meeting and Exhibit in Seattle, September 22-24, a thoroughly delightful experience for the 700 plus persons who attended. Seattle is a beautiful city, but with late September sunshine, which we experienced, it is the best. The second ingredient, is a swinging host committee. Under the leadership of Don Anderson and Tom Van Zandt, co-chairmen, and Mrs. Cecilia Reed, Ladies Program, superb hospitality and fine arrangements were blended. Earl Beistline, from Fairbanks, organized a two-day short course on arctic operations which preceded the meeting and drew an attendance of 44. Dick Robbins, in charge of arrangements, provided Masters-at- arms for technical sessions and a presentation of the colors by the U.S. Coast Guard at the Welcoming Luncheon. Eric Cheney's field trips ranged far and wide with events both before and after the meeting. David (Jeff) Kroft, capably managed audio-visual operations with a group of students from the University of Washington. Charles Hochmuth worked long, hard and effectively before and during the meet- ing on finances. Hank Reed, managed an authentic three-ring circus as Entertainment Chairman. His activities covered two cocktail receptions for all registrants and a dinner-dance. Dolph Campbell and Joe Hackbarth provided publicity by press and TV (see p. 37-40). SME's meetings have certain characteristics and possibly not all of these are known to everyone. The first of these is the deliberate involvement of the AIME Section in the area of the meeting. Most trade shows and conventions are run 100% by a professional staff and although SME staff could also do this, it has been our experience that a more friendly and better meeting results when the local members apply their talents. Actually SME only considers a site for a meeting after it has received an invitation from a Section. The knowledge of local conditions which Section committeemen bring to a meeting is of great value.

Jan 1, 1971

By C. H. Larsen

A 9-month study of the uses of wire rope associated with U. S. underground coal mining is reported. Rope applications are broken down into hoisting and nonhoisting applications where "hoisting" refers to transport in vertical and inclined shafts. The former receives the greatest emphasis since it represents the most critical rope application from the stand-point of production and safety. The discussion of hoisting practice includes aspects related to the mine operators as well as those related to the equipment builders and wire rope manufacturers. U. S. state and Federal laws regulating hoisting and wire rope use are also presented and discussed. Canadian and other foreign hoisting practice and laws are included. The state of the art in electromagnetic nondestructive inspection of hoist ropes is presented. Capabilities and use of one Canadian electromagnetic device are discussed in great detail. Conclusions are drawn regarding the present state of wire rope and hoisting technology in U. S. coal mines. Recommendations are made for improving rope practice, in general, and hoisting, in particular, consistent with greater safety.

Jan 1, 1971

By John G. Parker

The rare-earth elements, sometimes known as the lanthanides, comprise the series of 15 chemically similar elements with atomic numbers 57 through 71. Yttrium, with atomic number 39, is often included in the group, because its properties are similar and it more often than not occurs in association with the lanthanides. Thorium is included in this survey due to its close association with the lanthanides, particularly in the mineral monazite. The lanthanides were first recognized as elements around 1750 and were the subject of much study by chemists during the 19th century. The purely chemical methods then available failed to resolve the strange intimate relationships between these elements, and it was not until about 1920 that the full series was explained.

Jan 1, 1971

By L. A. Neumeier

The Bureau of Mines evaluated the properties of zinc alloys containing 25 to 40 wt pet Al and 0 to 0.7 pet Mg. Microstructures, hardness, and tensile properties were evaluated for material as extruded at 285° C, solution treated at 300° to 400° C, and subsequently aged at 100° to 200° C. The alloys without magnesium are characterized by low hardness and strength with high tensile elongation and reduction in area. It was verified that magnesium effectively retards the Zn-Al eutectoid transformation below 275° C and markedly increases hardness and strength with decreases in ductility. Solution treating at 350° C results in large grain sizes and gross embrittlement. Subsequent aging of the Zn-Al-Mg alloys at 200° C restores ductility substantially and stabilizes the structures, but strengths are considerably reduced. Combined strength and ductility properties are better for the as-extruded condition than for any heat-treated condition. There is usually little advantage in overall tensile properties from increasing magnesium above 0.1 pct.

Jan 1, 1971

By Damon C. Gray

This report contains a recommended program of acoustic research to be conducted by the U. S. Bureau of Mines. The program is directed toward the abatement and control of machinery noise in underground coal mining operations. The study conclusions and specific problem areas which led to the definition of the recommended program are also briefly described.

Jan 1, 1971

Since early 1968 the Bureau of Mineral Resources (B.M.R.) has carried out VLF-EM test surveys in various parts of Australia and Papua. The aim of the work, primarily, was to examine the effect- iveness of the method as an exploration tool under a variety of Australian conditions. Selection of test areas was determined by the availability of geological, geophysical and drilling information and by the desirability to include a variety of physical variables such as depth of weathering and topography. The aim of the present account is to review the results of this work and to make an assessment of the method available to the mining industry. The author wishes to acknowledge considerable assistance both by way of data and discussion provided by Messrs. Paul Gillespie (B.M.R.). and John Haigh (formerly B.M.R., now Senior Geophysicist, McPhar Geophysics Australia.) The article is presented with permission from the Director, B.M.R.

Jan 1, 1971

By E. A. Farrell

A comprehensive survey is made of the status of the asbestos industry as it relates to marketing the product. Included are descriptions of the various types of asbestos and the grading and classification systems used. The uses of asbestos, distribution practices, and types of ore bodies are all related to marketing. World production, the producers and their capacities and world consumption for 1966-67 are summarized and statistical data are included. Asbestos is a general term describing a family of fibrous minerals of the serpentine and amphibole mineral groups. Asbestos has a long history going back to the time of the Egyptians, when it was used as a lamp wick. The commercial mining of asbestos started in Canada, Russia, and Africa in the 1800's, and the first asbestos products were made in Italy and Russia. The five main types of asbestos are: chrysotile, accounting for 95% of the total mined, amosite, crocido-lite, anthophyllite, and tremolite. Canada, Russia, and Africa are the major producers of asbestos. The commercial utility of asbestos was at first based on the heat resistance of the fibrous mineral in the form of packing, at the start of the industrial revolution. Its current utility is based more on its ability to reinforce binders such as portland cement, rubber, and plastics. Its inertness to the chemical nature of most binders is unique. Most important is its ability to maintain its reinforcing utility when the product is exposed to weather and soil conditions as in asbestos cement boards and pipe, and heat, pressure, and chemical exposure as in brake linings and gaskets and packings. The mineral asbestos is also unique because its fibrous form permits it to be spun and woven to cloth or formed into paper. Many asbestos applications are critical to national defense and at the present time, there are no satisfactory substitutes. Grading and Classification Canadian chrysotile asbestos fiber is graded and priced by length since basically the longer the fiber the higher the utility. The Canadian asbestos industry does not, however, classify the fiber by direct length measurement, but by a dry screening test. The method is called the Quebec Standard Screen (QS) test. One pound of fiber is mechanically shaken in four vertically stacked sieve boxes. The relative proportions remaining on the sieves defines the grade. The longer the fiber, the larger is the amount that stays on the top coarse screens and the less on the lower, finer mesh screens. Other tests can be used to further define the length distribution of fiber such as the wet screen Bauer McNett and the Suter Webb Comb (3 group only). The Canadian grading system divides the milled fibers into 5 main groups: group 3, 4, 5, 6, and 7, with 3 group being the longest, and 7 the shortest. Each group is further divided to subgrades, identified in each group by the letters A to Z, with "A" the longest and "Z" the shortest. See Appendix 1 for the Canadian QS classification system. The Russians also use the QS test on chrysotile. The Africans classify their chrysotile into grades similar to Canadian. The African crocidolite and amosite, however, are classified into actual length groups such as l to 2 in. and 2 to 3 in. Amosite and crocidolite are generally longer than chrysotile but also more brittle. Milled asbestos is not composed of staple length fibers like fiber glass or cotton, but of a mixture or blend of fibers ranging from long to short. Milled asbestos has a fiber length distribution similar to the particle size distribution of a powder. For example, the longest group 3 chrysotile grades have a high percentage of the longest fibers (1/2 to 3/4 in.) and low percentage of short fibers (0.003 in.). The figures in Table 1 give the approximate length distribution of the longest, middle, and shortest groups. A second and further method of classifying fiber is the degree to which the fiber bundles are separated to form a larger number of smaller diameter bundles. This property is normally described as the degree of fiberization, openness or surface area. Air permeability tests are used to measure surface area. Asbestos pro-

Jan 1, 1971

By Homer S. Frankhouser

Materials may be dredged, processed, stored and loaded for shipment at a single site in water depths ranging from 250 to 1200 ft. Solution mining may also be accomplished in deep sea situations. And, open air subsea mines with direct surface access may be developed and worked under the ocean floor. These concepts for deep sea mining are the results of extensive testing of individual components of the proposed systems by Dravo Ocean Structures, Inc., a subsidiary of Dravo Corp. A basic structure in these systems is the articulated platform. The platform consists of a gravity- type base and a buoyant cylindrical column which is constructed at an onshore location, towed to the offshore site and installed in a matter of days without use of heavy equipment. The base is also buoyant for towing purposes. This allows for gradual flooding to the point of negative buoyancy for positioning and anchoring to the ocean floor.

Jan 1, 1971

The design, specification, and performance evaluation of the Communications and Location portions of a Coal Mine Rescue and Survival System are described. The work was performed as part of a nine month effort to develop a mine rescue and survival system using existing technology and state -of-the -art hardware as recommended by the National Academy of Engineering. Three basic subsystems were developed, one for survival, one for communications/location and one for rescue. This report and related equipment manuals describe only the Communications/ Location Subsystem which was designed, fabricated, and tested by the Westinghouse Georesearch Laboratory in Boulder, Colorado. Two basic technologies were used. Electromagnetic signals propagating through-the-earth provide voice downlink and coded beacon up-link communications. Seismic methods were developed to provide means for locating trapped miners. Seismic signalling also provides a backup means for communications. Parallel development programs for the electromagnetic and seismic portions of the system were conducted. The resulting hardware and software have been partially tested in coal mines and under simulated emergency conditions in order to evaluate system performance. The results of these tests are discussed. Further testing is recommended in order to establish quantitative performance limitations tinder a variety of environmental conditions and to develop methods for improving system performance.

Jan 1, 1971

By L. E. Cardwell

This publication contains routine analyses and related source data for 377 natural gas samples from 19 States and two foreign countries. Of this total, 373 samples were collected during calendar year 1970. The remaining four samples were collected during previous years, but releases granting per-mission to publish the analyses were not received until 1970. All samples were collected as part of a continuous survey of the free world for occurrences of helium in natural gas. This survey has been conducted in the United States by the Bureau of Mines since 1917. In late 1965, the survey was expanded to include foreign gasfields. The analyses published herein were made by mass spectrometer and a special helium analysis apparatus, which are described in Bureau of Mines Bulletins 4863 and 576.4 Twelve previous publications have presented the results of 9,050 gas analyses prior to 1970. The first three, Bulletins 486,6 576,8 and 617,7 contain analyses and related source data on 5,218 gas samples collected from

Jan 1, 1971

By B. J. Dalton

The Bureau of Mines Helium Research Center has developed a computer program for solving two-phase equilibria data for binary mixtures and for evaluating thermodynamic functions of interest, including all critical points. This computer program was used to calculate equilibrium points on the PVTu surface for the helium-nitrogen system as predicted by the Van der Waals equation of state. Numerical values are tabulated and illustrations are presented for 1,279 equilibrium points and for quantities needed to construct Ponchon diagrams. Equilibrium ratios as a function of pressure at constant temperature and of temperature at constant pressure-are also shown graphically. In addition, saturated partial molal volume and partial molal enthalpy data are given. It is shown that the Van der Waals helium-nitrogen system exhibits retro-grade condensation of the second type for liquid helium concentrations of about 0.07 mole fraction or less and pressures below about 45 atm. It is also shown that the critical point is at a -maximum value of pressure (at constant temperature) and of temperature (at constant pressure).

Jan 1, 1971

Presented in this volume are the basic mining techniques and production operations associated with underground bituminous coal mining. Chapter 2, "Multiflow Process Charts", presents, in sketch form, a description of the various operations characteristic of conventional and continuous mining. In order to focus attention upon the major components and operations in each work cycle, certain items are not shown in the sketches, e. g., machine electrical cables, brattice, and rib posts. The elapsed time shown for each sketch is considered representative for the various work elements summarized by the sketch. More detailed work element times can be found in Chapter 3, "Typical Work Cycle Times", and Chapter 4. "Standard Time Data".

Jan 1, 1971

By Y. L. Su

Deterministic and stochastic simulation were combined to develop a computer model of an open pit mining system using bucket wheel excavators and related materials handling equipment. The model is closed and dynamic in the sense that information is fed back to control activities at various levels and reservoirs. The results of interaction between unit operations in one time interval determines overall system behavior for the next interval. Equipment performance curves and system profile characteristics rather than time studies are applied to determine the operation of each activity at any time period. For that part of system where performance is dictated by a random variable~ subjective probabilities are employed. Two stages of research were considered to formulate this model. Stage one involved the formulation of equipment sub-assemblies for the sequence of equipment moves along with related assignments and routines for information retrieval. The second stage of research combined all sub-assemblies into an integrated open pit mining simulator. The model is not tailored for any specific open pit operation but is readily adaptable to any system of surface mining including operations having a high degree of complexity. Questions answered by the model include: 1) system design and selection of equipment for a new mining operation; 2) analysis of existing operations for possible changes, additions or general

Jan 1, 1971

The strippable reserves of bituminous coal and lignite in the United States were calculated in accordance with the prevailing conditions of seam thickness and depth of overburden in each of the several coal-producing areas of the Nation. Within defined limits of seam thickness and depth of overburden, it is estimated that there was a remaining strippable resource of 118 billion tons of raw bituminous coal and lignite as of January 1, 1968. Because of topography, natural and manmade features, and other limitations, only 45 billion tons of the resource are strippable reserves. Of this, 32 billion tons is considered low-sulfur (less than 1 percent), 4 billion tons is medium-sulfur (1 to 2 percent), and 9 billion tons is high-sulfur (over 2 percent) coal. Owing to a cleaning loss affecting that portion of strip coal that is mechanically cleaned, the 45 billion tons of strippable reserves are reduced to 39.6 billion tons of marketable coal. A brief discussion is given for each coal-producing State, summarizing past and present production, historical background, and outlook. Appendix A contains reserve data by State, county, seam, and sulfur content. Appendix B contains the general information and requirements necessary to comply with the current strip mining laws covering 20 States.

Jan 1, 1971

In 1970, the U. S. Bureau of Mines contracted with Theodore Barry and Associates, a management consulting firm, to perform a one-year industrial engineering study of working-face hazards in underground bituminous coal mines. The field data was accumulated from industrial engineering observations in fifty underground mines. Supporting data for the analysis was derived primarily from the Bureau's fatal accident reports for the years 1966 through 1970. This report, Industrial Engineering Study of Hazards Associated with Underground Coal Mine Production, consists of three main parts: 1) The Fatal Accident Reports Analysis, 2) The Industrial Engineering Analysis, and 3) Multiflow Process Charts and Standard Time Data. The Fatal Accident Reports Analysis (Volume I, Section II) is based upon individual USBM fatal accident reports for 1966-1970. These were read, coded and computerized in terms of 84 significant variables. Cross-tabulations of these variables have been used to identify major underground hazards and to quantify significant causal factors. A very strong relationship was found to exist between fatal accident occurrences and low task experience. This led to a recommendation for formalized training, certification and supervision programs for miners. Victim compliance with federal regulations, mine regulations and supervisor instructions was analyzed, indicating that supervisors provide the most crucial communication link to workers. Thus, every attempt should be made to ensure the competence of immediate supervisors in the industry. Analysis of roof fall variables revealed a fatal propensity on the part of the miners to work under unsupported roof or under support conditions that are marginal. The technical approach to the problem is to make it physically impossible for a miner to work under these conditions; the behavioral approach is to ensure adequate training and develop proper safety attitudes among the miners. The Fatal Accident Reports Analysis revealed a need for normalizing data to interpret the results more accurately.

Jan 1, 1971

By Jan Zwarcendyk

This study is primarily directed toward providing an understanding of the economic complexities associated with subsidence damage on the surface resulting from underground mining. Some of the pertinent theories on the physical stresses involved are reviewed, and both remedial measures and relevant laws in various countries are discussed. Part I (Chapters 1-3) is an historical overview of various aspects of subsidence problems (theoretical, remedial, and legal) during pre-World War I, between World Wars, and post-World War II, respectively. Part II (Chapters 4-9) presents a comprehensive analysis of the economic aspects of subsidence in relation to the following mining alternatives: (a) carrying out the lowest cost mining method without regard for any surface subsidence, (b) special mining techniques, (c) partial mining, (d) full recovery with stowing, and (e) sterilization or leaving the mineral unmined beneath selected areas. These alternatives are evaluated in terms of their measurable expenses.

Jan 1, 1971

By Carl L. Bieniewski

In a Bureau of Mines supply evaluation, the known uranium resources in the United States are estimated to have a total recoverable uranium oxide (U3O8) content of 3,132,400 tons at prices up to $69.32 per pound. Only those resources were evaluated for which sufficient quantity data are available and process technology exists for recovering uranium. A total of 160,800 tons of U3O8 is available at $8 per pound from ore deposits presently mined and an additional 244,700 tons available at prices up to $30 per pound from similar but usually lower grade deposits. A total of 2,726,900 tons of U3O8 is available from four other resources: copper leach solutions, wet-process phosphoric acid, Florida phosphate rock Leached zone, and Chattanooga Shale. These resources contain from 30,000 tons of recoverable U30, at a price of $7.52 per pound as a byproduct of copper leach solutions to 2,557,300 tons at a price of $69.32 per pound from Chattanooga Shale.

Jan 1, 1971

By W. R. K. Wu

Results of linear correlations of two to four variables by the least-squares method are presented. The variables include 63 parameters representing coal composition, coal plasticity, and coke strength. The composition parameters are on chemical analyses; the plasticity parameters, on three plastometer and dilatometer tests and four miscellaneous tests; and the coke-strength parameters, on three ASTM indices. Seventy-two to eighty-four plastic coals were used in the plasticity and carbonization tests, which together form the basis of this report; 43 nonplastic or weakly plastic coals were used in the coal-band studies. Plots of relations between volatile matter, carbon, and oxygen contents of 1,860 U.S. coals and the 84 coals used are shown. Similar plots between volatile matter and hydrogen or atomic H/C of the 84 coals are also included. Significances of regression coefficient signs for coal composition parameters in the significant correlations found are discussed. Based on these significances, the following relations are shown: (a) coke strength versus average aromaticity, or mineral matter content, of the parent coal; (b) characteristic temperatures of the plastometer and dilatometers, the free-swelling index, or the Gray-King type versus average hydroaromaticity of the coal; and (c) nontemperature parameters of the plastometer and dilatometers versus the physical properties of a certain group of compounds from thermal decomposition of coal. Similarly, significances between the positions of coals in the coal band and the aforementioned relations are also discussed. A structural theory of coal plasticity is proposed. Applications of the correlation results are discussed. Composition parameters, such as carbon, atomic H/C, and calorific value may be used as a basis for selecting coking coals for stronger coke. Plasticity parameters, such as the end temperatures of the plastometer and dilatometers and the free-swelling index, may be used for the same purpose. Based on the best correlations found, coke-strength indices may be estimated to within 4 to 8 units of the observed values; the end temperatures of the plastometer and dilatometer tests, 5° to 10° C.; and the free-swelling index, within 1 unit. Accuracies of all these estimated values are examined, based on the experimental errors of the data involved. Finally, estimations of plasticity parameters from one test with those from others are shown.

Jan 1, 1971

The interaction of flotation collectors with sulfide minerals takes place at the solid - solution interface. The electrochemistry of the processes which affect this interface are discussed. The interaction of xanthates with sulfides is an electrochemical process, xanthates being electro-oxidised to chemisorbed xanthate and dixanthogen. The role of oxygen is to provide a cathodic process to allow the anodic oxidation to occur. The hydrophobic condition of the mineral surface is brought about by the presence of the oxidised xanthate species. The action of reagents which can activate or depress the flotation of sulfides is discussed briefly.

Jan 1, 1971