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By Jr. Abel

Subsidence is controlled by a complex combination of mining and geologic factors. For example, a world-wide compilation of data shows that, as the percentage of shale in the overying rock mass decreases and the amount of sandstone increases, the angle of draw (and the area affected by subsidence) decreases. Limestone in the overburden appears to cause as much as a three-fold decrease in the angle of draw compared to a like amount of sandstone. Increased amounts of sandstone were accompanied by a greater surface subsidence relative to the mining height. The total thickness of overburden did not appear to influence the subsidence magnitude above super-critical panels. The greater the thickness extracted the smaller percentage of that thickness that shows up at the surface as subsidence. The greater the percent of the seam extracted, the greater the subsidence reaching the surface. The maximum subsidence above room and pillar panels is dependent on the pillar height and minimum width as well as the other factors listed.

Jan 1, 1980

By James R. Cosby

This report describes work performed for the Bureau of Mines to evaluate available portable instruments for their effectiveness in detecting and locating damaged metallic shields in Types SHD and SHC cables. A second phase of the program is also covered wherein several instruments of a type which show promise are purchased for modification and testing to verify their performance.

Jan 1, 1980

New Trade Status for Mainland China--On January 24, the Congress approved a most-favored-nation trade status with Mainland China for both imports and exports. A Presidential Proclamation had been issued earlier in anticipation of the Congressional action. Import duties on such commodities as tungsten, mercury, and antimony are automatically decreased. Defense Production Act Extended--The Defense Production Act of 1950 was extended 60 days to March 28, 1980. The provision for the usual 2-year extension of the Act is reportedly included in an omnibus energy bill that is tied up in committee. The Act under Title III provides for the expansion of productive capacity and supply and, more specifically, it gives priority to defense contracting where defense and non-defense interests conflict

Jan 1, 1980

Dry weather since the third week in January has set back any prospects for an early increase in hydroelectric power in the Pacific Northwest, according to The Bonneville Power Administration. The 25% cutback made in July probably will not be restored in March or April. Noranda Aluminum, Inc., increased its price for 99.5% aluminum ingot from 66 cents to 70 cents per pound effective March 1, 1980. Revere Copper & Brass, Inc., also -increased its price for primary aluminum from 66.0 cents to 70.0 cents per pound effective February 1. Kaiser Aluminum & Chemical Corp. raised its international price for 99.5% primary aluminum from 72.6 cents to 82.6 cents per pound, c. i. f., effective February 26 on new orders and on shipments from March 15.

Jan 1, 1980

By George Chung

"The Iron Ore Company of Canada's Carol Lake Project is Located near the western boundary of Labrador, 960 air kilometers northeast of Montreal (Figure 1).The Concentrator operation was started in 1962 with a capacity to produce 7 million tonnes of concentrate per year. The bulk of the concentrate was pelletized at a 6 million tonnes per year pelletizing plant completed in 1963. The remaining concentrate was sold in the international market. The concentrator was first expanded in 1966 to 10 million tonnes per year capacity with the pellet plant also expanded in 1967 to match the increase in concentrate production. In 1973, the concentrator was further expanded to gear with the increase in concentrate sales. In 1977, more than 40 million tonnes of crude ore was processed to produce in excess of 17.4 million tonnes of concentrate and 10.4 million tonnes of pellets."

Jan 1, 1980

By William H. Pomroy

Fire on surface mining equipment is a serious hazard to life and property. The Bureau of Mines, through a program of contract and in-house research, has developed and in-mine demonstrated reasonably priced, reliable automatic fire protection systems to deal with this problem. This report reviews the development and subsequent testing of systems for haulage trucks, front end loaders, coal augers, dozers, drills, and shovels. A variety of fire sensors, extinguishing agents, and control systems arc discussed in the context of mine equipment designs and operating environments

Jan 1, 1980

By Gordon M. Miner

When I was originally invited to speak to this audience on the subject of the future supply of precious metals I was somewhat apprehensive and suggested that the Program Chairman select someone with more credentials. He declined and the results of our conversation gave me cause to reflect and recall the opportunities I have had over the years and how fortunate I have been to be associated with so many successful companies and knowledgeable people affiliated with the precious metals field. I discovered that since 1935, 1 have worked in or visited most of the gold and silver camps in the United States; have been a leaser of a gold mine in Mohave, California; have both lost and made money in the silver futures market; have worked for two of the greatest precious metals companies in the United States - Homestake Mining Company and Hecla Mining Company, have spent a considerable amount of time in precious metal related discussions with men like Don MacLaughlin, Paul Henshaw, Dick Stoehr, Abe Shoemaker, Bill Love, Phil Lindstrom, Simon Strauss, Herbert and Bunker Hunt and many others. It is those exposures and experiences that I draw onto discuss the subject at hand.

Jan 1, 1980

By V. J. Sopuck, O. P. Lavin, Ian Nichol

"A major challenge of contemporary exploration geochemistry is the development of procedures that can locate blind mineralization or mineralization that sub-crops below a cover of transported overburden, the composition of which bears no relation to the underlying mineralization. Over the past few years, the possible existence of diagnostic geochemical features in the country rock associated with volcanogenic massive sulphide deposits has attracted increasing attention both on the local mine scale and on the regional scale. In the present investigation, the nature of the geochemistry of a number of Archean greenstone belts of the Canadian Shield is examined to determine the feasibility of distinguishing productive from non-productive areas of copper-zinc mineralization. The results indicate that productive areas are distinguishable from non-productive areas providing consideration is given to the effects of igneous differentiation on rock compositionIntroductionArchean massive sulphide deposits are an important source of copper and zinc, and to a lesser extent silver and gold, particularly in Canada. As in the case of most other forms of mineralization, there is a continual need to develop new techniques that will improve the chances of success in the search for these deposits. The majority of Archean areas in the northern latitudes are overlain by a variable cover of glacial overburden. Considerable progress has been made in the development of new geochemical exploration techniques for use in glaciated terrain, based on the detection of anomalous dispersion in the glacial overburden. In certain situations, however, as in the search for blind deposits or in areas covered by glaciolacustrine deposits, overburden geochemistry offers little hope for success. In the case of massive sulphide deposits, one possible solution may lie in the detection of anomalous geochemical signatures in the bedrock. Recognizing this possibility, attention has been directed to the investigation of the nature of lithogeochemical dispersion associated with massive sulphide deposits on both regional and local scales, to establish the potential of lithogeochemistry as an aid in the search for these deposits."

Jan 1, 1980

Duty on Lead Reduced. -On December 28, the President signed H.R. 5047 which reduces the duty on unwrought lead from 3.5% ad valorem to 3% ad valorem, with a floor level of 1.0625 cents per pound, effective retroactively from January 1, 1980, through June 30, 1983. Pacific Northwest Power Bill Passed. -On December 5, the President signed S. 885 which will enable the Bonneville Power Administration to guarantee 20-year contracts to its 15 major industrial customers in exchange for higher rates. In effect, the bill will have industrial customers pay some of the costs of building additional generating facilities in the Northwest, of which thermal units are expected to be a major part. BPA supplies power to six primary aluminum producers which operate eleven plants having over 30% of the primary aluminum capacity in the United States.

Jan 1, 1980

New GSP Trade Status Approved.--President Carter, by Executive Order effective March 30, has approved Generalized System of Preference treatment for imports of nonferrous metal products and other imports from Ecuador, Indonesia, Zimbabwe, Uganda, and Venezuela. As of May 2, Afghanistan and Ethiopia will be taken off GSP status. Under the Generalized System of Preferences, certain imports from developing countries are provided duty-free treatment. A country can lose its GSP status if its shipments of the product exceed $41.9 million or more than 50% of total U.S. imports during the preceding year. However, the President can waive the 50% rule in cases where total U.S. imports of an item in 1979 were less than $1 million. Certain nonferrous imports from Mexico, Peru, Chile, and Zambia are already covered by GSP. Hearings April 10 on International Tin Agreement.--The Fifth International Tin Agreement of which the United States is a signatory, which entered into force on July 1, 1976, will expire on June 30, 1981. A negotiating conference for a Sixth International Tin Agreement will be held under auspices of the United Nations at Geneva from April 14 to May 16, 1980.

Jan 1, 1980

Lead Tariff.--The full House Ways and Means Committee approved H.R. 6089 which will have the effect of reducing the tariff on unwrought lead to 3% ad valorem, with a floor duty of 1.0625 cents per pound, compared with the currently effective rate of 3.5% ad valorem. Consideration is also being given to tariff rates on imports of red lead and litharge from Mexico. A consortium of domestic producers has appealed to the Office of the Special Trade Representative (STR) requesting a return to tariff schedules which were in effect prior to the concessions made effective on January 1. Mexican producers have filed a proposal in favor of lower duties, and the matter now awaits a ruling by the STR. Ferrous Scrap Exports.--After holding public hearings and receiving public comments in May, the Department of Commerce announced that it would not institute formal monitoring of ferrous scrap exports, as requested by the Ferrous Scrap Consumers Coalition. The Department said, however, that it would follow the trend of scrap exports and prices. Ferrous scrap prices are currently low and supplies are reported to be adequate.

Jan 1, 1980

By J. B. Stott

The performance of an adiabatic calorimeter for measuring heats of oxidation of coal is assessed and suggestions made for its improvement and calibration. The use of magnetic analysers for measuring small oxygen deficiencies in air is described and three different methods of measuring the output for such a meter are characterised. The occurrence of spontaneous heating in an 800 tonne heap of Wyoming coal is briefly described. The major part of the report deals with the oxidation of Pittsburgh seam and Wyoming subbituminous coal and describes an experiment in which 1 tonne of Wyoming coal is stored in a 5 metre long insulated container whilst air was passed through. Temperature rises, rates of oxygen absorption and gas compositions of the air stream were measured. The report relates the results of these-experiments to a theory of spontaneous heating developed by Stott and Quan which stresses the importance of the moisture content of the coal and the relationship between the heat necessary to evaporate this water to the heat available from coal oxidation. The work was carried out over a five month period and the emphasis is on demonstrating the effects of moisture transfer and confirming the theory of Stott and Quan.

Jan 1, 1980

Antitrust Investigation Dropped. - The Department of Justice announced that it was dropping its 5-year investigation of the aluminum industry. The investigation was over whether the aluminum companies were acting as if they were a shared monopoly. Deep Seabed Mining. - The Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) has established an Office of Ocean Minerals and Energy which will be responsible for implementing the Deep Seabed Nard Minerals and Energy Act and the Ocean Thermal Energy Conversion Act. It will establish licensing and regulatory programs.

Jan 1, 1980

Duties on Lead Imports from Mexico. - On September 15, the President signed Proclamation 4792 suspending concessions formerly granted as of January 1 on red lead imported from Mexico. The Proclamation also increased the duty payable on litharge imported from Mexico from 3% ad valorem to 3.5% ad valorem, effective September 15. Appeal of Lead Standards. - The U.S. Court of Appeals for Washington, D.C., rejected petitions by the Lead Industries Assoc. and St. Joe Minerals Corp. for a review of standards promulgated by EPA and OSHA. The Lead Industries Assoc. reportedly will appeal to the U.S. Supreme Court on the basis of the "benzene" and "cotton dust" decisions. Scheduled implementation of standards will continue during the appeal.

Jan 1, 1980

By C. P. Patel

"The Sturgeon Lake Joint Venture volcanic massive sulpide deposit was discovered in 1970. Milling was started by Falconbridge Copper Ltd. at Sturgeon Lake in September 1974. The Sturgeon Lake pit and mill are located 88 kilometers by road northeast of Ignace, Ontario. IgnE1ce is a town of some 2800 people located on the Trans-Canada Highway, 241 kilometers west-northwest of Thunder Bay. The mill is treating an average of 1100 TPD producing separate concentrates of copper, lead and zinc. Initially, difficulties were experienced in achieving accept-able concentrate grades and recoveries but these were eventually overcome. This presentation describes current metallurgical strategy as practiced at the Sturgeon Lake mill.But first, a few words about the type of ore being treated. In geological terms the ore is classified into two main categories. They are the massive sulphides with underlying zones of stringer sulphides as illustrated in Fig. 1. The plan view is shown in Fig. 2. The areas of East-limb and North-limb are as shown. These last two ores have suffered enough alteration to cause problems during treatment. The massive sulphides consist of chalcopyrite, sphalerite, galena, tetrahedrite and small amounts of pyrrhotite among other gangue materials. The stringer ore is comprised of predominantly chalcopyrite intrusions into rhyolite and has lesser amounts of sphalerite and tetrahedrite. At present we are treating a predetermined blend of massive and stringer ores from zones that have been metallurgically tested to ensure compatibility with current treatment procedure in the plant. Ore responding to this treatment is classified as normal ore while the ore proving incompatible is classified as north-limb ore or east-limb ore."

Jan 1, 1980

By John A. Kiefer

Ground fault and overcurrent protection criteria for coal mine a.c. distribution systems were examined under a Bureau of Mines funded investigation. The report begins with a literature review which discusses relaying topics including instrument transformers, ground-fault pickup methods, static relaying, and comparison of relaying techniques. A chapter on ground-fault relaying provides recommendations for maximum and minimum pickup levels as a function of maximum ground current and power system line-to-ground capacitance. Research in the area of phase overcurrent protection has resulted in a complete set of procedural recommendations for the selection and setting of overcurrent relays and current transformers, molded-case circuit breakers, and distribution system fuses in coal mine power systems. The final chapter, which discusses relay system maintenance, introduces a unique test set which was developed by KETRON and used to test the performance of relaying systems in coal mines.

Jan 1, 1980

By L. A. Neumeier

The Bureau of Mines investigated hot-rolling and forging characteristics of experimental ductile iron castings, both sand and permanent-mold, made with charges containing up to 70 pct foundry pig iron and 95 pct steelmaking pig iron. Between 1,550° and 1,950° F, most castings could be rolled to 90-pct reduction or forged to 70-pct reduction without serious cracking. Charge and composition have less bearing on workability than on subsequent properties. Permanent mold castings could be worked as readily as sand castings at 1,750° and 1,950° F. Plasticity improved with temperature. Small billets were also forged cold to 50-pct reduction without cracking. With equivalent nodularity, composition affects properties of wrought materials by altering matrix structure and strength. Properties vary with reduction and improve with increasing working temperature. Rolled material has high strength and anisotropy, and low ductility, particularly in the trans-verse direction. Annealing reduces strength and improves ductility, but anisotropy persists. At 70-pct reduction, impact resistance in the longitudinal direction is about twice that in the transverse. Annealing roughly doubles impact resistance. Deformation enhances damping capacity. The feasibility of die-forging and bar-rolling of ductile iron was evaluated in trial tests conducted under a Bureau contract. Although workability and ductility of ductile iron are inferior to those of steel, more advantage could be taken of ductile iron's plasticity to work rough shapes to final dimensions.

Jan 1, 1980

Law of the Sea. - The Ninth Session of the Law of the Sea Conference resumed July 28 at Geneva and will run for 5 weeks. The 160-nation Conference began in 1973. Two of the major factors to be discussed are the transfer of technology to the UN-controlled Enterprise or mining authority, and how the 36-member Council will make decisions. As the session completed its third week, delegates expressed little hope of completing a treaty text this year. There was a feeling, though, that substantive issues might be settled so that a treaty text can be completed next year. The Deep Seabed Hard Mineral Resources Act signed by the President on June 28, provides an interim regulatory procedure for ocean mining activities conducted by U.S. nationals that may be superseded by a law of the sea treaty.

Jan 1, 1980

Aluminum Production. -By October 1, Aluminum Company of America will restart a 35,000-ton-per-year unit at its aluminum smelter at Rockdale, Tex., restoring that facility to its full capacity of 325,000 tons annually. Primary Ingot Price Increase. -Most U.S. aluminum producers in mid-September were quoting a price of 72 cents per pound for primary aluminum ingot. On September 19, Kaiser Aluminum & Chemical Corp. announced that it would increase the price of primary aluminum ingot 4 cents to 76 cents per pound.

Jan 1, 1980

By Robert M. Baker

This document details the method whereby Allen Corporation of America gathered and analyzed data and developed an annotated bibliography of metal and nonmetal mine fire reports (1950-1979). The primary objective of this program was to develop the annotated bibliography which included MSHA accident reports and periodicals. Two additional objectives were to gather data on non-reportable fires and to conduct statistical analyses on the data to delineate trends. Data was acquired from three major areas: periodicals, MSHA fire reports, and mine safety directors. Data was separated into reportable fires (at least ½ - hour duration or injury), non-reportable fires, and opinion data. The data was then analyzed by time trends, state, ore, ignition source, burning substance, location, equipment, detection, duration, injuries, fatalities, and successful extinguishing agent. The authors make a number of recommendations: (1) improved stationary electrical equipment design and fire protection, (2) improved design of mobile equipment to separate combustibles from ignition sources, (3) improved maintenance, (4) improved housekeeping, and (5) improved training. The document is divided into two volumes and an appendix. Volume I contains data acquisition procedures, data analysis procedures, and conclusions and recommendations. Volume II contains a chronological list of mine fires and fifteen indexes to assist the reader in locating fire incident report of interest. The Appendix contains the annotated bibliography of over 300 metal and nonmetal mine fire reports and journal articles and a list of non-reportable fires.

Jan 1, 1980