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By Paul J. Henkels

Synthetic gypsum is the calcium sulfate co-product of a number of industrial processes. Synthetic gypsum utilization as an alternative to the naturally occurring mineral continues to grow in the gypsum industry. In particular, flue gas desulfurization (FGD) gypsum produced by the electrical utility industry has had a significant impact and a far-reaching effect on the gypsum wallboard manufacturing industry. This paper will discuss the various synthetic gypsum sources verses natural gypsum and highlight issues of use in gypsum wallboard and related products.

Jan 1, 1999

In 1988, at the request of members of the Society for Mining, Metallurgy, and Exploration (SME) Inc., the president of SME formed Working Party No. 79, Ore Reserve Definition. Its mission was to develop guidelines for the public reporting of exploration information, resources and reserves. These guidelines were published in the April 1991 issue of Mining Engineering,(pp. 379-384), and as a document entitled "A Guide for Reporting Exploration Information, continued on an ad-hoc basis until 1996. Working Party No. 79 was then renamed the SME Committee on Re¬sources and Reserves and became a standing committee. Since 1994, the Council of Mining and Metallurgical

Jan 1, 1999

By B. A. Rose

Coal is being thermally dried in ever increasing tonnages today. Because of fire and explosion hazards, it is important that drying equipment be designed for maximum safety in operation. It is well then that we review dryer design and operation to bring out those features and operating practices which will provide maximum safety to equipment and personnel. This paper presents the author's views regarding the fundamental requirements for safety and explains the Heyl and Patterson approach to the meeting of those requirements in the design and operation of their dryer.

Jan 1, 1962

By J. W. Shuster

Test of trolley-diesel prime power is another step in the search to exploit the unused potential of electric wheel driven haulage trucks. The output of the present engine - a 700 horsepower diesel - is not adequate to exploit fully the 1200 horsepower potential of the two electric wheel drive motors. Power was supplied to a modified 100-ton haulage truck through a double wire trolley system. The vehicle was tested with various payloads on a 7% adverse grade haul road. More significant conclusions developed are: Power - Horsepower to propel the vehicle can he more than doubled to improve truck cycle time. Productivity - Trolley power up adverse grades can improve [producivity] rates from 18 to 36%, dependent upon haul road profile.

Jan 1, 1968

By Peter T. Luckie, Joseph W. III Leonard

INTRODUCTION In a bed of fine coal, water can be found in the interstices created by the particle surfaces and in the pores within the coal particles. The extent of the interstices voidage is obviously a function of the particle sizes and morphologies, as shown by the fact that the bulk density of coarse coal is greater than that of fine coal. After drainage, the voids can be completely or partially filled. By increasing the suction pressure across the bed, as is done in vacuum filtering, the quantity of water in the voids can be reduced. But eventually the increased suction pressure has little influence on the moisture reduction. In addition, the moisture in the pore structure of the coal is unaffected by the mechanical removal of the moisture in the interstices. When this condition is reached, the total moisture content of the coal can only be reduced further by evaporating the water. Evaporative drying is done for one or more of the following reasons: 1. To avoid freezing difficulties and to facilitate handling during shipment, storage, and transfer to the points of utilization. 2. To reduce the heat loss due to evaporation of the moisture from the coal during the combustion process, thus increasing heating efficiency. 3. To decrease transportation costs. The heating value of coal is equally improved for each percentage point reduction in the noncombustibles in coal. It is estimated that a reduction of 1%22 in the total moisture in the coal increases the thermal efficiency of the heat-raising process by about 0. Some coal buyers consider 1 % moisture content to be the equivalent of a 4% ash content.23 It is important to avoid drying the coal to too low a moisture level, since the complete removal of surface moisture to produce a bone dry product can result in a serious dust, wind lost, and safety problem. Surface moisture con- tents of 3% or less for shipped coal are not uncommon. However, the evaporatively dried coal may be lower, Y, to 1%, since the mechanically dewatered coal may be higher. Evaporatively dried coal can be treated (sprayed) with chemicals in order to control the dustiness and any freezing difficulties, thereby providing the producer with more operational flexibility. The evaporative drying of coal is essentially a process of simultaneous transfer of energy, usually in the form of heat, and water, in the form of vapor, from the coal. In order to remove the undesired moisture, it is necessary to raise the temperature of the water from the entering temperature of the feed stream, TF, to the boiling point of the water (usually taken as 212"F), vaporize

Jan 1, 1991

By Rasik H. Raythatha

Calcium carbonate is perhaps the most widely used mineral in the world. With total consumption of all calcium carbonate exceeding over 25 million tom per year, within this class of filler, a relatively smaller segment of precipitated calcium carbonates (PCC) is often misunderstood as a commodity product and bundled in the same category as ground calcium carbonate. However, each material has a distinctly digerent role and characteristics. Precipitated calcium carbonates are used to influence specific performance in a specific application whereas ground calcium carbonate is used primarily to reduce cost in many applications. In this paper, attempts are made to demonstrate the role of nano-fine-PCC in improving shear-thinning characteristics of common and specialized sealants and automotive underbody coating and how such "nano-particle" cal- cium carbonate properties can be exploited to process PVC plastics while reducing overall cost. We also review the role of precipitated calcium carbonate as "nano" material and why it must be viewed as a specialty additive.

Jan 1, 2003

PT Freeport's Mine in Irian Jaya, Indonesia uses a number of 500m long vertical ore passes to transfer ore from the open pit to the mill. The current tonnages moved are in the order of 125 ktpd and this will be increasing to 240 ktpd. This amount of falling rock generates high pressures in the ore bins, when ore feed is terminated the pressure is no longer constrained resulting in back blasting of materials and air up the ore passes. Three methods were tested to try and eliminate or reduce this problem; recirculation of the entrained air, widening of the orepasses and relieving the pressure of the back blast. The final method proved to be the most effective in the short term. As a long term solution the orepasses are currently undergoing widening.

Jan 1, 1998

By C. L. Karr

Establishing suitable control of pH, a requirement in a number of mineral and chemical industries, poses a difficult problem because of inherent nonlinearities and frequently changing process dynamics. Researchers at the U.S. Bureau of Mines have developed a technique for effectively controlling such systems. This technique successfully combines the process control capabilities of fuzzy logic and the search capabilities of genetic algorithms. Fuzzy logic offers an effective mechanism for handling nonlinearities, while genetic algorithms can provide fuzzy logic controllers with real-time adaptive capabilities. This Bureau-developed technique is applied to a laboratory acid-base neutralization experiment. Nonlinearities in the laboratory system are associated with the logarithmic pH scale and the changing process dynamics are due to alterations in pH and buffering capacity input solutions. Results indicate fuzzy logic controllers augmented with genetic algorithms offer a powerful alternative to conventional process control techniques in such nonlinear, rapidly changing systems.

Jan 1, 1992

By Paul F. Thiele

The mining industry of Georgia, while not as large as in some other states, is still an important part of the economy. Total value of mineral production in 1966 was $148.6 million.l/ Clays and stone produced the most income, Other minerals included sand and gravel, iron ore, mica, talc, barite, bauxite, cement, feldspar, kyanite, peat, and rare-earth metals, titanium and zircon concentrates. Georgia ranks first among the states in production of kaolin, second in fuller's earth and rare-earth concentrates, third in bauxite and kyanite, fourth in barite and ilmenite, and fifth in feldspar. It is quite likely that phosphates will one day be mined in the south eastern part: of the state, and that alumina will be produced from the extensive kaolin deposits in the central part of the state.

Jan 1, 1968

By Kevin Sierra, Orfelinda Avalo, Julio Guizado, Edwilde Yoplac, David Martinez

Mining tailings are slurry byproducts of mineral recovery. They generate serious environmental risks due to their toxicity when exposed to water and oxygen. Studies focus on eco-friendly alternatives for mitigating these environmental impacts. Processing these tailings enables a sustainable mineral production model through circular economy practices. This study evaluates using gold mining tailings to recover gold and produce bricks. Flotation tests obtained a concentrate with 86.66% gold recovery, containing sulfides (pyrite, arsenopyrite) and a tailing with silicates and oxides suitable for brick manufacturing and ornamental pieces. This approach promotes eco-friendly solutions and a greener approach to mining operations.

Feb 1, 2024

By D. H. Davidson

The basic principal in the ISL process involves the recovery of metal values by moving fluids through rock instead of moving rock. The process combines surface and sub-surface operations, with the economic performance controlled by four major factors; rates of fluid injection and production from wells; the rate of mineral solubilization; the volume of rock swept by the fluid; and the volume of solution processed through the system. This paper discusses various technical and economic parameters affecting these four factors and how they impact project costs.

Jan 1, 1985

By A. Haghighat, B. Lattimer

"Mine face ignition due to a high levels of methane is one of the most common fire incidents in underground coal mines. This work exams ignition scenarios in continuous miner headings. Depending on the magnitude of the ignition or resulting fire, the ventilation curtain in the continuous miner (CM) heading may be damaged or dislodged, affecting the ventilation into the area. A computational study was conducted to investigate the effects of different levels of damage to the ventilation curtain on the ventilation flow into the CM area. The computational fluid dynamics software Fire Dynamics Simulator (FDS), Version 6.0 was used to predict the conditions that develop due to a 200 kW fire in the coal mine face following a methane ignition with different levels of curtain damage. Smoke layer depth, temperatures and mass flow into the CM area were used to evaluate the impact of no damage to the curtain, partially dislodged curtain, and fully removed of the curtain. Partial removal of the curtain allowed more smoke to accumulate in the CM area and a reduction in ventilation into the CM area. With full removal of the curtain, the smoke accumulated through the entire depth of the CM area and flowed out the entrance to the CM area and the ventilation completely bypassed the region. INTRODUCTION Active working faces in underground coal mines are one the most hazardous locations in terms of fire events. According to Mine Safety and Health Administration (MSHA) data analysis, the highest number of non-fatal fire incidents was reported at mining faces, intersections and crosscut areas in comparison with other locations from 2000 to 2012. About 464 fires happened at active working faces from 2000 to 2012, most consisting of a methane ignition, in some cases followed by localized fire. These are high risk incidents due to the potential to raise float dust and damage ventilation systems, particularly auxiliary systems such as curtain or tubing. Depending on the magnitude of the ignition or fire, the ventilation curtain in the continuous miner (CM) area may be damaged or dislodged, affecting the ventilation into the area. Five computational fluid dynamics (CFD) scenarios were considered to investigate the smoke layer depth, temperature, visibility, mass flow rate, and the behavior of airflow in an entry with a continuous miner (CM) located in it. The state of the auxiliary ventilation was varied based on the assumption that as an ignition increases it magnitude it will affect ventilation curtain proportionally. Visibility and temperature along the height of the entry at different sections were investigated and the interface height at each section was determined. Also, the fresh air height was studied for tenability analysis in future. FDS, Version 6.0 was used to predict the conditions that develop due to a 200 kW fire on the coal mine face following a methane ignition with different levels of curtain damage. Smoke view software was used as the post processor to visualize and analyze methane fire behavior at the face. Most entry fires are reported as fuel-controlled fires as they are rarely restricted to air access (Ingason et al, 2014). The working face fire in the following models was assumed to be a fuel-controlled fire."

Jan 1, 2016

By Andrew Burton, Damian Schofield, Jeremy Noond

This paper will introduce and discuss a range of techniques that utilise new developments in Computer Graphics (CG) and Virtual Reality (VR) for the investigation of incidents and accidents in mining environments. The future of mining safety may not be totally led by the demands of the mine operators, but sometimes by the academics, commercial software developers and legal pioneers who generate new ideas and products and set admissibility precedents which may change the way certain traditional investigative operations are performed. In any accident investigation the outcome from the investigating team is often a complex affair and the results of the investigation are often reported in large, convoluted documents. Computer-generated forensic reconstructions allow investigators to present accident scenarios in an accessible and easily understood, visual manner. Surveys in the US have also shown that people have increased recall of computer-generated images over many other forms of evidence. The AIMS Research Unit in the UK have been pioneering the use of Computer Graphics (CG) and Virtual Reality (VR) technology for both industrial and road traffic accident reconstruction. This paper and accompanying presentation will contain examples of forensic reconstructions developed by the authors that explain some of the methodologies used to ensure admissibility of this type of digital evidence. The paper will contain a number of case studies based on UK and International industrial accidents. The paper will focus on how AIMS Research is extending the capabilities of the accident reconstructions created to take advantage of the latest developments in VR technology. As digital technology makes its impact within professional and commercial fields, computer generated forensic reconstructions will form important admissible evidence in the courtrooms of the future. The technology will also make a great impact in the way we train our workforces, with highly visual three-dimensional (3D) interactive training tools becoming the norm. Acceptance by the public, courts and workforce is an important issue, and implementation strategies must be considered carefully.

Jan 1, 2002

By Osvaldo Bascur

Large metallurgical complexes have more data than a small city and much of it is "real time," changing rapidly as internal and external conditions evolve. As corporations buy and sell assets and reengineer their staff, the structures and tools that were used to understand these data are lost. This results in significant deterioration in the ability to maintain a "smart" operation. The solution is to use the sophisticated new tools built for the Internet so as to leverage information in a familiar browser format that people can use and understand. This paper describes the use of Internet technologies with plant data. Examples are drawn from existing industrial sites. Users must project where this technology will lead - standing still is the most dangerous philosophy and the only one guaranteed to be obsolete. These examples show the way to leverage existing workers with information technology.

Jan 1, 2000

By E. Peuraniemi, S. Strömberg, S. Jyrkönen, A. Jokilaakso

Several sulfidic raw materials have been flash oxidized in a laboratory furnace in oxidizing atmospheres at temperatures of 500-1100°C. Chemical analysis was used to determine the oxidation degree, and optical and scanning electron microscopy combined with energy dispersive analysis were used for characterization of the reacted particles. The studied materials included both Cu and Ni concentrates and mattes. In fixed conditions, the temperature dependence of sulphur removal rate was found to be equal for all the copper concentrates studied. Nickel concentrates and Cu- and Ni-mattes were, however, found to be less reactive. Most of the particles were found to spheroidize and to fragment to small droplets under intensively oxidizing conditions. The product particles were frequently found to be iron oxide cenospheres or dense spheres with a composition of mixed Cu-(Ni-)Fe oxides.

Jan 1, 1998

Those who have had an occasion to apply geostatistics to the estimation of ore reserves are familiar with the conventional approaches of estimating average grade of quality values for arrays of regular grid squares or blocks. Further, the technology to perform geostatistical analysis and prediction for irregular two-dimensional areas has been available in a practical, readily useable form for some time. However, the generalization of this technology into three dimensions has been hampered by lack of a suitable geometrical characterization for realistic, three dimensional shapes and volumes. The extension of these estimation techniques into three dimensions has now been made possible by a successful integration of the volume modelling capabilities of 3D Component Modelling with proven 3D Geostatistical Techniques. The result is a powerful new technique for mineral ore reserves estimation in a practical, useable form. The technique allows direct geostatistical estimation of grade and quality values for precisely defined, irregular, realistic, geological, and mining shapes or volumes. This paper describes the two technologies, their integration and their application in practice to the estimation of mineral ore reserves. The paper closes with a discussion of the benefits provided by the new approach, in terms of accuracy, efficiency and practicality.

Jan 1, 1991

By Chulho C. Song, Liam Coleman

Alkaline pressure oxidation (POX) is an oxidative pre-treatment option that is commercially used for high-carbonate sulfidic gold ores. The high carbonate grades within the feed ore shifts the ideal operating pH to a basic regime. Compared with acidic POX, alkaline POX typically requires additional steam input due to a lower sulfur oxidation load and a high rate of in-situ carbon dioxide generation that needs to be vented along with steam. The cost of this steam addition is the largest differentiator between acid POX operation and alkaline POX from a cost comparison. However, alkaline POX can offset these costs through reduced acid usage for pre-acidulation and decreased alkali reagent consumption for subsequent neutralization. This paper reviews the specific operating cost impacts of acid/base consumption between alkaline and acidic POX with ores which require pre-acidulation, the overall economics of alkaline POX, and the regimes in which alkaline POX is economically favorable. The findings aim to guide industry professionals in making informed decisions for alkaline POX adoption by providing a summary view of its operational benefits and costs, contributing to the development of cost-effective and sustainable gold ore processing techniques.

Feb 1, 2025

By J. Mark Richardson, Mary S. Sredanovic

The use of computerized steady-state process design balance systems has reduced engineering man-hours by as much as 80 to 1 over conventional manual balance calculations. The popularity and widespread use of such systems by the minerals industry increased dramatically in recent years, but these systems were mainly available for use on large main frame computers and lacked graphic capability. A considerable amount of engineering manpower was required to "conceptualize" a process flowsheet. After sketching the flowsheet layout, the engineer was still faced in most cases with a time-consuming reduction of his graphic concept of the problem to numerical data required by the balance program. Furthermore, output from these early systems was usually in tabular numeric form. The computer results then were transferred manually to a pictorial representation of the process. A new process design balance system has been developed which runs on a popular and inexpensive personal computer. This system combines modern Computer Aided Design (CAD) principles and the graphics capabilities of the personal computer to allow the process engineer to define a flowsheet problem while creating a process flow diagram. The system provides balance results in both pictorial and tabular form. Past, present, and potential applications of the system are discussed, and an analysis of the cost benefits derived from its use are provided.

Jan 1, 1985

By Patrick Oriez, Chris Norris, Alain Mercusot

"Temporary mechanical ventilation is one of the fundamental requirements in guaranteeing a healthy atmosphere in underground construction works in order to protect the health of persons working on the site. It is therefore essential to conceive a system which meets the requirements of the whole of the worksite and for all phases of work which takes into account all aspects pertaining to its design, dimensioning, justification, installation, maintenance and validation. In doing so, the ventilation design and the selected apparatus to be installed shall meet with the degree of health protection and the quality of air of the worksite as defined by the legislation in force in France, through limiting the concentration of the different pollutants associated with the site activities. Consequently, when presenting a mechanical ventilation project, all of the participating parties and especially the contractor make a commitment to guarantee sufficient volumes (or airflow rates) of fresh (non-polluted and oxygenated) air and extracted (polluted) air in order to meet these limitations and maintain them in all conceivable site configurations. This article sets out the most important aspects of the implementation of a ventilation project from the initial design stage through to its application, discussing French legislation, ventilation principles, calculations and techniques with regards to underground construction sites. BASICS OF VENTILATION Mechanical ventilation studies are concerned with all of the site workstations and work phases which are sources of pollution and apply to all zones of the underground worksite with the goal of maintaining the concentration or composition of this pollution below the permitted levels and comply with the following three basic principles which are complementary to one another without being in contradiction. •,The first principle consists in eliminating or limiting as much as possible the emission of any polluting, irritant, or dangerous substances, by specifying appropriate construction techniques and equipment (use of electric motors, combustion engine equipment: filters, tanks, catalyzers, use of less polluting explosives, damping down dust with water or wetting products, damping down and diluting certain gases using water mists). •,The second principle is designed to capture residual polluting substances emitted close to the source in order to prevent them from spreading into the worksite atmosphere (extraction ventilation with ducting up to the source – upstream of the extractor fan – and use of downstream filters before expelling the polluted air to the exterior). •,The third principle involves accompanying the capture of the pollutants with additional blowing ventilation specific treatment of substances dissipated by and distant from the source of pollution (acceleration of the drift air flow in order to confine dust and better capture it, supply ventilation with ducting in order to dilute the gases emitted and discharge them to the exterior)."

Jan 1, 2016

By R. Schmidt

The computational fluid dynamics (CFD) technique was used to analyze and optimize the design of the dynamic air classifier integral to Raymond® Bowl Mills. Flow patterns and particle behaviors were modeled in the RB Bowl Mill equipped with various classifier designs. These CFD simulations resulted in the development of a hybrid turbine classifier that has now been field-tested, yielding significant improvements to both mill throughput and product size distribution. This paper demonstrates the viability of CFD as a tool for air classifier design and as a technique that can be extrapolated for use with other pulverizer and classifier arrangements.

Jan 1, 2004