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Jan 1, 1903

The State Mining Bureau of California under the direction of Fletcher Hamilton, State Mineralogist, is starting a field campaign to report on the economic minerals of California, which have an important industrial and military bearing on the present war situation. Particular interest and value attaches at the present moment to our available supplies of chrome, coal, iron, magnesite, manganese, molybdenum, quicksilver and tungsten. Trained geologists and engineers of the Bureau's staff are being sent, out to obtain information with relation to the latest developments. Advance notices will be sent to the local newspapers, from time to time, of the arrival of the engineers in the various districts. All persons interested in the minerals mentioned are earnestly urged to cooperate with the State Mining Bureau by meeting the field men while in their districts or by communicating direct with the State Mineralogist at his office in the Ferry Building, San Francisco. The State Mining Bureau has just issued Bulletin No. 72 on The Geologic Formations of California. It was written by Prof. James Perrin Smith of Stanford University, and contains a complete bibliography and resume of all of our present knowledge relative to the geological formations occurring in California. It also contains much previously unpublished data, and six tables showing geologic columns. It covers 41 pages.

Jan 6, 1917

By Stanley M. Moos

The Pueblo Viejo gold/silver mine, located in the Dominican Republic, started production in early 1974 processing ores averaging 4 g/tonne gold and 20 g/tonne silver at a rate of 7,250 tonnes/day. The ore milled is a silicified siltstone with average work index of about 8 that occurs as an extensive oxide capping of a primary sulfide orebody. The sulfide ores are refractory to conventional treatment process and extensive research work is now in progress to develop a treatment process for them. The ore deposit has a long history having been mined by the indigenous Arawak Indians (for some time in the early sixteenth century) prior to the arrival of the Spanish and then by the Spaniards. In the early 1950?s, Italian engineers attempted to process the sulfide ores. Mining by the Indians and Spanish was abandoned because of low grade and little coarse gold in the oxide ores and by the Italians because of the refractory nature of the sulfide ore. In 1969, Rosario Resources geologists discovered that there existed sufficient reserves of oxide ore for a viable mining operation and accordingly, the plant was designed, built and brought into production.

Jan 1, 1979

By Paul D. Martinka

Coal is the principal energy source for the American Electric Power System (AEP System), which generates and delivers more electric energy to its customers within a seven-state area than any other investor- owned electric public utility. The company expected to burn 21.5 million tons of coal in 1968 at its coal-fired, steam-electric generating stations. About 4.3 million tons, representing 20% of the firm's total annual requirement, was the expected yield of its captive coal mines; the other 17.2 million tons were to be purchased from commercial mines in Ohio, West Virginia, Virginia, Kentucky, Indiana, and Illinois. American Electric's largest captive coal mining operation is conducted by Central Ohio Coal Co., a subsidiary of Ohio Power Co., at the Muskingum mine in the Meigs Creek No. 9 coal field of southeastern Ohio. The mine was started in 1953 to produce the coal requirements of the Philo and Muskingum River generating plants of Ohio Power Co., and it has been supplying their annual requirements in the range of 2.5 to 3.5 million tons since that time. The Muskingum River plant is one of the major steam-electric generating stations on the AEP System. This plant began operation in 1953 with a 215-megawatt unit and now has five generating units with a total plant capacity of 1,495 megawatts. The addition of the 615-megawatt Unit 5 in the summer of 1968 increased the total annual coal requirement of the plant from 2.6 to 4.4 million tons. In order to produce the additional 1.8 million tons of coal for the Unit 5 addition and to exploit the remaining coal reserves at the Muskingum mine most economically, Central Ohio Coal Co. has undertaken a $41 million expansion and modernization program, involving the world's largest dragline and an electric railroad.

Jan 1, 1969

E. T. Dumble, Houston, Texas (communication to the Sec-retary?):—In addition to the list of publications mentioned by Mr. Schorr and those by Prof. Hofman, I call attention to the following references:— Sludi sulle Lignite, by Capacci. Turin (1890). (An excellent work.) Report of Brown Coal Industry in Germany. J. Cosmo New-berry. Department of Mines, Victoria (1892).

Jan 1, 1905

The Mammoth Mine is located some five kilometres from the town of Gunpowder which is approximately 120 km north-west of Mount Isa in Queensland.

Jan 1, 1993

By T. J. DeMull

AMAX's Sleeper Mine uses conventional cyanidation milling and heap leaching techniques to produce gold. Since milling operations commenced in March 1986, average ore processing rates have improved from the design rate of 455 tonnes per day to more than 720 tonnes per day. Heap leaching was added to the process facilities in September 1986 at a design rate of 1,500 tonnes per day, and current heap leaching rates exceed 2,680 tonnes per day. Presented are descriptions of the Sleeper processing facilities with emphasis on the crushing and grinding circuits, a review of the selection of crushing and grinding equipment, and a summary of operating performance during the first 16 months of operations.

Jan 1, 1988

Charles H. White, Harvard University, Cambridge, Mass, (communication to the Secretary*):—In answer to Mr. Jar-man's questions I am able to say that constant use (during term-time) since 1901 has shown the new appliances in our laboratory to be very satisfactory. The draft in the hoods is sufficient to lift the fumes promptly from the baths and hotplates ; and the occasional application of stove-polish,—usually about three times a year, at the recess-periods,—so well protects all iron-work in the hoods that, up to the present time, there is very little evidence of the corroding action of acid fumes. Iron should never be used in the construction of hoods above

Jan 1, 1906

The Grootegeluk coal beneficiation plant is situated near Ellisras in the Waterberg coal= field in the Transvaal, RSA. At this plant 15 million tons of coal bearing material per annum are beneficiated by means of two-stage heavy medium bath and cyclone plants. Because of the very low yield of 12 % coking coal product, run= ping costs are of the - utmost importance. For this reason extensive tests were carried out to establish the most effective crushing and bene= ficiation methods and suitable aquipment. At the second heavy medium separation stage, the near-gravity material (+ 0,1. g/cc) amounts to 45 % and daily plant performance ana=lysis is required to ensure acceptable plant efficiency. Beneficiation processes for the -0,5 mm coal originally considered were froth flotation, shaking tables, heavy medium cyclones and water- only cyclones. When the froth flotation route was decided upon, further test work was done to enable selection of the equipment most suitable for the particular requirements.

Jan 1, 1987

By F. O. Garrabrant

Power is furnished to the Climax Molybdenum Co. by the Public Service Co. of Colorado over two 100,000-volt lines to a bank of three 3333-kva. transformers 100/13.8 kv. These transformers are so designed that with the addition of forced cooling their capacity may be increased 33? per cent at 12,000-ft. altitude. Under present conditions, these transformers are operated at 140 Per cent of their rating with forced air cooling. On the secondary side of this bank there is a 15-kv., 1200-amp. Westinghouse oil circuit breaker provided with automatic reclosing relays allowing three successive short circuits before lockout. From this breaker 13.8-kv. power is transmitted to a central switching station (Fig. I) where all circuits radiate to the different operations of the property. Each circuit is protected by a 23-kv., 600-amp. oil circuit breaker with by-pass and isolating disconnecting switches. Mine Power at 13.8 kv. enters the mine through a ventilation raise over a three-conductor, size 1-0 varnished cambric insulated, leaded, steel-wire armored cable, insulated from 17 kv. This power is received and distributed through one switching station and four underground substations, shown in Fig. 2. No. 370 substation (Fig. 3) contains three a 13,800/440-volt, single- phase Pyranol transformers protected on the high-voltage side by a 600-amp. manually operated oil circuit breaker. This station serves 20 slusher-hoist motors, a 45-kw., three-phase, 220-volt electric furnace, a Massco hot miller for tempering and milling Timken detachable bits and a hoist with 175-hp motor on the No, 3 development shaft. Also at this shaft are three pumps. One two-stage pump, 1200 gal, per min., 500-ft. head, 3600 r.p.m., driven by a 150-hp. motor, is at the bottom of the shaft, Two deep-well pumps, 500 gal. per min., 500-ft. head, are at the collar of the shaft. under normal operation the one pumping 1200 gal. per min, is controlled by a float switch to take care of the water. If this pump fails, or if its capacity is insufficient, the first 500-gal. pump is automatically started1 and if still more capacity is needed the second 500-gal. pump automatically starts. Time delay relays are provided on the deep-well pumps, so that if power fails the column will have time to drain before the Pumps restart. On failure of any Of these, an alarm is sounded in the train dispatcher's office, so that mechanics can be sent to ascertain the cause of failure and make repairs. The cable from No. 37' substation is run to the switching station, in which are four 15-kv., 600-amp. direct-current sole-noid-operated oil circuit breakers. The current for Operating and tripping is furnished by a 125-volt storage battery. All breakers are operated from the switchboard in the compressor room. One circuit from this switching station goes to the

Jan 1, 1946

By Harper F

This paper outlines the authors' views of the methodologies which can be employed to value mineral properties at different stages of development for the purposes of project financing, mergers and public floats. This paper discusses the key issues in Discounted Cash Flow (DCF) analysis including the importance of data verification and the shortcomings in DCF analysis. Stockmarket valuation measures and valuation methodology for exploration and pre development projects are examined through examples and pitfalls are identified. The use of valuations in corporate transactions and their strategic value is also discussed.

Jan 1, 1994

R. V. NorHis, Wilkes-Barre, Pa. (communication to the Secretary*) : The electric-haulage plant of the Short Mountain Colliery of the Lykens Valley Coal Co., mentioned by Messrs. Stoek and Harris as the earliest underground electric plant in the United States (and, I believe, the second in the world), was started July 23, 1887. The plant, designed by W. M. Schlessinger, consists of two motor-cars, each weighing about 5 tons and equipped with a 32-h.p. Union Electric Go. motor. The original general construction of the motor-cars is shown by Mr. Stoek; but they were rebuilt, the same year, with some important improvements in design; and, except for strengthening the frames and replacing the original pig-iron weights by a casting, they have not been greatly changed since that time. The generating-plant consists of two Union Electric Co. dynamos of 65-h.p. each, driven by an old 18- by 48-in. plain slide-valve engine; the ordinary voltage is 450 and the amperage varies from 40 to 200; the average indicated h.p. of the engine is about 75, with a steam-consumption of about 75 lb. per i.h.p. per hour; and as the cost of steam at this colliery is 8.11 cents per 1,000 lb.,the steam-cost per day is about $4.56.

Jan 1, 1904

By Thomas A. Wheeler

The reagents commercially used in coal flotation and their roles are reviewed and discussed According to their function the reagents are divided into often overlapping groups: 1. Collectors 2. Frothers 3. Conditioning Reagents Frothers have by far the largest effect on the amount of coal recovered They act not only in their traditionally accepted function of “bubble makers”, but in coal flotation they serve in a seldom acknowledged role of collectors. A lab flotation study on four samples of different coal ranks shows how these react to various frother families and proves that no froher is the optimum reagent for all types of coal. The advent of new technology in flotation equipment in the past decade has resulted in various novel designs of column cells, Jameson and Centrifloat™ cells, air-sped hydrocylones, etc. All should require special frothers or blends of frothers to meet their specific needs.

Jan 1, 1994

By Dan Brown

Improvements in construction equipment and techniques in recent years have made possible the use of drilled shaft foundations in diameters and lengths not previously considered practical or feasible. Many highway bridge and other structures are now routinely founded on drilled shafts which are 2.5 m to 3.0 m (8 to 12 feet) in diameter and extending over 60 m (200 feet) in depth below grade. There are unique challenges associated with constructing such large and deep cast-in-place foundations and engineers should be aware of the special needs associated with site investigation, construction specifications, material requirements, and quality assurance. This paper outlines a number of special considerations for these foundations, along with strategies that may be employed to improve the reliability and quality of large drilled shaft foundations.

Jan 1, 2008

The appraisal of mineral reserves by a lender is carried out at the initial stages in developing a loan for a mine. The depth of investigations is influenced by the competence of the explorer, the type of commodity and knowledge of the geological environment. The lender looks for a reserve life which exceeds the term of the loan plus contingencies for events such as cost over-runs, adverse markets and production difficulties. The physical features of importance are discussed. Factors with direct financial implications are considered for their incorp- oration in sensitivity analyses to allow risk appraisal. When satisfied, the lender can then proceed to review cash flow forecasts, the basic strength of the project, then determine with the borrower the components and alternat- ives of a loan package.

Jan 1, 1979

By T. Y. Chong, J. A. Folinsbee, M. Fullam

PJV Dome Mine has used some form of gravity concentration since start of milling operation in 1909 to recover free milling gold. Amalgamation and conventional jigs were first used and were replaced with the Knelson Concentrators in 1993. The Knelson concentrates produced were upgraded on a conventional shaking table prior to smelting and refining into gold bullion. In May 2002, a comprehensive review of the latest gravity recovery technology led to a piloting campaign aimed at further improving gravity recovery. The Knelson concentrates, subjected to intensive cyanide leaching in an Acacia pilot plant, were found to be amenable to intensive cyanide leaching with over 98% of the gold being dissolved within 24 hours. An Acacia Intensive Leach Reactor was successfully installed and commissioned in December 2002, to replace the shaking table. his paper describes pilot scale testing, installation, commissioning and optimization of the Acacia Intensive Leach Reactor. Also, the economic impacts on down stream processes are highlighted.

Jan 1, 2005

By Jack E. Bailey

From a start in 1957, milling 3,000 TPD of copper ore, the Cyprus Pima Mining Company, which is located 20 miles south of Tucson, has expanded its operations four times, and is currently treating over 55,000 TPD of ore.1 The most recent expansion added a 14,000 TPD semi-autogenous concentrator to the operation. Shortly after startup in January, 1972, the semi -autogenous plant exceeded the designed tonnage rate.2 Ore from the mine is delivered to a 54 inch gyratory crusher and is reduced to a minus 8 inch product. From the crusher the ore is stacked on a surge pile and then reclaimed and fed to the two parallel grinding circuits. A 28 ft. diameter by 12 ft. long semi-autogenous mill and a 16.5 ft. diameter by 19 ft. long ball mill make up each grinding circuit. The semi-autogenous mills are in closed circuit with screens and the ball mill circuits are closed with hydro- cyclones. Rougher flotation follows the grinding operation. Concentrate regrinding and cleaner flotation is performed in Mill I, the older mill. The generalized flowsheet is shown in Figure 1.

Jan 1, 1975

By Don Berger

Highwall scaling, bolting and technical blasting are important aspects in the remediation of existing highwall exposures. Proper planning, design and research are important first steps in the development of long term stability. Research into old workings and their influence on highwall stability control the planning and design. These steps are followed by improvements in blasting techniques, highwall monitoring programs and constant evaluation of the results. Recently, due to a number of factors, the highwalls of the Open Cut Mine have started to deteriorate, creating both operational and potential safety problems. Geologic setting, highwall design, mining operations, old workings and weather have combined to create adverse conditions that have allowed sections of the highwalls to become unstable. Homestake Mining Company has developed a program to alleviate the existing ground control problems and to decrease the effect operations has on future highwall stability.

Jan 1, 1996

By John J. Laffin

"Nova Scotia Department of Mines and Energy Throughout the history of Nova Scotia, trends in the production and use of its coal resources have resulted in major impacts on the economy and society of the province. Current trends in coal demand locally, nationally and internationally are having and will have an increasing positive effect on Nova Scotia over the next twenty years-in terms of energy supply, job creation and general economic development. Coal for electrical generation is an immediate and key objective of Nova Scotia's energy plan; and, in the long term, coal-derived fuels will meet the province's needs for transportation fuels. Demand for metallurgical coal is also expected to increase, especially if the merchant coke plant currently under investigation becomes a reality.Meeting these coal supply and utilization objectives in the face of increasing environmental, social and economic constraints poses a tremendous technical challenge. Work has begun on projects to expand coal production capacity and to adapt new technologies for coal preparation and utilization to the specific needs of Nova Scotia; much more work will be required in the coming decade in order to succesfully tap this resource.IntroductionThe energy problem facing Atlantic Canada has a few unique features not found in the rest of the country. Canada, as a whole, has access to a diverse mix of energy resources, including crude oil, natural gas, coal, hydro and uranium, with the result that crude oil supplies only about 40 per cent of Canada's primary demand. In contrast, foreign crude oil dominates Atlantic Canada's energy mix, supplying over 70 per cent of the primary energy demand.This results in important differences in various sectors. Nationally, about 5 per cent of the electricity is generated from oil whereas last year in Nova Scotia approximately 40 per cent of the electricity generated was from imported oil. Residential, commercial and industrial space heating, and industrial process heating in Atlantic Canada was almost 100 percent dependent on foreign oil. This is in sharp contrast to the situation in central and western Canada, which have access to secure domestic natural gas, oil and hydro electricity."

Jan 1, 1982

By Lionel A. York

This paper outlines the type of water-bearing formations encountered in the Prairie Sediments and describes a method for effectively sealing these zones in order that shaft-sinking operations may be carried out with safety. Details are given of the procedure for carrying probe holes ahead of the shaft bottom. These probe or grout holes are employed for establishing a series of overlapping grout covers around the proposed shaft excavation to safeguard against large inflows of water during sinking. The pattern and length of grout covers cannot be standardized, and each cover needs to be specially designed to suit the varying ground conditions. In order to provide effective protection through the Prairie Sediments, the number of holes in any one cover would not be less than 8, and possibly as many as 64 would be required in certain zones. The length of covers would vary from 100 ft. to 250 ft. Emphasis is placed on the need for obtaining accurate geological and water information from exploratory holes, drilled in the shaft vicinity, in order to effectively plan all grout covers.

Jan 1, 1964