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By R. R. Sayers

There is probably no industry , trade , or art in which mercury is used but what has produced some cases of mercury poisoning . This is true of the mining and smelting of mercury , where the hazard has long been recognized . When the ore contains free mercury or the more soluble salts , and when the workings are underground and are poorly ventilated , cases occur , but there are a far greater number of cases among the employees about the reduction works . 3 In 1863 William V. Wells visited the mines at Almaden , * Spain , which were worked by convicts . He reported that the men at the furnaces suffered severely , being able to work only about one week out of four , when it was necessary to transfer them to places where the exposure was less . He states that "pale cadaverous faces and leaden eyes are consequences of even these short periods . " Mercury , like lead , when absorbed in small amounts at intervals , as daily, over an extended period of time will result in symptoms of poisoning . This is due to the fact that the mercury is eliminated from the body more slowly than it is absorbed . The frequency and severity of cases of mercury poisoning are far less with modern methods of mining and recovery of the metal than formerly . However , further reduction is possible and much can be done by both the workmen and the operators by following the proper precautionary measures , some of which are described in this chapter .

May 1, 1922

By A. E. Cameron

The curve of coal production in Nova Scotia over the past forty years shows a definite maximum reached in 1913. Continued production to this maximum will require a greater tonnage per man-day, and this means there cannot be any increase in total man power used in the operations. There are still large reserves of coal but much of it will require washing or beneficiating to make a usable product. By-product recovery based on the present product ion is relatively satisfactory. Further development of secondary industries requires adequate markets for the bulk materials produced by the processing. It also requires access to other raw materials as well as markets for the principal product of the operations. Scientific investigation and research are needed to prove the quantity and value of lower grade or poorer quality coals, and methods for their recovery and utilization. Economics of further processing of present and future production must be investigated beforehand, if a successful development is to be assured. Such development cannot be expected largely to replace present markets. Production of coal for genera l use must continue to form the major function of the coal industry of the Province. Costs per ton must decrease, or subsidies or other assistance must increase, if the industry is to survive. Costs of investigation and research and costs of capital outlay for further development muse be met.

Jan 1, 1944

By Joseph Hodgson

IN 1880, mining operations were commenced at the Copper Queen mine. The famous Queen orebody, which extended to the surface, was first quarried from a large open cut in the outcrop. The orebody was followed down to the 300 level with the Queen incline, and stoped. This, we believe, marks the introduction of square setting in the Bisbee district, which is still the method most generally used. Orebodies The orebodies in the Copper Queen mine occur in the limestones, and the main portion of the ore has been mined from the Abrigo, Martin, and. Escabrosa limestones. While the orebodies outcrop in the extreme western end of the mine, the general dip is to the east and south, at an angle of about 20°, although this dip is not by any means regular, being, in fact, very irregular locally. The ore is remarkable for its variableness in character, some of it being very soft, requiring a large amount of timber, and other portions consisting of extremely hard sulphides. The orebodies, in general, While remarkable for their continuity, are very irregular, both as to shape and size. The mine having been in operation so many years, and mining having been prosecuted over such a large area, the operations have caused the shrinkage of the overburden, and there is a constant movement, which is shown y large cracks and interstices in the surface rocks, which largely contribute to the very high deadwork or maintenance cost of the mine. It is surprising that for year 1913 it cost almost $400,000 just for the one item of repairs and deadwork in this property.

Jan 8, 1914

Liebherr Mining Equipment Co., of Newport News, VA and Baxter Springs, KS, introduced the T282, a new two-axle, diesel-electric, AC drive haul truck with a payload capacity of 327-t (360-st). The T282 was unveiled at a press briefing in October 1998 at the company's Baxter Springs research and development1 manufacturing facility. In addition to an increase in pay- load capacity, the truck's AC drive system has been de- signed to allow for easy configuration to a trolley-assist system with minimal additional equipment. The T282 provides fuel savings, reduced maintenance requirements, and reduced downtime and maintenance costs, providing the mine operator with increases in productivity. Basic dimensions and weight of the T282 are: ? Overall length, 14.5 m (47.5 ft). ? Overall width, 8.7 m (28.7 ft). ? Loading height, 6.5 m (21.2 ft). ? Height - body up, 13.9 m (45.9 ft). ? Empty vehicle weight, 201 t (221 st). ? Operating weight - loaded, 528.6 t (582.6 st). ?Engine, Detroit Diesel 16V4000 at 2 MW (2,750 hp). ?Electric drive system, Siemens/Liebherr.

Jan 1, 1999

By J. P. Dunford

This U.S. Bureau of Mines report describes the development of a yielding steel post for underground mine support. The report covers concept development, laboratory tests, modifications, and field evaluations. The objective of this work was to develop a stiff support member capable both of supporting high loads and yielding when excessive amounts of mine entry closure were present. The 6-to 7-ft steel post was designed to yield nearly 2 ft while maintaining a 45-ton (force) load. The post is a three-piece unit consisting of top and bottom telescoping legs and a separate foot bracket. It develops its load-carrying characteristics when the lower pipe, with an attached interference ring, is forced into the larger top pipe. Laboratory tests were used to determine critical loads and post performance for various post lengths. Field tests showed that the posts could perform in actual mining conditions. The post has the ability to provide support in highly yielding ground and also, because of its slender profile, enhance ventilation and provide more area for travelways and escapeways. The design is simple enough to allow for fabrication at most mine shop facilities.

Jan 1, 1989

By Yong Liu, Peng Qian, Shu-Feng Ye, Shao-Jun Chu, Pei-Wei Han

"Chromite with a low mass ratio of Cr to Fe (Cr/Fe ratio) was treated by the carbochlorination method using solid chlorinating agent (MgCl2 and CaCl2) and carbon in the present paper. The results showed that iron could be selective removed mainly in the form of FeCl2. The removal of iron was indirectly, which consisted of the decomposition of solid chlorinating agent to release Cl2/HCl and the carbochlorination of FeO•Cr2O3 by Cl2/HCl and C. The Cr/Fe ratio increased as increasing temperature from 700 ? to 900 ? in air atmosphere, while the tendency was opposite in N2 atmosphere. The removal efficiency of iron by CaCl2 was better than that by MgCl2. At last, a new pelletizing process was proposed to treat fine chromite with a low Cr/Fe ratio based on carbochlorination method, which could produce the high quality roasted chromite pellets with higher Cr/Fe ratio and compressive strength. INTRODUCTION Chromite is mainly used for the production of ferrochromium. A high Cr/Fe ratio (>2) of chromite is usually required to meet the technical specification of ferrochromium.(Gasik, 2013) Attentions have been attracted to the economic and efficient methods for the recovery of chromium from lower-grade ores as the higher-grade ores become depleted. However, the Cr/Fe ratio is difficult to improve through the conventional beneficiation methods (such as gravity concentration, flotation) due to the spinel composition, although beneficiation methods could increase the metal content of chromite ores by removing gangues.(Nafziger, 1982) The main industrial mineral of chromite is (Fe,Mg)O•(Cr,Al,Fe)2O3, which belongs to spinel magnetite.(Liu, 2013) Iron should be selectively removed through the structural dissociation of spinel to increase Cr/Fe ratio.(Nafziger, 1982)"

Jan 1, 2018

By H. A. Guess

A Discussion of the Paper by Mr. H. A. Guess, read at the Atlantic City meeting, February, 1904. MR. JOSEPH P. GAZZAM, Germiston, Transvaal, So. Africa (communication to the Secretary*) :-About fourteen years ago, in southeastern Missouri, I used a method for the wet determination of lead which closely resembles the modified sulphate-chromate method described by Mr. Guess. The principal difference, however, is, that after dissolving the lead chromate in hydrochloric acid, the chromic acid is determined by means of a standard solution of ferrous sulphate. The method, which I believe is still in use in southeastern Missouri, was found to be convenient and accurate for the determination of lead in the ores and various products of the mills and furnaces in that district, but it was never used for complex ores. A number of determinations of lead in mill-tailings were made in the year 1891; a few of these results are given in Table I.

Mar 1, 1905

By J. J. Pfeiffer, A. A. Oming, J. W. Myers

The method used to process washery refuse for use as a building material aggregate is described. Results of studies made in investigating this process are summarized. The Bureau of Mines, in cooperation with two commercial coal producers, studied the feasibility of using coal washery refuse in manufacturing lightweight aggregate for building materials. Lightweight aggregate is used in making masonry products of lower bulk density than can be produced from conventional aggregate such as sand, gravel, and crushed rock. Among the advantages of lightweight masonry are reduced deadweight loads which reduce materials cost, lower cost of construction labor, and improved thermal and sound insulation. A process for making lightweight concrete aggregate from coal-washery refuse appeared attractive because of the availability of raw material which contained sufficient fuel to carry out the processing. Vast quantities of such refuse have accumulated throughout the coal-producing areas of the U.S. Generally it is stored in unsightly piles, creating a problem of air pollution and using space that could be devoted to other purposes. Conversion of the refuse to lightweight aggregate could remedy these conditions and effectively utilize a material normally considered waste. The first part of the program was conducted in cooperation with the Truax-Traer Coal Co. to determine the feasibility of utilizing refuse from the company's coal preparation plant at Ceredo, W. Va., in manufacturing lightweight aggregate. The aggregate was to be used in making cement blocks comparable to those known in the building trades as cinder blocks. This project was completed in 1954. Based on the results of this work, the cooperator began commercial development and formed the Trulite Corp. for this purpose. A plant capable of handling 120 tpd of refuse was constructed for approximately $120,000. It began operating on June 1, 1955.' In 1959 a similar study was made, under a cooperative agreement with the Carbon Fuel Co. of Charleston, W. Va., to rrscertain the suitability of refuse from its plant for conversion to lightweight aggregate. Under this program various modifications of equipment were made, and the investigation of process variables begun in the previous project was extended. PROCESSING METHOD The formation of lightweight aggregate from coal-washery refuse js governed, in part, by the fusion characteristics of the mineral constituents of the refuse when heated above their softening temperatures. The heat required for this purpose is supplied by the combustihle matter in the refuse. Some of this combustible matter is coal with high ash content, but most of it is carbonaceous shale. Whereas the density of aggregate prepared from clay or shale depends largely on expansion, the density of aggregate made from refuse is reduced by burning out the combustible matter and, to a lesser extent, by expansion of the residue in the fuel bed. A chain-grate stoker with an updraft air system was chosen for the conversion process in preference to a downdraft sintering machine or a rotary kiln. In down-draft sintering, which operates on the overfeed burning principle, the volatile matter from the refuse would distill off without burning, resulting in inefficient combustion and interfering with proper operation of the equipment. The rotary kiln is designed primarily for processing material that lacks, or is low in, combustihle matter with the heat of reaction supplied from external sources. Washery refuse, which is relatively high in carbonaceous material, could burn at the wall of the kiln causing clinker formation with resultant decrease in throughput and increase in production cost. With an up-draft air stream on a chain or traveling-grate stoker, the volatile matter would be carried into the ignition and burning zones where the heat could be utilized more efficiently. The combustion procedure in this type of unit may be considered as consisting of four periods: 1) initial ignition of the top of the bed by furnace radiation, 2) ignition travel through the bed until the whole bed is ignited, 3) burnout of the combustible material with high air rates to fuse and expand the residue, 4) a cooling period. Investigation of the process required a study of the variables that affect both

Jan 1, 1962

By F. J. Sotillo

Mining in Peru is mainly concentrated on metallic and polymetallic ores of gold, copper, lead, zinc, silver, tin, iron, etc. However, little has been done to develop extensive and rich non-metallic or Industrial Minerals deposits with the exception of some silica and phosphate deposits. This paper presents the characterization and metallurgical studies for the development of a feldspar deposit. These studies showed that the special characteristics of the ore, such as high porosity, high Al2O3 content, low clays content, and sized material allowed us to obtain commercial products applying relatively simple and low cost concentrating unit operations. The characterization studies showed that the feldspar products contained no quartz and about 90% of albite (NaAlSi3O8). The 14x40-mesh size fraction product analyzed 5.91% Na2O, 22.56% Al2O3, 65.73% SiO2, 0.65% K2O, 6.50% CaO, and 0.40% Fe2O3; whereas, the 40x150-mesh size fraction product analyzed 6.22% Na2O, 24.30% Al2O3, 60.80% SiO2, 0.91% K2O, 7.06% CaO, and 0.54% Fe2O3. These products could be used for manufacturing glass, ceramics, refractory, and filters in different applications. In addition, Middlings, could be used as insulation material due to its porosity (bulk density of 0.828 Kg/dm3), analyzing 4.46% Na2O, 15.7% Al2O3, 67.2% SiO2, 2.57% K2O, 3.94% CaO, and 4.24% Fe2O3. The material showed a sphericity of 0.77, a roundness of 0.68, and acid solubility of 13.3025% on only washed and 2.72% effective for clean material suitable for use in these applications. No selective accumulation of the valuable mineral was observed at any specific size fraction. However, iron and titanium bearing impurities trended to concentrate in fine fractions (minus 70 mesh -212 µm-). Metallurgical studies demonstrated that this feldspar ore required sizing at 14x40 mesh and 40x150 mesh to render commercial products. In the case of the 14x40-mesh size fraction, the process involved magnetic separation, gravity separation, and flotation for feldspar (direct flotation) using a blend of primary and condensate amines. However, the reverse flotation for mica-biotite and iron bearing minerals was also possible using petroleum sulfonate. The metallurgical process for the 40x150-mesh size fraction required magnetic separation and reverse flotation of iron and titanium bearing minerals, the feldspar being reported in the sink material. Commercial products from this feldspar deposit for glass, ceramics, refractory, and filtration; and for the manufacturing of insulation material were obtained.

Feb 23, 2014

By ZHONGLING ZHAO, WANTING SONG, GUOZHONG LIU, LEIXIN SHI, ZUI WANG, YUANYUAN LIU, KE GAO, DONGHONG JIANG, WANG LUO, PEICHAO LU, Jianwei Cheng, WANCHENG ZHENG, Gang Zhao, YUNGANG WANG, JIANBING ZHAO

Coal spontaneous combustion is one of the disasters occurring in underground coal mines. As a typical case, the spontaneous combustion of broken coal left in the longwall gobs often happen which could greatly interrupt the normal mining production. Such concealed thermal event is featured as rapid development and difficulty in locating “hot” spots. If such spontaneous combustion fails to be timely prevented and controlled, a large amount of toxic gases (mainly CO) and smoke could flow and diffuse in the underground working sections, which could present safety hazards for coal miners. In this paper, based on an coal spontaneous combustion event happened in a Chinese gassy mine, the fire ratios derived from the gas composition data obtained through the tube bundle mine atmospheric monitoring system are used in determining the fire status. A comprehensive and collaborative fire extinguishing effort including inert gas injection, underground pressure balance, and sealing enhancement are made to control the fire progress. Simultaneously, the effects of such works to control the spontaneous combustion event have also been quantified using the fire ratios to justify again. Finally, the danger of coal spontaneous combustion in gob is eliminated, and the longwall panel is successfully re-opened for normal production.

May 6, 2021

By Nelson SOUTO, Nicolas LEGRAND, Sami ABDELKHALEK, Zafer KOONT

A work roll thermal crown model has been developed for a wide range of hot and cold rolling mill applications. The model is extremely fast, robust and accurate to determine the evolution of thermal crown all along the rolling campaigns. It has also ability to consider work roll shifting, multiple segmented cooling zones along the length and circumference of the roll as well as composite rolls properties (e.g. different thermal properties between mandrel and core of the roll). Moreover, the model includes simultaneously fast and slow temperature evolution calculations, respectively near roll surface (skin area) and at a certain distance below the roll surface (bulk area). This gives to thermal crown predictions a higher accuracy than conventional thermal crown models from literature that consider only the slow temperature evolution regime. An optimization procedure together with roll surface temperature and roll thermal profile measurements have been used to tune the model. The tuned model applied to hot rolling conditions has shown a significant influence of roll shifting and composite rolls properties on the prediction of roll temperature distribution and thermal crown during rolling. The tuned model applied to cold rolling conditions highlights the importance of mill operators practices to modify cooling distribution across roll barrel length with the segmented cooling zones to adjust the thermal crown and to get better strip shape control.

Oct 1, 2019

By S. R. Noble, F. R. Harris, E. T. C. Spooner

"The Logtung deposit discovered in 1976, is an example of large tonnage (162 million tonnes), low grade (0.13% WO3 and 0.052% MoS;) W(scheelite)-Mo mineralization related to multiple felsic intrusions. Because mineralization is predominantly fracture-controlled (> 95 %) rather than disseminated, Log tung is not a skarn deposit. Metamorphism of the Logtung country rocks (interbedded calcareous shale and graphitic quartizite) to a series of competent reaction skarns (quartz-diopside-garnet calc-silicate, biotite quartzite and wollastonite-vesuvianite calc-silicate) clearly precedes W-Mo mineralization. Hence mineralization was related to permeability created by hydraulic fracturing and not replacement processes.Logtung shows a theme of several phases of mineralization (4) related to multiple intrusions (>2) which is similar to that of the Climax and Urad-Henderson Mo systems. The earliest quartzmolybdoscheelite vein system, which consists of a typical ""porphyrystyle"" crackle-breccia of thin (0.5 mm to 4 mm) quartz-garnetdiopside- molybdoscheelite veins, is related to a high Si02 (approx. 76%), seriate-porphyritic monzogranite stock (approx. 2 km by 0.5 to 1 km) of Cretaceous age (118 ±2 Ma [2u]; Stewart, 1983). Later quartz-pyrite scheelite (fluorite-KINa-feldspars-molybdenite) veins, with prominent green, hornblende-bearing alteration selvages, and quartz-molybdenite (-pyrite-jluorite-scheelite) veins are related to a quartz-feldspar-spessartine-rich garnet porphyritic felsic dike complex approximately 500 m across. Both intrusive phases have anomalously high Wand Mo concentrations of about 100 ppm and 50 ppm respectively, which Stewart (1983) attributes to a primary enrichment. The final stage of mineralization consists of a prominent 4.5 km by 1 km zone of 1 em to 1 m wide polymetallic sheeted veins centred on the felsic dike complex. The system is zoned from quartz scheelite-molybdenite-pyrite-blue-green beryl-jluoritebismuthinite veins in the core to Pb-Zn-Ag veins with abundant arsenopyrite and minor Sn (approx. 0.1%) in the northeast. The focus of recurrent intrusive and hydrothermal activity was located above a flank or nose of the monzogranite stock.The distribution of WO3 and MoS2 grades within the approximately 750 m (across) by 300m (evaluation depth) mineralized zone is a result of the variable superimposition of the four separate vein systems each with different W:Mo ratios. Well-defined Wand Mo ore, shells such as those at Climax, Henderson and Mt. Emmons did not develop at Logtung. The upper surface of the mineralized zone, as shown by the 0.03% MoS2 contour defines an elongate dome with an apical region approximately coincident with the felsic dike complex. Hydrothermal alteration occurs as well-defined vein selvages, and not as pervasive zones.The Logtung deposit shows many similarities to porphyry Mo deposits in the western Cordillera and may be identified as a porphyry W(scheelite)-Mo deposit, with a W:·Mo ratio of 3.3:1. The principal reasons are: (1) mineralization is spatially associated with porphyritic granitic intrusions and (2) much of the scheelite and molybdenite occurs in typical ""porphyry-style"" vein stockworks"

Jan 1, 1995

By Mike Santaluce

Smelting furnace rebuild projects often require a significant capital expenditure and an extended smelter outage. Smelter operators are increasingly searching for methods and initiatives to shorten furnace rebuild schedules, maintain manageable cost levels, enhance furnace performance and achieve excellent safety results. This paper describes the ?MEPC? Model for furnace rebuilds; a project driven approach which Auburn has developed in response to the need for improving furnace rebuild project outcomes. The ?MEPC? (Management, Engineering, Procurement and Construction) approach better addresses the unique challenges presented by furnace rebuild projects when compared to the traditional EPCM (Engineering, Procurement, Construction Management) model widely in use for these projects today. One key feature of the MEPC model is that a dedicated project management team with representation from all of the major project stakeholder groups is put in place at the onset of the project. The project management team has ownership and accountability for meeting overall project goals over the entire lifecycle of the furnace rebuild project. A second key aspect of the model is emphasis on project management as a completely separate project function with its own specific skill sets, techniques, tools and best practices. These features of the MEPC model offer several advantages in terms of improved planning, coordination, communication and alignment with project goals which contribute to the overall success of furnace rebuild projects. Similar MEPC concepts have been used to deliver excellent project results in other industries and the MEPC approach has been successfully utilized on furnace rebuild projects.

Jan 1, 2006

By Andrew B. Allen, Charles W. Robinson, Robert L. Schneider

In April, the US Synthetic Fuels Corp. broke a three-year silence and made its first financial award by approving a $820,750 loan for the First Colony peat-to-methanol project in North Carolina (ME, May, page 403). Peat Methanol Associates (PMA), a partnership between Koppers Co., ETCO Methanol Inc., Transco, Peat Methanol Co., and l. B. Sunderland, broke ground at First Colony last year and plans to begin production in Dec. 1985. Although the award is only a small part of Synthetic Fuels Corp.'s $15-billion budget, it does signal the corporation's intention to move aggressively ahead. It also is a positive indication that First Colony will be completed and operated successfully. This article describes the methods and equipment that will be used to harvest peat at First Colony, as well as how the peat will be converted to methanol. Introduction Peat deposits found along North Carolina's coastal plain contain high-quality fuel-grade peat with an average heating value of more than 23.3 MJ/kg (10,000 Btu/lb) (dry), with a low sulfur and ash content. The deposits differ from other US peats in that they contain large, sound Atlantic White Cedar and Cypress logs, stumps, and roots that may extend throughout the full depth of the deposit. A second difference is that these deposits are much more highly decomposed and, in the raw state, have the appearance and feel of a heavy, reddish-brown grease. These factors make it impractical to use standard production equipment so a new line was developed. Also, because of these conditions, techniques were modified to facilitate production. First Colony Farms, located near Creswell, NC, developed and evaluated a milled peat program. Equipment for this production method was designed and built, production rates were established from field operations, drying rates were established, weather data were analyzed, and total operating and capital costs were estimated. The method depends on the sun and wind for drying peat to the desired moisture content, in this case around 40%. Therefore, field preparation is actually the construction of a large solar collector to dry the peat so it can be harvested and stockpiled. It is essential that this collector be properly profiled initially and maintained during production to prevent precipitation from ponding. Initial Field Preparation Initial field preparation includes cleaning existing canals and constructing ditches and water control structures for proper drainage of rainwater run-off, building adequate roads for site access, removing surface vegetation, and profiling and sloping the fields. At First Colony, the 60.7-km2 (15,000-acre) harvesting area was divided into 129.5-hm2 (320-acre) blocks about 1.6 km (1 mile) long and 805 m (0.5 mile) wide. This was accomplished by cleaning main outfall canals with adjacent roads built from canal spoil at 1.6-km (1-mile) intervals. Existing intermediate canals that feed into main outfall canals at 805-m (0.5-mile) intervals also are cleaned. Headland roads are constructed from canal spoil along each side of each intermediate canal. This 129.5-hm2 (320-acre) block is then divided into 32 harvest strips by small V-ditches constructed at 50-m (165-ft) intervals. At the end of the field with the lowest elevation, corrugated steel pipe culverts are installed under the headland road in each V-ditch to control rainwater runoff into intermediate canals. Runoff water from the fields is diverted to a holding pond to prevent any increase in peak water runoff rates and to allow for more uniform drainage rate than experienced to date. After the drainage system is installed, harvest strips are ready for grinding and sloping operations. Surface vegetation, made up of small, waxy-leafed shrubs such as Gallberry, Bayberry, Magnolia, and scattered pond pine, can be effectively ground and incorporated into the upper surface of the peat layer. Here, it will rapidly decompose and have little effect on overall peat quality, thus eliminating the standard practice of pushing the vegetation and upper wood layer into long windrows with bulldozers and hauling this debris from the fields. Incorporating vegetation into the upper surface is known as the initial 102-mm (4-in.) surface vegetation grind and is accomplished by using a modified Bros Rota Mixer. Following this operation, and by using the same unit, a sec¬ond grind with a depth of 200-255 mm (8-10 in.) is made. This reduces the debris to a finer consistency, mixes it with the upper peat layer, and grinds any wood found in the upper 200-255 mm (8-10 in.). After initial grinding operations are completed, the augering or sloping operations can be accomplished with little or no hin-

Jan 7, 1983

By R. R. Brown

The Bureau of Mines undertook a limited feasibility study to determine the practicality of removing copper from automobile scrap by thermal treatment. Test specimens, prepared by wrapping bare and insulated copper wire around small steel coupons, were heated at 600° to 1,150° C in various atmospheres for different lengths of time under both static and dynamic conditions. The tests indicated that adequate removal of copper cannot be effected by thermal treatment of scrap above the melting point of copper. Tests showed that copper present in scrap as insulated wire is embrittled by thermal treatment at 800° to 900° C if the insulation contains lead, and that the embrittled copper is almost completely removed by a mechanical action such as tumbling. Also chemical pretreatment of specimens to effect embrittlement of copper and the magnetic separation of oxide scale were studied. Tests showed that bare copper can be embrittled by depositing waterglass (Na, Si409) on copper prior to thermal treatment.

Jan 1, 1968

By M. A. Alan

The Bellavista Gold Deposit lies 75 Kms north west of San Jose, the capital of Costa Rica, Central America and 3 Kms north east of Miramar, in the Province of Puntarenas. The total road distance from San Jose to the deposit is 120 Kms all paved road except for a 2.5 Km graded, gravel road on the property (Figure 1). Infrastructure services in the Miramar-Puntarenas area are well developed with electrical power distribution, a modern port facility and community services being available. The deposit lies on the south west flank of the Tilaran Mountain Range between an elevation of 550 and 800 meters above sea level. The local topography is steep, originally covered with pre-montaine, tropical wet forest vegetation which has been largely destroyed due to clearing for cattle grazing. The annual rainfall is approximately 2,950 mms, 90% of which occurs between May and October.

Jan 1, 1992

By W. W. Adams

"A recent paper prepared by the writer summarized the results of an analysis of the accident records of 34 metal mines for the calendar year 1925. The present paper summarizes the results of a similar analysis of the accident records of 59 coal mines for the same year. This summary is based upon reports furnished to the Bureau of Mines, Department of Commerce, by operating companies that par¬ticipated in the National Safety Competition of 1925.The purpose of the Competition was to establish the lowest accident-severity rate, thus showing the smallest loss of time from accidents in proportion to total number of man-hours worked. The reports covered all lost-time accidents that occurred during the year, that is, all accidents that disabled an employee beyond the day or shift on which the accident occurred. Detailed information for each of the 59 coal mines is given in the appended table. Each mine employed at least fifty men underground; over half of than employed more than 200 men underground. Hence the accident records should be typical of those of large-scale mining operations in general where the company is devoting special attention to accident-prevention work. The mines covered by the reports are situated in eleven States: Alabama, Illinois, Indiana, Kentucky, Maryland, Ohio, Pennsylvania, Tennessee, Utah, Washington, and West Virginia.A tabulation of the reports covering the 59 mines showed an accident-frequency rate of 123 per million hours of ""exposure* and an accident-severity rate of 10.214 per thousand hours of exposure3. The total volume of exposure or employment was 29,117,561 hours, representing the equivalent of work of 12,000 men for three hundred 8-hour shifts. The records covered employment and accident above ground as well as underground, although they did not include stripping or open-pit mining. Accidents during the year resulted in 33 deaths, 1 permanent total disability, 28 permanent partial disabilities, and 3,510 temporary injuries. These accidents represented a loss of tine equal to 297,417 man days. In arriving at this lost-time equivalent, each fatality and permanent total disability was weighted at 6,000 lost days (see footnote 3), as specified in the scale adopted by the International Association of Industrial Accident Boards and Commissions; permanent partial disabilities were weighted according to nature of injury, in accordance with the scale adopted by the :Board; temporary injuries were weighted according to the actual number of calendar days during which the employee was incapacitated as a result of the injury."

Nov 1, 1926

By AIME AIME

IT is unlikely that any oil field has ever threatened the future course of the oil industry as does Kettleman today. It seems that nature has striven to outdo herself in combining in this field every possible factor conducive to a tremendous production of the petroleum product in greatest demand-gasoline. This field already has 13,700 acres of proved land and an oil zone of known thickness of 1400 ft. It has wells yielding several thousand barrels of oil of virtually motor fuel grade, together with millions of cubic feet of gas at almost unheard of pressures. The field would have been the. answer to an oil man's prayer in times of under-supply, but now it is the oil man's nightmare, for drilled in -the manner of most other fields and without regard to available markets for oil and gas, the greatest physical and economic losses in the his¬tory of the oil industry will result.

Jan 1, 1930

By John G. Groppo, James C. Hower, Cortland F. Eble, Rick Q. Honaker, Alireza Valian, Stephen F. Greb

Coal and coal combustion byproducts are potential candidates for alternative resources of REEs (rare earth elements). The Illinois Basin is a major coal-producing district in the USA, but little work is available on speciation of REEs in the basin’s coals. In this study, a total number of 382 samples from known locations in the Illinois Basin coal beds were acquired, analyzed for their REE contents, and investigated for any spatial trends or chemical correlations. This study includes Springfield, Herrin, and Baker coal beds—the most heavily mined coals in the basin. An average coal ash from the basin contains 320 ppm REE, with Baker being the highest (407 ppm on average). However, the distribution of REEs in the coal beds was laterally and vertically heterogeneous. A number of trends were found in the REE variations. The most important trend was the relationships of the REE concentrations and fractionations with the distance from the syndepositional sandstones. The total REE concentrations were higher in the proximity of the sandstones, likely due to the increased deposition of detrital material. This increase was the most significant in Springfield coal (90%) and least in Baker (6%). Those coal samples from the Springfield and Herrin coal beds distal from the syndepositional sandstones had a heavy to light REE ratio (H/L ratio) of 0.40 on average, whereas in proximal locations, the ratio was dropped to an average of 0.30. This trend was not significant in the Baker coal bed. In general, higher mineral matter in the coals was associated with higher REEs. In coal preparation plants, refuse rocks can have up to 360 ppmREE. However, the ashes of the cleanest coals had higher REE levels. Such ashes also have a higher ratio of heavy to light REEs. The highest REE concentrations were found in the claystones and the shales associated with the coal beds. Since the naturally occurring calcite, quartz, and pyrite samples were depleted in REEs, an association of REEs with the clay minerals can be suggested.

Jul 20, 2020

By Fernando Enrique Toledo Garay

"El presente texto describe las últimas tendencias de la ISO 55000 y así conocer el objetivo de las normas como de los estándares asociados a la gestión de activos físicos. Por ello, se realiza un recorrido a través de todo el IAM Framework (marco de referencia del Institute of Asset Management para lograr la sustentabilidad de la gestión optimizada de activos físicos) e ISO. dencias en las organizaciones de apoyo. En este análisis participan representantes de todas las áreas del negocio de gestión integral de activos físicos (operaciones, mantenimiento, materiales, ingeniería, finanzas, recursos humanos, confiabilidad, seguridad industrial y medioambiente). "

Jun 1, 2015