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By CAIJUN CHEN, MING ZHANG, ZHENWEI WU, FENG ZHOU, BOQUAN LI, XILIANG ZHANG, ZHOU PU

Traveling grate is a widely used process for iron ore pellet production; however, the thermal state of pellets in drying section is still unclear. In this study, the temperature distribution of drying section was investigated using computational fluid dynamics (CFD). Based on the calculated results of airflow velocity, space temperature distribution, and the temperature change of pellets, it concluded that there is a coupling effect in drying section in traveling grate. The gas with higher temperature in DDD transfers heat to UDD through the gap of the insulation board, and the temperature gradient of the pellet bed changed before reaching the insulation board. The characteristics of pellet bed expected to appear in DDD was displayed in UDD in advance. Moreover, a contrast experiment was conducted to verify the model.

Feb 1, 2021

By Jorge Cárdenas, José Luis Hurtado

The critical distance determination test through direct recording for the mine in Phase 03 was carried out in January 2024, and in it the vibration and pressure models were obtained for the Sedimentary breccia unit. The method of obtaining the records is based on the capture of individual pressure waves generated by distant loads, sequenced in periods of 600 ms for easy identification. The test set up corresponds to a variation of that used to obtain the vibration model, and uses 08 wells for loads and 04 for instrumentation. The results apply a safety factor of 1.2 and 1.5, being 16,000 PSI and 13,250 PSI respectively. The values are valid for any distance greater than 5.5 m, this being the minimum established between wells for loads according to the configuration defined in the field, also considering that in 5.0 m of instrumentation the section of the drill hole with the sensor called S1 collapsed. The results of the analysis of the test, generated with Heavy Anfo 82 explosive, with a final density of 1.15 g/cc, are presented. The results of the modeling and generation of the graphs and tables presented show behavior in line with the concept of scaled distance. It is important to consider that in water conditions there is a high impact by the condition, which causes the records to be higher than those expected in dry conditions and present less variability. It is for the above reason that the row corresponding to distance with safety factor 1.5 is declared valid. The results are only valid for the rock analyzed, whose medium is homogeneous and constant in terms of lithological composition and that present similar resistance characteristics, fracture frequency and water table levels. As future steps, the objective is to quantify the increase in pressure generated between wells by analyzing time and sequence factors. This analysis aims to explain the occurrence of dynamic pressure events in areas where critical safety distances are observed.

Jan 21, 2025

By Hunsoo Choi, Sung Rock Lee, Ian J. Graham, Ian C. Wright

This is a part of the joint KIGAM-GNS-NIWA 3-year study of ferromanganese modules in the Campbell Nodule Field, east of Campbell Plateau to determine age distribution, growth rates and geochemical evolution in relation to geographic setting. The petrography, chemistry, inferred genesis, and 10Be/9Be dating of the nodules were described in the science report of GNS (Chang et al., 2003a, 2003b; Graham et al., 2003a) and presented at UMI (Chang et al., 2003c; Graham et al., 2003b). The morphology and distribution of ferromanganese nodules were also published in detail (Wright et al., 2005). This presentation is only concentrated on the mineralogy and chemistry of the nodules.

Aug 24, 2006

By William G. Pariseau, H. Douglas Dahl

Recent subsidence legislation indicates that mining engineers would be welt advised to be able to predict and control surface damage caused by mine subsidence. To date, such an ability is practically nonexistent. Model analysis is suggested as one of the alternative paths available which might yield fruitful results. Similitude requirements developed for a self-loaded body in static or quasi-static equilibrium indicate that complete similitude without centrifuging is an impracticability. However, a pilot experimental study which used a simplifying assumption to correctly model mine subsidence has produced results in qualitative agreement with field observations. The purpose of this paper is to present a discussion of the various approaches that can be taken in the study of mine subsidence phenomena. Particular attention is focused upon the rational selection and use of laboratory models. Broadly interpreted, mine subsidence is the deformation of the rock mass enclosing a mine. Depending upon a number of factors, the movement of the subsiding rock mass may disrupt gas and water lines or other buried utilities, damage surface structures such as buildings and bridges, dislocate streams, roads, and rail lines, aggravate acid mine drainage and fire problems, and generally mar the landscape. It is clearly a problem that no mine manager can safely ignore. It is also a problem that will grow with the general population increase. In the following discussion, a summary review of past and present approaches to subsidence studies is given. The possibilities of duplicating subsidence phenomena in laboratory models are examined, and an analysis of a particular type of model is presented. Some preliminary results obtained from a model of the particular type analyzed are then discussed. REVIEW OF PREVIOUS WORK Historically, subsidence investigations have been empirical studies in the field and laboratory or theoretical analyses of mathematically idealized media. Empirical and theoretical work in the United States has generally lagged behind investigations abroad. In the United States, field studies are mostly pre-World War 11. These are summarized in the Mining Engineer's Handbook. ' Field studies in Europe are more recent and more extensive. Those made in Great Britain are summarized in the Subsidence Engineers Handbook2 and represent observations made at 157 different collieries. Such studies by themselves are of limited usefulness as are all empirical studies. One can never be certain that conditions at one mine will be similar enough to those at another to warrant the drawing of like conclusions. European subsidence formulas rely heavily upon the "angle of draw" and "critical area" concepts. The angle of draw is defined as the angle between a vertical line through the face, and another line extending from the face to the surface at the point where movement is zero. The critical area is defined in relation to the least extraction necessary to produce maximum subsidence. Fig. 1 illustrates the angle of draw and critical area concepts. First and second "limits of influence" are also shown. The angle of draw and associated critical area concept are obviously not well defined, being dependent upon the accuracy of the surface survey. In Great Britain, the angle of draw has increased through the years from about 26 to 35°. In the United States, zero and negative angles of draw have been reported. In the authors' opinion, these purely geometrical concepts represent an oversimplification of subsidence phenomena and their use, in the United States at least, should be discouraged. Empirical observations of laboratory models containing layers of earth, sand, clay, and plaster were made by Fayol (cited by Peele) as early as 1885. An outgrowth of his work was the "dome theory," a verbal description of what is assumed to occur in subsiding rock masses. The dome theory has since fallen into disrepute. Theoretical analyses worthy of the name treat a subsiding rock mass as a deformable body. In these analyses, the actual rock mass is replaced by an idealized material that deforms according to a simple stress-strain relationship. The stress equations of equilibrium expressing the Newtonian laws of mechanical action and the geometry of strain furnish additional equations that must be satisfied. A loading criterion-generally understood, and in some cases stated explicitly-completes the theory.

Jan 1, 1969

By O. A. W. Strydom, J. C. M. Wethmar, P. R. Jochens, D. D. Howat

Liquidus temperatures in the Cr-Fe-Si system in the composition range representative of ferrochromium-silicide produced in South Africa J. C. M. Wethmar, B.Se. (Eng.) Rand D. D. Howat,U B.Se. (Glas.), Ph.D.. F.I.M. P. R. Joehens, Pr.Eng., M.Sc. (Eng.) Rand, Ph.D., A.I.M. O. A. W. Strydom, M.Sc., Ph.D. Alloys in the composition range of chromium, 20 to 50 per cent, iron, 10 to 30 per cent, and silicon, 25 to 55 per cent, were subjected to both differential thermal analysis and the classical quench method so that the liquidus temperatures of ferrochromium-silicide alloys could be determined. The results are presented as liquidus curves on pseudo-binary sections at various ratios of chromium to iron and as liquidus isotherms in the ternary section.

By G. M. Wilemon, J. G. Davis, R. G. Swanton, B. J. Scheiner

The US Bureau of Mines has conducted investigations on extracting phosphate values from wastes generated during the mining and beneficiation of phosphate matrix. These wastes may contain up to one third of the phosphate originally present in untreated ore. Samples of wastes were air-dried and leached using 93% sulfuric acid in the presence of methanol. Evidence for the formation of a calcium sulfate hemihydrate coating that hinders complete dissolution of phosphate is presented. Solid-liquid separations were enhanced when flocculation was effected using poly(ethylene oxide) (PEO) in conjunction with hydroxypropyl cellulose (HPC) or hydroxyethyl cellulose (HEC). A conceptual flowsheet for a proposed process using an acid-alcohol leaching technique is presented.

Jan 1, 1991

By J. A. Vezina

The effects of particle size distribution on metal extraction have been determined from pressure leaching Renzy Mines Limited concentrate with oxygen. Using a pulp density of 30 per cent solids, an oxygen pressure of 80 psig, a temperature of 230°F, a grind of 2.5 hours and a retention of 8 hours resulted in the almost complete dissolution of the nickel and the cobalt and the decomposition of over 96 per cent of the chalcopyrite finer than 20 microns. Only 11 per cent of the chalcopyrite coarser than 20 microns was reduced to smaller than 20 microns.

Jan 1, 1973

By B. Schulz, T. Leißner, R. G. Merker

"Ores enriched in critical rare earth elements (CREE) keep on being of particular interest. The CREE are Nd, Eu, Tb, Dy, including Y. In conjunction with beneficiation tests on Y-mineral bearing flotation tailings of complicated mineralogy, the Mineral Liberation Analyses (MLA) was used to work out processing characteristics fraction-wise in terms of modal mineralogy, mineral recovery, locking and liberation, and particle size.Size fractions from mechanical sieving (“real fractions”) as well as fractions created virtually by using filters on the MLA-data of the unsieved head material (“virtual fractions”) were investigated comparatively thereby. The ""virtual-sizing-approach"" features a much simpler sample preparation procedure and considerably lower cost if a fraction-wise investigation of a head sample is needed. It can be conveniently applied to intimately locked ores needing a fine grinding to a particle size distribution (PSD) range below 25 microns for instance. However, its practical use is sometimes disputed in terms of the reliability of the results. Results are shown for the main Y-bearing mineral xenotime and selected main gangue minerals of a low grade REE-ore.The influence of sample representativeness, sample preparation and particle counting statistics turned out to be of crucial importance. Given that all preconditions for reliable results are met, locking characteristics, modal mineralogy, and even PSD trends can be read from virtual fractions.The authors encourage processing engineers to use the virtual approach. They propose practical measures to improve the reliability of the MLA results, identify and tackle conflicting results, and mitigate evaluation problems that may arise."

Jan 1, 2016

By Ann Hubbs, Vincent Castranova, Jane Y. C. Ma, De-Hwa Chao, Joseph K. H. Ma

AN OVERVIEW OF THE ACTION OF TETRANDRINE ON SILICOSISBecause of the persistent presence of silica dust in the lungs silicosis is a progressive and irreversible disease. At present, there is no proven effective therapy for silicosis. Limited choices of therapeutic intervention with corticosteroids and other immunosuppressive regimens 1,2 have been accepted for some forms of pulmonary fibrosis. These treatments are only minimally effective, and the results provide little understanding of the disease state due to the lack of correlation between drug activity and the mechanism of fibrosis. Thus, continuing effort must be made in the search for effective antifibrotic agents, which may be used to provide a sequential analysis of the fibrotic process and to open the door for further research and clinical development. Tetrandrine is one of hundreds of drugs screened for antifibrotic activity by Chinese scientists. It has been used in China as a treatment for silicosis in open clinical trials3 and in laboratory animals. The action of tetrandrine on pulmonary fibrosis has been attributed to its ability to inhibit particle stimulation of alveolar macrophages, a key cell type central to the fibrotic process, to release oxygen radicals and inflammatory cytokines. Alveolar macrophages (AM) residing on the alveolar wall, are the predominant phagocytic cells of the lungs responsible for pulmonary defense against inhaled microorganisms and other particles and thus play an important role in maintaining the homeostasis of the lungs. 7 Ample evidence suggests that cells of the monocyte-macrophage series play an important role in the immunopathogenesis of pulmonary fibrosis. When upregulated by silica, alveolar macrophages generate reactive oxygen metabolites8·9 which can damage lung parenchyma and release fibrogenic growth factors and cytokines, 10,11 such as interleukin 1 (IL-1), which can induce fibroblast proliferation and collagen synthesis. The cytokine-mediated fibroblast proliferation and collagen synthesis are key steps in the development and progression of pulmonary fibrosis .11 Previous studies by our group have shown that tetrandrine exhibits strong binding affinity to AM and inhibits particle-stimulated respiratory burst activity (oxygen consumption, superoxide anion release, and hydrogen peroxide secretion) in these cells. 13 In addition, studies by Kang et al. 14 have reported that tetrandrine inhibits silica-induced release of fibrogenic factors such as IL-1 which are capable of inducing fibroblast proliferation and collagen synthesis. Reist et al. 15 further suggested that the antifibrotic action of tetrandrine may be mediated in part by the direct effect of this drug on the ability of fibroblasts to respond to proliferative agents. These results indicate that the mechanism of silicosis involves activation of AM and fibroblasts by silica, resulting in abnormal collagen production due to miscommunications between the cell types. Tetrandrine may interrupt this process by direct interaction with the lung cells.

Jan 1, 1998

T. A. Rickard, Denver, Colorado: The observations made by the author concerning the treatment of gold-bearing ores, deal with the subject only briefly and in a general way; but, coming from an authority, they invite comment. In stating the fact that a " finely-divided condition " is a necessary characteristic of ores containing free gold, the author must be refer ring to those mining districts only with which he himself is ac quainted. The statement would not be true of certain gold-mining regions in America and Australia. The ores of some Californian mines and the mill-stuff treated at certain of the mills of Clunes and Ballarat in Australia, and of Otago in New Zealand, contain the gold in a free but in a coarse state. Moreover, "reduction to fine sand and flour" is not required by certain ores, even though the gold be in a finely-divided condition. In such cases the gold becomes de tached from the quartz before the gangue has been pulverized into particles as small as those in which the gold occurs. The dry-crushing of free-milling gold-ores is onknown in the new mining regions of the world. It is not clear whether the author has in mind any European district in which such a process is in actual use. If he has, a description of the method and the results obtained would be very valuable. Dry-crushing is, other things being equal, twice as slow and twice as expensive as wet-crushing. In the case of free-milling gold-quartz it serves no purpose, since such ore does not carry sulphides which contain any large percentage of value, and which, by being slimed, may carry away part of that value. The dry-crushing of a free-milling gold-quartz would be considered an absurdity by an American metallurgist. If the ore contain "free gold only," why submit it to a further treatment, such as concentration, after its passage over the amalga mating-plate ? What does the author propose to concentrate ? Again, why anticipate the treatment of tailings by the McArthur Forrest, or some other process ? The satisfaction felt by a mill-man in saving gold by a subsequent treatment of the tailings from his mill appears to me to be like that of the man who shoots at a rabbit,

Jan 1, 1894

By Joseph S. Malesky

As essential as the discovery of coal was to our state of advancement, the discovery and development of explosives marks one of the most important findings in the history of civilization. For this reason explosives are rightfully referred to as the forerunner of progress. Without explosives our vast economic enterprise concerning the mining of coal, copper, iron, aluminum, and various other ores could not function. Explosives are used in all kinds of construction works, in the razing of old buildings, blasting of trenches, driving of tunnels, and in many other instances common to our everyday life. An explosive may be defined as a substance (usually a mixture) that, where flame or shock is applied, yields readily to rapid combustion or oxidation, accompanied by the formation of such relatively large quantities of gases as to produce much violence and pressure which, in turn, react against their surroundings and cause what is termed an explosion. By their very nature the action of explosives is destructive and disruptive of adjacent materials. Decomposition of explosives can occur through deflagration, which is rapid burning or combustion, as in the case of black powder, or through detonation, which is an almost instantaneous disruption, as in the case of dynamites and blasting agents. HISTORY OF BLASTING WITH EXPLOSIVES At one time workmen obtained stone blocks for building by grooving the rock with crude picks, driving wooden wedges into niches in the rock, and pouring water on the wedges; the swelling of the wood forced out the blocks. As late as the 17th century, fires were placed against the face of rock to crack it, and water was sometimes dashed on the heated rock to shatter it by sudden cooling. The progress of our country is synonymous with advancement of the improved manufacture and extended use of explosives. Coal had been

Jan 1, 1973

By Samantha Whisman, James R. Hein

Hydrothermal marine manganese-oxide deposits (HMMD) are cemented and variously replaced volcaniclastic and biogenic sediments that were mineralized by distal, low- temperature, hydrothermal fluids. HMMD predominantly form below the seabed as sediment-hosted statabound deposits but can also form on the seabed. These deposits form at oceanic and back-arc basin spreading centers, volcanic arcs, and mid-place hotspot volcanoes. HMMD have traditionally not been considered to have an economic potential because they were considered to be devoid of economically valuable critical elements. This contrasts with their non-hydrothermal counterparts, ferromanganese crusts and nodules, which are enriched in many critical elements. However, manganese is now one of the critical metals and HMMD have the highest manganese contents (up to 55% Mn, so- called battery-grade Mn) of all the types of deep-ocean mineral deposits. There is a growing demand for this critical metal and an upward trend exists in the price of manganese on the global market. Also, other critical elements can occur in high concentrations in some HMMD and their economic potential has not been considered, especially for lithium (up to 0.17%) and molybdenum (up to 0.24%), but also vanadium (to 820 ppm), chromium (to 346 ppm), and nickel (to 0.45%), among others. Which of these critical elements are enriched and their concentrations depend on the types of rocks leached at depth by the hydrothermal fluids, the composition of hydrothermal minerals precipitated in the higher temperature parts of the circulation system, and the types of sediments mineralized by the manganese oxides. For example, mineralization of a carbonate sediment resulted in the highest lithium contents, whereas leaching of ultramafic rocks at depth as a rule results in the highest chromium and nickel contents in the HMMD. These deposits are known to be widespread, especially in volcanic arcs, but their lateral and vertical extents and consequently size, tonnage, and grade have not been determined. Most samples of hydrothermal deposits have been collected by dredging and therefore the in situ relationships often are not known. One sample from the Mariana volcanic arc, west Pacific, was collected by ROV at 1274 m water depth from a layered outcrop 6.6 m thick that may be a sequence of pervasively mineralized volcaniclastic layers and offers the first clue as to the potential vertical extent that these deposits may attain. However, only the top ~0.4 m-thick layer was sampled, so it is not known whether the mineralization extents throughout the outcrop. Although large manganese deposits of various origins occur on the continents, they consist of manganese carbonates, silicates, or complex mixtures of manganese minerals. In contrast, marine hydrothermal HMMD exhibit relatively simple mineralogy that would make processing of this potential ore much simpler.

Jan 1, 2018

By M. Gericke

Over the past few decades the commercial application of heap bioleaching technology for the extraction of base metals has become increasingly important, due mainly to the depletion of high-grade ore reserves. Heap bioleaching is widely used for the extraction of copper from secondary copper sulphide ores. The design and engineering aspects of the process have received considerable attention, but issues related to the microbiology of the process have been subjected to less rigorous scrutiny. The major role of micro-organisms in bioleaching processes is to catalyse the regeneration of ferric iron and protons, from ferrous iron and by sulphur oxidation respectively. It is accepted that even the most carefully engineered heaps are heterogeneous in terms of temperature, pH, the presence of anaerobic pockets, irrigation efficiency, and dissolved solutes. Since interactions between solution chemistry, mineralogy, and microbial populations exist in heaps, a better understanding of the correlation between microbial numbers and types with changes in these chemical and physical profiles with time would be beneficial during process design and operation of heaps, and could result in faster start-up times and higher metal recoveries. This paper reviews the role of microbiology in heap bioleaching processes. Aspects such as microbial diversity, identification and monitoring of cultures, inoculation strategies, colonization behaviour, and tolerance to metals and salts are discussed, and the potential contribution of the knowledge to the improvement of the operation and design of heap bioleach processes assessed. Conclusions are drawn with respect to the role of genetic engineering, heap inoculation practises, and remaining areas for future heap bioleaching research and development.

Jan 1, 2012

By John L. Boardman, C. W. Goodale

The motives behind the organization of the Bureau of Safety were twofold. First, there was the policy of the company toward its employees, which was one of fairness and consideration for their welfare and which entails the prevention of injuries; second, in order to prevent injuries, a study of their causes was essential, and this study could be made only by a thorough systematic classification of accidents, which required a special department to form and carry out the plans. The Bureau of Safety was organized to begin operation Jan. 1, 1914, hut practically all of the first year was spent in collecting data, making plans, etc. This department is semi-independent of others and reports directly to the president and general manager. It consists of the president of the company and the managers of the following departments: Mines, Washoe Reduction Works, Great Falls Reduction Works, Coal department, lumber department, B. A. & P. railway; and the chairman of the Bureau of Safety. Working under this group is the General Safety Committee consisting of the manager of mines, as chairman, the general superintendent, two assistant general superintendents, and the heads of the following departments: mechanical, geological, purchasing, sampling works, and framing plant; and also the safety engineer. Operating under the General Safety Committee are the group safety committees, consisting of the Anaconda group of mines, Boston & Montana group of mines, zinc group of mines, Washoe reduction works at Anaconda, B. & M. reduction works at Great Falls, coal department, lumber department and the R. A. & P. railway. Each of these group safety committces was in charge of the superintendent or manager of the group represented and the committee consisted of the foremen of the mine's or works that the committee served, as well as the safety engineer. These foremen and superintendents had met regularly for the purpose

Jan 1, 1923

By John L. Boardman, C. W. Goodale

The motives behind the organization of the Bureau of Safety were twofold. First, there was the policy of the company toward its employees, which was one of fairness and consideration for their welfare and which entails the prevention of injuries; second, in order to prevent injuries, a study of their causes was essential, and this study could be made only by a thorough systematic classification of accidents, which required a special department to form and carry out the plans. The Bureau of Safety was organized to begin operation Jan. 1, 1914, hut practically all of the first year was spent in collecting data, making plans, etc. This department is semi-independent of others and reports directly to the president and general manager. It consists of the president of the company and the managers of the following departments: Mines, Washoe Reduction Works, Great Falls Reduction Works, Coal department, lumber department, B. A. & P. railway; and the chairman of the Bureau of Safety. Working under this group is the General Safety Committee consisting of the manager of mines, as chairman, the general superintendent, two assistant general superintendents, and the heads of the following departments: mechanical, geological, purchasing, sampling works, and framing plant; and also the safety engineer. Operating under the General Safety Committee are the group safety committees, consisting of the Anaconda group of mines, Boston & Montana group of mines, zinc group of mines, Washoe reduction works at Anaconda, B. & M. reduction works at Great Falls, coal department, lumber department and the R. A. & P. railway. Each of these group safety committces was in charge of the superintendent or manager of the group represented and the committee consisted of the foremen of the mine's or works that the committee served, as well as the safety engineer. These foremen and superintendents had met regularly for the purpose

Jan 1, 1923

By J. W. Gwinn

THE underground haulage system in the lead-silver mine of the-Bunker Hill & Sullivan Co., situated at Kellogg, Idaho, is the most extensive in the Coeur d'Alène district, comprising about 35,000 ft. of tunnels, drifts, and cross-cuts where locomotive haulage is in use. The main working adit, known as the Kellogg tunnel, or No. 9 level, is approximately 10,000 ft. in length from the portal to the main working shaft and extends beyond that about 4,500 ft. in each of two directions. On this level all the ore from the Bunker Hill & Sullivan, the Sierra Nevada Consolidated, and the Caledonia Mining Co. an average of 44,600 tons per month-is hauled to the mills, located a short distance from the portal. Electric haulage by the trolley-type locomotive is used on this level throughout. Below this level, at intervals of 200 ft. vertically, are five other working levels (Nos. 10, 11, 12, 13, and 14); and the total haulage distance on these, where electric locomotives are used, is approximately 16,000 ft. No. 13 level has but recently been opened up and is not working-to capacity; while the main cross-cut on No. 14 has just been started, and has no need of power haulage. Of the four levels equipped with electric haulage, Nos. 11, 12, and 13 have storage-battery locomotives, and No. 10 still retains the trolley type by reason of the small and decreasing tonnage produced.

Jan 2, 1915

By Abhilash

Different methods of utilizing refractory bauxite and disposing red mud are practiced throughout the world, but none of them are known to be environmentally innocuous due to the complexity and /or high cost, and none has been found to be feasible on an industrial scale. Under these conditions, the use of bioleaching process seems promising. The present study emphasizes on the isolation of native extremophiles from the source Indian bauxite and red mud, with their detailed cellular and physio-chemical, and biochemical characterization. These organisms were tested for their ability to thrive in physically or geochemically extreme conditions. The gram positive capsule rich mesophiles and thermophiles were tested for removal of gangue minerals from the bauxite and red mud samples. Keywords: refractory bauxite, red mud, extremophiles, bio-beneficiation, gangue

Sep 1, 2012

By Marie Farnsworth

"The Anhydrite ProblemThe Nonmetallic Minerals Experiment station of the Bureau of Mines at Rutgers University, New Brunswick, N. J. has recently undertaken a study of the chemical and physical properties of anhydrite having in view its wider utilization anhydrite (CaSO4) in contact with water at ordinary temperature and pressure rehydrates, slowly forming gypsum (CaSO4.2H42O). In nature this is an extremely slow process, and laboratory experiments are being conducted to determine methods of accelerating the rehydration. The tests recorded herein cover one this study, and while they are negative in character in so far as the major problem is concerned, certain facts established by the tests, bearing on the stability relations of gypsum and anhydrite seem sufficiently important to be placed on record.Early Researches on Gypsum and Anhydrite.It is to Lavoisiar that we are the first scientific study of the calculation and hardening of plaster of Paris. He sums up his experiments in the following passage: ""If gypsum, which has been deprived of its water of by means of heat, is again treated with water (to make what is commonly called mortar) it takes it up with avidity, rapid and irregular crystallization occurs, and the small crystals which are formed are so entangled in each other that a very hard mass results."" Later, he observed that the dehydration of gypsum occurs in two stages: three-fourths of the combined water is much more easily driven out than the last fourth. LeChatalier first determined the temperature decomposition accurately, his method was as follows: Pulverized gypsum was placed in a glass tube in the middle of a paraffin bath, the temperature of which was raised in a progressive and regular manner. A thermometer gave at each instant the temperature the salt, and the passage of the mercury column past each division of —co. was cared by a registering chronograph. The rise in temperature was except at 128°C. and 168°C. where breaks occurred."

Nov 1, 1924

By C. W. Goodale

THE motives behind the organization of the Bureau of Safety were twofold. First, there was the policy of the company toward its employees, which was one of fairness and consideration for their welfare and which entails the prevention of injuries; second, in order to prevent injuries, a study of their causes was essential, and this study could be made only by a thorough systematic classification of accidents, which required a special department to form and carry out the plans. The Bureau of Safety was organized to begin operation Jan. 1, 1914, but practically all of the first year was spent in collecting data, making plans, etc. This department is semi-independent of others and reports directly to the president and general manager. It consists of the president of the company and the managers of the following departments: Mines, Washoe Reduction Works, Great Falls Reduction Works, Coal Department, Lumber Department, B. A. & P. railway, and the chairman of the Bureau of Safety. Working under this group is the General Safety Committee consisting of the manager of mines, as chairman, the general superintendent, two assistant general superintendents, and the heads of the following departments: mechanical, geological, purchasing, sampling works, and framing plant, as well as the safety engineer. Operating under the General Safety Committee are the group safety committees, consisting of the Anaconda group of mines, Boston & Montana group of mines, zinc group of mines,.Washoe reduction works at Anaconda, B. & M. reduction works at Great Falls, coal department, lumber department and the B. A. & P. railway. Each of these group safety committees was in charge of the superintendent or manager of the group represented and the committee consisted of the foremen of the mines or works that the committee served, as well as the safety engineer.

Jan 2, 1922

By J. Botula

In the region of the North-Bohemian Coal Basin and its environment, there, in a row of places, are found the accumulations of rocks of the sedimentary and pyro clastic origin, the preliminary composition of those shows the possibility of their being utilized for the production of ecologically sparing natural Fe- and Ti- pigments and filling substances. In many places of the regions of Chomutov and Podborany and near Bilina and also in other places, there are found raw stocks perspective for the preparation of yellow up to ochre-brown, red, brown-red and green dyes. The target of project is the verification of dispensable reserves, their mineralogical composition and chemical and physical attributes, verification of treatment ways of Fe-and Ti-pigments separation (hydrocyclones, magnetic and electrostatic separation) and their stabilization and technological painting attributes for applications in colors, coating and plastic masses, mortar mixtures etc.

Jan 1, 2014