Search Documents

Semisoluble salt minerals are characterized by their ionic bonding and are distinguished from soluble salt minerals by their limited solubility in water. One group of semisoluble salt minerals being considered is the alkaline earth salt minerals, including fluorite (CaF2), calcite (CaCO3) and apatite (Ca5F (PO4)3), as well as celestite (SrSO4) and barite (BaSO4). Another group of semisoluble salt minerals being considered is the rare-earth salts, which include bastnaesite ((Ce, La) CO3F), monazite (CePO4) and xenotime (YPO4). Surface chemistry features of these selected semisoluble salt minerals are discussed with respect to flotation separations. First, the surface chemistry features of alkaline earth semisoluble salt minerals are reviewed, and then the surface chemistry features of rare-earth semisoluble salt minerals are examined. The discussion includes electrokinetic behavior, wetting characteristics and collector adsorption.

By Anuradha Khetwal, Sandeep Khetwal, Andrea Panciera

The observation method is a design optimization approach for the drill and blast method in tunneling. This method includes first identifying the hazard scenarios through site investigation, formulating suitable solutions, obtaining feedback during construction, and finally using that data to optimize the design methods. This paper illustrates the application of the observational method for T-48, a railway tunnel project in the Himalayas. It is a 10.2 km long tunnel with a parallel escape tunnel and 26 cross passages. The use of observational methods in this project optimized the overall tunnel design and considerably saved the overall project cost.

Jun 23, 2024

By W. V. Liu, D. Omane, H. Yu, Y. Pourrahimian

"A large-scale wildfire had broken out at Fort McMurray in Alberta, Canada during May 2016. Many oil sands mining activities were affected due to the wildfire and the associated ash emissions. In particular, ash emission generated from the fire outbreak is a huge problem during the post-fire cleanup. These emissions pose a severe health hazard to workers, environment, and global climate. The ashes emitted into the atmosphere are caused by either human activities or climate conditions. The objective of this research is to assess the effect of three different ash dust suppressants, namely water, #1 surfactants, and #2 polymers at various volumetric concentrations on ashes samples to prevent propagation of fine solid emissions into the atmosphere. It is found that both #1 surfactants solution and #2 polymers solution are effective in retaining fugitive ash dust generated from the ashes. Volumetric concentration efficiency of 0.05% of #1 surfactant and 5% of #2 polymers in 500 ml of water have been proven to provide ash dust retention efficiency greater than 99% after the spraying of these suppressants. It is also found that both #1 surfactants solution and #2 polymers solution maintain an ash dust retention efficiency higher than that of the use of only water. This confirms the merit of using chemical dust suppressants on fugitive ash dust for a longer period, which is proven by the 72-hour data from this experiment. This study gives a general view of how effective chemical suppressants on fugitive ash emissions work. INTRODUCTION On May 1st, 2016, a large-scale wildfire gutted Fort McMurray, Alberta, Canada. Many oil sands mining activities were affected due to the wildfire and the associated ash emission. Due to the wildfire, some of the biggest oil sands companies in Fort McMurray such as Royal Dutch Shell and Suncor Energy shut down their oil production, at 255,000 and 350,000 barrels per day respectively [1]. Syncrude Canada Ltd scaled down its normal production capacity level of 350,000 barrels per day [1]. This generated an estimated loss of about 1.1 million barrels of oil production per day, constituting a 30% reduction in the Canadian daily oil production, crippling the economy [2]. This loss in production by the companies translated into 0.33 % of the Alberta GDP in 2016 constituting a loss of $985 million and 0.06 % of the entire Canadian economy [3]. In 2017, it is estimated that the rebuilding and reclamation of the affected areas in Fort McMurray will add $ 1.3 billion in GDP to Alberta’s economy [3]. A population of over 90,000 people was evacuated from the location and its surroundings for health and safety reasons [4]. The fire destroyed about 2,400 structures and over 500,000 hectares of forest vegetation in Fort McMurray, leaving an estimated 232,000 tonne of post-fire ashes [5,6]."

Jan 1, 2017

By Richard B. Berg

Chlorite veins in the Silver Star district (40 km southeast of Butte) were of little interest to those who were mining gold and silver in the late 19th century. It wasn't until 1975 that unusually pure magnesian chlorite of the variety clinochlore was identified from a ?talc? claim in this district. In 1977 tests by Cyprus Industrial Minerals showed that this chlorite was suitable for use in ceramics. Mining begun in that year continues. These replacement veins of chlorite in Precambrian quartzofeldspathic gneiss differ from the metalliferous veins to the northwest in both attitude and mineralogy.

Jan 1, 1982

In early 1970, General Mills Chemicals, Inc. announced the availability of en improved liquid ion exchange reagent, LIX® 64N, for the recovery of copper from various solutions, such as dump leach liquors. LIX 64N has been shown to be a considerable advance over LIX 64, and is presently in use in three commercial plants. Results have been very gratifying. For example, one of the plants was designed for operational production of 40,000 pounds copper per day, and in fact reached this output within the third week following startup of the plant. In addition to the operating plants, another is scheduled to come on stream this month with L D( 64N being used to extract and recover both copper and nickel. The chemical properties and operating characteristics of this reagent have been fully described in a previous paper. 1 LIX 64N is quite an effective and selective extractint for copper, even with copper contents as high as 15 g/l, but the reagent is somewhat limited in pH range, and loses some of its extraction efficiency as the pH drops below 0.8. Liquors derived from vat leaching, electrolytic tankhouae bleed streams, or some of the new leach schemes derived to solubilize copper from sulfide concentrates are examples of the liquors that present major problems when treated via liquid ion exchange. LIX 64N could extract some of the copper from such streams, but recovery was limited to about 75 percent. Also, in some parts of the world there are streams which are relatively low in copper (-5 g/l) but which are very high in acid (25-50 g/1 H2SO4). Again, LIX 64N can attain only about 75 percent recovery from such streams. For effective treatment, these streams require a reagent which will maintain the excellent selectivity of LIX 64N, and will

Jan 1, 1971

By J. O. Stephens

During the late 1940's and early 1950?s, the Westinghouse Combustion Turbine Division built and demonstrated a residual oil-burning locomotive on six eastern railroads. Plans were made to convert to burning pulverized coal, and a single combustor was operated at a full-pressure condition in the laboratory for about two years. During the mid-1960's to mid-1970's, there was considerable interest in coal-burning MHD and a combustor was developed which would also be applicable to combustion turbines. In the early 19801s, the BCR National Laboratory (BCRNL) became affiliated with the University of Pittsburgh, and a program was begun, supported by the Stare of Pennsylvania, to develop an all-purpose combustor for use with industrial and utility boilers and eventually with combustion turbines. In this paper, we review the work of almost 40 years, indicate our present position, and propose steps to be taken leading to efficient and environmentally acceptable power generation from coal, and specifically to coal-burning locomotives.

Jan 1, 1986

By D. McSwain-Santos

Soda ash is the trade name for sodium carbonate, a chemical refined from the mineral trona or naturally occurring sodium carbonate-bearing brines (both referred to as natural soda ash) or manufactured from one of several chemical processes (referred to as synthetic soda ash). It is an essential raw material in glass, chemicals, detergents and other important industrial products. Production U.S. soda ash production during 2004 increased to10.9 million Mt (12 million st). Five companies comprised the domestic soda ash industry. Four were in Wyoming operating five plants. One was in California with one plant.

Jan 1, 2005

By Leandro Augusto Viana Teixeira, Angela Avelar, Ruberlan Gomes Silva, Virginia S. T. Ciminelli, Daniel Majuste

Rare earth elements are essential for modern life products and green technologies. Recent supply constraints have boosted the development of rare earth projects after the price peak of 2011. The feasibility of a project depends on the definition of a processing route, which in turn depends primarily on the rare earth mineral, with monazite and bastnaesite representing the two most relevant minerals. Monazite-type ores usually contain high acid consumption impurities, such as iron, aluminum, calcium, magnesium, and phosphates, and may also contain prohibitive levels of radioactive thorium in its composition. This work presents a thermodynamic analysis of a monazite system and discusses the fundamentals of a selective process route for rare earth extraction from monazite ores with high iron content. This process involves sulfation by means of concentrated sulfuric acid and roasting at a high temperature. The route yields high rare earth extraction with low iron and thorium extractions and low acid consumption. Rare earth extractions as high as 80% were achieved, while iron and thorium extractions were lower than 1%, and acid consumption was lower than 0.34 kg of sulfuric acid per kg of ore. The operational window was compared to the one predicted by thermodynamic modeling, with 700 °C representing the optimal roasting temperature

By Shakuntala Tudu, Indrajit Paul, Surajit Sinha, Pulibandla Basaveswara Rao, Shaik Mahaboob Basha, Srinivas Dwarapudi

The iron and steel manufacturing sector directly accounts for 7–9% of global CO2 emissions. Raw material preparation, such as iron ore sintering, pelletizing, and cock making, is the major CO2 emitter. As climate change becomes a bigger concern, steel manufacturers need to lower CO2 emissions without hindering efficiency or increasing costs. In recent years, the percentage of iron ore pellets in blast furnaces has increased due to its uniform size, good reducibility, and high tumbler index. Pelletizing is energy-intensive and emits considerable CO2. Around 20% of CO2 emissions during pellet making come from fluxes. In the present work, the authors established a novel CO2- free flux called wollastonite (CaO.SiO2) for sustainable palletization. Pellets with varying percentages of wollastonite (0–6%) are prepared and tested for chemical, physical, and metallurgical properties. Image analysis through an optical microscope is carried out to quantify the phases of fired pellets. SEM–EDS is performed to evaluate the chemical composition of the melt and slag phases. The results showed that the reducibility index (RI) and swelling index (SI) of pellets decreased with an increase in wollastonite dosage. Pellet strength increases with an increase in wollastonite addition up to 1.2% CaO (2.27% wollastonite), and a decrease in strength is observed thereafter. The increase in strength is attributed to the increase in slag bonds. The decrease in strength beyond 1.2% CaO is mainly because of an increase in low melting eutectics and more magnetite content. Pellets with 2.27% wollastonite to get 1.2% CaO showed good physical and metallurgical properties.

Mar 4, 2024

By J. R. Goode

The first part of this paper comprises a general discussion on refractory gold ores and their mineralogy processing methods now in use are reviewed and test procedures for the important methods are discussed. Factors determining the selection of a process are outlined. The paper includes a survey of production plants using pressure oxidation, roasting and biological oxidation to process refractory ore. The status of processes under development is briefly reviewed.

Jan 1, 1993

By T. W. Camm

"We hear all the time about the value of hard work and perseverance, and the part they play in the professional life of successful people. What we do not hear so much about are the many professionals who work hard and persevere, yet never seem to quite reach the level of success they aim for. Some current authors are beginning to give more attention to the part luck/black swans/outliers play in success. This is not a new phenomenon, Machiavelli had a lot to say about it back in the Renaissance. So how can knowledge of this dynamic help in a modern organization? INTRODUCTION Work hard and you will succeed. Go to the right school, major in the right degree, study hard, and get a good job. Look at the lives of successful people, and do what they do. Be all that you can be. You can be anything you want to be. Really? Those who are successful always get attention, people want to know what they did to reach such a high position. Invariably, at least part of their narrative will include hard work, wise insight, taking advantage of opportunities, etc. If they are of a more generous nature, they might also allow that building the right friendships and collaborations also played a role. All of this may be true; what we do not often hear are the stories of those who did all of these very same things, but did not find success. An example from pop culture: The Voice. I have watched this show occasionally the past couple of years. One of the things I like about the show is that the initial screening of contestants is based solely on their singing voice (hence the name of the show), and not on their appearance. At the time of this writing (early November), the judges have just finished elimination rounds for their final teams to go on to the live shows. Here is my point—in almost every case the judges agonized over choosing who would go forward and who would be eliminated. And the reason is because all of them are really talented singers. It is impressive how gifted they are. At the end of each season, only one is declared a winner, out of that gifted pool of singers. When you hear their stories, they are all talented, hard-working individuals sacrificing for their art. And as far as I know, none of them has ever become a star. Hard work, dedication, sacrifice, talent—sometimes it is enough, sometimes not. I will be looking at the part uncertainty/luck/black swans play in our lives, but I want to make it clear at the beginning that I am not saying everything that happens to us is out of our hands or beyond our control. Taleb makes this same point (2007, p. 52): “This problem is chronic: if you tell people that the key to success is not always skills, they think that you are telling them that it is never skills, always luck.”"

Jan 1, 2017

By Gleason

"From June 16 to 19, more than 1,400 tunneling and underground construction professionals gathered in Chicago, IL for the bienial Rapid Excavation and Tunneling Conference (RETC). There, they were greeted by a full technical program and an exciting exhibit hall that provided a comprehensive look at the world’s bustling tunneling and underground construction industry.The successful conference was a reflection of the industry itself, which is to say, busy. As much of the world has begun to focus on creating a cleaner and greener environment, the global tunneling industry has seen an uptick in infrastructure projects move from design-build to construction phase. With a global shift away from the use of fossil fuels, major cities around the world are looking to increase public transportation options, which leads to the need for more transportation tunnels. And as urban populations continue to grow, the need for clean water calls for more tunnels, and as urban footprints continue to expand, the need to increase and update combined sewage overflow tunnel grows with them.During two and a half days, more than 20 sessions covering all of these topics were presented at the Hyatt Regency in Chicago, many to packed rooms in which every seat was taken and people were standing along the side and back walls.RETC is a biennial conference and one of the largest in the North America for the tunneling and underground construction industries. As such, it hosts a robust exhibit floor. This year 172 vendors occupied 205 booth spaces. The exhibit included everything from tunnel boring machine manufacturers, like Robbins and Herrenknecht, to the companies that supply all kinds of parts and services to the industry."

Sep 1, 2019

By Robert D. Saltsman

The inadequacy of our knowledge of the coal combustion process has long been recognized. This was expressed very well by Spicer and Finney (1). "The control of combustion processes in industry and the design of the equipment necessary for efficient burning to take place have always been very much branches of an industrial art rather than of an exact science. This has been especially true of the utilization of coal, a substance so hetrogeneous and complex in character that all too little is known about its chemical and physical composition.' During the past several years one branch of coal utilization, that of high temperature carbonization; has made significant advances from being an art into being an exact science. This has been accomplished by the development of petrographic techniques for identifying, measuring, and determining the thermal properties of the organic materials which affect the carbonization of coal and the correlation of this information with a pre-existing standard of coke quality, the stability index.

Jan 1, 1964

By T. G. Legare

It is now well documented that trace amounts of silver, gold, and platinum group metals occur in certain geothermal brine deposits. A significant body of literature has been generated over the last twenty years which describes attempts to quantify the frequency and levels of these precious metals in the brines. This literature is often confusing and contradictory. For example Barnea 1 states that the Salton Sea geothermal field carries 2 ppm gold, yet more recent data by workers at Lawrence Livermore National Laboratory2 (LLNL) concludes that the gold level in Salton Sea brine is <0.07 ppb. They report a platinum level in one well of 55 ppb. This apparent contradiction may be explained by sampling source and technique, but is most probably explained by difference in analytical technique. Analytical techniques and problems will be discussed in the next section.

Jan 1, 1985

By Neel Gupta, Dustin M. Crandall, Brijes Mishra

X-ray computed tomography (CT) images of rock specimens often contain artifacts which must be corrected before scientific analyses are performed. This paper presents a new workflow of automated image processing to utilize poor-quality X-ray CT scan images. The workflow runs on the open-source image analysis software and efficiently separates desired features from low-contrast scanned images. The new workflow is a two-step technique using contrast enhancement and automated feature segmentation to generate noise-free binary images. The results of binary images using the proposed workflow and using a conventional thresholding technique are analyzed to show the quality of the proposed method. The paper also presents a workflow of estimating the structural geometries of features in two and three dimensions. The results of the structural feature analyses and computational time were compared between the open-source (ImageJ) and commercial image analysis software (Bruker Computed Tomography Analyzer). The commercial software was more computationally efficient, but the task-specific macros in open-source software enabled the user-desired automation in image processing and data extraction of desired structural features of comparable quality.

Sep 8, 2022

By B. Stewart

Recent ore pass failures have underlined the need for improved designs, standards, structural monitoring methods, and better hang up prevention and removal techniques. Researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) are investigating methods to improve safety during transport of ore in ore passes. Design criteria and hang-up prevention and remediation strategies involve studies of the effects of static and dynamic ore and waste rock loads on chutes, walls, gates, and support structures. Particle flow analysis methods were used to simulate the response of various ore pass designs to a wide range of ore loading conditions. A full-scale mock-up of actual ore pass and chute assemblies was duplicated and tested for load response. Data from a particle flow code and the mock-ups were com-pared. Loads on an active ore pass chute were measured.

Jan 1, 1998

Within the research project "Mine Development" funded by the "Austrian Fonds zur Forderung der wissenschaftlichen Forschung (FWF) " (funds for scientific research) between 1991 and 1993 150 underground hardrock mines in Europe, Northern America, Australia and Japan have been visited to analyze their general design and layout. The main aim of the project was to develop strategies for accessing new underground hardrock mines and to establish a mine planning database. The investigation included mines in high developed countries only, with a comparable labor cost situation. This paper presents the results of one part of the project, which deals with investigations into the influence of different parameters on the design of the primary access for a mine.

Jan 1, 1995

By Thomas Novak, Sampurna Arya

Controlling dust generation and keeping it below permissible limits to meet federal dust standards at the working face of a roomand-pillar coal mine is a challenge for a mine operator. With the recent changes in federal dust regulations requiring lower worker exposure, maintaining compliance has become increasingly difficult. The current most effective practice of dust control at a continuous miner face in an underground mine is the use of a flooded-bed scrubber. A study carried out by the National Institute for Occupational Safety and Health (NIOSH) indicated that a flooded-bed scrubber could achieve cleaning efficiencies between 58 and 90%. But, the operation of such a system is maintenance intensive. The flooded-bed scrubber screen becomes clogged with dust particles and requires frequent cleaning to maintain performance. However, the dust control issue is not solely a mining industry problem. Other industries face similar issues. The University of Kentucky collaborated with Toyota Motor Manufacturing on the development of a novel wet scrubber, called the vortecone scrubber, for capturing oversprayed paint particles in automotive paint booths. The vortecone scrubber achieved a cleaning efficiency of 99% and required minimal maintenance. This study aims to assess the ability of this vortecone scrubber to capture respirable dust in an underground coal mine. The paper presents the results of computational fluid dynamics (CFD) modeling of this vortecone scrubber. It discusses the effects of air quantity and dust particle size on the performance of the scrubber.

By Wern-ping N. Chen

Pressure tunnel includes water-supply tunnels and tunnels for hydroelectrical power plants. Their design principles are different from those of water/wastewater/conveyance and transportation tunnels. Though theoretical pressure tunnel design guidelines exist, a comprehensive guide to summarize these guidelines to facilitate the planning and design of a pressure tunnel program is lacking. The purpose of this paper is to fulfill this need. It first provides key pressure tunnel design concepts in hard rock environment; then, it illustrates associated final lining design principles, including the design of un-reinforced concrete lining, steel lining, and reinforced concrete lining. Design diagrams and a flowchart for the reinforced concrete lining design are provided.

Dec 1, 2022

By G. Ferrara

The paper describes the new design criteria and control strategies for multi-density dense medium separation (DMS) circuits. The role of the multi-density separation is discussed, and it is emphasized that for many processing problems -related to minerals and coals -it may be very important to perform two or more cuts at different densities in order to obtain a remarkable improvement in quality of products, process efficiency and economy. The two-density separation by dense medium cyclones was generally performed using two dense medium plants in sequence. In contrast to the former technology, the multi-density separation can now be performed by using a single medium circuit composed of different interconnected medium sumps. The sumps, one for each density, are fed with different medium streams selected according to their density, size composition and content in non-magnetic contaminant in such a way that the rheological properties of the media are optimized. This new technology is based on dynamic systems to density the medium, on the size-density segregation of the medium in the cyclones and separating devices and on accurate control systems for the density, viscosity and stability of the dense media of the different sumps. The present paper reports on the theoretical basis for the new, advanced medium circuits and on the systems for the control of the densities and of the rheological properties of the dense media. A typical circuit for a two-density separation is also described, and some industrial applications reported and discussed.

Jan 1, 1994