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By Hani Henein

Recent innovations in atomization of molten metals have occurred in the area of single fluid atomization. Impulse Atomization (IA), one of the single fluid techniques, provides unique capabilities to study different regimes of atomization in a controlled environment. By changing processing variables, a mono-dispersed distribution of droplets above one millimeter in diameter can be produced. This is accomplished through proper characterization of the forces influencing the process and in particular the flow of melt through the orifice. This paper will discuss the approach and illustrate results with molten aluminum and cobalt.

Jan 1, 2006

By J. T. Popp

This Bureau of Mines study reviews the geological factors that affect methane in the Beckley coalbed in southern West Virginia, including overburden, coalbed structure, type of and changes in lithology above and below the Beckley coalbed, and presence of fractures in the coal and rock adjacent to the Beckley. Depending on the depth, the Beckley coalbed emits from 216 to 520 ft3 of methane per ton of coal mined, and the Bureau estimates that methane emission in a deep, extensively developed mine in this area may exceed 3,000 ft3 per day per ton of coal mined. Average face cleat and butt cleat trends in the Beckley coalbed measured underground are N 33° W and N 53° E, respectively. Close cleat spacing con¬tributes to the friable nature of the Beckley and provides easy movement for methane and water. Because rider coals, splits, and carbonaceous shales may contribute methane to mine emissions, predictions of methane emission based on gas content of the Beckley coalbed alone may be conservative. Beckley coalbed reserves in the study area are 234 million tons. The gas content of the Beckley coalbed averages 407 ft3/ton, and the coalbed gas reserves are 108 billion ft3.

Jan 1, 1976

By John C. Holtz

Information on the gaseous products from the detonation of explosives has been obtained in two ways. In the first, the atmosphere in mines is analyzed after blasting, aid in the second, the gases found after detonating an explosive in a testing apparatus are analyzed. The Bureau of Mines, in

Jan 1, 1940

By Claude Deveau, Stephen R. Young

Introduction Tanco History Tanco is sometimes known as the Bernic Lake Mine. It is located about 180 km east-northeast of Winnipeg close to the Manitoba-Ontario boundary. Tanco operates an underground mine employing ramp access, room and pillar mining and shaft hoisting for the production of tantalum, lithium and cesium minerals. Tantalum recovery employs conventional gravity and centrifugal concentration methods along with a flotation process which recovers ultra-fine tantalum. All tantalum concentrates are shipped to Cabot Supermetals, Boyertown, Pa., for the production of tantalum chemicals and metals. Tanco also produces lithium products from spodumene ore. The lithium concentrates from Tanco are shipped worldwide for use in ceramics, specialty glass and mold powders. Cesium processing involves the dry grinding of pollucite as feed stock to the on-site chemical plant dedicated to the production of cesium formate, a high density drilling fluid. Tantalum milling operations commenced in 1969. In the early years of the operation, feed grades were three to four times as high as they are today. Coarse-grained tantalum mineralization with complete tantalum liberation at sizes of 300 µm allowed for easy recovery with conventional equipment such as spirals and shaking tables. Over the years, the process and feed material to the plant have drastically changed. Due to drastically reduced liberation sizes, efforts have been made to try to recover as much of the liberated particles as possible in order to maintain acceptable recoveries.

Jan 1, 2005

By József Faitli, Barnabás Csoke, Károly Solymár, Zoltán Hatvani, Dimitri Papanastassiou

In most cases, the sizing of dry or wet mills for ore processing is primarily based on the determination of the Bond grindability index, using the Bond-Kjos-Rowland relations. In several cases, grinding takes place under conditions different from these and the grinding conditions have a great influence on the postgrinding process. This is particularly true for the grinding of bauxites where grinding takes place in alkali, often in higher temperature in alkali Liquor. So it is necessary to develop a testing method providing a reliable grindability index even under these special circumstances and allowing a more precise mill sizing. Therefore we surrounded the grinding crucible of the Hardgrove mill with a crucible furnace to heat it. The new heated mill is suitable to determine the grindability index under temperature-controlled circumstances, in liquids (water and alkali) with different temperatures. The required heating power is 2000 W. In the implemented equipment we installed four 230V/500W electric heating wires made from heat-resistant alloyed material and surrounded by ceramic insulators. The temperature and temperature-gradient are measured by four PT100 platinum thermal resistors. The data acquisition and control program written in the C language in the Lab Windows CVI program environment measures the voltage proportional to the temperature. Determining the grindability indices of hungarian and greek bauxites experimentally, first dry grinding tests were carried out under standard conditions. During wet and alkaline grinding, to 50 g of dry bauxite 85.5 g of industrial alkali with a concentration of about 200 g/l was added. As grinding aid 2 g of CaO (4 % of dry bauxite) was dosed. From the data it can be concluded: - The tested bauxites show a similar behaviour against temperature change. However, the extent of grindability change is different for different bauxites. - Soft Hungarian boehmitic bauxite can be ground in a high-temperature alkaline medium better than hard Greek one. The increase of grindability according to the high-temperature Hardgrove indices: (kHT = Dry o HT,alkaline H /H ): for hard Greek and soft Hungarian boehmitic bauxites: kHT = 1.7 and 2.4 respectively; according to estimated Bond indices (kB,HT =Wi,dry/Wi,HT, alkaline ): kB,HT = 1.6 and 2.1. - The increase of grindability is the most important factor the reaction of kaolinite with caustic liquor and lime and the loosing of the textural structure at 80 ºC and especially at 100 ºC.

Jan 1, 2003

By Reynold Q. Shotts

A study was made of the coal resources of an area in Jackson County, Ala., forming a part of the Flat Rock, Henegar, and Stevenson quadrangles. The area studied is a portion of the Plateau coalfield on Sand Mountain and is near the Tennessee Valley Authority's Widows Creek steamplant. Since no detailed geological study of this area had been published, some reconnaissance work was done. The coalbeds and adjacent strata such as sandstones, conglomeratic sandstones, and conglomerates were studied. Available drill logs, together with the areal geology, provided sufficient information to permit correlation of the coalbeds and an estimation of coal reserves. For all categories of reserves, computed on a regional basis, a total of 72,920,000 tons of coal more than 14 inches thick is estimated for the areas studied in Stevenson. Flat Rock, and Henegar quadrangles. Of this tonnage, 40,001.000 tons is estimated to have less than 60 feet of overburden. The total measured coal reserves for the above three quadrangles are 16,359,000 tons, with 12,471,000 tons under less than 60 feet of cover.

Jan 1, 1966

By J. P. Sancho, J. M. Duart, J. I. Verdeja, J. O. García

Following a short review of the history of rails used in the transport of passengers and goods, this paper describes the process for rail fabrication, rail structure, and properties, and summarizes the fatigue test curves carried out on rails used today. Also reported is the process for “continuous rail” production using aluminothermic welding via the introduction of weld metal in onsite casting, as a homogeneous melt. Weld characteristics of aluminothermic welding using different preheating procedures—fusion zone, heat-affected zone, microstructure, hardness, slow bend test, and fatigue test resistance (Wöhler curves)—are related to preheating and welding procedures of 700, 900, and 1,100 MPA rail grades. The Locati method is preferred over the staircase method for ascertaining the fatigue limit due to its simplicity. Macrographic and metallographic inspection of broken specimens reveals the reliability of welding techniques and the good metallurgical quality of welds.

Jan 1, 2007

By Benoit Clermont, Jan Lux

"Magotteaux and Anglo Platinum started a co-operation program with the main aim of establishing the optimum milling configuration measured in terms of throughput, fineness and energy consumption.For this purpose, a fully instrumented pilot milling plant, supplied by Magotteaux (Pty) Ltd, and equipped with a 0.9 x 1.0 m ball mill, was erected at Frank concentrator (Merensky Pt ore). The primary ball mills at Frank concentrator were surveyed in order to set the conditions for the base case. This data was then replicated in the pilot mill under the same configuration. Thereafter, a series of different parameters were varied in order to attempt to optimize the milling system.Only grate versus overflow discharge and open versus closed circuit will be discussed in this paper.It should be noted that this paper does not attempt to give a universal solution as to what milling configuration is optimum in all cases. The conclusions apply for this particular case and probably most others, but it would be advisable to consider each case on its own.CONCLUSION• Overflow versus grate dischargeAn overflow mill has a “pool” of slurry around the toe of the ball charge, which creates a counter lever to the ball charge. This will reduce the absorbed power in the range of 10-15% (depending on the case) and will consequently result in a coarser grind. The tests found a 4% gain in grinding efficiency (Wio) with an overflow mill but this is probably not significant.This lower absorbed power and coarser grind can be counteracted by increasing the ball charge (if below maximum) and/or by increasing the mill volume when removing the grate discharge (a typical grate takes up about 300mm of the mill length).• Open versus closed circuit"

Jan 1, 2003

By Peter Dunn

London Mining Plc. is developing an iron ore project in Sierra Leone. The Marampa mine is a brownfield development effort, having been operated by others since the 1930?s until low iron ore prices forced closure. Peak production of the prior operations was approximately 2.5 Mt/a in the 1960?s. Following civil war In Sierra Leone, London Mining obtained the mining license in 2006 and commenced activity to redevelop the Marampa mining and processing operations. There are two ore deposits of interest for development as well as a resource comprised of tailings from previous operations. Phase 1 will be the mining of the tailings resource with a 1.8 Mt/a plant producing 66 per cent Fe sinter feed, expandable to 3.6 Mtpa. The first phase is currently under construction with start-up expected in the third quarter of 2011. Phase 2 will include development of the two ore deposits. These deposits are weathered secondary ore and the main primary ore resource. Phase 2 is currently under prefeasibility study and targets a final 16 Mt/a concentrate production in 2016. Outotec partnered with London Mining on testing efforts to develop the magnetic separation flowsheet using SLon VPHGMS machines to process the Marampa material. This paper explains the flowsheet development process for the weathered and primary ores commencing with sample characterization and detailed parametric investigations to evaluate SLon performance. The final flowsheet configuration is explained, including expected circuit recoveries and concentrate quality, clearly demonstrating the performance of the SLon VPHGMS circuit in iron ore tailings treatment applications.

May 1, 2011

By G. W. Jones

"INTRODUCTION In a previous reports results were given of a manhole investigation carried out over a period from June,- 1929, to July, 1930, in cooperation with the Edison Electric Illuminating Co. of Boston, Mass., to determine the general hazards of combustible gases and vapors in manholes and other underground openings owned by this company. Considerable time was spent in this initial investigation in developing a suitable detector for determining the range of explosibility of the gases found in manholes. About 17,000 tests have been made with the detector since the investigation was started and its utility has been verified and its accuracy checked, by having complete analyses made of such samples that showed combustibles present equal to or above 25 per cent of the lower explosive limit, and those found deficient in oxygen.The initial investigation made in 1929 and 1930 demonstrated that the detection, control, and elimination of combustible hazards in manholes can best be obtained by a close cooperation of the interested parties through a systematic and continuous inspection of manholes, under proper supervision.COOPERATIVE INVESTIGATI0N DURING 1931The investigation carried out during the year 1931 has been along lines similar to that conducted during 1929 and 1930. In the present investigation the Edison Electric Illuminating Cc. of Boston and the Boston Consolidated Gas Co., have cooperated with the Bureau of lanes. The Boston Consolidated Gas Co. serves a major part of the territory under discussion with gas, but the tests covered the Edison territory irrespective of the gam company furnishing manufactured gas. A test crew consisting of two men, one an employee of the Consolidated Gas Co. and one an employee of the Edison Electric Illuminating Co., has been continuously employed during the year in the testing of games in manholes served by the Edison system. The test crew was under the direct supervision of John Campbell, superintendent of the special service department of the Edison Electric Illuminating Co., and F. M. Goodwin vice president of the Consolidated Gas Co.As in the previous investigation, all manhole tests were given test numbers. The test data sheets on which the information regarding the tests were recorded were prepared in triplicate, one copy going to the Edison Company, one going to the Gas company, and the third to the Bureau of Mines at Pittsburgh. These test data sheets were then filed (1) according to the town, (2) the street location, and (3) the manhole number; in this way a complete record pf each manhole tested was immediately available. A specimen test sheet is given below."

Sep 1, 1932

By H. Lagendijk, I. J. Reinecke

Mintek was contracted by Oriel Resources plc in 2004 to conduct a preliminary assessment study on smelting ferronickel from the large but relatively low grade Shevchenko nickel ore deposit in Kazakhstan. A detailed feasibility study (?DFS?) was awarded to Bateman BV following promising results from the preliminary assessment study (?PAS?) and small-scale pilot plant test work. As part of the DFS, a total of 450metric tons of ore was collected from three different locations in the deposit and shipped to Mintek. After sampling, the bulk sample was prepared for smelting. This comprised crushing, screening and calcining with each step done separately for the three different lots. The chemical composition of the ore from the deposit is relatively high in silica and therefore falls out of the MgO to SiO2 range that is normally processed by pyrometallurgical means to produce ferronickel. The main objective of the testwork was to demonstrate that a method could be found and successfully applied to smelt these siliceous ores and produce an acceptable nickel-containing alloy. A 2-m ID DC arc furnace was installed with a twin-cathode (electrode) configuration to replicate the proposed commercial-scale furnace and also incorporated an advanced design of water-cooled copper panels in the lower furnace sidewalls to withstand the aggressive nature of the high SiO2-containing slags. The reductant used was a high-volatile coal from Karaganda in Kazakhstan. The reductant addition was adjusted to achieve a 90% recovery of nickel. In the assessment of the process metallurgy, some deviation from equilibrium conditions was observed. This deviation is ascribed to the intermittent existence of a smelting bath partially covered with feed during the testwork. Optimization of smelting conditions should result in the metallurgy (slag metal equilibrium) being closer to the theoretical predictions and make the production of a 20% nickel alloy possible at 90% nickel recovery. The solution for the successful processing of these siliceous ores was found in the attainment of the necessary operational stability through the control of arc length, operating temperature, open-bath smelting conditions and flux additions of up to 10% dolime for the most siliceous of the three ore types. The test work carried out by Mintek provided the basis for the process flow sheet and engineering design of the DC arc smelting furnaces for the Shevchenko Nickel project.

Jan 1, 2007

By William G. Szymczak

A set of experiments were conducted at the Aberdeen Proving Grounds [1] in which explosive charges were buried in saturated sand beneath a suspended rigid platform. The goal of these experiments was to measure the dependence of the impulse transmitted to the platform on the standoff distance and the charge burial depth. Simulations of these experiments were performed using the BUB2D axi-symmetric code using a frictional-cohesive visco-plastic model to describe the response of the saturated sand. This code solves a constrained set of conservation laws in which the liquid region (in this case saturated sand) is assumed incompressible. The explosion is initialized as a high pressure gas bubble (void) within the fluid. Comparisons of the simulations to the experiments are presented together with a study of the physical phenomenology associated with the loading process. In particular, it is shown that the force imparted to the platform is a combination of the impact of the sand on top of the explosion gas bubble and the pressure of the bubble as it expands before venting into the atmosphere. Under certain conditions, when the platform standoff is sufficiently small and the platform is sufficiently large, the bubble can over-expand before venting and pull the platform downward. This phenomenon was studied further through carefully measured and photographed small-scale experiments performed at the University of Maryland [2]. The small-scale experiments provide additional important validation benchmarks for our model.

Jan 1, 2005

By Jai Ghosh, Aprad E. Torma, Roger Guay

The catalytic effect of ferrous ion in the industrial biohydrometallurgical heap and dump leaching processes is explained. During the bacterial leaching of metal sulfides, ferric ion will partly be hydrolyzed and a variety of sols, gels, amorphous and/ or crystalline mono- and polynuc- lear hydroxo- and sulfato complex species formed, especially by olation and aggregation reactions. There are many problems associated with these iron precipitates especially in the purification of leach solutions. The present study will discuss the iron precipitation reactions; gives kinetic and thermodynamic evaluations of the effect of temperature on pyrite and ferrous iron oxidation; and reports on the tolerance of heavy metal ion concentrations by Thiobacillus ferrooxidans.

Jan 1, 1989

By Mark S. Stagg, David E. Siskind

The mining industry occasionally blasts near pressurized transmission pipelines and has requested guidance of safe vibration levels and setback distances. the Bureau of Mines and the Indiana Department of Natural Resources cooperated with AMAX Coal Company on a study of coal mine overburden blasting. Five buried and pressurized 250-ft pipeline sections were specifically installed on the Minnehaha Mine highwall near Sullivan, IN for testing to failure. Four welded steel pipes ranging from 6- to 20- in diameter and one 8- PVC water supply pipe were monitored for vibration, strain, and internal pressure for a period of 6 months while production blasting advanced up to the pipeline field. In contrast to previous studies of small-scale blasting representing construction activities, these tests involved overburden blasts of up to 2100 lb per delay in 12-l/4-in diameter holes.

Jan 1, 1996

By F. D. Ford, Z. Dai

"Vale’s Ontario Operations re-introduced Cu/Ni separation at Clarabelle Mill in 2006. The mill processes ores from a number of mines in the Sudbury basin. A saleable Cu concentrate is produced at 30-60% Cu recovery from mill feed, which has to meet the quality specification. In particular, Ni content in Cu concentrate must be less than 0.6%, otherwise, penalties will apply and diminish the value of Cu concentrate, in addition to the lost Ni value. Generally, a Ni grade of less than 0.4% is obtained in Cu concentrate. More recently, while processing Cu-rich ore, Cu concentrate contained more than 0.6% Ni which is abnormally high. Detailed mineralogical investigation shows that Cu-rich ore contains more millerite in comparison to typical Sudbury Ni sulphide ore. Millerite is found to be more floatable than pentlandite and is much more difficult to depress using high-lime aeration conditioning, which is the standard practice in Cu/Ni separation to float chalcopyrite while depressing pentlandite. The current operation uses sodium cyanide at 20 g/t to depress pentlandite and pyrrhotite. However, it is found that a high dosage is required to depress millerite. It is also shown that starch and dextrin are promising in millerite depression.INTRODUCTIONPrior to bulk smelting in 1991, Cu/Ni separation was carried out at Vale’s Copper Cliff Mill, Ontario Operation. The typical Cu concentrate grade was around 30% Cu and 1% Ni. This is very high in comparison to today’s value of 0.4% Ni and would not be acceptable for external processing. However, the Cu concentrate was processed internally at the Copper Cliff smelter/refinery, so the Ni contained in Cu concentrate was not lost and no actual penalties applied. During the SO2 abatement initiative, bulk smelting was chosen because of the perceived simplicity and consequently, Cu/Ni separation was eliminated (Agar, 1991) and the Copper Cliff mill was subsequently demolished. In 2005 and after more than one decade of bulk smelting, business changes required the removal of some Cu concentrate from Clarabelle Mill bulk concentrate to provide smelter capacity for Voisey’s Bay concentrate in the Copper Cliff smelter. In essence, this strategy calls for Cu removal at Clarabelle Mill (Lawson, 2006). In this case, Cu concentrate is sold externally and it must meet the quality requirement of less than 0.6% Ni."

Jan 1, 2011

By W. R. Reed, G. J. Joy

The personal dust monitor (PDM) is a new coal mine respirable dust sampling instrument that has the ability to provide accurate end-of-shift and real-time respirable dust exposure data. A hypothetical cost comparison analysis of the PDM with the current MSHA-required coal mine dust personal sampling unit (CMDPSU) was conducted. Some simplifying assumptions were made to create hypothetical cases for analysis. This analysis was limited to respirable dust sampling of one designated operator (DO) and one designated area (DA) for one mechanized mining unit (MMU) which operated one shift per day. Only sampling intervals of the minimum sampling as required by federal regulations and continuous sampling were analyzed. This cost analysis from the company perspective is only one part of an overall cost/benefit analysis that should be conducted at a later date. In this analysis, company-associated costs were examined for both sampling systems. Results show that the PDM, while it has high initial costs of approximately $12,600, may be a cost-effective sampling system for measuring coal mine respirable dust. The estimated present worth cost of conducting the minimum required dust sampling over a five-year life ranges from $5,850 to $19,000 for the CMDPSU, with the higher present worth cost including costs of potential violations incurred. For the PDM, the comparable present worth cost is $14,900 to $19,300, with the lower present worth cost representing a lower capital cost of $8,150 per unit if more than 850 units are produced per year, while the higher present worth cost reflects the result with the higher $12,600 capital cost.

FROM time to time articles have appeared in the technical press on the interesting subject of surface combustion. The theoretical part of the problem has, for practical purposes, received ample consideration in those articles, but the number of practical applications of surface combustion referred to has generally been very small.It is the writer's object to review some recent developments in surface combustion, and also to try to arrive at an estimate of its advantages and possibilities. It is not necessary for this purpose to dilate upon the phenomenon of surface combustion itself. Many interesting things have been said on the subject by Pro£. W. A. Bone, of Leeds, to whose researches the recent developments are largely due. A few illustrations may make clear what is meant by surface combustion.Prof. Bone, in an experiment, took a platinum crucible, which he heated in the flame of a Meker-burner. Then he turned the gas off for a second, and, opening the stop-cock again, allowed the combustible mixture to impinge upon the crucible, thetemperature of which was still well below the ignition temperature of the gas. Although no flame was visible at this stage, it was soon clear that, nevertheless, the gas and air had continued to combine, as the crucible would attain a red heat after a few seconds.Another instance of surface combustion was shown by a Mr. Fletcher, in 1882. He placed an iron ball, weighing 3 lb., on a slab of fireclay, heated it for a few seconds with a blow-pipe, and blew the flame out, leaving the gas-mixture still...

Jan 1, 1915

"The Detour Lake Mine is located in northeastern, Ontario, approximately 300 kilometres northest of Timmins and 185 kilometres by road northeast of Cochrane. The mill processes a free milling gold ore using both gravity circuit and leaching with a state-of-the-art carbon-in-pulp circuit. The grinding circuit is a conventional SABC circuit with a tonnage of 55,000 mtpd at 95 microns with the addition of pre-crushing upstream of the SAG mill.The present paper will describe the methodology used to successfully prove that gold of the Detour Lake Mine ore is mostly concentrated into the fine size fraction of the blasted rocks. It will describe the various options possible to create value from this ore property.IntroductionThe purpose of this test work was to determine the grade of the pebbles and consider if there was value into discarding the pebbles and replacing the material by fresh feed.1. Pebble samplingThe pebbles were sampled and assayed for grade every day for 3 months. After 3 months of sampling, the results showed that the pebbles only carried 28% of the fresh feed grade. This phenomenon can possibly be explained by the fact the gold is located into area of fracture in the rocks.January-March 2014 – Pebble assay average• Line #1 = 0.222 g. Au/t• Line#2 = 0.275 g. Au/t• Head grade = 0.88 g. Au/t2. Crushing and grinding circuit surveysWith the above information, a grinding circuit survey was planned. The purpose of the survey was to build a JKSIMMET model of the grinding circuit for mill optimization but also to understand the deportment of gold into various size fractions that may explain why there is so little gold in the pebbles. All streams and size fractions was analysed for particle size analysis and for gold.Since Detour has dual grinding lines, both circuits were sample at the end of May. Two supplemental survey of the secondary crushers were also done and a survey of the gyratory crusher."

Jan 1, 2016

By Manqiu Xu, Glen Robertson, Steve Wilson, Pete Quinn

"The middlings circuit, once called the pyrrhotite rejection circuit, at Inco’s Clarabelle mill was a single flotation stage. It used to process a combined feed consisting of the main flotation scavenger concentrate and the non-magnetic portion of the magnetics flotation circuit tails. The typical circuit metallurgy was 55% nickel recovery at 6.5% Cu+Ni concentrate grade. In the past few years, a research project with the objective of improving the circuit metallurgy was initiated between Inco’s research laboratory and the Mill’s Process Technology group. This project has gone through three steps: a) initial laboratory studies, b) on-site pilot plant investigation, and finally c) full plant implementation.The present paper describes the initial laboratory test work. The development of a two-stage circuit consisting of separate rock and pyrrhotite rejection stages to replace the simultaneous rejection of both rock and pyrrhotite in a single stage is discussed. A two-stage circuit simulation based on batch laboratory flotation data is also presented. Further development work, including the on-site pilot plant test work and the plant implementation of the new circuit design, will be described in a later publication.INTRODUCTIONThe milling operation at Inco’s Clarabelle mill, Copper Cliff, Ontario processes a rich complex sulfide ore from several large production mines around the Sudbury basin (Agar, 199 1). The sulfide mineralization is simple, consisting of chalcopyrite (Cp), pentlandite (Pn) and pyrrhotite (Po). The main gangue minerals are pyroxene, feldspar and quartz with minor amphibole and talc. Estimates of mineral composition are routinely calculated from Cu, Ni and S assays. In the mineralogical calculations, all gangue minerals are conveniently grouped and treated as rock (Rk)."

Jan 1, 2000

By John D. Spencer

Surveys to establish the quantity and quality of coals available for metallurgical, industrial, and energy use, investigations to develop better mining methods, and studies aimed at improving the health and safety of those who mine the coal highlighted Bureau of Mines research and technologic work on coal in 1968. Also being developed are more efficient methods of coal preparation, transportation, storage, and utilization. Supplementing this effort are projects designed to assure minimum disturbance of land, water, and air resources. Research centers and laboratories of the Bureau of Mines are listed in appendix A. Publications released during 1968 are cited with the various projects and in appendix C. Organizations that cooperated in the work in various ways are cited in appendix B.

Jan 1, 1969