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By H. G. Iverson

Solid state reactions of manganese with silica were investigated in high-temperature tests. Reactions of 0.5 to 4.0 moles manganese (Mn) with 1 mole silica (SiO2) at 1,100° C and of 2.0 Mn:SiO2 mole-ratio mixtures at 1,000° to 1,150° C yielded products consisting of a slag phase and a metallic phase. At 1,100° C, the slag phase from reactions of the low Mn:SiO2 mole-ratio mixtures was composed of SiO2 and rhodonite (MnSiO3), and the slag phase from the high Mn:SiO2 mixtures was composed of MnSiOs and tephroite (Mn2SiO4). The metallic phase from the corresponding low Mn:SiO2 mole-ratio reactants consisted of two manganese silicides, Mn5Si3 and Mn3Si; from the high Mn:SiOg mixtures, it was Mn and the manganese silicide (Mn5Si). For the higher mole ratios of MnSiO2 the manganese content in the metallic phase increased, while the manganese and silica contents of the slag phase remained nearly constant. The slags did not contain free or uncombined manganese oxide (MuO). For the 2.5 to 4.0 Mn:SiO2 mole-ratio mixtures reacted at 1,100° C, the maximum quantities of silica reduced and of the manganese in the slag appeared to become asymptotical at about 41 and 48 percent, respectively. A brominating procedure was developed that was highly selective in removing the metallic constituents from the reaction product, leaving the slag phase as residue. X-ray diffraction patterns were obtained on prepared silicides Mn5Si, Mn3Si, and MnSi.

Jan 1, 1967

By D. Hinton, M. McCawley, R. C. Lantz, F. Pisano, C. Stanley

"INTRODUCTION Aerosols (5 um have not been shown to be consistently generated and characterized in inhalation chambers. Particle deposition in the lungs however may occur with particles as large as 25 um(1). Therefore, in order to closely simulate the atmosphere of an underground coal mine where the distribution is bimodal, with modes at S and 15 um (2), particles much greater than <1 um must be characterized for uniform mixing and size distribution within these chambers. The Hazelton Animal Exposure Chamber has been chosen because it has been best characterized for smaller particles (<1 um) (3), and is the major type used by most inhalation toxicology institutes such as Lovelace Inhalation Toxicology Institute and Battelle Northwest Laboratory.BACKGROUNDPreviously published studies on the inhalation of solid aerosols have attempted to characterize the distrition of particles of <2 um in diameter. There are no published reports of extensive work characterizing either the size distribution of particles <1 um or the concentration throughout the exposure chamber (Table 1).Table 1 shows the variability and sizes of several aerosols <1 um in diameter used in five previous chamber studies.Discussion of Previous StudiesThe study done by Bauermash, Bryan, Dickinson, and Burke (4)stated two major concerns in the development of the 6.5 ft. diameter chamber. The first was that a quantity of animals could be exposed to the same concentration regardless of the location of the animal, and second was that the chamber could be easily cleaned and decontaminated. The solution to the first concern required a circular chamber with the contamination air entering the chamber somewhere along the central axis. The animals could then be changed during exposure time so that each animal was exposed throughout the total volume."

Jun 1, 1988

By Edmund Shaw

This paper is one of a series being prepared by the United states Bureau of Mines describing mining and milling methods and costs at industrial mineral plants throughout the United states. These papers are designed to disseminate technical information regarding the methods and equipment used. The cost tabulations represent operating expenditures only and not total production costs. It is recognized that publication of total production costs might, in many instances, cause embarrassment to individual producers as well as to the industry as a whole. On the other hand, operating costs are essential to the technical discussion and study of the methods employed. The attention&apos; of the reader? is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulations shall ensue. P. J. Weisel, Inc., with office at La Habra and plant at Corona, Calif., is the only local company that produces sand for the Los Angeles glass factories, although silica sand for other purposes is produced in other parts of southern California and the adjacent portions of Nevada. The deposit at Corona consists of coarse sand imbedded in a whitish clay and differs greatly from the other deposits, which are fine-grained sandstone that must be crushed before it can be screened and washed. The preparation of Corona sand has to be thorough and includes grinding in tube mills, repeated washing and rinsing, removal of dust by air separation, and magnetic separation of iron and other minerals. This requires a plant with a complicated flow sheet. The first plant built did not make a. satisfactory glass sand, and many additions and changes were necessary. It is thought that the present flow sheet will remain substantially unchanged until a new plant is built. The design of a new plant would be simpler, but the process would be the same.

Jan 1, 1937

By J. H. East

"INTRODUCTION .Very little information regarding coal mining in Spain has been published in the American technical press, and few people realize the extent of this industry or the conditions under which coal is mined. The information in this publication was collected in 1945 and consists of personal observations in Spain, statistics, and other data of a, general nature obtained from official sources.Spain produces bituminous coal, lignite and anthracite, but the total tonnage mined is less than the national requirements. Before the war, an appreciable tonnages coal was imported from Great Britain under the Anglo-Spanish treaty, which rebated import duties and effectually prevented competition from any other foreign source. The war stopped the major part of the important of British coal and caused rapid expansion of the domestic sources, but this was not sufficient to supply the industrial demand. Coal that formerly was not acceptable to industry because of quality is now mined and marketed. The Government, allocates the better-grade bituininous coal to the various industries in accordance with the national importance of the work in which they are engaged; for example, the railroads are allotted 100 percent of their requirements, but cement companies can obtain only 25 percent.The Government offered to inducements to increase the production of coal of any class, but the larger part of the increased tonnage obtained was in inferior grades; as a result, the lignite production was taxed, while a bonus was paid for bituminous-coal production in excess of the 1942 tonnage.The anthracite and bituminous-coal areas were severely damaged during the Civil War and many experienced miners migrated to the lignite mines in eastern Spain. This has resulted in an acute shortage, particularly the Province of Oviedo where the most important bituminous-coal deposits are located."

Jan 1, 1947

By Harry W. Campbell

In 1984 and 1985, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied part of the Meadow Valley Range Wilderness Study Area (NV-050-156) in order to evaluate its identified mineral resources. The study area is located in Clark and Lincoln Counties, NV, about 50 miles northeast of Las Vegas, NV. The Johnston and Fitchett prospect, in the northern part of the study area, has more than 3 million tons of marginal perlite reserves suitable for many commercial uses. A preliminary mining feasibility estimate suggests perlite could be profitably mined from the study area; however, it is unlikely these perlite deposits will be developed in the foreseeable future because of unfavorable market conditions. Zeolite minerals occur in alteration zones adjacent to perlite deposits at the Johnston and Fitchett prospect, but high quality material is closer to potential markets. A metalliferous black shale unit containing 800,000 tons of subeconomic resources may extend into the study area at the Bradshaw vanadium prospect on the northwest boundary. Limestone, stone, sand, and gravel occurrences are wide-spread, but other suitable deposits in the region are more accessible to potential markets. Seven prospects in and near the study area were examined. The entire study area is leased for oil and gas exploration. A group of perlite placer claims covering more than 480 acres was located in the 1940&apos;s in the northern part of the study area. A small group of lode claims was located in the mid 1950&apos;s in the southwest part of the study area. No mining claims are currently (1985) held inside the study area. No mineral production is known from within the study area.

Jan 1, 1987

By T. OnIin, F. F. ApIan

"A study has been made of the surface properties of coals of differing ranks, in their natural state and as modified by the addition of collectors. The evaluation of their surface properties has been done by captive bubble contact angles, water and methylene iodide sessile drop contact angles, zeta potential, point-of-zero charge (PZC) shift, and flotation. .changes in the hydrophobicity of coal is a function of both the rank of the coal and the collecting reagent.INTRODUCTIONThe chemical and physical properties of a raw coal will determine its response to a given beneficiation process. .For such processes as flotation, filtration, flocculation, dispersion, handling, dust supression and agglomeration, however, it is also necessary to consider the surface properties of the coal and mineral matter constitutents of the raw coal. In the case of a specific particle to be floated, it is also necessary to consider the properties of the coal as modified by the addition of some reagent designed to modify (usually increase) the hydrophobicity of the coal surface. General properties of the coal have been well summarized by Van Krevelen (1) and Elliott (2), while the data for the surface properties of coal are much more scattered in the literature (see, e.g.: Parekh and Aplan (3), Gutierrez-Rodrigues et al. (4), Aplan (5), Arnold and Aplan (6), Hogg and Chander (7) and Rosenbaum and Fuerstenau (8)). While a knowledge of the inherent surface properties of a sample are important, of much greater practical significance are the properties of the particle in the presence of a reagent, such as a collector, designed to enhance the hydrophobicity of the particle. This study will focus on the surface properties of coals of various ranks in the presence of a variety of collectors."

Jan 1, 1989

By Manuel Gomez

This report presents low-temperature tar data from studies by the Bureau of Mines of tars produced in an externally heated (entrained state) pilot-plant-scale retort. Analytical data covering 20 low-temperature tars, derived from the. carbonization of various ranks of foreign and domestic coals, are tabulated. The character of the tar is discussed in relationship to carbonizing conditions and the rank of coal. It is seen that in carbonization techniques that employ entrainment or fluidization of the coal particle, carbonization conditions are secondary to coal rank with respect to tar-oil yields and composition. The influence of distillation conditions on recoverable yields of tar products is presented. The probable yield of commercially important chemical products, based on a ton of pure (moisture- and ash-free) coal, are predicted. INTRODUCTION Low-temperature tars produced by entrainment or fluidized carbonization techniques that employ internally heated reactors represent the most nearly primary tart produced by industrial processes. In brief, such a process involves the application of a heat gradient to the coal particle "boiling" or suspended in a turbulent state in the reactor chamber. Conditions are observed so that the coal particle remains suspended within the reaction zone by a gas stream for a time interval commensurate with maximum tar-oil yield. The heat necessary for the carbonization reaction may be obtained entirely from the hot (preheated) gas stream, or it may be derived partly from the combustion of the volatile products and char by the transport gases, usually air. The volatile material moves out of the carbonizing zone at a rate that approaches the velocity of the transport gas. Carbonizing conditions are ideal when a minimum particle residence time is obtained within the reactor at a given temperature and a maximum yield of condensable volatile matter is released. In industrial practice this objective is a compromise.

Jan 1, 1957

By J. W. Griflith, P. A. Mack, C. M. Lang, S. Riling

"N-acetyl-beta(B)-D-glucosaminidase is a N-acetyl-beta((B)-D-glucosaminidase enzyme se¬creted by alveolar macrophages in response to phagocytosis of particulate material. Alveolar macrophages participate in the degradation and fibrosis of pulmonary tissue that results in pneumoconiosis. Known quantities of four characterized respirable dusts were bronchoscopically placed into the right caudal lung lobe of macaque monkeys. Bronchoalveolar lavage (BAL) samples were collected from dust-exposed right lung and unexposed left lung of the same individuals at 2-week intervals for 12 weeks after dust instillation. The samples were tested for N-acetyl-B-D-glucosaminidase activity to determine if the enzyme levels could serve as an indicator of pulmonary injury induced by generic coal dusts when compared to known fibrogenic and nuisance dusts. Installation of generic quartz, anthracite, or TiO2 dusts produced significant elevations of enzyme activity and increased numbers of macrophages in the dust-exposed lobes. Elevations in enzymatic activity and macrophage numbers were greatest in response to generic quartz dust. These results suggest that quantitative levels of N-acetyl-B-D-glucosaminidase activity may be a useful indicator of acute and chronic lung injury following exposure to fibrogenic and nonfibrogenic dusts.IntroductionCoal workers pneumoconiosis (CWP) is an occupational pulmonary disease associated with the inhalation of coal mine dust. An important external factor in the development of CWP is the composition of the respirable coal mine dust. A cause-and-effect relationship exists between coal mine dust and CWP, but it has not been shown that exposure to generic coal dusts will cause CWP [12]. Numerous immunological, biochemical, and cellular changes occur in CWP; however, in this study, only N-acetyl-beta(B)-D-glucosaminidase (NAGase), protein, and alveolar macrophages (AM) will be examined [7, 32, 33]."

Dec 1, 1996

By J. E. Tiffany

Some of the gases produced by permissible explosives on detonation are poisonous, and the probable hazard involved by the inhalation of carbon monoxide in the past has been evaluated from results of tests in the Bichel Gage. Tests have now been made in the Experimental Coal Mine of the Bureau of Mines at Bruceton, Pa., to determine the composition of the gases obtained under actual mining conditions for the purpose of comparing these, results with those found by the Bichel gage tests. Two permissible explosives were procured for these tests, one that produces a relatively low quantity of poisonous gases in the Bichel gage (24.8 liters per 1-1/2 pounds of explosive) and another that produces a relatively high quantity of poisonous gases (94.6 liters per 1-1/2 pounds). The first of these is designated by the Bureau of Mines as a class A4/ explosive and the other is designated a class B explosive. In comparison with Bichel-gage tests, the shooting of permissible explosives in a coal shot hole resulted in a large reduction in the quantity of carbon monoxide, the principal poisonous gas, which; in the mine tests, was only 22 percent of that found in Bichel-gage tests: The quantity of carbon monoxide from the class B explosive in Bichel-gage tests was 3.8 times larger than that from the class A explosive; in the coalmine tests the ratio was 4:1. The concentrations of carbon monoxide in the mine tests, as determined by analysis of the atmosphere in an enclosed space resulting from shooting 1-1/2-pound and 3-pound charges of the class A explosive, were 0.03 and 0.06 percent, respectively, and the concentrations from 1-1/2-pound and 3-pound charges of the class B explosive were 0.10 and 0.24 percent.

Jan 1, 1950

By W. A. McKinney

Bureau of Mines Research has demonstrated that it is technically feasible to segregate oxidized copper ores by use of a direct-fired, refractory-lined rotary kiln. Previously, the segregation process had been effected only in much more complicated indirect-fired, stainless steel kilns, The method comprises heating crushed ore premixed with small quantities of salt and carbonaceous material, such as coke, to about 830° C to produce copper as fine flake and metallic films on the surface of the coke particles. After grinding of the cooled furnace calcines, the copper is recovered by conventional flotation. During direct-fired segregation it was necessary to closely control the air-gas mixture in the burner. Good copper recoveries were obtained only when adding air in the limited range of 1.15 to 1.2 times the theoretical amount required for combustion of the natural gas. Batch trials of the new technique on quartzite-, limestone-, sandstone-, and limonite-type oxidized copper ores containing from 1.4 to 6.2 percent copper yielded flotation concentrates containing from 3.7 to 45 percent copper, representing 84 to 95 percent recoveries. Analyses of the furnace gases showed that loss of copper by volatilization was negligible. The preliminary direct-firing segregation studies were complemented by continuous runs on the quartzite ore, containing 1.4 percent copper, in an integrated segregation-flotation pilot plant having a 60 pound-per-hour capacity. In a typical test, 84 percent of the copper was recovered in a cleaner flotation product containing 25 percent copper. The study will be continued to further delineate the conditions for good segregation as effective use of standard ceramic-lined kilns will render the process more attractive from a commercial standpoint.

Jan 1, 1963

By C. H. Riggs

"INTRODUCTION The injection of gas into the McClosky limestone in the adjoining, Griffin and New Harmony field in Indiana and Illinois and resulting increases in oil and gas production from this zone ore described in this report.Since 1911, the use of compressed air or as to increase oil production by supplementing natural reservoir energy has been widely adopted, and has resulted in the recovery of much additional oil, which otherwise would have been left underground. In many of the newer oil fields, including Griffin and New Harmony, a part of the compressed residue gas from natural gasoline plants is returned to the reservoir as a secondary method to increase oil and gasoline production. Part of the injected gas is stored underground for future use.By presenting data on many secondary recovery operations in a series of reports 5-9/ the Bureau of Mines has sought to stimulate interest in secondary recovery as a means of increasing oil recovery and current oil production for wartime needs. Most of the elder fields in the United States produce oil from sandstone reservoirs, and probably more than 90 percent of secondary recovery operations have been developed in oil bearing sandstones. During recent years, the volume of oil obtained by primary methods from limestone reservoirs has increased steadily, but as yet little has been done to recover, by secondary means,,the large volumes of oil left in limestone reservoirs when primary methods production are no longer profitable. Because of inherent differences in the origin and nature of the pore spaces between sandstones and limestones and because of differences in permeability and fluid content, secondary recovery methods, which are successful in sandstone-reservoirs, are not always applicable to limestones. Not much he been written concerning secondary recovery operations in limestone reservoirs, and few data are available to assist operators in developing such secondary recovery projects."

Jul 1, 1945

By R. R. Sayers

Mine operators and managers for a number of years have known that the maintenance of health among the workers has an appreciable financial value, In order to maintain the health, it has been found ne cessery to imow; 1. The health hazards existing in the industry as a whole and the specific hazard in the individual mine. 2. The physical condition of applicants for employment as well as that of the old employees. This can be determined only by systematic physical examination of all applicants and of regular employees at intervals of at least once a year thereafter. 3. All cases of sickness that occur among the workers. No operator or manager, or personnel, medical, or safety organization can control or prevent sickness without knowing where, when, and under what conditions the sickness actually occurs. In order to obtain information as to the hazards of industry, investigations have been and are being made of the effects of the condi- tions both in the field under usual working practices and in the laboratory. In the field several factors are generally present which affect the health. The effect of these factors may be determined by studying each of them separately in the laboratory. However, both the field and the laboratory studies are limited in value in that such studies usually have been made over a comparatively short period. While we have some information as to their immediate effect, we do not know to what extent extreme heat, humidity, the presence of dust or other health hazards are the cause of disability. Mortality statistics are probably the most easily available indices as to the hazards of industry. As an example, a study of such statistics among coal miners of Indiana shows a marked increase in the death rate in 1918.

Mar 1, 1923

By R. R. Sayars

"Carbon monoxide is a gas slightly lighter than air, with which it diffuses readily to make a homogeneous mixture. It will burn and has a wide explosive range, that is, an explosion is possible when the air contains from 15 to 73 per cent of the gas3. This explosive range is about the same as that for hydrogen and over nine times As Tide as that for marsh gas (methane). Like air, it has neither color nor taste and has no odor in concentrations usually encountered, therefore it cannot be detected by the ordinary senses with which men are endowed. It is produced by burning carbon containing fuels, no coal, wood, gasoline, etc., whenever not enough air or oxygen is supplied to burn and oxidize the fuel completely.The human race has probably been exposed to this gas since men first began using fires in confined or sheltered places. The poisoning as usually encountered is an acute condition resulting from breathing atmospheres con¬taining this gas. A number of eases described in the ancient literature Indicate that carbon monoxide was a frequent cause of death by accident, suicide and is a means of punishment or torture. A quotation by Lewin from Aristotle who lived in 384-322 B.C., states that ""animals collapse from harmful odors as men gets a severe headache and often dies through charcoal vapors"". The Roman knew that smoke was poisonous, and used the greenest most smoke-producing wood to put persons to death. The occurrence of carbon monoxide increased in frequency through the years until at the present time it is found in the home as well as in many industries. The following table gives the approximate percentage of carbon monoxide found in gases from various sources of poisoning.4"

Apr 1, 1924

By Wilbert J. Huff, Raymond H. Moore

"Black powder is employed widely in peace and war. Its properties are therefore of considerable interest to many. The Bureau of Mines frequently is asked to furnish information on its use and safe handling in the mining and mineral industries in times of peace and is now engaged in studies of its application to the arts of war.Black powder has been the agent in many accidents - some very disastrous - and its handling and use are deemed very hazardous. The belief is widespread that the hazards are due principally to the ease with which the powder is ignited by a hot spark or flame in contradistinction to high explosives; these usually are ignited only with difficulty, and some burn incompl0tely and to a certain extent are self-extinguishing. Primary precautions, .therefore, should be taken to prevent the access of heat, spark, and flame.In black powder manufacturing operations a frequent source of disaster is the initiation of fires and explosions in the wheel mills in which the sulfur, charcoal, and nitrate are incorporated. Long experience has indicated that the wheel mill probably will fire if the powder is not kept moist enough; manufacturing supervision calls for the maintenance of a minimum moisture content, at least during the milling. Accidents occur elsewhere in the manufacturing line, and in an endeavor to minimize these, particularly those happening in corning mills, one of the writers suggested many years ago that a suitable humidity be maintained in other operations in the hope that it would serve protectively as in the wheel mill. The experience of one company for many years with this practice was favorable. It seemed desirable therefore, to explore the question experimentally."

Nov 1, 1944

"For a good many years the Bureau of Mines and various state mining experi¬ment stations have endeavored to develop some method of utilizing the immense deposits of lignite in the United States. Work in relent year has indicated that the best method of this is to drive off the moisture and most of the volatile water from the lignite in some form of carbonizing apparatus leaving a residue high in fixed carbon and low in moisture and volatile matter, which by briquetting can be made into a high-grade fuel. The earlier forms of carbonizing equipment tried were complicated, costly to build and keep in repair, and could not be operated intermittently without being seriously damaged. During the year 1922, however the Bureau of Mines devised a very simple carbonizing oven which produces a uniformly well carbonized product. This oven is essentially a vertical shaft with means for supplying raw lignite at the top and discharging the carbonized limited at the lower end. Air in regulated amount is admitted to the shaft at two horizons, and a zone of combustion maintained through which the column of lignite passes. The lignite is thus carbonized by construction of its contained matter and a small proportion of its fixed carbon, leaving most of the fixed carbon in the carbonized product or ""char"". The degree of carbonization can be closely controlled by varying the volume of air supplied to the oven and the rate of travel of the charre down the shaft.The ""lignite char"" produced is a soft material resembling charcoal more than coal or coke, but somewhat harder than charcoal. A typical analysis is shown in the table headed ""Fuels,"" further on in this papers."

Feb 1, 1924

By J. H. Wiggins

"The tests described below were conducted by the Bureau of Mines at a lease in Oklahoma on installations designed to decrease evaporation losses of crude oil Pram storage tanks. Use of the lease was granted by the Oklahoma Producing and Refining Corporation of America. Tankage was obtained through the courtesy of the Parkensburg Pig and Reel Co. The purpose of the installations and tests was to demonstrate the value of making crude-oil storage tanks gas-tight, rather than to determine the amount of evaporation in any one type of tank. None of the tanks used were absolutely gas-tight, but one of them was very nearly so. They comprised a tank of the ordinary open type with an 18-inch manhole, a tank with a ""4-inch vent"", a tank with a ""smaller vent"", and a tank which had only ""pin holes"" through which air and vapor could pass freely. On the last two tanks any excess pressure was taken care of by an automatic differential pressure regulator.The results obtained in these tests indicate that tight tankage will soon pay for itself. They will not, however, serve as a basis on which a producer can compute the actual number of days necessary for tight tankage to pay out, because the oil used was exceptionally volatile. It is probable that the average evaporation loss in the Mid-Continent field is at least one-half as great as that shown by these tests, and if this is true, the saving that would be effected by providing tight tankage on the lease will undoubtedly justify the expense. The installation of evaporation-proof tanks on the lease has been delayed by the failure of production managers to realize, first, that their evaporation losses are enormous, and, second, that they can practically eliminate these losses by a simple and inexpensive installation."

Apr 1, 1921

By Miller, ALEX U, Edward Thomas

In March 1937 the entire country was shocked by news of an explosion of gas in a New London (Tex.) schoolhouse, which resulted in the death of 280 pupils and 14 t eachers. The Government investigators of this disaster believed that the cause was the ignition and explosion of a large volume of explosive natural gas-air mixture that had accumulated in a poorly ventilated space beneath the first floor of the main school building and that this accumulation was due to leakage from gas lin suspended underneath the floor to carry the gas supply to the school.!i/ For some years there has been a potential explosion hazard in school houses and other buildings that are supplied with water from deep wells in certain parts of Illinois. Notwi thstand.ing the disaster at New London, Tex., and the fact that there had been gas ignitions at four water wells in different parts of the State, the explosion hazard in schools and other buildings was not fully recognized until a few months after the disaster in Texas, when an explosion occurred in the settling basin of the municipal water works of Clinton, Ill., and another in a pump house of the municipal water works in Normal, Ill, The explosion in the settling tank of the municipal water works in Clinton, Ill., occurred on August 12, 1937, and a.id considerable damage to the settling tank, but fortunately no one was injured. At the time of this explosion rapairs'and aJ.terations to the water plant were in progress, and 10 men were employed in the immediate vicinity of the settling tank. Two of these men were enlarging a hole in the concrete side with an air hammer for the installation of a larger discharge line.

Aug 1, 1938

By J. W. Hunter, J. H. Jacobs

"Approximately 355 tons of nodules from Chamberlain; S. D., ore were processed in the 1-ton-per-day electrolytic-manganese pilot plant of the Bureau of lanes at Boulder City, Nev., in a continuous 3-month operation. The ore, ground to minus 48-mesh, was found to be amenable to leaching with acid directly or after roasting under reducing conditions in a Skinner muffled multiple-hearth furnace.Unroasted ore gave an acid-leach extraction of 84 to 88 percent of the manganese, which after neutralization showed an over-all extraction of between 81 and 85 percent of the manganese. The amount of iron extracted varied, but it was always,enough to permit the use of ammonia for neutralization.Roasted ore showed an acid-leach extraction of 89 to 91 percent of the manganese. A large amount of iron went-into solution, so that it was not economical to neutralize it entirely with ammonia. By neutralizing with calcine to a pH of 5.0 and completing -neutralization with ammonia to a pH of a.5 an over-all manganese extraction of 84 to 86 percent was obtained. The slight increase in. extraction on roasted ore probably would not justify the cost of roasting.Acid consumption averaged 1.75 pounds per pound of manganese extracted. Settling rates of the residue in leach solution were to slow to permit clarification in thickeners, but a Moore vacuum leaf filter proved to be satisfactory. Purification of raw leach solution was .accomplished readily by hydrogen sulfide with a low gas consumption. Electrolysis was normal, without difficulty, and with -current efficiency ranging between 62 and 66 percent.The use of Chamberlain modules for the production of electrolytic manganese would result in an operating cost of 0.8316 cent per pound higher than the cost of producing electrolytic manganese from Three Wids ore."

Mar 1, 1946

By B. K. Shibler, K. C. Vincent, W. W. Agey

"INTRODUCTION As a part of the investigation of domestic manganese deposits, examining engineers of the Bureau of Mines collected samples of ore from three from three properties in the general vicinity of Tracy, Calif.The Buckeye mine is 23 miles of Tracy, just inside the northeast boundary of Stanislaus County. The mine is owned by K.O. Winship estate of San Francisco and is leased by Verner Allen, also of San Francisco.The ore is principally manganese carbonate occurring in interbedded layers in white chert, with the original,carbonate mineral altered in place. Four samples, representing four types of ore, were submitted, as follows: A, black oxide; B, pink carbonate; C, gray carbonate.The Wilfred Murphy property (also known as the Murmac claims) is approximately 30 airline miles south of Tracy. The property can be reached by road from either Livermore or Patterson and is on the divide separating Santa Clara and Stanislaua Counties Calif. The ore occurs in lenses along a white-chert formation. A 2-ton sample of ore for testing was taken from a dump accumulated from assessment and development work. The Ladd mine, 13 miles from Tracy in San Joaquin County is owned by Pat J. Connolly of Tracy and is leased by Mack C. Lake of San Francisco. The ore is essentially a chert impregnated with manganese oxides and the association is therefore exceedingly intimate and complex. Samples from each of the three adit levels of the mine were submitted for ore-dressing study.As the samples differed widely in physical character and response to ore-dressing methods of treatment, beneficiation of ores from each property was considered as a separate problem. Hence results of the investigations will be prescribed in separate sections of this report."

Nov 1, 1947

By D. Harrington, M. W. Von Bernewitz

Sections 120 and 121 of Article XI. Fire Control, of a proposed Mine Safety Law in preparation, to be used as desired and when approved by any State, contains these provisions: After the adoption of these regulations, no mine operator shall erect any nonfireproof structure within 50 feet of any mine entrance. or airway. Every operating mine having nonfireproof structures within 50 feet of any mine entrance or airway, except headframes necessary for hoisting, shall have such structures fireproofed or removed and replaced with fireproof structures within six months of the adoption of these regulations. Before reopening, mines idle at the time of the adoption of these regulations shall have all non- fireproof structures fireproofed, removed, or replaced with fire- proof structures as required by the foregoing sentence. Upon receipt of the written statement of a mine operator that the fireproofing of existing structures is impracticable, the chief mining engineer (of the State commission) shall satisfy himself as to the abouracy of the statement. If he concurs that fireproofing is impracticable, and if at the same time he holds the opinion that adequate protection can be provided otherwise by such procedure, he shall have authority to issue a written permit for the substitution of fireproof door at or near portals of mine openings and collars: of shafts. Such doors shall fit as nearly gas-tight as possible. and shall be installed in such a way that the mouths of mine open- ings can be closed readily from outside of structures. The effec- tiveness of such permit may be made contingent upon the operator's continued compliance with any additional precautions which are necessary in the chief mining engineer's opinion to protect the lives of miners.

Mar 1, 1932