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By B. H. Clemmons, B. G. Saunders, R. H. Stacy

"INTRODUCTION This investigation was undertaken to determine the response of Birmingham (Alabama) red-iron ore to heavy-medium concentration. Specifically, the work involved a study of the efficiency of the process in separating coarse gangue diluents from the ore and an endeavor to evaluate the potential economic results. The investigative work was not intended, nor is it to be construed, to be adequately exhaustive in scope to enable immediate plant construction. Rather, the primary objective was to determine the grade of ore that could be produced by heavy-medium treatment and the resulting indicative or tentative benefits to be derived from such treatment. The latter, in turn, would determine the merits of the more exhaustive study that would be required for an ultimate decision on the heavy-medium treatment of the ores.The problem of avoiding excessive contamination of red-iron ores by shale and/or ferruginous sandstone has been before the operators of the iron mining industry of the Birmingham, Alabama, district for many years. Within the last two decades, increased mechanization of mining methods has increased this contamination to a considerable degree. In fact, general utilization of scraper loading and other mechanical methods of mining, in conjunction with small increases in the natural insoluble content of the ores, in some cases has actually resulted in the production of ""acid"" or excessively insoluble ore, where ""basic"" or excessively lime ores were produced formerly.The contaminating materials are derived largely from roof spells and natural parting seams in the ore, a condition that to some extent has been aggravated by the irregularity of the ore beds. The latter have been subjected to both primary and secondary folding in many places. Considerable faulting has taken place, also. In many localities these conditions render virtually impossible complete avoidance of ore contamination from the over and underlying sandstones and shales. However, in a few localities, where the ore beds are less disturbed and shale partings are absent, mining can and is being accomplished with relatively little dilution."

May 1, 1948

By R. K. Franklin, S. T. Reese, J. J. Forbes

"INTRODUCTION It is a recognized fact that in the coal-mining industry coal dust must be allayed to promote the safety and health of underground workers. The Bureau of Mines has been cognizant of the hazards of coal dust for many years, and the necessity of controlling such dust was acknowledged when the Federal Mine Safety Code was formulated. Accumulations of coal dust increase the explosion hazard in a bituminous-coal mine and facilitate the propagation of an explosion. Some of the coal dust produced in mining is inhaled by the workers and contributes to respiratory infection. Impairment of vision and personal discomfort resulting from working in dense clouds of coal dust reflect unfavorably on the efficiency of workmen. Considerable coal dust, originating at the working face, is carried in the ventilating current and deposited elsewhere in the mine, thereby increasing the explosion hazard. It is apparent, therefore, that if coal dust could be allayed effectively at its points of origin, the dust-explosion hazard in bituminous-coal mines would be reduced greatly.Although dust control is practiced in many bituminous-coal and lignite mines, the extent and effectiveness of control for the, entire industry-is not generally known. The purpose of this circular is to present such information clearly, and to encourage coal-mine operators to install dust- allaying equipment.Factual data on dust-allaying practices at working faces in a large number of the bituminous-coal and lignite mines in the United States were .compiled from reports on recent Federal inspections of these mines, The information is presented in tabular form to permit review of the dust-allaying practices of a substantial part of the industry, by States, and also according to employment, and loading practice."

May 1, 1950

By N. M. Skarbøvig

Safety nets have been used selectively in several South African mines over the years. Recently, however, an increased emphasis on mine safety has seen a resurgence of their utilization underground. This renewed interest has, however, also raised questions about the design and performance of these nets and their practical applications underground; these are the subjects of this paper. Generally, mine safety nets are used to protect personnel from falling rock in temporarily supported development ends, tunnels, ASGs and stopes. These diverse applications each require specific net designs, resulting in a wide product range. As a rule, however, mine safety nets need to carry specified static or dynamic loads with the least possible deformation. Because of the application-specific characteristics of mine safety nets, there is no South African national standard for them. Consequently, neither the SABS, nor the CSIR, performs standard tests on these components. In 2007, therefore, SIMRAC made available their Savuka facility for the testing of mine safety nets; the Savuka drop test became the accepted industry test standard for mine safety nets. From late 2007 to mid 2009, Norsenet, in collaboration with SRK Consulting, the designated operators of the site, conducted approximately 200 tests, which formed the core of Norsenet's database of safety net performance under various loading conditions. The test specimens comprised a wide range of net materials and config¬urations; the materials included: high density polyethylene, polypropylene, polyester, nylon, as well as a blend of polyester and polypropylene used primarily for reinforcement ropes. Net configurations encompassed the following parameters: net type, i.e., knotted nets or sewn nets; net strand type, i.e., braids, twines, or webbing; strand size; mesh size; mesh orientation, i.e., parallel or oblique to the net edge; net edge reinforcement, i.e., knotted, tied, with or without reinforcement ropes; internal reinforcement ropes, i.e., diagonal ropes and/or orthogonal ropes; as well as net attachment options, including loops and chainlinks. From the number of variables listed above, and the limited number of tests available, it can be appreciated that the findings of the test series required careful scrutiny. Nevertheless, principal performance factors clearly emerged: besides the obvious net mesh variables, such as net strand material, strand diameter and mesh size, it was the configuration of the reinforcement ropes and their attachment to the net panel which had the strongest influence on net performance. All the structural elements of a safety net need to work together to transfer the imposed load from the net panel, through the reinforcement ropes, to the net attachment points. In this load transference chain, the weakest link limits the strength of the structure. From this development work, Norsenet has gained valuable expertise to custom-design and manufacture nets to clients' specifications. The examples presented in the paper will also show the experience acquired in the installation of nets underground. Future work will include the establishment of a state-of-the-art net testing facility at Norsenet's factory in Vredenburg.. Keywords Mine safety net, safety net, protective device, mine safety, safety net design, safety net performance, safety net applications.

Jan 1, 2011

By Yuexin Han, Jie Liu, Shuai Yuan, Yanjun Li

"In order to improve recovery efficiency of iron minerals from iron ore tailings and to reduce its connected environmental pollution, this article investigated the reducing roasting of iron ore tailing in a laboratory fluidized magnetization roasting reactor to optimize the roasting method and conditions. The examined parameters included roasting temperature, roasting time and reducing atmosphere. The parameters evaluating magnetizing roast efficiency and theoretical value were determined. X-ray diffraction (XRD) analysis was used to investigate the conversion of iron phase after roasting. The results show that the best magnetizing roast conditions are roasting temperature of 540?, holding time of 15min, and CO concentration of 20%. The magnetization conversion ratio of roasting products is over 80%, under the best magnetic separation condition, the concentrate grade of iron is 65.61 % and the recovery of iron is 83.77 %. The XRD analysis shows that Fe exists in hematite and siderite before roasting and exists in magnetite after roasting. The technique not only recovers the iron minerals from tailings with good economic benefit, but also reduces the environmental pollution of tailings accumulation.INTRODUCTION Iron ore tailings are the solid wastes generated during the beneficiation process of iron ore concentration and are one of the main pollution concerns in the mining industry (Das et al., 1996). Continuous development of the iron and steel industry has led to the increasing amount of iron ore tailings; there are over 300 million tons of iron ore tailings discharged per year (Rao et al., 2016). The huge amount of stockpiled iron ore tailings brings a series of environmental and social problems. Comprehensive utilization of iron ore tailings can not only reduce environmental load but also conserve resources, promoting sustainable development of the society. In recent years, iron ore tailings as secondary resources have received considerable attention in many countries in the word and numbers of studies on utilization of iron ore tailings were carried out, such as recycling the valuable minerals (Datta et al., 1996; Jia et al., 2013; Panda et al., 2018), used in construction material compositions as alternative source of raw materials (Das et al., 2012; Zhou et al., 2012; Luo et al., 2016) and other utilization. The iron minerals were recovery by magnetization roasting (Rao et al., 2016; Yang et al., 2013; Yang et al., 2011) and flotation (Kumar and Mandre, 2016). By comparison the reduction roasting has more advantages, but it was found that the conventional roasting equipment was inefficient, high energy consumption and un-economically applied on an industrial-scale."

Jan 1, 2018

By H. R. Page, A. E. Jr Lee

A. E. LEE, JR. (author)—In addition to the paper we should like to make a few remarks. First, the seriousness of bending of the clay retort cannot be overemphasized. Not only did bending limit the length of the vessel, but it permitted corrosive fluid slags to concentrate in the belly of the retort and thus increased the possibility of boring. Bending also practically prohibited the use of cleanout machines and increased the danger of excessive fume losses by allowing furnace gases to escape around the top of the retort mouth. It will be noted that the Blackwell pottery practice places considerable emphasis on careful drying of retorts. Perhaps it is another smelter superstition, but traditionally the aging of retorts beyond a reasonable drying period has been considered important to long life. We are unable to give a good explanation of why aging should improve retorts. During the past fall in an attempt to prove a theory that the combined water in the clay decreased during aging, about 50 samples of wet retort collars were placed in a dry room when it was closed. Loss of weight, combined water and free moisture were measured each week over the 100 day drying period. The affinity of the dried retort for moisture makes difficult the accurate measurement of free water; however, there was a clearly defined free moisture change from about 12.5 pct when freshly made to about 2 pet at the end of 18 days, then a gradual loss to about 0.25 pet at 70 days and an apparent equilibrium near this figure through the 100th day. There was no appreciable change in the combined water. The change in weight of the average sample was, however, rather unusual, there being consistently a loss of weight throughout the entire 100 days. From the 63rd day on this leveled off to about 0.03 pet per week. These were small samples and certainly should have dried

Jan 1, 1950

By R. E. Hamilton

It is more than ten years since the first fully automated process using a computer started operation. Computer control has become common in a number of process industries, yet in spite of the tremendous incentives which ere present, there are only a few computer installations in the mining industry and none of these has announced successful control of a process. Recognizing that one of the reasons for this slow progress is the lack of adequate mathematical models of the various processes involved, the author's company started a project in the summer of 1966 to develop such models. It was early recognized that the existence of a major disturbance input, in the form of the mineral composition of the feed prevents most flotation plants from attaining a steady state condition. This makes the custom¬ary method of developing correlations from steady state plant data inapplicable and requires a more fundamental approach.

Jan 1, 1968

By Amy Nelson

In the electrolytic production of zinc, cobalt is removed from the zinc electrolyte by cementation with zinc dust prior to electrowinning. Although the thermodynamics for this reaction are favourable, kinetic barriers to cobalt reduction render the method almost useless in practice unless activators such as copper and antimony or arsenic are added. There is a large body of work studying the effect of these additives, yet the mechanism by which they act is still poorly understood. Even when the target conditions are met, zinc dust consumption is excessively high: satisfactory operation requires up to 300 times the stoichiometric amount of zinc dust. The objective of this work is three-fold: (1) to examine the effects of activators and elucidate the characteristics that make a good activator; (2) to identify new additives that could lead to a more efficient purification process; and (3) to test the new additives with synthetic and real electrolyte solutions. The present paper gives a status report on this project.

Jan 1, 1998

By James R. Kerr

This study reviews the sulfur and suliuric acid industries in Eastern United States with emphasis on patterns of consumption and marketing. Output of sulfur in the East is relatively small, and most of the area's sulfur requirements are met by gulf coast Frasch sulfur. Over the long ten recovered elemental sulfur from sour natural gas and petroleum may become the East's major source of sulfur. In 1958 sulfuric acid manufacture consumed over 80 percent of the area's sulfur requirements. The leading uses for sulfuric acid were the manufacture of superphosphates and chemicals. Over the years, unit requirements for sulfur and acid in many major markets have been reduced through improved technology, but new markets always have been developed to keep the industry vital and growing.

Jan 1, 1965

By J. R. Thoenen, M. C. Malamphy, G. K. Dale

The beginning of the war and the events leading up to it precipitated a near crisis in the aluminum industry. Demands for the metal reached proportions far beyond the prewar production capacities and, in addition, the submarine menace seriously curtailed the importation of bauxite from South America, hitherto a chief source of high-grade ore. The situation required an intensive search for domestic ore to augment the reserves and in October 1941 Congress directed the Department of the Interior to investigate the extent, mode of occurrence, and quality of bauxite in the United States. In December of that year the Bureau of Mines and the Geological Survey began the search for bauxite in Arkansas, where more than go per cent of the domestic ore had been produced and where the greatest amount of bauxite was known to occur. The program involves the geophysical and geological investigation of the Arkansas bauxite region and the core drilling of areas considered favorable for the occurrence of bauxite deposits. Cores taken from the bauxite-kaolin zone are sampled and analyzed in the Bureau of Mines laboratory in Little Rock. The information from each of the deposits discovered is then assembled, the bauxite is graded with respect to its possible utility, tonnage estimates are made, and the whole is presented in the form of a war minerals report. Thirty-eight new bauxite deposits had been discovered and investigated at the end of the calendar year 1944, and the presence of several others had been indicated by the drilling. More than 5000 holes had been drilled throughout the bauxite region, and more than 60,000 chemical analyses had been made of samples taken from the bauxite-kaolin zone. A study of the chemical analyses led to certain general conclusions not only with regard to the chemical composition of Arkansas bauxite, but also with regard to its component minerals. Charts and diagrams based on these conclusions have been developed for practical use by the Bureau of Mines: (I) to serve as a check against laboratory analyses, (2) to present tonnage estimates of ore bodies based on mineral composition, (3) to illustrate the relationship of tonnages of bauxite to the alumina, silica, and iron content, and (4) to serve as a control for mining operations by providing a means for quick estimates of the value of the ore from a partial analysis of its chemical constituents. The use of charts and diagrams similar to those discussed in this paper-- is not new. The use of the trilinear diagram for studying the ultimate analyses of coals as of proposed by Ralston in Bureau of Mines Technical Paper 93 (1915) showed that the various ranks of coal fell in different areas on the diagram and that volatile matter, calorific value and other properties could also be plotted by the use of contours. A considerable subsequent literature, largely on classification of coals, has accurnulated since then, showing the utility

Jan 1, 1948

By J. R. Thoenen, M. C. Malamphy, G. K. Dale

The beginning of the war and the events leading up to it precipitated a near crisis in the aluminum industry. Demands for the metal reached proportions far beyond the prewar production capacities and, in addition, the submarine menace seriously curtailed the importation of bauxite from South America, hitherto a chief source of high-grade ore. The situation required an intensive search for domestic ore to augment the reserves and in October 1941 Congress directed the Department of the Interior to investigate the extent, mode of occurrence, and quality of bauxite in the United States. In December of that year the Bureau of Mines and the Geological Survey began the search for bauxite in Arkansas, where more than go per cent of the domestic ore had been produced and where the greatest amount of bauxite was known to occur. The program involves the geophysical and geological investigation of the Arkansas bauxite region and the core drilling of areas considered favorable for the occurrence of bauxite deposits. Cores taken from the bauxite-kaolin zone are sampled and analyzed in the Bureau of Mines laboratory in Little Rock. The information from each of the deposits discovered is then assembled, the bauxite is graded with respect to its possible utility, tonnage estimates are made, and the whole is presented in the form of a war minerals report. Thirty-eight new bauxite deposits had been discovered and investigated at the end of the calendar year 1944, and the presence of several others had been indicated by the drilling. More than 5000 holes had been drilled throughout the bauxite region, and more than 60,000 chemical analyses had been made of samples taken from the bauxite-kaolin zone. A study of the chemical analyses led to certain general conclusions not only with regard to the chemical composition of Arkansas bauxite, but also with regard to its component minerals. Charts and diagrams based on these conclusions have been developed for practical use by the Bureau of Mines: (I) to serve as a check against laboratory analyses, (2) to present tonnage estimates of ore bodies based on mineral composition, (3) to illustrate the relationship of tonnages of bauxite to the alumina, silica, and iron content, and (4) to serve as a control for mining operations by providing a means for quick estimates of the value of the ore from a partial analysis of its chemical constituents. The use of charts and diagrams similar to those discussed in this paper-- is not new. The use of the trilinear diagram for studying the ultimate analyses of coals as of proposed by Ralston in Bureau of Mines Technical Paper 93 (1915) showed that the various ranks of coal fell in different areas on the diagram and that volatile matter, calorific value and other properties could also be plotted by the use of contours. A considerable subsequent literature, largely on classification of coals, has accurnulated since then, showing the utility

Jan 1, 1948

By Yong Pan, Srivatsan Jayaraman Sridharan, Purushotham Tukkaraja

Block cave mining method poses unique ventilation challenges compared to other underground metal mining methods. This research study focuses on assessing the airflow behavior in regulated airflow distribution systems by developing a 1:100 scaled block cave experimental model and a numerical model. This study also investigated gas flow behavior under various airflow conditions. Based on our findings, we observed that reduction in particle size and porosity of caved materials, decrease in cave footprint, and closure of undercut drifts would increase cave airflow resistance. The increased airflow is found beneficial for gas dilution regardless of its source locations, while the regulated airflow distribution system might deteriorate gas dilution situation when the source is located in the extraction drifts.

May 12, 2022

By M Balamurali

In mining, grade control generally focuses on blasthole sampling and the estimation of ore control block models with little or no attention given to how the materials are being excavated from the ground. In the process of loading trucks, the underlying variability of the individual bucket load will determine the variability of truck payload. Hence, accurate material movement demands a good knowledge of the excavation process and the buckets’ interaction with the environment. However, equipment frequently goes into off-nominal states due to unexpected delays, disturbances or faults. The large amount of such disturbances causes information loss that reduces the statistical power and biases estimates, leading to increased uncertainty in the production. A reliable method that inferences the missing knowledge about the interaction between the machine and the environment from the available data sources, is vital to accurately model the material movement. In this study, a twostep method was implemented that performed unsupervised clustering and then predicted the missing information. The first method is Density-based spatial clustering of applications with noise (DBSCAN) based spatial clustering which divides the diggers’ and buckets’ positional data into connected loading segments. Clear patterns of segmented bucket dig positions were observed. The second model utilised Gaussian process regression which was trained with the clustered data and the model was then used to infer the mean locations of the test clusters. Bucket dig locations were then simulated at the inferred mean locations for different durations and compared against the known bucket dig locations. This method was tested at an open pit mine in the Pilbara region of Western Australia. The experimental results demonstrate the advantage of the proposed method in inferencing the missing information of bucket-environment interactions and therefore enables miners to continuously track the material movement.

Jun 22, 2022

By Alexander V. Epiforov, Stanislav V. Balikov

This paper describes of processing tests of 8 flotation concentrates containing precious and base metals by pressure oxidation (POX) method. Concentrates 1 and 2 were gold-copper concentrates. Zinc and silver were by-products in these concentrates. These concentrates were processed by POX with following cyanidation of POX solid residues, copper solvent extraction and zinc carbonate precipitation. The recoveries of gold, copper, silver and zinc from these concentrate were 98, 99, 30 and 99%, respectively. Concentrates 3 and 4 were lead-zinc concentrates. Silver was by-product in concentrate 3. Gold, silver and copper were by-products in concentrate 4. Concentrate 3 was processed by POX with following reduction smelting of POX cakes for primary lead recovery and zinc carbonate precipitation from POX solution. The recoveries of lead and silver into ingot were 96 and 98%, respectively. The recovery of zinc was 99%. Concentrate 4 was processed by POX with following zinc carbonate precipitation and reduction smelting of POX cakes. Copper was precipitated from the POX solution using sodium sulphide prior zinc precipitation. The recovery of zinc into carbonate concentrate was 99%. The recoveries of lead, gold and silver into lead bullion were 95, 99 and 98% respectively. The recovery of copper into sulphide concentrate was 99%. Concentrate 5 was gold-pyrite concentrate, and concentrates 6-8 were double refractory gold-arsenopyrite concentrates. Silver was by-product in these concentrates. These concentrates processed by POX and CIL. The recovery of gold from concentrate 5 was 98%, and from concentrates 6-8 was 85-90. Low gold recovery from concentrates 6-8 was associated with preg-robbing factor. The recovery of silver from gold-sulphide concentrates did not exceed 10-20%. The low silver recovery was associated with argentojarosite formation that is resistant to cyanidation. The flowsheets for complex processing of precious and base metals sulphide flotation concentrates based on this test work results were proposed.

Jan 1, 2018

By A. F. Bridge

IN order to show the need for gas reserves, their control, and conservation, in California, it is necessary to describe briefly the local conditions under which gas is produced and marketed, to point out the lack of coordination between supply and demand, and to relate the history of efforts to prevent wastage. There are now 24 fields in California producing a surplus of gas over field fuel requirements. They are usually grouped geographically into three divisions, as follows: (I) Los Angeles Basin (Los Angeles and 0 r a n g e Counties), thirteen fields, all casing-head gas. Total daily gas available for sale 125,000, 000 ?cu.ft. (2) Coastal (Ventura and Santa Barbara Counties). Seven casine-head and one dry gas field. total-avail- able daily, 165,000,000 cu.ft. (3) San Joaquin Valley (Kern, Kings, Fresno, and San Joaquin Counties). Four casing-head fields, five dry gas fields, and two producing casing- head and dry gas from different zones. Total available daily pro- ducticon, 475,000,000 cu.ft. Total all fields, 765,000,000 cu.ft. daily.

Jan 1, 1936

By N. Duda, W. Koperska, S. Anufriiev, P. Stefaniak

In mineral processing plants ore extracted from mines is processed to obtain a concentrate with the highest possible concentration of this valuable product. It is a complicated multi-stage process. Usually, the first step is sieving the ore, which is typically done using vibrating mining screens. There is often only a limited number of these machines in the technological chain, which is why their continuous operation, and proper maintenance is crucial for the whole process. Predictive maintenance is the best strategy in this case because it allows for minimising the number and duration of unexpected stoppages. It consists of the prediction of future failures based on available real-time data, and predictive models built upon this data using, for example, machine learning techniques. In this paper we concentrate on feature generation for future predictive maintenance model development for a vibrating screen, based on an example of a KGHM ore processing facility in Polkowice-Sieroszowice. We focus on two types of measurements: bearings temperature and vibrational data. Based on the raw data, the process of more advanced feature engineering is described. By transforming the temperature data we calculate characteristics of bearing cooling and heating dynamics, while based on vibrational data, the aggregated characteristics of the vibrations are derived. Such features are calculated on a long-term basis, and then they are compared to the data related to vibrating screen maintenance to estimate their significance for the prediction of particular failures of the machine.

Sep 1, 2021

By Robert Keeney

THE electric smelting of manganese ore and the production of ferro- manganese did not exist as an industry, in the United States or elsewhere, previous to the outbreak of war in 1914. Ferromanganese had been produced, electrically, during times of high prices by two companies at Niagara Falls and by several European companies, but the production. was spasmodic, and none was electrically produced when ferromanganese sold at from $35 to $40 per ton. Thus the electric smelting of manganese ore must be considered as a development caused by the high prices prevailing during the years 1916, 1917 and 1918, and the necessity of smelting domestic ore in order to fill the ferromanganese requirements of the steel industry of the United States, which increased from 189,088 tons in 1914 to 356,356 tons in 1918. The electric furnace is well adapted to smelting domestic-ore because it can be located in small units near the source of ore supply. In 1918, the ferromanganese production of the United States was 333,027 tons, of which about 7 per cent., or 23,000 tons, was produced in the electric furnace. The electric furnace not only assisted materially in the development of a domestic-ore supply but made a considerable saving of coke, as it requires about 1,4 tons of bituminous or lignite coal per ton of ferromanganese compared with a blast-furnace consumption of 2.9 tons of coke per ton of ferromanganese. Some of the plants in the United States that smelted manganese ore in the electric furnace during the war and in 1920 are listed in Tabled. From early in 1919 to about February, 1920, little ferromanganese was produced in the electric furnace. During this period the price of ferro-manganese (78 to 82 per cent. manganese) was about $100 per ton. During the first half of 1920, several plants resumed operation when the, price of. ferromanganese (76 to 80 per cent. grade) gradually increased to $200 per ton, delivered.

Jan 2, 1921

By Daoxin Wu

Originated from(C4H9O)4Ti, nano--rutile TiO2 was synthesized by low temperature hydrolysis process in this paper. After being prepared by decomposing ammonium tungstate and covering on the surface of TiO2, TiO2/WO3 were characterized by means of X-ray diffraction(XRD), UV--vis difuse reflectance(DRS), fluorescence spectrum (FS). Results showed that with the increase of the supported concentration of WO3, the reflectance of DRS and the fluorescence spectrum intensity of TiO2/WO3 decreased accordingly, which indicated the powder?s increase in light absorbance and the decrease in luminescence respectively; with the increase of calcined temperature, the reflectance of DRS increased.

Jan 1, 2009

By Feridon Ghadimi, Saeed Mojeddifar, Massume Khavari

Separation of geochemical anomalies from background is an important and essential issue in the exploration of mineral deposits. Statistical methods are used to separation of anomaly from background. Fractal/multifractal and singularity methods are very suitable for the separation of weak anomalies. For interpolation, various methods could be used such as most distance-weighting methods, kriging, spline interpolation, interpolating polynomials, and finite difference methods. This paper addressed application of multifractal techniques together with finite difference procedure to detect the anomalous regions. Fractal models such as concentration–area, spectrum–area, and singularity index model were selected to identify Pb–Zn anomalies. In this research, 170 samples from 33 boreholes were taken in the Haft-Savaran area and analyzed for determination of Pb–Zn anomaly. Singularity method was a suitable method for separating Pb and Zn anomalies. Also, the results showed that the geochemical anomaly has occurred along NE–SW trend and is consistent with the sulfide mineralization process and the faults of the region.

May 18, 2020

By L. Yan, N. Damiano, J. Bickson, E. Bauer, D. Yantek, B. Whisner, M. Reyes, J. Srednicki

Built-in-place (BIP) refuge alternatives (RAs) are designed to provide a secure space for miners who cannot escape during a mine emergency. Heat and humidity buildup within RAs may expose miners to physiological hazards such as heat stress. To minimize the risk of heat stress, Title 30 Code of Federal Regulations (CFR), or 30 CFR, mandates a maximum allowable apparent temperature (AT) for an occupied RA of 35°C (95°F) [1]. The National Institute for Occupational Safety and Health (NIOSH) has conducted extensive research on the thermal environment of occupied RAs intended for use in underground coal mines. NIOSH research has demonstrated that a fully occupied BIP RA can exceed the AT limit by >5.6°C (10°F) in mines with elevated mine strata and air temperatures. In this circumstance, an RA cooling system could provide a solution. This paper provides an overview of test methodology and findings as well as guidance on improving the performance of a cryogenic air system prototype by optimizing the flow rate, increasing the tank storage capacity, and improving the efficiency of the heat exchanger of the cryogenic system. This may enable BIP RAs to meet the 35°C (95°F) AT limit in mines with elevated temperatures. The information in this paper is useful for RA manufacturers and mines that may choose to implement a cryogenic air system as a heat mitigation strategy. INTRODUCTION The apparent temperature inside an occupied RA could be significantly affected by the surrounding environment’s thermal conditions, such as mine air temperature and mine strata temperature. Apparent temperature (AT) is a temperature-humidity metric for the perceived temperature caused by the combined effects of air temperature, relative humidity (RH), and air velocity. It is used to assess the perception of indoor temperatures. Depending on factors such as geographic location and season, mine air temperature, relative humidity, and mine strata, temperatures can vary significantly [2]. RAs located in cold mines may pass the 96-hour 35°C (95°F) AT limit test that poses a challenge for RAs located in hot mines. One solution in these cases is that the occupancy of the RA could be derated (i.e., the RA occupancy could be reduced) to ensure the AT limit is not reached. However, this would require mines to purchase additional RAs to accommodate all personnel in the mine. For mines with high temperatures (above 26.7°C or 80°F), the occupancy might have to be reduced so much that the necessary number of additional RAs would be impractical. In these cases, RA cooling systems could provide a solution.

Jan 1, 2019

By Wilbur I. Duvall

A linear array of shot and gage holes 30 feet deep in a granite outcrop was used to compare the size and shape of radial strain pulses produced in the rock when short cylindrical charges of cast composition B were detonated axially or at one end. The axially detonated charges produced radial strain pulses that had shorter rise times and larger peak strain than the strain pulses produced by end detonated charges.

Jan 1, 1965