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By Frédéric Rocher-Lacoste

On July 2nd, 2007, LCPC and LOADTEST performed a static loading test with an Osterberg-cell on a bored pile of 1600 mm diameter. The 56.50 meters deep test pile constructed by Trevi Spa for Soares da Costa group, was near the Cacheu river in Guinea Bissau. This test was conducted to validate the design of the foundations of the Sao Vicente bridge; a project undertaken by the Ministry of Public Works of the Republic of Guinea Bissau and funded by the European Development Fund. Sub-surface conditions at the test pile location consist primarily of layers of weak sands and clays. The piles were loaded statically using the O-cell® bi-directional method 25 days after concreting. The maximum sustained bi-directional load applied to the pile was 11.7 MN. At the maximum load, the displacements above and below the O-cell assembly were 6.6 mm and 81.9 mm, respectively. The resulting pile head behavior has been calculated for a combined skin friction and end-bearing load of 29.3 MN. The piles were also instrumented using LCPC removable extensometers, which made it possible to measure the mobilization of shaft friction and toe resistance. The adjusted test data indicated that this pile would settle approximately 12.2 mm for the service load of 12MN applied at the head of the pile. This paper provides a very brief presentation of the bridge project and the test pile instrumentation: LCPC removable extensometers and O-cell® instrumentation. The results are detailed and analyzed herein and the combined use of these two instrumentation systems is a world première.

Jan 1, 2008

By D. H. Newland

New York has a small but not insignificant place in the oil and natural gas industries of the United States. It has had a continuous record as an oil producer since 1872, with an aggregate yield of about 104,000,000 bbl. The reported output for 1935 was 4,237,000 bbl., a gain of more than 10 per cent for the year and a total that has been exceeded only in the early period of flush production half a century ago. The industry has been steadily building up since 1920 with the successful practice of the water drive, which has given a new lease of life to pools that had been practically drained of oil recoverable by pumping. An additional output of 2000 bbl. or more per acre is being procured by this method. Altogether the fields in New York State cover about 55,000 acres. Their limits are well defined and it is unlikely that they will be extended in the future, although there is some prospect of finding additional supplies by deeper drilling. The oil from New York is all classed as Pennsylvania grade, for which the recent price has been about $2.50 a barrel. It is refined at Olean, Wellsville and Bolivar, in the oil district, and partly in Pennsylvania refineries. Exploration for natural gas, outside of the established districts, was considerable during the year. Altogether 59 wells were drilled, distributed over 13 counties, of which 33 were listed as producers and 26 were dry. At the close of the year, 13 wells were in process of drilling. The 33 producing wells had a combined estimated flow of 278 million cubic feet per day. The best results were obtained from exploration in Allegany County, where out of eight wells drilled to the Oriskany sandstone five were successful and showed a combined open-flow capacity of 107 million cubic feet. The Oriskany sandstone was encountered at a depth of 4500 to 4900 ft. In Steuben County, next east of Allegany County, two out of seven wells to the Oriskany proved productive, and one of these, in the town of Greenwood, on the Watkins structure, was probably the largest that has so far been opened in the state, with a reported yield of 35 million a day. In the central part of New York interest was awakened by the activity shown in exploring for gas in the Trenton limestone, in Camden, Florence and Rome townships, Oneida

Jan 1, 1936

By D. H. Newland

New York has a small but not insignificant place in the oil and natural gas industries of the United States. It has had a continuous record as an oil producer since 1872, with an aggregate yield of about 104,000,000 bbl. The reported output for 1935 was 4,237,000 bbl., a gain of more than 10 per cent for the year and a total that has been exceeded only in the early period of flush production half a century ago. The industry has been steadily building up since 1920 with the successful practice of the water drive, which has given a new lease of life to pools that had been practically drained of oil recoverable by pumping. An additional output of 2000 bbl. or more per acre is being procured by this method. Altogether the fields in New York State cover about 55,000 acres. Their limits are well defined and it is unlikely that they will be extended in the future, although there is some prospect of finding additional supplies by deeper drilling. The oil from New York is all classed as Pennsylvania grade, for which the recent price has been about $2.50 a barrel. It is refined at Olean, Wellsville and Bolivar, in the oil district, and partly in Pennsylvania refineries. Exploration for natural gas, outside of the established districts, was considerable during the year. Altogether 59 wells were drilled, distributed over 13 counties, of which 33 were listed as producers and 26 were dry. At the close of the year, 13 wells were in process of drilling. The 33 producing wells had a combined estimated flow of 278 million cubic feet per day. The best results were obtained from exploration in Allegany County, where out of eight wells drilled to the Oriskany sandstone five were successful and showed a combined open-flow capacity of 107 million cubic feet. The Oriskany sandstone was encountered at a depth of 4500 to 4900 ft. In Steuben County, next east of Allegany County, two out of seven wells to the Oriskany proved productive, and one of these, in the town of Greenwood, on the Watkins structure, was probably the largest that has so far been opened in the state, with a reported yield of 35 million a day. In the central part of New York interest was awakened by the activity shown in exploring for gas in the Trenton limestone, in Camden, Florence and Rome townships, Oneida

Jan 1, 1936

By J. H. Jacobs

In late 1946, research was begun at the Bureau of Mines Electrometallurgical Laboratory at Boulder City, Nev., to determine the possibility of electrowinning manganese from chloride electrolytes on a continuous basis. All phases of electrodeposition were investigated on a small scale it the laboratory, and the results were reported by Jacobs and Churchward. These results indicated that a chloride process had certain possible advantages over the sulfate process that made it worthwhile to continue the investigation on a semi-pilot-plant basis, and this paper reports the results of this work. Research and development work on a process for electrowinning manganese from low-grade ores has been carried on intermittently by the Bureau of Mines since 1936. A process was developed, using sulfate electrolyte, that has been extensively described in the literature.

Jan 1, 1951

1. A total of 14,413 mining operations reported employment to the Mine Safety and Health Administration (MSHA). Nearly half (48.9%) were sand and gravel operations, followed by stone (28.5%), coal (14.7%), nonmetal (5.7%), and metal mines (2.1%). 2. Mine operators reported 240,000 full-time equivalent workers1 (down 3.9% from 1999). Independent contractors reported 42,000 full-time equivalent workers working on mine property (up 8.6% from 1999). Coal operators accounted for 26.8% of reported employee hours, followed by stone operators (25.9%) and sand and gravel operators (12.1%). 3. Eighty-four (84) work-related mine fatalities occurred in 2000 compared to 90 the year before. •The mine fatality rate was 29.8 per 100,000 full-time equivalent workers compared to a fatality rate of4.6 per 100,000 employees for all private industry. •Thirty-one percent (31%) of the fatalities occurred in underground work areas, which account for only17% of total employment. •Although the largest number of fatalities (28) occurred among miners who work for coal operators, coal contractor employees had the highest fatality rate (61.1 per 100,000 full-time equivalent workers). 4.There were 10,839 nonfatal lost-time injuries reported to MSHA, occurring at a rate of 3.8 injuries per 100full-time equivalent workers, and resulting in a total of 417,918 lost workdays.2 •Among all employees,3 the highest injury rate occurred among coal operator employees (5.6 nonfatal injuries per 100 full-time equivalent workers). •The highest percentage (34.7%) of nonfatal lost-time injuries were due to handling materials (e.g., over-exertion in lifting, pulling, or pushing objects), which also accounted for the greatest percentage of lost workdays (29.3%). •Among the most frequently occurring injuries, the most severe (as measured by the median number of days lost) were associated with accidents involving falls of ground, the use of powered haulage, and slips or falls. •The most frequently reported part of the body injured was the back (22.9% of all injuries). Back injuries accounted for the highest percentage of lost workdays (21.6%). 5.Seven hundred sixty-seven (767) cases of occupational illness were reported to MSHA. •The most frequently reported illness was repetitive trauma, resulting in joint, tendon, or muscle inflammation or irritation (37.3%). •There were 155 (20.2%) illnesses reported as hearing loss. The majority (68.4%) of hearing loss cases occurred among surface workers. •Coal workers' pneumoconiosis accounted for 14.5% of reported illnesses.

May 15, 2002

By Charles Prasky

The Bureau of Mines investigated the conversion of nonmagnetic iron minerals to magnetic form through reduction Toasting operations. The primary objective was to obtain a concentrate that could be used as a direct shipping material for blast furnace consumption. Crude iron materials from the Steep Rock Lakes, Ontario, area were prepared into a blend of 8 parts siliceous ore, 3 parts pyritic ore, and 1 part tailings. Experimental work included laboratory reduction roasting tests, two continuous 10-day campaigns, and one 12-hour test all in a 34-inch by 36¬-foot rotary kiln. The objective of the project was achieved in producing an iron concentrate containing about 66 percent iron with over 90 percent iron recovery. Desirable operating conditions were developed in the kiln but optimum process variables were not completely established.

Jan 1, 1969

By Forrest T. Moyer

THIS CHAPTER of the Minerals Yearbook (Volume III) contains overall injury experience for coal mines, both anthracite and bituminous coal, coke plants, petroleum and natural gas, peat, and asphalt and related bitumens (native); metal mines, metallurgical plants, including ore-dressing plants and primary nonferrous reduction plants and refineries; nonmetal mines; nonmetal mills; sand and gravel operations; slag (iron blast-furnace) plants; and stone quarries and their related plants. Volume I of the yearbook contains a chapter showing injury experience and employment data treated separately by categories: Metal mines, nonmetal mines, quarries and their related plants, metallurgical plants (ore-dressing plants and primary nonferrous reduction plants and refineries are shown separately), nonmetal mills, sand and gravel plants, and iron blast-furnace slag plants. Volume II contains injury and employment experience in the fuel industries (anthracite, bituminous coal including lignite, coke, petroleum and natural gas, native asphalt and related bitumens, and peat). Injury and employment data were collected from coal producers on the regular mandatory basis as required by the Federal Coal Mine Safety Act (30 U.S.C., sec. 455). Similar data for 1962 from metal, nonmetal (except well and brine operations), stone, and sand and gravel producers were collected by a. mandatory reporting system under the provisions of the Act of September 26, 1961, Public Law 87-300 (75 Stat. 649). Before 1962, these nonfuel producers reported voluntarily to the Bureau of Mines. Producers of all other minerals (fuel and nonfuel) reported the requested injury and employment data voluntarily to the Bureau for 1962, the same as in preceding years.

Jan 1, 1963

By M. F. Goodrich

The concept of using water-only cyclones as a clean coal scalping device preceding a heavy media cyclone circuit shows considerable promise, as it can considerably reduce the feed to the heavy media cyclone circuit. The system will not perform as well as a heavy media cyclone circuit alone, but the resultant loss in yield is small and may be negligible under some conditions. The concept of water-only cyclone scalping has previously been suggested by others. By reducing the amount of raw coal to be processed in the more expensive circuits overall capital and operating costs may be reduced. There are a few commercial plants with circuits operating on this concept. In the Warwick and Rowland plants water-only cyclones are used to scalp the feed to a heavy media vessel and Deister tables respectively while Amherst Coal Company's McGregor plant uses them to scalp the feed to a heavy media cyclone circuit. The system was evaluated on a technical basis, both from a theoretical viewpoint and by analysis of a computer simulation, in order to gain a fuller understanding of its usefulness and limitations.

Jan 1, 1977

By O. C. Blade

The use of Diesel fuel continues to increase. In the United States during 1951 over 120,000,000 barrels of Diesel fuel oil were sold. The railroads used approximately 43.5 percent of this volume; industries such as smelters, mines, and manufacturing plants used about 12 percent; trucks, busses, tractors and bulldozers 20 percent; water craft 14.5 percent; and the remaining 10 percent was consumed by gas and electric utilities, the military forces, and oil companies. These figures were calculated from data issued by the Bureau of Mines. 2/ Complete data for 1952 are not yet available, but it is known that by December 1952 over 13 3/4 million barrels of Diesel fuel per month were produced by the country's refineries and by April 1953 the monthly production had increased to 1 4,333,000 barrels.3/ Information on the properties of this type of engine fuel is very important to the petroleum industry, engine manufacturers, and consumers. To supply this information the American Petroleum Institute and the Bureau of Mines, United States Department of the Interior, under cooperative agreement, are conducting annual surveys of Diesel fuel oil produced in refineries in this country.

Jan 1, 1953

By C. J. Wilhelm

The disposal of brines produced with crude petroleum and natural gas has been a long-continuing problem to oil and gas operators as well as to farmers and stock-raisers in the vicinity of producing fields. An impartial appraisal of conditions pertaining to the problem of brine disposal leads to the conclusion that study of the technical consideration, with proper weight given to the economic and social factors, is the most desirable approach to this problem. Brine disposal is a problem of such magnitude in certain areas in the State of Kansas that in August 1934 a cooperative agreement was made between the Kansas State Board of Health and the U. S. Bureau of Mines for a cooperative technical study of methods of brine disposal.

Jan 1, 1935

By E. H. Cho

A current environmental concern is the cleanup and restoration of soil contaminated with low-level radionuclides at DOE sites including the Nevada Test Site. At the present, there is no applicable process to economically and effectively deal with the remediation of contaminated soils. This situation requires development of a selective flotation process to separate the radionuclides from contaminated soil efficiently and economically. In this study, a minus 200 mesh size fraction of pure cerium dioxide was used as a surrogate for plutonium oxide which is the major contaminant at the Nevada Test Site. A Hallimond flotation cell was utilized to examine the flotation behavior of cerium dioxide with oleic acid under various conditions of pH and collector concentration Mechanical cell tests were conducted to float the surrogate from a mixture with uncontaminated Nevada Test Site soil in the absence and presence of calcium carbonate as a carrier. Two different sizes of the carrier (minus 150 mesh and 65-150 mesh) were tested. It was found through the Hallimond cell flotation tests that the cerium dioxide could be floated well at pH's 4 and 9 with 10-3 molar oleic acid. It was also found that the addition of the carrier drastically enhanced the flotation recovery of cerium dioxide. The flotation recovery of the surrogate increased from 34 % to 65 % by adding only 0.5 % calcium carbonate (minus 150 mesh) in the feed and also increased to 95 % by adding 10 % of this carrier to the feed. The finer size fraction of calcium carbonate (minus 150 mesh) was more effective in recovering cerium dioxide than the coarser size fraction (65-150 mesh) The flotation method utilizing a carrier of calcium carbonate seems to provide a high potential to be used for the remediation of soil contaminated with radionuclides at various Department of Energy's nuclear weapon sites.

Jan 1, 1996

By Washington Luiz Mafra

Every year the conventional direct reduction processes ? Midrex and HYL III ? increased their market share in the world steel production, even though they are only economically feasible in countries where natural gas is available at competitive prices. In this context, the new Midrex projects are based on large reactors (Megamod - 1.5 to 1.8 Mt/y of DRI), reduction temperatures of the metallic burden up to 850oC, with bustle gas temperatures between 960oC e 1050oC. Thus, the requirements of metallic burden performance, as well as the evaluating methods, usually based on ISO standards, need to be reviewed. It is well known that the standards usually applied to quality evaluation do not reflect the performance of metallic burden inside the reactors. This paper describes the different methods of evaluating the disintegration under reduction of DR pellets based on ISO 11257 standard. This is the most important method used by pellet producers and customers for evaluating DR feedstocks. The different methodologies tested to evaluate the disintegration under reduction had varying results, evidencing the relevance of the method and the quality of the pellet. Nevertheless, validating the method in an industrial reactor is still fundamental.

May 1, 2007

During the period 1979 thru 1982, Multi Mineral Corporation conducted a mining I research program at the United States Department of the Interior's Bureau of Mines Oil Shale Mining Environmental Research Facility in the Central Piceance Creek Basin, Rio Blanco County, Colorado. The program consisted of mining, environmental and geotechnical research data and, the results are described in this report.

Jan 1, 1983

By Milan Terčelj, Matej Drobne, Urška Klančnik, Peter Fajfar

The study of oxidation behavior of High Chromium Steel material used for surface layer of work rolls was carried out. Specimens taken directly from the roll were subjected to thermal fatigue in the temperature range between room temperature and 500 °C up to 700 °C by using thermo-mechanical simulator Gleeble 1500D. Our observation was focused on the impact of oxidation as a principal mechanism of degradation of the roll’s surface layer - mainly on the characteristics of oxidation propagation in relation to the test temperature and microstructure constituents characteristics of the material. Oxidation is considerably accelerated by certain characteristics of eutectic and primary carbides, i.e. their size (area), composition, morphology, orientation regarding to the water-cooled surface, etc. In the presented paper selected cases where emphasized oxidation takes place are investigated, analyzed and explained. Obtained results thus represent a contribution to explanation of conditions which lead to acceleration of oxidation behavior that in turn can lead to chipping or even early spalling of material from the roll surface layer.

Oct 1, 2019

By Marlies Grimmer, Frank Amo Boateng

One of the challenges of mining is the concentration of heavy metals it releases into the environment through a phenomenon called Acid Mine Drainage. Freiberg is no exception due to its long mining activities. The European Union proposes that all rivers and streams must be in a good ecological status by the year 2027 but this would be difficult for large water sources as it would be economically unviable. Consequently, the approach of treating these waters at point sources would be of immense help and hence this column experiment on mine water treatment with carbon sorbents to remove zinc form the Rothschönberger Stolln. For this experiment three resins namely, APTsorb, activated coke, charred fermentation residues (which was produced by the Freiberg University of Mining and Technology) were analyzed through a simple column experiment to determine their sorption capacities. Through their sorption capacity as this experiment seeks to ascertain: we are able to make suggestions scientifically on the best material among the three for the future design of a treatment plant for the RSS. After the experiment whereby a 10 ml peri glass column was used, material A: APTsorb showed the least adsorption capacity (0.01 meq/g) and this could be attributed to the fact that the resin works well under pre-determined parameters such as pH and surface area. Material B: Activated coke showed a better sorption capacity (0.53 meq/g) in comparison to the basis value used for this experiment. Material C: charred fermentation residue which was produced by the University showed the most efficient capacity of (1.69 meq/g). This in comparison with the value used as the basis for this experiment showed that material C (charred fermentation residue) is very efficient for zinc sorption. pH values measured at the effluent of all the experiment were slightly higher than the pH measured in the initiating water.

Feb 1, 2024

By C. J. Wilhelm

The disposal of brines produced with crude petroleum and natural gas has been a long-continuing problem to oil and gas operators as well as to farmers and stock-raisers in the vicinity of producing fields. .An impartial appraisal of conditions pertaining to the problem of brine disposal lead to the conclusion that study of the technical considerations, with proper weight given to the economic and social factors, is the most desirable approach to this problem . Brine disposal is a problem of such magnitude 1n certain areas in the State of Kansas that in August 1934 a cooperative agreement w s made between the Kansas State Board of Health and the U. S. Bureau of Mines for a cooperative technical study of methods of brine disposal.

Jan 1, 1935

By W. D. Elston, A. E. McLaughlin, G. B. Hampton, W. L. Barham, J. F. Murphy, W. H. Cundiff, J. W. Mulloy, R. G. Breuer, J. W. Shaffer

Introduction Alumina (aluminum oxide) is the material from which all the world's aluminum is produced. In the Western World, all the alumina is made from bauxite by the Bayer process. In the nearly 150 years since aluminum was first isolated by Oersted, the metal has grown from a laboratory curiosity to a position of major importance in the world's commerce. In terms of annual production rates aluminum is first among nonferrous metals. Oersted's discovery-reduction of aluminum chloride with potas¬sium amalgam-was improved on by Ste. Claire Deville, whose so¬dium amalgam reduction of aluminum chloride led to the commercial production of aluminum in France in 1855. Ste. Claire Deville's method prevailed until 1886 when Charles Martin Hall and Paul T. Heroult each invented a process for the production of aluminum by the electrolysis of alumina dissolved in molten cryolite. The inven¬tion by Karl Josef Bayer in 1888 of an economical process for making very pure aluminum oxide (alumina) from bauxite established the necessary link between known ores and the Hall-Heroult reduction process. Bayer's work completed the scientific base-the ore bauxite refined to alumina by the Bayer process (U.S. Patent No. 515,895), the alumina reduced to aluminum in the Hall-Heroult cell (U.S. Patent No. 400,766--upon which today's aluminum industry is founded. Small-scale production of aluminum in the U.S. began in 1888 utilizing the Hall cell. By 1903, bauxite properties and a Bayer process refining step had been incorporated into the production activities. On this base the aluminum industry in the U.S. has grown at an annual compounded rate of 15%. Since 1946 the annual growth rate has been 10%.1 The rapid growth of the industry is the result of many factors among which are the existence of widespread bauxite ore deposits; a sound and economic production technology; and the properties of the metal-lightness, strength, ductility, good electrical and heat con¬ductivity, and pleasing appearance, which lead to ever greater de¬mands for aluminum in an industrializing society. At the inception of the industry, the only market that could be found for aluminum was in the production of cooking utensils. How¬ ever, the rapidly accelerating industrial and technological development of the Western World soon created new needs for aluminum, and today aluminum is marketed in a broad range of industrial, commer¬cial, and consumer applications. The principal uses for aluminum are:' building and construction, 22%; transportation, 18%; electrical, 13%; packaging, 11%; consumer durables, 10%; machinery and equipment, 7%; other, 19%. The 1974 production of primary alumi¬num in the world was 14.5 million short tons, which at an approximate ingot price of 40¢ per lb puts a value of $11.6 billion on the industry product prior to fabrication. While aluminum is widely distributed in the earth's crust and is a major constituent of many rocks and soils, to date no method of extraction of aluminum from such nonbauxite material has been brought to commercial practice in the Western World. In the USSR alumina is produced by the complex processing of nepheline syenite, but elsewhere all commercial production of alumina is from bauxite. A brief discussion of recent developments and other processes for alumina is included in the subsection "Other Processes for Alumina," page 19-15. In early 1973, a major U.S. aluminum producer announced the successful development of processes for the production of aluminum from aluminum chloride. This achievement promises to exert a major influence on the future of the aluminum industry. In the initial com¬mercial application of this new technology, Bayer alumina will be chlorinated, and the aluminum chloride then reduced by electrolysis. Important claims for the new processes are lower energy requirements (one-third less than obtainable in Hall cells) and reduced labor costs. Capital costs are said to be no greater than for conventional plants. While the announced intention is to produce the aluminum chlo¬ride from Bayer process alumina, the new chloride reduction process will eliminate the other raw materials, carbon and fluorides, required by the conventional Hall cells. The electrodes in the chloride cell will not be consumed on the reduction process and the electrolyte will have, as the name indicates, a chloride rather than a fluoride base. 2. Bauxite Definition and Origin. Bauxite is a naturally occurring raw material composed principally of a mixture of one or more of the hy¬drated aluminum oxide minerals gibbsite (Al2O2 3H2O), boehmite (Al2O3 H2O), and diaspore (Al2O, - H2O), and impurities of silica, iron oxide, titania, and other various elements in trace amounts. It is an end or near-end product of chemical weathering. Depending on the amount of iron impurities, the color of bauxite varies from dark red and brown to pink to white. Some bauxite is finely divided, free digging earthy material, while other forms are dense and rocky, requiring explosives in mining. Many gradational forms exist. It is one of the most variable of mineral raw materials in chemical composition and physical appearance. It is generally believed that bauxite deposits resulted from intense chemical weathering of aluminum-bearing rocks or formations under tropical or subtropical conditions with alternating wet and dry sea¬sons. Topographic conditions were favorable for drainage and the in-situ accumulation of aluminum, iron, and titanium oxides. There was low to moderate topographic relief with a minimum of erosion during long quiet periods in earth history.2 The occurrence of bauxite is widespread and it has been found on all continents except Antarctica. Production was reported from 27 countries in 1974, at which time total world production was over 79 million metric tons. Of this production 76% was from seven coun¬tries-Australia, Jamaica, Surinam, Guinea, USSR, Guyana, and Greece-which ranked in that order of production. In Table 1 are shown typical compositions of bauxite from some

Jan 1, 1985

By G. A. Vissac

In this paper we intend to deal particularly with the economic side of coal washing as it applies to our mines. We will then discuss why the dry-cleaning process has been selected, and give a brief description of our plant, dwelling only on its specific features and referring the reader to the numerous papers published on the subject for any details on the principles and machinery used in dry cleaning. ECONOMIC DISCUSSION The washery introduces an extra cost for depreciation, operation, and loss in treatment. A certain proportion of the coal, now being sold, and which the miners have been paid for. will have to be wasted. As a whole, the total increase in cost would be approximately 60 cents per ton. On the possibility of recovering this amount depends the success of the washery. There are two advantages to be expected from the washery, the first, which occurs at the mine and which will be certain; the second, more difficult to estimate, because it depends upon convincing our customers that they should pay more for a better product.

Jan 1, 1924

By T. T. Chen

Canadian Electrolytic Zinc has developed the "cement-stabilization of jarosite residue" Garofix) process to stabilize zinc plant jarosite residues for disposal. The cement-jarosite mixtures cure quickly, have good mechanical strength and low hydraulic permeability; they possess good neutralizing capability and chemical stability. In the jarofix process, Portland cement partly decomposes jarosite to form (SO4MOH)12.nH2O, ferric hydroxide and an alkali sulphate. Approximately 40% of the jarosite reacts in mixtures containing 30% cement. The jarofix product also contains various Ca-Al-Fesilicate-sulphate-hydrate phases and gypsum, which bond the individual particles together imparting mechanical strength and reducing the permeability. Most of the reactions take place in the first few hours of curing. Ammonium jarosite is slightly more reactive than sodium jarosite but releases NH3 gas; water-soluble Zn in the jarosite residue is stabilized in the cement reaction products.

Jan 1, 1996

By Chas Fettke

DURING the summer of 1916, while on a visit to the United States Agricultural Experiment Station at Mayaguez, Porto Rico, the writers were told by D. W. May, the director, that an occurrence of manganese ore had been reported from the mesa southeast of Mayaguez. A visit to the locality showed that the mesa is covered by a mantle of bright red soil resting upon serpentine. Here and there over its surface concretionary masses of limonite have been washed out of this soil. These were FIG. I.-MAYAGUEZ FROM NORTHWEST END OF MESA. apparently mistaken for manganese ore. On account of the similarity of this occurrence to the extensive iron deposits of northeastern Cuba, it was thought that a brief description based upon a two days' reconnaissance survey of the area would be of scientific interest. Mayaguez is on the west coast of Porto Rico, at Mayaguez Bay, which is the third in importance of the harbors of the island. The city itself is about ¾ mile inland on the low-lying plain at the mouth of the

Jan 3, 1918